2001 - A REVIEW OF LONG-TERM NOCTURNAL NON-INVASIVE POSITIVE PRESSURE VENTILATION IN CHRONIC HYPERCARPNIC RESPIRATORY FAILURE
Dr. LEUNG Wah Shing, Department of Medicine, United Christian Hospital
ABSTRACT:
Chronic respiratory failure is an important cause of mortality and morbidity. The use of home non-invasive intermittent positive pressure ventilation (NIPPV) has been shown to be effective in restrictive ventilatory disorders. We reviewed the use of long-term home NIPPY in 23 patients in the United Christian Hospital from October 1997 to September 1999. This consisted of two groups, restrictive ventilatory disorder and chronic obstructive pulmonary disease (COPD).
In the restrictive ventilatory disorder group (n=17), the use of NIPPV was found to improve the nighttime gas exchange, dyspnoea sensation, exercise tolerance, Epworth Sleepiness Score, days of hospitalization, and quality of life in the restrictive ventilatory disorder group. Before NIPPV, patients spent 56.9(SEM=7.8)% of time with oxygen saturation (SaO2) > 90% and this improved to 90.6(SEM=5.8)% after NIPPY (95% CI, 18.0-49.3%, p<0.001l). Minimum SaO2 during the night improved from 58.6(SEM=3.8)% to 77.5(SEM=2A)% (95% CI, 13.8-24.0%, p< 0.001). Six minute walk distance improved from 308.0(SEM=21.8)m to 420.0(SEM=41.6)m(95% CI, 13.6-210.4m, p=0.029). Dyspnoea sensation by the visual analogue scale improved significantly from 4.2(SEM=0.7) to 2.7(SEM=0.5) (95% CI, 0.5-2.5, p=0.005). Days of hospitalization per year were reduced from 22.8(SEM=4.7) to 4.6(SEM=2.9) (95% CI, 5.9-30A, p=0.006). Epworth Sleepiness Score (ESS) improved from 12.7(SEM=1.1) to 5.6(SEM=0.7) (95% CI, 4.6-9.6, p<0.001).There were significant improvements in the short form of Chinese version of World Health Organization Quality of Life measures (WHOQOL-BREF-HK) score in physical domain from 10.3(SEM=0.3) to 13.4(SEM=0.7) (95% CI, 1.6-4.7, p=0.001) and in psychological domain from 11.3(SEM=0.5) to 13.3(SEM=0.5) (95% CI, 1.0-2.9, p=0.00l) respectively. Trend of improvement was observed in the daytime arterial blood gas, though it was not statistically significant.
Improvement in the physical domain of WHOQOL-BREF-HK correlated independently with improvement in PaO2 (p=0.047) and 6-minute walk distance (p=0.008); adjusted R square was 0.556. Improvement in the psychological domain correlated independently with improvement in PaO2 (p=0.008) and Epworth Sleepiness Score (p=0.009), adjusted R square was 0.503.In the COPD group (n=4), there was no significant difference in the outcome measure, which might be due to small patient number. However, trend of improvement was observed in daytime ABG, nighttime gas exchange and days of hospitalization. Sixty-eight percent of patients with restrictive ventilatory disorder were started on NIPPY only after acute respiratory failure, and this indicated that the consideration for long-term ventilatory support was probably delayed. Most of the problems were related to mask discomfort.
