Analysis on relevant factors of non-invasive positive pressure ventilation failure in the patients with acute respiratory failure

Objective To study the factors associated with development of non-invasive positive pressure ventilation(NPPV)failure in patients with acute respiratory failure(ARF),to research the time that NPPV should be replaced by invasive ventilation when NPPV failure occurred.Methods Seventy-four patients with ARF resulted from variant diseases were investigated and divided into NPPV failure group and NPPV success group.Physiological and clinical parameters were studied comparatively between two groups.Factors associated with failure of NPPV were analysed.Results Failure rate of NPPV was 29.7%(22/74).Respiratory rate (RR),heart rate (HR)and PaCO_2 were higher and pH was lower significantly in patients in NPPV failure group on admission,compared with NPPV success group( P 0.05).Logistic regression analysis showed that the occurrence of NPPV failure was significantly associated with RR30 breath/min,HR130 beat/min,PaCO_260 mmHg and pH7.3.In NPPY success group,there was obvious improvement of PaO_2 at one and six hours after NPPV therapy compared with baseline ( P 0.05).In NPPV failure group,there was not statistical difference in measured results of arterial blood gases between after and before NPPV therapy.Conclusions NPPV failure in patients with ARF was influenced by markedly abnormal RR,HR,PaCO_2 and pH.Improvement of arterial blood gases within 1～6 hours after NPPV was index for predicting success of treatment.NPPV should be replaced promptly by tracheal intubation and invasive ventilation when failure occurs.