Tolerance and Physiologic Effects of Nocturnal Mask Pressure Support vs Proportional Assist Ventilation in Chronic Ventilatory Failure

Abstract

To compare the tolerance and physiologic effects of a 5-night treatment with either nasal proportional assist ventilation (PAV) or pressure support ventilation (PSV) in patients with chronic ventilatory failure. Cross-over, randomized, controlled study. Rehabilitation units of pneumology department. Four patients with COPD and 10 patients with restrictive thoracic diseases with chronic hypercapnia (median baseline Paco(2), 55.1 mm Hg) were studied. In a cross-over study, nasal PAV and PSV set at the patient's comfort were randomly applied during 5 consecutive nights (with a 2-night washout period). Continuous nocturnal pulse oximetric saturation (Spo(2)) and arterial blood gas results at wake-up were evaluated at baseline during spontaneous breathing and on the fifth day of ventilatory support. Dyspnea, sleep quality, adaptation, and comfort at inspiration and expiration by visual analog scale (VAS) were evaluated every day as well as a side effects score. On the fifth day, there were no significant differences in daytime Paco(2) (median PAV, 53.3 mm Hg; median PSV, 50.2; p = 0.168). Mean nocturnal Spo(2) improved significantly with both PAV and PSV without any significant differences between modes (baseline median, 92%; PAV median, 94.5%; PSV median, 95%). The percentage of the study night spent < 90% Spo(2) (T90) was slightly but significantly higher with PAV than with PSV (median PAV T90, 4%; median PSV T90, 2%; p = 0.049). The VAS symptom score was similar at day 5 between modes; however, nasal and oral dryness were lower (p = 0.05) and alarm noise was higher (p = 0.037) with PAV. After 5 days of treatment, both modes had similar tolerance, and were equally effective in reducing daytime hypercapnia and improving nocturnal saturation and symptoms. However, PAV induced less nasal and oral dryness but was associated with higher alarm noise.