2.1 Cardiac morbidity

Perioperative cardiac morbidity (PCM) is the leading cause of death during and after surgery and includes myocardial infarction (MI), congestive heart failure (CHF), unstable angina, serious dysrhythmia, and cardiac death [4, 5]. Stressors such as perioperative pain, blood loss, anesthesia, and fluid shifts all contribute to an imbalance between myocardial oxygen demand and supply [1]. In addition, the aging process results in specific changes to the autonomic nervous system including increased sympathetic nervous system activation, decreased parasympathetic activity, and decreased baroreceptor activity, limiting the ability of the older adult to respond effectively to surgical stress [1]. Older patients are more likely to have preexisting cardiac comorbidities, such as coronary artery disease (CAD) or congestive heart failure (CHF). These factors all contribute to a decrease in cardiovascular reserve and lower the threshold at which older adults develop cardiac complications and hemodynamic instability [4, 6].

2.2 Pulmonary morbidity

Normal aging results in clinically significant changes in the respiratory system, including loss of alveolar surface area, decline in intercostal muscle mass and strength, kyphotic thoracic spine changes, and calcification of rib cage cartilage [7]. These changes reduce chest wall compliance, elastic recoil of the lungs, and the strength of the respiratory muscles [8, 9]. Normal central respiratory responses to hypoxia and hypercapnia are reduced by approximately 50% in older adults [10]. The cough reflex is less forceful and effective, increasing the risk of aspiration pneumonia [9]. Older patients have increased sensitivity to the respiratory depressant effects of opioids due to an increase in the volume of distribution as well as a decrease in renal and hepatic clearance [9, 11].

2.3 Cognitive dysfunction

Older adults are especially susceptible to delirium in the perioperative period, and there is concern that perioperative delirium may also contribute to longer-term cognitive dysfunction [12] (see chapter 1.14 Delirium for more information on delirium). An abrupt decline in perioperative cognition is a robust predictor of increased mortality within the first 3–12 months after surgery [12–14]. Theories explaining the relationship between cognitive dysfunction and mortality include direct damage to the brain, inability of patients with cognitive impairment to care for their own health, and consideration of cognitive decline as an indirect marker of systemic organ disease [14].

Medical complications such as pneumonia, deep vein thrombosis, pressure ulcers, MI, gastric ulcers, and depression are more common in patients with postoperative delirium [15].

Since cognitive decline in the postoperative period can have an enormous impact on postoperative complications and functional recovery, minimization of delirium in the perioperative period is an important goal.

3.1 Functional capacity

Functional capacity is a more accurate predictor of intraoperative risk than most specific comorbid conditions or the results of extensive diagnostic testing [17].

Functional capacity can be assessed in terms of metabolic equivalents (METs) of activity. Ability to perform activities of greater than four METs is considered good functional capacity; examples of such activities include climbing up a flight of stairs, walking more than 6.4 km/h (4 mph), or doing heavy household work [18]. This threshold (> 4 METs) has been used to indicate adequate reserve for most orthopedic and other intermediate-risk surgeries.

3.2 Cardiac risk

While the development of robust risk assessment tools is of increasing relevance for elective surgical procedures, there remains a dearth of studies to accurately estimate risk for the typical FFP. The Revised Cardiac Risk Index [19] is the most widely studied tool for hip fracture surgery and stratifies cardiovascular risk based on the presence of six predictors of cardiac morbidity and mortality:

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  High-risk surgery (typically vascular or intraperitoneal)

  
  
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  History of ischemic heart disease

  
  
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  History of CHF

  
  
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  History of cerebrovascular disease

  
  
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  Insulin-dependent diabetes

  
  
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  Preoperative serum creatinine > 2 mg/dL

The presence of two or more factors identifies patients with moderate to high risk for perioperative complications. These criteria have been used during elective surgical planning as triggers to consider additional noninvasive testing, further medical therapy, and/or invasive monitoring [17, 19]. These factors are likely to also predict outcomes in the urgent surgical setting.

History of unstable angina, CHF, significant dysrhythmias, severe valvular disease, and pacemaker or an automated implantable cardioverter defibrillator (ICD) placement should be determined [18]. If a patient has a pacemaker or an ICD, a plan for perioperative management should be discussed. Information to be obtained includes the type and manufacturer of the device as well as the underlying dysrhythmia or other cardiac condition that led to the placement of the device. Perioperative management of the device must be individualized, with some devices requiring preoperative interrogation and possibly reprogramming by the cardiology team [18].

3.3 Procedure risk

In addition to risk stratification for patients, surgical procedures may also be classified according to risk. High-risk procedures include emergent procedures, major vascular procedures, and prolonged procedures with major fluid shifts and blood loss. They are typically defined as having adverse cardiac event risks greater than 5%. Low-risk procedures include endoscopy, breast surgery, and cataract surgery and have an adverse cardiac event risk lower than 1%. Most orthopedic procedures are considered intermediate risk and have an adverse cardiac event risk between 1% and 5% [18].

3.4 Routine preoperative testing

Only after clinically significant diseases have been identified on a medical history and physical examination should further testing be considered; this testing should only be pursued if it is likely to change management, improve outcomes, and provide benefits that outweigh the harms of surgical delay [18] (see also chapters 1.4 Perioperative risk assessment and preparation and 2.6 Orthogeriatric team—principles, roles, and responsibilities). In hip fracture patients, operative delay of more than 48 hours after admission increases the odds of a 30-day mortality by 41% and a 1-year mortality by 32% [20].

The American Society of Anesthesiologists in collaboration with the American Board of Internal Medicine Foundation recommend the following baseline preoperative laboratory tests: complete blood count, basic or comprehensive metabolic panel (ie, electrolytes, renal function and glucose), and coagulation studies for patients when significant blood loss and fluid shifts are expected [21].

In patients with established heart disease, an electrocardiogram may provide important prognostic information about short-term and long-term mortality, and provides a baseline against which perioperative changes may be judged [18].

More advanced preoperative cardiac testing (eg, transthoracic/esophageal echocardiography or cardiac stress testing) in asymptomatic, stable patients with known cardiac disease (eg, CHF or valvular disease) is not recommended and is generally not appropriate for hip fracture patients in the absence of signs and symptoms of significant active cardiovascular compromise [21, 22].

With the exception of concern for severe aortic stenosis, echocardiographic assessment of valvular function does not lead to clinically important changes in management [18].

3.5 Medication management

All preoperative medications must be correctly identified, recorded and considered for continuation or discontinuation during the perioperative period. The risk of intraoperative hypotension and excessive blood loss is elevated in older trauma patients, and teams must consider the potential impact of home medications on blood pressure and bleeding. Some common perioperative considerations include:

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  Long-term beta-blocker therapy should be continued perioperatively due to the benefits of heart rate control and decreased myocardial oxygen consumption, and the potential harm of withdrawal when abruptly stopped [18]. In patients not receiving long-term beta-blocker therapy, beta-blockers should not be initiated prior to surgery due to the increased risk of hypotension, stroke, and death [18].

  
  
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  Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) can lead to increased episodes of intraoperative hypotension and acute kidney injury, particularly when used in association with diuretics [23]. Most experts recommend discontinuation of ACE inhibitors/ARBs and diuretics preoperatively [17].

  
  
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  Long-term antiplatelet therapy with aspirin, clopidogrel and other antiplatelet agents is typically stopped in the preoperative period. For patients who have undergone coronary stent implantation within the past 6 weeks, dual antiplatelet therapy with aspirin and P2Y12 platelet inhibitor should be continued unless the risk of surgical bleeding outweighs the risk of stent thrombosis [18].

Additional discussion of preoperative medication management can be found in chapter 1.4 Preoperative risk assessment and preparation. Discussion of the management of long-term anticoagulation during the perioperative period can be found in chapter 1.6 Anticoagulation in the perioperative setting.

4.1 Definitions and concepts

General anesthesia is typically delivered through a combination of intravenous and inhalational agents and results in loss of consciousness, lack of response to stimuli and typically requires ventilatory support.

Regional anesthesia encompasses neuraxial (NA) techniques (eg, epidural and spinal anesthesia), and peripheral nerve blockade. Regional anesthetic techniques can be combined with systemic sedatives, but do not typically involve complete loss of consciousness or the need for complete ventilator support.

The stress of surgery causes a cascade of neural and humoral mediators that trigger tachycardia, blood pressure lability, and hypercoagulability, and can lead to MI, pulmonary infection, and thromboembolism [23]. Since pain plays a central role in triggering this stress response, effective analgesia can mitigate the ensuing adverse effects on various organ systems and improve outcomes [25]. General anesthesia modulates this response through the central nervous system, while RA blocks this pathway at the level of peripheral nerves or at the spinal cord [26].

Effective management of pain in the postinjury period is crucial, as uncontrolled pain may lead to both short-term complications and chronic pain syndromes [26].

Unlike RA, adequate blockade of the surgical stress response under GA requires large doses of opioids given prior to incision [25, 27]. Large doses of opioids increase the incidence of opioid-related adverse effects such as respiratory depression, sedation, nausea, ileus, and pruritus.

The addition of epidural anesthesia blocks the perioperative increases in adrenaline, cyclic adenosine monophosphate [28], renin, aldosterone, cortisol [29, 30], and vasopressin [31]. When epidural anesthesia is begun prior to surgery and maintained for 24 hours after surgery, muscle catabolism is minimized [32].

As noted previously, some aspects of this stress may be reduced by the administration of RA [1].

4.2 General versus neuraxial anesthesia

General anesthesia is required for patients with contraindications to NAs (eg, coagulopathy, infection at site, increased intracranial pressure), and may be preferred by some anesthesiologists and surgeons for patient-specific or procedure-specific issues. Some literature [33] suggests that regional techniques are associated with less delirium and fewer perioperative complications, but anesthetic practice varies greatly worldwide, and there are no large randomized trials of FFP to definitively inform this question [1, 24, 34]. For fractures of or trauma to the lower extremity, spinal, epidural, nerve blocks and GA may be used to provide anesthesia and analgesia. Proximal humeral fractures typically require GA in the FFP population.