CHAPTER 4 Anesthesia, Patient Positioning, and Patient Preparation
This chapter reviews the anesthesia used for shoulder replacement surgery. Additionally, proper patient positioning and surgical preparation and draping are described.
ANESTHESIA *
Provided that no contraindication exists, all of our shoulder arthroplasty patients undergo a preoperative interscalene block administered in the preoperative holding area by an anesthesiologist. The interscalene block serves two purposes. First, use of the block minimizes the amount of general anesthetic needed during surgery, and second, it aids in postoperative pain management. Our anesthesiologists use a posterior approach and insert an indwelling brachial plexus catheter that is maintained for up to 48 hours after surgery (Fig. 4-1).1 General anesthesia, as well as neuromuscular paralytic agents, is then administered to all patients. Neuromuscular paralysis greatly facilitates exposure during glenoid resurfacing and can be discontinued after implantation of the glenoid component.
PATIENT POSITIONING
Proper patient positioning is crucial during shoulder arthroplasty. We use a standard operating table with the patient positioned sufficiently to the operative side to allow extension of the arm (Fig. 4-2). A rolled sheet is placed between the scapulae to slightly elevate the shoulder off the operating table and allow proper surgical preparation of the posterior aspect of the shoulder (Fig. 4-3). The use of certain types of operating tables developed for shoulder arthroscopy, in which the portion of the table posterior to the scapula is removed, is discouraged because these tables inhibit control of the scapula and thus make glenoid exposure difficult.
Figure 4-2 The patient is positioned sufficiently laterally on the operating table to allow full arm extension.
The patient is placed in the modified beach chair position. To obtain the proper position, the operating table is first reflexed (Fig. 4-4) and the patient’s knees are flexed (Fig. 4-5). The patient is then placed in a slight Trendelenburg position to prevent sliding inferiorly on the operating table (Fig. 4-6). Finally, the back of the operating table is elevated approximately 45 to 60 degrees relative to the floor (Fig. 4-7). The position of the patient’s head and neck is checked to ensure neutral alignment. Occasionally, it is necessary to slightly flex the head portion of the operating table to eliminate cervical extension. Once cervical alignment and the head position are acceptable, the forehead and chin are secured with 1-inch silk adhesive tape as shown in Figure 4-8. In patients with fragile skin, a dry gauze pad is used to minimize tape contact and prevent skin tears. Care should be taken to pad and protect bony prominences and sites of subcutaneous vulnerable nerves near the elbow (ulnar) and knee (peroneal). Figure 4-9 shows the final position of the patient before skin preparation.
