Predictors of failed noninvasive positive pressure ventilation in patients with type II respiratory failure.

Objective To investigate the predictors of failed noninvasive positive pressure ventilation(NPPV) in patients with type Ⅱ respiratory failure.Methods The clinical data of 89 patients with type Ⅱ respiratory failure on NPPV in respiratory intensive care unit(RICU) of Beijing Chao-Yang Hospital from January 2004 to December 2009 were collected prospectively.Baseline characteristics,change of vital signs,arterial blood gas analysis before,at 2 h and 24 h after NPPV,and adverse effects were compared between success group(n=73) and failure group of NPPV(n=16).The relevant factors associated with NPPV failure were identified.Results Compared with success group,failure group had significantly higher total white blood cell counts,ratio of neutrophil,and lower levels of hemoglobin,albumin and prealbumin(P0.05).Success group had significant improvements in pH,PaCO2 and HR at the 2 and 24 hours after application of NPPV(P0.05),while failure group did not show any changes in pH and HR(P0.05) but a significant improvement in PaCO2 at 24 hours after application of NPPV(P0.05) with smaller amplitude.Exacerbation of respiratory failure due to difficult expectoration was the major cause of NPPV failure,which led to endotracheal intubation in 11 patients of failure group.Multivariate analysis identified ratio of neutrophil≥0.9 prior to NPPV(OR=9.86,95%CI 1.28～76.02,P=0.028),albumin28 g/L prior to NPPV(OR=11.30,95%CI 11.42～90.08,P=0.022) and difficult expectoration(OR=213.62,95%CI 11.93～3826.03,P=0.000) as independent factors associated with failure of NPPV.Conclusion In type Ⅱ respiratory failure,NPPV could be the first-line respiratory support in selected populations.In cases with severe pulmonary infection,difficult expectoration,or poor nutritional status,the risk of failed NPPV can be higher.In addition,NPPV are likely to be unsuccessful in patients with no or little improvements in pH,PaCO2 and hemodynamics after short duration of NPPV,or in patients with lower hemoglobin level.