Do ventilatory parameters influence outcome in patients with severe acute respiratory infection? Secondary analysis of an international, multicentre14-day inception cohort study

Abstract

Purpose: To investigate the possible association between ventilatory settings on the first day of invasive mechanical ventilation (IMV) and mortality in patients admitted to the intensive care unit (ICU) with severe acute respiratory infection (SARI).

Materials and methods: In this pre-planned sub-study of a prospective, multicentre observational study, 441 patients with SARI who received controlled IMV during the ICU stay were included in the analysis.

Results: ICU and hospital mortality rates were 23.1 and 28.1%, respectively. In multivariable analysis, tidal volume and respiratory rate on the first day of IMV were not associated with an increased risk of death; however, higher driving pressure (DP: odds ratio (OR) 1.05; 95% confidence interval (CI): 1.01-1.1, p = 0.011), plateau pressure (Pplat) (OR 1.08; 95% CI: 1.04-1.13, p < 0.001) and positive end-expiratory pressure (PEEP) (OR 1.13; 95% CI: 1.03-1.24, p = 0.006) were independently associated with in-hospital mortality. In subgroup analysis, in hypoxemic patients and in patients with acute respiratory distress syndrome (ARDS), higher DP, Pplat, and PEEP were associated with increased risk of in-hospital death.

Conclusions: In patients with SARI receiving IMV, higher DP, Pplat and PEEP, and not tidal volume, were associated with a higher risk of in-hospital death, especially in those with hypoxemia or ARDS.

Keywords: ARDS; Airway pressures; Mechanical ventilation; PEEP; Plateau pressure; Pneumonia.

Fig. 1

Adjusted odds ratio of in-hospital death per 1 cmH₂O increase in driving pressure (DP) within subgroups of patients classified according to the median value of plateau pressure (Pplat), positive end-expiratory pressure (PEEP), tidal volume, PaO2/FiO2, and the presence or absence of acute respiratory distress syndrome (ARDS) on the first day of mechanical ventilation. Adjustment was made for simplified acute physiology score (SAPS II) score, age, and the degree of hypoxemia as assessed by the PaO₂/FiO₂ ratio.

Fig. 2

Adjusted odds ratio of in-hospital death per 1 cmH₂O increase in plateau pressure within subgroups of patients classified according to the median value of driving pressure, positive end-expiratory pressure (PEEP), tidal volume, PaO2/FiO2, and the presence or absence of acute respiratory distress syndrome (ARDS) on the first day of mechanical ventilation. Adjustment was made for simplified acute physiology score (SAPS II) score, age, and the degree of hypoxia as assessed by the PaO₂/FiO₂ ratio.

Fig. 3

Adjusted odds ratio of in-hospital death per 1 cmH₂O increase in positive end-expiratory pressure (PEEP) within subgroups of patients classified according to the median value of driving pressure, plateau pressure (Pplat), tidal volume, PaO₂/FiO₂, and the presence or absence of acute respiratory distress syndrome (ARDS) on the first day of mechanical ventilation. Adjustment was made for simplified acute physiology score (SAPS II) score, age, and the degree of hypoxia as assessed by the PaO₂/FiO₂ ratio.