Respiratory failure & ventilation
Early changes of lung mechanics after positive end-expiratory pressure reduction in acute respiratory distress syndrome: a four-dimensional computed tomography study
Authors' conclusion
At 3-5 minutes after a PEEP step-down from 15 to 5 cmH2O, 4D-CT showed large EELV loss, substantial alveolar derecruitment, and reduced over-inflation, while tidal recruitment slightly increased and remained low.
Study context
- Population
- Patients with stabilized acute respiratory distress syndrome (ARDS) (77.5% with PaO2/FIO2 ≥150, median normalized respiratory system compliance 0.78 mL/cmH2O/kg) on lung-protective volume-controlled ventilationcrossover, every patient at both positive end-expiratory pressure (PEEP) levels
- Participants
- 40 patients
- Comparison
- PEEP 15 vs 5 cmH2O
- Outcome
- Tidal recruitment and over-inflation on 4D-CT
- Follow-up
- 3-5 minutes
Methodological detailsprospective, single-centre
- Prospective
- Single-centre
Main finding
As reported in the abstract
Tidal recruitment (% of expiratory tissue weight), PEEP 15 → 5 cmH2O, P < .001
1.15% to 1.84%
End-inspiratory over-inflation (% of end-inspiratory lung volume), PEEP 15 → 5 cmH2O, P < .001
11.9% to 5.2%
Tidal over-inflation (% of tidal volume), PEEP 15 → 5 cmH2O, P < .001
42.5% to 18.3%
Further findings
End-expiratory lung volume (EELV) change after PEEP step-down · 3-5 min
- EELV substantially decreased
- median −787 mL (95% CI −952 to −743 mL, P < .001)
- Volume loss exceeded passive elastic prediction, indicating substantial alveolar derecruitment
Recruitment-to-inflation ratio as modifier of tidal recruitment response (exploratory)
- Recruitment-to-inflation ratio did not modify the tidal recruitment response
- Exploratory analyses
Original publication
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