Anesthesia (10)

Abstract

Brachial plexus anesthesia with verapamil and/or morphine. (Baystate Medical Center and the Tufts University School of Medicine, Springfield, MA) Anesth Analg 2000;91:379–383.This study examined the analgesic effects of administering morphine, verapamil, or its combination into the brachial plexus sheath with lidocaine in 75 patients undergoing upper extremity orthopedic surgery. All patients received brachial plexus anesthesia with 40 mL of 1.5% lidocaine and epinephrine 5 μg/mL. Patients were randomized to 1 of 5 groups: Group 1 received IV saline; Group 2 received IV verapamil 2.5 mg and morphine 5 mg; Group 3 received IV verapamil 2.5 mg and morphine 5 mg was added to the lidocaine solution; Group 4 received IV morphine 5 mg and verapamil 2.5 mg was added to the lidocaine solution; and Group 5 received verapamil 2.5 mg and morphine 5 mg was added to the lidocaine solution. Postoperatively, patients rated their pain (0–10) at 1, 6, 12, and 24 h. Patients were instructed to take 1 acetaminophen 325 mg/oxycodone 5 mg tablet every 3 h whenever the pain score exceeded 3. Analgesic duration was significantly increased in those patients receiving brachial plexus blocks with morphine (Groups 3 and 5) (P < 0.005). The total 24 h acetaminophen/oxycodone was also less in Groups 3 and 5 (P < 0.03). Duration of anesthesia (time of abolition of pinprick response) was significantly increased in those patients receiving brachial plexus blocks with verapamil (Groups 4 and 5) (P = 0.002). Conclude that the addition of verapamil to the brachial plexus block with lidocaine can prolong the duration of sensory anesthesia, but it had no effect on analgesic duration of 24‐h analgesic use. Comment by Alan David Kaye, MD, PhD.It is well established that calcium channel blockers potentiate analgesic effects of both local anesthetics and opioids. A desire for improvement of the quality and duration of brachial plexus blockade has led many investigators to study various agents in addition to standard local anesthetics. This interesting double‐blinded study involving 82 patients scheduled for elective upper extremity orthopedic surgery involved 5 groups. Interestingly, the combination of verapamil and morphine via the brachial plexus did not provide any additional analgesic effect, which is different than previous studies. The subjectivity of telephone data and the relatively small sample size in each arm of this study make statistically significant findings harder to ascertain and relevant changes in clinical practice less convincing. Further, the authors do not appropriately note the complexity of calcium channel pharmacology and its overall role in opioid as well as local anesthetic modulation. Future studies with more precise endpoints for efficacy and duration are warranted if clinical practice is to be altered and accepted by the practitioner.