Oxygenation during ventilation by high-frequency oscillation in dogs with acute lung injury

The effect of ventilation by high-frequency oscillation (HFO) on gas exchange in the abnormal lung is not well defined. In this study the efficiency of oxygenation by HFO (stroke volume 2.5 to 3.5 ml/kg, frequency 15 to 30 Hz) and by conventional mechanical ventilation (CMV) (tidal volume 15 to 20 ml/kg, frequency 8 to 15 breath/min) was compared in dogs with acute lung injury. Sixteen normal animals were studied under general anesthesia (halothane) on day 0 (control) and then injected intraperitoneally with 10 mg/kg of paraquat in divided doses over 3 consecutive days. Eight dogs were restudied on day 4 (moderate lung injury) and the other eight dogs on day 8 (more severe lung injury). With acute lung injury there was a progressive decrease in total lung capacity, decrease in lung compliance, and hypoxemia. In the moderate lung injury group, at equal alveolar ventilation, HFO resulted in a significant improvement in oxygenation (PaO2 95 to 104 torr) with a corresponding increase in mean lung volume when compared with CMV. In the severe lung injury animals, there were no significant differences in oxygenation or in mean lung volume between HFO and CMV.