NONINVASIVE POSITIVE PRESSURE VENTILATION AND NOT OXYGEN MAY PREVENT OVERT VENTILATORY FAILURE IN PATIENTS WITH CHEST-WALL DISEASES

Some patients with chest wall diseases (CWD) without respiratory failu re manifest important alterations in nocturnal gas exchange, as a prev ious stage to the future development of daytime respiratory failure, T he pur pose of this study was to evaluate the efficacy of nasal interm ittent positive pressure ventilation (NIPPV) during sleep in a group o f obese patients and in another group with restrictive thoracic diseas es (RTD), comparing the results with those obtained from conventional nocturnal oxygen therapy, From a total of 42 patients with CWD free of daytime respiratory failure, 27 (64%) were considered nocturnal oxyge n desaturators without sleep apnea and were included in the study, The study protocol was completed by 21 of these patients, After 2 weeks o f treatment, symptoms of dyspnea, morning headaches, and morning obnub ilation improved significantly (p<0.05) in both groups of patients aft er NIPPV but not with oxygen. Baseline daytime PaO2 was 68+/-7 mm Hg i n the obese group of patients and 73+/-11 mm Hg in the RTD group. It i mproved significantly with NIPPV to 73+/-5 mm Hg in obese patients (p< 0.05) and to 77+/-12 mm Hg in the RTD group (p<0.05) but did not chang e with oxygen (68+/-8 mm Hg in the obese group and 73+/-12 mm Hg in th e RTD group), Both treatments improved oxygen saturation during sleep, but oxygenation tends to be higher with oxygen than with NIPPV. Only NIPPV was able to normalize the baseline nocturnal alveolar hypoventil ation. From the 21 patients treated, 19 decided to continue with long- term NIPPV, one with oxygen, and one refused treatment. We conclude th at in patients with CWD who manifest nighttime oxygen desaturation and hypoventilation, early initiation of NIPPV is preferable to supplemen tal oxygen. Our results also suggest that NIPPV initiated before overt ventilatory failure could prevent its onset.