Variabilité de l index de résistance rénal et insuffisance rénale aiguë chez les patients en choc septique (Etude NORADIR)

L'insuffisance rénale aiguë (IRA) complique environ 50% des chocs septiques et est associée à un mauvais pronostic. L index de résistance rénal mesuré par échographie Doppler (IR) est utilisé pour prédire la survenue d une IRA et étudier l'hémodynamique rénale. Mais ses performances statistiques sont limitées par la multiplicité de ses déterminants. Nous avons donc étudié les variations de l IR en réponse à des variations de PAM, pour neutraliser l'effet de certains déterminants et étudier la vasoréactivité rénale. L hypothèse était que le rapport IR/ PAM à J1 (différence de valeurs d IR mesurés à 2 niveaux de PAM divisée par la différence entre ces 2 niveaux de PAM) pourrait mieux prédire la survenue d une IRA. Il s'agissait d'une étude prospective observationnelle bicentrique. Les patients en choc septique et n'ayant pas d'insuffisance rénale chronique ont été inclus le jour de l admission en réanimation. Au moins 2 mesures de l IR étaient réalisées à 2 niveaux de PAM (le plus souvent pendant un relais de seringues de noradrénaline). La fonction rénale était évaluée à J3 (classification AKIN: groupe pas d IRA , AKIN 0 et 1, et groupe IRA , AKIN 2 et 3). Sur les 65 patients inclus, 35 présentaient une IRA à J3. L'IR à J1 était plus élevé dans le groupe IRA que dans le groupe pas d'IRA (0,73 [0,67-0,78] vs 0,67 [0,59-0,72], p=0,001). En revanche, le rapport IR/ PAM n était pas différent entre les 2 groupes (p=0,915). Un modèle linéaire mixte a montré que l'IR était prédit indépendamment par la fréquence cardiaque (FC), l IRA à J3, la PAM et la pression pulsée (PP) et que l'IRA à J3 ne modifiait pas les relations entre IR et PAM, IR et PP et IR et FC.ANGERS-BU Médecine-Pharmacie (490072105) / SudocSudocFranceF

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Target blood pressure in sepsis: between a rock and a hard place

International audienceThe optimal target blood pressure in septic shock is still unknown. Therefore, in a long-term, resuscitated porcine model of fecal peritonitis-induced septic shock, Correa and colleagues tested whether different titrations of mean arterial pressure (50 to 60 and 75 to 85 mm Hg) would produce different effects on sepsis-related organ dysfunction. The higher blood pressure window was associated with increased needs for fluid resuscitation and norepinephrine support. However, titrating the lower blood pressure range coincided with an increased incidence of acute kidney injury. In contrast, neither the inflammatory response nor tissue mitochondrial activity showed any difference. This research paper in a clinically relevant model elegantly demonstrates that any standard resuscitation strategy may be a double-edged sword with respect to various therapeutic endpoints. Furthermore, it adds an important piece to the puzzle of the complex pathophysiology of sepsis-related acute kidney injury.</p

Information conveyed by electrical diaphragmatic activity during unstressed, stressed and assisted spontaneous breathing: a physiological study

International audienceAbstract Background The electrical activity of the crural diaphragm (Eadi), a surrogate of respiratory drive, can now be measured at the bedside in mechanically ventilated patients with a specific catheter. The expected range of Eadi values under stressed or assisted spontaneous breathing is unknown. This study explored Eadi values in healthy subjects during unstressed (baseline), stressed (with a resistance) and assisted spontaneous breathing. The relation between Eadi and inspiratory effort was analyzed. Methods Thirteen healthy male volunteers were included in this randomized crossover study. Eadi and esophageal pressure (Peso) were recorded during unstressed and stressed spontaneous breathing and under assisted ventilation delivered in pressure support (PS) at low and high assist levels and in neurally adjusted ventilatory assist (NAVA). Overall eight different situations were assessed in each participant (randomized order). Peak, mean and integral of Eadi, breathing pattern, esophageal pressure–time product (PTPeso) and work of breathing (WOB) were calculated offline. Results Median [interquartile range] peak Eadi at baseline was 17 [13–22] μV and was above 10 μV in 92% of the cases. Eadi max defined as Eadi measured at maximal inspiratory capacity reached 90 [63 to 99] μV. Median peak Eadi/Eadi max ratio was 16.8 [15.6–27.9]%. Compared to baseline, respiratory rate and minute ventilation were decreased during stressed non-assisted breathing, whereas peak Eadi and PTPeso were increased. During unstressed assisted breathing, peak Eadi decreased during high-level PS compared to unstressed non-assisted breathing and to NAVA ( p = 0.047). During stressed breathing, peak Eadi was lower during all assisted ventilation modalities compared to stressed non-assisted breathing. During assisted ventilation, across the different conditions, peak Eadi changed significantly, whereas PTPeso and WOB/min were not significantly modified. Finally, Eadi signal was still present even when Peso signal was suppressed due to high assist levels. Conclusion Eadi analysis provides complementary information compared to respiratory pattern and to Peso monitoring, particularly in the presence of high assist levels. Trial registration The study was registered as NCT01818219 in clinicaltrial.gov. Registered 28 February 201

Reliability and limits of transport-ventilators to safely ventilate severe patients in special surge situations

International audienceBackground Intensive Care Units (ICU) have sometimes been overwhelmed by the surge of COVID-19 patients. Extending ICU capacity can be limited by the lack of air and oxygen pressure sources available. Transport ventilators requiring only one O-2 source may be used in such places. Objective To evaluate the performances of four transport ventilators and an ICU ventilator in simulated severe respiratory conditions. Materials and methods Two pneumatic transport ventilators, (Oxylog 3000, Draeger; Osiris 3, Air Liquide Medical Systems), two turbine transport ventilators (Elisee 350, ResMed; Monnal T60, Air Liquide Medical Systems) and an ICU ventilator (Engstrom Carestation-GE Healthcare) were evaluated on a Michigan test lung. We tested each ventilator with different set volumes (Vt(set) = 350, 450, 550 ml) and compliances (20 or 50 ml/cmH(2)O) and a resistance of 15 cmH(2)O/l/s based on values described in COVID-19 Acute Respiratory Distress Syndrome. Volume error (percentage of Vt(set)) with P-0.1 of 4 cmH(2)O and trigger delay during assist-control ventilation simulating spontaneous breathing activity with P-0.1 of 4 cmH(2)O and 8 cmH(2)O were measured. Results Grouping all conditions, the volume error was 2.9 +/- 2.2% for Engstrom Carestation; 3.6 +/- 3.9% for Osiris 3; 2.5 +/- 2.1% for Oxylog 3000; 5.4 +/- 2.7% for Monnal T60 and 8.8 +/- 4.8% for Elisee 350. Grouping all conditions (P-0.1 of 4 cmH(2)O and 8 cmH(2)O), trigger delay was 50 +/- 11 ms, 71 +/- 8 ms, 132 +/- 22 ms, 60 +/- 12 and 67 +/- 6 ms for Engstrom Carestation, Osiris 3, Oxylog 3000, Monnal T60 and Elisee 350, respectively. Conclusions In surge situations such as COVID-19 pandemic, transport ventilators may be used to accurately control delivered volumes in locations, where only oxygen pressure supply is available. Performances regarding triggering function are acceptable for three out of the four transport ventilators tested

Assessment of a massive open online course (MOOC) incorporating interactive simulation videos on residents’ knowledge retention regarding mechanical ventilation

International audienceBackground: Understanding respiratory physiology and mechanical ventilation is a challenge for healthcare workers, particularly, medical residents. A team of French-speaking experts developed an innovative MOOC incorporating interactive simulation-based videos and serious games aiming at improving knowledge and skills in mechanical ventilation. Our objective was to evaluate the long-term knowledge retention regarding key concepts presented in this MOOC. Methods: French residents registered for the MOOC 2020’s winter session were invited to participate in a two-step study. The first step consisted in evaluating students’ pre-course knowledge of respiratory physiology and mechanical ventilation fusing a 20 five-item multiple choice questions test with a total score ranging from 0 to 100. For the second step, the same students answered the same test (after shuffling the questions) six months after the completion of the course. We assessed the impact of this MOOC on the students’ knowledge retention by comparing pre-course and post-course scores. Result: Of the 102 residents who agreed to participate in the study, 80 completed the course and their mean ± SD pre-course score was 76.0 ± 8.0. Fifty-one respondents also completed the second and their post-course score was significantly higher than the baseline one (83.1 ± 7.3 vs. 77.5 ± 7.6, p < 0.001). Scores of the first and second rounds did not differ upon comparing respondents’ background specialty or number of years of residency. For the vast majority of individual questions (96%), the success rate was higher at the post-course than at the pre-course assessment. Conclusion: An innovative MOOC incorporating simulation-based videos was effective in teaching medical residents basic mechanical ventilation knowledge and skills, especially in the field of respiratory physiology and ventilatory modes. We observed effective long-term knowledge retention with a higher score at the post-course assessment six months after the completion of the course compared with the pre-course score

High flow nasal cannula improves breathing efficiency and ventilatory ratio in COPD patients recovering from an exacerbation

International audienc

Recruitability and effect of PEEP in SARS-Cov-2-associated acute respiratory distress syndrome

International audienceBACKGROUND:A large proportion of patients with a SARS-Cov-2-associated respiratory failure develop an acute respiratory distress syndrome (ARDS). It has been recently suggested that SARS-Cov-2-associated ARDS may differ from usual non-SARS-Cov-2-associated ARDS by higher respiratory system compliance (CRS), lower potential for recruitment with positive end-expiratory pressure (PEEP) contrasting with severe shunt fraction. The purpose of the study was to systematically assess respiratory mechanics and recruitability in SARS-Cov-2-associated ARDS.METHODS:Gas exchanges, CRS and hemodynamics were assessed at 2 levels of PEEP (15 cmH2O and 5 cmH2O) within 36 h (day1) and from 4 to 6 days (day 5) after intubation. The recruited volume was computed as the difference between the volume expired from PEEP 15 to 5 cmH2O and the volume predicted by compliance at PEEP 5 cmH2O (or above airway opening pressure). The recruitment-to-inflation (R/I) ratio (i.e. the ratio between the recruited lung compliance and CRS at PEEP 5 cmH2O) was used to assess lung recruitability. A R/I ratio value higher than or equal to 0.5 was used to define highly recruitable patients.RESULTS:The R/I ratio was calculated in 25 of the 26 enrolled patients at day 1 and in 15 patients at day 5. At day 1, 16 (64%) were considered as highly recruitable (R/I ratio median [interquartile range] 0.7 [0.55-0.94]) and 9 (36%) were considered as poorly recruitable (R/I ratio 0.41 [0.31-0.48]). The PaO2/FiO2 ratio at PEEP 15 cmH2O was higher compared to PEEP 5 cmH2O only in highly recruitable patients (173 [139-236] vs 135 [89-167] mmHg; p < 0.01). Neither PaO2/FiO2 or CRS measured at PEEP 15 cmH2O or at PEEP 5 cmH2O nor changes in PaO2/FiO2 or CRS in response to PEEP changes allowed to identify highly or poorly recruitable patients.CONCLUSION:In this series of 25 patients with SARS-Cov-2 associated ARDS, 64% were considered as highly recruitable and only 36% as poorly recruitable based on the R/I ratio performed on the day of intubation. This observation suggests that a systematic R/I ratio assessment may help to guide initial PEEP titration to limit harmful effect of unnecessary high PEEP in the context of Covid-19 crisis

Gas Exchange and Respiratory Mechanics After a Cardiac Arrest: A Clinical Description of Cardiopulmonary Resuscitation-Associated Lung Edema

International audienc

A novel method for assessment of airway opening pressure without the need for low-flow insufflation

Abstract Background Airway opening pressure (AOP) detection and measurement are essential for assessing respiratory mechanics and adapting ventilation. We propose a novel approach for AOP assessment during volume assist control ventilation at a usual constant-flow rate of 60 L/min. Objectives To validate the conductive pressure (P cond) method, which compare the P cond—defined on the airway pressure waveform as the difference between the airway pressure level at which an abrupt change in slope occurs at the beginning of insufflation and PEEP—to resistive pressure for AOP detection and measurement, and to compare its respiratory and hemodynamic tolerance to the standard low-flow insufflation method. Methods The proof-of-concept of the P cond method was assessed on mechanical (lung simulator) and physiological (cadavers) bench models. Its diagnostic performance was evaluated in 213 patients, using the standard low-flow insufflation method as a reference. In 45 patients, the respiratory and hemodynamic tolerance of the P cond method was compared with the standard low-flow method. Measurements and main results Bench assessments validated the P cond method proof-of-concept. Sensitivity and specificity of the P cond method for AOP detection were 93% and 91%, respectively. AOP obtained by P cond and standard low-flow methods strongly correlated (r = 0.84, p < 0.001). Changes in SpO2 were significantly lower during P cond than during standard method (p < 0.001). Conclusion Determination of P cond during constant-flow assist control ventilation may permit to easily and safely detect and measure AOP