Orthopedic patients can be challenging for the anesthesiologists, especially shoulder surgeries. These patients represent a wide spectrum of medical problems, ranging from an elderly patient with various comorbidities to a young healthy trauma patient with multiple associated injuries that should be taken into consideration when administering anesthesia to these patients.

This chapter discusses the preoperative evaluation that is essential for the preparation of the patient undergoing shoulder surgery; a discussion of the anesthetic choices and why they are selected for this type of surgeries; and also a description of the various regional anesthetic blocks including the home going brachial plexus catheters. We focus on the postoperative pain management techniques as we believe that they are a vital component to the management of shoulder surgery patients.

The goals of preoperative evaluation are to reduce patient risk, morbidity of surgery, as well as to promote efficiency, reduce costs and cancellation rates, and increase resource utilization in the operating room. The anesthesiologist’s preoperative
evaluation is crucial to the formulation of the anesthetic plan. With the increasing severity of coexisting medical illness in patients undergoing shoulder surgeries, the anesthesia team is required to evaluate and optimize the patient’s health status. The patient must be evaluated by an anesthesiologist before the surgery date ideally in the preoperative evaluation clinic. This preoperative evaluation should include previous anesthetic complications, allergies, list of medications including over-the-counter and herbal products, potential airway difficulties, and preexisting medical problems that need optimization before the surgery. Information technology has helped the anesthesiologist in previewing the upcoming patients who will be anesthetized. This visit to the preoperative evaluation clinic also provides a great opportunity for the anesthesiologists to obtain an informed consent from the patient and discuss the anesthetic plan including invasive monitoring, regional blocks, and what medications the patient needs to continue during the perioperative period. This preoperative evaluation, coupled with understanding the surgeon’s needs, is used to formulate the anesthetic plan including perioperative pain management. Finally, psychological preparation of the patient for the upcoming surgery is very important and usually starts during the preoperative visit of the patient to the surgery clinic and the anesthesia evaluation clinic.

The American Society of Anesthesiologists (ASA) physical status is used by all anesthesiologists to evaluate all surgical patients. Patients classified as ASA physical status 1 to 2 may be evaluated on the morning of the surgery. To avoid surgical delays and to optimize the patient’s medical conditions, patients classified as ASA status 3 or higher should be evaluated sooner or ideally in the preoperative assessment anesthesia clinic where consults can be ordered and seen in a timely and efficient manner.

The ASA Physical Status Classification System

ASA Physical Status 1—A normal healthy patient

ASA Physical Status 2—A patient with mild to moderate systemic disease; examples: bronchial asthma, hypertension, and diabetes mellitus

ASA Physical Status 3—A patient with severe systemic disease that limits his activity but it is not incapacitating; examples: poorly controlled hypertension, uncontrolled diabetes mellitus with vascular complications and heart disease that limits activity

ASA Physical Status 4—A patient with severe systemic disease that is a constant threat to life; examples: advanced pulmonary, hepatic, or renal dysfunction and heart failure

ASA Physical Status 5—A moribund patient who is not expected to survive for 24 hours with or without an operation; examples: ruptured aortic aneurysm, pulmonary embolus.

If the surgery is claimed to be emergency by the surgeon then the ASA number is preceded with an E.

Preoperative laboratory tests should be ordered only based on defined indications such as positive findings on history and physical examination. For example, if the patient is taking Coumadin, his prothrombin time should be checked despite that the patient had stopped taking the medication for 5 days. The rate of detection of real medical problems by routine screening tests is extremely low by comparison to the cost of these tests and the number of patients undergoing unnecessary further workup. Routine screening, especially in young patients, of blood counts, electrolytes, and chest radiograms is probably not reasonable without indication, such as age, disease state as diabetes mellitus, and medications as diuretic.

In this chapter, we describe the common medical conditions that influence the patients undergoing shoulder surgeries and discuss how they are evaluated and optimized prior to surgery.

Rheumatoid arthritis (RA) is a chronic inflammatory form of arthritis which affects about 1% of adults, with prevalence two to three times higher in women than in men. RA is characterized by persistent joint synovial tissue inflammation leading to bone erosion, destruction of cartilage, and loss of joint integrity.²⁴ RA is characterized by morning stiffness often lasting more than 1 hour after initiating activity. It often progresses through multiple exacerbations and remissions, and 20% to 30% of the affected individuals become permanently disabled within 3 years of diagnosis. Morning stiffness and involvement of the wrists and metacarpophalangeal joints helps distinguish RA from osteoarthritis, which typically affects weight-bearing joints and the distal interphalangeal joints. Because of the multiple systemic problems associated with RA and the side effects of the medications administered to treat RA, there are multiple anesthetic considerations. Synovitis of the temporomandibular joint may significantly limit mandibular motion and mouth opening in these patients. Arthritic damage to the cricoarytenoid joints may result in diminished movement of the vocal cords, resulting in a narrowed glottic opening; this is manifested preoperatively as hoarseness and stridor. During laryngoscopy, the vocal cords may appear erythematous and edematous, and the reduced glottic opening may interfere with the passage of the endotracheal tube (ETT).⁷⁴ There is also an increased risk of cricoarytenoid dislocation with traumatic endotracheal intubations.

Arthritis of the cervical spine is common in patients with RA. Anterior sublaxation of C1 on C2 (atlanto-axial sublaxation) may occur in 40% of the patients with RA, with symptoms of progressive neck pain, headaches, and myelopathy. Posterior and vertical migration of the odontoid process is less common. Flexion of the head in the presence of atlantoaxial instability could result in the displacement of the odontoid process into the cervical spine and medulla leading to the compression of the vertebral arteries. This may precipitate quadriparesis, spinal shock, and death. Preoperative cervical flexion-extension radiographs should be evaluated in RA patients with limited neck movement and neurologic symptoms. If the distance from the anterior arch of the atlas to the odontoid process exceeds 3 mm, the patient should undergo an awake fiberoptic tracheal intubation, and the cervical spine should be protected with a cervical collar during the procedure.⁵¹

The incidence of silent C-spine instability is not rare. Some centers will require flexion-extension films for elective surgery. If intubation cannot be performed without spine manipulation, either X-ray evaluation or awake fiberoptic tracheal intubation would be indicated. In cases of extreme instability, even awake intubation itself may not be totally
safe, and prior mechanical stabilization of the neck such as the halo device may be necessary. Emergency airway management requires manual in-line stabilization of the neck.

Many of the systemic manifestations of RA are most likely consequences of vasculitis due to deposition of immune complexes on the walls of small vessels with subsequent inflammatory reactions. RA can lead to destruction of the pulmonary parenchyma leading to restrictive pulmonary disease. In the cardiovascular system, pericardial thickening or effusion as determined by echocardiography is present in about 33% of the patients with RA. A large pericardial effusion can exist with minimal symptoms and create unexpected tamponade physiology under anesthesia. RA patients with limited physical activity should have echocardiography before an elective surgery to evaluate the extent of pericardial effusion and cardiac valve involvement. Rheumatoid patients on chronic steroid therapy may have extremely thin skin with reduced tensile strength, which is easily injured with the removal of adhesive tape or minor pressure. To avoid skin injury, we use skin barriers and bed surfaces should be padded to decrease pressure on the fragile skin of the patient. Patients on chronic steroid therapy should receive full-dose steroids to avoid adrenal suppression.

Hypertension is defined as systolic/diastolic blood pressures of 140/90 mmHg or more on at least two occasions measured at least one to 2 weeks apart.⁷¹ Hypertension is the most common circulatory derangement in the United States, affecting approximately 24% of adults. The incidence of hypertension increases with age, and the risk of systemic hypertension is higher in the African-American population.⁷² Systemic hypertension is a significant risk factor for the development of ischemic heart disease and is a major cause of congestive heart failure, cerebral vascular accident, arterial aneurysm, and endstage renal disease.

Poorly controlled hypertensive patients have more intraoperative hemodynamic instability, and it may limit the ability of the anesthesiologist to safely decrease the blood pressure to the surgeon’s desired limit during the surgical procedure. Hypertensive patients tend to have better perioperative care if their blood pressure was controlled prior to anesthesia. The anesthesiologists should avoid the addition of epinephrine to the local anesthetic solution utilized for regional anesthesia blockade. Hypertensive patients should be instructed to continue their antihypertensive medications during the perioperative period including the morning of the surgery except for angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers and diuretics. Placement of an arterial line catheter should be considered by the anesthesiologist in patients with uncontrolled blood pressure in the emergency setting to properly titrate the antihypertensive medications, and avoid wide swings in blood pressure.

There is controversy regarding a trigger to delay or cancel a surgical procedure in a patient with untreated or inadequately treated hypertension. Although there has been a suggestion in the literature that a case should be delayed if the diastolic pressure is greater than 110 mmHg, the study often quoted as the basis for this determination demonstrated no major morbidity in that small group of patients.²⁹ However, such patients are prone to perioperative myocardial ischemia, ventricular dysrhythmias, and lability in blood pressure. The risk of anesthesia and surgery is less clear in patients with blood pressures above 180/100 mmHg, although no absolute evidence exists that postponing surgery will reduce risk.³⁵ In the absence of end-organ changes, such as renal insufficiency or left ventricular hypertrophy with strain, it would seem appropriate to proceed with surgery. In contrast, a patient with a markedly elevated blood pressure and new onset of a headache should have surgery delayed for further management.

The benefit of preoperative screening is to identify those patients requiring further diagnostic evaluation. Patients at risk for silent myocardial ischemia such as diabetics may present an indication for more aggressive diagnostic testing prior to elective orthopedic surgery. The electrocardiogram (ECG) is used as a screening test in patients with cardiac risk factors such as hypertension and diabetes mellitus. The ECG should be compared to a prior tracing to detect new ST segment changes, Q waves, and new arrhythmias that need further evaluation prior to elective surgery. Elective surgery for a patient with new left bundle branch block or new atrial fibrillation should be postponed till the patient is evaluated by a cardiologist. If the patient’s medical history indicates that a stress test is needed, then depending on the patient’s functional status, a decision for a exercise stress test or pharmacological stress test (such as echocardiographic Dobutamine stress test or Persantine thallium or reperfusion imaging) should be taken. Stress echocardiography would give valuable information about left ventricular function (ejection fraction), any regional wall motion abnormality indicative of ischemia, and the function of the major cardiac valves which is important in the planning of the anesthesia for these patients. If the patient had a positive stress testing, then cardiac catheterization would reveal the degree of stenosis in the coronary vessels. Undetected severe coronary artery stenosis can lead to perioperative myocardial infarction, congestive heart failure, or sudden death.

The American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend preoperative cardiac testing in patients at increased cardiac risk on the basis of clinical risk profile, functional capacity, and type of surgery.²¹ The ACC/AHA classifies orthopedic surgery as intermediate risk surgery, which in most cases involves intermediate-risk patients. Data for orthopedic surgery showing that preoperative risk stratification or coronary revascularization, or both, having an effect on outcomes, are limited. However, a report by Salerno et al. suggested that preoperative abnormal noninvasive cardiac testing rarely changed medical management before orthopedic surgery.⁶¹ The Decrease-II study questioned the value of preoperative cardiac testing in patients at intermediate risk before non cardiac surgery.⁵⁷ In the CASS registry, Eagle et al. reported that coronary artery bypass graft surgery offered no advantage before orthopedic surgery in reducing cardiac mortality.²² Postoperative myocardial infarction and death have not been reduced for noncardiac surgery in patients at cardiac risk when preceded by percutaneous coronary intervention as well.⁷⁵ Patients in whom percutaneous coronary intervention involve the placement of stents carry the added
risks of restenosis and thrombosis if anti-platelet therapy has to be discontinued before surgery, and increased perioperative bleeding if these medications are continued through the perioperative period.⁹

If the data suggest that preoperative cardiac testing and revascularization do not decrease postoperative cardiac morbidity, hemodynamic stress reduction might be the answer. Numerous studies have indicated that the use of perioperative adrenergic B-blockers can reduce myocardial ischemia and postoperative myocardial infarctions.⁷³ In elderly patients undergoing shoulder surgeries, B-blockers should be continued perioperatively in the patients taking long-term B-blockers and initiated in the patients at the highest risk, with a target heart rate less than 80 beats/minute.²⁵

Valvular heart disease places a hemodynamic burden on the left and/or right ventricle that is initially tolerated as the cardiovascular system compensates for the overload. Hemodynamic overload eventually leads to cardiac muscle dysfunction, congestive heart failure, and sometimes sudden death.¹² The preoperative evaluation of the patient with valvular cardiac disease will be the same as that of coronary artery disease, in addition to quantifying the degree of the valvular lesion. This is particularly important in stenotic lesions such as aortic and mitral stenosis. The combination of aortic stenosis and coronary artery disease is common and needs careful monitoring and anesthetic planning during the perioperative period. Most valvular lesions induce hypertrophy of the myocardium in response to increased work, so it is important to evaluate the function of the left ventricle. Management of the patient with valvular heart disease during the perioperative period requires an understanding of the hemodynamic alterations that accompany dysfunction of the cardiac valves. The most frequently encountered cardiac valve lesions produce pressure overloads (mitral stenosis, aortic stenosis) or volume overloads (mitral regurgitation, aortic regurgitation) on the left atrium or left ventricle.

Preoperative evaluation of orthopedic patients with pulmonary disease is important to identify correctable problems that could lead to pulmonary complications in the perioperative period. Chronic obstructive pulmonary disease (COPD) is characterized by the progressive development of airflow limitation that is not fully reversible.⁴ The term COPD encompasses chronic obstructive bronchitis (with obstruction of small airways) and emphysema (with enlargement of air spaces, destruction of lung parenchyma, loss of lung elasticity, and closure of small airways). Most patients with COPD have chronic obstructive bronchitis, emphysema, and mucous plugging with variable degrees. Chronic bronchitis and emphysema are distinguished from asthma in that the abnormalities causing chronic bronchitis and emphysema are usually irreversible.

Orthopedic patients with pulmonary disease should be optimally prepared for elective surgery. The goal of preoperative evaluation is to treat active infections, maximum treatment of bronchospasm with bronchodilators and steroids, facilitation of sputum clearance, cessation of smoking, and treatment of any serious non-pulmonary sequelae of pulmonary disease. If steroid therapy is required, then it is mandatory to continue steroid therapy through the perioperative period. The evaluation of the severity of pulmonary disease includes chest X-ray, arterial blood gas analysis, room air saturation, and pulmonary function testing. Diffusion capacity and carbon monoxide (DLCO) studies helps to distinguish between fixed lesions (decreased DLCO) and bronchospastic disease (normal DLCO). If the forced expiratory volume/functional residual capacity ratio is less than 40% or if there is a 40% or greater reduction in the diffusion capacity, then the morbidity in the perioperative period greatly increases.

Achondroplasia is the most common cause of dwarfism, with short stature, short trunk, and disproportionate development. Usually affected individuals are of normal intelligence and can live a full and productive life. Their associated medical problems often require orthopedic surgical intervention.³¹ Premature fusion of the base of the skull resulting in a narrowed cervical canal or foramen magnum stenosis or both is the most serious complication of achondroplasia. Direct laryngoscopy and tracheal intubation can be difficult and dangerous in achondroplastic dwarfs. Also, neck flexion should be avoided in dwarfs with atlanto-axial instability or foramen magnum stenosis. Awake fiberoptic tracheal intubation is the safest method to secure the airway in these patients; awake tracheostomy is another alternative if awake fiberoptic intubation is difficult or not feasible due to non-cooperative patients or other contraindications.

Dwarfs can represent another anesthetic challenge to the anesthesiologist because of restrictive lung disease and pulmonary hypertension. Pulmonary hypertension develops from chronic hypoxemia and hypercarbia secondary to airway obstruction, sleep apnea, and thoracic kyphoscoliosis. Preoperative spirometry can be difficult to interpret in a dwarf.⁶⁸ An echocardiogram should be obtained before elective surgeries to assess the degree of pulmonary hypertension and intra-cardiac shunts. In these patients, the anesthesiologists should avoid factors that can aggravate pulmonary hypertension such as hypoxemia, acidosis, hypercarbia, hypothermia, and ensure adequate cardiac output and end-organ perfusion.

Patients with severe pulmonary, cardiovascular, or other serious medical conditions are considered high-risk patients for having anesthesia. The severity of the medical illness can be risky enough (e.g., a patient with critical aortic stenosis with aortic valve area 0.5 cm) to the extent that it would not be reasonable to proceed with elective surgery due to the high anesthetic risks and postoperative risks.

However, some of the high-risk patients seek shoulder joint replacement surgeries despite their severe medical issues. In such a situation, the goal of the anesthesiologist is to make sure that the patient, surgeon, medical specialist caring for
the patient, pertinent family members involved in postoperative care, all have the same understanding of the perioperative risks of the surgery and anesthesia. Also, all correctable and reversible conditions should be treated and the patient’s medical conditions should be optimally prepared before proceeding with elective surgery. The preoperative planning must include informed consent, and the patient must be aware of what specific risks he or she is accepting. Documentation must be explicit and detailed prior to the anesthetic intervention.

Regional anesthesia, though carries less risk than the routine general anesthesia and airway instrumentation, should not be considered a safe alternative for patients with a high-risk medical condition. Regional anesthesia induces less stress on the cardiovascular system and minimize the amount of anesthetics needed, avoiding their side effects. The patient should be presented with the fact that regional anesthesia for surgical procedure can always proceed to general anesthesia at different stages of surgery for several reasons, mainly failure or partial block, development of side effects or systemic toxicity of local anesthetics, and prolonged or extended surgery. Moreover, most perioperative cardiac mortality and morbidities occur in the first 48 hours after surgery. The same degree of invasive monitors and precautions should be applied to patients with high-risk medical conditions irrespective of whether the surgery is performed under regional anesthesia or general anesthesia.

Intraoperative anesthetic management is considered the critical part of the whole perioperative anesthetic course. It should be discussed with the patient preoperatively in the context of whole anesthetic and pain management plan.

As every patient has different potential risks for one or more of the anesthetic options, the plan should be individualized for each patient.

The anesthetic and pain management plan is formulated on an individual basis within certain guidelines that need to be discussed with each patient preoperatively. There are some points that should be considered before proceeding with each case that could potentially change the management plan, mainly:

For major shoulder surgeries (e.g., revision shoulder arthroplasty or tumor excision), type and screen, or type and cross need to be current before proceeding with surgery.

Intraoperative monitoring should include an ECG, temperature monitoring, automated noninvasive blood pressure monitor, end-tidal CO₂ detector and a pulse oximeter (i.e., American Society of Anesthesiology Standard for Basic Monitoring). Although not mandatory with regional anesthesia, continuous monitoring of expired carbon dioxide (with a split nasal cannula) is an early and sensitive indicator of ventilatory changes. This is essential for patients receiving regional anesthesia supplemented with sedation to avoid potentially disastrous outcomes.³²

The decision to use invasive monitoring is usually based on two main factors—patient comorbidities and the extensive nature of the surgery.

Patients who are susceptible to significant hemodynamic changes such as those with advanced heart disease or sepsis may benefit from tight blood pressure management using arterial line to guide fluid/pressor therapy. As mentioned before, the sitting position is associated with pooling of blood to the lower half of the body, decreasing venous return, and challenging the cardiovascular system to compensate and maintain the blood pressure. Patients with limited reserve will benefit from invasive monitors to quickly titrate fluid and pressor therapies.

Intraoperative fluid management can arguably be better guided in sick patients using central venous catheters. Central venous pressure reflects the filling pressure of the right-hand side of the heart which might not correlate well with the left-hand side of the heart. Pulmonary artery capillary wedge pressure on the other hand is a more reliable monitor for the left-hand side of the heart when indicated. The central venous catheter gives a reliable access for rapid transfusion and is the preferred route for pressor administration due to its proximity to the heart.

In certain conditions, with severe valvular diseases or stiff myocardium, where the right-sided pressure does not reflect the volume status of the left ventricle, it may be prudent to have intraoperative transesophageal echocardiogram. It allows direct visualization of the filling volume for the right and left ventricles, contractility function of the ventricle (ejection fraction), as well as valvular functions.

Intraoperative fluid management varies according to the type of surgery and the patient comorbidities. Although liberal fluid management might improve renal perfusion and urine output, it could be poorly tolerated in patients with severe systolic dysfunction. Patients with significant lung disease may suffer from severe pulmonary congestion due to excessive fluids, leading to impaired oxygenation.

Fluid administration is usually guided in healthy patients using hemodynamic parameters and urine output. Invasive monitoring such as central venous pressure or pulmonary capillary wedge pressure might be of help in patients with advanced cardiopulmonary dysfunction where tight management is required to maintain adequate cardiac output while avoiding excessive fluids.

Blood or blood products transfusion should be discussed preoperatively when there is a possibility of excessive blood loss requiring blood transfusion. For those who will not accept blood transfusion (e.g., Jehovah’s witnesses), the discussion should include their acceptance of other products such as cell salvage and albumin.

During anesthesia, hypothermia occurs due to imbalance between heat loss and heat production, as well as redistribution of heat from the central to the peripheral compartment. The rapid initial decline in temperature in the first hour of anesthesia occurs mainly due to redistribution of heat caused by peripheral vasodilatation. This leads to a shift in the warm blood from the core (viscera, central compartment) to the shell (skin, peripheral compartment). This initial phase of rapid heat loss is followed by a slower phase of gradual decline in temperature due to more heat loss than production. Eventually, the temperature reaches a plateau once the rate of heat loss is equal to heat production.