SOMATOSENSORY-EVOKED POTENTIAL MONITORING DURING CARDIAC-SURGERY - ANEXAMINATION OF BRACHIAL-PLEXUS DYSFUNCTION

Objective: To observe the effects of the Favoloro and sternal retracto rs on the ulnar and median nerve somatosensory evoked potentials (SSEP s) and to identify any relationship with postoperative brachial plexus injury. Design: Prospective study. Setting: University hospital. Part icipants: Twenty cardiac patients. Interventions: SSEPs were studied i n patients undergoing cardiac surgery using normothermic cardiopulmona ry bypass, Evoked potentials were obtained from bilateral median and u lnar nerves. Measurements: The incidence of nerve-specific SSEP change s and their temporal relationship to retractor usage were determined. The overall incidence of SSEP changes was 75%. There were no differenc es (p > 0.05) between the group showing changes (n = 15) and the group with no changes (n = 5) with respect to age, body surface area, weigh t, cross-clamp or cardiopulmonary bypass times, There also were no dif ferences (p > 0.05) between the frequencies of left- and right-sided c hanges, or in nerve-specific SSEP changes, Seventy-four percent of SSE P changes correlated with retractor usage. No SSEP changes were associ ated with the Favoloro retractor, Significant SSEP depression, assesse d by either percentage reduction in amplitude or persistent amplitude reduction, occurred in the absence of postoperative neurological defic its. There were no detected postoperative brachial plexus injuries. Co nclusions: SSEP changes correlate with the use of the sternal retracto r but not the Favoloro retractor. It was not possible to replicate the results of previous investigators in predicting postoperative neurolo gical deficits based on the SSEP changes, and therefore the routine ap plication of SSEP as a monitor cannot be recommended on the basis on t hese data. Copyright (C) 1997 by W.B. Saunders Company.