Effect of Hypoventilation on bleeding during hepatic resection - A randomized controlled trial

Hypothesis: Blood loss in hepatic resection is an important determinant of operative outcome. Objective: To clarify whether reducing the tidal volume would be effective in decreasing blood loss during liver transection. Design: Randomized controlled trial. Setting: University hospital. Patients: Eighty patients scheduled to undergo hepatic resection were randomly assigned to receive liver transection under normoventilation (n = 40) or hypoventilation (n = 40). Interventions: During liver transection, in the normoventilation group, the tidal volume was 10 mL/kg and the respiratory rate was 10/min in the hypoventilation group, the tidal volume was reduced to 4 mL/kg and respiratory rate was increased to 15/min. Liver transection was performed under total or selective inflow occlusion. Main Outcome Measure: Blood loss. Results: Between the normoventilation and hypoventilation groups, no significant difference was found in total blood loss (median [range]: 630 mL [72-3600 mL] vs 630 mL [120-3520 mL]; P = .44) or blood loss per transection area (median [range]: 7.3 mL/cm(2) [1.2-55.4 mL/cm(2)] vs 9.8 mL/cm(2) [0.9-79.9 mL/cm(2)]; P=.55). During liver transection, the central venous pressure was significantly reduced in the hypoventilation group than in the normoventilation group (median [range]: -0.7 cm H2O [-3.0 to 1.8 cm H2O] vs -0.2 cm H2O [-4.0 to 2.0 cm H2O]; P=.007). The maximum end-tidal carbon dioxide level in the hypoventilation group was significantly higher than that in the normoventilation group (maximum [range]: 50 mm Hg [28-66 mm Hg] vs 37 mm Hg [27-60 mm Hg]; P<.001). Transection time, postoperative liver function, hospitalization length, morbidity, and mortality were similar in the 2 groups. Conclusion: This randomized trial suggested no beneficial effect of reduction of tidal volume on bleeding during hepatic resection.