Restrictive use of Restraints and Delirium Duration in the Intensive Care Unit (R2D2-ICU): protocol for a French multicentre parallel-group open-label randomised controlled trial.

INTRODUCTION: Physical restraint (PR) is prescribed in patients receiving invasive mechanical ventilation in the intensive care unit (ICU) to avoid unplanned removal of medical devices. However, it is associated with an increased risk of delirium. We hypothesise that a restrictive use of PR, as compared with a systematic use, could reduce the duration of delirium in ICU patients receiving invasive mechanical ventilation. METHODS AND ANALYSIS: The Restrictive use of Restraints and Delirium Duration in ICU (R2D2-ICU) study is a national multicentric, parallel-group, randomised (1:1) open-label, controlled, superiority trial, which will be conducted in 10 ICUs. A total of 422 adult patients requiring invasive mechanical ventilation for an expected duration of at least 48 hours and eligible for prescription of PR will be randomly allocated within 6 hours from intubation to either the restrictive PR use group or the systematic PR use group, until day 14, ICU discharge or death, whichever comes first. In both groups, PR will consist of the use of wrist straps. The primary endpoint will be delirium or coma-free days, defined as the number of days spent alive in the ICU without coma or delirium within the first 14 days after randomisation. Delirium will be assessed using the Confusion Assessment Method-ICU twice daily. Key secondary endpoints will encompass agitation episodes, opioid, propofol, benzodiazepine and antipsychotic drug exposure during the 14-day intervention period, along with a core outcome set of measures evaluated 90 days postrandomisation. ETHICS AND DISSEMINATION: The R2D2-ICU study has been approved by the Comité de Protection des Personnes (CPP) ILE DE FRANCE III-PARIS (CPP19.09.06.37521) on June 10th, 2019). Participant recruitment started on 25 January 2021. Results will be published in international peer-reviewed medical journals and presented at conferences. TRIAL REGISTRATION NUMBER: NCT04273360.

Ultra-low tidal volume ventilation for COVID-19-related ARDS in France (VT4COVID): a multicentre, open-label, parallel-group, randomised trial.

BACKGROUND: COVID-19-related acute respiratory distress syndrome (ARDS) is associated with a high mortality rate and longer mechanical ventilation. We aimed to assess the effectiveness of ventilation with ultra-low tidal volume (ULTV) compared with low tidal volume (LTV) in patients with COVID-19-related ARDS. METHODS: This study was a multicentre, open-label, parallel-group, randomised trial conducted in ten intensive care units in France. Eligible participants were aged 18 years or older, received invasive mechanical ventilation for COVID-19 (confirmed by RT-PCR), had ARDS according to the Berlin definition, a partial pressure of arterial oxygen to inspiratory oxygen fraction (PaO2/FiO2) ratio of 150 mm Hg or less, a tidal volume (VT) of 6·0 mL/kg predicted bodyweight or less, and received continuous intravenous sedation. Patients were randomly assigned (1:1) using randomisation blocks to receive ULTV (intervention group) aiming for VT of 4·0 mL/kg predicted bodyweight or LTV (control group) aiming for VT 6·0 mL/kg predicted bodyweight. Participants, investigators, and outcome assessors were not masked to group assignment. The primary outcome was a ranked composite score based on all-cause mortality at day 90 as the first criterion and ventilator-free days among patients alive at day 60 as the second criterion. Effect size was computed with the unmatched win ratio, on the basis of pairwise prioritised comparison of primary outcome components between every patient in the ULTV group and every patient in the LTV group. The unmatched win ratio was calculated as the ratio of the number of pairs with more favourable outcome in the ULTV group over the number of pairs with less favourable outcome in the ULTV group. Primary analysis was done in the modified intention-to-treat population, which included all participants who were randomly assigned and not lost to follow-up. This trial is registered with ClinicalTrials.gov, NCT04349618. FINDINGS: Between April 15, 2020, and April 13, 2021, 220 patients were included and five (2%) were excluded. 215 patients were randomly assigned (106 [49%] to the ULTV group and 109 [51%] to the LTV group). 58 (27%) patients were female and 157 (73%) were male. The median age was 68 years (IQR 60-74). 214 patients completed follow-up (one lost to follow-up in the ULTV group) and were included in the modified intention-to-treat analysis. The primary outcome was not significantly different between groups (unmatched win ratio in the ULTV group 0·85 [95% CI 0·60 to 1·19]; p=0·38). 46 (44%) of 105 patients in the ULTV group and 43 (39%) of 109 in the LTV group died by day 90 (absolute difference 4% [-9 to 18]; p=0·52). The rate of severe respiratory acidosis in the first 28 days was higher in the ULTV group than in the LTV group (35 [33%] vs 14 [13%]; absolute difference 20% [95% CI 9 to 31]; p=0·0004). INTERPRETATION: In patients with moderate-to-severe COVID-19-related ARDS, there was no significant difference with ULTV compared with LTV in the composite score based on mortality and ventilator-free days among patients alive at day 60. These findings do not support the systematic use of ULTV in patients with COVID-19-related ARDS. FUNDING: French Ministry of Solidarity and Health and Hospices Civils de Lyon.

Bench Study of a Spontaneous Breathing Trial with Different Modalities.

BACKGROUND: The spontaneous breathing trial (SBT) is the final step of weaning from invasive mechanical ventilation. An SBT is aimed at predicting work of breathing (WOB) after extubation and, most importantly, a patient's eligibility for extubation. The optimal SBT modality remains debated. A high-flow oxygen (HFO) has been tested during SBT in clinical study only, which is why no definite conclusion can be drawn on its physiologic effects on the endotracheal tube. Our objective was to assess, on a bench, inspiratory tidal volume (VT), total PEEP, and WOB across 3 different SBT modalities: T-piece, 40 L/min HFO, and 60 L/min HFO. METHODS: A test lung model was set with 3 conditions of resistance and linear compliance, 3 inspiratory efforts (low, normal, and high), each at 2 breathing frequencies (low and high for 20 and 30 breaths/min, respectively). Pairwise comparisons and a quasi-Poisson generalized linear model that compared SBT modalities were performed. RESULTS: Inspiratory VT, total PEEP, and WOB differed from one SBT modality to another. Inspiratory VT remained higher with the T-piece than in the HFO independent of the mechanical condition, effort intensity, and breathing frequency (P < .001 in each comparison). WOB adjusted by the inspiratory VT was significantly lower during SBT performed with an HFO than when performed with the T-piece (P < .001 in each comparison). The total PEEP was significantly higher in the HFO at 60 L/min than in the other modalities (P < .001). The end points were significantly influenced by breathing frequency, effort intensity, and mechanical condition. CONCLUSIONS: With the same effort intensity and breathing frequency, inspiratory VT was higher in the T-piece than in the other modalities. Compared with the T-piece, WOB was significantly lower in the HFO condition and higher flow was a benefit. Based on the results of the present study, the HFO as an SBT modality would seem to require clinical testing.

Corticosteroids for severe acute exacerbations of chronic obstructive pulmonary disease in intensive care: From the French OUTCOMEREA cohort.

INTRODUCTION: Acute exacerbation of chronic obstructive pulmonary disease (COPD) is a frequent cause of intensive care unit (ICU) admission. However, data are scarce and conflicting regarding the impact of systemic corticosteroid treatment in critically ill patients with acute exacerbation of COPD. The aim of the study was to assess the impact of systemic corticosteroids on the occurrence of death or need for continuous invasive mechanical ventilation at day 28 after ICU admission. METHODS: In the OutcomeReaTM prospective French national ICU database, we assessed the impact of corticosteroids at admission (daily dose ≥ 0.5 mg/kg of prednisone or equivalent during the first 24 hours ICU stay) on a composite outcome (death or invasive mechanical ventilation) using an inverse probability treatment weighting. RESULTS: Between January 1, 1997 and December 31, 2018, 391 out of 1,247 patients with acute exacerbations of COPDs received corticosteroids at ICU admission. Corticosteroids improved the main composite endpoint (OR = 0.70 [0.49; 0.99], p = 0.044. However, for the subgroup of most severe COPD patients, this did not occur (OR = 1.12 [0.53; 2.36], p = 0. 770). There was no significant impact of corticosteroids on rates of non-invasive ventilation failure, length of ICU or hospital stay, mortality or on the duration of mechanical ventilation. Patients on corticosteroids had the same prevalence of nosocomial infections as those without corticosteroids, but more glycaemic disorders. CONCLUSION: Using systemic corticosteroids for acute exacerbation of COPD at ICU admission had a positive effect on a composite outcome defined by death or need for invasive mechanical ventilation at day 28.

Precision of CT-derived alveolar recruitment assessed by human observers and a machine learning algorithm in moderate and severe ARDS.

BACKGROUND: Assessing measurement error in alveolar recruitment on computed tomography (CT) is of paramount importance to select a reliable threshold identifying patients with high potential for alveolar recruitment and to rationalize positive end-expiratory pressure (PEEP) setting in acute respiratory distress syndrome (ARDS). The aim of this study was to assess both intra- and inter-observer smallest real difference (SRD) exceeding measurement error of recruitment using both human and machine learning-made lung segmentation (i.e., delineation) on CT. This single-center observational study was performed on adult ARDS patients. CT were acquired at end-expiration and end-inspiration at the PEEP level selected by clinicians, and at end-expiration at PEEP 5 and 15 cmH2O. Two human observers and a machine learning algorithm performed lung segmentation. Recruitment was computed as the weight change of the non-aerated compartment on CT between PEEP 5 and 15 cmH2O. RESULTS: Thirteen patients were included, of whom 11 (85%) presented a severe ARDS. Intra- and inter-observer measurements of recruitment were virtually unbiased, with 95% confidence intervals (CI95%) encompassing zero. The intra-observer SRD of recruitment amounted to 3.5 [CI95% 2.4-5.2]% of lung weight. The human-human inter-observer SRD of recruitment was slightly higher amounting to 5.7 [CI95% 4.0-8.0]% of lung weight, as was the human-machine SRD (5.9 [CI95% 4.3-7.8]% of lung weight). Regarding other CT measurements, both intra-observer and inter-observer SRD were close to zero for the CT-measurements focusing on aerated lung (end-expiratory lung volume, hyperinflation), and higher for the CT-measurements relying on accurate segmentation of the non-aerated lung (lung weight, tidal recruitment…). The average symmetric surface distance between lung segmentation masks was significatively lower in intra-observer comparisons (0.8 mm [interquartile range (IQR) 0.6-0.9]) as compared to human-human (1.0 mm [IQR 0.8-1.3] and human-machine inter-observer comparisons (1.1 mm [IQR 0.9-1.3]). CONCLUSIONS: The SRD exceeding intra-observer experimental error in the measurement of alveolar recruitment may be conservatively set to 5% (i.e., the upper value of the CI95%). Human-machine and human-human inter-observer measurement errors with CT are of similar magnitude, suggesting that machine learning segmentation algorithms are credible alternative to humans for quantifying alveolar recruitment on CT.

Response to PEEP in COVID-19 ARDS patients with and without extracorporeal membrane oxygenation. A multicenter case-control computed tomography study.

BACKGROUND: PEEP selection in severe COVID-19 patients under extracorporeal membrane oxygenation (ECMO) is challenging as no study has assessed the alveolar recruitability in this setting. The aim of the study was to compare lung recruitability and the impact of PEEP on lung aeration in moderate and severe ARDS patients with or without ECMO, using computed tomography (CT). METHODS: We conducted a two-center prospective observational case-control study in adult COVID-19-related patients who had an indication for CT within 72 h of ARDS onset in non-ECMO patients or within 72  h after ECMO onset. Ninety-nine patients were included, of whom 24 had severe ARDS under ECMO, 59 severe ARDS without ECMO and 16 moderate ARDS. RESULTS: Non-inflated lung at PEEP 5 cmH2O was significantly greater in ECMO than in non-ECMO patients. Recruitment induced by increasing PEEP from 5 to 15 cmH2O was not significantly different between ECMO and non-ECMO patients, while PEEP-induced hyperinflation was significantly lower in the ECMO group and virtually nonexistent. The median [IQR] fraction of recruitable lung mass between PEEP 5 and 15 cmH2O was 6 [4-10]%. Total superimposed pressure at PEEP 5 cmH2O was significantly higher in ECMO patients and amounted to 12 [11-13] cmH2O. The hyperinflation-to-recruitment ratio (i.e., a trade-off index of the adverse effects and benefits of PEEP) was significantly lower in ECMO patients and was lower than one in 23 (96%) ECMO patients, 41 (69%) severe non-ECMO patients and 8 (50%) moderate ARDS patients. Compliance of the aerated lung at PEEP 5 cmH2O corrected for PEEP-induced recruitment (CBABY LUNG) was significantly lower in ECMO patients than in non-ECMO patients and was linearly related to the logarithm of the hyperinflation-to-recruitment ratio. CONCLUSIONS: Lung recruitability of COVID-19 pneumonia is not significantly different between ECMO and non-ECMO patients, with substantial interindividual variations. The balance between hyperinflation and recruitment induced by PEEP increase from 5 to 15 cmH2O appears favorable in virtually all ECMO patients, while this PEEP level is required to counteract compressive forces leading to lung collapse. CBABY LUNG is significantly lower in ECMO patients, independently of lung recruitability.

Early prone positioning in acute respiratory distress syndrome related to COVID-19: a propensity score analysis from the multicentric cohort COVID-ICU network-the ProneCOVID study.

BACKGROUND: Delaying time to prone positioning (PP) may be associated with higher mortality in acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19). We evaluated the use and the impact of early PP on clinical outcomes in intubated patients hospitalized in intensive care units (ICUs) for COVID-19. METHODS: All intubated patients with ARDS due to COVID-19 were involved in a secondary analysis from a prospective multicenter cohort study of COVID-ICU network including 149 ICUs across France, Belgium and Switzerland. Patients were followed-up until Day-90. The primary outcome was survival at Day-60. Analysis used a Cox proportional hazard model including a propensity score. RESULTS: Among 2137 intubated patients, 1504 (70.4%) were placed in PP during their ICU stay and 491 (23%) during the first 24 h following ICU admission. One hundred and eighty-one patients (36.9%) of the early PP group had a PaO2/FiO2 ratio > 150 mmHg when prone positioning was initiated. Among non-early PP group patients, 1013 (47.4%) patients had finally been placed in PP within a median delay of 3 days after ICU admission. Day-60 mortality in non-early PP group was 34.2% versus 39.3% in the early PP group (p = 0.038). Day-28 and Day-90 mortality as well as the need for adjunctive therapies was more important in patients with early PP. After propensity score adjustment, no significant difference in survival at Day-60 was found between the two study groups (HR 1.34 [0.96-1.68], p = 0.09 and HR 1.19 [0.998-1.412], p = 0.053 in complete case analysis or in multiple imputation analysis, respectively). CONCLUSIONS: In a large multicentric international cohort of intubated ICU patients with ARDS due to COVID-19, PP has been used frequently as a main treatment. In this study, our data failed to show a survival benefit associated with early PP started within 24 h after ICU admission compared to PP after day-1 for all COVID-19 patients requiring invasive mechanical ventilation regardless of their severity.

Open-label randomized controlled trial of ultra-low tidal ventilation without extracorporeal circulation in patients with COVID-19 pneumonia and moderate to severe ARDS: study protocol for the VT4COVID trial.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a severe complication of COVID-19 pneumonia, with a mortality rate amounting to 34-50% in moderate and severe ARDS, and is associated with prolonged duration of invasive mechanical ventilation. Such as in non-COVID ARDS, harmful mechanical ventilation settings might be associated with worse outcomes. Reducing the tidal volume down to 4 mL kg-1 of predicted body weight (PBW) to provide ultra-low tidal volume ventilation (ULTV) is an appealing technique to minimize ventilator-inducted lung injury. Furthermore, in the context of a worldwide pandemic, it does not require any additional material and consumables and may be applied in low- to middle-income countries. We hypothesized that ULTV without extracorporeal circulation is a credible option to reduce COVID-19-related ARDS mortality and duration of mechanical ventilation. METHODS: The VT4COVID study is a randomized, multi-centric prospective open-labeled, controlled superiority trial. Adult patients admitted in the intensive care unit with COVID-19-related mild to severe ARDS defined by a PaO2/FiO2 ratio ≤ 150 mmHg under invasive mechanical ventilation for less than 48 h, and consent to participate to the study will be eligible. Patients will be randomized into two balanced parallels groups, at a 1:1 ratio. The control group will be ventilated with protective ventilation settings (tidal volume 6 mL kg-1 PBW), and the intervention group will be ventilated with ULTV (tidal volume 4 mL kg-1 PBW). The primary outcome is a composite score based on 90-day all-cause mortality as a prioritized criterion and the number of ventilator-free days at day 60 after inclusion. The randomization list will be stratified by site of recruitment and generated using random blocks of sizes 4 and 6. Data will be analyzed using intention-to-treat principles. DISCUSSION: The purpose of this manuscript is to provide primary publication of study protocol to prevent selective reporting of outcomes, data-driven analysis, and to increase transparency. Enrollment of patients in the study is ongoing. TRIAL REGISTRATION: ClinicalTrials.gov NCT04349618 . Registered on April 16, 2020.

The eSpiro Ventilator: An Open-Source Response to a Worldwide Pandemic.

OBJECTIVE: To address the issue of ventilator shortages, our group (eSpiro Network) developed a freely replicable, open-source hardware ventilator. DESIGN: We performed a bench study. SETTING: Dedicated research room as part of an ICU affiliated to a university hospital. SUBJECTS: We set the lung model with three conditions of resistance and linear compliance for mimicking different respiratory mechanics of representative intensive care unit (ICU) patients. INTERVENTIONS: The performance of the device was tested using the ASL5000 lung model. MEASUREMENTS AND MAIN RESULTS: Twenty-seven conditions were tested. All the measurements fell within the ±10% limits for the tidal volume (VT). The volume error was influenced by the mechanical condition (p = 5.9 × 10-15) and the PEEP level (P = 1.1 × 10-12) but the clinical significance of this finding is likely meaningless (maximum -34 mL in the error). The PEEP error was not influenced by the mechanical condition (p = 0.25). Our experimental results demonstrate that the eSpiro ventilator is reliable to deliver VT and PEEP accurately in various respiratory mechanics conditions. CONCLUSIONS: We report a low-cost, easy-to-build ventilator, which is reliable to deliver VT and PEEP in passive invasive mechanical ventilation.