Anesthesia for Shoulder Arthroplasty
Uchenna O. Umeh, MD
Chrissy J. Cherenfant, MD
Each year, the number of both in-hospital and ambulatory shoulder surgeries continues to increase in the United States. Examples of some common shoulder procedures include anatomic and reverse total shoulder arthroplasty, hemiarthroplasty, and shoulder arthroscopy. Surgery is indicated for management for many conditions such as rotator cuff repair, fractures, impingement syndrome, instability, and degenerative arthritis. As the elderly population undergoes many of these procedures and our population continues to age and live longer, more patients undergo elective shoulder replacement surgery to improve their quality of life by alleviating pain and restoring function.1,2,3,4,5
A vital aspect of shoulder surgery is the anesthesia provided, as it may often impact a patient’s postoperative pain, opioid utilization, and clinical outcome. The anesthetic plan for each patient is individualized and determined by factors such as the medical history, duration of surgery, positioning, and body habitus.6,7 With the emergence of many anesthetic techniques, it is essential to evaluate the anesthetic options for shoulder surgery and the elements that influence the anesthesiologist’s decision on the preferred plan (VIDEO 9.1).
TYPES OF ANESTHESIA FOR SHOULDER SURGERY
Depending on the nature of the shoulder surgery, a patient may be awake, be sedated, or undergo general anesthesia (GA) with appropriate airway management. Often, the anesthesiologist’s initial decision is determining whether general or regional anesthesia will be the primary mode of anesthesia.7
GA encompasses amnesia, unconsciousness, analgesia, autonomic and sensory blockade of responses to noxious surgical stimulation, and immobilization or muscle relaxation. As a result, patients have decreased awareness and recall with simultaneously controlled autonomic reflexes such as breathing.8,9,10,11 Despite these advantages and its common use, GA has drawbacks. Some disadvantages include necessary airway management, greater effect on cardiac and pulmonary function, possible increased morbidity and mortality risk in patients with multiple medical comorbidities, and inadequate postoperative pain control. With the sole use of GA, without regional anesthesia, patients will likely require more opioids intraoperatively and postoperatively. They may also be subject to a variety of side effects such as nausea, vomiting, pruritus, and drowsiness.7 In addition, compared to regional anesthesia for shoulder surgeries, GA is associated with an increased likelihood of pulmonary complications, blood transfusions, intensive care unit transfers, longer stays in the postanesthesia care unit, and more readmissions for pain, sedation, nausea/vomiting, and other complications.7,12,13,14,15,16 GA for shoulder surgery in the beach chair position is associated with reductions in cerebral oxygenation and consequential higher risk of neurological damage.6,15 Due to the many benefits of regional anesthesia, many patients undergoing GA will also receive a peripheral nerve block, such as an interscalene block (ISB). Compared to GA alone, this combination of care has been associated with shorter extubation time, faster recovery, less analgesic consumption, and lower pain scores, heart rate, systolic blood pressure, and incidence of adverse events.7,17,18
Although regional anesthesia has many advantages, it is important to note that it may not be 100% successful, and conversion to GA may occur in the setting of inadequate analgesia.7 Nevertheless, regional anesthesia promotes postoperative recovery and allows for shoulder surgery with less or without the need for GA and less opioid use intraoperatively and postoperatively, which also decreases the potential for the associated risks. Regional anesthesia can also be used in conjunction with other forms of anesthesia for sedation, with the outcome of patients achieving optimal postoperative pain management, care, comfort, and satisfaction.6,7,19,20,21 Regional anesthesia suitable for shoulder arthroplasty encompasses peripheral nerve blocks such as interscalene nerve blocks, supraclavicular nerve blocks, suprascapular nerve blocks (SSNBs), and axillary nerve blocks. Anesthesia for shoulder surgeries may also include intra-articular local anesthesia injections.
PERIPHERAL NERVE BLOCKS
An interscalene nerve block or ISB covers most of the brachial plexus (C5-T1), upper and middle trunks, which supplies the upper extremity while sparing the ulnar nerve (C8-T1) (FIGURES 9.1 and 9.2). An ISB is composed of a local injection of 15 to 25 mL of a long-acting anesthetic such as bupivacaine or ropivacaine. The block may last for about 12 to 24 hours and results in anesthesia of the shoulder, distal clavicle, and proximal humerus. The interscalene groove is often identified with ultrasound visualization of the needle and vital structures such as the subclavian artery, first rib, anterior and middle scalene muscles, and nerve roots of the brachial plexus. The positioning of this block entails the patients with their head turned away from the side of the block while in a supine position. Palpation and identification of the sternal notch, clavicle, and heads of the sternocleidomastoid muscle are often used to discern the interscalene space. Although less utilized compared to ultrasound, nerve stimulation is another method used to locate a peripheral nerve or nerve plexus and facilitate the performance of a nerve block.6,7,19,22
Complications of an ISB are often due to needle or local anesthetic placement, including pneumothorax with an incidence of 0.2%, and blockade of the phrenic nerve that can cause transient ipsilateral hemiparesis of the diaphragm (78.75%-100%), which may lead to a 25% reduction in pulmonary function.6,22,23,24,25,26,27,28,29 Hoarseness may occur with an incidence of 3% to 31% as a result of recurrent laryngeal nerve blockade.24,27,30 Horner syndrome may result from blockage of the sympathetic trunk at an incidence of 1% to 59.6%, which is most likely an underestimation.23,25,27,29,31,32 Other rare complications include bleeding or hematoma formation, infection, vascular structure puncture, nerve damage, local anesthetic toxicity, or epidural or subarachnoid injection. Allergic reactions to local anesthesia are uncommon but also possible.6,22,23,24
ISBs can be done as a single-shot interscalene block (SSISB) with an injection of a local anesthetic or as a continuous interscalene block (CISB) by percutaneous insertion of a catheter adjacent to the brachial plexus. SSISB provides better analgesia, less nausea, and improved satisfaction than single-shot intra-articular injections or SSNBs.33 SSISB is also associated with less risk of neurological injury compared to CISB.34 However, some patients may benefit from greater analgesic coverage after surgery since SSISB has a limited duration. A CISB consists of an infusion of local anesthetic that allows prolonged analgesia and decreases opioid requirements.35,36,37,38 Compared to SSISB, CISB has been associated with a shorter length of stay; however, some studies have shown the contrary, with increased length of stay and increased barriers to discharge.39,40 Overall, an ISB is an effective anesthetic and analgesic technique that is commonly used for shoulder arthroplasty.
A supraclavicular block (FIGURE 9.3) is another anesthetic technique used for analgesia for shoulder arthroplasty. It rapidly blocks the brachial plexus at the nerve trunk level, which affects the distal two-thirds of the upper extremity such as the elbow, forearm, wrist, and hand. It can also block proximal nerves that supply the shoulder. However, there is concern that the nerves supplying the shoulder may be missed, depending on the anesthetic placement in the interscalene groove.7,23 The positioning for a supraclavicular block is similar to an ISB, with the addition of some preferring a 30° elevation of the head of the bed.41
FIGURE 9.2 Cross-sectional anatomy of the interscalene brachial plexus block. The brachial plexus is seen between the anterior and middle scalene muscles.
In the past, prior to widespread ultrasound use, there was reluctant utilization of the supraclavicular block due to the high incidence of pneumothorax. With ultrasound guidance, it is now known as a safe alternative to ISB that provides pain relief, with fewer potential side effects or complications like pneumothorax with an incidence of 0% to 6.1%.7,23,24,25,26,27,29,31,42,43 The possible complications of a supraclavicular block are similar to those of an ISB, including nerve injury, pneumothorax, vascular puncture, intravascular injection causing anesthetic toxicity, recurrent laryngeal nerve blockade, phrenic nerve blockade, and Horner syndrome.23,24,43,44 However, when compared to an ISB, studies have found supraclavicular blocks to have a greater motor blockade and reduced incidence of hoarseness (4.3%-22%), hemidiaphragmatic paresis (1%-65.2%), and Horner syndrome (1%-19.6%).23,24,25,26,27,29,31,43 Yet, it has not been found to be more efficacious than ISB for sensory blockade and pain control, where supraclavicular blocks compared to ISBs have not had any statistically significant difference in postoperative analgesia duration. Thus, a supraclavicular block is an effective option for anesthesia for shoulder arthroplasty.7,23,24,25,26,27,31,42