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Au Dr David Brossier, merci infiniment de m'avoir épaulé pour ce travail de thèse. Merci pour ta disponibilité, ton soutien, tes réponses à mes questions et toute l'aide que tu m'as apporté.

Au Professeur Claire Dupont, merci d'avoir accepté de présider mon jury. Merci également pour ta disponibilité et ton accompagnement dans ma formation. J'espère que notre travail te plaira.

Au Dr Dollet, merci d'apporter ton expertise à notre travail en acceptant de participer à mon jury de thèse.

Aux médecins du service de réanimation pédiatrique, en particulier les Dr Chomton-Cailliez, Dr Jokic, Dr Letouze et Dr Villedieu, merci de m'avoir encadré lors de mon parcours en réanimation. J'ai beaucoup appris à vos côtés, grâce à votre écoute et votre confiance ! Aux équipes de pédiatrie et urgences pédiatriques du CHU de Caen et à l'ensemble des médecins notamment à Lille, Avranches et Saint-Lô qui ont participé à mon apprentissage.

A mon papa, merci pour tout. Tu es un exemple, un repère et surtout mon protecteur. C'est grâce à ton amour et ton soutien sans faille que je suis aujourd'hui moi aussi un père heureux. Je te dois beaucoup, j'espère te rendre fier.

A ma maman, merci pour tout, Je n'arriverai jamais à combler le vide laissé par ton absence mais tu es aujourd'hui notre bonne étoile et nous le démontre chaque jour.

A Claire, merci de m'avoir appris que l'amour est la plus grande force. Merci d'être toujours à mes côtés, de prendre soin de moi et de rendre les mauvais jours moins mauvais. Merci de m'avoir donné les plus beaux souvenirs de ma vie, je suis un papa comblé et toi une mère incroyable.

A Siméon, merci d'être entré dans nos vie et de m'avoir appris ce que signifiait vraiment le mot « famille ». Tu représentes tout ce dont j'ai besoin : joie, amour, câlin, réconfort et sourire.

A ma soeur, Claire, merci d'être là dans les bons et les mauvais moments, de m'épauler. J'ai une chance incroyable d'avoir pu grandir à tes côtés. Tu seras toujours ma petite soeur préférée.

A l'ensemble de ma famille, mon parrain, ma marraine, merci pour votre soutien.

A mes amis, en particulier Élise, François, Manon, Maxime, Nolwen, et tout le « bungalow » qui se reconnaitra, vous comptez aussi beaucoup pour moi. Merci à vous pour ces belles années. Vous avez rendu ce long parcours mémorable. -Au coefficient d'absorption molaire (𝜀), qui est une propriété physique unique de la solution pour une longueur d'onde spécifique.

Abréviations

Figures et Tableaux

-À la longueur du trajet optique (d), qui est la distance que la lumière doit parcourir à travers la solution.

-À la concentration molaire de la solution (c). Un oxymètre de pouls transillumine les tissus avec deux longueurs d'ondes lumineuses (rouge, 660 nm ; et proche infrarouge, 940 nm) puis utilise un spectrophotomètre pour le calcul de la saturation en oxygène de l'hémoglobine selon l'absorbance de la lumière.

S'agissant de la même méthode de mesure que l'hémoglobinomètre de laboratoire, des efforts ont été faits pour modifier l'oxymètre de pouls afin qu'il mesure également la concentration d'hémoglobine. Plusieurs différences empêchant l'utilisation de la loi de Lambert-Beer ont compliqué le développement de cette technique de mesure :

-Le tissu à travers lequel la lumière est transmise n'est pas homogène à la différence de la suspension d'hémoglobine en laboratoire.

Introduction

Children hospitalized in the pediatric intensive care units (PICU) are at high risk of anemia. In the PICU, the vast majority of children (up to 74%) will have to face anemia at least one time during their stay (33% on admission, 41% during their stay) [START_REF] Bateman | Anemia, Blood Loss, and Blood Transfusions in North American Children in the Intensive Care Unit[END_REF]. The causes of anemia in these patients are numerous: excessive or repeated blood loss following abdominal trauma or post-operative complications, chronic diseases, deficiency disorders, liver dysfunction or disseminated intravascular coagulation...(1,2) Besides, pediatric patients are also at risk of iatrogenic anemia due to repeated blood sampling required for proper monitoring, resulting in significant blood loss [START_REF] Sztefko | Blood loss from laboratory diagnostic tests in children[END_REF]. As a consequence, many patients hospitalized in the PICU may require transfusions, which is associated with worse outcomes (more days on mechanical ventilation, increased mortality, more nosocomial infections and cardiorespiratory dysfunction) [START_REF] Bateman | Anemia, Blood Loss, and Blood Transfusions in North American Children in the Intensive Care Unit[END_REF][START_REF] Vincent | Anemia and Blood Transfusion in Critically Ill Patients[END_REF]. This makes rapid, reliable diagnosis of anemia all the more important.

However, this diagnosis relies on blood analysis, which presents obvious difficulties in children [START_REF] Stevens | Epidemiology and management of painful procedures in children in Canadian hospitals[END_REF]. The traditional method to obtain blood sample is invasive, requiring venipuncture with a needle, a painful procedure sometimes made difficult by poor venous capital or the child's lack of cooperation [START_REF] Slifer | Distraction, Exposure Therapy, Counterconditioning, and Topical Anesthetic for Acute Pain Management During Needle Sticks in Children With Intellectual and Developmental Disabilities[END_REF]. Such procedures can provoke severe distress and anxiety, especially when repeated. It can therefore be traumatic for patients and their parents, and a source of great discomfort for paramedical staff faced with the child's suffering [START_REF] Slifer | Distraction, Exposure Therapy, Counterconditioning, and Topical Anesthetic for Acute Pain Management During Needle Sticks in Children With Intellectual and Developmental Disabilities[END_REF][START_REF] Trottier | La gestion de la douleur et de l'anxiété chez les enfants lors de brèves interventions diagnostiques et thérapeutiques[END_REF].

In addition, technical and time constraints are associated with the conventional invasive method. Indeed, samples have to be transported to the laboratory and then technically processed, resulting in a delay of several minutes to several hours before results are available, not to mention unusable samples (insufficient quantity, coagulated or lost sample…). These constraints have led to the development of measuring devices used directly at the patient's bedside, such as the portable HemoCue system. It provides an estimation of hemoglobin (Hb) using a capillary blood sample taken from a fingertip. However, the reliability of these devices in intensive care units has been questioned in several studies, particularly in conditions where the capillary bed is impaired because of poor peripheral perfusion (hypovolemia, low cardiac output, vasopressor use…) [START_REF] Frasca | Reliability of the HemoCue® hemoglobinometer in critically ill patients[END_REF][START_REF] Seguin | Determination of capillary hemoglobin levels using the HemoCue system in intensive care patients[END_REF]. Additionally, they only allow intermittent monitoring, which can lead to avoidable errors or delays in diagnosis [START_REF] Frasca | Reliability of the HemoCue® hemoglobinometer in critically ill patients[END_REF].

For several years now, non-invasive Hb monitoring devices have been developed, such as the Masimo rainbow® pulse co-oximetry sensor (Masimo Corporation, Irvine, CA). It can determine Hb concentration using a finger sensor, based on different light absorption patterns at different wavelengths [START_REF] Shamir | The Current Status of Continuous Noninvasive Measurement of Total, Carboxy, and Methemoglobin Concentration[END_REF].

Several studies have evaluated the concordance between this non-invasive hemoglobin monitoring (SpHb) and the traditional invasive method with laboratory measurement (LabHb) in healthy pediatric patients [START_REF] Arai | Evaluation of the use of noninvasive hemoglobin measurement in early childhood[END_REF][START_REF] Wittenmeier | Comparison of the gold standard of hemoglobin measurement with the clinical standard (BGA) and noninvasive hemoglobin measurement (SpHb) in small children: a prospective diagnostic observational study. Bosenberg A, éditeur[END_REF] or per-operatively (13-15). However, only three studies evaluate its use and performance in PICU with results in favor of acceptable concordance [START_REF] Akyildiz | Noninvasive Measurement of Hemoglobin Using Spectrophotometry: Is it Useful for the Critically Ill Child?[END_REF][START_REF] García-Soler | Monitorización no invasiva transcutánea de la concentración de hemoglobina en pacientes críticos pediátricos con riesgo de sangrado[END_REF][START_REF] Phillips | A noninvasive hemoglobin monitor in the pediatric intensive care unit[END_REF]. Of these three studies, none assessed the continuous monitoring, and hence the variations and trends in SpHb values. Beyond simple value correlation, if trend accuracy could be demonstrated, the use of SpHb in PICU could enable close monitoring and help addressing the specific pediatric issues cited above.

The main objective of this study was to assess the reliability of SpHb trend compared with repeated invasive measurements considered as the goal standard. The secondary objective was to assess the reliability of SpHb absolute measurements at different time points.

Materials and methods

We conducted a single-center retrospective cohort observational study from June 1, 2021, to June 30, 2023 in a tertiary university hospital medical and surgical French PICU.

General management in the PICU

Data extraction

Data were collected from the EMR prospective database. We collected information on the following: 1) Patients' demographic characteristics: age, gender, admission date, discharge date, weight, height, body mass index (BMI); 2) Patients' medical data: reason for admission and pediatric index of mortality (PIM) score( 19), SpO2, temperature and HR;

3) Patients' management: ventilatory or aminergic support; 4) Specific data : length of sensor utilization, LabHb and concomitant SpHb.

Endpoints

The primary endpoint was trend of the SpHb, defined as the difference between two measures at two different time points of SpHb, and the corresponding LabHb trend.

The secondary endpoints were the absolute value of SpHb at admission, H6, H12, H24, H48 and H72 and the corresponding LabHb.

Statistical Analysis

The distribution of quantitative variables was analyzed with the Shapiro-Wilk test. The quantitative variables are presented as median [min-max] or mean (SD) as appropriate and qualitative variables as number (percentage). Qualitative variables were compared using a paired T-test or Wilcoxon signed rank tests depending on variable distribution. SpHb measurements were compared to LabHb values, considered as the gold standard.

We performed a descriptive analysis and examined the number of SpHb readings within 0-1, 1-2, 2-3 and > 3 g/dl of LabHb measurements. The correlation between SpHb and LabHb was determined by the Pearson correlation coefficient (r) and linear regression analysis with determination coefficient (R 2 ). The agreement between SpHb and LabHb was evaluated measuring the mean difference and using the Bland & Altman analysis. In the Bland-Altman analysis, we calculated the bias as the mean difference between the two measures and the limits of agreement as the interval within which 95% of the differences were expected to be [START_REF] Bland | Statistical methods for assessing agreement between two methods of clinical measurement[END_REF]. The tolerance limit was set at ± 1 g/dl, as it is the accuracy advertised by the manufacturer. The level of statistical significance was set at a p value < 0.05. All analyses were conducted in the complete-case analysis. Statistical analyses were performed using open-access R software, Version 4.2.1 (R Foundation for Statistical Computing, Vienna, Austria)

Results

Sixty-two patients met the inclusion criteria. Among them, ten were excluded due to missing data and 52 patients were finally included, which represented 109 pairs of SpHb and LabHb values (Figure 2). [1 -8] and the median length of stay was three days [START_REF] Bateman | Anemia, Blood Loss, and Blood Transfusions in North American Children in the Intensive Care Unit[END_REF][START_REF] Demaret | Anemia at pediatric intensive care unit discharge: prevalence and risk markers[END_REF][START_REF] Sztefko | Blood loss from laboratory diagnostic tests in children[END_REF][START_REF] Vincent | Anemia and Blood Transfusion in Critically Ill Patients[END_REF][START_REF] Stevens | Epidemiology and management of painful procedures in children in Canadian hospitals[END_REF][START_REF] Slifer | Distraction, Exposure Therapy, Counterconditioning, and Topical Anesthetic for Acute Pain Management During Needle Sticks in Children With Intellectual and Developmental Disabilities[END_REF][START_REF] Trottier | La gestion de la douleur et de l'anxiété chez les enfants lors de brèves interventions diagnostiques et thérapeutiques[END_REF][START_REF] Frasca | Reliability of the HemoCue® hemoglobinometer in critically ill patients[END_REF][START_REF] Seguin | Determination of capillary hemoglobin levels using the HemoCue system in intensive care patients[END_REF][START_REF] Shamir | The Current Status of Continuous Noninvasive Measurement of Total, Carboxy, and Methemoglobin Concentration[END_REF]. Demographic and clinical characteristics are summarized in Table 1.

Figure 2. Flowchart

Table 1. Characteristics of the study participants.

Overall, the mean LabHb was 10.0 g/dl (± 2.1) whereas mean SpHb was 11.6 g/dl (± 1.5). The mean difference between the two was 1.6 g/dl (± 1.3). The overall correlation study showed a Pearson coefficient of 0.77(0,7-0,8) (p < 0.001). Correlations at admission, H12, H24, H48 and H72 ranged from 0.66 to 0.9, and all were significant. However, at H6, the correlation was non-significant (p = 0.064) with r = 0.60 (-0.03 -0.89) (Table 2). When adjusted to the admission reason, the correlation between SpHb and LabHb remained significant (p < 0.001) with : r = 0.7 (0.4 -0.8) in patients admitted after an arthrodesis, r = 0.8 (0.6 -0.9) in patients monitored after an abdominal trauma and r = 0.7 (0.5 -0.9) in other patients (Appendix 1).

Linear regression was then used to explore the relationship between the two measures, finding a statistically significant association (p < 0.001) with a coefficient of R 2 = 0.6 (Figure 3). We also examined the number of SpHb readings within 0-1, 1-2, 2-3 and > 3 g/dl of LabHb measurements (Table 3). It appeared that only one third SpHb readings were actually within 1 g/dl of the LabHb measurement, and approximately 60% were within 2 g/dl (Table 3). Table 3. The percentage of patients at each 1g/dl interval difference between LabHb and SpHb measurements.

Bland-Altman analysis showed that most of the differences were within the limits of agreement, with the upper limit (+ 1,96 SD) being 1,1 g/dl and the lower limit (-1,96 SD) being -4,2 g/dl (Figure 4). Bland-Altman analysis and linear regressions were also performed at each time of measurement (admission, H6, H12, H24, H48 and H72). Details are available in Appendix. Forty-one patients in our cohort had a double pair of SpHb and LabHb values, allowing us to perform a trend study. For this trend study, we chose to look at the difference between two SpHb measurements at two different times in the same patient and compare it to the difference between the two LabHb measurements using the Bland & Altman analysis. The bias between difference means was 0,3 g/dl (± 1.3), IC95% (-0.1; 0.7). Bland-Altman analysis wasn't significant (p =0,13) with the upper agreement limit (+ 1,96 SD) being 2,8 g/dl and the lower limit (-1,96 SD) being -2,2 g/dl (Figure 5).

Discussion

This study is the first to evaluate the accuracy of trend of SpHb when compared to LabHb a high-risk of bleeding PICU cohort. This study showed that SpHb is probably able to display the true Hb trend with a mean difference of -0.3 +/-1.3, IC95% (-0.1 ;0.7). On the other hand, the extent of the limits of agreement calls into question the precision of the system, and hence its reliability in clinical practice. In this study, SpHb even highly correlated to LabHb appeared inaccurate to predict true Hb.

A few pediatric studies have previously analyzed the accuracy and concordance of this measurement method, but most of them only involved healthy children or ones in perioperative situations [START_REF] Arai | Evaluation of the use of noninvasive hemoglobin measurement in early childhood[END_REF][START_REF] Wittenmeier | Comparison of the gold standard of hemoglobin measurement with the clinical standard (BGA) and noninvasive hemoglobin measurement (SpHb) in small children: a prospective diagnostic observational study. Bosenberg A, éditeur[END_REF][START_REF] Park | The Accuracy of Noninvasive Hemoglobin Monitoring Using the Radical-7 Pulse CO-Oximeter in Children Undergoing Neurosurgery[END_REF][START_REF] Patino | Trending and Accuracy of Noninvasive Hemoglobin Monitoring in Pediatric Perioperative Patients[END_REF][START_REF] Nakamori | Postoperative Noninvasive Hemoglobin Monitoring Is Useful to Prevent Unnoticed Postoperative Anemia and Inappropriate Blood Transfusion in Patients Undergoing Total Hip or Knee Arthroplasty: A Randomized Controlled Trial[END_REF]. Three prospective observational studies have evaluated this device in PICU patients [START_REF] Akyildiz | Noninvasive Measurement of Hemoglobin Using Spectrophotometry: Is it Useful for the Critically Ill Child?[END_REF][START_REF] García-Soler | Monitorización no invasiva transcutánea de la concentración de hemoglobina en pacientes críticos pediátricos con riesgo de sangrado[END_REF][START_REF] Phillips | A noninvasive hemoglobin monitor in the pediatric intensive care unit[END_REF]. The method used and the population studied in these three cohorts are similar to ours, except for age. The median age in our study is significantly higher. These studies and their results are summarized in table 4.

Table 4: Summary of the main studies conducted on SpHb in PICU

Every study showed a good correlation between SpHb and LabHb (r = 0,55 (0.38 -0.68) [START_REF] Phillips | A noninvasive hemoglobin monitor in the pediatric intensive care unit[END_REF]; r = 0.69 (0.55 -0.78) [START_REF] García-Soler | Monitorización no invasiva transcutánea de la concentración de hemoglobina en pacientes críticos pediátricos con riesgo de sangrado[END_REF]). However, these three studies found a lower mean difference between SpHb and LabHb (0.07 g/dl [START_REF] Phillips | A noninvasive hemoglobin monitor in the pediatric intensive care unit[END_REF], 0.66 g/dl [START_REF] García-Soler | Monitorización no invasiva transcutánea de la concentración de hemoglobina en pacientes críticos pediátricos con riesgo de sangrado[END_REF] and 0.84 g/dl (16) vs 1.6 g/dl in our study). This higher difference is not consistent with the technical specifications announced by the manufacturer of 1 g/dl maximum [START_REF]RD rainbow SET-2 Operator's manual[END_REF]. This result could be due to the SpHb measurement technique. Indeed, the sensor was left in place to allow continuous monitoring with automatic reading, which was not the case in the other studies, and it may have altered the measurements (too much light, sensor poorly positioned or detached, interference, etc) [START_REF]RD rainbow SET-2 Operator's manual[END_REF]. However, we believe that this is a more pragmatic approach and appropriate reflection of the device's use in a PICU.

In addition, this continuous installation of the sensor enabled us to systematically obtain a SpHb measurement within an hour of each blood test, which is a strength of our study. In comparison, Garcia-soler et al. failed to obtain a value in 5.2% of cases ( 17) and Phillips et al. had a rate of undetectable readings of 35% [START_REF] Phillips | A noninvasive hemoglobin monitor in the pediatric intensive care unit[END_REF]. Among other factors likely to affect the accuracy of transcutaneous monitoring, we found greater differences when LabHb levels were particularly low. Although anemia is not specifically mentioned, the device leaflet describes haemoglobinopathies as a potential cause of errors in SpHb reading. This is consistent with other studies that shown worse correlations with extreme LabHb values [START_REF] Phillips | A noninvasive hemoglobin monitor in the pediatric intensive care unit[END_REF][START_REF] Jung | The Efficacy of Noninvasive Hemoglobin Measurement by Pulse CO-Oximetry in Neonates[END_REF].

The trend study we carried out did not find any significant difference and does not allow us to conclude on the reliability of the continuous nature of the monitoring. It is therefore possible that SpHb is not mistaken in following the evolution of LabHb. However, the limits of agreement are important, which is in favor of a poor precision of SpHb measurements. It also showed that patients monitored for high hemorrhagic risk showed little bleeding during their stay. In fact, the mean LabHb difference for the same patient was -0.2g/dl and the median sensor installation time two days, which is shorter than the median length of stay (3 days). Indeed, hemoglobin monitoring seems to have been stopped earlier than expected in our study, probably due to the absence of bleeding in the patients. This finding raises the question of the timing of hemoglobin monitoring, and perhaps of excessive sampling.

We should acknowledge certain limitations. First, it is a retrospective, monocentric study involving a small population. Secondly, we did not investigate potential confounding factors whereas Philips et al. showed that an increased BMI or skin pigmentation affected the degree of concordance [START_REF] Phillips | A noninvasive hemoglobin monitor in the pediatric intensive care unit[END_REF]. Effects of HR and SpO2 variations were studied by Paksu et al. and no significant change of the correlation was found in healthy children [START_REF] Paksu | Reliability of spot-check transcutaneous hemoglobin measurement in children[END_REF]. A linear regression study including demographic and clinical data would be useful to target the most appropriate population that could benefit from SpHb monitoring. Thirdly, we did not take into account the economic aspects of using SpHb instead of, or in addition to, laboratory analysis of blood samples. Indeed, the cost of SpHb monitoring is not negligible (95 euros per sensor) whereas the current cost for a complete blood count (CBC) in our institution is 5.20 euros, which means that the device would have to substitute for several LabHb tests to be cost-effective. One previous study involving children undergoing neurosurgery reported that such device could be used to monitor trends in Hb levels and help clinical decision-making regarding the need and timing of LabHb testing [START_REF] Park | The Accuracy of Noninvasive Hemoglobin Monitoring Using the Radical-7 Pulse CO-Oximeter in Children Undergoing Neurosurgery[END_REF]. Another study demonstrated that the use of the SpHb monitoring resulted in fewer intraoperative blood transfusions during orthopedic surgeries in adults, offsetting the cost of the device [START_REF] Ehrenfeld | Impact of continuous and noninvasive hemoglobin monitoring on intraoperative blood transfusions[END_REF]. A similar prospective study should be conducted to demonstrate the costeffectiveness of the device in the PICU. Despite a good correlation, our study does not allow us to define an exact role for SpHb due to a lack of precision. Two meta-analyses, mainly involving studies with adult patients, reported that this technology is not sufficiently accurate to be used as the only indicator of transfusion and clinicians should be cautious when making clinical decisions made on it [START_REF] Kim | Accuracy of Continuous Noninvasive Hemoglobin Monitoring: A Systematic Review and Meta-Analysis[END_REF][START_REF] Rice | Noninvasive Hemoglobin Monitoring: How Accurate Is Enough?[END_REF]. Our study supports these conclusions.

Conclusion

This study shows good correlation between SpHb obtained with the Masimo sensor and LabHb, in the PICU setting. However, there is a non-negligible bias between the 2 measurements, with a mean difference of 1.6 g/dl, which seems to increase for very low hemoglobin values. This bias is higher than that of previous studies and the one announced by the manufacturer. The value of continuous hemoglobin monitoring could not be demonstrated by our study, with a non-significant trend analysis. Target populations and clinical contexts for safe and effective use of the device have yet to be properly defined. Future studies are needed to precisely determine the potential factors altering its functioning and estimate its cost-benefit ratio, taking particular account of its potential impact on transfusion savings.

  LabHb : hemoglobin measured in the laboratory PICU : pediatric intensive care units PIM : pediatric index of mortality SD : standard deviation SpHb : noninvasive hemoglobin monitoring by spectrophotometry SpO2 : oxygen saturation

Figure 1 :Figure 2 :Figure 3 :

 123 Figure 1: Hemoglobin monitoring protocol used in our PICU Figure 2: FlowchartFigure 3: Scatterplot of LabHb and SpHb values.

Figure 4 :

 4 Figure 4: Bland-Altman analysis for SpHb versus LabHb.

Figure 5 :

 5 Figure 5: Bland-Altman analysis for trend study

Sommaire 1 PréambuleL

 1 Préambule ......................................................................................................................... Introduction ...................................................................................................................... Materials and methods .................................................................................................... Results .............................................................................................................................. Discussion ...................................................................................................................... Conclusion ..................................................................................................................... References ...................................................................................................................... Appendices ..................................................................................................................... 'oxymétrie de pouls a été découverte en 1971 par Takuo Aoyagi lorsqu'il étudiait la mesure non invasive du débit cardiaque à l'aide d'une technique de dilution de colorant. Depuis, l'oxymétrie de pouls est devenue la technologie de monitoring la plus couramment utilisée car elle permet la mesure de plusieurs variables : la saturation en oxygène de l'hémoglobine, la fréquence cardiaque pulsée mais aussi le rythme cardiaque. Son utilisation à grande échelle a permis de développer des méthodes de mesure non invasive concernant d'autres caractéristiques sanguines et notamment la concentration en hémoglobine. L'analyse conventionnelle en laboratoire de la concentration d'hémoglobine est réalisée à l'aide d'un spectrophotomètre et est basée sur la loi de Lambert-Beer. Cette loi stipule que la quantité d'intensité lumineuse absorbée par une solution est appelée "absorbance" (A) et qu'elle est directement proportionnelle :

  Cette relation peut être exprimée comme suit : Α = 𝜀𝑑𝑐 L'hémoglobinomètre de laboratoire crée d'abord une suspension d'hémoglobine en hémolysant un petit échantillon de sang dans un puit, éliminant ainsi l'absorption de la lumière par la membrane de l'érythrocyte. Une lumière d'une longueur d'onde et d'une intensité connue est ensuite diffusée à travers le puit contenant la suspension d'hémoglobine. Enfin, l'intensité de la lumière transmise est mesurée. Comme toutes les propriétés physiques du puit et de la lumière sont connues, la concentration d'hémoglobine peut ainsi être calculée car il s'agit de l'unique inconnue selon la loi de Lambert-Beer.

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  La taille du doigt change, d'un doigt à l'autre et d'une personne à l'autre, ce qui rend la longueur du trajet optique variable. Masimo (Irvine, CA) a introduit la technologie SET (Signal Extraction Technology) pour améliorer la précision de l'oxymétrie de pouls à 2 longueurs d'ondes dans des conditions de mouvement et de faible perfusion. Elle comprend des filtres, des capteurs protégés de la lumière et des radiofréquences, et des algorithmes de traitement numérique. La technologie Rainbow SET de Masimo a été introduite en 2008 (ajout de nombreuses longueurs d'ondes) pour mesurer les concentrations totales d'hémoglobine, de méthémoglobine et de carboxyhémoglobine. Au sein de notre unité, nous utilisons ce dispositif de surveillance non invasive de l'hémoglobine développé par Masimo, et tel que décrit précédemment depuis 2021. Nous avons choisi de réaliser une étude concernant son utilisation dans un service de réanimation pédiatrique. Ce travail de thèse a été rédigé selon un format article en anglais et présente les résultats de nos recherches.

  This study was approved by the Local Research Ethics Committee for health research of the University Hospital of Caen on 23/06/2022 (ID 3517). The Institutional Review Board waived the need for informed consent. Population Patients under 18 years old at admission in the PICU and requiring SpHb monitoring during their stay were included. Patients weighing less than 3 kilograms, or with hemodynamic instability, defined as the use of noradrenaline above 0.25 mcg/kg/min and/or inotropes, or missing data, or whose parents opposed the use of the data for any retrospective study were excluded.

Figure 1 .

 1 Figure 1. Hemoglobin monitoring protocol used in our PICU CBC: Cell blood count, H: Hour

  Median age was 13.1 years [7 months -17.9 years] and median weight was 47 kg [8.5 -86]. Most patients were admitted for monitoring after abdominal trauma (40%) or arthrodesis (36%). Other reasons (24%) were: open fracture, digestive hemorrhage, postoperative craniostenosis. The median PIM score on admission was 0.4 [0.1 -6]. Five patients were on ventilatory support and only two patients required aminergic support. The median duration of sensor placement was two days

Figure 3 .

 3 Figure 3. Scatterplot of LabHb and SpHb values. The solid line is the regression line.

Figure 4 .

 4 Figure 4. Bland-Altman analysis for SpHb versus LabHb. Each dot indicates the bias of a single patient at a specific time point.

Figure 5 .

 5 Figure 5. Bland-Altman analysis for trend study. Each dot indicates the bias between difference means of a single patient.

Table 1 :

 1 Characteristics of the study participants.

Table 2 :

 2 Correlation between LabHb and SpHb according to the time of measurement.

Table 3 :

 3 The percentage of patients at each 1g/dl interval difference between LabHb and

	SpHb measurements

Table 4 :

 4 Summary of the main studies conducted on SpHb in PICU

Table 2. Correlation between LabHb and SpHb according to the time of measurement.

Remerciements

RESUME DE LA THESE EN FRANÇAIS : Introduction : La surveillance de l'hémoglobine dans les services de réanimation pédiatrique est un véritable enjeu. L'utilisation d'une méthode de mesure non invasive permettrait de répondre aux contraintes spécifiques d'une population pédiatrique telles que les difficultés de prélèvement ou la spoliation sanguine. Une technique de mesure par co-oxymétrie de pouls existe mais son utilisation en réanimation pédiatrique est controversée. Notre étude a pour but d'évaluer la corrélation et les tendances entre les valeurs d'hémoglobine estimées par méthode non invasive (SpHb) et celles mesurées par le laboratoire (LabHb). Matériel et méthodes : Nous avons réalisé une étude rétrospective observationnelle sur une cohorte de 52 patients âgés de 6 mois à 18 ans, présentant un risque hémorragique élevé, hospitalisés en réanimation pédiatrique. Résultats : 109 paires de valeurs SpHb/LabHb ont pu être étudiées. Les valeurs moyennes de LabHb et SpHb étaient de 10 g/dL et de 11,6 g/dL respectivement. Les résultats montrent une bonne corrélation avec un coefficient de Pearson r = 0,77 (0,7-0,8) (p<0,001). L'analyse de Bland-Altman montre une différence moyenne de 1,6g/dL ± 2,64g/dL, avec seulement 60% des valeurs de SpHb ayant une différence de moins de 2g/dL par rapport à LabHb. L'étude des tendances est non significative (p=0,13) avec une différence moyenne de 0,3g/dL ± 1,3g/dL IC 95% (-0,1-0,7). Conclusion : SpHb présente une bonne corrélation avec LabHb. Cependant, ce dispositif de surveillance manque de précision et son utilité en monitorage continu n'est pas démontré. Des études supplémentaires doivent préciser la population cible et le contexte clinique adéquat. MOTS CLES : Hémoglobine ; anémie ; surveillance non invasive ; Unité de soins intensif pédiatrique ; Oxymétrie. TITRE DE LA THESE EN ANGLAIS : Evaluation of non-invasive hemoglobin measurement in pediatric intensive care units.

RESUME DE LA THESE EN ANGLAIS :

Introduction: Hemoglobin monitoring in pediatric intensive care units is a real challenge. The use of a noninvasive measurement method would make it possible to respond to the specific constraints of a pediatric population, such as sampling difficulties or blood spoliation. A pulse co-oximetry measurement technique exists, but its use in pediatric intensive care is controversial. The aim of our study is to evaluate the correlation and trends between hemoglobin values estimated by non-invasive methods (SpHb) and those measured by the laboratory (LabHb). Material and methods: We carried out a retrospective observational study on a cohort of 52 patients aged 6 months to 18 years at high risk of bleeding, hospitalized in pediatric intensive care. Results: 109 pairs of SpHb/LabHb values were studied. Mean LabHb and SpHb values were 10 g/dL and 11.6 g/dL respectively. The results show a good correlation with a Pearson coefficient r = 0.77 (0.7-0.8) (p<0.001). Bland-Altman analysis shows a mean difference of 1.6g/dL ± 2.64g/dL, with only 60% of SpHb values having a difference of less than 2g/dL from LabHb. Trend analysis was non-significant (p=0.13), with a mean difference of 0.3g/dL ± 1.3g/dL 95% CI (-0.1-0.7). Conclusion: SpHb correlates well with LabHb. However, this monitoring device lacks precision and its usefulness in continuous monitoring has not been demonstrated. Further studies are needed to define the target population and the appropriate clinical context. KEY WORDS: hemoglobin; anemia; non-invasive monitoring; pediatric intensive care unit; oximetry.


est destinée au dépôt

Experimental and numerical study of fire spread on a wooden façade

Context and Objectives

Wood has become one of the key elements of modern construction. However, wood remains a very reactive material, which implies a higher risk in terms of fire safety. To understand the different aspects of façade fires, a national project called FIREWALL+ has been launched in France. The main objectives of the FIREWALL+ project are to answer some fundamental questions about the main mechanisms that control fire propagation, the interaction between the flow and the façade, etc. In order to answer these questions, medium and large-scale experiments have been conducted, establishing a detailed database. These experiments will then be used to validate existing numerical codes, in the present work FireFOAM 1 was used. Afterwards, these numerical tools will be used to study more complex phenomena that cannot be adressed experimentally.

• Material: Spruce • Dimensions: 150 x 53 x 5 cm 3

• Fire source: Radiant panel 50 x 50 cm located 20 cm from the wood panel with a 50 kW heat release rate. • Instrumentation:

• Weighing scale • Two heat flux meters (total and radiative)

• Oxygen consumption hood • Infrared camera • In-depth temperature measurement 2
(20 thermocouples)

A.Experimental configuration B. Results

Bouaza LAFDAL 1 , Romain MEINIER 1 , Lucas TERREI 1 , Gilles PARENT 1 , Zoubir ACEM 1 , Rabah MEHADDI 1 , Pascal BOULET 1 and Arnaud TROUVÉ 2 Contactbouaza.lafdal@univ-lorraine.fr

Experimental study

• Heat release rate (HRR)

• Good agreement between HRR measured by oxygen consumption and HRR calculated based on mass loss rate. • Heat of combustion ranges from 13 MJ/kg to 18 MJ/kg

• Heat flux at the panel surface

• The convective heat flux is determined from the differences between total and radiative heat flux. • In the early stages, heat transfer is dominated by convection.

• The radiative heat flux is practically constant, while the convective heat flux decreases.

• In-depth temperature • In-depth temperature profiles were provided by thermocouples embedded within the sample. Here, the 300 °C isotherm is presented, which is known to correspond to the char front position. • At the end of the test, the panel had lost 1.4198 kg of its initial mass (the degraded surface is 70 cm high and 53 cm wide), i.e. an average char front thickness of 8.5 mm. A similar value is found based on the temperature measurements (slightly more than 10 mm).

  Experimental and numerical study of fire spread on a wooden façade Bouaza Lafdal, Romain Meinier, Lucas Terrei, Gilles Parent, Zoubir Acem, Rabah Mehaddi, Pascal Boulet, Arnaud Trouvé To cite this version: Bouaza Lafdal, Romain Meinier, Lucas Terrei, Gilles Parent, Zoubir Acem, et al.. Experimental and numerical study of fire spread on a wooden façade. IAFSS, Oct 2023, Tsukuba, France. 162, 2021. hal-04454710

Fig. 3 .Fig. 2 .

 32 Fig.3. Variation of the in-depth temperature [°C]

Fig. 1 .Fig. 5 .Fig. 6 .

 156 Fig.1. Evolution of the HRR

Fig. 7 .

 7 Fig.7. Comparison between the experimental and predicted mass loss rate (left) and the heat release rate

•

  This work was conducted as part of the FIREWALL+ project • High Performance Computing resources were partially provided by the EXPLOR center hosted by the University de Lorraine


Gaël Potin

Shabtay Ateret
email: ateret.shabtay-yanai@univ-reunion.fr

Lagabrielle Erwann

Potin Gaël

Guyomard David

Marine spatial planning provides a comprehensive framework for building evidence-based shark risk management policies with sea-users

Keywords: Marine spatial planning, Shark risk management, Human-wildlife interactions

Marine spatial planning provides a comprehensive framework for building evidence-based shark risk management policies with sea-users

Ateret Shabtay, Erwann Lagabrielle, Virginie Plot,

Introduction

Marine spatial planning (MSP) is a political process that aims to bring multiple ocean users to negotiate informed and coordinated decisions about the sustainable future use of marine resources [START_REF] Ehler | Marine spatial planning, a step-by-step approach towards ecosystem-based management[END_REF]. Being useful for realizing the ecosystem approach by analyzing and allocating human activities in the marine space, MSP initiatives are applied in about 70 countries around the world, which face multiple and various challenges (MSP Programme IOC-UNESCO, 2019; [START_REF] Santos | Chapter 30 -Marine Spatial Planning[END_REF]. Moreover, MSP mechanisms and principles has been integrated within the legal framework of several countries including the EU member states [START_REF] Ec | Directive 2014/89/EU of the European Parliament and of the Council of 23 July 2014 establishing a framework for maritime spatial planning[END_REF].

The theory and practice of MSP have significantly developed in the past decade and adapted to new challenges. The growing concern to marine ecosystems and impacts of climate change, along with increasing human activity at sea, drove this evolution and demonstrated the adaptability of the MSP framework (e.g., [START_REF] Gissi | Incorporating change in marine spatial planning: A review[END_REF][START_REF] Santos | Ocean planning in a changing climate[END_REF][START_REF] Young | Building the Blue Economy: The Role of Marine Spatial Planning in Facilitating Offshore Renewable Energy Development[END_REF][START_REF] Zanuttigh | A methodology for multi-criteria design of multi-use offshore platforms for marine renewable energy harvesting[END_REF]. The ability of MSP to adapt to new challenges might therefore be useful also for planning the management of specific human-wildlife interactions at sea.

Although most of those interactions result in threat to wildlife, some interactions such as shark bites on humans receive significant attention. Shark bite events in the past 30 years were recorded in more than 50 countries, most of them (83%) in United States, Australia, South Africa, Brazil, and Reunion Island (ISAF, 2019). Despite being a global phenomenon, fatality rates of unprovoked shark bite are relatively low (average of <10 people per year globally) (ISAF, 2019). Yet, public response to these events is often impacting local economies due to following reduction in marine recreation activities and tourism [START_REF] Lemahieu | Humanshark interactions: The case study of Reunion island in the south-west Indian Ocean[END_REF][START_REF] Simmons | Shark management strategy policy considerations: Community preferences, reasoning and speculations[END_REF]. In addition, shark risk management that involves shark removal often triggers disputes regarding management's effectiveness and its impact on marine ecosystems. Therefore, shark risk and its related management should be addressed from holistic perspective within an interdisciplinary framework that considers the ecological and social aspect of it (Lagabrielle et al., 2018a).

In the present study, we use MSP as a backbone structure to frame shark risk and its related management within the wider scope of managing multiple human activities in the marine space. We suggest an approach for integrating shark risk into MSP-related spatial analyses, consultation processes, and decision-making. The approach identifies the social and ecological issues related to spatial overlap between humans and sharks, and supply a solid ground for negotiations regarding shark risk management allocation.

We first explore how human-wildlife interactions are referred to in spatial planning and how shark risk is managed, to prescribe an adjusted and relevant MSP approach that addresses shark risk within a broader social-ecological scope. Then, we apply the prescribed methodology on an MSP process in Reunion Island (France, Indian Ocean), where the rate of lethal shark bite events is one of the world's highest (ISAF, 2019).

Integrating shark risk management into MSP

Human-wildlife interactions and spatial planning

Threats to humans as a result of human-wildlife interactions are rarely addressed through spatial planning and especially not in the marine environment. In most cases, planning considers human impact on wildlife and not the other way around. As evidence are the numerous tools and approaches developed in the past decade to use planning for mitigating threats to wildlife caused by human activities and to ensure ecosystembased management [START_REF] Lombard | Practical Approaches and Advances in Spatial Tools to Achieve Multi-Objective Marine Spatial Planning[END_REF][START_REF] Pınarbaşı | Decision support tools in marine spatial planning: Present applications, gaps and future perspectives[END_REF]. Therefore, using MSP to address threat to humans as a result of human-wildlife interactions, may require adoption of perspective that captures both the ecological and social dimensions of those interactions, across time and spatial scales.

A key step towards understanding the complexities of conflicting human-wildlife interactions, is exploring their related social factors . [START_REF] Dickman | Complexities of conflict: the importance of considering social factors for effectively resolving human-wildlife conflict[END_REF] suggests that human-wildlife conflicts represent conflicts between social groups with antagonistic opinions. Planners and authorities who direct MSP and who are usually familiar with social conflicts in general but less with specific human-wildlife conflicts, can therefore use their skills to investigate social factors related to human-wildlife interaction, to initiate conflict's mitigation process.

Stakeholders and public participation in MSP processes is an opportunity to investigate social conflicts about human-wildlife interactions. A broad-scoped public consultation can reach beyond antagonistic debates about these interactions and develop an understanding of the mental representations involved. The consultation process can also be used to estimate the extent and intensity of the conflict which is needed to determine whether sufficient grounds for negotiation exist (The Consensus Building Institute, 2000). Thus, understanding the stakes and history of the conflict, and identifying social groups in early stages, may direct the organization of stakeholders' interactions within the MSP process at later stages.

Shark risk management

Shark risk management is applied where events of unprovoked shark bite occurred several times, in attempt to reduce the probability of their occurrence. Management measures include warning and education, surveillance, at-sea devices such as lethal shark nets and drumlines, exclusion shark nets, and personal electromagnetic devices for sea users. The effectiveness of these measures is still unclear despite their constant assessment by scientists and management authorities [START_REF] Clua | Individual shark profiling: An innovative and environmentally responsible approach for selectively managing human fatalities[END_REF]CSR, 2017;[START_REF] Curtis | Responding to the risk of White Shark attack[END_REF][START_REF] Guyomard | An innovative fishing gear to enhance the release of non-target species in coastal shark-control programs: The SMART (shark management alert in real-time) drumline[END_REF]. Especially controversial is whether management effectiveness in terms of reducing risk to humans worth its impact on marine ecosystems [START_REF] Atkins | Net loss of endangered humpback dolphins: integrating residency, site fidelity, and bycatch in shark nets[END_REF][START_REF] Epa | EPA recommends Shark Hazard Mitigation Drum Line proposal should not be implemented[END_REF][START_REF] Gibbs | Transforming shark hazard policy: Learning from ocean-users and shark encounter in Western Australia[END_REF]. Moreover, impacted by the reaction of people to the risk, management is often an adaptive, sometime erratic, process that responds to random variations in locations of shark bite events, changing legislations, instruments availability, social tolerance to the risk, and social acceptance of the management [START_REF] Gibbs | Transforming shark hazard policy: Learning from ocean-users and shark encounter in Western Australia[END_REF][START_REF] Pepin-Neff | Shark Bites and Shark Conservation: An Analysis of Human Attitudes Following Shark Bite Incidents in Two Locations in Australia[END_REF][START_REF] Pepin-Neff | Considering Sharks from a Post-Jaws Perspective, Flaws: Shark Bites and Emotional Public Policymaking[END_REF][START_REF] Simmons | Shark management strategy policy considerations: Community preferences, reasoning and speculations[END_REF]. Therefore, shark risk management is often applied under condition of uncertainty and remains a matter of social controversies.

Addressing shark risk through marine spatial planning

The random character of the risk and the ad hoc, emotion-driven, character of shark risk management policies is a challenge for MSP which is a long and wide process that considers multiple marine uses, their long-term development stakes and environmental impacts at once. Still, the integration of shark risk management into MSP may contribute to better conceptualizing and contextualizing the risk, its management, and the associated social representations.

We suggest that shark risk and related management should be conceptualized within a three components framework (Figure 1). The first component is the ecological system, its structure and dynamics that might influence shark presence and might be impacted as a result of shark risk management. The second component is the social system with stakeholders and social groups of opinions, building up representations of the issue and competing to influence shark risk management. The third component is the geographic area of interaction where the ecological system and the social system meet. In this geographic area human-shark interactions may result in a threat to people, sharks, or ecosystems as a whole. The management of this area is a stake of negotiations in the social system and therefore in the MSP process. At the same time, MSP can be conceptualized as a framework to shape shark risk management public policy, and address social demand in a sustainable way. MSP which is embedded within a robust legal framework, might also enable the public policy to be negotiated and implemented. The three components of the interaction can be addressed using tools and consultation processes that are often being used in MSP as presented in Figure 2. Directing those tools towards shark risk and related management, will advance the understanding of the multicomponent nature of the shark-risk issue and the dependencies that may exist between these components. Sharks play an important ecological role in marine ecosystems and therefore human activities primarily designed for sharks' removal, have considerable potential for negatively impacting marine ecosystems [START_REF] Ferretti | Patterns and ecosystem consequences of shark declines in the ocean[END_REF]. Therefore, impact assessment in the MSP process should include an overlap of shark risk management with areas prioritized for marine conservation and direct impact of shark risk management on sharks' populations and other taxa (e.g. bycatch of shark control operations or wildlife entangled in shark nets, see [START_REF] Atkins | Humpback dolphin bycatch in the shark nets in KwaZulu-Natal, South Africa[END_REF]. Ideally, the indirect impact on the ecosystem should be assessed as well. Ecological modelling and especially food-web modelling could be highly useful for these assessments [START_REF] Shabtay | Using ecological modelling in marine spatial planning to enhance ecosystem-based management[END_REF].

Case-study: Integrating shark risk and related management into MSP in

Reunion Island

Study site

Reunion Island is a French volcanic island in the Southwestern Indian Ocean (21°07'S/55°32'E) with an overall area of 2512 km 2 . After rapid population growth since 1980, the island inhabits today about 860,000 people. The majority of the population resides along the coasts of the island and especially along the most urbanized northern and western coasts.

Shark risk management

Shark bite events have been known throughout the history of Reunion Island. However, the frequency of these events has increased dramatically by a factor of 23 since 2010 with 25 events of shark-bite that resulted in 11 fatalities up to this day (CSR, 2019a; Lagabrielle et al., 2018a). The majority of bite events was of surfers (i.e. wave-based activities) and caused by bull sharks (Carcharhinus leucas) and tiger sharks (Galeocerdo cuvier). The causes for the increased frequency of shark-bite events are still unclear to scientists.

Yet, studies suggested that among the potential causes are changes in sea water temperature, increased freshwater and sewage discharge along the west coast, and changes in shark's behavior due to degradation of prey populations including depletion of reef sharks by overfishing [START_REF] Chapman | Global shark attack hotspots: Identifying underlying factors behind increased unprovoked shark bite incidence[END_REF]Lagabrielle et al., 2018a). Furthermore, [START_REF] Guyomard | SMART drumlines at Réunion Island do not attract bull sharks Carcharhinus leucas into nearshore waters: Evidence from acoustic monitoring[END_REF] suggest that ban on sharks' finning and sharks' meat selling due to ciguatera concern, decreased sharks' fishing and therefore increased potentially dangerous sharks' abundance along the coasts. (see also [START_REF] Guyomard | Témoignages des usagers du milieu marin réunionnais sur les pêches et observations de requins depuis les dernières décennies[END_REF][START_REF] Manach | Reconstruction of the domestic and distantwater fisheries catch of La Réunion (France), 1950-2010[END_REF]. In addition, Thiann-Bo Morel (2019) presented social groups debated ideas about the causes of this increased frequency that include the establishment of a coastal marine protected area (MPA) in 2007.

Following a series of shark bite events in 2011, shark risk management measures were developed to reduce the risk. In 2013, the local government released a prefectural decree (Arrêté préfectoral n°222 du 15 février 2018, 2018) that bans bathing and wavebased activities along most of the island's coasts up to a distance of 300 m from the shore. The ban is excluding areas of shallow lagoons, coastal pool, and areas of surveillance. Since 2014, preventive shark control is operated and targeting individuals of bull shark and tiger shark that approach the coast. Control operations include lethal horizontal longline and SMART drumline devices [START_REF] Guyomard | SMART drumlines at Réunion Island do not attract bull sharks Carcharhinus leucas into nearshore waters: Evidence from acoustic monitoring[END_REF]. Later, in 2015, two large shark exclusion nets totalizing ~1km length were placed at two locations to allow surfing and bating activities, but are no longer operational due to unsustainable maintenance costs. Yet, 3 smaller nets for bathing remained operational.

At the same time, an innovative in-situ surveillance program was launched along the west coast of the island. Surveillance operations include in-water observers, water crafts, and a beach-based team that provides emergency response in case of shark observation or shark bite event. Both, exclusion nets and surveillance operations are located in 5 designated areas named ZONEXs (zone for experimental shark risk management measures) and are distributed along the west coast of the island.

Since 2016, shark risk management in the island is developed and coordinated primarily by Le Centre Sécurité Requin (CSR), which is a boundary organization placed under the authority of the state, regional council and municipalities. Daily information on shark management are accessible on http://www.info-requin.re, but no spatially explicit longterm analysis and synthesis of this information has been developed and released to the public so far.

Marine Spatial Planning process: The Ocean Metiss project

In Reunion Island, the on-going MSP process, named Ocean Metiss (see https://www.oceanmetiss.re, 2019), aims to develop a sustainable, integrated, longterm maritime development strategy and to implement it through a marine spatial plan of the exclusive economic zone of the island. Ocean Metiss is a partnership project co-funded by the European Maritime and Fisheries Fund, France state, and Reunion Island regional council. The interdisciplinary project is associating with the University of Reunion for its implementation, and the Indian Ocean Commission as a technical partner. From a European Commission perspective, Ocean Metiss is a pilot-project aiming to investigate innovative MSP processes, tools and methods that will facilitate the implementation of the European Directive on MSP (EC, 2014).

Methods

The Ocean Metiss project serves as a backbone structure for developing and testing our approach for addressing shark risk in MSP and designing MSP-based shark risk management, throughout the five planning stages as presented in Figure 2 and Table 1. Stakeholders explore alternative management options, using an online tool for collaborative planning. This stage is expected to be finalized at the end of the consultation process in August 2020. Limited biomass data and planning resources did not allow using ecological modelling in the current planning cycle.

Seasketch

Stage 4-Implement, manage and assess 4.1. Implement shark risk management spatial plan as part of the broader marine spatial plan. 4.2. Assess spatial plan. This stage is expected to be executed from September 2020. ArcMap version 10.2 Policy instruments a Activities exposed to shark risk were assumed to be any type that includes the immersion of the human body in the water, meaning bathing, diving, wave-based activities (hereafter = surfing), and wind-based activities. Freediving and spearfishing were also considered as activities exposed to risk, yet they were not investigated due to lack of updated data on their spatial distribution around the island. All activities exposed to risk are operated from the coast or from small boats. b Shark risk management include ZONEXs (where shark nets and surveillance operations are implemented), and preventive shark control (drumlines and longlines). c Due to limited data on sharks' species distribution around the island, we assumed sharks' presence in the entire area of interest. d Preventive shark control operations were excluded from this analysis due to high level of uncertainty associated to its impact on the risk. 246

Results

Stage 0

Along the cycle of MSP conferences, the "sharks" theme, was identified by the stakeholders as one of the major themes of the MSP process. (Figure 3). The theme was found to be linked to several other themes by 17 causative or impacting factors. Out of all the linked themes, the greatest number of links to the "sharks" theme was to tourism (6) and fishing (3). it (the larger and central the node, the more links it has). The width of the line represents the number of links that were identified between two nodes. The node that represents the "sharks" theme and the links between shark's theme and other themes are highlighted in blue.

Identification of social groups involved in the shark risk debate significantly profited from the study of Thiann-Bo [START_REF] Morel | Tensions entre justice environnementale et justice sociale en société postcoloniale: le cas du risque requin[END_REF]. She identifies surfers and their supporters in Reunion Island as a social group claiming sharks' removal in addition to other management measures. The study also sheds light on the complex context of the conflict to ethno-racial issues in a post-colonial community and environmental inequalities. The results of this study are also echoed by a survey which follows the work of [START_REF] Gibbs | Transforming shark hazard policy: Learning from ocean-users and shark encounter in Western Australia[END_REF] and is currently being processed by Lagabrielle (2019, unpublished) with support from the CSR. The preliminary results confirm that the main disagreements are between surfers and other sea users and revolve around shark removal policy. This study also shows the consensus among groups of users about other non-lethal shark management measures, including unanimous opposition against the decree that bans bathing around the island. The social component of shark risk and shark risk management in Reunion Island was also translated by [START_REF] Dupéré | L'évaluation du risque requin et la détermination des orientations de sa gestion. Perspectives judiciaires franco-mauriciennes[END_REF] into legal basis for integrating shark risk into marine spatial planning.

Stages 1 and 2

In spatial terms, all activities exposed to shark risk besides freediving and spearfishing take place in an overall area of 23 km 2 , most of it along the west coast of the island. About 60% of this area is within an MPA (Figure 4). Regularly, shark risk management is applied in ZONEXs areas which include surveillance, and shark nets, in an area of 1.1 km 2 . In addition, preventive shark control is applied regularly but in changing locations, and concentrated along the west coast of the island.

The latest preventive shark control program was released in May 2018 and lists areas where preventive shark control is regularly applied. In the first seven months of the program 155 bull sharks and tiger sharks were removed (CSR, 2019b). Since the beginning of preventing shark control operations in January 2014 until November 2019, a total area of 31.3 km 2 was used, 28% of it within MPA. Out of the 9559 drumline and longline devices which were deployed during that period, 3121 were deployed within zones 1 and 609 within zone 2B of the MPA where professional fishing including preventive shark control is permitted. Deployments of devices at the edges of zones 2A of the MPA where fishing is prohibited are recorded as well (130 devices), yet are assumed to be unintentional or due to unprecise location reporting (Figure 5A). Along this period, the number of devices per planning unit (100x100 m) where preventive shark control was applied varied between 1 and 376 (Figure 5B). Most (70%) of the devices were deliberately located within 1 km of activity exposed to risk, which reflects management objective of targeting sharks that frequent areas of activities exposed to risk. Surfing activity which is considered to be most exposed to shark risk is practiced along 3.2 km 2 , 24% of this area is within ZONEXs (Figures 4 and6). Therefore, 2.4 km 2 (76% of the surfing area) is still being used for surfing in an area banned for surfing by the prefectural decree (yet, at least 10 times less frequently than before 2011; see Lagabrielle et al. 2018a). Attempts to identify and assess the ecological impact of shark risk management faced difficulties due to significant data gaps. Most gaps are related to the biology, ecology, and behavior of bull sharks and tiger sharks in the area. However, others relate to the impact of management on the ecosystem and the effectiveness of the management in decreasing the risk. While some gaps are a consequence of data scarcity, others might emerge from poor synthesis or lack of data communication. Table 2 presents the main data gaps which were identified in this study and the implications they might have on planning.

Stage 3

Stage 3 of the planning process is currently being implemented and is expected to be completed by August 2020. Seasketch online zoning negotiation platform is currently being used (http://reunion.seasketch.org, 2019). The platform allows participation of stakeholders and sea users that can comment on existing data and propose spatial management planning scenarios (Figure 7). Those scenarios involve alternative zoning options for nautical activities exposed to shark risk and shark risk management measures. The platform includes more than 100 data layers of various environmental features and marine uses. The CSR aims to use Seasketch to design territorial management of shark risk. They expect it to improve the zoning of their actions, and to facilitate interactions and negotiations with stakeholders being impacted by shark risk management.

Discussion

The increased use in MSP framework to promote sustainable development around the world, reveals various interactions between human and marine ecosystems. In our study we disassembled the human-shark interaction that is primarily described as potentially dangerous for human, and acknowledged its multicomponent nature. We demonstrate that the MSP framework has the ability of addressing shark risk when it reaches beyond spatial solutions to the conflict. The MSP process can then be used in that case to design public policies related to shark risk through comprehensive, inclusive, and transparent consultation processes.

Targeting social debates within the framework of MSP, could be constrained by time and other planning resources such as knowledge and funding. Especially, intense social conflicts related to shark risk may require use of conflict mitigation tools which are not commonly applied in MSP (e.g. [START_REF] Hanssen | The Role of Ecological Science in Environmental Policy Making from a Pacification toward a Facilitation Strategy[END_REF][START_REF] Peltonen | Integrating impact assessment and conflict management in urban planning: Experiences from Finland[END_REF]. In this case, the contribution of MSP to conflict's mitigation might be hindered but could initiate and drive forward a process of mitigation that use social-conflict-oriented tools as a preparatory step for MSP [START_REF] Lecourt | Planning conflicts and social proximity: a reassessment[END_REF][START_REF] Oteros-Rozas | Participatory scenario planning in place-based social-ecological research: insights and experiences from 23 case studies[END_REF].

Alternatively, instead of trying to mitigate the conflict, effort could be directed towards providing the practice and institutions that allow conflicts to take an agonist form and make the conflicts explicit in the process as management issues [START_REF] Albrechts | Ingredients for a more radical strategic spatial planning[END_REF][START_REF] Nursey-Bray | More than fishy business": epistemology, integration and conflict in marine spatial planning[END_REF]. This radical planning approach that was originally suggested as an urban planning approach by [START_REF] Grabow | Foundations for a Radical Concept of Planning[END_REF], is not common in MSP process, but it may benefit from the significant driving force of conflicts to enhance social capacity as suggested by Nursey-Bray (2016).

Understanding the ecological impact of shark risk management could also be a challenge under the constrains of planning resources. The lack of sharks' ecological data results in high uncertainty regarding the effectiveness of management measures. The ability of MSP to account for the ecological dimension of the conflict is therefore depended on the existence of environmental data, how data reflect the interconnectivity between ecosystem components, and how it is translated into policy if at all.

In cases where shortfalls in data exist, we suggest that data gaps and related uncertainties should be strongly emphasized in the MSP process. This could direct resources towards biological and ecological research, which can be used for plan adaptation in the next planning cycles. We also suggest that those research products can be used for shark risk management strategy design in cases where the MSP is also used as a platform to construct shark risk public policy.

The results of this study suggest that MSP process is an opportunity to set guidelines for conflict mitigation when proposing a spatial marine plan (Table 3). Overall, those guidelines highlight the need to zone shark risk management, define target of each zone, and assure that areas developed for recreation will include the spatial requirements of shark risk management. Zoning of shark risk management can also be used to minimize or avoid overlap with other uses in cases of uncertainty such as overlap with MPAs. Evaluation of the marine plan can refer to the degree in which those guidelines are met.

Reunion Island case study demonstrates a rapid evolution of shark risk management that responded to sudden increase in a number of shark bite events in an unplanned environment. Shark risk management strategy that was and still being developed in "aswe-go" mode was spatially oriented mostly by the locations of activities exposed to risk and of shark bite events (see Section 3.2 and CSR, 2017; [START_REF] Guyomard | An innovative fishing gear to enhance the release of non-target species in coastal shark-control programs: The SMART (shark management alert in real-time) drumline[END_REF]. As a result, management measures such as preventive shark control and shark nets are located in or in proximity to an MPA which hosts most of the area of recreational activities around the island and which was primarily allocated to protect coral reef ecosystem. Although lack of evidence of a conflict between the MPA and shark risk management was found, significant data gaps were identified regarding the impact of shark risk management on the marine environment (see Table 2). Therefore, we suggest that the coexistence of these uses should be carefully considered in light of this high uncertainty.

Conclusions

The first attempt to address shark risk and its management through the MSP process, suggests that significant weight should be given to shark risk when considering development of sectors and designing public participation in decision makings. Framing of the risk and of the management in terms of space, people, and impact on ecosystem is a big step towards mainstreaming shark risk into transparent and participative decision making. This may balance both social responses to shark risk and the impact of management on the marine ecosystem.

The ability of MSP to adapt to new challenges and shed light on issues that are more than merely spatial overlaps of uses, allows the process to effectively address socioecological conflicts such as human-shark interactions. Even if complex decision support tools or analysis tools are not being used in the process, MSP can still reveal social and ecological aspects of uses and suggest systematic solutions. These solutions eventually contribute to sustainable development and ecosystem-based management which are in the heart of the recent worldwide legislations such as the European Directive for MSP [START_REF] Ec | Directive 2014/89/EU of the European Parliament and of the Council of 23 July 2014 establishing a framework for maritime spatial planning[END_REF].

We suggest that the approach proposed in this study could be adopted by other MSP initiatives worldwide where shark risk management is applied, and that it could encompass various management measures and social groups. Yet, we suggest that local knowledge and personal as possible consultation process would best promote sustainable solutions to shark risk and therefore, when applied to large marine areas or to heavily populated regions, the approach should be adapted accordingly (for example, by graduating the process or applying it to sub-regions). -Protection of bathing or surfing zone by nets/ surveillance.

-Removing specific individuals (such as adults vs. juveniles, males vs. females, daily vs. nightly catches, bull vs. tiger sharks, etc.) in attempt to control the presence of sharks or reduce immediate threat to sea users while minimizing impact on population or ecosystem. -Allocating multiuse areas of activities and shark risk management (e.g. surveillance or shark nets in bathing or surfing sites).

Coupling

-Creating buffer zones dedicated to shark risk management around popular areas of recreation activities while considering management limitations (e.g. depth and currents).

-Allocating coastal zones for warning against shark risk (signs, alerts etc.) and preparedness for shark bite events, such as medical cabin in popular recreation sites.

Minimizing impact on ecosystem

Uncertainty regarding impact on ecosystem should prevent or at least restrict and minimize allocation of shark risk management in proximity to vulnerable habitats.

-Excluding preventive shark control and shark nets from MPA areas.

-Expanding, reallocating, adapting the regulation or rezoning MPA 427 6. Acknowledgments

Figure 1 .

 1 Figure 1. The three components of socioecological interaction, the challenges they pose for MSP (black text) and how they are addressed through MSP (gray text).

Figure 2 .

 2 Figure 2. Tools and consultation processes that can be used throughout the marine spatial planning process to address the social, spatial, and ecological components of human-shark interaction. Simplified version of marine spatial planning stages (Ehler and Douvere, 2009) is adopted from Lagabrielle et al. (2018b).

Figure 3 .

 3 Figure 3. Thematic analysis of MSP drivers as viewed by the stakeholders. Each node represents a theme and lines represent link between themes in the form of cause or impact. The size and position of the node represent the number of other nodes linked to

Figure 4 .

 4 Figure 4. Recreation activities exposed to shark risk in Reunion Island

Figure 5 .

 5 Figure 5. Shark risk management around the island and along the west coast. A. Location of ZONEXs and preventive shark control devices deployed between January 2014 and November 2019 in relation to MPAs. B. PSC effort (per 100x100 m planning unit). MPA= marine protected area, ZONEX= area where shark risk management is constant and includes bathing nets and surveillance. PSC= preventive shark control device (drumlines and horizontal longlines).

Figure 6 .

 6 Figure 6. Preventive shark control (PSC) effort, overlap with MPA, and surfing within and outside ZONEXs, presented in 1x1 km grid around the island.

Figure 7 .

 7 Figure 7. Using Seasketch tool in marine spatial planning to promote collaborative process and address shark risk.

  344

Table 1 .

 1 Applying the integrative approach for marine spatial planning and shark risk in Ocean Metiss project, following Ehler and Develop and negotiate a spatial plan for shark risk management (among a set of optional spatial plans) in the broader framework of a multisectorial marine spatial plan. 3.2. Propose guidelines for spatial mitigation of the risk and of risk management impact on ecosystem.

	244
	245	Douvere (2009) planning stages.
		Planning stage	Objectives	Methods

Table 2 .

 2 Data gaps and sources for uncertainty identified when addressing shark risk and its management through MSP in Reunion 342 Island. Available and missing data refer to local data only.

	343
	Topic Available data	Missing data	Uncertainty to	Data sources
				account for in MSP
		• Partial data on bull shark	• Sharks' population size	• Exposure of users	The CHARC program (2015)
		population and their	and structure (sex ratio,	to sharks'	The ECoReCo-Run program
		presence along the island	average age etc.) *.	presence in an	(2017)
	Sharks' ecology and biology	tiger sharks. • Bull and tiger sharks are both considered apex west coast and along the year. • Partial data on trophic ecology, reproductive biology, population dynamics, and behavioral ecology of bull sharks and genetics, population	quality, climate change, prey population). • Trends in consumption • Sharks' species distribution around the entire island. • Trends in sharks' trends (e.g. water distribution and use of • Drivers of distribution habitat*.	area. • Cumulative long-term impact of uses on marine ecosystem.	Blaison et al. (2015) (Trystram et al., 2016) (Pirog et al., 2017) (Pirog et al., 2019a) Pirog et al. (2019c) Pirog et al. (2019b)
		predators, yet they	and production*
		demonstrate different	(biomass, prey, and
		foraging niches.	predators).

Table 3 .

 3 Guidelines for spatially mitigating human-shark conflict in MSP

	426
		Guidelines	Examples
	Zoning shark	Setting management targets. Each zone should
	risk	address specific target or risk. Management
	management	type and intensity should differ from one zone
		to another according to zone's targets.

Funding: This work was supported by the Reunion Island regional council, the European Commission, and the European Maritime and Fisheries Fund (grant EASME/EMFF/2016/1.2.1.6/04/SI2.766484). We would like to thank Ocean Metiss team at the Reunion Island regional council and especially to A. Szegvari-Mas for their cooperation and stakeholders' meetings organization. We would also like to thank Le Centre Sécurité Requin (CSR) for their cooperation, and especially to S. Jaquemet for his comments on earlier version of this manuscript. Finally, we thank W. McClintock and