Evolution structurale et métamorphique des nappes lyciennes et du massif du Menderes (Sud-Ouest de la Turquie) (implications géodynamiques et corrélations avec le domaine égéen)

L'Anatolie occidentale, prolongement vers l'est du domaine égéen, est constituée de plusieurs unités tectono-métamorphiques au sein desquelles affleurent des roches de haute-pression/basse température (HP-BT). Si certaines d'entre elles sont des vestiges des orogenèses Pan-Africaine et Cimmérienne, d'autres témoignent de l'orogenèse Alpine. Au Sud-Ouest de la Turquie, le massif du Menderes forme un large domaine chevauché au Nord par les unités de la zone de suture d'Izmir-Ankara, à l'Est par la Zone d'Afyon, et au Sud par les nappes lyciennes. Ce travail de thèse a permis de mettre en évidence l'existence de paragenèses à Fe-Mg-carpholite largement distribuées dans les sédiments des nappes lyciennes, ainsi que dans les séries de couverture de la partie la plus méridionale du massif du Menderes. Cette découverte révèle que ces deux complexes de nappes ont enregistré des conditions de HP-BT pendant l'orogenèse Alpine. Les conditions P-T du pic de métamorphisme sont de 10-12 kbar/400ʿC pour les nappes lyciennes, et de 12-14 kbar/470-500ʿC pour le massif du Menderes, ce qui correspond à un enfouissement d'au moins 30 km pendant le processus de subduction et d'empilement de nappes. L'analyse de la déformation ductile couplée à des calculs thermobarométriques basés sur la notion d'équilibres multiples indique que les métasédiments des nappes lyciennes ont enregistré des chemins d'exhumation distincts après le pic de métamorphisme. Les roches situées loin du contact entre les nappes lyciennes et le massif du Menderes, là où les paragenèses de HP sont préservées, ont enregistré des chemins froids (décompression en refroidissement) accompagnés de cisaillements vers le NNE liés à là zone de cisaillement d'Akçakaya. Cette zone de localisation de la déformation est un contact intra-nappe qui a fonctionné pendant les premiers stades d'exhumation des roches de HP, dans le champ de stabilité de la Fe-Mg-carpholite. En revanche, les roches situées au contact avec le massif du Menderes, là où les paragenèses de HP sont totalement rétromorphosées en chlorite et mica, ont enregistré des chemins d'exhumation plus chauds (décompression avec réchauffement) associés à un cisaillement intense vers l'est. Cette déformation s'est produite postérieurement à la mise en place des nappes lyciennes vers le sud, et est contemporaine de la réactivation du contact 'massif du Menderes/nappes lyciennes' en une zone de cisaillement majeure (la zone de cisaillement de Gerit) le long de laquelle se sont exhumées les paragenèses de HP sous des gradients plus chauds...Western Anatolia that represents the eastward lateral continuation of the Aegean domain is composed of several tectono-metamorphic units showing occurrences of high-pressure/low-temperature (HP-LT) rocks. While some of these metamorphic rocks are vestiges of the Pan-African or Cimmerian orogenies, others are the result of the more recent Alpine orogenesis. In southwest Turkey, the Menderes Massif occupies an extensive area tectonically overlain by nappe units of the Izmir-Ankara Suture Zone in the north, the Afyon Zone in the east, and the Lycian Nappes in the south. In the present study, investigations in the metasediments of the Lycian Nappes and underlying southern Menderes Massif revealed widespread occurrences of Fe-Mg-carpholite-bearing rocks. This discovery leads to the very first consideration that both nappe complexes recorded HP-LT metamorphic conditions during the Alpine orogenesis. P-T conditions for the HP metamorphic peak are about 10-12 kbar/400ʿC in the Lycian Nappes, and 12-14 kbar/470- 500ʿC in the southern Menderes Massif, documenting a burial of at least 30 km during subduction and nappe stacking. Ductile deformation analysis in concert with multi-equilibrium thermobarometric calculations reveals that metasediments from the Lycian Nappes recorded distinct exhumation patterns after a common HP metamorphic peak. The rocks located far from the contact separating the Lycian Nappes and the Menderes Massif, where HP parageneses are well preserved, retained a single HP cooling path associated with top-to-the-NNE shearing related to the Akçakaya shear zone. This zone of strain localization is an intra-nappe contact that was active in the early stages of exhumation of HP rocks, within the stability field of Fe-Mg-carpholite. The rocks located close to the contact with the Menderes Massif, where HP parageneses are completely retrogressed into chlorite and mica, recorded warmer exhumation paths associated with top-to-the-E intense shearing. This deformation occurred after the southward emplacement of Lycian Nappes, and is contemporaneous with the reactivation of the 'Lycian Nappes-Menderes Massif contact as a major shear zone (the Gerit shear zone) that allowed late exhumation of HP parageneses under warmer conditions...ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Intensive care-related loss of quality of life and autonomy at 6 months post-discharge: Does COVID-19 really make things worse?

International audienceAbstract Objective To compare old patients hospitalized in ICU for respiratory distress due to COVID-19 with old patients hospitalized in ICU for a non-COVID-19-related reason in terms of autonomy and quality of life. Design Comparison of two prospective multi-centric studies. Setting This study was based on two prospective multi-centric studies, the Senior-COVID-Rea cohort (COVID-19-diagnosed ICU-admitted patients aged over 60) and the FRAGIREA cohort (ICU-admitted patients aged over 70). Patients We included herein the patients from both cohorts who had been evaluated at day 180 after admission (ADL score and quality of life). Interventions None. Measurements and main results A total of 93 COVID-19 patients and 185 control-ICU patients were included. Both groups were not balanced on age, body mass index, mechanical ventilation, length of ICU stay, and ADL and SAPS II scores. We modeled with ordered logistic regression the influence of COVID-19 on the quality of life and the ADL score. After adjustment on these factors, we observed COVID-19 patients were less likely to have a loss of usual activities (aOR [95% CI] 0.47 [0.23; 0.94]), a loss of mobility (aOR [95% CI] 0.30 [0.14; 0.63]), and a loss of ADL score (aOR [95% CI] 0.30 [0.14; 0.63]). On day 180, 52 (56%) COVID-19 patients presented signs of dyspnea, 37 (40%) still used analgesics, 17 (18%) used anxiolytics, and 14 (13%) used antidepressant. Conclusions COVID-19-related ICU stay was not associated with a lower quality of life or lower autonomy compared to non-COVID-19-related ICU stay

Characteristics, management, and prognosis of elderly patients with COVID-19 admitted in the ICU during the first wave: insights from the COVID-ICU study

International audienceBackground: The COVID-19 pandemic is a heavy burden in terms of health care resources. Future decision-making policies require consistent data on the management and prognosis of the older patients (> 70 years old) with COVID-19 admitted in the intensive care unit (ICU). Methods: Characteristics, management, and prognosis of critically ill old patients (> 70 years) were extracted from the international prospective COVID-ICU database. A propensity score weighted-comparison evaluated the impact of intubation upon admission on Day-90 mortality. Results: The analysis included 1199 (28% of the COVID-ICU cohort) patients (median [interquartile] age 74 [72–78] years). Fifty-three percent, 31%, and 16% were 70–74, 75–79, and over 80 years old, respectively. The most frequent comorbidities were chronic hypertension (62%), diabetes (30%), and chronic respiratory disease (25%). Median Clinical Frailty Scale was 3 (2–3). Upon admission, the PaO2/FiO2 ratio was 154 (105–222). 740 (62%) patients were intubated on Day-1 and eventually 938 (78%) during their ICU stay. Overall Day-90 mortality was 46% and reached 67% among the 193 patients over 80 years old. Mortality was higher in older patients, diabetics, and those with a lower PaO2/FiO2 ratio upon admission, cardiovascular dysfunction, and a shorter time between first symptoms and ICU admission. In propensity analysis, early intubation at ICU admission was associated with a significantly higher Day-90 mortality (42% vs 28%; hazard ratio 1.68; 95% CI 1.24–2.27; p < 0·001). Conclusion: Patients over 70 years old represented more than a quarter of the COVID-19 population admitted in the participating ICUs during the first wave. Day-90 mortality was 46%, with dismal outcomes reported for patients older than 80 years or those intubated upon ICU admission

Benefits and risks of noninvasive oxygenation strategy in COVID-19: a multicenter, prospective cohort study (COVID-ICU) in 137 hospitals

International audienceAbstract Rational To evaluate the respective impact of standard oxygen, high-flow nasal cannula (HFNC) and noninvasive ventilation (NIV) on oxygenation failure rate and mortality in COVID-19 patients admitted to intensive care units (ICUs). Methods Multicenter, prospective cohort study (COVID-ICU) in 137 hospitals in France, Belgium, and Switzerland. Demographic, clinical, respiratory support, oxygenation failure, and survival data were collected. Oxygenation failure was defined as either intubation or death in the ICU without intubation. Variables independently associated with oxygenation failure and Day-90 mortality were assessed using multivariate logistic regression. Results From February 25 to May 4, 2020, 4754 patients were admitted in ICU. Of these, 1491 patients were not intubated on the day of ICU admission and received standard oxygen therapy (51%), HFNC (38%), or NIV (11%) ( P < 0.001). Oxygenation failure occurred in 739 (50%) patients (678 intubation and 61 death). For standard oxygen, HFNC, and NIV, oxygenation failure rate was 49%, 48%, and 60% ( P < 0.001). By multivariate analysis, HFNC (odds ratio [OR] 0.60, 95% confidence interval [CI] 0.36–0.99, P = 0.013) but not NIV (OR 1.57, 95% CI 0.78–3.21) was associated with a reduction in oxygenation failure). Overall 90-day mortality was 21%. By multivariable analysis, HFNC was not associated with a change in mortality (OR 0.90, 95% CI 0.61–1.33), while NIV was associated with increased mortality (OR 2.75, 95% CI 1.79–4.21, P < 0.001). Conclusion In patients with COVID-19, HFNC was associated with a reduction in oxygenation failure without improvement in 90-day mortality, whereas NIV was associated with a higher mortality in these patients. Randomized controlled trials are needed