Objective: To determine the effect of selective right lung ventilation on gas exchange and hemodynarnics when compared with bilateral lung ventilation in a porcine open-chest shock model.Methods: 4 randomized, controlled laboratory investigation was performed using a static hemorrhagic shock model in 12 adult swine undergoing thoracotomy. The animals were subjected to a fixed 40% circulating blood volume hemorrhage over 20 minutes. Each animal was then assigned to either a tracheal (control) or a right mainstem (experimental) intubation group. Minute ventilation was held constant in both groups and tidal volumes were decreased by 33% in the right mainstem intubation group. Following intubation and left lateral thoracotomy. another 20% fixed-volume hemorrhage was instituted simultaneously with IV crystalloid and whole blood resuscitation for both groups over 30 minutes. Heart rate. blood pressure. and arterial blood gases were measured at 5-minute intervals.Results: There was no significant difference between the control and experimental groups for any of the measured variables. including mean arterial pressure, pH, partial arterial pressure of CO? (Paco,), and Pao,. over time. All animals survived the study protocol.Conclusion: Selective right lung ventilation has no detrimental effect on gas exchange or hemodynarnics when compared with standard bilateral lung ventilation in a porcine open-chest shock model.