[Noninvasive ventilator support in patients with chronic obstructive pulmonary disease. A comparison of 2 methods]

The external high frequency oscillation around a negative baseline (EHFO-NB) is a new mode of non-invasive ventilatory support which could replace or complement nasal intermittent positive pressure ventilation (NIPPV) for treatment of patients with chronic obstructive pulmonary disease, both in the decompensation phases and as preventive measure in intercrisis periods. This was a prospective study in which tolerance and short term effects on acid-base balance and gas interchange of both NIPPV and EHFO-NB in twenty patients with severe chronic obstructive pulmonary disease were compared. With both methods similar decrease in PaCO2 and increases in pH were observed, with decrease and increase in respiratory frequency when using NIPPV and EHFO-NB, respectively; the latter in association with the high oscillation frequencies used. While an improvement of SaO2 and no changes in PaO2 and intrapulmonary shunt were observed on NIPPV, a decrease was observed in the SaO2 and an increase in the shunt on EHFO-NB. Comfort of patients, improvement of perceived sensation of dyspnea, and the absence of complications were similar with both methods. While on NIPPV, 75 per cent of patients required a short period of training and continuous supervision.