The degree of muscle relaxation requested by the surgens during upper abdominal surgery.

The degree of muscle relaxation required for the abdominal surgery should differ at different phase of operation. To test this hypothesis muscle relaxation was assessed subjectively by the surgeon and the results were compared with quantitative observations of the degree of response depression to train of four (t4) stimulation at various stages of surgery. Maximum relaxation, with a t4 ratio of less than 10%, was required immediately after the skin incision and during closure of the abdominal wall, while the requirement was minimal during the major part of surgery when the intra-abdominal procedures were performed.