Respiratory compliance during laparoscopic hiatal and inguinal hernia repair

Purpose: Side stream spirometry with dynamic compliance displayed as pressure-volume loops, has enabled early detection of CO2 pneumothorax during pneumoperitoneum. We compared dynamic compliance profiles of two laparoscopic procedures with different patient positions. Methods: In 26 patients, scheduled either for laparoscopic fundoplication in ahead-up tilt or inguinal herniorrhaphy in a head-down tilt, dynamic compliance was measured with continuous spirometry from anaesthesia induction until skin closure. Control pressure-volume loops were saved in the horizontal position before surgery and compared with succeeding loops in the head-up / head-down tilt before pneumoperitoneum, during pneumoperitoneum in the horizontal and the tilt position, after evacuation of pneumoperitoneum in the tilt and finally in the horizontal position. Results: Pneumoperitoneum reduced compliance in both groups by 35% (P < 0.01). Head-down tilt decreased compliance by 12% before and during pneumoperitoneum (P < 0.01). Head-up tilt increased compliance by 4% before pneumoperitoneum (P < 0.05), but during pneumoperitoneum it had no effect, After evacuation of pneumoperitoneum compliance returned immediately to control in head-up tilt, but remained reduced in head-down tilt and was not at control after adopting horizontal position (P < 0.05). Difference between the groups was significant (P < 0.01) in the head-up / head-down tilt before, during and immediately after pneumoperitoneum. Conclusion: Both pneumoperitoneum and head-up and head-down positions had characteristic effects on dynamic compliance, Simultaneous display of sequential pressure-volume loops enabled immediate detection of changes in respiratory mechanics.