Background Little information is available about the geo-economic variations in demographics, management, and outcomes of patients with acute respiratory distress syndrome (ARDS). We aimed to characterise the effect of these geo-economic variations in patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE). Methods LUNG SAFE was done during 4 consecutive weeks in winter, 2014, in a convenience sample of 459 intensivecare units in 50 countries across six continents. Inclusion criteria were admission to a participating intensive-care unit (including transfers) within the enrolment window and receipt of invasive or non-invasive ventilation. One of the trial's secondary aims was to characterise variations in the demographics, management, and outcome of patients with ARDS. We used the 2016 World Bank countries classification to define three major geo-economic groupings, namely European high-income countries (Europe-High), high-income countries in the rest of the world (rWORLD-High), and middle-income countries (Middle). We compared patient outcomes across these three groupings. LUNG SAFE is registered with ClinicalTrials.gov, number NCT02010073. Findings Of the 2813 patients enrolled in LUNG SAFE who fulfilled ARDS criteria on day 1 or 2, 1521 (54%) were recruited from Europe-High, 746 (27%) from rWORLD-High, and 546 (19%) from Middle countries. We noted significant geographical variations in demographics, risk factors for ARDS, and comorbid diseases. The proportion of patients with severe ARDS or with ratios of the partial pressure of arterial oxygen (PaO 2) to the fractional concentration of oxygen in inspired air (F I O 2) less than 150 was significantly lower in rWORLD-High countries than in the two other regions. Use of prone positioning and neuromuscular blockade was significantly more common in Europe-High countries than in the other two regions. Adjusted duration of invasive mechanical ventilation and length of stay in the intensive-care unit were significantly shorter in patients in rWORLD-High countries than in Europe-High or Middle countries. High gross national income per person was associated with increased survival in ARDS; hospital survival was significantly lower in Middle countries than in Europe-High or rWORLD-High countries. Interpretation Important geo-economic differences exist in the severity, clinician recognition, and management of ARDS, and in patients' outcomes. Income per person and outcomes in ARDS are independently associated.

BackgroundPredicting fluid responsiveness may help to avoid unnecessary fluid administration during acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate the diagnostic performance of the following methods to predict fluid responsiveness in ARDS patients under protective ventilation in the prone position: cardiac index variation during a Trendelenburg maneuver, cardiac index variation during an end-expiratory occlusion test, and both pulse pressure variation and change in pulse pressure variation from baseline during a tidal volume challenge by increasing tidal volume (VT) to 8 ml.kg-1.MethodsThis study is a prospective single-center study, performed in a medical intensive care unit, on ARDS patients with acute circulatory failure in the prone position. Patients were studied at baseline, during a 1-min shift to the Trendelenburg position, during a 15-s end-expiratory occlusion, during a 1-min increase in VT to 8 ml.kg-1, and after fluid administration. Fluid responsiveness was deemed present if cardiac index assessed by transpulmonary thermodilution increased by at least 15% after fluid administration.ResultsThere were 33 patients included, among whom 14 (42%) exhibited cardiac arrhythmia at baseline and 15 (45%) were deemed fluid-responsive. The area under the receiver operating characteristic (ROC) curve of the pulse contour-derived cardiac index change during the Trendelenburg maneuver and the end-expiratory occlusion test were 0.90 (95% CI, 0.80–1.00) and 0.65 (95% CI, 0.46–0.84), respectively. An increase in cardiac index ≥ 8% during the Trendelenburg maneuver enabled diagnosis of fluid responsiveness with sensitivity of 87% (95% CI, 67–100), and specificity of 89% (95% CI, 72–100). The area under the ROC curve of pulse pressure variation and change in pulse pressure variation during the tidal volume challenge were 0.52 (95% CI, 0.24–0.80) and 0.59 (95% CI, 0.31–0.88), respectively.ConclusionsChange in cardiac index during a Trendelenburg maneuver is a reliable test to predict fluid responsiveness in ARDS patients in the prone position, while neither change in cardiac index during end-expiratory occlusion, nor pulse pressure variation during a VT challenge reached acceptable predictive performance to predict fluid responsiveness in this setting.Trial registrationClinicalTrials.gov, NCT01965574. Registered on 16 October 2013. The trial was registered 6 days after inclusion of the first patient.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-017-1881-0) contains supplementary material, which is available to authorized users.

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BACKGROUND: Successful weaning from mechanical ventilation depends on the patient's ability to cough efficiently. Cough peak flow (CPF) could predict extubation success using a dedicated flow meter but required patient disconnection. We aimed to predict extubation outcome using an overall model, including cough performance assessed by a ventilator flow meter. METHODS: This was a prospective observational study conducted from November 2014 to October 2015. Before and after a spontaneous breathing trial, subjects were encouraged to cough as strongly as possible before freezing the ventilator screen to assess CPF and tidal volume (V T ) in the preceding inspiration. Early extubation success rate was defined as the proportion of subjects not re-intubated 48 h after extubation. Diagnostic performance of CPF and V T was assessed by using the area under the curve of the receiver operating characteristic curve. Cut-off values for CPF and V T were defined according to median values and used to describe the performance of a predictive test combining them with risk factors of early extubation failure. RESULTS: Among 673 subjects admitted, 92 had a cough assessment before extubation. For the 81 subjects with early extubation success, the median CPF was ؊67.7 L/min, and median V T was 0.646 L. For the 11 subjects with early extubation failure, the median CPF was ؊57.3 L/min, and median V T was 0.448 L. Area under the curve was 0.61 (95% CI 0.37-0.83) for CPF and 0.64 (95% CI 0.42-0.84) for CPF/V T combined. After dichotomization (CPF < ؊60 L/min or V T > 0.55 L), there was a synergistic effect to predict early extubation success (P < .001). The predictive value of success reached 94.2% for CPF/V T combined. The overall model including pH before extubation < 7.45 reached a 66.7% predictive value of failure. CONCLUSIONS: CPF measured using the flow meter of an ICU ventilator was able to predict extubation success and to build a composite score to predict extubation failure. The results were close to that found in previous studies that used a dedicated flow meter. This could help to identify high-risk subjects to prevent extubation failure. (ClinicalTrials.gov registration NCT02847221.)

Purpose: Mechanical ventilation with ultra-low tidal volume (VT) during ARDS may reduce alveolar strain, driving pressure and hence ventilator-induced lung injury, with the main drawback of worsening respiratory acidosis. We hypothesized that VT could be reduced down to 4 ml/kg, with clinically significant decrease in driving pressure, without the need for extracorporeal CO 2 removal, while maintaining pH > 7.20. Methods: We conducted a non-experimental before-and-after multicenter study on 35 ARDS patients with PaO 2 / FiO 2 ≤ 150 mmHg, within 24 h of ARDS diagnosis. After inclusion, VT was reduced to 4 ml/kg and further adjusted to maintain pH ≥ 7.20, respiratory rate was increased up to 40 min −1 and PEEP was set using a PEEP-FiO 2 table. The primary judgment criterion was driving pressure on day 2 of the study, as compared to inclusion. Results: From inclusion to day 2, driving pressure decreased significantly from 12 [9-15] to 8 [6-11] cmH 2 O, while VT decreased from 6.0 [5.9-6.1] to 4.1 [4.0-4.7] ml/kg. On day 2, VT was below 4.2 ml/kg in 65% [CI 95% 48%-79%], and below 5.25 ml/kg in 88% [CI 95% 74%-95%] of the patients. 2 patients (6%) developed acute cor pulmonale after inclusion. Eleven patients (32%) developed transient severe acidosis with pH < 7.15. Fourteen patients (41%) died before day 90. Conclusion: Ultra-low tidal volume ventilation may be applied in approximately 2/3 of moderately severe-to-severe ARDS patients, with a 4 cmH 2 O median reduction in driving pressure, at the price of transient episodes of severe acidosis in approximately 1/3 of the patients.

BackgroundIn acute respiratory distress syndrome (ARDS) patients, it has recently been proposed to set positive end-expiratory pressure (PEEP) by targeting end-expiratory transpulmonary pressure. This approach, which relies on the measurement of absolute esophageal pressure (Pes), has been used in supine position (SP) and has not been investigated in prone position (PP). Our purposes were to assess Pes-guided strategy to set PEEP in SP and in PP as compared with a PEEP/FIO2 table and to explore the early (1 h) and late (16 h) effects of PP on lung and chest wall mechanics.ResultsWe performed a prospective, physiologic study in two ICUs in university hospitals on ARDS patients with PaO2/FIO2 < 150 mmHg. End-expiratory Pes (Pes,ee) was measured in static (zero flow) condition. Patients received PEEP set according to a PEEP/FIO2 table then according to the Pes-guided strategy targeting a positive (3 ± 2 cmH2O) static end-expiratory transpulmonary pressure in SP. Then, patients were turned to PP and received same amount of PEEP from PEEP/FIO2 table then Pes-guided strategy. Respiratory mechanics, oxygenation and end-expiratory lung volume (EELV) were measured after 1 h of each PEEP in each position. For the rest of the 16-h PP session, patients were randomly allocated to either PEEP strategy with measurements done at the end. Thirty-eight ARDS patients (27 male), mean ± SD age 63 ± 13 years, were included. There were 33 primary ARDS and 26 moderate ARDS. PaO2/FIO2 ratio was 120 ± 23 mmHg. At same PEEP/FIO2 table-related PEEP, Pes,ee averaged 9 ± 4 cmH2O in both SP and PP (P = 0.88). With PEEP/FIO2 table and Pes-guided strategy, PEEP was 10 ± 2 versus 12 ± 4 cmH2O in SP and 10 ± 2 versus 12 ± 5 cmH2O in PP (PEEP strategy effect P = 0.05, position effect P = 0.96, interaction P = 0.96). With the Pes-guided strategy, chest wall elastance increased regardless of position. Lung elastance and transpulmonary driving pressure decreased in PP, with no effect of PEEP strategy. Both PP and Pes-guided strategy improved oxygenation without interaction. EELV did not change with PEEP strategy. At the end of PP session, respiratory mechanics did not vary but EELV and PaO2/FIO2 increased while PaCO2 decreased.ConclusionsThere was no impact of PP on Pes measurements. PP had an immediate improvement effect on lung mechanics and a late lung recruitment effect independent of PEEP strategy.Electronic supplementary materialThe online version of this article (10.1186/s13613-018-0434-2) contains supplementary material, which is available to authorized users.

BackgroundWe determined reliability of cardiac output (CO) measured by pulse wave transit time cardiac output system (esCCO system; COesCCO) vs transthoracic echocardiography (COTTE) in mechanically ventilated patients in the early phase of septic shock. A secondary objective was to assess ability of esCCO to detect change in CO after fluid infusion.MethodsMechanically ventilated patients admitted to the ICU, aged >18 years, in sinus rhythm, in the early phase of septic shock were prospectively included. We performed fluid infusion of 500ml of crystalloid solution over 20 minutes and recorded CO by EsCCO and TTE immediately before (T0) and 5 minutes after (T1) fluid administration. Patients were divided into 2 groups (responders and non-responders) according to a threshold of 15% increase in COTTE in response to volume expansion.ResultsIn total, 25 patients were included, average 64±15 years, 15 (60%) were men. Average SAPSII and SOFA scores were 55±21.3 and 13±2, respectively. ICU mortality was 36%. Mean cardiac output at T0 was 5.8±1.35 L/min by esCCO and 5.27±1.17 L/min by COTTE. At T1, respective values were 6.63 ± 1.57 L/min for esCCO and 6.10±1.29 L/min for COTTE. Overall, 12 patients were classified as responders, 13 as non-responders by the reference method. A threshold of 11% increase in COesCCO was found to discriminate responders from non-responders with a sensitivity of 83% (95% CI, 0.52-0.98) and a specificity of 77% (95% CI, 0.46-0.95).ConclusionWe show strong correlation esCCO and echocardiography for measuring CO, and change in CO after fluid infusion in ICU patients.

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