Positive end-expiratory pressure-induced recruited lung volume measured by volume-pressure curves in acute respiratory distress syndrome: a physiologic systematic review and meta-analysis

Abstract

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 (V rec increase versus no increase) using the VP curve in order to assess the relation between V rec 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 V rec by the GRADE approach. Recruiters were defined as patients with a V rec > 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, V rec was not associated with mortality but Simplified Acute Physiology Score II and driving pressure at PEEP of 5 cmH 2 O were. Conclusion: After a PEEP increment, most patients are recruiters. V rec 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 cmH 2 O was

Differential Prognostic Analysis of Higher and Lower PEEP in ARDS Patients: Systematic Review and Meta-Analysis

“…In this way, early alveolar closure can be avoided, and some alveoli that lose ventilation function due to exudation, atelectasis, and other reasons will expand so that the reduced functional residual volume will increase, and the purpose of improving blood oxygen can be achieved [ 10 ]. PEEP is similar to intermittent positive pressure respiration, but because of its longer duration of action, it has a wider range of effects on the respiratory and circulatory systems [ 11 ]. PEEP is the external pressure applied to the airway by the ventilator at the end of the patient's expiratory breath during mechanical ventilation.…”

Lung Recruitability Evaluated by Recruitment-to-Inflation Ratio and Lung Ultrasound in COVID-19 Acute Respiratory Distress Syndrome

“…A substantial proportion of patients with coronavirus disease (COVID-19) admitted to the ICU require invasive mechanical ventilation for acute respiratory distress syndrome (ARDS), which is still associated with a high mortality rate ( 1 ). Applying the optimal positive end-expiratory pressure (PEEP) to ensure lung recruitment while limiting lung hyperinflation remains challenging in ARDS ( 2 , 3 ). Yet, there are a few simple tools that might help personalize the level of PEEP in those patients at the bedside.…”

“…Yet, there are a few simple tools that might help personalize the level of PEEP in those patients at the bedside. Among them, the lung ultrasound (LUS) aeration score and the recruitment-to-inflation (R/I) ratio have the potential to identify patients who are more likely to benefit from PEEP ( 2 ). Previous studies indeed suggested that LUS could assess spatial distribution of PEEP-induced lung recruitment but does not reliably detect hyperinflation ( 4 , 5 ).…”

Is severe COVID-19 pneumonia a typical or atypical form of ARDS? And does it matter?

“…It is widely appreciated that ARDS is a heterogeneous disorder and that many patients with ARDS may have little or no potential for lung recruitment [16][17][18]. Higher PEEP may well be harmful in such patients whether or not they have COVID-19 [19].…”