Utility of transesophageal echocardiography in identifying spinal canal structures and epidural catheter position: a prospective observational study of intraoperative hemodynamics and postoperative analgesia

The aims of this study were to determine the utility of transesophageal echocardiography (TEE) for identifying spinal canal structures and epidural catheter position and to assess the effect of catheter position on intraoperative hemodynamics and quality of postoperative analgesia.

Twenty-six adult patients undergoing thoracic surgery were included in this prospective, observational study. An epidural catheter was inserted 7.5 cm or more into the thoracic epidural space using a midline approach and a loss-of-resistance technique. A pediatric TEE probe was inserted after induction of general anesthesia. It was used to identify the spinal canal structures, the catheter tip position in the epidural space, and the spread of injected local anesthetic. Intraoperative hemodynamics, postoperative visual analogue scale (VAS) pain scores, and the need for rescue epidural doses were recorded and compared between groups determined by their catheter position.

Two subjects were excluded from the study because of an intrathecally positioned epidural catheter. The remaining 24 subjects were divided into two groups based on TEE-determined epidural catheter position: posterior (Gr-P) or lateral (Gr-L). Spinal canal structures and the epidural catheter was successfully identified in all patients. The epidural catheter was located posteriorly in 20 (83%) patients and laterally in four (17%) patients. The spread of the local anesthetic was bilateral in all Gr-P patients, whereas it was unilateral in all but one of the Gr-L patients. Compared to Gr-P patients, Gr-L patients had higher heart rates and blood pressures at various time points after local anesthetic administration until the end of surgery (P = 0.02 to < 0.001). Postoperative VAS scores (P = 0.02) and the median number of rescue analgesic doses required during the intraoperative and postoperative periods were also higher in Gr-L patients (P < 0.001).

Transesophageal echocardiography reliably identified spinal canal structures and the position of epidural catheters in the epidural space in adult patients. Posteriorly located epidural catheters appear to provide better epidural analgesia than laterally situated catheters.