Postoperative Analgesia by Continuous Extradural Infusion of Ropivacaine After Upper Abdominal Surgery

Abstract

Comment: The authors adopted a different approach to traditional dose-response studies. Instead of using one concentration of ropivacaine and varying the infusion rate, they used differing concentrations of ropivacaine at the fixed rate of 10 mL/hr. With these methods, the authors demonstrated superior analgesia as measured by a visual analog scale for pain at rest and on coughing with the 0.2 and the 0.3% concentrations. The 0.3% concentration had the lowest intravenous morphine requirement during the study period. One of ten patients in each of the 0.2 and 0.3% groups developed motor block, whereas no motor block occurred in the control or 0.1% infusion groups. The 0.2 and the 0.3% concentrations were also associated with a higher incidence of hypotension that was easily treated with an increase in the intravenous infusion rate. Thus, the 0.3% concentration seems to be the best epidural solution for the immediate 24-hr postoperative period in terms of achieving analgesia after major upper abdominal surgery without the addition of neuraxial opioids. One major risk following abdominal surgery is pulmonary infection.1 Coughing and deep breathing are important to prevent both atelectasis and infection. The benefit of decreased pain with coughing outweighs the small risk of minor hypotension. Furthermore, patients will not be ambulating during the first 24-hr period. It would be interesting to extend this study beyond the 24-hr period to determine whether there would be any benefit to then switching to the lower concentrations.