June 13, 2002

Analgesia for Post-Operative Pain

Commentary by Richard Rosenquist, M.D.

The inability to provide prolonged analgesia following painful surgery has been a major impediment to the expansion of outpatient surgical procedures. Major advances in the available general anesthesia drugs for that also allow for rapid recovery and discharge have outstripped the availability of outpatient analgesia of similar quality. Recent years have seen an expansion in the use of regional anesthesia/analgesia. These techniques, in combination with sedation or general anesthesia, allow rapid recovery and analgesia persisting for up to 24 hours. However, the duration of relatively severe pain frequently outlasts the duration of single shot regional anesthetics/analgesics. Multiple studies have looked at adjuvant drugs that are delivered simultaneous with local anesthetics to increase the duration of analgesia, but in most cases, the period of analgesia is shorter than the duration of significant pain. In the June 2002 issue of Anesthesiology, two studies by Rawal, et al. and Ilfeld, et al., and an accompanying editorial by Stephen Klein, describe the successful use of patient controlled regional analgesia on an outpatient basis as well as the lack of consistent education and delivery of these techniques across residency education programs and medical practice in general. The availability of improved equipment and increased evidence of the success and safety of these techniques in the outpatient setting will increase pressure on providers to learn and implement these techniques within their practices. The net result will be an improvement in the overall perioperative experience for the patient and perhaps an improvement in overall outcome based on better analgesia and an increased ability to participate in aggressive postoperative rehabilitation programs.

The authors of this study set out to compare the efficacy of bupivacaine versus ropivacaine brachial plexus analgesia following ambulatory hand surgery. An additional goal of the study was to examine the feasibility and safety of patient-controlled regional analgesia (PCRA) outside the hospital. They recruited 60 patients scheduled to undergo elective hand surgery procedures. During the preanesthesia visit, all patients were given explanations of the visual analog scale (VAS), verbal pain scoring, use of a "home pump" device and the importance of completing the diary. They were also educated about the use of PCRA. All patients received an axillary brachial plexus block and had a catheter inserted during the block for postoperative analgesia. All of the blocks were sufficient for surgery. Following completion of the surgical procedure, the blocks were allowed to wear off until the patients experienced pain. Before discharge, the patients self-administered 1 or 2 doses of PCRA (10 mls of either 0.125% bupivacaine or 0.125% ropivacaine) to confirm catheter position and efficacy and patient understanding of the home pump device. Patients were allowed to remain in the study only if it was clear that they understood the instructions. Patients were given information regarding management, catheter removal and contact numbers for questions. The catheters were left in for three days and then removed by the patient. All of the patients were also given 100 mg tablets of dextropropoxyphene to use if PCRA was ineffective.

Data was collected by asking patients to indicate their VAS before and 20 minutes after using their PCRA device. They also recorded their analgesia on a 5-grade scale, recorded comments regarding analgesia, use of rescue medication, side effects, technical problems and suggestions for improvement. They also received a call from a research nurse.

The two groups were similar with respect to the type of surgical procedure, frequency of PCRA use and the degree of postoperative analgesia. One patient in each group required dextropropoxyphene. Eighty-seven percent of patients in both groups expressed a desire to have this type of treatment in the future. On the day of the surgery, more patients were satisfied with ropivacaine analgesia than bupivacaine analgesia. This was primarily due to a greater degree of weakness and numbness associated with bupivacaine on day one. None of the patients exhibited any signs or symptoms of local anesthetic toxicity or catheter site infections.

The authors concluded that this study demonstrated the feasibility of self-administering local anesthetic using a balloon pump for postoperative pain relief outside of the hospital. They also concluded that both ropivacaine and bupivacaine provided effective analgesia and high satisfaction with PCRA. They emphasized the importance of appropriate patient selection, follow-up telephone call and 24-hour access to anesthesiology services as prerequisites for successful use of this technique.

The authors of this double-blinded, placebo-controlled trial investigated the efficacy of patient-controlled regional analgesia delivered via an infraclavicular brachial plexus perineural catheter using a portable, large volume infusion pump in patients undergoing painful upper extremity orthopedic procedures.

The authors recruited 30 patients who subsequently underwent placement of an infraclavicular nerve block and catheter. All blocks were dosed with 50cc of the anesthetic solution followed by placement of the catheter. Patients were withdrawn from the study if sensory block failed to develop after 15 minutes or the catheter was intravascular. Patients were given only the block or received a general anesthetic as well. Postoperatively, patients were randomized to either an infusion of ropivacaine 0.2% at 8cc/hr or sterile saline 0.9% at 8 cc/hr. When patients met discharge criteria, the catheters were gently aspirated and then injected with 10 cc of study solution containing 30 ug of fresh epinephrine to rule out intravascular placement. If the test was negative, the pumps were attached to a portable, programmable, battery-powered, mechanical infusion pump with a reservoir containing 550 cc of study solution. The initial infusion was 8 cc/hr with a 2 cc patient-controlled bolus available every 20 minutes. The patient and caretaker were given postoperative instructions and a prescription for oxycodone 5 mg with acetaminophen 500 mg that was identical to patients undergoing similar operations. In the event of breakthrough pain, the patients were instructed to use the bolus function first and then to take the oral narcotic if the pain had not resolved after 20 minutes. The patients were able to contact a physician at any time during the study period. The authors examined pain scores at rest and with limb motion, oral narcotic use, narcotic-related side effects and sleep quality. They were also questioned about symptoms of local anesthetic toxicity and the catheter site. The patient's caretakers removed the catheter on postoperative day 2. Finally, patient satisfaction was assessed and the pump was mailed back to the authors in a preaddressed, stamped envelope the following morning.

Thirty-five patients were initially recruited, but 5 had to be withdrawn due to intravascular catheter placement. The remaining patients were divided equally between the two groups. The patients receiving ropivacaine had significantly less postoperative pain when compared to the saline infusion group. The average pain with movement on postoperative day 1 was 6.1 ± 2.3 for the saline group versus 2.5 ± 1.6 for the ropivacaine group (P< 0.001). Oral narcotic use and narcotic related side effects were significantly decreased in the ropivacaine group. On postoperative day 1, mean opioid tablets consumption was 5.5 ± 2.4 for the saline group and 1.7 ± 1.6 for the ropivacaine group. Sleep disturbance was significantly greater in the saline group. Overall satisfaction was significantly greater in the ropivacaine group. No catheter or local anesthetic related complications occurred.

The authors concluded that infraclavicular brachial plexus infusion with ropivacaine using a portable mechanical pump is an effective means of providing postoperative analgesia in outpatients following moderately painful upper extremity orthopedic surgery.

ABSTRACT

No abstract available