DIAPHRAGM DYSFUNCTION INDUCED BY UPPER ABDOMINAL-SURGERY - ROLE OF POSTOPERATIVE PAIN

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Abstract
Effects of upper abdominal surgery on diaphragmatic function were studied in 5 patients. During quiet tidal breathing, the volume displacement of the abdomen within the tidal volume (Vab/VT) and the ratio of abdominal and transdiaphragmatic pressure changes (.DELTA.Pab/.delta.Pdi), taken as an index of the diaphragmatic contribution to the breathing process, decreased significantly on the 1st postoperative day (P < 0.001); in 2 patients, a cephalad paradoxical motion of the diaphragm during inspiration was observed. Diaphragmatic dysfunction also occurred during maximal inspiratory efforts as shown by the significant fall in maximal static transdiaphragmatic pressure (Pdimax) and cephalocaudal diaphragmatic displacement on the 1st (P < 0.001) and 3rd (P < 0.001) postoperative days. On the 1st postoperative day, opiate epidural analgesia did not modify Vab/VT, .DELTA.Pab/.DELTA.Pdi and Pdimax. These parameters spontaneously returned towards control values on the 7th postoperative day. Upper abdominal surgery induces a marked diaphragmatic dysfunction lasting about 1 wk and it is not suppressed by postoperative pain relief. The mechanism of this dysfunction remains to be determined. It may be the main cause of the postoperative pulmonary restrictive pattern.