Use of a Continuous Local Anesthetic Infusion for Pain Management after Median Sternotomy

Background-The use of large doses of opioid analgesics to treat pain after cardiac surgery can prolong the time to tracheal extubation and interfere with the recovery of the bowel and bladder function in the postoperative period. Therefore, we sought to investigate the efficacy of a continuous infusion of Bupivacaine 0.5%, at the median sternotomy site, for 48 hours after cardiac surgery in reducing the opioid analgesic requirement and improving the recovery process. Methods-In this prospective, randomized, placebo-controlled, double-blind clinical trial, 36 consenting patients undergoing open heart surgery with a standardized general anesthetic technique had two indwelling infusion catheters placed at the median sternotomy incision site at the end of surgery. The patients were randomly assigned to receive normal saline (control), Bupivacaine 0.5% via an elastomeric infusion pump at a constant rate of 4 ml/h for 48 hours. In addition, the postoperative opioid analgesic requirements and opioid-related adverse effects were recorded. The patients‟ satisfaction with their pain management was assessed at specific intervals during the postoperative period. Duration of mechanical ventilation and time of ventilation were assessed in the two groups. Results-Compared with the control group, there was a statistically significant reduction in ambulatory time 13.7+/-2.5 vs. 16.5+/-4.6 hours (P=0.03). Hospital stay was also shorter in the case group (5+/-0.6 vs. 6.1+/-0.9 with P= 0.01). Extubation time and ICU stay were not statistically significant (P= 0.93 for extubation time and P=0.70 for duration of ICU stay), and also patient satisfaction in the two groups was not statistically significant. Opioid dose, used in the case group, was 1.1+/-0.8 and in the control group was 3.7+/-1.3, with the difference being statistically important (P = 0.02). Conclusion-A continuous infusion of Bupivacaine 0.5% at 4 ml/h is effective for decreasing pain and the need for opioid analgesic medication as well as for improving patient satisfaction with pain management after cardiac surgery. Patients in the Bupivacaine-0.5% group were able to ambulate earlier, leading to a reduced length of hospital stay