Objective: Treatment with noninvasive mechanical
ventilation (NMV) alleviates hypoventilation and improves gas exchange
in patients with chronic respiratory failure (CRF) due to thoracic
restriction. However, little is known about the effects of NMV on
respiratory and peripheral muscle endurance.
Prospective case-control study.
Subjects: Ten patients
in clinically stable condition (age, 53.5 ± 8.2 years[
mean ± SD]) with mild-to-moderate CRF due to thoracic
restriction (Pco2 between 45 mm Hg and 55 mm
Hg) were treated with NMV during the night for 3 months. Ten matched
patients (age, 52.2 ± 9.5 years) receiving 3 months of normal care
without NMV served as a control group.
measurements: After a 3-day period of familiarization with the
endurance tests, all patients performed a baseline preintervention
inspiratory threshold loading test, cycle ergometer test, and shuttle
walking test on the same day. The endurance tests were then repeated
following the 3-month intervention period.
NMV was used on average for 7.1 ± 0.9 h/d during the 3-month period.
There was a significant improvement in endurance time (p < 0.0001)
in all three endurance tests in the NMV group compared with the control
group. In the NMV group, endurance time increased by 278 ± 269%
during the inspiratory threshold loading test, by 176 ± 159% during
the cycle ergometer test, and by 32 ± 22% during the shuttle
walking test. Significant improvements (p < 0.01) in both
Po2 and Pco2 were also
observed in the NMV group but not in the control group.
Conclusions: Three months of treatment with NMV increases
both respiratory and peripheral muscle endurance in patients with CRF
due to thoracic restriction.