Objectives: To determine the effects of long-term nocturnal intermittent positive-pressure ventilation (NIPPV) on symptoms, pulmonary function test results, sleep, and respiratory muscle performance in patients with ventilatory insufficiency due to severe kyphoscoliosis.
Design: A prospective study in which 16 severe kyphoscoliotic patients were treated with NIPPV delivered by volume-cycled and pressure-cycled ventilators, over a period of 36 months.
Interventions and measurements: At baseline, pulmonary function tests, blood gas measurements, polysomnography, and respiratory muscle strength (measured by noninvasive indexes) were obtained. Symptoms and the number of hospitalizations in the previous 6 months also were recorded. Patients then began using a ventilator for > 1 to 2 days, in order to select the type of ventilator and the appropriate interface. Patients returned for evaluation (in outpatient setting) every 6 months for a follow-up period of 3 years. At 6 months, polysomnography was repeated, and by the third year clinical and functional parameters had been reassessed.
Results: All symptoms improved significantly with NIPPV therapy, when compared with the baseline values. The mean (± SD) Pao2 and FVC values increased at 36 months compared with baseline values (62.6 ± 7.1 vs 67.8 ± 8.8 mm Hg, respectively; and 37.9 ± 7.2% vs 47.5 ± 11.9%, respectively; p < 0.05 for both). There were significant improvements in mean maximal inspiratory pressure (55.8 ± 17.4 to 78.5 ± 17.5 cm H2O), maximal expiratory pressure (53.8 ± 17.7 to 72.3 ± 11.0 cm H2O), mouth pressure (0.28 ± 0.08 to 0.22 ± 0.02 cmH2O), and pressure-time index (0.18 ± 0.05 to 0.11 ± 0.02; p < 0.05 for all comparisons). There were no significant differences in breathing pattern and ventilatory drive. After 6 months, nocturnal oxyhemoglobin saturation improved, however, there was no significant change in sleep architecture. All patients subjectively perceived a better quality of life after beginning ventilation, which persisted over the course of the study.
Conclusions: Long-term NIPPV therapy improves daytime blood gas levels, respiratory muscle performance, and hypoventilation-based symptoms in patients with severe kyphoscoliosis.