Fig. 25.1
The beach chair position for shoulder surgery
Surgery in the lateral decubitus position is not associated with a large hydrostatic gradient. Thus, the risk of iatrogenic lowering of blood pressure below critical thresholds is much lower. However, patients undergoing surgery in the lateral position may need a general anesthetic as regional anesthesia and sedation may not be sufficient for some patients to tolerate this position for prolonged periods. If the need to convert to general anesthesia arises, it can be difficult to secure the airway with the patient in the lateral position or even the beach chair position. The traction needed for surgery in the lateral decubitus position has been associated with injury to the brachial plexus, resulting in paresthesias and palsies. Ultimately, there is no objective, empirical evidence to support that one position is clearly superior to the other. It is the responsibility of the anesthesiologist to understand the risks and benefits associated with each position, and together with the surgeon, select the position safest for each patient.
Anesthetic Considerations
General anesthesia in addition to an interscalene block is the preferred anesthetic choice for most surgeons and anesthesiologists since the drapes often cover, or are near the patient’s face and airway. However, surgical anesthesia can be obtained with an interscalene block and intraoperative sedation in many cases. Selection of the local anesthetic used will determine onset time and duration of block and will differ for patients in which the block is performed for surgery itself versus postoperative analgesia. Other patients may require general anesthesia for poor cardiopulmonary reserve or other reasons (e.g., refusal of interscalene block). The decision to use a laryngeal mask airway (LMA) versus endotracheal tube (ETT) should be based on patient factors (e.g., presence of gastroesophageal reflux) as well as surgical factors (e.g., duration of surgery).
Postoperative Pain Management
After shoulder surgery, a number of different analgesic modalities are available. Traditionally, opioids and NSAIDs were used for postoperative pain, but caused a multitude of side effects. Infiltration techniques including subacromial (bursal) and suprascapular injections have been used, but a review of postoperative analgesia after shoulder surgery found that subacromial and intra-articular local anesthetic infiltration was only slightly better than placebo and intra-articular infusion has been linked to cases of catastrophic chondrolysis, thereby limiting its use. In patients undergoing shoulder arthroplasty, patients receiving regional analgesia (when compared to intravenous morphine PCA), had improved analgesia, earlier functional recovery on the first three postoperative days, less nausea and vomiting, and better sleep quality postoperatively. Additionally, patients undergoing rotator cuff repair with an interscalene block had less pain, were more likely to bypass the recovery room, and meet discharge criteria sooner than patients who underwent general anesthesia without the interscalene block. Although single-injection nerve blocks are adequate for short procedures and short-term postoperative analgesia, they are inadequate for prolonged postoperative analgesia. Continuous interscalene blocks may be performed when more than 24 h of analgesia is desired. Patients could then be discharged home with specific instructions to manage and discontinue the catheter.
Surgery on the Hand, Wrist, Arm, and Elbow
Orthopedic surgery of the upper extremity ranges from carpal tunnel release and trigger finger release to humerus fracture fixation. Many patients undergoing surgery of the upper extremity are good candidates for ambulatory surgery. Patients undergoing trigger finger release and carpal tunnel release can undergo local or regional anesthesia with minimal intraoperative sedation and be discharged home soon after surgery. For short procedures with minimal postoperative pain, local infiltration with intraoperative sedation may be an appropriate choice. The dogma that epinephrine should not be injected into the digits has been recently challenged. Most of the case reports of digital ischemia with local anesthetics occurred with cocaine or prilocaine, which have been known to cause digital ischemia even without epinephrine additives. There have been no case reports of digital ischemia with commercial preparations of lidocaine with epinephrine. Thus, small amounts of local anesthetics with diluted epinephrine (1:20,000 or less) are probably safe for digital infiltration or blocks.
More extensive surgery of the upper extremity involving bones and tendons may necessitate a regional and/or general anesthetic but can be accomplished in the ambulatory setting. Peripheral nerve blocks of the brachial plexus for upper extremity surgery include interscalene, supraclavicular, infraclavicular, and axillary blocks. Comparing the relative merits of regional techniques over general anesthesia alone, patients receiving a block had a faster recovery and discharge, fewer adverse events, and better postoperative analgesia. Improvements in ultrasound technology have greatly facilitated placement of upper extremity blocks. Given the close proximity of structures such as adjacent nerves (the phrenic nerve), major vasculature (carotid, subclavian, and axillary artery), and lung apex, ultrasound can be of great utility when performing blocks. Advantages of ultrasound guidance include direct visualization of anatomic structures, detection of anatomic variants, decreased incidence of vascular puncture, and usage of smaller volumes of local anesthetic. Furthermore, ultrasound-guided peripheral nerve blocks have been shown to have shorter performance times, faster onset time, and greater block success rates when compared to other methods of nerve localization.
An anesthetic technique frequently used for hand and forearm surgery is the intravenous regional block (IVRB) or Bier block (Fig. 25.2), named after August Karl Gustav Bier, who first described the block in 1908 (see chapter on peripheral nerve blocks). Advantages of Bier block include ease of administration, rapid onset (usually within 5 min), muscular relaxation, and rapidity of recovery. Disadvantages require need for special equipment (Esmarch bandages, double cuff tourniquet) and finite duration of anesthesia and lack of postoperative analgesia. Procedures that last more than 1 h should not be performed under Bier block. Serious complications including seizures, cardiac arrest, and compartment syndrome have been reported with use of Bier blocks.
Fig. 25.2
Intravenous regional block
Lower Extremity Surgery
Patients who come in for lower extremity procedures span a wide spectrum, from healthy athletes necessitating ACL repairs to elderly patients with multiple comorbidities necessitating emergent hip fracture surgery. Total knee and hip arthroplasties comprise a large percentage of surgeries performed on the lower extremities. As the population ages, more procedures will be performed on patients who have significant cardiac, pulmonary, renal, and hepatic diseases. In a prospective study of over 10,000 patients undergoing elective primary total hip or knee arthroplasty, the incidence of serious adverse events including myocardial infarction, pulmonary embolism, deep venous thrombosis, and death was 2.2 %. Most of the events increased in frequency with older age, especially in patients 70 and older. These risks, in addition to other anesthetic risks, must be discussed with patients preoperatively and all comorbid conditions should be optimized prior to elective procedures.
Surgery on the Knee
Knee Arthroscopy
Knee arthroscopy is commonly used to perform minor procedures on the patella, ligaments, or meniscus or to investigate for pathology that may be amenable to surgery at a later time. Preoperative discussion with the surgeon will enable the anesthesiologist to judge what degree of intraoperative and postoperative pain management will be necessary. For many patients undergoing simple arthroscopy, general anesthesia is the anesthetic of choice. In these patients, postoperative pain can be adequately managed with oral pain medications. For other patients who undergo knee arthroscopy combined with more extensive procedures, femoral and/or sciatic nerve blocks with long-acting local anesthetics may be necessary for adequate postoperative pain control.
Knee ACL Repair
Injury to the anterior cruciate ligament (ACL) is the most common ligamentous injury of the knee, which frequently occurs in young adults as a result of sports-related injuries. ACL repairs are generally performed arthroscopically as outpatient procedures, which have been associated with lower complication rates, lower costs, and higher patient satisfaction. The ideal anesthetic for outpatient ACL repair should be highly effective, relatively inexpensive, and have few side effects, enabling patients to return home shortly after surgery. ACL reconstruction can be performed under general or spinal anesthesia, with postoperative analgesia provided with a single shot or continuous femoral nerve block (which are usually performed preoperatively). Often, patients who have a successful femoral block may complain of posterior knee pain in the recovery room and may need a “rescue” sciatic block. This is more likely when hamstring autografts are used. Ideally, a preoperative femoral and a sciatic block will yield a prolonged pain-free postoperative course.
Total Knee Arthroplasty
Total knee arthroplasty (TKA) is one of the most commonly performed procedures in orthopedic surgery. Most patients have osteoarthritis or rheumatoid arthritis of one or both knees. Pain after TKA is substantial and can last many days following surgery. Therefore, adequate pain control postoperatively is paramount to facilitation of early ambulation, which decreases the incidence of thromboembolic disease. Furthermore, improved pain control allows for earlier commencement of physiotherapy, which has been shown to improve recovery. Anesthetic techniques for surgery include neuraxial blockade (e.g., spinal or epidural) and general anesthesia. Postoperative analgesia can be managed with intravenous, intrathecal/oral opioids, neuraxial blockade, peripheral nerve blockade, and local infiltration analgesia.
Choice of Anesthesia
Total knee arthroplasty is frequently performed under neuraxial anesthesia with intraoperative sedation. Spinals are commonly used and are advantageous because they do not involve an indwelling (epidural) catheter, but only last for a finite time period and thus may not be suitable for redo operations. Epidurals can be used for surgery, but are contraindicated in patients receiving high-dose low molecular weight heparin (risk of epidural hematoma). Therefore, use of epidurals for postoperative analgesia is somewhat limited in this population of patients who are at high risk of postoperative thromboembolic disease and are anticoagulated postoperatively. However, hemodynamic effects with epidurals are generally more gradual and thus easier to treat than with spinal anesthesia. In addition, the duration of an epidural is not limited as it is with a spinal and thus may be useful for reoperation or bilateral TKAs or if surgery becomes longer than anticipated. The epidural catheter can be removed immediately after surgery or prior to the commencement of anticoagulation. Recommendations for withholding anticoagulation prior to removal of the epidural are discussed in the section on thromboprophylaxis.
New microsomal technology now allows the delivery of a single dose of extended-release morphine into the epidural space to be released over 48 h. In one study, patients who underwent TKA who received extended-release epidural morphine versus a sham epidural had significantly lower pain scores and opioid consumption. Thus, this technique allows for prolonged analgesia while circumventing the increased risk of postoperative epidural hematoma associated with indwelling catheters. Patient selection is important, however, as an increased risk of delayed respiratory depression can be seen with extended-release epidural morphine.
Postoperative Pain Management
Management of postoperative pain following TKA is important as adequate pain control allows for faster rehabilitation and reduces the risk of postoperative complications such as joint adhesions. Conventional pain management after TKA relied on administering intravenous and oral opioids postoperatively. Patient-controlled analgesia (PCA) proved to be superior when compared to traditional nurse-administered analgesia in terms of quality of pain control and patient satisfaction, but many patients still experienced a significant amount of pain. More recently, newer approaches to pain management have focused on a multimodal approach and preemptive analgesia. The goal in preemptive analgesia is to limit the sensitization of the nervous system to painful stimuli, thus decreasing the amount of noxious stimuli that reaches the spinal cord and brain from the peripheral nervous system. Multimodal approaches to analgesia focus on using multiple agents to decrease the side effects of each while maximizing synergism amongst different classes of medications. Local infiltration analgesia (LIA) has increased in popularity over the past 5–10 years. LIA usually consists of injection of a long-acting local anesthetic (e.g., ropivacaine), a nonsteroidal anti-inflammatory drug (e.g., ketorolac), and epinephrine through a catheter placed in the knee.
Femoral nerve blocks are frequently utilized for management of postoperative pain in patients undergoing TKA. Placement can be guided by nerve stimulation and/or ultrasound. Both single-shot techniques and continuous techniques utilizing indwelling catheters are used. With continuous techniques, dilute solutions of local anesthetic can be infused using traditional pumps. Unlike epidurals, femoral nerve catheters are not contraindicated when thromboprophylaxis with high-dose low molecular weight heparin is started postoperatively. Femoral nerve blocks reduce PCA morphine consumption, pain scores with activity, and incidence of nausea when compared to intravenous PCA only. Traditionally, patients could only receive continuous perineural infusions as inpatients. However, with the advent of portable infusion pumps, ambulatory continuous peripheral infusions became possible, allowing patients the advantage of prolonged analgesia without increasing the length of hospitalization.
Despite the numerous advantages that femoral nerve catheters offer, there is ongoing concern about associated quadriceps weakness. It has been estimated that prolonged quadriceps weakness occurs in 2 % of patients with femoral nerve blocks. Patients with quadriceps femoris weakness are predisposed to falls, fractures, and decreased ability to participate in physiotherapy, which could increase the length of hospitalization. The goal in selecting a local anesthetic and concentration is to maximize the sensory block while minimizing the degree of motor block. One study comparing continuous femoral nerve blocks with equal local anesthetic mass of ropivacaine 0.1 % versus 0.4 % found the same incidence of weakness in both groups and concluded that total local anesthetic dose (mass) is the primary determinant of perineural infusion effects, rather than concentration and volume.
As more studies are done to improve the intraoperative and postoperative management of TKA patients, anesthesiologists will have more tools in their armamentarium. Nowadays, it is not uncommon for a patient undergoing TKA to have a femoral nerve catheter inserted preoperatively, undergo a spinal (or epidural) anesthetic with sedation for the surgery itself, and have postoperative pain control with a dilute infusion of local anesthetic through the femoral nerve catheter. Femoral nerve catheters can then be weaned and discontinued on postoperative day 2 or 3 as the patient is transitioned to systemic medications. Alternatively, ambulatory continuous femoral nerve infusions may be continued after discharge from the hospital with instructions for self-removal at a later time, thus allowing continued benefit from the femoral nerve catheter and avoidance of systemic medications and side effects. Determination of the optimal local anesthetic, concentration, and dose may improve the safety of continuous femoral nerve block in the future.
Surgery on the Hip
Arthroscopy
Arthroscopy of the hip is being performed more frequently, both as a diagnostic and therapeutic tool. It is used to treat many conditions including loose bodies, labral tears, synovial disorders, articular injuries, adhesive capsulitis, and femoroacetabular impingement. Many patients are athletes who are otherwise healthy, while others may be elderly with multiple comorbidities and a history of previous hip surgeries. In many circumstance, hip arthroscopy is an ambulatory procedure. For patients who have more extensive surgical manipulation or comorbidities, an overnight stay may be required. Some of these patients may have chronic hip pain and be opioid dependent, making postoperative analgesia more challenging. Neuraxial and peripheral nerve blocks may be especially advantageous in these patients with varying degrees of opioid tolerance.
General anesthesia is commonly used for the procedure as neuromuscular relaxation allows for optimal joint distraction. In addition, the airway may be difficult to secure if an untoward event occurs in the lateral decubitus position. Pain after hip arthroscopy can range from mild to severe depending on the amount of surgical manipulation intraoperatively. Despite the use of intraarticular bupivacaine at the conclusion of surgery, many patients have considerable postoperative pain and require rescue analgesics in the recovery room. However, increasing amounts of opioids can lead to significant adverse effects such as nausea and vomiting, urinary retention, and respiratory depression which may necessitate overnight admission. Paravertebral L1 and L2 blocks may provide sufficient postoperative analgesia following arthroscopy while sparing quadriceps strength, thus facilitating earlier postoperative ambulation. A femoral nerve block may also provide analgesia in some patients.
Hip Fracture Surgery
Hip fractures commonly affect the elderly and are a major cause of morbidity and mortality in the aging population. One-year mortality rates after hip fractures range from 14 to 36 %, increasing with patient age and comorbidities. Patients with hip fractures frequently have multiple medical comorbidities that can significantly increase perioperative risk. Conditions such as infection, anemia, dehydration, electrolyte imbalance, and altered mental status are frequently seen in patients with hip fractures. The need for further workup and optimization of medical status must be balanced with minimizing the time before surgery, which can decrease morbidity. Anesthetic management must be thoughtfully tailored to each patient to ensure adequate analgesia while minimizing the risk for cardiac and pulmonary complications, as well as postoperative cognitive dysfunction.
For femoral neck fractures, fracture displacement is a major consideration in deciding which type of surgical fixation is appropriate. In patients under 65 years of age, non-displaced intracapsular fractures are stabilized with percutaneous screws or pins, whereas displaced intracapsular fractures are typically treated by open reduction and internal fixation (ORIF). In patients over 65 years of age with femoral neck fractures, hemiarthroplasty and total hip arthroplasty are usually performed. Intertrochanteric and subtrochanteric fractures are usually stabilized using an intramedullary nail or sliding hip screw and a plate device.
Anesthesia for hip fracture surgery can be achieved through neuraxial techniques (e.g., spinal or epidural) or general anesthesia. There is lack of scientific data demonstrating that one anesthetic technique is clearly superior. However, regional anesthesia may offer a slight benefit over general anesthesia in reducing acute postoperative confusion in patients undergoing hip fracture surgery. Positioning patients with hip fractures for epidural or spinal placement can be challenging. Patients with dementia or delirium may have difficulty with positioning and remaining still. Many patients will not be able to tolerate the sitting position. Furthermore, these patients usually cannot bear weight on the broken hip but may be able to be positioned in the lateral decubitus position with the operative hip up.
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