Effects of body temperature on ventilator-induced lung injury

Abstract

Purpose To evaluate the effects of body temperature on ventilator-induced lung injury. Material and Methods Thirty-four male Sprague-Dawley rats were randomized into 6 groups based on their body temperature (normothermia, 37 ± 1°C; hypothermia, 31 ± 1°C; hyperthermia, 41 ± 1°C). Ventilator-induced lung injury was achieved by ventilating for 1 hour with pressure-controlled ventilation mode set at peak inspiratory pressure (PIP) of 30 cmH 2O (high pressure, or HP) and positive end-expiratory pressure (PEEP) of 0 cmH 2O. In control subjects, PIP was set at 14 cmH 2O (low pressure, or LP) and PEEP set at 0 cmH 2O. Systemic chemokine and cytokine (tumor necrosis factor α, interleukin 1 β, interleukin 6, and monocyte chemoatractant protein 1) levels were measured. The lungs were assessed for histological changes. Results Serum chemokines and cytokines were significantly elevated in the hyperthermia HP group compared with all 3 groups, LP (control), normothermia HP, and hypothermia HP. Oxygenation was better but not statistically significant in hypothermia HP compared with other HP groups. Cumulative mean histology scores were higher in hyperthermia HP and normothermia HP groups compared with control and normothermia HP groups. Conclusions Concomitant hyperthermia increased systemic inflammatory response during HP ventilation. Although hypothermia decreased local inflammation in the lung, it did not completely attenuate systemic inflammatory response associated with HP ventilation.