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.
Inpatient noninvasive respiratory care unit and outpatient clinic of
Patients: Forty patients with
chronic respiratory failure (20 with severe COPD and 20 with
restrictive ventilatory disorders).
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%).
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