One-Lung Ventilation with High Tidal Volumes and Zero Positive End-Expiratory Pressure Is Injurious in the Isolated Rabbit Lung Model


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Abstract

We tested the hypothesis that one-lung ventilation (OLV) with high tidal volumes (Vt) and zero positive end-expiratory pressure (PEEP) may lead to ventilator-induced lung injury. In an isolated, perfused rabbit lung model, Vt and PEEP were set to avoid lung collapse and overdistension in both lungs, resulting in a straight pressure-time (P-vs-t) curve during constant flow. Animals were randomized to (a) nonprotective OLV (left lung) (n = 6), with Vt values as high as before randomization and zero PEEP; (b) protective OLV (left lung) (n = 6), with 50% reduction of Vt and maintenance of PEEP as before randomization; and (c) control group (n = 6), with ventilation of two lungs as before randomization. The nonprotective OLV was associated with significantly smaller degrees of collapse and overdistension in the ventilated lung (P < 0.001). Peak inspiratory pressure values were higher in the nonprotective OLV group (P < 0.001) and increased progressively throughout the observation period (P < 0.01). The mean pulmonary artery pressure and lung weight gain values, as well as the concentration of thromboxane B2, were comparatively higher in the nonprotective OLV group (P < 0.05). A ventilatory strategy with Vt values as high as those used in the clinical setting and zero PEEP leads to ventilator-induced lung injury in this model of OLV, but this can be minimized with Vt and PEEP values set to avoid lung overdistension and collapse.

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