Optimal time of the use of noninvasive positive pressure ventilation in the patients with II respiratory failure and chronic obstructive pulmonary disease

Objective To evaluate the optimal time of the use of noninvasive positive pressure ventilation(NIPPV) in the patients with Ⅱ respiratory failure and chronic obstructive pulmonary disease(COPD).Methods 120 patients were divided at random NIPPV group and conventional therapy group(control group).Clinical symptoms,arterial blood gases,pulmonary functions and clinical outcomes were measured before and after treatment.Patients were again divided into mild,moderate and severe group to determine the optimal time of NIPPV.Results Heart rate,respiratory rate,dyspnea score,scale for accessory muscle use and arterial blood gases were improved rapidly at 2 h after treatment in NIPPV group(P0.05).The use of NIPPV reduced the duration of hospital(from 20.6±28.9 d to 12.4±9.9 d,P0.05),the rate of intubation(from 26.7% to 11.7%),the hospital mortality(from 13.3% to 3.3%,P0.05).NIPPV was succeeded in mild and moderate group but failed in severe group.Conclusion NIPPV should be used earlier in the patients with Ⅱ respiratory failure and COPD.The optimal time was 50 mmHgPaCO_2≤90 mmHg,40 mmHg≤PaO_260 mmHg.