The effects of inspiratory to expiratory ratio on ventilation and oxygenation during high frequency partial liquid ventilation in a rabbit model of acute lung injury

Abstract

Background:We examined the effects of varying inspiratory to expiratory (I：E) ratio on gas exchange and hemodynamics during high frequency partial liquid ventilation (HFPLV), a combination of high frequency ventilation (HFV) and partial liquid ventilation (PLV), in a rabbit model of acute lung injury.Methods: Twelve rabbits treated with repeated saline lavage were divided into two groups. In the HFPL group (n = 6), 6 ml/kg of perfluorodecaline was administered through the endotracheal tube. Rabbits in this group and in the HFJ group (n = 6) were treated with high frequency jet ventilation (HFJV) at I：E ratios of 1：1, 1：2, and 1：3 for 15 minutes, and arterial blood gas, mixed venous blood gas and hemodynamic parameters were measured.Results: We observed no significant respiratory and hemodynamic differences between the two groups. At an I：E ratio of 1：1, the PaO2 was significantly higher, and the shunt rate and PaCO2 were significantly lower in both groups, compared with I：E ratios of 1：2 and 1：3. Cardiac output at the 1：3 I：E ratio was significantly higher than at 1：1.Conclusions: These findings indicate that, in this model, a 1：1 I：E ratio was superior for oxygenation and ventilation than I：E ratios of 1：2 or 1：3, while having no detrimental effects on hemodynamics.