Thèse Présentée Pour L'

Obtention Du

Titre De Docteur

E N Médecine

Par Nicolas

Segond Thèse

Soutenue Publiquement

Devant Le Jury

Composé De

M Le Pr

Pierre Bouzat

Guillaume Debaty

M Le Dr

Alexandre Bellier

Mme Le Dr Hélène

Duhem M Le Dr

Damien Viglino

DISPOSITIF SUPRA-GLOTTIQUE POUR PRÉVENIR LES INHALATIONS DURANT LA RÉANIMATION CARDIO-PULMONAIRE PAR LES SECOURISTES : ÉTUDE RANDOMISÉE EN CROSS-OVER SUR DES CADAVRES HUMAINS

Supraglottic airway device to prevent pulmonary aspiration during cardio-pulmonary resuscitation by basic life support rescuers: a randomized cross-over human cadaver study

Nicolas Segond

AVERTISSEMENT

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Contact à la Bibliothèque universitaire de Médecine Pharmacie de Grenoble : bump-theses@univ-grenoble-alpes.fr « Le but de la vie, c'est de s'épanouir. Réaliser à la perfection notre propre nature, voilà pourquoi chacun d'entre nous oublie le plus important de ses devoirs : le devoir envers soi »

Oscar Wilde, Le portrait de Dorian Grey « Être homme, c'est précisément être responsable. C'est sentir, en posant sa pierre, que l'on contribue à bâtir le monde ». for advance life support [START_REF] Perkins | European Resuscitation Council Guidelines 2021: Executive summary[END_REF][START_REF] Panchal | Part 3: Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care[END_REF] . Endotracheal intubation was considered as the gold standard to protect airways 6 but the more effective early airway device during CPR is still debated [START_REF] Jabre | Effect of Bag-Mask Ventilation vs Endotracheal Intubation During Cardiopulmonary Resuscitation on Neurological Outcome After Out-of-Hospital Cardiorespiratory Arrest: A Randomized Clinical Trial[END_REF][START_REF] White | Advanced airway management in out of hospital cardiac arrest: A systematic review and meta-analysis[END_REF][START_REF] Wang | Comparing Effectiveness of Initial Airway Interventions for Out-of-Hospital Cardiac Arrest: A Systematic Review and Network Meta-analysis of Clinical Controlled Trials[END_REF][START_REF] Wang | Effect of a Strategy of Initial Laryngeal Tube Insertion vs Endotracheal Intubation on 72-Hour Survival in Adults With Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial[END_REF][START_REF] Benger | Effect of a Strategy of a Supraglottic Airway Device vs Tracheal Intubation During Out-of-Hospital Cardiac Arrest on Functional Outcome: The AIRWAYS-2 Randomized Clinical Trial[END_REF] .

Among patients admitted in intensive care units after cardiac arrest, almost 60% will present an early onset pneumonia [START_REF] Perbet | Early-onset pneumonia after cardiac arrest: characteristics, risk factors and influence on prognosis[END_REF] . Early onset pneumonia after cardiac arrest doesn't seem to increase mortality neither to modify neurologic prognosis but increases intensive care unit length of stay up to four days by average and hospital's cost [START_REF] Perbet | Early-onset pneumonia after cardiac arrest: characteristics, risk factors and influence on prognosis[END_REF][START_REF] Pabst | Predictors and outcome of early-onset pneumonia after out-of-hospital cardiac arrest[END_REF] . Early antibiotics use can prevent early onset pneumonia [START_REF] François | Prevention of Early Ventilator-Associated Pneumonia after Cardiac Arrest[END_REF] but there is no documentation about the influence of early advanced airway control. Moreover, early advanced airway control might help to spare antibiotics, who is one of major global health issue.

In France, the majority of basic life support rescuers are trained volunteers. They are the first responders after bystanders and they provide advanced life support before emergency medical service. They usually use bag-mask ventilation (BMV) to ventilate patients during CPR. Ventilation with BMV could be more difficult for inexperienced providers than supraglottic airway devices (SGA) [START_REF] Hart | Efficacy of Laryngeal Tube versus Bag Mask Ventilation by Inexperienced Providers[END_REF] . Moreover, learning to use SGA seem easy even for nonmedical staff [START_REF] Lemaitre | Effectiveness of Intubating Laryngeal Mask Airway in managing out-of-hospital cardiac arrest by non-physicians[END_REF][START_REF] Schalk | Out-of-hospital airway management by paramedics and emergency physicians using laryngeal tubes[END_REF][START_REF] Bielski | Comparison of blind intubation with different supraglottic airway devices by inexperienced physicians in several airway scenarios: a manikin study[END_REF][START_REF] Tritsch | Intubating laryngeal mask airway placement by non-physician healthcare providers in management out-of-hospital cardiac arrests: a case series[END_REF] . SGA could prevent aspiration of gastric content if placed early in the management of cardiac arrest as the first line airway device [START_REF] Stone | The incidence of regurgitation during cardiopulmonary resuscitation: a comparison between the bag valve mask and laryngeal mask airway[END_REF] . We hypothesized that early use of SGA by basic life rescuers could reduce pulmonary aspiration in a human cadaver CPR model. The objective of this study was to assess the impact of SGA on pulmonary aspirations, insufflation success rate and intragastric pressure.

METHODS

Study design

This

Human cadavers

Human bodies used in this study were donated for medical science by donators themselves. Written and witnessed consent to donate their bodies to science for anatomical and pedagogical purposes was given prior to death. This donation was free, anonymous and regulated by the French funeral legislation. All interventions were performed in the LADAF.

All cadavers received the same preparation. They were embalmed with formol and preserved at 4°C. Each cadaver was out of the cold room at least 4 hours before intervention to warm it. Cadavers were excluded if they presented obvious upper airway damage as tumors or traumatisms, if they had an history of epigastric surgery or if the BMI were > 45 kg/m 2 .

The cadaver was intubated to protect airways during the preparation of stomach. A fiberoptic bronchoscopy was performed to eliminate any bleeding or aspiration in the upper and lower airways. Bronchoscopy was realized with Ambu® aScope™ 4 Broncho Regular endoscope and with Ambu® aView™ monitor. A 16CH double lumen Foley catheter was inserted in the stomach through a 2 mm incision. The balloon was inflated with 30 mL of serum saline solution. A gastric suture was made around the Foley catheter to fix and seal it.

Abdominal wall was then sutured. An urinary collection pocket was connected to the Foley catheter and a 20G catheter was introduced into the collection membrane. An hydrostatic pressure sensor was connected to this catheter to measure gastric pressures.

Basic life rescuers

Volunteers basic life rescuers were recruited into French first aid associations

(

Airway control

SGA used in this study were adult i-gel ® (Intersurgical ® , UK). Three adult sizes (3, 4, 5) were available and were chosen by the rescuer himself before the 5 min standard CPR. They didn't use the gastric channel. Ventilation through i-gel ® was made with an Ambu ® SPUR ® II Resuscitator.

BMV was assured with an Ambu® UltraSeal face mask and an Ambu® SPUR® II

Resuscitator. Three face mask sizes (little, medium, large) were available and were chosen by the rescuer himself before the 5 min standard CPR.

CPR standardization

In this study, each 5 min standard CPR was performed by a 4 rescuers team according to international guidelines 1,5 . CPR was performed at a ratio of 30 compressions and 2 insufflations. Chest compression rate was 100 to 120 per minute and compressions with a targeted depth of at least 5 cm but not more than 6 cm, according to international guidelines.

Relays between rescuers were made every 2 minutes to keep a good CPR efficiency. One rescuer was awarded to control airways with SGA or BMV. He was not allowed to switch role before the first success insufflation. After the first success insufflation, head rescuer could change his place if it was necessary. We ordered rescuers to inflate carefully and slowly around 1 second per insufflation.

Experimental protocols

Protocol A

In this protocol, the objective was to assess pulmonary aspirations. They were defined as the presence of colored blue or green serum saline solution below the vocal cords.

After cadaver intubation to protect airways, we filled cadaver's stomach with 300 mL randomized colored blue or green serum saline solution. Serum saline solution was prepared with a food color additive at dilution of 3%. After the cadaver's extubation, 5 min standard CPR was started with a randomized SGA or BMV. At the end of the 5 min standard CPR, we assessed pulmonary aspiration by fiberoptic bronchoscopy by a blinded operator. Serum saline solution presented in respiratory tree was aspirated by the fiberscope as much as possible to prepare the second intervention. The cadaver was intubated again. In a cross-over design, the stomach was then emptied and filled with the second 300 mL colored serum saline solution with another 5 min CPR period using the other airway method. At the end of the 5 min standard CPR, pulmonary aspiration was assessed by fiberoptic bronchoscopy by the same blinded operator.

Protocol B

In this protocol we assessed insufflation success rate, gastric pressure and CPR time points and intervals.

Insufflation success rate was defined as an elevation of thorax after an insufflation as recommended in guidelines. All CPR metrics were controlled by a second operator with CPR videos.

For each cadaver, protocol A and B were performed in parallel for the two first 5 min standard CPR. Protocol B was pursued if the state of cadaver body allowed it as shown in Figure 1.

Statistical analysis

Continuous variables were described as mean +/-standard deviation (SD); minimum and maximum for normal distribution or median and interquartile range (IQR) in the case of skewed distribution. Qualitative variables were described as numbers and percentages of modalities.

In protocol A, a generalized linear mixed model was performed, taking into account cadavers as a random effect and period and ventilation strategy-by-period interaction as fixed effects.

The analysis of protocol B outcomes was performed using a generalized linear mixed model for continuous quantitative dependent variables, following a similar strategy to that used for protocol A. For survey answers, a binomial test was performed to compare one sample proportions. The statistical significance level was set at 0.05 in bilateral situations for all comparison tests, without adjustment of the P-value related to the multiplicity of tests. The point estimates was framed by a 95% confidence interval. All statistical analyses were performed using Jamovi® (Version 1.6.23.0) with the GAMLj (General Analyses for linear model) package.

RESULTS

Baseline characteristics

A total of 48 rescuers were enrolled in this study. 20 participated in protocol A and 48 in protocol B (Table 1). A total of 11 cadavers were included in this study (Table 2). 10 cadavers were included in protocol A to perform 20 CPR and 11 cadavers in protocol B to perform 48 CPR. One cadaver was excluded of protocol A due to hemoptysis not seen during preparation, leading to an impossible fiberoptic bronchoscopy (Figure 2). second for an optimal mouth pressure. If insufflation time is lower, insufflated pressure and gastric insufflation are higher [START_REF]Fast or Slow Rescue Ventilations: A Predictive Model of Gastric Inflation[END_REF][START_REF] Von Goedecke | Effects of decreasing peak flow rate on stomach inflation during bag-valve-mask ventilation[END_REF][START_REF] De Regge | Retention of ventilation skills of emergency nurses after training with the SMART BAG compared to a standard bag-valvemask[END_REF] . That's why we ordered our rescuers to inflate carefully and slowly around 1 second per insufflation. Lower esophageal pressure is an important factor to predict gastric insufflation and aspirations because it decreased during cardiac arrest and pulmonary resuscitation [START_REF] Gabrielli | Lower Esophageal Sphincter Pressure Measurement during Cardiac Arrest in Humans: Potential Implications for Ventilation of the Unprotected Airway[END_REF] but we chose to not put a pressure sensor through the mouth and in airways to not disturb rescuers during CPR. Finally, we chose to fill cadaver's stomach with a 300 mL of serum saline solution while other studies filled cadaver's stomach with a volume of 500 mL [START_REF] Piegeler | Evaluation of six different airway devices regarding regurgitation and pulmonary aspiration during cardio-pulmonary resuscitation (CPR) -A human cadaver pilot study[END_REF][START_REF] Ruetzler | Regurgitation and pulmonary aspiration during cardio-pulmonary resuscitation (CPR) with a laryngeal tube: A pilot crossover human cadaver study[END_REF]

All

Limitations

This study has several limits. First, cadaver models heterogeneity is an important limitation to generalize studies results. Cadaver models have been described as relevant for pathophysiological studies in cardiac arrest [START_REF] Duhem | Cadaver models for cardiac arrest: A systematic review and perspectives[END_REF] . Thiel embalmed cadavers represent the most efficient model to study ventilation in cardiac arrest due to his property to preserve elasticity and flexibility of tissues that were found to be comparable to values reported in critically ill patients [START_REF] Duhem | Cadaver models for cardiac arrest: A systematic review and perspectives[END_REF] . Unfortunately Thiel-embalmed cadavers are rarely available. In the current study we used low concentration formalin-embalmed cadavers. Although some limitations due to this preparation like some rigidity of tissue 37 , all of our cadavers were recently prepared with a mean of 19 days post mortem utilization and were warming up before utilization in order to limit rigidity. Pulmonary compliance did not seem affected by our model. Second, cadavers in protocol B don't have the same number of participation. We explain this by cadavers intrinsic characteristics especially their robustness and by the fluctuating cadaver's availability.

Generalized linear mixed model including both fixed and random effects was chosen to limit this bias. Cadavers were taken into account as random effect and intervention as fixed effect to take into account that variability of use. Third, rescuers were alone to control airway with SGA and BMV that's could change their daily practices. Recent guidelines due to Covid-19 context advise to ventilate at 4 hands with BMV to improve mask sealing. It's more simple for rescuers to ventilate at 4 hands with BMV but with SGA only one rescuer is necessary to control airways and probably for the same sealing. We chose to let one rescuer control airway in the two groups to ensure group comparability. Fourth, chest compressions and rescue breaths were realized in a ratio of 30:2 in the two groups. International and European recommendations about basic life support advise to not interrupt chest compressions when an advanced airway control is used (SGA or endotracheal intubation) [START_REF] Perkins | European Resuscitation Council Guidelines 2021: Executive summary[END_REF][START_REF] Panchal | Part 3: Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care[END_REF] . In a similar approach to our study, some studies suggest that continuous chest compressions compared to interrupted compressions with a 30:2 ratio reduce the volume gas insufflated in the stomach [START_REF] Savary | Gastric insufflation during cardiopulmonary resuscitation: A study in human cadavers[END_REF][START_REF] Segal | Effect of continuous oxygen insufflation on inducedgastric air volume during cardiopulmonary resuscitation in a cadaveric model[END_REF] . We chose to keep a 30:2 ratio in the two groups because our French rescuers don't routinely use an advanced airway device without medical staff and to preserve group comparability. Moreover, it was more simple to assess intragastric pressure because we could see with precision gastric insufflation without chest compression. However, this choice can limit study external comparability and generalization.

Fifth, it's important to highlight that rescuers were evaluated with only SGA or BMV. They are not their own control, this can train a comparability bias. In our point of view, if they were evaluated on both SGA and BMV they could probably favor one of them. With this study design, they were random to use SGA or BMV one time, they had to give the best of themselves during the only one evaluation. Sixth, we couldn't measure total gastric volume during a 5 min standard CPR like in other studies [START_REF] Savary | Gastric insufflation during cardiopulmonary resuscitation: A study in human cadavers[END_REF][START_REF] Segal | Effect of continuous oxygen insufflation on inducedgastric air volume during cardiopulmonary resuscitation in a cadaveric model[END_REF]

  Each 5 min standard CPR were filmed and insufflation success rate was assessed and controlled with CPR videos. Rescuers received the instructions to raised their hands during insufflation to allow clear visualization of thorax elevation. If hands were left on cadaver thorax or if there was any doubt on thorax elevation, insufflation was assessed as failed.Gastric pressures were assessed with a hydrostatic pressure sensor through gastric foley catheter as described previously. Pressures were assessed with a PowerLab 4/26 series (ADInstrument Pty Ldt) and Labchart software (ADInstrument Pty Ldt, 2000-2014) and were expressed in mmHg. The aim was to measure gastric pressure during insufflation to reflect gastric insufflation. An operator was dedicated to control and note gastric pressures during insufflations. They were controlled with Labchart software by a second operator in post-hoc analysis. During a 2 insufflations period we retained the maximal gastric insufflation pressure.Then, during a 5 min standard CPR we calculated mean gastric pressure, maximal gastric pressure and differential gastric pressure who was defined as maximal gastric pressure minus minimal gastric pressure.CPR time points and intervals showed us if the introduction of a new airway device affect essential times of basic life support resuscitation. An operator was dedicated to assess during 5 min standard CPR time points to: recognize cardiac arrest; to start resuscitation; to place automated external defibrillator (AED); to start introduction of airway device; to first efficient insufflation; to first and second AED shock and the total no-flow duration. We also calculated the interval between the introduction of airway device and first efficient insufflation.

Fig. 1 -

 1 Fig. 1 -Study experimental protocols

Fig. 4 -

 4 Fig. 4 -Numerical scales survey answers

MF : Masque Facial Supraglottic airway device to prevent pulmonary aspiration during cardio-pulmonary resuscitation by basic life support rescuers: a randomized cross-over human cadaver study.

  Antoine de Saint-Exupéry, Terre des Hommes REMERCIEMENTS M. le Pr Pierre BOUZAT, vous me faites l'honneur de présider ce jury et de juger ce travail de thèse. Vous m'avez aussi permis de réaliser un stage libre en anesthésie au cours de mon internat, stage qui m'a beaucoup apporté. Pour tout cela, je vous remercie. M. le Pr Guillaume DEBATY, merci d'avoir accepté de diriger ce travail de thèse. Tu m'as permis de transformer une idée en un vrai travail de recherche expérimentale. Je te remercie pour ton soutien, ta patience et tes réponses à mes multiples questions lors de la réalisation de ce projet. Cela m'a énormément apporté et je suis sûr que les projets à venir seront tout aussi enrichissants. Philippe, pour sa disponibilité, son dévouement, pour la préparation des corps, sa pédagogie, mais aussi pour sa bonne humeur sans faille, A Caroline et Olivia qui sont venues à chaque séance m'aider à recueillir les données, à encadrer les secouristes lors des RCP et me soutenir lors de ces journées éprouvantes, Au Dr François-Xavier KOCH qui m'a conseillé et aidé sur le versant pédagogique, pour sa disponibilité et son soutien, je te remercie vivement et te suis très reconnaissant de m'avoir initié à la pédagogie médicale et de m'avoir inclus dans la formidable équipe du CESU, Merci aux internes qui sont passés avec moi aux Urgences du CHU de Grenoble au 1 er semestre (Maxime et Maxime, Aline, Lucile, JT, Chloé, Adrien, Thibault, Emilie et les urgentistes de ma promo), un semestre et une ambiance que nous n'oublierons pas ! A Laurine, avec qui j'ai réalisé la moitié de mon internat, merci pour ta bonne humeur, ton soutien de tous les instants et tous ces bons petits plats que nous avons partagés. A Rémi, avec qui on a formé le trio de choc à Voiron, merci pour tous ces fous rires, tu resteras notre cardiologue préféré. A mes co-internes d'anesthésie, Ophélie, Benjamin et Benoît, merci de m'avoir accueilli dans ce monde hostile qu'est le bloc opératoire et pour ces belles journées au lac d'Annecy.

	A Denis et Alexandre, nous nous suivons maintenant depuis bientôt 10 années, de cette LISTE DES ABREVIATIONS
	rencontre est née une amitié profonde et sincère. Merci d'avoir été là dans les meilleurs
	moments comme dans les plus compliqués, vous m'avez soutenu dans toutes les circonstances CPR: cardiopulmonary resuscitation
	et avez ouvert mon champ des possibles. Je vous en remercie vivement. SGA: supraglottic airway device
	BMV: bag mask valve
	A Dimitri et Maëva, mes amis de toujours qui, malgré la distance et des chemins de vie AED : automated external defibrillator
	entièrement différents, m'ont soutenus durant toutes ces années. SD : Standard Deviation
	IQR : Interquartile Range
	A ma famille, à ma mère, mon père, mon frère Mathieu, ma soeur Amélie, mes grands-
	parents, vous me soutenez sans relâche depuis mon plus jeune âge dans toutes les étapes de ma
	vie, vous m'avez sans cesse tiré vers le haut, vous m'avez donné une éducation solide et robuste RCP : Réanimation Cardio-Pulmonaire
	qui m'a permis de réaliser ce que j'ai toujours voulu faire. Sans vous, je ne serai pas l'homme DSG : Dispositif Supra-Glottique
	que je suis aujourd'hui.
	Enfin, je tiens à remercier avec tendresse la femme qui partage ma vie avec amour
	Merci à tous mes collègues des Urgences et du SAMU de Grenoble ainsi que tous les depuis maintenant 6 années, Thao. Tu as été mon soutien au quotidien, nous avons surmonté
	médecins croisés sur ma route qui m'ont vu grandir tout en me transmettant leur savoir, je vous ensemble, main dans la main, toutes les épreuves de ces dures études. Nous avons accompli de
	en suis extrêmement reconnaissant. belles choses, vécu des instants magnifiques, je ne demande qu'à continuer à vivre avec toi tous Key words : supraglottic airway device, bag-valve mask, cardiac arrest,
	les instants que nous donne la vie.
	pulmonary aspiration, basic life support, rescuers, cardiopulmonary resuscitation,
	A mes amis marseillais rencontrés durant l'externat, Katia, Kristel, Laura, Nathalie,
	Caroline et Morgane, nous avons évolués ensemble et nous voilà bientôt tous médecins, merci human cadaver
	pour tous ces moments passés avec vous et pour ceux à venir.
	A Isis, Adrien et Santa, merci à vous pour tout ce que nous avons vécu ensemble, pour
	votre soutien indéfectible durant ces études, les sous-colles, les écuries, les révisions mais aussi
	les vacances inoubliables, du ski au VTT en passant par les montagnes et les magnifiques
	paysages Corses.

M. le Dr Alexandre BELLIER, tu m'as accueilli à bras ouvert dans ce milieu si particulier qu'est le laboratoire d'anatomie. Je te suis grandement reconnaissant pour ta présence et ton soutien sans failles. En plus de m'avoir aidé à disséquer et à préparer chaque corps, ton aide dans la réalisation des statistiques de cette étude a été décisive. Sans cela je n'aurai pu mener à bien ce projet. Pour tout, je te remercie sincèrement. Mme le Dr Hélène DUHEM, tu m'as guidé, conseillé et soutenu tout au long de ce projet. Ta disponibilité, ton expérience et tes connaissances dans la recherche sur l'arrêt cardiaque m'ont été d'une grande aide. Je te remercie de me faire l'honneur de juger ce travail. M. le Dr Damien VIGLINO, tu me fais le plaisir et l'honneur de juger ce travail. Je te suis très reconnaissant pour tes relectures et les nombreux conseils que tu m'as apporté au cours de ce projet. Je te remercie aussi, en tant de coordonnateur du DES, d'éveiller notre curiosité et de nous mener vers l'excellence. J'adresse des remerciements chaleureux à toutes les personnes sans qui, cette étude n'aurait pu être menée à bien : A A tous les secouristes qui ont pris une journée de disponibilité pour venir travailler avec nous et partager leur expérience, A Sébastien Deutsch qui m'a aidé à trouver un nombre de secouristes conséquent en un temps limité, cette aide décisive m'a permis de mener à bien ce projet, je t'en remercie, Au Dr Marc Blancher, pour son aide dans le recrutement des secouristes du PGHM et les CRS, A Laurine et Déborah, qui ont pris de leur temps avec Hélène pour venir réaliser les fibroscopies bronchiques en aveugle, merci pour votre patience, Au Pr Philippe CHAFFANJON, merci de m'avoir accueilli au LADAF et d'avoir soutenu ce projet. Je tiens à remercier ma promotion du DES de Médecine d'Urgence, promotion des Aiguilles Rouges avec qui j'ai passé un magnifique internat. Alice, Camille, Laura, Justine, Antoine, Julien, Lucile, Déborah, Céline, Laurène, Laurine et Simon, nous sommes tous devenus des amis et formons maintenant un groupe soudé, encore merci à vous.

A mes co-internes de la réanimation à Chambéry, Florian, Marine, Diana, Léa et Gauthier, merci pour ce beau semestre avec vous qui n'est pas encore terminé ! A Jean-Baptiste, merci pour toutes ces sorties, de m'avoir initié à la montagne et d'avoir perfectionné ma technique en ski, A Laura, que j'ai eu le plaisir de connaître et de suivre comme externe et qui maintenant va devenir interne, courage à toi pour la suite,

TABLE DES MATIERES

 DES RESUME ............................................................................................................. ABSTRACT ........................................................................................................ INTRODUCTION ............................................................................................... METHODS .......................................................................................................... La pression intragastrique ainsi que la pression intragastrique différentielle étaient diminuées dans le groupe DSG : 2.21 mmHg (1.66 ; 2.68) vs. 3.02 (2.02 ; 4.22), p = 0.017 ; et 5.70 (4.10 ; 7.60) vs. 8.05 (5.40 ; 11.60), p = 0.046. Les délais clés durant la RCP n'étaient pas significativement différents entre les deux groupes. During CPR, using a SGA by first rescuers improved insufflation success rate, decreased intragastric pressure and did not affect key CPR metrics. A non-significantly lower rate of aspiration was observed with SGA in this small study based on cadaver model of cardiac arrest. The annual incidence of out-hospital cardiac arrest (OHCA) in Europe is between 67 to 170 per 100,000 inhabitants 1 . It affects 350 000 people in the United States 2 and 46 000 people in France 3 each year. The global survival rate in Europe is around 8% 1 . This makes it one of major public health issues. Early initiation of bystander cardio-pulmonary resuscitation (CPR), advanced life support by rescuers and emergency medical services are keys to favorable outcome. Airway management is crucial and adequate ventilation and oxygenation are essentials to preserve tissues oxygenation and probably to raise returns to spontaneous circulation 4 .

	Conclusion : Durant la RCP, l'utilisation d'un DSG par des secouristes augmente le taux de
	réussite des insufflations et diminue les pressions intragastriques sans affecter les délais clés de
	la RCP sur un modèle cadavérique expérimental d'arrêt cardiaque. Une diminution non
	significative du taux d'inhalation a été observée avec les DSG.

RESULTS ............................................................................................................ DISCUSSION ..................................................................................................... CONCLUSION ................................................................................................... CONFLICT OF INTEREST ............................................................................... RESUME Introduction : Les inhalations pulmonaires de contenu gastrique sont fréquentes lors de la réanimation cardio-pulmonaire (RCP) d'un arrêt cardiaque. L'intubation orotrachéale est le gold-standard pour protéger les voies aériennes mais les dispositifs supra-glottiques (DSG) pourraient offrir une protection similaire et nécessiter moins d'apprentissage. La ventilation au masque facial (MF) est la méthode habituellement utilisée par les secouristes. Nous faisons l'hypothèse que l'utilisation précoce d'un DSG par les secouristes pourrait diminuer les inhalations pulmonaires en utilisant un modèle cadavérique d'arrêt cardiaque. Méthodes : protocole A : après une séance de 3 heures d'entraînement, chaque secouriste est randomisé pour utiliser un DSG (i-gel ® ) ou un MF durant une RCP standardisée de 5 minutes. Une sonde urinaire a été introduite dans l'estomac de pièces cadavériques pour le remplir de 300 mL d'une solution saline colorée bleue ou verte de façon randomisée. Sur un modèle en cross-over, l'estomac est ensuite vidé et rempli à nouveau par l'autre solution saline colorée et une nouvelle RCP de 5 minutes est débutée avec l'autre dispositif de gestion des voies aériennes. L'inhalation pulmonaire était définie par la présence de la solution saline colorée endessous des cordes vocales et a été recueillie par fibroscopie pulmonaire par un opérateur en aveugle. Protocole B : pour chaque RCP de 5 minutes, nous avons recueilli le taux de d'insufflations réussies, les pressions intragastriques et les délais clés durant la RCP (début de la RCP, 1 ère défibrillation, durée de no-flow). Un modèle généralisé mixte a été utilisé pour les analyses statistiques. Les données sont présentées par des n (%) et des médianes (IQR 25 -75). Résultats : Dans le protocole A, dix corps ont été inclus pour réaliser vingt RCP. Les inhalations sont survenues pour 2 (20 %) des corps dans le groupe DSG et pour 5 (50 %) des corps dans le groupe MF, p = 0,44. Dans le protocole B, quarante-huit secouristes ont été inclus pour réaliser quarante-huit RCP sur onze corps. Le taux de réussite des insufflations était plus élevé dans le groupe DSG que dans le groupe MF : 75.0% (25.0 ; 50.0) vs. 34.7% (59.8 ; 87.3), p = 0.003. Conclusion: INTRODUCTION Current guidelines suggest using bag mask ventilation or an advance airway during CPR

  experimental study was randomized, controlled with two cross-over arms and two different experimental protocols comparing BMV and SGA during cadavers CPR. This study carried out between February 16 th 2021 and April 30 th 2021 during six entire days in the LADAF (Laboratoire d'Anatomie des Alpes Françaises/French Alps Anatomical Laboratory) located in Grenoble Medical School.

	Randomization was performed before study intervention with R software (version 4.0.3
	(2020) -the R foundation for statistical computing) with block size of 2 rescuers to receive
	SGA or BMV in a 1:1 ratio.

  Fédération Française de Sauvetage et de Secourisme/French Federation of Rescue and First Aid (FFSS), Croix Rouge Française/French Red Cross (CRF) and Protection Civile or BMV, whether ventilation seemed more efficient with SGA or BMV and if SGA seemed too long to introduce. Finally, we asked them with a 0 to 10 numerical scale how SGA was easy to use (0 = difficult ; 10 = easy) and whether SGA daily use was feasible (0 = unrealizable ; 10 = feasible). All questions were assessed and validated by a panel of CPR expert and pedagogy expert. A translate version of the survey is available in appendix.

	Basic life rescuers training
	Each rescuer received a 3 hours training session to use SGA. The training, who was
	performed by an experiment emergency medicine physician for a ten rescuers group, included
	a one hour lesson to explain the study and how to use SGA, a one hour practical lesson to
	discover SGA and how to introduce it on a head manikin and one hour practical lesson to
	perform manikin CPR with SGA. The objective of this training session was to perform three
	success insufflations with SGA on a manikin. After the training, rescuers were included in

Française/French Civil Protection (PCF)). Professional basic life rescuers were recruited into mountain rescue units (Peloton de Gendarmerie de Haute Montagne/High Mountain Gendarmerie Platoon (PGHM) and Compagnies Républicaines de Sécurité/Republican Security Company (CRS)). They were all trained in first aid and basic life support as the French recommendations. They were excluded if they had less than 3 years of experience, if they were not up to date with their training lessons and if they were healthcare professionals. They all consent to participate in the study. cadavers CPR model. After receiving the training session and cadavers CPR experiment, rescuers were asked to fill a five question survey. Questions evaluated whether it was easier to ventilate with SGA

Table 1 -

 1 Rescuers population characteristics

	Sex
	Male	31 (64.6 %)	17	14
	Female	17 (35.4 %)	7	10
	Status
	Professional	13 (27.1 %)	17	18
	Volunteer	35 (72.9 %)	7	6
	Corporation
	FFSS	22 (45.8 %)	12	10
	Croix Rouge Française	9 (18.8 %)	4	5
	Protection Civile	4 (8.3 %)	1	3
	PGHM	9 (18.8 %)	4	5
	CRS	4 (8.3 %)	3	1

Table 2 -

 2 Cadavers population characteristicsData are expressed as mean +/-Standard Deviation (Min -Max)

	Fig. 2 -Flowchart

Table 5 -

 5 Survey answers

  . In this study, we used a foley catheter to fill and empty cadaver's stomach. Foley catheter balloon was inflated with a 30 mL of serum saline solution that's take off stomach volume. In preliminary tests, regurgitations were massive with 500 mL of serum saline solution maybe due to a reduced gastric volume by Foley catheter. With 300 mL serum saline solution, aspirations are not systematic like in current practice[START_REF] Simons | The incidence and significance of emesis associated with out-of-hospital cardiac arrest[END_REF] . We made this choice to be close as possible to what is observed in real CPR resuscitation. Cadavers were their own control in this study to ensure intrinsic comparability and in protocol A all cadavers were used only two times with two colorants with SGA and BMV. Pulmonary aspirations were assessed by a blinded operator. Moreover, each 5 minutes standard CPR were filmed to control by a second operator insufflation success rate and CPR time points. This study design comfort our results.

	Taking into account rescuers' feelings about SGA and BMV use after a one training day
	was one of our objectives. Answers largely favors SGA compare BMV. We can explain this by
	introducing a new equipment for rescuers can generate enthusiasm and modify their judgement.
	But answers absolutely show ease and efficiency of SGA's use in this population.
	Although it's an experimental cadaver study, we designed this study as a prospective
	randomized cross-over control study. Randomization ensures SGA and BMV group
	comparability.

CPR time points and intervals assessment were not different between the two groups. It was important to see if the introduction of an advanced airway control approach in the rescuer's population modified CPR time points and intervals. In fact, basic life support primary objectives are chest compressions and defibrillation. Our key CPR metrics includes this primary goals and also time between airway device introduction and first efficient ventilation. They were confirmed posteriorly by CPR videos by a second operator to ensure results quality.

  . We measured only gastric pressures which reflect gastric volume during CPR.CONCLUSIONUsing a supraglottic airway device by first rescuers improved insufflation success rate and decreased intragastric pressure without affect CPR metrics in a cadaver model of cardiac arrest. A non-significantly lower rate of aspiration was observed with SGA. SGA use by basic life rescuers is feasible and appear efficient. SGA could play an important future role in first part of cardiopulmonary resuscitation. Further clinical studies are needed to assess SGA clinical implications.

ACKNOWLEDGMENTS ................................................................................... REFERENCES .................................................................................................... SUPPLEMENTARY DATA ...............................................................................

ACKNOWLEDGMENTS

We are thankful to Philippe Masson, LADAF's embalmer, for the cadaver's preparation and for his availability, amiability and professionalism. We are also thankful to all rescuers who gave their time to participate to this study.

ABSTRACT

Background: Pulmonary aspirations of gastric content are frequent during cardiac arrest resuscitation. Endotracheal intubation is the gold standard to protect airways but supraglotticairway-devices (SGA) may provide similar protection with less learning. Bag-mask ventilation (BMV) is the most common method used by rescuers. We hypothesized that early use of SGA by rescuers could reduce pulmonary aspiration in a human cadaver CPR model.

Methods:

Protocol A: after a 3-hours training period, each rescuer were randomly assigned to use SGA (i-gel ® ) or BMV during a 5 min standard CPR period. Foley catheter was introduced in the cadaver's stomach and filled up with 300 mL of a randomized blue or green serum saline solution. On a crossover design, the stomach was then emptied and filled with the second 300 mL colored serum saline solution with another 5 min CPR period using the other airway method. Pulmonary aspiration was defined as the presence of colored serum saline solution below the vocal cords as assessed by fiber-optic bronchoscopy by a blinded operator. Protocol B : for each 5 min CPR period we assessed insufflation success rate, intra-gastric pressure trough the foley catheter and CPR time points and intervals (time to start CPR, first defibrillation, no-flow duration). A generalized linear mixed model was performed for statistical analysis. Data are presented as n (%) and median (IQR 25-75).

Results:

In protocol A, ten cadavers were included to perform twenty CPR periods. Aspiration occurred in 2 (20%) in the SGA group and 5 (50%) in the BMV group; p = 0.44. In protocol B, forty-eight rescuers performed forty-eight CPR periods on eleven cadavers. Insufflation success rate was higher with SGA than BMV: 75.0% (25.0; 50.0) vs. 34

Protocol A

None outcome was missing among the 20 CPR performed by 20 rescuers on 10 cadavers. We observed a non-significant reduction of pulmonary aspirations in SGA group.

Aspiration occurred in 2 (20%) in SGA group and 5 (50%) in BMV group, p = 0.44 (Fig. 3). A non-significantly lower rate of aspiration was observed with SGA .

Fig. 3 -Protocol A : aspirations of gastric content

Early airway management could be essential in the early phase of CPR to reduce pulmonary aspiration of gastric content. Clinical consequences are high but variable and may include chemical pneumonitis, as well as infectious pneumonia, exacerbation of a pre-existing asthmatic disease, acute lung injury or even acute respiratory distress syndrome [START_REF] Beck-Schimmer | Bronchoaspiration: incidence, consequences and management[END_REF] . Pneumonias may occur up to 60% in ICU post-cardiac arrest patients [START_REF] Pabst | Predictors and outcome of early-onset pneumonia after out-of-hospital cardiac arrest[END_REF] . Moreover, gastric regurgitations could be a predictive factor of poor neurological outcome after cardiac arrest [START_REF] Früh | Gastric regurgitation predicts neurological outcome in out-of-hospital cardiac arrest survivors[END_REF] . We found that SGA's use was associated with a non-significant reduction of aspirations. These results are encouraging and in adequation with precedent studies [START_REF] Stone | The incidence of regurgitation during cardiopulmonary resuscitation: a comparison between the bag valve mask and laryngeal mask airway[END_REF] but more studies are necessary to confirm these results. This is the first study that compares SGA and BMV ventilation efficiency and efficacy in basic life supportless rescuers population. Previous studies in novice population showed a more difficult ventilation with BMV than SGA [START_REF] Hart | Efficacy of Laryngeal Tube versus Bag Mask Ventilation by Inexperienced Providers[END_REF][START_REF] Timmermann | Novices Ventilate and Intubate Quicker and Safer via Intubating Laryngeal Mask Than by Conventional Bag-Mask Ventilation and Laryngoscopy[END_REF] . BMV requires regular training to perform adequate ventilation. With only a 3 hours training, rescuers improved insufflation success rate with SGA. SGA seem easy and safe in this population [START_REF] Bielski | Comparison of blind intubation with different supraglottic airway devices by inexperienced physicians in several airway scenarios: a manikin study[END_REF][START_REF] Wharton | I-gel insertion by novices in manikins and patients*[END_REF][START_REF] Henlin | Comparison of Five 2nd-Generation Supraglottic Airway Devices for Airway Management Performed by Novice Military Operators[END_REF][START_REF] Ohchi | Evaluation of the efficacy of six supraglottic devices for airway management in dark conditions: a crossover randomized simulation trial[END_REF] . Although easy to use 27 , i-gel ® showed a good performance on pulmonary aspirations compared to other SGA, BMV and endotracheal intubation in a previous cadaver study [START_REF] Piegeler | Evaluation of six different airway devices regarding regurgitation and pulmonary aspiration during cardio-pulmonary resuscitation (CPR) -A human cadaver pilot study[END_REF] , that's why we chose to use it.

Intragastric pressures were measured to compare gastric inflation pressure between SGA and BMV. Limiting gastric insufflation during cardiac arrest is the way to reduce pulmonary aspirations. With BMV and with the head in the normal position, insufflated pressures < 15 cm H2O rarely produced insufflation of the stomach, while pressures ≥ 25 cm H2O did in most subjects [START_REF] Ruben | Gastric Inflation in Relation to Airway Pressure[END_REF] . Some studies suggest that optimal inspiratory time is around 1

CONFLICT OF INTEREST

Intersurgical ® gave us i-gel ® and bag-valve mask samples to realize this study. They also lend us a fiberoptic bronchoscopy monitor (Ambu® aView™ monitor) to assess pulmonary aspirations. Intersurgical ® had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

LADAF, which is an academic Laboratory (Grenoble Alps University), funded this research.

The authors declares no other conflict of interest.

SUPPLEMENTARY DATA

We can see difference between gastric insufflation and no gastric insufflation

Annex -Cadaver's characteristics and number of participation in each protocol


Clémence Léobal
email: clemence.leobal@cnrs.fr

This paper is a reflection on my research experience in urban sociology in French Guiana, carried out within Parisian universities. Within social sciences, this French département in South America escapes both Latin American studies, which are largely Spanish-speaking, and Caribbean studies, which are not well developed in France. Research on French Guiana as on other parts of the former colonial empire, that remain under French control, officially called "Overseas territories" (Outre-mer), is carried out in local university departments or in research centers in Europe or North America (or even Brazil). It is difficult to establish a dialogue between these works, notably because of the variety of regions in which these territories are located (continental America, the Caribbean, the Indian Ocean, Oceania). Academics from other disciplines (in ecology, for example) who work on French Guiana refer more readily to Amazonia to the point of frequently making the keyword French Guiana disappear from publications. However, it seems unthinkable in social sciences to make the land and its specificities as a French territory disappear. This is why I have chosen to insert my work in academic networks on "Overseas territories." In France, this field is not very well structured and is deprived of a journal or a research unit, but operates through thematic research projects and seminars.

(version originale en français plus bas dans le document)

*** I come from the Paris region. I did my thesis in urban sociology on a town in French Guiana, while enrolled in a Parisian university. Guiana is a territory that is relatively little studied in French sociology or political science courses. In terms of cultural areas, this French department in South America escapes the cultural areas in the social sciences: it is not often included in the fields of Latin American studies, which are largely Spanish-or Portuguese-speaking, even though the Guiana Shield is an integral part of Amazonia; and it is often attached to Caribbean studies, from which it is nonetheless distinct due to its continental location. Several academic networks on Guyana co-exist informally, by discipline. Academics in the natural sciences from all over the world refer more readily to the 'Amazon' region, to the extent that the keyword French Guiana frequently disappears from the referencing of English-language publications (Noucher, 2020). In the social sciences, it is not common to ignore the specificities of this territory as a former French colony and department. The creation of a University of French Guiana, autonomous from the University of the Antilles, in 2014, has created new dynamics in the social sciences, by organising international colloquiums on site. However, it does not (yet) constitute a reference centre in comparison with the major universities in France, Europe or the Americas that fund research and fieldwork in French Guiana. After having analysed my own research career, I would like to ask myself about the ways of networking beyond cultural areas around decolonial issues.

Who to do research with on French Guiana?

The anthropologist Catherine Benoît analysed the difficulties she experienced during her doctoral and post-doctoral studies in France in establishing the legitimacy of her work on Guadeloupe, another French « oversea departement » located in the Carribean. She finally pursued her research from the United States (2009). For my part, after a two-year voluntary service at the Saint-Laurentdu-Maroni town hall, I resumed my studies in the social sciences by enrolling in a master's degree at the École des Hautes Études en Sciences Sociales and then in a doctorate at the Université Paris Descartes, where I obtained funding for a doctoral contract in 2012. My research proposal was in the field of urban studies, and I was interested in the implementation of French urban policies (overall the so-called 'resorption of substandard housing') in French Guiana. I therefore did not seek to be part of research networks in terms of cultural areas but rather in thematic networks linked to urban issues, which motivated my choice to turn to particular academics as my supervisors: the woman who became my dissertation supevisor was a historian specialising in the city of Paris, and my thesis supervisor was a sociologist who had worked on various aspects of housing and hospitality in the city. I also had a co-director who specialised in the history of anthropology and the anthropology of the State in Brazil. So, through my supervisors, I was rather inserted in thematic networks on public policies, as well as Brazilian studies.

In the course of my research work, I engaged in a critical dialogue with existing social science work on French Guiana. The research on this territory was due less to sociologists or politicians than to anthropologists, historians, geographers and linguists. There work was often delimited by ethnicised boundaries, particularly for ethnological or ethnolinguistic studies, in accordance with a disciplinary tradition centred on a community considered as an isolate [START_REF] Fabian | Le temps et les autres: comment l'anthropologie construit son objet, traduit par Bernard Müller et traduit par Estelle Henry-Bossonney[END_REF]. Furthermore, French Amazon anthropology has a strong prism for indigenous peoples, structured in the 1960's by Claude Levi-Strauss. Studies on Afro-descendant populations living in the Amazon are more marginal in this disciplinary field, as illustrated by the fact that the work of Roger Bastide has had a lesser posterity than that of Levi-Strauss. As my study focused in part on the Bushinengue popular classes, staming from the marronage of the Surinamese plantations, I was included in scientific events bringing together Bushinengue specialists. In particular, I took part in the colloquium on the history of marronage organised in 2013 by the historian Jean Moomou in Saint-Laurent-du-Maroni (Moomou, 2015); or in the colloquium on the anthropology of the Bushinengue organised by the anthropologist Olívia Da Cunha in 2014 in Rio de Janeiro [START_REF] Cunha Olívia | Maroon Cosmopolitics: Personhood, Creativity and Incorporation[END_REF]. But among these academics, the 'classical' approach predominated and my work on contemporary urban policies found little resonance; one prominent US Maroon scholar even confessed to me after my defense: "Housing, we're not interested." Even though I drew a lot of inspiration from it, and individual collaborations were able to emerge within it, notably with Bettina Migge or Olivia Da Cunha, I did not feel that I really belonged to this small scientific community.

In order to establish academic links on a regional scale, I sought instead to integrate myself into work on Latin America. Indeed, Guyana is located on this continent and human and cultural exchanges are very intense on its borders. To give an example, the case of gold panning, considered illegal in French Guyana, cannot be analysed outside of the circulation of workers and commercial networks on the scale of the entire Amazon, as Dutch researchers working in Suriname have shown [START_REF] Heemskerk Marieke | Moving frontiers in the Amazon. Brazilian small-scale gold miners in Suriname[END_REF]. However, the integration of the Guiana Shield into Latin American studies is not self-evident, firstly for linguistic reasons: the official language of the former colonisers differs, since that of Guyana is French, that of Guyana is English and that of Suriname is Dutch. On the other hand, academic work on Latin America is mainly in Spanish. I realised the extent of the problem when I participated in the Journée des Jeunes Américanistes organised by a French research centre in Guatemala in 2013, where I was able to speak in English but most of the exchanges were in Spanish, a language I did not know. The following year, I did an academic exchange in Brazil, at the National Museum of Rio de Janeiro via an exchange programme led by my co-supervisor. I was able to learn the basics of Portuguese and participate in this rich Franco-Brazilian exchange programme throughout my thesis. However, within Latin American studies networks, the question of the relevance of my inclusion remained open for many academics, as illustrated by the heated debates they told me to have had about my proposal in a 2019 Paris colloquium, entitled 'Inhabiting Latin American Cities, about whether or not to include French Guiana in the area under study -my proposal was eventually accepted (Fuster-Farfán et al, 2021).

The scale of the Guiana Shield also gives rise to attempts at apprehension by the social sciences. For geographers, this space between the Orinoco and Amazon rivers refers to French Guiana, Suriname and Guyana, but also parts of Venezuela, Colombia and the Brazilian state of Amapá. I had the opportunity to participate in two academic initiatives that referred to the three Guianas, but did not really succeed in crossing national academic boundaries. An international project launched by a French academic in English-speaking literary studies, Judith Misrahi-Barak, aimed to set up a network on the three Guyanas. Three successive colloquia were held in 2015 and 2016 in London, Amsterdam and Montpellier, which aimed to bring together different humanities and sciences. One of the things I discovered was that Guyana is a country that has produced a number of prolific writers such as Wilson Harris and Edgar Mittelholzer, who are very rarely translated into French. However, the final publication in English (Aje et al., 2019) does not reflect the diversity of the participants, with a strong focus on literary studies in Guyana, and few texts on other territories. Language barriers arose in particular in the absence of a budget for translations: my own contribution had to be abandoned for lack of professional translation. In 2020, a journal issue on 'Social relations, ethno-racial relations in the three Guianas', coordinated by the French political scientists Stéphanie Guyon and Marie-Hélène Sa Vilas Boas, was published in the Cahier des Amériques Latines, which evokes fields located in the three Guianas but whose authors are all French-speaking.

During the course of my doctoral studies in France, with the international openings that I have mentioned, I did not have the opportunity to become involved in research networks on the Caribbean. I considered -and still think -that their insular geographical situation places them in a completely different relationship with the Americas than Guyana.

During the course of my doctoral studies in France, with the international openings that I have mentioned, I did not have the opportunity to become involved in research networks on the Caribbean. I considered -and continue to think -that their insular geographical situation places the French West Indies (Guadeloupe and Martinique) in a completely different relationship with the Americas than Guyana. However, these so-called "overseas" departments share a common status that should be taken into account in the analysis and in the constitution of research networks.

Analysing the reconfigurations of contemporary (post)colonial power

In 1946, what remained of France's 'old colonies' (Guadeloupe, Martinique, French Guiana and Reunion) were given the status of French 'overseas departments', a vague and metonymic category that groups together countries and peoples located in the Americas and the Indian Ocean. In addition to the four departments, Mayotte was considered by France to be separate from the rest of the Comoros archipelago when the latter voted for independence in 1975 (a border creation that has been condemned fourteen times by the UN since then); Mayotte was finally transformed into a « overseas departement » in 2011. In addition to the five departments, seven overseas collectivities of varying status are still attached to France: Saint-Pierre-et-Miquelon, Saint-Barthélemy and Saint-Martin in the Atlantic, Wallis and Futuna, French Polynesia and New Caledonia in Oceania, and the 'French state-owned properties' of the Southern and Antarctic Lands. In French Guiana, as elsewhere, research on these 'overseas territories' is carried out in local university centres or in research centres in Europe or North America (or even Brazil recently). It is difficult to establish a dialogue between these works, especially because of the variety of regions in which these territories are located (Americas, Caribbean, Indian Ocean, Oceania).

Since I finished my thesis in 2017, I no longer conduct research in French Guiana where I no longer live. But I continue to carry out research and animation activities at the level of the different "overseas territories", from mainland France. « Overseas » is not a cultural area, in the sense that the spaces concerned are located on almost every continent, and that no one defines oneselves by saying "I am an overseaser". This scale of analysis is nevertheless fruitful for two reasons: firstly, it allows us to understand the social spaces in which this categorisation of overseaser (ultramarin) has meaning, particularly in the upper echelons of the French administration. Furthermore, this scale invites the analysis of contemporary (post)colonial relations of power.

Despite the respective geographical remoteness of these areas, and their immense linguistic and cultural diversity, they are attached to French administrations that functions through the circulation of civil servants, some of whom are specialised in the 'overseas'. If we can speak of an 'overseas culture', it is indeed that of French civil servants, most of whom are White metropolitans, who hold positions in these territories and are directly linked to a Ministry for Overseas France -currently a Secretariat of State -located on rue Oudinot in Paris. This is why I was led to work on this notion during my thesis on urban policies: to my great surprise, the urban planners I was questioning about the role they had played in French Guyana spoke to me at length about their past experiences in Guadeloupe or Mayotte... I thus understood that they were part of a network of civil servants originating from the 'metropolis' who had devised special housing policies for the 'Overseas' that were applied in the city I studied in French Guiana, among others. The 'post-imperial' circulations of these professionals also fed into my analyses, which thus articulated the local scale with that of the 'overseas'. Nowadays, I am participating in a collective research launched by Stéphanie Guyon on the careers of senior French civil servants (hauts-fonctionnaires) in the 'overseas' (mainly magistrates and prefects). These so-called 'overseas' experiences are narrated by the people concerned and are articulated within career strategies that are the condition for the existence of this 'overseas culture'. This scale of analysis allows for cross-checks and comparisons that open up enriching perspectives on the contemporary configurations of situations alternately described, depending on the authors, as colonial, post-colonial or neo-colonial, in a critical perspective sometimes referred to as 'decolonial'. For example, some authors have proposed the concept of 'welfare colonialism' to describe the situation of the DOM [START_REF] Héloïse | Governing Rights in La Réunion: Social Legislation, Landholding, Housing and the Making of France in the Indian Ocean, 1946-2009[END_REF][START_REF] Paris | Nous qui versons la vie goutte à goutte -Féminismes et économie reproductive : une sociohistoire du pouvoir colonial à la Réunion[END_REF]. I am a member of an association founded by the philosopher Malcolm Ferdinand, the Earth-World Observatory, which aims to promote research on ecological issues in the 'overseas' and nearby regions. The aim is to feed reflections on ecology from situations experienced in these peripheral spaces in a perspective of decolonial ecology [START_REF] Ferdinand | Une écologie décoloniale: penser l'écologie depuis le monde caribéen[END_REF]. This implies not limiting oneself to the French borders but articulating comparisons with the Comoros, the Caribbean, the three Guyanas and Brazil, etc.

Research on "Overseas" is not very structured: it operates in France without a journal or research laboratory. Nevertheless these networks are activated through thematic research projects, research networks and seminars, such as the two projects I mentioned, and others1 . These networks make full use of distance communication and in particular video-conferencing to bring together scholars from all continents. The problem of time zones is rather difficult for these links, since the spaces and people are located in zones that are difficult to combine by more than two. But it seems to me that the heuristic contribution of these connections lies in the global critical perspective that they may allow, beyond cultural areas.

Faire des sciences sociales en Guyane, un lieu hors-cadre des aires culturelles.

(Session 1 : Découper, nommer, instituer) Originaire de la région parisienne, j'ai fait ma thèse de sociologie urbaine sur une ville de Guyane, en étant inscrite dans une université parisienne. La Guyane est un territoire relativement peu étudié dans les cursus de l'Hexagone en sociologie ou sciences politiques. En termes d'aires culturelles, ce département français d'Amérique du Sud échappe aux aires culturelles en sciences sociales : il n'est pas souvent inclus dans les terrains des études latino-américaines largement hispanophones ou lusophones, alors même que le Plateau des Guyanes fait partie intégrante de l'Amazonie ; et il est souvent rattaché aux études caribéennes dont il se distingue pourtant du fait de sa localisation continentale. Plusieurs réseaux universitaires sur la Guyane coexistent de manière informelle, par disciplines. Des universitaires de sciences naturelles du monde entier se réfèrent plus volontiers à la région 'Amazonie' au point de fréquemment faire disparaître le mot-clé French Guiana du référencement des publications anglophones [START_REF] Noucher | Quand le terrain disparaît des articles scientifiques[END_REF]. En sciences sociales, il n'est pas courant de faire abstraction des spécificités de ce territoire en tant qu'ancienne colonie et département français. La création d'une université de Guyane autonome de celle des Antilles, en 2014, insuffle de nouvelles dynamiques en sciences sociales, en organisation des colloques internationaux sur place. Mais elle ne constitue pas (encore) un pôle de référence face aux grandes universités de France hexagone, d'Europe ou d'Amérique qui financent des recherches et des terrains en Guyane. Après avoir analysé mon parcours de recherche, je m'interrogerais sur les manières de faire réseau au-delà des aires culturelles autour des questions décoloniales.

Avec qui faire de la recherche sur la Guyane ?

L'anthropologue Catherine Benoît a analysé les difficultés qu'elle a connu, dans son parcours doctoral et postdoctoral en France, à asseoir la légitimité d'un travail sur la Guadeloupe, qui l'ont conduite à poursuivre ses recherches depuis les États-Unis (2009). Pour ma part, après avoir effectué un volontariat de deux ans à la mairie de Saint-Laurent-du-Maroni, j'ai repris des études en sciences sociales en m'inscrivant dans un master de l'École des Hautes Études sur la Guyane, puis en doctorat à l'université Paris Descartes où j'ai obtenu en 2012 un financement par contrat doctoral. Ma proposition de recherche s'inscrivait dans le champs des études urbaines, je m'intéressais en particulier au déploiement de certaines politiques urbaines françaises (notamment la dite 'résorption de l'habitat insalubre'). Je n'ai donc pas cherché à m'inscrire dans des réseaux de recherche en termes d'aires culturelles mais plutôt dans des réseaux thématiques liés aux questions urbaines, qui a motivé les choix de me tourner vers des universitaires donnés : celle qui est devenue ma directrice de mémoire est une historienne spécialiste de la ville de Paris, et ma directrice de thèse, une sociologue qui avait travaillé sur différents aspects de l'habitat, et de l'hospitalité en ville. J'avais également un codirecteur spécialisé en histoire de l'anthropologie et en anthropologie de l'État au Brésil. Je me suis donc, via mes directeurs et directrices de recherche, plutôt insérée dans des réseaux thématiques sur des politiques publiques, ainsi que via mon directeur de recherche sur le Brésil.

Au cours de mon travail de recherche, j'ai engagé un dialogue critique avec les travaux existant en sciences sociales sur la Guyane. Ces travaux étaient moins dû à des sociologues ou des politiques, qu'à des anthropologues, historiens, géographes et linguistes. Ces travaux étaient souvent délimités par des frontières ethnicisées, notamment pour les études ethnologiques ou ethnolinguistiques, conformément à une tradition disciplinaire centrée sur une communauté envisagée comme un isolat [START_REF] Fabian | Le temps et les autres: comment l'anthropologie construit son objet, traduit par Bernard Müller et traduit par Estelle Henry-Bossonney[END_REF]. Par ailleurs, l'anthropologie amazoniste française a un prisme fort pour les peuples autochtones, structurée dans les années 1960 par Claude Levi-Strauss. Les études sur les populations afro-descendantes vivant en Amazonie sont plus marginales dans ce champ disciplinaire, comme l'illustre le fait que l'oeuvre de Roger Bastide a connu une postérité moins large que celle de Lévi-Strauss. Comme mon étude portait en partie sur les classes populaires bushinenguées, issues du marronnage des plantations surinamaises, j'ai été intégrée à des évènements scientifiques réunissant les spécialistes des Bushinengué.e.s. Notamment, j'ai participé au colloque sur l'histoire des marronnages organisé en 2013 par l'historien Jean Moomou à Saint-Laurent-du-Maroni (Moomou, 2015); ou encore au colloque d'anthropologie des Bushinengué.e.s organisé par l'anthropologue Olívia Da Cunha en 2014 à Rio de Janeiro [START_REF] Cunha Olívia | Maroon Cosmopolitics: Personhood, Creativity and Incorporation[END_REF]. Mais parmi ces universitaires, l'approche « classique » prédominait et mon travail sur les politiques urbaines contemporaines trouvait peu d'écho ; un éminent spécialiste états-unien des Marrons m'a même avoué, après ma soutenance : « Le logement, ça ne nous intéresse pas. » Même si je m'en suis énormément nourrie, et que des collaborations individuelles ont pu émerger en son sein, notamment avec Bettina Migge ou Olivia Da Cunha, je ne me sentais pas tout à fait appartenir à cette petite communauté scientifique.

Pour établir des liens académiques à l'échelle régionale, j'ai plutôt cherché à m'intégrer à des travaux sur l'Amérique latine. En effet la Guyane est localisée sur ce continent et les échanges humains et culturels sont très intenses à ses frontières. Pour donner un exemple, le cas de l'orpaillage qualifié d'illégal en Guyane ne peut pas être analysé en dehors des circulations de travailleurs et des réseaux commerciaux à l'échelle de l'Amazonie entière, comme l'ont montré des chercheuses néerlandaises travaillant au Suriname [START_REF] Heemskerk Marieke | Moving frontiers in the Amazon. Brazilian small-scale gold miners in Suriname[END_REF]. Toutefois l'intégration des terrains du Plateau des Guyanes au sein des études latino-américaines ne va pas de soi, à commencer pour des raisons linguistiques : la langue officielle des anciens colonisateurs diffère, puisque celle de la Guyane est le français, celle du Guyana l'anglais et celle du Suriname le néérlandais. A contrario les travaux académiques sont majoritairement hispanophones. J'ai réalisé l'ampleur du problème en participant à la Journée des Jeunes Américanistes organisée par un centre de recherche français au Guatemala en 2013, auquel j'ai pu prendre la parole en anglais mais dont l'essentiel des échanges se déroulaient en espagnol, langue que je connaissais pas. L'année suivante, j'ai fait un échange universitaire au Brésil, au Musée national de Rio de Janeiro via un programme d'échange animé par mon codirecteur. J'ai pu ainsi apprendre les bases du portugais et participer à ce riche programme d'échange franco-brésilien tout au long de ma thèse. Toutefois, dans les réseaux des études latino-américaines, la question de la pertinence de mon intégration restait ouverte pour beaucoup d'universitaires, comme l'illustrent les débats vifs que l'on m'a rapportés au sujet de ma proposition dans un colloque à Paris en 2019, intitulé « Habiter les villes latinoaméricaines, au sujet de l'inclusion ou non de la Guyane dans l'aire étudiée -ma proposition a finalement été acceptée (Fuster-Farfán et al, 2021). L'échelle du plateau des Guyanes suscite également des tentatives d'appréhension par les sciences sociales. Cet espace compris entre les fleuves Orénoque et Amazone renvoie pour les géographes à la Guyane, au Suriname et au Guyana, mais aussi des parties du Venezuala, de Colombie et de l'État brésilien de l'Amapá. J'ai eu l'occasion de participer à deux initiatives académiques qui se référaient aux trois Guyanes, sans toutefois réussir véritablement à franchir les frontières nationales académiques. Un projet international lancé par une universitaire française en études littéraires anglophones, Judith Misrahi-Barak, visait à monter un réseau sur les trois Guyanes. Trois colloques successifs ont eu lieu en 2015 et 2016 à Londres, Amsterdam et Montpellier qui visaient à réunir différentes sciences humaines et lettres. J'y ai notamment découvert que le Guyana est un pays qui a vu naître nombre d'écrivains prolifiques comme Wilson Harris et Edgar Mittelholzer, qui sont très peu traduits en français. Toutefois, la publication finale en anglais (Aje et al., 2019) ne reflète pas la diversité des participants, et comporte un fort prisme sur les études littéraires au Guyana, et peu de textes portant sur les autres territoires. Des barrières linguistiques se sont notamment posées en l'absence de budget prévu pour les traductions : ma propre contribution a dû être abandonnée faute de traduction professionnelle. En 2020, un numéro de revue sur 'Relations sociales, relations ethnoraciales dans les trois Guyanes', coordonné par les politistes françaises Stéphanie Guyon et Marie-Hélène Sa Vilas Boas, est paru dans le Cahier des Amériques Latines, qui évoquent des terrains situés dans les trois Guyanes mais dont tous les auteurs sont francophones.

Au fil de ce parcours doctoral réalisé en France, avec les ouvertures internationales que j'ai mentionnées, je n'ai pas eu l'occasion de m'insérer dans les réseaux de recherche sur la Caraïbe. Je considérais -et continue de penser -que leur situation géographique insulaire place les Antilles françaises (Guadeloupe et Martinique) dans un tout autre rapport avec les Amériques que la Guyane. Ces départements dits « d'outre-mer » partagent toutefois un statut commun qu'il convient de prendre en compte dans l'analyse et dans la constitution de réseaux de recherches.

Analyser les reconfigurations du pouvoir (post)colonial contemporain

En 1946, ce qui restait à la France des « vieilles colonies » (Guadeloupe, Martinique, Guyane et Réunion) ont obtenu le statut de départements français dits « d'Outre-mer », catégorie floue et métonymique qui permet de regrouper des pays et des peuples situés dans les Amériques et dans l'Océan Indien. Aux quatre départements s'ajoute Mayotte qui a été considérée par la France comme distincte du reste de l'archipel des Comores, lors que celles-ci ont voté pour leur indépendance en 1975 (création de frontière qui a été condamnée à quatorze reprises par l'ONU depuis) ; Mayotte a finalement été départementalisée en 2011. Outre les cinq départements, sept collectivités d'Outre-mer aux statuts divers sont à ce jour encore rattachées à la France : Saint-Pierre-et-Miquelon, Saint-Barthélemy et Saint-Martin dans l'Atlantique, Wallis-et-Futuna, la Polynésie française et la Nouvelle Calédonie, en Océanie, et les « propriétés domaniales de l'État français » des terres australes et antarctiques. En Guyane comme ailleurs, les recherches sur ces « Outre-mer », sont réalisées dans les centres universitaires locaux ou dans des centres de recherche d'Europe ou d'Amérique du Nord (voire du Brésil depuis peu). Ces travaux sont difficiles à faire dialoguer entre eux notamment du fait de la variété des régions dans lesquelles ces territoires s'inscrivent (Amériques, Caraïbes, Océan Indien, Océanie). Depuis que j'ai terminé ma thèse en 2017, je ne mène plus de recherche en Guyane où je n'habite plus. Mais je continue de mener des activités de recherche et d'animation à l'échelle des différents « Outre-mer », depuis l'Hexagone. Il ne s'agit d'une aire culturelle, au sens où les espaces concernés sont situés sur presque tous les continents, et que sur place, personne ne se définit en disant « je suis ultramarin ». Cette échelle d'analyse est néanmoins fructueuse pour deux raisons : tout d'abord, elle permet de comprendre les espaces sociaux dans lesquels cette catégorisation d'ultra-marin a du sens, notamment dans les hautes sphères de l'administration. De plus, cette échelle inviter à analyser les rapports de domination (post)coloniaux contemporains. Malgré l'éloignement géographique respectif de ces espaces, et leur immense diversité linguistique et culturelle, ils sont rattachés à des administrations françaises qui coopèrent notamment par le biais de la circulation des fonctionnaires, dont certains sont spécialisés dans les « Outre-mer ». Si l'on peut parler d'une « culture ultramarine », il s'agit bien de celle des fonctionnaires français, pour la plupart métropolitains, qui occupent des postes dans ces territoires et sont directement en lien avec un Ministère des Outre-Mer, actuellement Secrétariat d'État, situé rue Oudinot à paris. C'est la raison pour laquelle j'ai été amenée à travailler sur cette notion au cours de mon travail de thèse sur les politiques urbaines : à ma grande surprise, des urbanistes que j'interrogeais sur le rôle qu'il avaient pu jouer en Guyane me parlaient longuement de leurs expériences passées en Guadeloupe ou à Mayotte… J'ai ainsi compris qu'ils faisaient partie d'un réseau de fonctionnaires originaires de « métropole » qui avaient conçues des politiques d'habitat spéciales pour les « Outre-mer » qui s'appliquaient entre autres sur mon terrain. Les circulations « post-impériales » de ces professionnels ont également nourri mes analyses qui articulaient ainsi l'échelle locale avec celle des « Outre-mer ». Je participe actuellement à une enquête collective lancée par Stéphanie Guyon sur les carrières des hauts-fonctionnaires français dans les « Outre-mer » (magistrats et préfets principalement). Ces expériences dites « ultramarines » sont mises en récits par les personnes concernées et s'articulent au sein de stratégies de carrières qui sont la condition de l'existence de cette « culture d'Outre-mer ».

Cette échelle d'analyse permet des recoupements et des comparaisons qui ouvrent des perspectives enrichissantes sur les configurations contemporaines de situations alternativement qualifiées, selon les auteurs, de coloniales, postcoloniales ou du néocoloniales, dans une perspective critique parfois appelée « décoloniale ». C'est ainsi que des autrices proposent le concept de « welfare colonialism » pour décrire la situation des DOM [START_REF] Héloïse | Governing Rights in La Réunion: Social Legislation, Landholding, Housing and the Making of France in the Indian Ocean, 1946-2009[END_REF][START_REF] Paris | Nous qui versons la vie goutte à goutte -Féminismes et économie reproductive : une sociohistoire du pouvoir colonial à la Réunion[END_REF]. Je suis membre d'une association fondée par le philosophe Malcom Ferdinand, l'Observatoire Terre-Monde, qui vise à valoriser les recherches sur les questions écologiques dans les « Outre-mer » et proches régions. L'objectif est d'alimenter les réflexions sur l'écologie à partir de situations vécues dans ces espaces périphériques dans une perspective d'écologie décoloniale [START_REF] Ferdinand | Une écologie décoloniale: penser l'écologie depuis le monde caribéen[END_REF]. Cela implique de ne pas se limiter aux frontières françaises mais à articuler des comparaisons avec les Comores, les Caraïbes, les trois Guyanes et le Brésil, etc... Les recherches sur « l'Outre-mer » sont peu structurées : elles fonctionnent en France sans revue, ni laboratoire de recherche : mais ces réseaux s'activent au gré de projets de recherche thématiques, de réseaux de recherche et de séminaires, comme les deux projets que j'ai mentionnés, et d'autres encore 2 . Ces réseaux utilisent pleinement les moyens de communication à distance et notamment la visioconférence pour faire des dialoguer des universitaires présents sur tous les continents. Le problème des fuseaux horaires est assez corsé pour ces mises en lien, puis que les espaces et les personnes sont situées dans des fuseaux difficilement combinables par plus de deux. Mais il me semble que l'apport heuristique de ces rapprochements se situe au niveau de la perspective critique globale qu'ils peuvent peut-être permettre, au-delà des aires culturelles.

2 Par exemple, le projet de recherche sur l'émigration organisée par l'État français dans le cadre du BUMIDOM, coordonné par Audrey Célestine ; ou encore le séminaire "Outre-mer et recherche en sciences sociales : jeux d'échelles et de souverainetés" coordonné par Valelia Muni Toke.

For example, the research project on emigration organised by the French State in the framework of the BUMIDOM, coordinated by Audrey Célestine; or the seminar "Overseas and social science research: games of scale and sovereignty" coordinated by Valelia Muni Toke.