From the Journal archives: Postoperative analgesia: effect on lung volumes

This study was undertaken to determine the contribution of postoperative pain to the known changes that occur to respiratory function in the postoperative period. The authors studied changes in functional residual capacity (FRC) and vital capacity (VC) either in the postanesthesia care unit or on postoperative day one in eight relatively healthy adult patients having upper abdominal surgery. These values were compared with measurements immediately before surgery. Variables were measured postoperatively during pain and then again after establishment of epidural analgesia. Epidural analgesia to a T4 sensory level resulted in a partial and statistically significant restoration of VC (from 37-55% of preoperative values) and a partial but statistically insignificant restoration of FRC (from 78-84% of preoperative values). The authors suggest that postoperative epidural analgesia may be able to decrease respiratory complications.

Wahba MW, Don HF, Craig DB. Can Anaesth Soc J 1975; 22: 519-27.

This study was undertaken to determine the contribution of postoperative pain to the known changes that occur to respiratory function in the postoperative period.

Epidural analgesia to T4 resulted in a partial and statistically significant restoration of VC (from 37-55% of preoperative values) and a partial but statistically insignificant restoration of FRC (from 78-84% of preoperative values).

Epidural analgesia has more effect on the voluntary aspects of postoperative respiration (VC) than on the involuntary changes in respiration (FRC) after upper abdominal surgery.