Influence of intra-abdominal pressure on ventilatory mechanical power delivery and respiratory driving pressure during laparoscopic cholecystectomy: A prospective cohort study.

Abstract

Pneumoperitoneum creation for laparoscopic surgery increases the intraabdominal pressure and causes alveolar atelectasis. We investigated the influence of an increase in intra-abdominal pressure (IAP) on ventilatory mechanical power (MP) delivery during pneumoperitoneum creation for laparoscopic cholecystectomy. In a prospective cohort design, we enrolled 42 patients undergoing laparoscopic cholecystectomy. During pneumoperitoneum creation, the IAP was sequentially raised to three predefined IAP levels (8, 11 and 14 mmHg), keeping identical ventilatory settings (timepoints T1, T2, and T3). After that, positive end-expiratory pressure (PEEP) was sequentially raised from 5 to 8 to 11 cmH2O (timepoint T4 and T5). The primary outcome included ventilatory MP delivery at each timepoint. Other variables included respiratory driving pressure (DP), airway resistance (AR), and respiratory compliance (RC). The MP increased linearly with a rise in IAP from T1 to T3 (r = 0.71, P < 0.001); the MP increased by 0.19 per unit rise in IAP (effect size 0.90, P < 0.001). A similar positive correlation was also observed between DP and IAP from T1 to T3 (r = 0.73, P < 0.001); the DP increased by 0.72 per unit rise in IAP (effect size 0.89, P < 0.001). The MP increased significantly on increasing PEEP from T3 to T5, while the DP decreased concomitantly (P < 0.001). The AR increased significantly from T1 to T3, while RC decreased concomitantly; vice-versa was observed at T4 and T5 (P < 0.001). The ventilatory MP delivery rises linearly with an increase in IAP. Targeting an IAP-guided MP level could be an attractive approach to minimize lung injury.