Interscalene Regional Anesthesia for Shoulder Surgery

Bishop, Julie Y. MD; Sprague, Mark MD; Gelber, Jonathan MS; Krol, Marina PhD; Rosenblatt, Meg A. MD; Gladstone, James MD; Flatow, Evan L. MD

Journal of Bone & Joint Surgery - American Volume:
doi: 10.2106/JBJS.D.02003
Scientific Articles

Background: Despite a trend toward the use of regional anesthesia for orthopaedic procedures, there has been resistance to the use of interscalene regional block for shoulder surgery because of concerns about failed blocks and potential complications.

Methods: We retrospectively reviewed the cases of 568 consecutive patients who had shoulder surgery under interscalene regional block in a tertiary-care, university-based practice with an anesthesiology residency program. The blocks were performed by a group of anesthesiologists who were dedicated to the concept of regional anesthesia in their practice. Complete anesthetic and orthopaedic records were available for 547 patients. The surgical procedure, planned type of anesthesia, occurrence of block failure, and the presence of complications were noted.

Results: Of the 547 patients, 295 underwent an arthroscopic procedure and 252 (including eighty who had an arthroplasty) underwent an open procedure. General anesthesia was the initial planned choice for sixty-nine patients because of the complexity or duration of the procedure, the anatomic location, or patient insistence. Thirty-four of the sixty-nine patients also received an interscalene regional block. Interscalene regional block alone was planned for 478 patients. A total of 462 patients (97%) had a successful block whereas sixteen required general anesthesia because the block was inadequate. The success of the block was independent of the type or length of the surgery. No patient had a seizure, pneumothorax, cardiac event, or other major complication. Twelve (2.3%) of the 512 patients who had a block had minor complications, which included sensory neuropathy in eleven patients and a complex regional pain syndrome that resolved at three months in one patient. For ten of the eleven patients, the neuropathy had resolved by six months.

Conclusions: Interscalene regional block provides effective anesthesia for most types of shoulder surgery, including arthroplasty and fracture fixation. When administered by an anesthesiologist committed to and skilled in the technique, the block has an excellent rate of success and is associated with a relatively low complication rate.

Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Author Information

1 Columbus Bone, Joint and Hand Surgeons, Inc., 815 West Broad Street, Columbus, OH 43222

2 The Leni and Peter W. May Department of Orthopaedics (M.S., J. Gelber, J. Gladstone, and E.L.F.), Box 1188, and Department of Anesthesiology (M.K. and M.A.R.), Box 1010, Mount Sinai Hospital, 5 East 98th Street, New York, NY 10029. E-mail address for E.L. Flatow:

Article Outline

Interscalene block regional anesthesia offers many advantages over general anesthesia for both arthroscopic and open surgeries of the shoulder1-5. It provides excellent intraoperative anesthesia and muscle relaxation1 as well as analgesia that continues into the postoperative period. Airway manipulations are avoided, postoperative nausea and vomiting are diminished, the stay in the postanesthesia care unit is shortened2, and fewer nursing interventions in the postanesthesia care unit are required. The need for overnight hospitalization secondary to pain, postoperative nausea or vomiting, or sedation is decreased, as are nonsurgical operating-room times3. For patients managed in the outpatient setting, interscalene regional block is associated with the ability to bypass Phase-I postoperative anesthesia care (acute) and allows earlier discharge4. Interscalene regional block is associated with a high degree of patient acceptance; patients returning for procedures on the contralateral shoulder overwhelmingly prefer the regional technique5. Interscalene regional block has been associated with technical success, when performed by dedicated individuals, and with a low rate of long-term complications6, yet resistance to the use of interscalene regional block continues because of concerns about failed blocks and potential complications. We describe our 2.5-year experience with use of interscalene regional block for shoulder surgery in a university teaching hospital.

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Materials and Methods

After obtaining institutional review board approval, we performed a retrospective chart review of 568 consecutive patients undergoing shoulder surgery in a tertiary-care university medical center with an anesthesiology residency program. Complete anesthetic and orthopaedic records were available for 547 patients. Intraoperative anesthetic records were obtained from the anesthesia information management system (CompuRecord; Philips, Andover, Massachusetts). All postoperative records, including physician notes on patient follow-up visits, were obtained from the senior author (E.L.F.). The surgical procedure and planned type of anesthesia, i.e., general anesthesia alone or isolated interscalene block, or both, were recorded. The exclusion criteria for interscalene regional block included coagulopathy and patient refusal. In patients for whom interscalene regional block was the planned sole anesthetic agent, any reason for conversion to general anesthesia was considered a block failure.

After an intravenous line was inserted and monitors were placed, the patients were sedated according to the individual preference of the attending anesthesiologist. The patients received ≤4 mg midazolam with or without 100 μg fentanyl. A nerve stimulator technique with use of Stimuplex needles and stimulators (B. Braun Medical, Bethlehem, Pennsylvania) was employed in all patients. After sterile preparation of the arm, the interscalene groove was identified and stimulation of ≤0.4 mA of the deltoid, triceps, or biceps muscles or forearm was accepted as evidence of the necessary proximity of the needle to the nerve. Either 40 mL of 0.5% bupivacaine or 20 mL of 0.5% bupivacaine with 20 mL of 1.5% mepivacaine, both with or without epinephrine 1:200,000, was then injected at the discretion of the anesthesiologist.

The need for intraoperative administration of propofol, fentanyl, or midazolam as well as the rate and amount of those medications were noted. Midazolam and propofol were used to provide amnesia and sedation, primarily at the request of the patient. Fentanyl was given to alleviate any pain due to the positioning. An additional field block, containing a 50:50 mixture of 1% lidocaine with epinephrine and 0.25% bupivacaine, was given to all patients receiving interscalene block alone. This was administered with a 22-gauge needle by the surgeon after the sterile preparation and draping but before the incision. It was placed in the supraclavicular region and in the axillary region to block the suprascapular nerves in all patients undergoing arthroscopy, or to provide a distal incisional block in all patients undergoing total shoulder arthroplasty, as these nerves are routinely missed by the interscalene regional block. The amount given was recorded for each patient, and the average amount given overall was calculated. All operations, with the exception of latissimus-teres major tendon transfers and scapulothoracic arthroscopies, were performed with the patient in the beach-chair position. Interscalene regional block with the patient in the lateral position, while technically possible, is not very comfortable for the patient. Not only is the traction on the involved arm painful but lying motionless for long periods on the nonanesthetized shoulder can be uncomfortable. Depending upon the body habitus of the patient and the evaluation of the airway, it is possible to administer sedation to allow the patient to tolerate the position, but, most frequently, we combine a light general anesthetic with the interscalene regional block if we use the lateral position.

Surgical and anesthesia times were recorded. Procedure length was defined as the total operative time from the incision to the skin closure. Anesthesia time included the procedure length as well as the time from the arrival of the patient in the operating room to the beginning of the procedure and then from the end of the procedure to the departure of the patient from the operating room. If the blocks were performed in the holding area, the anesthesia automatic record keeper (a computerized system that automatically enters the vital signs and the hemodynamic and ventilatory parameters into the patient's anesthetic record rather than having them entered manually) was timed to reflect the starting time of anesthesia, as patient care was being delivered. The difference between the procedure length and the anesthesia time was then calculated and termed “nonsurgical time.” The nonsurgical time for the patients who received interscalene regional block alone and those managed with general anesthesia was compared. The preoperative and postoperative nonsurgical times were not separately analyzed.

Problems during the administration of the block were recorded on the anesthesia information management system. Acute complications included any signs of local anesthetic intoxication, blood aspiration, cardiac events, respiratory distress, pneumothorax, or hematoma. Nonacute complications were noted from the records of the postoperative anesthesia care unit and orthopaedic office records and included any postoperative evidence of motor or sensory deficits, paresthesias, dysesthesias, and any pain or pain syndrome unrelated to the site of surgery. Patients were evaluated for resolution of symptoms at two weeks, six weeks, three months, six months, and then at twelve-month intervals.

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Statistical Methods

The anesthesia information management system was used to analyze data. Paired Student t tests were performed with significance defined as p < 0.05 for further data analysis.

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Of the 568 consecutive patients who had shoulder surgery performed by the senior surgeon, 547 had complete anesthetic and orthopaedic records. The mean age (and standard deviation) of the patients was 53 ± 18.4 years (range, eight to 100 years). The mean weight was 79 ± 19.7 kg (range, 24 to 175 kg). Two hundred and ninety-five patients (54%) had arthroscopic shoulder surgery, and 252 patients (46%), including eighty who had a total shoulder arthroplasty, had open shoulder surgery (Fig. 1). Interscalene block alone was planned for 478 patients. General anesthesia was planned as the primary anesthetic agent for sixty-nine patients because of the expected length, complexity, or location of the procedure (i.e., posterior procedures or clavicular or sternoclavicular procedures medial to the blocked area and procedures requiring harvest of iliac crest bone or tensor fascia lata for grafting) or because of patient insistence (Fig. 2). Of the sixty-nine patients, thirty-four also received interscalene regional block prior to general anesthesia to aid in postoperative pain control. Of the 478 patients who were to have been managed with interscalene regional block alone, 462 (97%) had a successful block and sixteen (3%) had block failure requiring the conversion to general anesthesia. Overall, eighty-five patients received general anesthesia and 512 patients received an interscalene regional block.

Of the sixteen patients with a block failure, nine had an unsuccessful result because the interscalene regional block was not achieved and three had an incomplete block (see Appendix). In addition, two patients could not tolerate the block placement, and one patient could not tolerate the positioning and the length of the procedure and thus adjunctive general anesthesia was induced midway through the operation. In the remaining patient, local anesthetic tinged with blood was aspirated after injection of 20 mL of 1.5% mepivacaine. The patient exhibited no signs of central nervous system toxicity and had no signs of seizure activity during a five-minute period of observation, but the interscalene regional block was aborted and general anesthesia was induced.

Prior to the start of the surgical procedure, all 462 patients receiving interscalene regional block alone were given an additional field block averaging 7.7 mL of a mixture of 0.25% bupivacaine and 1% lidocaine with epinephrine. Of those patients, 397 received propofol at an average rate of 37.5 μg/kg/min and 455 received an average of 1.7 mg of midazolam. In addition, 319 of the 455 patients received an average of 44.5 μg of fentanyl during the procedure. For the sixty-nine patients managed with general anesthesia alone, the average dose of midazolam was 1.83 mg and the average dose of fentanyl was 360 μg.

For the patients who received interscalene regional block alone, the average procedure length was 157 minutes, the average anesthesia length was 211 minutes, and the average nonsurgical time was fifty-four minutes. For the patients managed with general anesthesia alone, the average procedure length was 174 minutes, the average anesthesia time was 255 minutes, and the average nonsurgical time was eighty-one minutes. This difference between nonsurgical times for interscalene regional block alone and general anesthesia alone was found to be significant (p < 0.02). With the numbers available, no difference was detected between procedure lengths when patients who had general anesthesia were compared with those who had an interscalene regional block (p = 0.09).

No patient had an acute complication; however, twelve (2.3%) of the 512 patients who received an interscalene regional block had a nonacute complication (Table I). All symptoms of the nonacute complications appeared within fourteen days after the surgical procedure and were reported by the patients at the two-week postoperative follow-up visit. Eight of the twelve complications occurred in patients who had open surgical procedures, whereas four developed in patients who had arthroscopy. Therefore, the complication rate was 1.4% for those receiving an interscalene regional block for arthroscopy and 3.2% for those who had open shoulder surgery. None of the patients had any clinical motor weakness. The most serious complication, complex regional pain syndrome, occurred in a patient who underwent a total shoulder arthroplasty to treat a chronic anterior shoulder dislocation. Exploration of the brachial plexus and isolation of the axillary nerve was required. In eleven patients, the symptoms spontaneously resolved by an average of nine weeks (range, two weeks to six months). Only one patient did not have complete resolution of the paresthesias in the ring and little fingers. The symptoms were mild enough that the patient did not want any additional investigation or treatment. One patient had transient facial numbness, which was thought to be due to the positioning of the face mask used to secure the head during the operation. There were no complications of general anesthesia.

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This study confirms the finding that interscalene regional block is an effective anesthetic technique for both arthroscopic and open surgical procedures of the shoulder. The rate of successful blocks was 97%, the rate of short-term complications was 2.3%, and no patient had permanent disabling neurologic sequelae or seizures. Thus, we think that the advantages of interscalene regional block far outweigh the disadvantages of the technique. We believe that the ability to have a successful regional anesthesia program requires commitment and depends upon cooperation between the surgeons and the anesthesiologists. We introduce our patients to the concept of the interscalene regional block at the office of the senior surgeon during the surgical scheduling visit, when the risks and benefits of the anesthetic options are discussed. If it is presented as an advantageous method that avoids airway manipulations and postoperative nausea and vomiting and offers postoperative analgesia, there is a high degree of patient acceptance. We explain that there will be light sedation during the block placement, which will continue, as the patient desires, intraoperatively. Our anesthesiology residents receive extensive training in interscalene regional block and are supervised by a cadre of attending anesthesiologists who are committed to the use of regional anesthesia. Surgeons, too, must understand the anatomic limitations of the block and the necessity to supplement blocks, and they should not consider this cooperative effort to be a sign of block failure.

Our findings are consistent with those in multiple other studies1-10, yet the orthopaedic literature continues to challenge the use of interscalene regional block. Many of these conflicting studies are from community hospitals rather than university-based hospitals11. In particular, Weber and Jain reported on a retrospective review of 218 patients who had had shoulder surgery under interscalene regional block at a free-standing surgery center and a community hospital11. They reported a block failure rate of 13% (twenty-eight patients) and a complication rate of 4% (eight patients). The complications in their study were more acute than those in our study and included four patients who had respiratory distress due to phrenic nerve injuries, one patient who had a grand mal seizure, one who had cardiovascular collapse, and two who had temporary nerve injuries that persisted at six weeks. Therefore, their reluctance to offer interscalene regional block is understandable. Although our complication rate was 2.3% (twelve of 512 patients), it consisted primarily of sensory neuropathies, which resolved by an average of nine weeks. In addition, our block failure rate was only 3% (sixteen of 478 patients).

Several studies have warned against the use of interscalene regional block because of a high complication rate11-13. The possible complications, including cardiac arrest, grand mal seizures, high spinal blocks, hematoma, pneumothorax, phrenic nerve palsy, and respiratory distress, and the rates of occurrence of these complications have been well described1,6,11,12,14-26. The experience of our anesthesia team may have contributed to our lower complication rate as they are dedicated to the concept of regional anesthesia and practice it on a daily basis. In addition, the anesthetic techniques they use have been continually refined to improve outcomes and reduce risks27-31.

Of our ten patients who had postoperative paresthesias, five had symptoms on the ulnar side. These complications could possibly have been due to the use of an arm holder and/or the positioning of the limb during surgery. The ulnar nerve is anatomically derived from the lower cervical roots and is blocked by the interscalene regional block only 40% of the time32. Ulnar neuropathies due to positioning are known to occur more frequently than median nerve symptoms, primarily because of the superficial path that the ulnar nerve takes near the elbow33,34.

Conflicting results have also been reported with regard to nonsurgical operating-room times for those receiving interscalene regional block compared with those managed with general anesthesia. We found, as have several others, that these times are less for those receiving an interscalene regional block1,3,4,35. The difference in the nonsurgical times for our patients managed with interscalene regional block and those who had general anesthesia was twenty-seven minutes. Although we did not examine recovery room times, several studies have described a shorter stay in the recovery room after interscalene regional block and our experience is that many of our patients who have an interscalene regional block do not even need this phase of the recovery process2,3,10,35.

One limitation of this retrospective study is that the intravenous sedation, which is necessary to ensure patient comfort in the sitting position for extended periods of time, was not standardized. Other investigators have considered the need for intravenous narcotics on arrival in the recovery room to be an indication of block failure11. However, the majority of these patients had both general anesthesia and an interscalene regional block. Thus, intraoperative identification of block failure was not possible. As the majority of our patients received interscalene regional block alone, block failure was immediately evident. Thus, administration of a combination of intravenous medications was performed to achieve relief of positional discomfort and any patient anxiety or restlessness. We believe that this is an adjunct to a successful block, not a solution for an unsuccessful block.

In conclusion, interscalene regional block can provide effective anesthesia for most types of shoulder surgery, including arthroplasty and fracture fixation. We showed that interscalene regional block, when administered by an anesthesiologist committed to and skilled in the technique, has a high degree of success and a low rate of complications.

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A table listing all block failures is available with the electronic versions of this article, on our web site at (go to the article citation and click on “Supplementary Material”) and on our quarterly CD-ROM (call our subscription department, at 781-449-9780, to order the CD-ROM). ▪

The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

Investigation performed at the Leni and Peter W. May Department of Orthopaedics, Mount Sinai Hospital, New York, NY

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