Figure 71-10 Change in vital capacity seen after surgical procedures in various sites. All patients manifest the lowest vital capacity on the day of surgery. Upper abdominal surgery is associated with the greatest reduction in vital capacity, and spinal surgery is associated with the least. (Redrawn from Ali J, Weisel RD, Layug AB, et al: Consequences of postoperative alterations in respiratory mechanics. Am J Surg 128:376, 1974.)