High peak PaO2 values associated with adverse outcome in patients treated with noninvasive ventilation for acute cardiogenic pulmonary edema and pneumonia.

BACKGROUND

Noninvasive ventilation (NIV) has a sigificant impact on mortality in acute respiratory failure (ARF). Predictive parameters for mortality are of high interest.

METHODS

We retrospectively analyzed 3759 blood gas analysis and clinical parameters of 475 patients presenting with ARF based on acute cardiogenic pulmonary edema and/or pneumonia. The influence of peak arterial oxygen partial pressure levels (PaO2) with respect to its predictive value for in-hopital and long-term mortality was investigated.

RESULTS

Overall intra-hospital mortality was 24%. Peak PaO2 levels in kPa were significantly higher in non-survivors (20.01±10.11) compared to survivors (15.65±6.79, P<0.001). A univariate Cox proportional-hazards analysis for long-term mortality revealed associations with maximum PaO2 levels (overall cohort: HR= 1.02; 95% CI: 1.007-1.03; P=0.003; CPE: HR= 1.02; 95% CI: 0.99-1.04, P=0.05, pneumonia: HR= 1.02; 95% CI: 1-1.4, P=0.02). A PaO2 cut-off value of 13 kiloPascal (kPa) was calculated by means of Youden Index and remained true even after correction for APACHE 2 Score (HR= 1.50; 95% CI: 1.00-2.25; P=0.05) and for PaCO2 (HR= 1.63; 95% CI: 1.14-2.33; P=0.01).

CONCLUSIONS

Peak PaO2 levels were associated with worse in-hopital and long-term mortality in patients treated with NIV due to ARF. These findings may indicate that application of high oxygen may be detrimental in such patients.