Respiratory variable predictors for intensive care mortality

Introduction

Nowadays it is not clear whether the level of hypoxemia is related to the outcome. It has been shown that the pulmonary dead space fraction is an independent risk factor for death in the early phase of acute respiratory distress syndrome [1].

Objective

We aimed to study possible respiratory predictors for mortality in mechanically ventilated patients.

Materials and methods

Consecutive patients invasively mechanically ventilated for more than 48 hours were enrolled. At ICU admission blood gas exchange and the ventilatory setting were recorded.

Results

Sixty-eight patients (45 males, mean age 59.6 ± 15.5 years, weight 71.6 ± 14.1 kg) were enrolled at one ICU from October 2004 to October 2005. Thirty-seven patients presented acute lung injury or acute respiratory distress syndrome during their intensive care stay.

The overall intensive care mortality was 23% (16 patients). The blood gas analysis showed a mean PaO₂/FiO₂ ratio of 207 ± 120 mmHg, PaCO₂ of 37 ± 10 mmHg and pH of 7.34 ± 0.13 with the following ventilatory setting: PEEP 8.1 ± 4.6 cmH₂O, respiratory rate 17.8 ± 5.2 bpm, tidal volume 662 ± 145 ml and minute ventilation 9.1 ± 2.0 l/min. Among the respiratory variables considered only the PaCO₂ was associated with an increased intensive care mortality (OR 1.08, 95% confidence interval 1.021–1.152).

Conclusion

The increase in PaCO₂, reflecting a higher degree of pulmonary impairment, was associated with intensive care mortality.