Dataset Information

Dynamic hyperinflation and intrinsic positive end-expiratory pressure in ARDS patients.

ABSTRACT:

Background

In ARDS patients, changes in respiratory mechanical properties and ventilatory settings can cause incomplete lung deflation at end-expiration. Both can promote dynamic hyperinflation and intrinsic positive end-expiratory pressure (PEEP). The aim of this study was to investigate, in a large population of ARDS patients, the presence of intrinsic PEEP, possible associated factors (patients' characteristics and ventilator settings), and the effects of two different external PEEP levels on the intrinsic PEEP.

Methods

We made a secondary analysis of published data. Patients were ventilated with a tidal volume of 6-8 mL/kg of predicted body weight, sedated, and paralyzed. After a recruitment maneuver, a PEEP trial was run at 5 and 15 cmH₂O, and partitioned mechanics measurements were collected after 20 min of stabilization. Lung computed tomography scans were taken at 5 and 45 cmH₂O. Patients were classified into two groups according to whether or not they had intrinsic PEEP at the end of an expiratory pause.

Results

We enrolled 217 sedated, paralyzed patients: 87 (40%) had intrinsic PEEP with a median of 1.1 [1.0-2.3] cmH₂O at 5 cmH₂O of PEEP. The intrinsic PEEP significantly decreased with higher PEEP (1.1 [1.0-2.3] vs 0.6 [0.0-1.0] cmH₂O; p < 0.001). The applied tidal volume was significantly lower (480 [430-540] vs 520 [445-600] mL at 5 cmH₂O of PEEP; 480 [430-540] vs 510 [430-590] mL at 15 cmH₂O) in patients with intrinsic PEEP, while the respiratory rate was significantly higher (18 [15-20] vs 15 [13-19] bpm at 5 cmH₂O of PEEP; 18 [15-20] vs 15 [13-19] bpm at 15 cmH₂O). At both PEEP levels, the total airway resistance and compliance of the respiratory system were not different in patients with and without intrinsic PEEP. The total lung gas volume and lung recruitability were also not different between patients with and without intrinsic PEEP (respectively 961 [701-1535] vs 973 [659-1433] mL and 15 [0-32] % vs 22 [0-36] %).

Conclusions

In sedated, paralyzed ARDS patients without a known obstructive disease, the amount of intrinsic PEEP during lung-protective ventilation is negligible and does not influence respiratory mechanical properties.

SUBMITTER: Coppola S

PROVIDER: S-EPMC6880369 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Publications

Dynamic hyperinflation and intrinsic positive end-expiratory pressure in ARDS patients.

Coppola Silvia S Caccioppola Alessio A Froio Sara S Ferrari Erica E Gotti Miriam M Formenti Paolo P Chiumello Davide D

Critical care (London, England) 20191127 1

<h4>Background</h4>In ARDS patients, changes in respiratory mechanical properties and ventilatory settings can cause incomplete lung deflation at end-expiration. Both can promote dynamic hyperinflation and intrinsic positive end-expiratory pressure (PEEP). The aim of this study was to investigate, in a large population of ARDS patients, the presence of intrinsic PEEP, possible associated factors (patients' characteristics and ventilator settings), and the effects of two different external PEEP l ...[more]

PMID: 31775830

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Project description:ImportanceIt is uncertain whether invasive ventilation can use lower positive end-expiratory pressure (PEEP) in critically ill patients without acute respiratory distress syndrome (ARDS).ObjectiveTo determine whether a lower PEEP strategy is noninferior to a higher PEEP strategy regarding duration of mechanical ventilation at 28 days.Design, setting, and participantsNoninferiority randomized clinical trial conducted from October 26, 2017, through December 17, 2019, in 8 intensive care units (ICUs) in the Netherlands among 980 patients without ARDS expected not to be extubated within 24 hours after start of ventilation. Final follow-up was conducted in March 2020.InterventionsParticipants were randomized to receive invasive ventilation using either lower PEEP, consisting of the lowest PEEP level between 0 and 5 cm H2O (n = 476), or higher PEEP, consisting of a PEEP level of 8 cm H2O (n = 493).Main outcomes and measuresThe primary outcome was the number of ventilator-free days at day 28, with a noninferiority margin for the difference in ventilator-free days at day 28 of -10%. Secondary outcomes included ICU and hospital lengths of stay; ICU, hospital, and 28- and 90-day mortality; development of ARDS, pneumonia, pneumothorax, severe atelectasis, severe hypoxemia, or need for rescue therapies for hypoxemia; and days with use of vasopressors or sedation.ResultsAmong 980 patients who were randomized, 969 (99%) completed the trial (median age, 66 [interquartile range {IQR}, 56-74] years; 246 [36%] women). At day 28, 476 patients in the lower PEEP group had a median of 18 ventilator-free days (IQR, 0-27 days) and 493 patients in the higher PEEP group had a median of 17 ventilator-free days (IQR, 0-27 days) (mean ratio, 1.04; 95% CI, 0.95-∞; P = .007 for noninferiority), and the lower boundary of the 95% CI was within the noninferiority margin. Occurrence of severe hypoxemia was 20.6% vs 17.6% (risk ratio, 1.17; 95% CI, 0.90-1.51; P = .99) and need for rescue strategy was 19.7% vs 14.6% (risk ratio, 1.35; 95% CI, 1.02-1.79; adjusted P = .54) in patients in the lower and higher PEEP groups, respectively. Mortality at 28 days was 38.4% vs 42.0% (hazard ratio, 0.89; 95% CI, 0.73-1.09; P = .99) in patients in the lower and higher PEEP groups, respectively. There were no statistically significant differences in other secondary outcomes.Conclusions and relevanceAmong patients in the ICU without ARDS who were expected not to be extubated within 24 hours, a lower PEEP strategy was noninferior to a higher PEEP strategy with regard to the number of ventilator-free days at day 28. These findings support the use of lower PEEP in patients without ARDS.Trial registrationClinicalTrials.gov Identifier: NCT03167580.

Dataset Information

Dynamic hyperinflation and intrinsic positive end-expiratory pressure in ARDS patients.

Background

Methods

Results

Conclusions

Publications

Dynamic hyperinflation and intrinsic positive end-expiratory pressure in ARDS patients.

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