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Atrial septal defect

Atrial septal defect (ASD) is a congenital heart defect in which blood flows between the atria (upper chambers) of the heart. Some flow is a normal condition both pre-birth and immediately post-birth via the foramen ovale; however, when this does not naturally close after birth it is referred to as a patent (open) foramen ovale (PFO). It is common in patients with a congenital atrial septal aneurysm (ASA).

After PFO closure the atria normally are separated by a dividing wall, the interatrial septum. If this septum is defective or absent, then oxygen-rich blood can flow directly from the left side of the heart to mix with the oxygen-poor blood in the right side of the heart; or the opposite, depending on whether the left or right atrium has the higher blood pressure. In the absence of other heart defects, the left atrium has the higher pressure. This can lead to lower-than-normal oxygen levels in the arterial blood that supplies the brain, organs, and tissues. However, an ASD may not produce noticeable signs or symptoms, especially if the defect is small. Also, in terms of health risks, people who have had a cryptogenic stroke are more likely to have a PFO than the general population.

A cardiac shunt is the presence of a net flow of blood through a defect, either from left to right or right to left. The amount of shunting present, if any, determines the hemodynamic significance of the ASD. A right-to-left-shunt results in venous blood entering the left side of the heart and into the arterial circulation without passing through the pulmonary circulation to be oxygenated. This may result in the clinical finding of cyanosis, the presence of bluish-colored skin, especially of the lips and under the nails.

During development of the baby, the interatrial septum develops to separate the left and right atria. However, a hole in the septum called the foramen ovale allows blood from the right atrium to enter the left atrium during fetal development. This opening allows blood to bypass the nonfunctional fetal lungs while the fetus obtains its oxygen from the placenta. A layer of tissue called the septum primum acts as a valve over the foramen ovale during fetal development. After birth, the pressure in the right side of the heart drops as the lungs open and begin working, causing the foramen ovale to close entirely. In about 25% of adults, the foramen ovale does not entirely seal. In these cases, any elevation of the pressure in the pulmonary circulatory system (due to pulmonary hypertension, temporarily while coughing, etc.) can cause the foramen ovale to remain open.

Types
[[Image:Schematic drawing of various types of atrial septal defect.png|right|thumb|350px|Schematic drawing showing the location of different types of ASD, the view is into an opened right atrium.

HV: right ventricle; VCS: superior vena cava; VCI: inferior vena cava

1: upper sinus venosus defect; 2: lower sinus venosus defect; 3: secundum defect; 4: defect involving coronary sinus; 5; primum defect.]] The six types of atrial septal defects are differentiated from each other by whether they involve other structures of the heart and how they are formed during the developmental process during early fetal development.

Ostium secundum
The ostium secundum atrial septal defect is the most common type of atrial septal defect and comprises 6–10% of all congenital heart diseases. It involves a patent ostium secundum (that is, a patent foramen secundum). The secundum atrial septal defect usually arises from an enlarged foramen ovale, inadequate growth of the septum secundum, or excessive absorption of the septum primum. About 10 to 20% of individuals with ostium secundum ASDs also have mitral valve prolapse.

An ostium secundum ASD accompanied by an acquired mitral valve stenosis is called Lutembacher's syndrome.

Natural history
Most individuals with an uncorrected secundum ASD do not have significant symptoms through early adulthood. More than 70% develop symptoms by about 40 years of age. Symptoms are typically decreased exercise tolerance, easy fatigability, palpitations, and syncope.

Complications of an uncorrected secundum ASD include pulmonary hypertension, right-sided congestive heart failure.

While pulmonary hypertension is unusual before 20 years of age, it is seen in 50% of individuals above the age of 40. Progression to Eisenmenger's syndrome occurs in 5 to 10% of individuals late in the disease process.

Patent foramen ovale
A patent foramen ovale (PFO) is a remnant opening of the fetal foramen ovale, which often closes after a person's birth. This remnant opening is caused by the incomplete fusion of the septum primum and the septum secundum; in healthy hearts, this fusion form the fossa ovalis, a portion of the interatrial septum which corresponds to the location of the foramen ovale in the fetus. In medical use, the term "patent" means open or unobstructed. In about 25% of people, the foramen ovale does not close, leaving them with a PFO or at least with what some physicians classify as a "pro-PFO", which is a PFO that is normally closed, but can open under increased right atrial pressure. On echocardiography, shunting of blood may not be noted except when the patient coughs.

PFO is linked to stroke, sleep apnea, migraine with aura, cluster headache, decompression sickness, Raynaud's phenomenon, hyperventilation syndrome, transient global amnesia (TGA), and leftsided carcinoid heart disease (mitral valve). No cause is established for a foramen ovale to remain open instead of closing, but heredity and genetics may play a role. In rats research showed a link to the amount of Cryptosporidium infestation and the number of newborn rats that failed to close their foramen ovale. PFO is not treated in the absence of other symptoms.

The mechanism by which a PFO may play a role in stroke is called paradoxical embolism. In the case of PFO, a blood clot from the venous circulatory system is able to pass from the right atrium directly into the left atrium via the PFO, rather than being filtered by the lungs, and thereupon into systemic circulation toward the brain. Also multiple substances -including the prothrombotic agent serotonin- are shunted bypassing the lungs. PFO is common in patients with an atrial septal aneurysm (ASA), a much rarer condition, which is also linked to cryptogenic (i.e., of unknown cause) stroke.

PFO is more common in people with cryptogenic stroke than in those with a stroke of known cause. While PFO is present in 25% in the general population, the probability of someone having a PFO increases to about 40 to 50% in those who have had a cryptogenic stroke, and more so in those who have a stroke before the age of 55. Treatment with anticoagulant and antiplatelet medications in this group appear similar.

Ostium primum
A defect in the ostium primum is occasionally classified as an atrial septal defect, but it is more commonly classified as an atrioventricular septal defect. Ostium primum defects are less common than ostium secundum defects. This type of defect is usually associated with Down syndrome.

Sinus venosus
A sinus venosus ASD is a type of atrial septum defect in which the defect involves the venous inflow of either the superior vena cava or the inferior vena cava.

A sinus venosus ASD that involves the superior vena cava makes up 2 to 3% of all interatrial communication. It is located at the junction of the superior vena cava and the right atrium. It is frequently associated with anomalous drainage of the right-sided pulmonary veins into the right atrium (instead of the normal drainage of the pulmonary veins into the left atrium).

Common or single atrium
Common (or single) atrium is a failure of development of the embryologic components that contribute to the atrial septal complex. It is frequently associated with heterotaxy syndrome.

Mixed
The interatrial septum can be divided into five septal zones. If the defect involves two or more of the septal zones, then the defect is termed a mixed atrial septal defect.

Complications
Due to the communication between the atria that occurs in ASDs, disease entities or complications from the condition are possible. Patients with an uncorrected atrial septal defect may be at increased risk for developing a cardiac arrhythmia, as well as more frequent respiratory infections.

Decompression sickness
ASDs, and particularly PFOs, are a predisposing venous blood carrying inert gases, such as helium or nitrogen does not pass through the lungs. The only way to release the excess inert gases from the body is to pass the blood carrying the inert gases through the lungs to be exhaled. If some of the inert gas-laden blood passes through the PFO, it avoids the lungs and the inert gas is more likely to form large bubbles in the arterial blood stream causing decompression sickness.

Eisenmenger's syndrome
If a net flow of blood exists from the left atrium to the right atrium, called a left-to-right shunt, then an increase in the blood flow through the lungs happens. Initially, this increased blood flow is asymptomatic, but if it persists, the pulmonary blood vessels may stiffen, causing pulmonary hypertension, which increases the pressures in the right side of the heart, leading to the reversal of the shunt into a right-to-left shunt. Reversal of the shunt occurs, and the blood flowing in the opposite direction through the ASD is called Eisenmenger's syndrome, a rare and late complication of an ASD.

Paradoxical embolus
Venous thrombus (clots in the veins) are quite common. Embolizations (dislodgement of thrombi) normally go to the lung and cause pulmonary emboli. In an individual with ASD, these emboli can potentially enter the arterial system, which can cause any phenomenon attributed to acute loss of blood to a portion of the body, including cerebrovascular accident (stroke), infarction of the spleen or intestines, or even a distal extremity (i.e., finger or toe).

This is known as a paradoxical embolus because the clot material paradoxically enters the arterial system instead of going to the lungs.

Migraine
Some recent research has suggested that a proportion of cases of migraine may be caused by PFO. While the exact mechanism remains unclear, closure of a PFO can reduce symptoms in certain cases. This remains controversial; 20% of the general population has a PFO, which for the most part, is asymptomatic. About 20% of the female population has migraines, and the placebo effect in migraine typically averages around 40%. The high frequency of these facts make finding statistically significant relationships between PFO and migraine difficult (i.e., the relationship may just be chance or coincidence). In a large randomized controlled trial, the higher prevalence of PFO in migraine patients was confirmed, but migraine headache cessation was not more prevalent in the group of migraine patients who underwent closure of their PFOs.

Causes

 * Down syndrome – patients with Down syndrome have higher rates of ASDs, especially a particular type that involves the ventricular wall. As many as one half of Down syndrome patients have some type of septal defect.
 * Ebstein's anomaly – about 50% of individuals with Ebstein anomaly have an associated shunt between the right and left atria, either an atrial septal defect or a patent foramen ovale.
 * Fetal alcohol syndrome – about one in four patients with fetal alcohol syndrome has either an ASD or a ventricular septal defect.
 * Holt–Oram syndrome – both the osteium secundum and osteum primum types of ASD are associated with Holt–Oram syndrome
 * Lutembacher's syndrome – the presence of a congenital ASD along with acquired mitral stenosis

Mechanisms
In unaffected individuals, the chambers of the left side of the heart are under higher pressure than the chambers of the right side because the left ventricle has to produce enough pressure to pump blood throughout the entire body, while the right ventricle needs only to produce enough pressure to pump blood to the lungs.

In the case of a large ASD (> 9 mm), which may result in a clinically remarkable left-to-right shunt, blood shunts from the left atrium to the right atrium. This extra blood from the left atrium may cause a volume overload of both the right atrium and the right ventricle. If untreated, this condition can result in enlargement of the right side of the heart and ultimately heart failure.

Any process that increases the pressure in the left ventricle can cause worsening of the left-to-right shunt. This includes hypertension, which increases the pressure that the left ventricle has to generate to open the aortic valve during ventricular systole, and coronary artery disease which increases the stiffness of the left ventricle, thereby increasing the filling pressure of the left ventricle during ventricular diastole. The left-to-right shunt increases the filling pressure of the right heart (preload) and forces the right ventricle to pump out more blood than the left ventricle. This constant overloading of the right side of the heart causes an overload of the entire pulmonary vasculature. Eventually, pulmonary hypertension may develop.

The pulmonary hypertension will cause the right ventricle to face increased afterload. The right ventricle is forced to generate higher pressures to try to overcome the pulmonary hypertension. This may lead to right ventricular failure (dilatation and decreased systolic function of the right ventricle).

If the ASD is left uncorrected, the pulmonary hypertension progresses and the pressure in the right side of the heart becomes greater than the left side of the heart. This reversal of the pressure gradient across the ASD causes the shunt to reverse – a right-to-left shunt. This phenomenon is known as Eisenmenger's syndrome. Once right-to-left shunting occurs, a portion of the oxygen-poor blood gets shunted to the left side of the heart and ejected to the peripheral vascular system. This causes signs of cyanosis.

Diagnosis

Most individuals with a significant ASD are diagnosed in utero or in early childhood with the use of ultrasonography or auscultation of the heart sounds during physical examination. Some individuals with an ASD have surgical correction of their ASD during childhood. The development of signs and symptoms due to an ASD are related to the size of the intracardiac shunt. Individuals with a larger shunt tend to present with symptoms at a younger age.

Adults with an uncorrected ASD present with symptoms of dyspnea on exertion (shortness of breath with minimal exercise), congestive heart failure, or cerebrovascular accident (stroke). They may be noted on routine testing to have an abnormal chest X-ray or an abnormal ECG and may have atrial fibrillation. If the ASD causes a left-to-right shunt, the pulmonary vasculature in both lungs may appear dilated on chest X-ray, due to the increase in pulmonary blood flow.

Physical examination
The physical findings in an adult with an ASD include those related directly to the intracardiac shunt and those that are secondary to the right heart failure that may be present in these individuals.

In unaffected individuals, respiratory variations occur in the splitting of the second heart sound (S2). During respiratory inspiration, the negative intrathoracic pressure causes increased blood return into the right side of the heart. The increased blood volume in the right ventricle causes the pulmonic valve to stay open longer during ventricular systole. This causes a normal delay in the P2 component of S2. During expiration, the positive intrathoracic pressure causes decreased blood return to the right side of the heart. The reduced volume in the right ventricle allows the pulmonic valve to close earlier at the end of ventricular systole, causing P2 to occur earlier.

In individuals with an ASD, a fixed splitting of S2 occurs because the extra blood return during inspiration gets equalized between the left and right atria due to the communication that exists between the atria in individuals with ASD.

The right ventricle can be thought of as continuously overloaded because of the left-to-right shunt, producing a widely split S2. Because the atria are linked via the atrial septal defect, inspiration produces no net pressure change between them, and has no effect on the splitting of S2. Thus, S2 is split to the same degree during inspiration as expiration, and is said to be "fixed".

Echocardiography
In transthoracic echocardiography, an atrial septal defect may be seen on color flow imaging as a jet of blood from the left atrium to the right atrium.

If agitated saline is injected into a peripheral vein during echocardiography, small air bubbles can be seen on echocardiographic imaging. Bubbles traveling across an ASD may be seen either at rest or during a cough. (Bubbles only flow from right atrium to left atrium if the right atrial pressure is greater than left atrial). Because better visualization of the atria is achieved with transesophageal echocardiography, this test may be performed in individuals with a suspected ASD which is not visualized on transthoracic imaging. Newer techniques to visualize these defects involve intracardiac imaging with special catheters typically placed in the venous system and advanced to the level of the heart. This type of imaging is becoming more common and involves only mild sedation for the patient typically.

If the individual has adequate echocardiographic windows, use of the echocardiogram to measure the cardiac output of the left ventricle and the right ventricle independently is possible. In this way, the shunt fraction can be estimated using echocardiography.

Transcranial doppler bubble study
A less invasive method for detecting a PFO or other ASDs than transesophagal ultrasound is transcranial Doppler with bubble contrast. This method reveals the cerebral impact of the ASD or PFO.

Electrocardiogram
The ECG findings in atrial septal defect vary with the type of defect the individual has. Individuals with atrial septal defects may have a prolonged PR interval (a first-degree heart block). The prolongation of the PR interval is probably due to the enlargement of the atria common in ASDs and the increased distance due to the defect itself. Both of these can cause an increased distance of internodal conduction from the SA node to the AV node.

In addition to the PR prolongation, individuals with a primum ASD have a left axis deviation of the QRS complex, while those with a secundum ASD have a right axis deviation of the QRS complex. Individuals with a sinus venosus ASD exhibit a left axis deviation of the P wave (not the QRS complex).

A common finding in the ECG is the presence of incomplete right bundle branch block, which is so characteristic that if it is absent, the diagnosis of ASD should be reconsidered.

Patent foramen ovale
Most patients with a PFO are asymptomatic and do not require any specific treatment. However, those who develop a stroke require further workup to identify the etiology. In those where a comprehensive evaluation is performed and an obvious etiology is not identified, they are defined as having a cryptogenic stroke. The mechanism for stroke is such individuals is likely embolic due to paradoxical emboli, a left atrial appendage clot, a clot on the inter-atrial septum, or within the PFO tunnel.

PFO closure
Until recently, patients with PFO and cryptogenic stroke were treated with antiplatelet therapy only. Previous studies did not identify a clear benefit of PFO closure over antiplatelet therapy in reducing recurrent ischemic stroke. However, based on new evidence  and systematic review in the field, percutaneous PFO closure in addition to antiplatelet therapy is suggested for all who meet all the following criteria:
 * Age ≤ 60 years at onset of first stroke,
 * Embolic-appearing cryptogenic ischemic stroke (i.e., no evident source of stroke despite a comprehensive evaluation), and
 * PFO with a right-to-left interatrial shunt detected by bubble study (echocardiogram)

A variety of PFO closure devices may be implanted via catheter-based procedures.

Medical therapy
Based on the most up to date evidence, PFO closure is more effective at reducing recurrent ischemic stroke when compared to medical therapy. In most of these studies, antiplatelet and anticoagulation were combined in the medical therapy arm. Although there is limited data on the effectiveness of anticoagulation in reducing stroke in this population, it is hypothesized that based on the embolic mechanism, that anticoagulation should be superior to antiplatelet therapy at reducing risk of recurrent stroke. A recent review of the literature supports this hypothesis recommending anticoagulation over the use of antiplatelet therapy in patients with PFO and cryptogenic stroke. However, more evidence is required comparing of PFO closure with anticoagulation or anticoagulation with antiplatelet therapy.

Atrial septal defect
Once someone is found to have an atrial septal defect, a determination of whether it should be corrected is typically made. If the atrial septal defect is causing the right ventricle to enlarge a secundum atrial septal defect should generally be closed. If the ASD is not causing problems the defect may simply be checked every two or three years. Methods of closure of an ASD include surgical closure and percutaneous closure.

Evaluation prior to correction
Prior to correction of an ASD, an evaluation is made of the severity of the individual's pulmonary hypertension (if present at all) and whether it is reversible (closure of an ASD may be recommended for prevention purposes, to avoid such a complication in the first place. Pulmonary hypertension is not always present in adults who are diagnosed with an ASD in adulthood).

If pulmonary hypertension is present, the evaluation may include a right heart catheterization. This involves placing a catheter in the venous system of the heart and measuring pressures and oxygen saturations in the superior vena cava, inferior vena cava, right atrium, right ventricle, and pulmonary artery, and in the wedge position. Individuals with a pulmonary vascular resistance (PVR) less than 7 wood units show regression of symptoms (including NYHA functional class). However, individuals with a PVR greater than 15 wood units have increased mortality associated with closure of the ASD.

If the pulmonary arterial pressure is more than two-thirds of the systemic systolic pressure, a net left-to-right shunt should occur at least 1.5:1 or evidence of reversibility of the shunt when given pulmonary artery vasodilators prior to surgery. (If Eisenmenger's physiology has set in, the right-to-left shunt must be shown to be reversible with pulmonary artery vasodilators prior to surgery.)

Surgical mortality due to closure of an ASD is lowest when the procedure is performed prior to the development of significant pulmonary hypertension. The lowest mortality rates are achieved in individuals with a pulmonary artery systolic pressure less than 40 mmHg. If Eisenmenger's syndrome has occurred, a significant risk of mortality exists regardless of the method of closure of the ASD. In individuals who have developed Eisenmenger's syndrome, the pressure in the right ventricle has raised high enough to reverse the shunt in the atria. If the ASD is then closed, the afterload that the right ventricle has to act against has suddenly increased. This may cause immediate right ventricular failure, since it may not be able to pump the blood against the pulmonary hypertension.

Surgical closure

Surgical closure of an ASD involves opening up at least one atrium and closing the defect with a patch under direct visualization.

Catheter procedure
Percutaneous device closure involves the passage of a catheter into the heart through the femoral vein guided by fluoroscopy and echocardiography. An example of a percutaneous device is a device which has discs that can expand to a variety of diameters at the end of the catheter. The catheter is placed in the right femoral vein and guided into the right atrium. The catheter is guided through the atrial septal wall and one disc (left atrial) is opened and pulled into place. Once this occurs, the other disc (right atrial) is opened in place and the device is inserted into the septal wall. This type of PFO closure is more effective than drug or other medical therapies for decreasing the risk of future thromboembolism. The most common adverse effect of PFO device closure is new-onset atrial fibrillation. Other complications, all rare, include device migration, erosion and embolization and device thrombosis or formation of an inflammatory mass with risk for recurrent ischemic stroke.

Percutaneous closure of an ASD is currently only indicated for the closure of secundum ASDs with a sufficient rim of tissue around the septal defect so that the closure device does not impinge upon the superior vena cava, inferior vena cava, or the tricuspid or mitral valves. The Amplatzer Septal Occluder (ASO) is commonly used to close ASDs. The ASO consists of two self-expandable round discs connected to each other with a 4-mm waist, made up of 0.004– to 0.005-inch Nitinol wire mesh filled with Dacron fabric. Implantation of the device is relatively easy. The prevalence of residual defect is low. The disadvantages are a thick profile of the device and concern related to a large amount of nitinol (a nickel-titanium compound) in the device and consequent potential for nickel toxicity.

Percutaneous closure is the method of choice in most centres. Studies evaluating percutaneous ASD closure among pediatric and adult population show that this is relatively safer procedure and has better outcomes with increasing hospital volume.

Epidemiology
As a group, atrial septal defects are detected in one child per 1500 live births. PFOs are quite common (appearing in 10–20% of adults), but when asymptomatic go undiagnosed. ASDs make up 30 to 40% of all congenital heart diseases that are seen in adults.

The ostium secundum atrial septal defect accounts for 7% of all congenital heart lesions. This lesion shows a male:female ratio of 1:2.

title: Atrial septal defect


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Anesthesia awareness

Awareness under anesthesia, also referred to as intraoperative awareness or accidental awareness during general anesthesia (AAGA), is a rare complication of general anesthesia where patients regain varying levels of consciousness during their surgical procedures. While anesthesia awareness is possible without resulting in any long-term memory of the experience, it is also possible for victims to have awareness with explicit recall, where they can remember the events related to their surgery (intraoperative awareness with explicit recall).

Intraoperative awareness with explicit recall is an infrequent condition with potentially devastating psychological consequences. While it has gained popular recognition in media, research shows that it only occurs at an incidence rate of 0.1–0.2%. Patients report a variety of experiences, ranging from vague, dreamlike states to being fully awake, immobilized, and in pain from the surgery. Intraoperative awareness is usually caused by the delivery of inadequate anesthetics relative to the patient's requirements. Risk factors can be anesthetic (e.g., use of neuromuscular blockade drugs, use of intravenous anesthetics, technical/mechanical errors), surgical (e.g., cardiac surgery, trauma/emergency, C-sections), or patient-related (e.g., reduced cardiovascular reserve, history of substance use, history of awareness under anesthesia).

Currently, the mechanism behind consciousness and memory under anesthesia is unknown, although there are many working hypotheses. However, intraoperative monitoring of anesthetic level with bispectral index (BIS) or end-tidal anesthetic concentration (ETAC) may help to reduce the incidence of intraoperative awareness, although clinical trials have yet to show a decreased incidence of AAGA with the BIS monitor.

There are also many preventative techniques considered for high-risk patients, such as pre-medicating with benzodiazepines, avoiding complete muscle paralysis, and managing patients' expectations. Diagnosis is made postoperatively by asking patients about potential awareness episodes and can be aided by the modified Brice interview questionnaire. A common but devastating complication of intraoperative awareness with recall is the development of post-traumatic stress disorder (PTSD) from the events experienced during surgery. Prompt diagnosis and referral to counseling and psychiatric treatment are crucial to the treatment of intraoperative awareness and the prevention of PTSD.

Signs and symptoms
Intraoperative awareness can present with a variety of signs and symptoms. A large proportion of patients report vague, dreamlike experiences, while others report specific intraoperative events, such as:
 * hearing noises or conversations in the operating room
 * remembering details of the operation
 * sensing pain associated with intubation or surgery
 * having weakness or muscle paralysis
 * feeling anxiety, helplessness, or an impending sense of doom

Intraoperative signs that may indicate patient awareness include:
 * hypertension (high blood pressure)
 * tachycardia (high heart rate)
 * patient movement
 * tachypnea
 * intravenous anesthesia line infiltrated or occluded

Patients under anesthesia are paralyzed if a neuromuscular blockade drug, a type of muscle relaxant, has been given as part of general anesthesia. When paralyzed, patients may not be able to communicate their distress or alert the operating room staff of their consciousness until the paralytic wears off. After surgery, recognition of the symptoms of an awareness event may be delayed. One review showed that only about 35% of patients are able to report an awareness event immediately after the surgery, with the rest remembering the experience weeks to months afterward. Depending on the awareness experience, patients may have postoperative psychological problems that range from mild anxiety to post-traumatic stress disorder (PTSD). PTSD is characterized by recurrent anxiety, irritability, flashbacks or nightmares, avoidance of triggers related to the trauma, and sleep disturbances.

Paralytic and muscle relaxant use
The biggest risk factor is anesthesia performed by unsupervised trainees and the use of a medication that induces muscle paralysis, such as suxamethonium (succinylcholine) or non-depolarizing neuromuscular blocking drugs (muscle relaxants). During general anesthesia, the patient's muscles may be paralyzed in order to facilitate tracheal intubation or surgical exposure (abdominal and thoracic surgery can be performed only with adequate muscle relaxation). Because the patient cannot breathe for themselves, mechanical ventilation must be used. The paralyzing agent does not cause unconsciousness or take away the patient's ability to feel pain, but does prevent the patient from breathing, so the airway (trachea) must be protected and the lungs ventilated to ensure adequate oxygenation of the blood and removal of carbon dioxide.

A fully paralyzed patient is unable to move, speak, blink the eyes, or otherwise respond to the pain. If neuromuscular blocking drugs are used, this causes skeletal muscle paralysis but does not interfere with cardiac or smooth muscle or the functioning of the autonomic nervous system, so heart rate, blood pressure, intestinal peristalsis, sweating and lacrimation are unaffected. The patient cannot signal distress and may not exhibit the signs of awareness that would be expected to be detectable by clinical vigilance, because other drugs used during anaesthesia may block or obtund these.

Many types of surgery do not require the patient to be paralyzed. A patient who is anesthetized but not paralyzed can move in response to a painful stimulus if the analgesia is inadequate. This may serve as a warning sign that the anesthetic depth is inadequate. Movement under general anesthesia does not imply full awareness but is a sign that the anesthesia is light. Even without the use of neuromuscular blocking drugs the absence of movement does not necessarily imply amnesia.

Light anesthesia
For certain operations, such as caesarean section, or in hypovolemic patients or patients with minimal cardiac reserve, the anesthesia provider may aim to provide "light anesthesia" and should discuss this with patients to warn them. During such circumstances, consciousness and recall may occur because judgments of depth of anesthesia are not precise. The anesthesia provider must weigh the need to keep the patient safe and stable with the goal of preventing awareness. Sometimes, it is necessary to provide lighter anesthesia in order to preserve the life of the patient. "Light" anesthesia means less drugs by the intravenous route or via inhalational means, leading to less cardiovascular depression (hypotension) but permitting "awareness" in the anesthetized subject.

Anesthesiologist error
Human errors include repeated attempts at intubation during which the short-acting anesthetic may wear off but the paralyzing drug does not; esophageal intubation; inadequate drug dose; a drug given by the wrong route or a wrong drug given; drugs given in the wrong sequence; inadequate monitoring; patient abandonment; disconnections and kinks in tubes from the ventilator; and failure to refill the anesthetic machine's vaporizers with volatile anesthetic. Other causes include unfamiliarity with techniques used, e.g. intravenous anesthetic regimes, and inexperience. Most cases of awareness are caused by inexperience and poor anesthetic technique, which can be any of the above, but also includes techniques that could be described as outside the boundaries of "normal" practice. The American Society of Anesthesiologists in 2007 released a Practice Advisory outlining the steps that anesthesia professionals and hospitals should take to minimize these risks. Other societies have released their own versions of these guidelines, including the Australian and New Zealand College of Anaesthetists.

To reduce the likelihood of awareness, anesthetists must be adequately trained, and supervised while still in training. Equipment that monitors depth of anesthesia, such as bispectral index monitoring, should not be used in isolation.

Current research attributes the incidence of AAGA to a combination of the risks mentioned above, together with ineffective practice from ODPs, anesthetic nurses, HCAs and anesthetists. The main failures include:
 * Inattention or judgment errors related to drugs and volatile agents
 * Termination of anesthesia too soon before surgery has finished, due to poor communication
 * Lack of understanding of offset times of volatile agents
 * Backflow of induction agent up a giving set
 * Failure to fill vaporizers (which is the cause of 19% of the cases of AAGA)
 * Under-dosing of induction agent during difficult intubation
 * Failure to monitor MAC (minimum alveolar concentration of inhaled anaesthetic required to prevent movement in 50% of patients in response to surgical incision)
 * Syringe swaps
 * Rushing caused by organizational or individual circumstances (often associated with staff shortage and stressful work environment)
 * Distractions caused by another member of staff

Equipment failure
Machine malfunction or misuse may result in an inadequate delivery of anesthetic. Many Boyle's machines in hospitals have the oxygen regulator serving as a slave to the pressure in the nitrous oxide regulator, to enable the nitrous oxide cut-off safety feature. If nitrous oxide delivery suffers due to a leak in its regulator or tubing, an 'inadequate' mixture can be delivered to the patient, causing awareness. Many World War II-vintage Boyle 'F' models are still functional and used in UK hospitals. Their emergency oxygen flush valves have a tendency to release oxygen into the breathing system, which, when added to the mixture set by the anesthesiologist, can lead to awareness. This may also be caused by an empty vaporizer (or nitrous oxide cylinder) or a malfunctioning intravenous pump or disconnection of its delivery tubing. Patient abandonment (when the anesthesiologist is no longer present) causes some cases of awareness and death.

Patient physiology
Very rare causes of awareness include drug tolerance, or a tolerance induced by the interaction of other drugs. Some patients may be more resistant to the effects of anesthetics than others; factors such as younger age, obesity, tobacco smoking, or long-term use of certain drugs (alcohol, opiates, or amphetamines) may increase the anesthetic dose needed to produce unconsciousness. There may be genetic variations that cause differences in how quickly patients clear anesthetics, and there may be differences in how the sexes react to anesthetics as well. In addition, anesthetic requirement is increased in persons with naturally red hair. Marked anxiety prior to the surgery can increase the amount of anesthesia required to prevent recall.

Conscious sedation
There are various levels of consciousness. Full wakefulness and general anesthesia are the two extremes of the spectrum. Conscious sedation and monitored anesthesia care (MAC) refer to an awareness somewhere in the middle of the spectrum, depending on the degree to which a patient is sedated. Monitored anesthesia care involves titration of local anesthesia along with sedation and analgesia. Awareness/wakefulness does not necessarily imply pain or discomfort. The aim of conscious sedation or MAC is to provide a safe and comfortable anesthetic while maintaining the patient's ability to follow commands.

Under certain circumstances, a general anesthetic, whereby the patient is completely unconscious, may be unnecessary or undesirable. For instance, with a caesarean delivery, the goal is to provide comfort with neuraxial anesthetic yet maintain consciousness so that the mother can participate in the birth of the child. Other circumstances may include, but are not limited to, procedures that are minimally invasive or purely diagnostic (and thus not uncomfortable). Sometimes, the patient's health may not tolerate the stress of general anesthesia. The decision to provide MAC versus general anesthesia can be complex, involving careful consideration of individual circumstances and discussion with the patient about their preferences.

Patients who undergo conscious sedation or monitored anesthesia care are never meant to be without recall. Whether a patient remembers the procedure depends on the type of anesthetic, dosages, patient physiology, and other factors. Many patients undergoing monitored anesthesia may go through profound amnesia, depending on the amount of anesthetic used.

Some patients undergo sedation for smaller procedures such as biopsies and colonoscopies and are told they will be asleep, although in fact they are getting a sedation that may allow some level of awareness as opposed to a general anesthetic.

Memory
New research has been carried out to test what people can remember after a general anesthetic, in an effort to understand anesthesia awareness more clearly and help to protect patients from experiencing it. A memory is not one simple entity; it is a system of many intricate details and networks.

Memory is currently classified under two main subsections.
 * Explicit or conscious memory, which refers to the conscious recollection of previous experiences. An example of explicit memory is remembering what you did last weekend. When it comes to an anesthetized patient, a doctor may ask the patient after undergoing general anesthesia if he or she could remember hearing any distinct sounds or words while under anesthesia. This approach is called a "recall test" because patients are asked to recall any memories they had during surgery.
 * Implicit memory or unconscious memory, which refers to the changes in performance or behavior that are produced by previous experiences but without any conscious recollection of those experiences. An example of this is a recognition test, where patients are asked to determine, after surgery, which of a selection of words could be heard during the surgery. The following scenario is an example. Patients were exposed during anesthesia to a list of words containing the word "pension". Postoperatively, when presented with the three-letter word stem PEN___ and asked to supply the first word that came to their minds beginning with those letters, they gave the word "pension" more often than "pencil" or "peninsula" or others.

Some researchers are now formally interviewing patients postoperatively to calculate the incidence of anesthesia awareness. It is good practice for the anesthesiologist to visit the patient after the operation and check that the patient was not aware. Most patients who were not unduly disturbed by their experiences do not necessarily report cases of awareness unless directly asked. Many who are greatly disturbed report their awareness but anesthesiologists and hospitals deny that it has happened. It has been found that some patients may not recall experiencing awareness until one to two weeks after undergoing surgery. It was also found that some patients require a more detailed interview to jog their memories for intraoperative experiences but these are only untraumatic cases. Some researchers have found that while anesthesia awareness does not commonly occur in minor surgeries, it may occur more frequently in more serious surgeries, and that it is good practice to warn of the possibility of awareness in those cases where it may be more likely.

Prevention
The risk of awareness is reduced by avoidance of paralytics unless necessary; careful checking of drugs, doses and equipment; good monitoring, and careful vigilance during the case. The Isolated Forearm Technique (IFT) can be used to monitor consciousness; the technique involves applying a tourniquet to the patient's upper arm before the administration of muscle relaxants, so that the forearm can still be moved consciously. The technique is considered a reference standard by which other means of monitoring consciousness can be assessed.

Because the medical staff may not know if a person is unconscious or not, it has been suggested that the staff maintain the professional conduct that would be appropriate for a conscious patient.

Monitors
Recent advances have led to the manufacture of monitors of awareness. Typically these monitor the EEG, which represents the electrical activity of the cerebral cortex, which is active when awake but quiescent under anesthesia (or in natural sleep). The monitors usually process the EEG signal down to a single number, where 100 corresponds to a patient who is fully alert, and zero corresponds to electrical silence. General anesthesia is usually signified by a number between 60 and 40 (this varies with the specific system used). There are several monitors now commercially available. These newer technologies include the bispectral index (BIS), EEG entropy monitoring, auditory evoked potentials, and several other systems such as the SNAP monitor and the Narcotrend monitor.

None of these systems are perfect. For example, they are unreliable at extremes of age (e.g., neonates, infants or the very elderly). Secondly, certain agents, such as nitrous oxide, may produce anesthesia without reducing the value of the depth monitor. This is because the molecular action of these agents (NMDA receptor antagonists) differs from that of more conventional agents, and they suppress cortical EEG activity less. Third, they are prone to interference from other biological potentials (such as EMG), or external electrical signals (such as electrosurgery). This means that the technology that will reliably monitor depth of anesthesia for every patient and every anesthetic does not yet exist. This may in part explain why a 2016 systematic review and meta analysis concluded that depth-of-anesthesia monitors had a similar effect to standard clinical monitoring on the risk of awareness during surgery

Incidence
The incidence of anesthesia awareness is variable; it seems to affect 0.2% to 0.4% of patients. This variation reflects the surgical setting as well as the physiological state of the patient; the incidence is 0.2% in general surgery, about 0.4% during caesarean section, between 1% and 2% during cardiac surgery and between 10% and 40% for anesthesia of the traumatized. The majority of these do not feel pain, although around one-third did, in a range of experience from a sore throat caused by the endotracheal tube, to traumatic pain at the incision site. The incidence is halved in the absence of neuromuscular blockade.

The quoted incidences are controversial as many cases of "awareness" are open to interpretation.

The incidence is higher and has more serious sequelae when muscle relaxants or neuromuscular-blocking drugs are used. This is because without relaxant the patient will move and the anesthesiologist will then deepen the anesthesia.

One study has indicated that this phenomenon occurs in 0.13% of patients, or between 1 and 2 per 1000. There are conflicting data, however, as another study suggested it is a rarer phenomenon, with an incidence of 0.0068%, after review of data from a population of 211,842 patients.

Postoperative interview by an anesthetist is common practice to elucidate whether awareness occurred in the case. If awareness is reported, a case review is immediately performed to identify machine, medication, or operator error.

Outcomes
Patients who experience full awareness with explicit recall may have suffered an enormous trauma due to the extreme pain of surgery. Some patients experience post-traumatic stress disorder (PTSD), leading to long-lasting after-effects such as nightmares, night terrors, flashbacks, insomnia, and in some cases even suicide. Some cases of awareness alert the patient to intra-operative errors.

A study from Sweden in 2002 attempted to follow up 18 patients for approximately 2 years after having been previously diagnosed with awareness under anesthesia. Four of the nine interviewed patients were still severely disabled due to psychiatric/psychological after-effects. All of these patients had experienced anxiety during the period of awareness, but only one had stated feeling pain. Another three patients had less severe, transient mental symptoms, although they could cope with these in daily life. Two patients denied any lasting effects from their awareness episode.

Society and culture

 * Awake, a 2007 film about anesthetic awareness.
 * Anesthesia, an award-winning horror film about anesthesia awareness.
 * Return, a Korean thriller movie about anesthesia awareness.
 * In an episode of Nip/Tuck a woman, Rhea Reynolds, experiences anesthesia awareness while having surgery to repair scarring on her face.
 * A sixth-season episode of "Grey's Anatomy", "State of Love and Trust," involves a patient waking up during removal of an abdominal tumor, and retaining full memory of the event.
 * Under: a 2006 film about anesthetic awareness.
 * 2014 Bollywood movie Heartless – the patient experienced full awareness during heart transplant.
 * 2016 episode of Shortland Street, a New Zealand hospital soap opera, the patient experienced full awareness during facelift.
 * Carol Weihrer, an American activist who experienced intraoperative awareness with recall.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Anesthesia awareness


text:
Charles Hamilton (writer)

Charles Harold St. John Hamilton (8 August 1876 – 24 December 1961) was an English writer, specialising in writing long-running series of stories for weekly magazines about recurrent casts of characters, his most frequent and famous genre being boys' public school stories, though he also wrote in other genres. He used a variety of pen-names, generally using a different name for each set of characters he wrote about, the most famous being Frank Richards for the Greyfriars School stories featuring Billy Bunter. Other important pen-names included Martin Clifford (for St Jim's), Owen Conquest (for Rookwood) and Ralph Redway (for The Rio Kid). He also wrote hundreds of stories under his real name such as the Ken King stories for The Modern Boy.

He is estimated to have written about 100 million words in his lifetime and has featured in the Guinness Book of Records as the world's most prolific author. Vast amounts of his output are available on the Friardale website.

Early life and career (1876–1906)
Hamilton was born in Ealing, London, one of the eight children of Mary Ann Hannah (née Trinder - born 1847) and John Hamilton (1839-1884), a master carpenter. Charles Hamilton was privately educated at Thorn House School in Ealing, where he studied Classical Greek among other subjects. He then embarked on a career as a writer of fiction, having his first story accepted almost immediately, appearing in 1895.

Over the following years he was to establish himself as the main writer with the publisher Trapps Holmes, providing several thousand stories on a range of subjects including police, detectives, firemen, Westerns as well as school stories. In 1906 he started to write for the Amalgamated Press and although he continued to have stories published for Trapps Holmes until 1915 (many of which were reprints), his allegiance was gradually to move.

Heyday (1907–1940)
Amalgamated Press started a new story paper for boys called The Gem in 1907 and by issue number 11 it had established a format: the major content was to be a story about St Jim's school, starring Tom Merry as the main character and written by Charles Hamilton under the pen name of Martin Clifford. This paper rapidly established itself and, to capitalise on its success, a similar venture was launched in 1908. This was to be known as The Magnet. The subject matter was a school called Greyfriars and Hamilton was again to be the author, this time using the name Frank Richards.

In 1915 Hamilton started a third school series for Amalgamated Press, Rookwood, this time under the name Owen Conquest and featuring a leading character called Jimmy Silver. These appeared in the Boys' Friend Weekly, and were shorter than the Greyfriars and St Jim's stories.

These three schools absorbed most of Hamilton's energies over the following 30 years and constitute the work for which he is best remembered. In the early part of this period the St Jim's stories were more involved and more popular. The Greyfriars stories, however, evolved gradually over the early years of The Magnet, eventually becoming Hamilton's main priority. His "golden age" is generally regarded as lasting from about 1925 to about 1935. In all he provided stories for 82 per cent of the issues of The Magnet and two thirds of the issues of The Gem. If a Hamilton story was not available, the story was provided by another author but still using the Clifford or Richards name.

By the late 1930s the circulations of both The Gem and The Magnet had declined, partly because of competition from publications by D.C. Thomson. In December 1939 The Gem was cancelled, in the traditional manner of British comics, by being merged with another paper, the Triumph. There is reason to believe that the same fate would have overtaken The Magnet in the summer of 1940, but in the event a sudden shortage of paper, caused by the progress of the war, led to its ceasing publication abruptly and without notice in May that year. The final issue contained the opening story of a new series.

Later career (1940–1961)
Following the closure of The Magnet in 1940 Hamilton had little work, but he became known as the author of the stories following a newspaper interview he gave to the London Evening Standard. He was not able to continue the Greyfriars saga, as Amalgamated Press held the copyright and would not release it. He was obliged to create new schools such as Carcroft and Sparshott, as well as trying the romance genre under the name of Winston Cardew.

By 1946 Richards had received permission to write Greyfriars stories again, and obtained a contract from publishers Charles Skilton for a hardback series, the first volume of which, Billy Bunter of Greyfriars School, was published in September 1947. The series continued for the rest of his life, the publisher later changing to Cassells. In addition, he wrote further St Jim's, Rookwood and Cliff House stories, as well as the television scripts for seven series of Billy Bunter stories for the BBC.

Frank Richards died on 24 December 1961, aged 85, and was cremated at the Kent County Crematorium at Charing in Kent.

Personal life

Hamilton never married, but some details of one romance are provided in a biography, and another is briefly mentioned in his autobiography. Early in the 20th century he was briefly engaged to a lady called Agnes, and later he formed a brief attachment to an American lady whom he alluded to as Miss New York.

His life interests were writing stories, studying Latin, Greek and modern languages, chess, music, and gambling, especially at Monte Carlo. The Roman poet Horace was a particular favourite. He travelled widely in Europe in his youth, but after 1926 he left England only to visit France. He lived in a small house called Rose Lawn, in Kingsgate, a hamlet in St Peter parish, now part of Broadstairs, Kent, where he was looked after by a housekeeper, Miss Edith Hood. She continued to reside in Rose Lawn following his death.

While Hamilton was reclusive in later years, he conducted a prolific correspondence with his readers. He generally wore a skull cap to conceal his hair loss and sometimes smoked a pipe.

He had a close relationship with his sister Una, her husband Percy Harrison and their daughter, Una Hamilton-Wright, who produced her own biography of Hamilton in 2006.

Portraits of Hamilton were painted by the artist Norman Kadish.

Literary output
It has been estimated by the researchers Lofts and Adley that Hamilton wrote around 100 million words or the equivalent of 1,200 average-length novels, making him the most prolific author in history. He is known to have created over 100 schools that were the subjects of his stories as well as writing many non-school stories. More than 5,000 of his stories have been identified, of which 3,100 were reprinted.

Pen-names
At least 25 pen-names have been identified as having been used by Hamilton. These are listed below.

Style and content
Hamilton employed a lightly ironic voice, often studded with humorous classical references which had the effect of making the stories both accessible and erudite. In this respect, he has been compared to P. G. Wodehouse, who emerged from a similar period and was also a prolific author in a light-hearted genre. His extraordinary output has been suggested as arising from a very fluent style that came naturally to him and, in turn made the stories very readable, while at the same time being somewhat wordy.

Much of his popularity derives from his ability to allow the reader to participate vicariously in the ongoing adventure. As with many later children's writers, the stories centred on a small core group of characters who form a close knit unit – at St Jim's there was the Terrible Three, at Rookwood the Fistical Four and at Greyfriars, The Famous Five. Such groups, while being closed to other pupils, are implicitly open to readers who are subliminally invited to include themselves amongst their number, thereby establishing their involvement with the story.

The stories also uphold a moral code of honesty, generosity, respect and discipline, while condemning Hamilton's own weaknesses of smoking and gambling. There is also a strong message against racism in the inclusion of an Indian schoolboy, Hurree Singh, into the core group of the Famous Five in 1908, and by subsequently introducing a Jewish boy, Monty Newland, as a respected member of the Remove (the main form featured in the stories). Both of these 'foreign' characters personify 'British' values of honesty and sportsmanship, and were extremely popular with readers. This attitude did not extend to Africans, however, whom Hamilton describes in racist stereotypes.

Charles Hamilton was a keen gambler at continental casinos before the First World War. Although his stories always had a strong anti-gambling message, such conduct being described as 'sweepy' or 'shady', Hamilton often introduced gambling storylines, such as horserace betting or casinos, and warned of its compulsive dangers.

The moral message throughout is subtly tempered through comic characters, of whom Billy Bunter is the most famous. Bunter is the antithesis of everything the stories value: lazy, greedy, dishonest, and self-centred. However, he is tolerated because of his extreme incompetence and (usually) good nature and lack of malice. His absurd interventions deflate the high seriousness of authority figures, and frequently reduce their efforts to farce.

The public school is a world where adult supervision is light, allowing the juvenile characters to create a society of their own, and dare to adventure beyond the experience of the young readers. This formula became standard in juvenile fiction, though Hamilton's originality and technique were seldom equalled.

Substitute writers
During the 1910s Hamilton's input dropped during his frequent trips to the Continent and the gambling tables of Monte Carlo, and for about 20 years nearly 35 other authors wrote stories for publication under the pen names 'Martin Clifford' and 'Frank Richards'; these included Edwy Searles Brooks (1889–1965), Hedley Percival Angelo O'Mant (1899–1955), William Edward Stanton Hope (1889–1961), Julius Herman (1894–1955) John Nix Pentelow (1872–1931) and George Richmond Samways (1895–1996), the last writing nearly 100 Greyfriars stories among others. Hamilton disparagingly referred to this pool of substitutes as "the Menagerie". The last substitute-written story appeared in The Magnet in 1931; all subsequent stories were solely written by Hamilton.

Criticism
Before World War II, all of Hamilton's writing was for weekly papers, produced on cheap paper and lacking any suggestion of permanence; it had nonetheless attracted a loyal following but, unsurprisingly, no critical attention from the mainstream media. However, there emerged in 1940 a privately printed publication called the Story Paper Collector. This was printed at irregular times in Canada until 1966 when the founder, originally from Croydon, England, died. It was distributed around the world and printed critical discussions and articles about the work of Charles Hamilton and other story paper writers. In November 1946 another magazine, the Collectors' Digest began. Created by Herbert Leckenby, and in due course edited by Eric Fayne and Mary Cadogan, it was to run at mostly monthly intervals until early 2005 (a last issue being published in 2007). Discussion and debates continued through internet based Groups.

An 1940 essay by George Orwell entitled "Boys' Weeklies" paid particular attention to Hamilton's work. Orwell suggested that the style was deliberately formulaic so that it could be copied by a panel of authors whom he supposed to lie behind the Frank Richards name. He denigrated the world of the stories as an outdated, snobbish, and right-wing fantasy, while conceding that Billy Bunter was a "really first-rate character". Hamilton's retort included his first public acknowledgement of himself as author:"In the presence of such authority, I speak with diffidence and can only say that, to the best of my knowledge and belief, I am only one person and have never been two or three." and defended the wholesome comfort of the stories: "A boy of fifteen or sixteen is on the threshold of life: and life is a tough proposition; but will he be better prepared for it by telling him how tough it may possibly be? I am sure that the reverse is the case. . . . Happiness is the best preparation for misery, if misery must come. At least, the poor kid will have had something! He may, at twenty, be hunting for a job and not finding it—why should his fifteenth year be clouded by worrying about that in advance? . . . Even if making miserable children would make happy adults, it would not be justifiable. But the truth is that the adult will be all the more miserable if he was miserable as a child. Every day of happiness, illusory or otherwise—and most happiness is illusory—is so much to the good. It will help to give the boy confidence and hope. Frank Richards tells him that there are some splendid fellows in a world that is, after all, a decent sort of place. He likes to think himself like one of these fellows, and is happy in his daydreams. Mr Orwell would have him told that he is a shabby little blighter, his father an ill-used serf, his world a dirty, muddled, rotten sort of show. I don't think it would be fair play to take his twopence for telling him that!"Cultural historian Jeffrey Richards has written extensively about Hamilton's work, providing many examples of admirers, including John Arlott, Peter Cushing, Ted Willis and Benny Green. He says the works recall a world which contrasts with "the birth of an age which knew all about its rights but had forgotten its responsibilities".

title: Charles Hamilton (writer)


text:
Billy Bunter

William George Bunter is a fictional schoolboy created by Charles Hamilton using the pen name Frank Richards. He features in stories set at Greyfriars School, a fictional English public school in Kent, originally published in the boys' weekly story paper The Magnet from 1908 to 1940. The character has appeared in novels, on television, in stage plays and in comic strips.

He is in the Lower Fourth form of Greyfriars School, known as the Remove, whose members are 14–15 years of age. Time is frozen in the Greyfriars stories; although the reader sees the passing of the seasons, the characters' ages do not change and they remain in the same year groups. Originally a minor character, Bunter's role was expanded over the years with his antics being heavily used in the stories for comic relief and to advance the plots.

Bunter's defining characteristics are his naive greed, self-indulgence, and overweight appearance. He is in many respects an obnoxious anti-hero. Besides his gluttony, he is obtuse, lazy, racist, nosy, deceitful, pompous, and conceited, but he is blissfully unaware of his defects. In his own mind, he is a handsome, talented, and naturally aristocratic young man surrounded by uncouth "beasts". His vices are offset by several redeeming features, including a sporadic but genuine courage in aid of others; his ability to be generous during his rare occasions of prosperity; and above all his very real love and concern for his mother. All these, along with Bunter's irrepressible optimism, and his comically transparent untruthfulness and inept attempts to conceal his antics from his schoolmasters and schoolfellows, combine to make the character highly entertaining, though hardly sympathetic.

Origins
Charles Hamilton invented the character for an unpublished story in the late 1890s. He claimed Bunter was derived from three persons: a corpulent editor, a short-sighted relative, and another relative who was perpetually trying to raise a loan.

The identity of the fat editor is unclear: various sources suggest either Lewis Ross Higgins, editor of a number of comic papers and who is described as resembling the author G. K. Chesterton; or Percy Griffith, the original editor of The Magnet. The short-sighted relative was Hamilton's younger sister Una, who had suffered poor sight since childhood, and who had been wont to peer at him somewhat like an Owl; while the other relative was his older brother Alex, who was described as "generally anxious to borrow a pound or two" on the strength of the anticipated arrival of a cheque that never materialised.

Magnet stories
Billy Bunter featured in 1,670 of the 1,683 issues of The Magnet published during the 32-year period from 1908 to 1940. He was introduced in Magnet No. 1 The Making of Harry Wharton (1908) as a minor character, but developed into one of the principal characters of the stories as author Charles Hamilton realised his comic potential.

George Orwell described him as "...a real creation. His tight trousers against which boots and canes are constantly thudding, his astuteness in search of food, his postal order which never turns up, have made him famous wherever the Union Jack waves."

In addition to stories set at Greyfriars School, he featured in many travel series, with trips to China, India, Egypt, Brazil, Hollywood and the South Seas.

Appearance
In his first appearance, Billy Bunter was introduced thus:

"'The newcomer was a somewhat stout junior, with a broad, pleasant face and an enormous pair of spectacles.'"

Bunter's big round spectacles and rolling gait earned him the nickname the "Owl of the Remove".

In the early stories, both Bunter and classmate Johnny Bull were described as "stout" in appearance; and it was Magnet illustrator C. H. Chapman who first put Bunter into checked-pattern trousers to distinguish the two characters. With the passage of time, the illustrations showed Bunter's circumference ever more pronounced, while Johnny Bull became indistinguishable from the other schoolboys.

A list of the members of the Remove (Lower Fourth) form was published in Magnet No. 1659 Billy Bunter's Bargain (1939), and provided the boys' ages, heights, and weights. Billy Bunter's age is given as 15 years 1 month; his height as 4 ft 9 ins (145 cm); and his weight as 14 stone 121⁄2 lb (94.6 kg).

Character
On many levels, Bunter is deeply unattractive, amply displaying most of the seven deadly sins: pride, wrath, envy, sloth and, most especially, greed and gluttony (though sexual lust is absent in the innocent world of the stories). Bunter is also nosy, deceitful and obtuse. However these traits are softened by his cheery optimism, his comically transparent untruthfulness and his reliable ineptitude when attempting to conceal his antics from his schoolfellows and schoolmasters.

From the very first Magnet story, Bunter suffers an ongoing shortage of cash and is forever attempting to borrow money from his schoolfellows, explaining that he is imminently expecting a postal money order from one of his "titled relations". Over the course of stories spanning several decades, Bunter's celebrated postal order almost never materialises; and the subject becomes a long-running cause of railery in the Greyfriars Remove. Even so, Bunter is a skilful and persistent sponger and succeeds in extracting countless loans from his schoolfellows. Wealthier schoolboys such as Lord Mauleverer frequently part with a few shillings to be rid of Bunter; but even the notoriously tight-fisted American junior Fisher T. Fish is once persuaded to loan him cash.

Bunter's morals are peculiarly his own. He has every intention of repaying his debts, but they end up lingering for months or years. He is obsessed with food – the sweeter and stickier, the better – and is compulsively helps himself to his schoolfellows' sweets, cakes and hampers, for which he earns countless kickings. But despite his complete lack of scruples in such matters, Bunter is otherwise as honest as any other Greyfriars schoolboy. He would never dream of stealing money or valuables.

In the early stories, Bunter was associated with his stammering stock phrase: "I'm s-sincerely sorry". As his character developed, the stammer disappeared, and his stock phrases became his greeting "I say, you fellows!", the reproachful "Oh really, Wharton!" (or whichever character he is addressing), the anguished exclamation "Yaroooh!" and the distinctive giggle "He, he, he!"

Although Bunter has a keen sense of his own importance, this is rarely shared by anyone else. A notable exception occurs in a 1932 story, during an election for a new Remove Form Captain. The support of the form divides equally between two candidates, leaving Bunter with the casting vote, which is keenly solicited by both camps. Bunter becomes the centre of attention, which he exploits to the full. His view of the two candidates illustrates his priorities:

"I'm thinking it out, Toddy," he answered, without moving. "Can't say I like either of the beasts much! Of course, in some ways, Smithy would make a better Form captain than Cherry."

"How do you make that out, fathead—I mean, old fellow!"

"Well, Skinner thinks that if Smithy gets in, a man will be able to dodge games practice without being reported to Wingate."

"Oh crumbs!"

That consideration, evidently, had a strong appeal for Bunter!

"Still, Cherry's not a bad chap in some ways!" said the fat Owl. "He's a good deal more civil than Smithy, if a fellow drops into his study to tea."

"Oh!" gasped Toddy.

"And—he's not reeking with money like Smithy, but, he's a jolly good deal easier to touch for a small loan when a fellow's been disappointed about a postal order," added Bunter thoughtfully.

Peter Todd gazed at him. Bunter evidently had his own original ideas about the qualities that were required in a Form captain!

From The Magnet No. 1258 "Bounder and Captain!" (1932)

In the classroom, Bunter's erudition is slight to non-existent. His extreme laziness and ineptitude is the despair of his Form master, Mr Quelch.

Bunter's personal habits are lazy and slovenly. He is always the last to rise in the morning and always chooses to remain in bed a few extra minutes instead of washing. His handkerchief is permanently filthy, and his waistcoat usually displays remains of his breakfast.

A running theme at the beginning of each holiday season is Bunter's persistent attempts to avoid going home and instead to gatecrash the holidays of his schoolfellows, and their generally unsuccessful attempts to avoid Bunter's company.

He has two talents: for cooking, and an uncanny ability to imitate voices (usually called ventriloquism in the stories). This talent was developed in the early Magnet stories, commencing with Magnet No. 32 The Greyfriars Ventriloquist (1908). In a series of stories in which Bunter unsuccessfully attempts, in turn, a physical exercise regime, hypnotism, and mind reading, a visiting ventriloquism show inspires him to believe himself a born ventriloquist. "More like a born idiot" comments Bob Cherry – but Bunter perseveres and eventually masters the art. It is a talent unappreciated by his schoolfellows, since he generally uses it for mischief, or to get himself out of trouble.

Among Bunter's few virtues is an occasional tendency to display courage for the sake of others, despite his extreme terror on such occasions. This characteristic was first seen in Magnet No. 364 Surprising the School (1915) when he saved his schoolmaster's niece, Cora Quelch, from an angry bull, and was afterwards repeated many times. Unfortunately, Bunter's vanity frequently leads him to spoil matters by boasting and exaggerating afterwards. Oddly enough, he also displays generosity on the rare occasions when he is in possession of food or cash.

Billy Bunter's main redeeming feature is his very genuine love and concern for his mother. This is seen in several stories, usually involving his mother falling ill, which draws out Bunter's unselfish side. (Magnets Nos. 1016, 1206 and 1532).

Bunter as a plot driver
For the first fifteen years of the Magnet stories, Bunter was one of the crowd. From the mid-1920s, as Hamilton increasingly developed Bunter's comic potential, he also began to use his antics to initiate and drive forward the plots.

Conspiratorial conversations or gossip would be overheard by Bunter through a keyhole, or from under the seat in a rail compartment while hiding from the ticket inspector, or under a table hiding from some outraged fellow whose food he had purloined. He would invariably gossip about such knowledge. Letters would be purloined by Bunter and not reach the intended recipient. Bunter's ventriloquism skills would provoke conflicts between other characters. Whilst he was usually not the main protagonist, his influence as a comic interlude and a plot driver was felt at every turn.

In The Secret Seven series of 1934, the entire plotline is initiated by Bunter's stupidity, which causes a road accident that sends a number of leading characters to the hospital.

Bunter as a principal character
During The Magnet era, Billy Bunter is not yet the permanent principal character he would become in the post-war era. Each principal character would take a leading role in turn. Stronger characters such as Remove Captain Harry Wharton, the hard and rebellious Herbert Vernon-Smith, and Fifth form duffer Horace Coker are frequently given leading roles in their own series; and even lesser characters such as American junior Fisher T Fish and aspiring actor William Wibley would occasionally be brought to the fore in their own series.

Eventually, Bunter took his turn with the rest, in a number of stories that placed him as the lead protagonist. Some notable examples include:

 * The Bunter Court series from 1925 (Magnet Nos. 910 to 917) – by a combination of trickery and co-incidence, Bunter manages to obtain the tenancy of a stately home, Combermere Lodge, and passes it off as Bunter Court. Despite the author's comment that this was one of the most contrived plots he had ever been forced to employ, this series is highly regarded. Remarkably, Billy Bunter succeeds in being entertaining without the reader ever being invited to feel the slightest affection or sympathy for him. After borrowing from his guests to pay the servants' wages, and locking the estate agent, the butler, and others into the cellar to hide his tracks, Bunter finally flees before receiving his just desserts.
 * The Whiffles Circus series from 1928 (Magnet Nos. 1069 to 1076) – Billy Bunter assumes the identity of Mr Whiffles, the proprietor of a circus, by stealing his clothes, wig and false whiskers, and sustains the impersonation over the course of the storyline when all the circus hands mistake him for the proprietor.
 * The Bunter £100 Boater Hat series from 1933 (Magnet Nos. 1325 to 1326) – tramp Harold Hinks steals a £100 note belonging to Vernon-Smith's father and hides it under the lining of Bunter's straw hat. However, Bunter is wearing a borrowed hat at the time, leading to Mr Hinks' hapless attempts to recover the banknote by snatching a succession of wrong hats from Bunter's head. Charles Hamilton considered this one of his funniest stories.
 * The Popper Island Rebellion series from 1934 (Magnet Nos. 1374 to 1382) – Billy Bunter is expelled after being wrongfully accused of drenching Fifth Form master Mr Prout in ink. The Remove rise up in his support and build a fortified camp on Popper Island, which they successfully defend against a number of assaults by the prefects and other seniors.

In 1929, the editors of The Magnet persuaded Charles Hamilton to drop the character of Billy Bunter altogether for several editions and attempt a storyline in the style of an action thriller. the Ravenspur Grange series (Magnet Nos. 1122 to 1125). This provoked a strong outcry from Magnet readers dismayed at Bunter's disappearance, and Billy Bunter would never be absent from the stories again.

Racism and chauvinism
Charles Hamilton's writings displayed a pronounced prejudice against Americans. His American characters were either comical or had unsavoury tendencies such as racism or usury. A notable example is Billy Bunter's fellow form member Fisher T. Fish, the son of a New York businessman, whose moneylending frequently brings him into conflict with the school authorities and who, on occasion, displays racist behaviour.

In comparison with contemporary literature, the Greyfriars stories are unusually firm in rejecting racism. Hamilton uses the technique of giving racist dialogue to antihero characters in a way that demonstrates the offensive nature of racist attitudes, including Bunter himself, who often uses language that modern-day readers would characterise as racist.

In an age when the word "nigger" was fairly common, the Greyfriars stories consistently emphasised the offensive nature of the term from as early as 1922 and the narratives even included unfashionable anti-British sentiments in stories set against the background of imperial India.

Family
Billy Bunter has two siblings: a younger sister, Elizabeth Gertrude (Bessie), who attends the nearby Cliff House School, and a younger brother, Samuel Tuckless (Sammy) in the Second Form at Greyfriars School. Bessie first appears in The Magnet No. 582 The Artful Dodger (1919), before appearing as a regular character in The School Friend later that year. Bessie appears in a total of 116 Magnet stories. Sammy Bunter first appears in The Magnet No. 144 Billy Bunter's Minor (1910) and appears in a further 291 Magnet stories.

There is little love lost among the three siblings:

"Bessie was, in Billy's opinion, a cat. Bessie's opinion of Billy could not be expressed so laconically. Her vocabulary on the subject was very extensive indeed.  Only on one subject could Billy and Bessie agree.  That was on the subject of Sammy.  They heartily agreed that Sammy was a little beast."

Their father is Mr William Samuel Bunter, a portly, largely unsuccessful, stockbroker with a severe manner; although it is noted that "like many middle-aged gentlemen, Mr. Bunter was better tempered after breakfast." He is perpetually complaining about income tax and school fees, and is brusque with his children. As often as Billy writes to ask for pocket money, his father refuses. By contrast, Billy is particularly close to his mother, Mrs Amelia Bunter, a kindly lady who appears only briefly in seven stories.

Billy's cousin Walter Gilbert (Wally) Bunter was introduced in Magnet No. 333 The Dark Horse (1914) and appears in a further 32 Magnet stories. He is Billy's exact double, excepting only his spectacles, but is his opposite in every other respect.

Other members of the Bunter family to appear briefly over the years include Billy's uncles James, George and Claude, aunts Prudence and Claribel, great-aunt Eliza Judith, and (in a one-off story) Sir Foulkes Bunter and his son.

Bunter boasts of living at Bunter Court, a stately home with liveried servants and a fleet of chauffeured Rolls-Royce cars. In fact, this turns out to be the modest Bunter Villa in Surrey, with a maid, a cook and a single Ford car.

Reprints
Many stories from The Magnet were reprinted in the Schoolboys Own Library before World War II, and some by Armada and Paul Hamlyn in the 1970s. Most of the 1,683 issues of The Magnet were reprinted in hardback facsimile by publisher W. Howard Baker, under his Howard Baker and Greyfriars Book Club imprints between 1969 and 1990.

Hardback stories
Following the closure of The Magnet in 1940, Hamilton had little work; but he became known as the author of the Greyfriars stories following an interview in the London Evening Standard.

Although he had written many thousands of stories between 1900 and 1940 for the Amalgamated Press, he had used dozens of pen names, and was himself unknown prior to the newspaper article. It was not even widely known that his many pseudonyms represented a single writer.

Hamilton was at first prevented from continuing the Greyfriars saga, as the Amalgamated Press claimed exclusive rights to all the characters except Billy Bunter, who did appear in a Sparshott story in 1946. However, by 1947 they relented, and Hamilton contracted with publisher Charles Skilton for a series of stories to be issued in hardback. The first of these, Billy Bunter of Greyfriars School, illustrated by R. J. Macdonald, was published in September 1947. The series continued for the rest of Hamilton's life. In the 1950s the initial novels were reprinted by Cassells, who continued the series.

Radio
Billy Bunter has been adapted in a radio play several times, the last a 90-minute adaptation of the novel Billy Bunter's Christmas Party on BBC Radio 4 Saturday Night Theatre in December 1986.

In the 1990s, a series of 15-minute dramas adapted from Charles Hamilton's novels were performed by The Goodies (Graeme Garden, Bill Oddie, Tim Brooke-Taylor) for BBC radio.

A radio documentary about the character aired in 1980, on the 40th anniversary of the closure of The Magnet.

Television
Charles Hamilton wrote the scripts for 52 half-hour episodes of the BBC television series Billy Bunter of Greyfriars School, broadcast over seven series between 1952 and 1961, including three specials. The show was centred around Bunter, with other characters in peripheral roles.

Billy Bunter was played by Gerald Campion. The series also featured Anthony Valentine as Harry Wharton, Michael Crawford as Frank Nugent, Jeremy Bulloch as Bob Cherry, Melvyn Hayes as Harold Skinner, John Woodnutt, Raf De La Torre, Kynaston Reeves and Jack Melford as Mr Quelch, Roger Delgado as Monsieur Charpentier and Kenneth Cope as school bully Gerald Loder.

The memorable theme music was the "Portsmouth" section of Ralph Vaughan Williams's Sea Songs. The episodes were transmitted live in black and white, and a dozen still exist in the BBC's archive as telerecordings (see Wiping), including the complete third series of six episodes, one of the specials, one episode from the fifth series, and four from the sixth series.

Stage
Billy Bunter appeared in several Christmas stage shows with different casts:
 * 1958. Billy Bunter's Mystery Christmas (Palace Theatre, London)
 * 1959. Billy Bunter Flies East (Victoria Palace Theatre)
 * 1960. Billy Bunter's Swiss Roll (Victoria Palace Theatre)
 * 1961. Billy Bunter Shipwrecked (Victoria Palace Theatre)
 * 1962. Billy Bunter's Christmas Circus (Queen's Theatre)
 * 1963. Billy Bunter meets Magic (Shaftesbury Theatre)

Comics
After The Magnet closed in 1940, Bunter appeared in children's comics, as a strip cartoon character: initially, from 15 June 1940 in Knockout (which, like The Magnet, was published by The Amalgamated Press). Although Knockout had begun only in 1939, it already had a circulation several times that of The Magnet. C H Chapman, the last illustrator for The Magnet, drew the first nine Knockout strips in 1939, after which several artists were tried, before Frank Minnitt established himself with a beaming and bouncy Bunter, which at first followed Chapman's style, then later branched into a style of his own, concentrating on slapstick humour. Soon the Famous Five vanished from the strip, replaced by Jones minor, who had all the good qualities Bunter lacked, but who was prone to being led astray by Bunter. The form-master, Mr Quelch, stayed (at least in name), but he lost his dignity and aloofness. Minnitt continued producing the strip until his death in 1958. Reg Parlett then took over until Knockout ceased publication in 1961, when the strip transferred to Valiant comic, and then to TV Comic, where it ran until 1984. Bunter also appeared in many Knockout annuals, even on some covers.

C. H. Chapman drew a strip for The Comet comic in 1956, which featured the classical old Bunter of The Magnet and the Famous Five, consisting of twelve weeks of 2-page strips (24 pages in all). Altogether, Bunter's appearances in Comet lasted from March 1950 until June 1958, with picture stories from February 1952.

From 1955, Billy Bunter comic strips were published in the Netherlands, in the Dutch-language comic Sjors, with the character renamed "Billie Turf". Bunter thus became one of the house characters of that comic and its successors, and so continued appearing in anthology-style collections in Dutch until the end of the 20th century. "Billie Turf" comic strip albums were published from 1963 onwards, and have continued into the 21st century. Three Billie Turf movies were made by Henk van der Linden between 1978 and 1983, mostly spelling the name of the main character as "Billy Turf": Billy Turf het dikste studentje ter wereld (1978), Billy Turf Haantje de voorste (1981) and Billy Turf contra Kwel (1982).

Appearances in other fiction

 * Billy Bunter appears in Alan Moore and Kevin O'Neill's graphic novel The League of Extraordinary Gentlemen: Black Dossier, and still resides at the now closed Greyfriars in 1958 as an old man. He sells information about the former students of the school, which is supposed to have been a recruiting ground for spies and agents for the crown since the 16th century. To avoid copyright issues, as the character is still under copyright, the graphic novel only refers to the character by his first name.
 * Bunter appears in the Viz cartoon strip "Baxter Basics" (the title spoofing a slogan of the Conservative Party, "Back to Basics") as Sir William Bunter, Conservative MP for Greyfriars Central. The character was immediately killed off by Baxter, so that he could take over that Parliamentary seat.
 * In Bunter Sahib by Daniel Green, Bunter's identical ancestor is placed in 19th-century India.
 * David Hughes in But for Bunter creates the idea that the Greyfriars stories were based on real people, and set out to find them and hear their stories. This echoed the theme of a contemporary BBC radio documentary, Whatever Happened to... Henry Samuel Quelch.
 * Cyril, a thinly veiled version of Billy Bunter, appears in the Doctor Who story "The Celestial Toymaker". As the character was still under copyright, a BBC continuity announcer was obliged to deny any deliberate similarity between the characters after the episodes aired.

title: Billy Bunter


text:
User:DaveSeidel

My main website is mysterybear.net. I also help operate neurodiversity.com. I am a musician and composer who makes his living writing code.

WP trivia: From 1978-1988, I played with/for Scott Johnson (composer), Lois V Vierk, and Guy Klucevsek, among other "downtown" composers. I was the sole performer on the premiere record of Lois' piece "Go Guitars" (on the CD "SIMOOM", XI Compact Discs 102, 1990), and a member of the ensemble that made the world premiere performance and recording of her piece "Red Shift" (on the CD "River Beneath The River", Tzadik 7056, April 2000). I also appear on one track of Guy's CD "Scenes From A Mirage" (Review Rere 106cdm, 1991).

Fun factoid: did you know that I once seized control of Wikipedia?

title: User:DaveSeidel


text:
Nueva Extremadura

Nueva Extremadura means "New Extremadura" in Spanish, and originates from Extremadura, Spain.

Nueva Extremadura could refer to

 * a large jurisdiction in the north of New Spain, bordered in the 17th century to its west and south by Nueva Vizcaya, by Nuevo León to its southeast; by Nuevo Santander to its east, and, to its northeast, by Louisiana. After 1722, its northeastern border was the New Philippines.  Today many identify the state of Coahuila in Mexico with the former Nueva Extremadura, but the present state's borders are not the same.  For example, Nueva Vizcaya occupied the southwest of present-day Coahuila; Nuevo León, the neighbor to the east, also had claims to eastern New Extremaduran lands; the border with the New Philippines was at the Medina river (near present-day San Antonio, in the U.S. state of Texas).  From 1687, the territory's official name was Provincia de San Francisco de Coahuila y Nueva Extremadura.

 * the name originally given to Chile by Pedro de Valdivia. Its capital was then known as Santiago de Nueva Extremadura.

title: Nueva Extremadura


text:
Southern giant hummingbird

The southern giant hummingbird (Patagona gigas) is one of two species in the genus Patagona and the second largest hummingbird species, after its close relative the northern giant hummingbird.

Taxonomy
The giant hummingbird was described and illustrated in 1824 by the French ornithologist Louis Pierre Vieillot based on a specimen that Vieillot mistakenly believed had been collected in Brazil. The type locality was designated as Valparaíso in Chile by Carl Eduard Hellmayr in 1945. The giant hummingbird was the only species placed in the genus Patagona when introduced by George Robert Gray in 1840.

Molecular phylogenetic studies have shown that the giant hummingbird has no close relatives and is sister to the hummingbird subfamily Trochilinae, a large clade containing the tribes Lampornithini (mountain gems), Mellisugini (bees) and Trochilini (emeralds).

Two subspecies were previously recognised:
 * P. g. peruviana Boucard, 1893 – southwest Colombia to north Chile and northwest Argentina
 * P. g. gigas (Vieillot, 1824) – central, south Chile and west-central Argentina

These subspecies are thought to have emerged as a result of partial geographical separation of populations by volcanic activity in the Andes predating the Miocene; however, there remain areas of contact between the species, hence the lack of full speciation. The proposed phylogenetic system for hummingbirds suggested by McGuire et al. (2009) accommodated the possible elevation of these subspecies to species rank.

In 2014, P. gigas was split into two species, the northern giant hummingbird (P. chaski) and the southern giant hummingbird (P. gigas). The subspecies P. g. peruviana became invalid as it was found to be a nomen dubium. This is because the putative type series for the subspecies includes both giant hummingbird species: one Southern and three Northern giant hummingbirds.

Description
Giant hummingbirds can be identified by their large size and characteristics such as the presence of an eye-ring, straight bill longer than the head, dull colouration, very long wings (approaching the tail tip when stowed), long and moderately forked tail, tarsi feathered to the toes and large, sturdy feet. There is no difference between the sexes. Juveniles have small corrugations on the lateral beak culmen.

Prior to the giant hummingbird being split into the Northern and Southern species, it was described as weighing 18 - 24 g and having a wingspan of approximately 21.5 cm and length of 23 cm. Although the Northern species is larger, both are approximately the same length as a European starling or a northern cardinal, though giant hummingbirds are considerably lighter because it has a slender build and long bill, making the body a smaller proportion of the total length. This weight is almost twice that of the heaviest hummingbird species outside of the genus Patagona and ten times that of the smallest, the bee hummingbird.

The subspecies are visually distinguishable. P. g. peruviana is yellowish brown overall and has white on the chin and throat, where P. g. gigas is more olive green to brown and lacks white on the chin and throat.

The giant hummingbird occasionally glides in flight, a behavior very rare among hummingbirds. Its elongated wings allow more efficient glides than do those of other hummingbirds. The giant hummingbird's voice is a distinctive loud, sharp and whistling "chip".

Distribution and habitat
The giant hummingbird is widely distributed throughout the length of the Andes on both the east and west sides. It typically inhabits the higher altitude scrubland and forests that line the slopes of the Andes during the summer and then retreats to similar, lower altitude habitats in winter months. The species persists through a large altitude range, with specimens retrieved from sea level up to 4600 m. They have shown to be fairly resilient to urbanisation and agricultural activities; however, the removal of vegetation limits their distribution in dense city areas and industrial zones. The giant hummingbird migrates in summer to the temperate areas of South America, reaching as low as 44° S. Correspondingly, it migrates north to more tropical climates in winter (March–August), though not usually venturing higher than 28° S.

' P. g. peruviana ' occurs from Ecuador to the southeastern mountains of Peru and 'P. g. gigas ' from northern Bolivia and Chile to Argentina. Contact between these previously accepted subspecies is most likely to occur around the eastern slopes of the north Peruvian Andes.

Behaviour
Hummingbirds are extremely agile and acrobatic flyers, regularly partaking in sustained hovering flight, often used not only to feed on the wing but to protect their territory and court mates. The giant hummingbird is typical in that it will brazenly defend its precious energy-rich flower territory from other species and other giant hummingbirds. These birds are typically seen alone, in pairs or small family groups.

Flight, anatomy and physiology
The giant hummingbird hovers at an average of 15 wing beats per second, a slow rate for a hummingbird. Its resting heart rate is 300 beats per minute, with a peak rate in flight of 1020 beats per minute. Energy requirements for hummingbirds do not scale evenly with size increases, meaning a larger bird such as giant hummingbird requires more energy per gram to hover than a smaller bird.

The giant hummingbird requires an estimated 4.3 calories of food energy per hour to sustain its flight. This huge requirement along with the low oxygen availability and thin air (generating little lift) at the high altitudes where the giant hummingbird usually lives suggest that it is close to the viable maximum size for a hummingbird.

Food and feeding
The giant hummingbird feeds mainly on nectar, visiting a range of flowers. The female giant hummingbird has been observed ingesting sources of calcium (sand, soil, slaked lime and wood ash) after the reproductive season to replenish the calcium used in egg production; the low calcium content of nectar necessitates these extra sources. Similarly, a nectar-based diet is low in protein and various dietary minerals, and this is countered by consuming insects.

It regularly feeds from the flowers of the genus Puya in Chile, with which it enjoys a symbiotic relationship, trading pollination for food. As a large hovering bird, particularly at high altitudes, the giant hummingbird has extremely high metabolic requirements. It is known to feed from columnar cacti, including Oreocereus celsianus and ''Echinopsis atacamensis ssp. pasacana, and Salvia haenkei''.

Considering the energy-rich nature of nectar as a food source, it attracts a large range of visitors apart from the hummingbird, which has coevolved with a plant to be the flower's most efficient pollinator. These other visitors, because they are not designed to access the well-hidden bounty of nectar, often damage the flowers (for example, piercing them at the base) and prevent further nectar production. Because of its high energy requirements, the giant hummingbird alters its foraging behaviour as a direct response to nectar robbing from other birds and animals, and this reduces the viability of the hummingbird in an area with many nectar robbers, as well as indirectly affecting the plants by reducing pollination. If alien species are introduced that become nectar thieves, it is reasonable to predict that their activities will significantly impact the local ecosystem. This could prove to be a future risk for the giant hummingbird populations because they sit close to the physical limit in their metabolic demands.

Breeding
There is little known of the giant hummingbird's breeding behaviour, but some generalisations can be inferred from other hummingbird species. Hummingbird males tend to have polygynous, occasionally promiscuous, behaviours and no involvement after copulation. The female builds the nest and lays a clutch of two eggs during the summer. A giant hummingbird nest is small considering the size of the bird, typically made near water sources and perched on a branch of a tree or shrub parallel to the ground.

Cultural significance
The giant hummingbird holds significant value for some of the aboriginal inhabitants of the Andes. The people of Chiloé Island believe that if a woman captures a hummingbird then they will gain great fertility from it. This species is a likely inspiration to the people of the Nazca culture who created the Nazca hummingbird geoglyph.

Status
The range of the giant hummingbird is sizable, estimated at 1,200,000 km2, with total numbers of about 10,000 adults. The species is classified by the International Union for Conservation of Nature as being of Least Concern.

title: Southern giant hummingbird


text: User talk:207.15.197.4

title: User talk:207.15.197.4