Efficacy and compliance with noninvasive positive pressure ventilation in patients with chronic respiratory failure

Study objectives: Previous studies have shown the acute effects of noninvas ive positive pressure ventilation (NPPV) in chronic respiratory failure; ho wever, information on the chronic effects of NPPV is limited. We examined t he acute and chronic effects of NPPV on gas exchange, functional status, an d respiratory mechanics in patients with chronic respiratory failure relate d to restrictive ventilatory disorders or COPD. Design: Descriptive analysis of prospectively collected clinical data. Setting: Inpatient noninvasive respiratory care unit and outpatient clinic of university hospital. Patients: Forty patients with chronic respiratory failure (20 with severe C OPD and 20 with restrictive ventilatory disorders). Interventions and measure me nts: All patients were admitted to a noninvasi ve respiratory care unit for 20 +/- 3 days for inpatient evaluation consist ing of medical treatment, rehabilitation, and NPPV evaluation and instructi on. NPPV was titrated via a ventilatory support system (BiPAP; Respironics Inc; Monroeville, PA) or a pot-table volume ventilator (PLV 102; Lifecare, Inc; Boulder, CO) to achieve a greater than or equal to 20% increase in bas eline minute ventilation while monitoring gas exchange, expired volume, and clinical evidence of a decrease in the patient's work of breathing. Results: The patients' mean age (+/- SD) was 65 +/- 9.7 years, and there wa s a 3:1 female:male predominance. In the noninvasive respiratory care unit, 36 patients used NPPV for 7.31 +/- 0.26 h/night. Four patients (three with COPD, one with restrictive disorder) withdrew from the study during the 3- week inpatient stay because they could not tolerate NPPV. Six patients (5 w ith COPD, 1 with restrictive disorder) used a portable volume ventilator an d 34 patients used BiPAP (15 with COPD, 19 with restrictive disorders). At discharge, compared with at admission, daytime PaO2/fraction of inspired ox ygen (FIO2) increased (327 +/- 10 vs 283 +/- 13 mm Hg; p = 0.01), PaCO2 was reduced (52 +/- 2 vs 67 +/- 3 mm Hg; p = 0.0001), and functional score inc reased (4.76 +/- 1.16 vs 2.7 +/- 1.64 arbitrary units (AUs); p < 0.01). Six months after discharge, improvements in PaO2/FIO2 (317 +/- 10 vs 283 +/- 1 3; p = 0.05), PaCO2 (52 +/- 2 vs 67 +/- 3 mm Hg; p = 0.0001), and functiona l score (5.66 +/- 0.41 vs 2.7 +/- 0.3 AUs; p < 0.001) were maintained compa red with admission values, FVC, FEV1, and maximum inspired and expired mout h pressures were unchanged before and after long-term NPPV. Ten patients (7 with COPD, 3 with restrictive disorders) discontinued NPPV at 6 months, an d 3 progressed to tracheostomy. The remaining 26 patients continued to use NPPV at the 6-month follow-up. They claimed to use NPPV for 7.23 +/- 0.24 h /night, but logged metered use was 4.5 +/- 0.58 h/night. Problems that requ ired adjustment in either the mask (36%) or ventilator source (36%) include d mask leaks (43%), skin irritation (22%), rhinitis (13%), aerophagia (13%) , and discomfort from mask headgear (7%). Conclusion: NPPV acutely and chronically improves gas exchange and function al status in patients with chronic respiratory failure, but a significant n umber of patients do not tolerate NPPV on a chronic basis. Comprehensive fo llow-up is required to correct problems with NPPV and ensure optimal patien t compliance.