External high-frequency ventilation in severe chronic obstructive pulmonary disease

We studied the effect of external high-frequency oscillation using an oscillator (Hayek oscillator [HO]) on 20 patients with severe chronic obstructive pulmonary disease (COPD). Of the 20 patients, 10 were eucapnic and 10 were hypercapnic. The HO generated frequencies from 60 to 140 cycles/min at an amplitude of 36 cm H2O (-26 to +10) and at an inspiratory/expiratory (I/E) ratio of 1:1. The results show that the HO is a powerful ventilator, reducing end-tidal PCO2 (PETCO2) by 6.7 to 9.1 mm Hg in eucapnic patients and by 6.1 to 7.9 mm Hg in hypercapnic patients. The oxygen saturation increased by 2 to 2.87 percent in the eucapnic patients and by 2.6 to 3.7 percent in the hypercapnic group in the various frequencies. The rate of elimination of CO2 and the levels of PETCO2 achieved within a short time were superior to those reported with other external ventilators. We conclude that the HO can be effectively used in severe COPD and respiratory failure for (1) assisting ventilation, thus replacing intubation and conventional mechanical ventilation, and (2) relieving muscle fatigue in short sessions.