Hands-up positioning during asymmetric sternal retraction for internal mammary artery harvest: a possible method to reduce brachial plexus injury.

This study compares the hands-up (HU) with the arms at side (AAS) position to determine whether one is beneficial in reducing brachial plexus stress during asymmetric sternal retraction. Eighty patients undergoing cardiac surgery were assigned to either Group 1 (AAS) or Group 2 (HU). Perioperative neurologic evaluations of the brachial plexus were performed and somatosensory evoked potentials (SSEPs) were collected during internal mammary artery harvest using asymmetric sternal retraction. Demographic data, SSEP changes, and postoperative brachial plexus symptoms were compared between groups. SSEP amplitude decreased in 95% of all patients during retractor placement with substantial decreases (> 50%) observed on the left side in 50% of the AAS and 35% of the HU patients. Amplitude recovery was normally seen in both groups after asymmetric retractor removal. Similar changes were noted, to a lesser degree, on the right side. During asymmetric sternal retraction, HU positioning offered minimal benefit in reducing brachial plexus stress as measured by SSEP. Three of the seven AAS patients who reported brachial plexus symptoms had an ulnar nerve distribution of injury. However, none of the four patients with plexus symptoms in the HU group had ulnar nerve problems, suggesting that the higher incidence of postoperative symptoms observed with AAS positioning may occur from ulnar nerve compression.