Interscalene block, continuous local anesthetic infusion similarly effective for post-arthroscopic shoulder surgery pain

While patients in the pain pump group had better pain scores up to 4 days postop, the difference was not statistically significant.

Interscalene block and the continuous subacromial infusion of a local anesthetic are similarly effective for relieving pain after arthroscopic rotator cuff repair, a prospective study found.

Both pain control methods also were associated with similar complication rates and total costs, the study authors noted.

Darby Webb, MD, and colleagues compared the efficacy of the two anesthetic modalities in a study of 56 consecutive patients. All patients underwent outpatient arthroscopic shoulder surgery performed by a single surgeon using general anesthesia. Investigators randomly assigned 29 patients to receive preoperative interscalene block, administered as a one-time injection of 0.5% bupivacaine with epinephrine (1:200,000).

The remaining 27 were assigned to receive patients a continuous infusion of a local anesthetic — 0.5% bupivacaine — delivered via a pain pump [Pain Care 3000; Breg] implanted into the subacromial space, according to the study, published in Arthroscopy. The patient removed the pain pump at 48 hours postoperatively.

Investigators asked each patient to record their subjective pain levels in a diary using the Visual Analog Scale (VAS) every 12 hours up to 48 hours postop, and then daily on day 3 through day 7 postoperatively. Patients were also asked to record their medication intake during these 7 days postop.

The researchers provided patients with only two oral rescue analgesics: 800 mg ibuprofen administered orally every 12 hours, as needed, and Percocet [5 mg oxycodone and 325 mg acetaminophen; Endo Pharmaceuticals] administered once or twice orally every 4 hours, also as needed.

Total costs for each group were calculated by multiplying the total hospital charges by the ratio of annual hospital cost to charges. For the interscalene block group, costs included anesthesia staff and medication costs, and costs for the pain pump group included anesthesia staff costs, pump costs and medication costs, according to the study.

Three patients in the pain pump group were excluded from the analysis because they did not complete their entries in the pain diaries. In one of these patients, the pain pump catheter was also inadvertently removed.

"No statistically significant differences were identified for any interval over the 7-day evaluation," the authors wrote. "Overall, the pain pump group had better VAS scores from 24 hours through day 4, but this was not statistically significant."

The researchers also found no significant differences between groups in either ibuprofen use or Percocet use throughout the 7 days of follow-up. "Overall, the pain pump group had less Percocet use for the first 5 days, but this was not statistically significant," they wrote.

In addition, total costs were similar and averaged $2131.76±500.52 for the interscalene block group and $2079.77±584.58 for the pain pump group, according to the study.

For more information:
Webb D, Guttmann D, Cawley P, Lubowitz JH. Continuous infusion of a local anesthetic versus interscalene block for postoperative pain control after arthroscopic shoulder surgery. Arthroscopy. 2007;23:1006-1011.