Prediction of Effective Post-Operative Epidural Anesthesia Using Hemodynamic Changes Detected by Endotracheal Cardiac Output Monitor (ECOM)

Abstract

Background: Epidural anesthesia after abdominal surgery results in improved postoperative pain relief but has up to a 30% failure rate. Hemodynamic changes after epidural administration of local anesthetics may provide parameters to predict dermatomal blockade and effective pain control in the postoperative period. The Endotracheal Cardiac Output Monitor (ECOM) provides continuous measurements of stroke volume (SV), cardiac output (CO) cardiac index (CI) and systemic vascular resistance (SVR). We hypothesized that the changes in hemodynamic parameters measured by the ECOM monitor along with changes in systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) would predict effective epidural anesthesia. Methods: 19 patients undergoing intra-abdominal surgery were enrolled. After placement of an epidural catheter and establishment of general anesthesia hemodynamics were recorded in 15-minute intervals using the ECOM monitor. At the start of abdominal closure epidural catheters were loaded with two 5 ml boluses of 0.25% bupivacaine in ten-minute intervals. Hemodynamic parameters where then recorded at five-minute intervals until conclusion of surgery. The number of dermatomes blocked, post anesthesia care unit (PACU) pain scores, average 24-hour pain scores, and patient satisfaction were recorded.Results: Significant reduction was observed in SBP, DBP, MAP and in SVR, and increases were seen in CO and CI after starting epidural anesthesia. From the parameters measured, only a significant reduction of SVR accompanied with higher level of dermatomes blocked, and lower average 24-hour pain scores. At the sane time patients without significant SVR change had relatively low pain scores, high patient satisfaction and required the same amount of pain medications. Conclusion: Changes in SVR detected by the ECOM monitor might help to predict an effective epidural system but its clinical relevance needs to be further evaluated.