Prognostic Value of Plateau Pressure Below 30 cm H₂O in Septic Patients With Acute Respiratory Failure

BACKGROUND: Ventilation with low tidal volume is recommended for patients with acute lung injury. Current guidelines suggest limiting plateau pressure (P_plat) to < 30 cm H₂O for septic patients needing mechanical ventilation. The aim of this study was to determine whether P_plat within the first 24 h of ICU admission is predictive of outcome and whether P_plat < 30 cm H₂O is associated with lower mortality rates.

METHODS: This study was a retrospective analysis of prospectively acquired clinical data from an ICU of a tertiary referral hospital in central Taiwan. Subjects were included if they were admitted due to sepsis and respiratory failure requiring mechanical ventilation from April 2008 to November 2009.

RESULTS: There were 220 subjects (188 males, 32 females) with a median age of 76 y and a mean Acute Physiology and Chronic Health Evaluation II score of 25.0 ± 6.5. Pneumonia was the major cause of sepsis (85.5%). The hospital mortality rate was 39.1%. P_plat was higher throughout the first 24 h of ICU admission in nonsurvivors. Higher P_plat was associated with higher mortality rates regardless of acute lung injury. In multivariate regression analysis, P_plat > 25 cm H₂O at 24 h after admission was an independent risk factor for mortality (adjusted odds ratio of 2.33, 95% CI 1.10 – 4.91, P = .03 for hospital mortality).

CONCLUSIONS: P_plat within the first 24 h of ICU admission is predictive of outcome, with lower P_plat associated with lower mortality rates. There is no safety margin for P_plat. Limiting P_plat should be considered even at < 30 cm H₂O in septic patients with acute respiratory failure.