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Tidal expiratory flow limitation (EFL), which may herald airway closure (AC), is a mechanism of loss of aeration in ARDS. In this prospective, short-term, two-center study, we measured static and dynamic chest wall (Est,cw and Edyn,cw) and lung (Est,L and Edyn,L) elastance with esophageal pressure, EFL, and AC at 5 cmH(2)O positive end-expiratory pressure (PEEP) in intubated, sedated, and paralyzed ARDS patients. For EFL determination, we used the atmospheric method and a new device allowing comparison of tidal flow during expiration to PEEP and to atmosphere. AC was validated when airway opening pressure (AOP) assessed from volume-pressure curve was found greater than PEEP by at least 1 cmH(2)O. EFL was defined whenever flow did not increase between exhalation to PEEP and to atmosphere over all or part of expiration. Elastance values were expressed as percentage of normal predicted values (%N). Among the 25 patients included, eight had EFL (32%) and 13 AOP (52%). Between patients with and without EFL Edyn,cw [median (1st to 3rd quartiles)] was 70 (16-127) and 102 (70-142) %N (P = 0.32) and Edyn,L338 (332-763) and 224 (160-275) %N (P \textless 0.001). The corresponding values for Est,cw and Est,L were 70 (56-88) and 85 (64-103) %N (P = 0.35) and 248 (206-348) and 170 (144-195) (P = 0.02), respectively. Dynamic E(L) had an area receiver operating characteristic curve of 0.88 [95% confidence intervals 0.83-0.92] for EFL and 0.74[0.68-0.79] for AOP. Higher Edyn,L was accurate to predict EFL in ARDS patients; AC can occur independently of EFL, and both should be assessed concurrently in ARDS patients.NEW & NOTEWORTHY Expiratory flow limitation (EFL) and airway closure (AC) were observed in 32% and 52%, respectively, of 25 patients with ARDS investigated during mechanical ventilation in supine position with a positive end-expiratory pressure of 5 cmH(2)O. The performance of dynamic lung elastance to detect expiratory flow limitation was good and better than that to detect airway closure. The vast majority of patients with EFL also had AC; however, AC can occur in the absence of EFL.

Background Little is known on the association between local signs and intravascular catheter infections. This study aimed to evaluate the association between local signs at removal and catheter-related bloodstream infections (CRBSI), and which clinical conditions may predict CRBSIs if inflammation at insertion site is present. Methods We used individual data from four multicenter randomized controlled trials in intensive care units (ICUs) that evaluated various prevention strategies for arterial and central venous catheters. We used multivariate logistic regressions in order to evaluate the association between ≥ 1 local sign, redness, pain, non-purulent discharge and purulent discharge, and CRBSI. Moreover, we assessed the probability for each local sign to observe CRBSI in subgroups of clinically relevant conditions. Results A total of 6976 patients and 14,590 catheters (101,182 catheter-days) and 114 CRBSI from 25 ICUs with described local signs were included. More than one local sign, redness, pain, non-purulent discharge, and purulent discharge at removal were observed in 1938 (13.3%), 1633 (11.2%), 59 (0.4%), 251 (1.7%), and 102 (0.7%) episodes, respectively. After adjusting on confounders, ≥ 1 local sign, redness, non-purulent discharge, and purulent discharge were associated with CRBSI. The presence of ≥ 1 local sign increased the probability to observe CRBSI in the first 7 days of catheter maintenance (OR 6.30 vs. 2.61 [> 7 catheter-days], pheterogeneity = 0.02). Conclusions Local signs were significantly associated with CRBSI in the ICU. In the first 7 days of catheter maintenance, local signs increased the probability to observe CRBSI.

IntroductionIn intensive care unit (ICU), the decision of extubation is a critical time because mortality is particularly high in case of reintubation. To reduce that risk, guidelines recommend to systematically perform a spontaneous breathing trial (SBT) before extubation in order to mimic the postextubation physiological conditions. SBT is usually performed with a T-piece disconnecting the patient from the ventilator or with low levels of pressure-support ventilation (PSV). However, work of breathing is lower during PSV than during T-piece. Consequently, while PSV trial may hasten extubation, it may also increase the risk of reintubation. We hypothesise that, compared with T-piece, SBT performed using PSV may hasten extubation without increasing the risk of reintubation.Methods and analysisThis study is an investigator-initiated, multicentre randomised controlled trial comparing T-piece vs PSV for SBTs in patients at high risk of reintubation in ICUs. Nine hundred patients will be randomised with a 1:1 ratio in two groups according to the type of SBT. The primary outcome is the number of ventilator-free days at day 28, defined as the number of days alive and without invasive mechanical ventilation between the initial SBT (day 1) and day 28. Secondary outcomes include the number of days between the initial SBT and the first extubation attempt, weaning difficulty, the number of patients extubated after the initial SBT and not reintubated within the following 72 hours, the number of patients extubated within the 7 days following the initial SBT, the number of patients reintubated within the 7 days following extubation, in-ICU length of stay and mortality in ICU, at day 28 and at day 90.Ethics and disseminationThe study has been approved by the central ethics committee ‘Ile de France V’ (2019-A02151-56) and patients will be included after informed consent. The results will be submitted for publication in peer-reviewed journals.Trial registration numberNCT04227639.

International audience; BACKGROUND:During preoxygenation, the lack of tight fit between the mask and the patient's face results in inward air leak preventing effective preoxygenation. We hypothesized that non-invasive positive-pressure ventilation and positive end-expiratory pressure (PEEP) could counteract inward air leak.METHODS:Healthy volunteers were randomly assigned to preoxygenated through spontaneous breathing without leak (SB), spontaneous breathing with a calibrated air leak (T-shaped piece between the mouth and the breathing system; SB-leak), or non-invasive positive inspiratory pressure ventilation (inspiratory support +6 cm H2O; PEEP +5 cm H2O) with calibrated leak (PPV-leak). The volunteers breathed through a mouthpiece connected to an anaesthesia ventilator. The expired oxygen fraction (FeO2) and air-leak flow (ml s-1) were measured. The primary end point was the proportion of volunteers with FeO2 >90% at 3 min. The secondary end points were FeO2 at 3 min, time to reach FeO2 of 90%, and the inspiratory air-leak flow.RESULTS:Twenty healthy volunteers were included. The proportion of volunteers with FeO2 >90% at 3 min was 0% in the SB-leak group, 95% in the SB group, and 100% in the PPV-leak group (P

Purpose Recruitment of lung volume is often cited as the reason for using positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS) patients. We performed a systematic review on PEEP-induced recruited lung volume measured from inspiratory volume-pressure (VP) curves in ARDS patients to assess the prevalence of patients with PEEP-induced recruited lung volume and the mortality in recruiters and non-recruiters. Methods We conducted a systematic search of PubMed to identify studies including ARDS patients in which the intervention of an increase in PEEP was accompanied by measurement of the recruited volume (Vrec increase versus no increase) using the VP curve in order to assess the relation between Vrec and mortality at ICU discharge. We first analysed the pooled data from the papers identified and then analysed individual patient level data received from the authors via personal contact. The risk of bias of the included papers was assessed using the quality in prognosis studies tool and the certainty of the evidence regarding the relationship of mortality to Vrec by the GRADE approach. Recruiters were defined as patients with a Vrec > 150 ml. A random effects model was used for the pooled data. Multivariable logistic regression analysis was used for individual patient data. Results We identified 16 papers with a total of 308 patients for the pooled data meta-analysis and 14 papers with a total of 384 patients for the individual data analysis. The quality of the articles was moderate. In the pooled data, the prevalence of recruiters was 74% and the mortality was not significantly different between recruiters and non-recruiters (relative risk 1.20 [95% confidence intervals 0.88–1.63]). The certainty of the evidence regarding this association was very low and publication bias evident. In the individual data, the prevalence of recruiters was 70%. In the multivariable logistic regression, Vrec was not associated with mortality but Simplified Acute Physiology Score II and driving pressure at PEEP of 5 cmH2O were. Conclusion After a PEEP increment, most patients are recruiters. Vrec was not associated with ICU mortality. The presence of similar findings in the individual patient level analysis and the driving pressure at PEEP of 5 cmH2O was associated with mortality as previously reported validate our findings. Publication bias and the lack of prospective studies suggest more research is required. Electronic supplementary material The online version of this article (10.1007/s00134-020-06226-9) contains supplementary material, which is available to authorized users.

BACKGROUND: Automatic tube compensation (ATC) unloads endotracheal tube (ETT) resistance. We conducted a bench assessment of ATC functionality in ICU ventilators to improve clinical management. METHODS: This study had 2 phases. First, we performed an international survey on the use of ATC in clinical practice, hypothesizing a rate of ATC use of 25%. Second, we tested 7 modern ICU ventilators in a lung model mimicking a normal subject (Normal), a subject with ARDS, and a subject with COPD. Inspiratory effort consisted of esophageal pressure over 30 consecutive breaths obtained in a real patient under weaning. A brand new 8-mm inner diameter ETT was attached to the lung model, and ATC was set at 100% compensation for the ETT. The 30 breaths were first run with ATC off and no ETT (ie, reference period), and then with ATC on and ETT (ie, active period). The primary end point was the difference in tidal volume (V(T)) between reference and active periods. We hypothesized that the V(T) difference should be equal to 0 in an ideally functioning ATC. V(T) difference was compared across ventilators and respiratory mechanics conditions using a linear mixed-effects model. RESULTS: The clinical use of ATC was 64% according to 644 individuals who responded to the international survey. The V(T) difference varied significantly across ventilators in all respiratory mechanics configurations. The divergence between V(T) difference and 0 was small but significant: the extreme median (interquartile range) values were -0.013 L (-0.019 to -0.002) in the COPD model and 0.056 L (0.051-0.06) in the Normal model. V(T) difference for all ventilators was 0.015 L (95% CI 0.013-0.018) in the ARDS model, which was significantly different from 0.021 L (95% CI 0.018-0.024) in the Normal model (P \textless .001) and 0.010 L (0.007-0.012) in the COPD model (P = .003). CONCLUSIONS: ATC is used more frequently in clinical practice than expected. In addition, V(T) delivery by ATC differed slightly though significantly between ventilators.

Background During spontaneous breathing trial, low-pressure support is thought to compensate for endotracheal tube resistance, but it actually should provide overassistance. Automatic tube compensation is an option available in the ventilator to compensate for flow-resistance of endotracheal tube. Its effects on patient effort have been poorly investigated. We aimed to compare the effects of low-pressure support and automatic tube compensation during spontaneous breathing trial on breathing power and lung ventilation distribution. Results We performed a randomized crossover study in 20 patients ready to wean. Each patient received both methods for 30 min separated by baseline ventilation: pressure support 0 cmH2O and automatic tube compensation 100% in one period and pressure support 7 cmH2O without automatic tube compensation in the other period, a 4 cmH2O positive end-expiratory pressure being applied in each. Same ventilator brand (Evita XL, Draeger, Germany) was used. Breathing power was assessed from Campbell diagram with esophageal pressure, airway pressure, flow and volume recorded by a data logger. Lung ventilation distribution was assessed by using electrical impedance tomography (Pulmovista, Draeger, Germany). During the last 2 min of low-pressure support and automatic compensation period breathing power and lung ventilation distribution were measured on each breath. Breathing power generated by the patient’s respiratory muscles was 7.2 (4.4–9.6) and 9.7 (5.7–21.9) J/min in low-pressure support and automatic tube compensation periods, respectively (P = 0.011). Lung ventilation distribution was not different between the two methods. Conclusions We found that ATC was associated with higher breathing power than low PS during SBT without altering the distribution of lung ventilation.