Chest
Volume 116, Issue 3, September 1999, Pages 667-675
Journal home page for Chest

Clinical Investigations
Sleep/CPAP
Efficacy and Compliance With Noninvasive Positive Pressure Ventilation in Patients With Chronic Respiratory Failure

https://doi.org/10.1378/chest.116.3.667Get rights and content

Study objectives

Previous studies have shown the acute effects of noninvasive positive pressure ventilation (NPPV) in chronic respiratory failure; however, information on the chronic effects of NPPV is limited. We examined the acute and chronic effects of NPPV on gas exchange, functional status, and respiratory mechanics in patients with chronic respiratory failure related 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 COPD and 20 with restrictive ventilatory disorders).

Interventions and measurements

All patients were admitted to a noninvasive respiratory care unit for 20 ± 3 days for inpatient evaluation consisting of medical treatment, rehabilitation, and NPPV evaluation and instruction. NPPV was titrated via a ventilatory support system (BiPAP; Respironics Inc; Monroeville, PA) or a portable volume ventilator (PLV 102; Lifecare, Inc; Boulder, CO) to achieve a ≥ 20% increase in baseline 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 was 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 with COPD, 1 with restrictive disorder) used a portable volume ventilator and 34 patients used BiPAP (15 with COPD, 19 with restrictive disorders). At discharge, compared with at admission, daytime Pao2/fraction of inspired oxygen (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 increased (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 ± 13; p = 0.05), Paco2 (52 ± 2 vs 67 ± 3 mm Hg; p = 0.0001), and functional score (5.66 ± 0.41 vs 2.7 ± 0.3 AUs; p < 0.001) were maintained compared with admission values. FVC, FEV1, and maximum inspired and expired mouth pressures were unchanged before and after long-term NPPV. Ten patients (7 with COPD, 3 with restrictive disorders) discontinued NPPV at 6 months, and 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 required adjustment in either the mask (36%) or ventilator source (36%) included 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 functional status in patients with chronic respiratory failure, but a significant number of patients do not tolerate NPPV on a chronic basis. Comprehensive follow-up is required to correct problems with NPPV and ensure optimal patient compliance.

Section snippets

Patient Selection

Forty consecutive patients were admitted to the Ventilator Rehabilitation Unit (VRU) at Temple University Hospital for evaluation and treatment of chronic respiratory failure. Prior to VRU admission and enrollment into the study, all patients were treated at least 48 h with maximally effective doses of inhaled bronchodilators (eg, β-agonist and anticholinergic agents), systemic and/or inhaled corticosteroids, supplemental oxygen and, on occasion, theophylline. Following maximization of medical

Patient Characteristics

Patient characteristics are shown in Table 2. An equal number of the 40 patients enrolled in the study had COPD or restrictive disorders as the primary process responsible for respiratory failure. Of the 20 patients with restrictive disorders, 5 had kyphoscoliosis, 6 had obesity hypoventilation syndrome, 6 had an underlying chronic neuromuscular disease, and 3 had fibrothorax. For the total group, the average age was 65 ± 9.7 years with a 3:1 female:male predominance. Sixteen of the 40 patients

Discussion

Our data show that in moderately ill patients with chronic respiratory failure, NPPV was associated with acute and chronic improvements in gas exchange and functional status. In contrast, chronic NPPV was not associated with an improvement in spirometry or respiratory muscle strength. Despite enrollment in a comprehensive program (with both inpatient and outpatient components), only 65% of patients continued to use NPPV on a chronic basis. Only half of the patients with severe COPD and

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Supported in part by grant No. 29-P-99401/3–01 from the Health Care Financing Administration.

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