Metabolic equivalent
Activity
1
Watching television
2
Walking very slow (<2 mph)
3
Office work
4
Golfing with a cart
5
Normal walking
6
Shoveling snow
7
Fast jogging
8
Jumping jacks
9
Running 4–5 mph
10
Running 6 mph
The general approach in assessing patients for adverse cardiac events involves risk stratification [5]. The goal is to estimate the perioperative risk of a major adverse cardiac event (MACE ) on the basis of a combined risk of the surgical procedure along with clinical risk factors. This estimate can be obtained from the American College of Surgeons NSQIP surgical risk calculator [13] or with the use of the RCRI with an estimation of risk from the surgical procedure. The proposed ACC/AHA algorithm starts with step 1 in Fig. 4.1. Patients undergoing emergency procedures or who are at low risk of MACE (<1%) should proceed without additional work-up, because routine screening with noninvasive stress testing is not useful for low-risk patients. For patients with elevated risk, further evaluation such as functional status should be assessed. If the patient can tolerate ≥4 METS activity, then it may be reasonable to proceed without further testing. Exercise testing or noninvasive pharmacological stress testing to assess for myocardial ischemia should be considered for high-risk patients with unknown or <4 METS function capacity if the results will change management. For patients who have undergone further testing, they may proceed with surgery if the stress test is negative for ischemia.
Fig. 4.1
Suggested approach for cardiac work-up of patient presenting for noncardiac surgery . Step 1: Proceed with surgery if procedure is emergency or patient is at low risk for MACE. Steps 2 and 3: Patients at high risk for MACE with good functional status (≥4 METS) can reasonably proceed. Step 4: Cardiac stress testing should be considered in patients with unknown or low functional status (<4 METS) if management will change depending on the results. Step 5: If stress testing is negative for ischemia, patients may reasonably proceed with surgery. If stress testing is positive for ischemia, risks and benefits of coronary revascularization will need to be assessed against the risk of the surgery (Based on data from Ref. Fleisher et al. [5])
Whether myocardial revascularization should be performed before noncardiac surgery depends on whether the combined risk of coronary angiography plus myocardial revascularization exceeds the risk of the proposed noncardiac surgery without revascularization [14, 15]. Coronary revascularization is not recommended before noncardiac surgery exclusively to reduce perioperative cardiac events [5].
Preoperative Management
Beta-Blockers
Beta-blockers are anti-ischemic because inhibition of beta receptor stimulation by catecholamines results in slowing of heart rate and contractility, and the resulting action is a decrease in myocardial oxygen consumption. However, a multinational trial of metoprolol versus placebo in 8,351 patients found that although fewer patients in the metoprolol group had a myocardial infarction, more patients in the metoprolol group died and had an increased incidence of stroke [16]. Results from this study substantially dampen the enthusiasm in implementing new preoperative beta blockade in at-risk patients. Beta-blockers should be continued in patients who are on them chronically, but beta-blocker therapy should not be started on the day of surgery [5]. Currently, there is insufficient data on the efficacy and safety of starting beta-blockers days to weeks in advance of the noncardiac surgery to make a firm recommendation [17].
Statins
Lipid-lowering drugs have been shown to help prevent adverse cardiac events [18], but the data are limited in terms of the number of enrolled patients and the type of surgical procedure. Durazzo et al. studied the effect of short-term treatment with atorvastatin in patients undergoing vascular surgery. The placebo group had a threefold higher incidence of adverse cardiac events than the intervention group (26% vs. 8%, p = 0.031) [19]. Although, the time of initiation of therapy and the duration of therapy are not clear, current recommendations are that statins should be continued in patients currently taking them, and perioperative initiation is reasonable in patients undergoing high-risk procedures [5].
Hypertension
Hypertension is a risk factor for ischemic heart disease, congestive heart failure, and stroke. The risk of nonfatal myocardial infarction in patients with diastolic hypertension (>90 mm Hg) is increased markedly in the presence of hypercholesterolemia, cigarette smoking, and ECG abnormalities [20]. Although the presence of preoperative hypertension has not been conclusively shown to increase the incidence of postoperative cardiac complications, preoperative withdrawal of antihypertensive medications, such as beta-blockers, calcium channel blockers, or clonidine, is associated with greater perioperative blood pressure lability.
Congestive Heart Failure
Depressed preoperative ejection fraction (<35%), determined by radionuclide angiography, has been found to correlate significantly with early perioperative infarction [21]. Of importance is that clinical diagnosis of heart failure in older patients is particularly difficult because of the lack of typical symptoms and physical findings [22]. In patients with a history of congestive heart failure, one-third may present with normal systolic function [23], making assessment of diastolic filling in these patients particularly important. The prognostic importance of preoperative diastolic dysfunction on perioperative cardiac morbidity remains to be determined. However, the presence of clinical signs of congestive heart failure is a major risk predictor of postoperative cardiac complications, and surgery should be delayed if possible until the heart failure is stabilized [24].
Other Risk Factors
The relative importance of other preoperative risk factors such as hypercholesterolemia, cigarette smoking, valvular heart disease, and site of surgery has not been conclusively determined to increase perioperative cardiac risk.
Pulmonary Evaluation
With aging, there is loss of elastin and increased lung compliance with decreased lung elastic recoil, air trapping, and hyperinflation. Residual volume increases 5–10% per decade, and functional residual capacity (FRC) increases 1–3% per decade [25]. The loss of elastic recoil also increases closing volume and leads to early collapse of small airways, which leads to more ventilation-perfusion mismatch and a larger A-a gradient [26]. There is also an age-related increase of pulmonary vascular resistance that averages to 1 mm Hg increase of pulmonary artery systolic pressure per decade [27].
With increasing age, there is narrowing of the thoracic intervertebral disk space and the intercostal space, which can change the vertebral angle and decrease the forced exhaled volume in 1 s (FEV1) and vital capacity by up to 30 cc/year. Chronic smokers have a more accelerated decline in lung function [28]. Older patients also develop sarcopenia which leads to decreased skeletal muscle mass and strength. Weaker diaphragmatic inspiratory effort may decrease the patient’s ability to increase minute ventilation on demand. There is also dysfunction of the mucociliary clearance ability.
Preoperative Assessment
Five preoperative predictors of increased risk for postoperative respiratory failure have been identified which include type of surgery, emergency case, poor functional status , preoperative sepsis, and higher ASA class [29]. In contrast, no laboratory value or preoperative testing performed in unselected patients has been associated with predictive value for postoperative respiratory failure. Pulmonary function tests can assess the presence and severity of disease, but they do not have great ability to predict postoperative need for mechanical ventilation or complications. In a study involving critically ill patients, the CO2 levels on arterial blood gas and not spirometric testing better predicted the need for postoperative intubation [30]. The evidence to date suggests that pulmonary function tests should be selectively performed in patients undergoing nonthoracic surgery, because they can assess the presence and severity of the disease, but they do not have great predictive value for postoperative pulmonary complications.
Preoperative Management
Asthma
The incidence of asthma in older patients has been reported to be around 7%, which is comparable to other adult age groups [31]. Asthma can be underdiagnosed in the older individual because the symptoms may be misinterpreted as normal aging or other conditions such as heart failure, gastroesophageal reflux, pneumonia, or side effects of medications such as beta-blockers or angiotensin-converting enzyme inhibitors. The treatment of asthma is basically similar to the general adult population because there is lack of data targeting the older patient. Specifically, many of the trials excluded patients > age 60. Once the diagnosis is established, disease optimization should focus on smoking cessation, optimization of medications, exercise training, and patient education [32].
Chronic Obstructive Pulmonary Disease
The preoperative management should be focused on medically optimizing patients with pulmonary disease. Acute exacerbations of chronic obstructive pulmonary disease (COPD) should be aggressively treated, and surgery may need to be delayed until symptoms improve. COPD is more an independent predictor for postoperative pulmonary complications than asthma [33].
Smoking Cessation
Smoking cessation counseling is probably the most essential risk modifier for pulmonary complications. Moller et al. showed that smoking intervention successfully reduced the incidence of postoperative complications in patients undergoing elective hip or knee arthroplasty [34]. While maximal reductions in postoperative respiratory complications are seen with at least a 2-month abstinence, smoking cessation should be encouraged even immediately before surgery, because smoking cessation immediately preoperatively has been associated with decreased carbon monoxide levels, increased oxygen carrying capacity, and reduced operative risk measured at 6 weeks after surgery [35].
Obstructive Sleep Apnea
Moderate to severe obstructive sleep apnea (OSA ) occurs in about 10–20% of the general population [36]; importantly, the prevalence of OSA increases with aging due to weakening of pharyngeal muscle tone, which may lead to upper airway dysfunction. Obesity may increase with age and also contributes to OSA. More than one-third of older adults aged ≥65 years met definition for obesity in 2007–2010 [37]. In nonsurgical patients, patients who have severe sleep apnea and are not treated have a greater rate of death than heavy smokers over a 10-year period [38]. OSA is also associated with higher risk of postoperative desaturation, respiratory failure, postoperative cardiac events, and transfers to the intensive care units in adults [39]. The optimal time to administer continuous positive airway pressure (CPAP) treatment before surgery is not clear, but Mehta et al. showed that patients who were newly diagnosed with sleep apnea in the preoperative clinics and were referred to receive their CPAP therapy were able to have improved sleep quality, less daytime sleepiness, and greater reduction in medication for other comorbidities such as hypertension and diabetes [40].
Exercise
Exercise training interventions preoperatively have shown mixed results in terms of preventing pulmonary complications. Part of the inconsistency is due to the heterogeneity in study design in terms of type of exercise used, duration, frequency, and timing. Preoperative exercise programs can be effective in promoting quality of life among patients diagnosed and treated for locally advanced rectal cancer [41], but not all studies have shown efficacy due to issues with patient compliance. Hopefully in the near future, studies that objectively measure functional capacity and perioperative morbidity will be able to expand our understanding of the effects of exercise training preoperatively.
Inspiratory Muscle Training
After surgery, reductions in inspiratory and expiratory muscle strength can persist for up to 12 weeks. Preoperative inspiratory muscle training (IMT ) is intended to increase strength and endurance by adding a resistive load during inspiration. Although not specifically studied in the older patient, a recent Cochrane review found reduced postoperative atelectasis, pneumonia, and hospital length of stay with IMT preoperatively for adult patients undergoing cardiac or major abdominal surgery [42]. More studies are needed before IMT can be recommended for all older patients undergoing surgery.
Neurologic Evaluation
The human brain begins to atrophy by the third decade. Normal age-related changes include decrease ability to multitask, reduced speed of information processing, and decreased language comprehension for complex text. The pulsatility and velocity induced by aortic stiffness penetrates further into the brain’s microcirculation and can cause damage to the small vessels because of its low vascular resistance. This small vessel disease then can lead to lacunar infarcts and microbleeds and may lead to loss of cognitive function in some patients.
After noncardiac surgery, the two most common complications in the older individual are delirium (10–60%) [43] and postoperative cognitive decline (POCD ) (7–26%) [44]. Delirium is an acute confusional state with alterations in attention and consciousness [45] (see Chap. 30), while POCD refers to declines in cognitive functioning that can occur in the absence of delirium and are detected through neuropsychological testing. Delirium occurs in 14–50% of hospitalized medical patients, and it is associated with higher mortality rate [46, 47], increased medical complications, longer hospital stay, and poorer short-term functional outcome. Delirium can be superimposed on dementia or other neurologic disorders associated with global cognitive impairment. As a result, the course of delirium can vary considerably and depends on the resolution of the causative factors.
Preoperative Assessment
The development of delirium is thought to be a multifactorial process involving baseline patient vulnerability and precipitating factors or insults [48]. The diagnosis of chronic cognitive decline in the preoperative period has been found to be the strongest predictor of postoperative delirium [43]. Other preoperative risk factors for postoperative delirium include sensory impairment, age ≥70, polypharmacy, poor functional status , dehydration, medical comorbidities (especially cerebrovascular or other brain diseases), electrolyte abnormalities, low albumin, depression, and pain [12]. The estimated prevalence of cognitive impairment not categorized as dementia is over 20% in the older population [49]. Identifying individuals with cognitive impairment before surgery is important for risk stratification and helps providers anticipate perioperative cognitive problems and postoperative management needs [50].
Preoperative testing for preexisting cognitive impairment is not yet a part of routine clinical practice because many tests can be time-consuming, but several quick and simple cognitive screening tools suitable for the preoperative setting with sensitivity ranging from 79% to 99% and specificity ranging from 70% to 98% have been proposed (Table 4.2) [51]. One final quick test is the animal fluency test. This test requires patients to name as many animals as possible within 60 seconds. Patients with lower scores on the animal fluency test are at higher risk of developing postoperative delirium [52]. Recently, the American Geriatrics Society published a best practice statement about postoperative delirium and strongly recommended assessment and documentation of preoperative cognitive function in older adults at risk of postoperative delirium [53]. The hope is that utilization of cognitive screening tools can contribute to early recognition of cognitive decline and serve as a record of baseline cognitive status.
Table 4.2
Cognitive screening tests that can be administered in less than 3 min
Test name | Abbreviation | Components |
|---|---|---|
6-item screener | 6-IS | Three-item recall (i.e., apple, table, penny) Three-item temporal orientation (i.e., day of week, month, year) |
8-item screener | 8-IS | Three-item recall Attention/calculation exercise for five iterations (i.e., subtract 7 from 100 for 5 iterations) |
6-item cognitive impairment test | 6-CIT | Three-item temporal orientation Five-item address (i.e., first name, last name, house number, street, city) |
Sweet 16 | S-16 | Eight temporal/spatial orientation (i.e., time, place) Three-item immediate recall Two sustained attention questions (i.e., digit spans backwards) Three-item recall |
5-item recall and fluency | 5-IRF | Five-item address recall 1-min animal fluency (i.e., name as many different animals as possible in 1 min) |
Mini-cog | Three-item recall Clock drawing (i.e., draw numbered clock face with hands showing 11 o’clock) |
Preoperative Management
Comprehensive Assessment
Management of postoperative delirium centers on prevention and early recognition. Medical prophylaxis has been demonstrated to have limited utility since most of the therapeutic options are for symptom management and not for prevention and do not improve outcomes [54]. Other successful interventions of postoperative delirium are limited as well. The most successful study was by Marcantonio et al. [55]. In this study, older patients admitted for emergency surgical repair of hip fracture were randomly assigned to an intervention (a comprehensive geriatrics assessment) or the usual care. Delirium occurred in 32% of the intervention patients and in 50% of the usual care patients. Despite this reduction in delirium, the length of hospital stay did not differ significantly between the two groups.
Multimodal Pain Management
The use of multimodal pain management regimens involves several different anesthetic and analgesic techniques that have been shown to decrease postoperative opioid use. For a detailed discussion of intraoperative anesthetic management (regional versus general anesthesia), the reader is encouraged to refer to Chaps. 19 and 28 in this book, but the use of multimodal pain management regimens often start in the preoperative period. While not selecting specifically for older patients, studies that look at treatment for hip fractures often end up predominantly with older patients, because hip fractures are a leading cause of morbidity and mortality in this age group [56]. Multimodal regimens include non-opioid medications such as acetaminophen, regional blocks, and gabapentin or pregabalin. Kang and colleagues showed that among cognitively intact older patients undergoing bipolar hemiarthroplasty, multimodal analgesia including preoperative oral oxycodone and celecoxib and intraoperative periarticular injections led to lower visual analog scale (VAS) scores and less fentanyl use. The incidence of postoperative delirium and hospital stay did not differ between the two groups, but the study was small and did not have enough power [57]. With preoperative planning and use of multimodal pain management regimens, older patients may be mobilized earlier, use less narcotics, and have lower pain scores without unwanted narcotic side effects.
Exercise
There is reduced risk for mild cognitive impairment and dementia in older adults who participate in physical exercise . Multiple physiologic mechanisms such as elevated neurotrophin levels, improved vascularization, facilitation of synaptogenesis, mediation of inflammation, and reduced disordered protein deposition along with reduction of cardiovascular risk factors likely account for the neuroprotective effects of exercise on brain structures. Regular aerobic exercise may well provide a protective effect on brain health and cognitive performance through the prevention and management of hypertension and subsequent enhanced cerebral blood flow. Women in the Nurses’ Health Study, age 70–80, who walked 90 min per week, had global cognitive scores higher than those who walked less than 40 min per week [58]. For men in the Honolulu-Asia Aging Study, those who walked less than 1 mile per day were at significantly higher risk (1.7–1.8 times) for developing dementia compared to men who walked more than 2 miles per day [59]. Although the optimal exercise amount and type remain unknown, positive relationships between a higher dosage of exercise and cognitive health have been reported in aging adults [60]. There is some evidence that resistance-only training can also have a positive effect [61]. Moderate intensity physical exercise can lead to significant changes in brain health and cognitive performance, including memory, attention, and executive function. While the benefits of exercise are considered preventative, this is probably more of a long-term effect, and it is not realistic to expect benefit in the few days before surgery. Also, exercise training has not been tested extensively in presurgical populations for postoperative outcomes, nor have specific types of beneficial exercise been well delineated [62].
Hydration
Radtke et al. enrolled over 1000 surgical patients at a single center and found that patients who had preoperative fluid fasting of 2–6 h had a significantly reduced incidence of delirium in the recovery room (odds ratio 2.69, 95% confidence interval 1.4–5.2) and on the ward (odds ratio 10.57, 95% confidence interval 1.4–78.6) compared with those who fasted for more than 6 h. While preoperative dehydration does hold biological plausibility, it seems unlikely that the fluid management intraoperatively did not reduce this association. Further work including randomized controlled trials will be needed to determine if treatment of preoperative dehydration alone can lead to a reduction in the occurrence of postoperative delirium [63].
Depression/Anxiety
The incidence of depression increases in the older individual. In female patients age > 65 years, the number of patients who screened positive for depression across age groups was 5.9% (age 65–74 years), 6.3% (75–84 years), and 10% (85 years and older) [64]. Depression is associated with poorer prognosis, longer recovery times, increased health-care utilization, and postoperative delirium [65]. Preoperative anxiety along with depression symptoms have been associated with increased mortality [hazard ratio = 1.88 (95% CI = 1.12–3.17), P = 0.02] [66] and worse functional status [67]. Studies looking at psychological interventions have been difficult due to preexisting personality type and traits, confounding medical factors, and heterogeneity among trials. Further research is needed to determine what preoperative interventions would be effective in the short preoperative time period.
Multicomponent Packages
The literature about preoperative optimization of cognitive status is growing rapidly. The positive evidence so far points to reduction in the incidence of delirium with the use of multicomponent/multidisciplinary prevention packages. The individual components of the interventions varied between studies but commonly included reorientation strategies, ensuring hydration/nutrition, and early mobilization [68]. There remains a lot to study about target-specific interventions.
Frailty
Frailty, a syndrome that is thought to be separate from delirium, is also common among the older population . Frailty is currently conceptualized as a syndrome that results in a myriad of signs and symptoms and is characterized by susceptibility to impending decline in physical function and negative health outcomes including increased risk of mortality [69] (see Chap. 1). In other population studies, such as the Rush Memory and Aging Project, a longitudinal study of aging [70] found that increasing frailty was associated with Alzheimer’s disease and increased rate of cognitive decline. Other studies reported that signs of frailty , such as grip strength, gait disturbance, and body composition, have been related to mild cognitive impairment [71–74]. In surgical patients , preoperative frailty has been shown to increase the risk of postoperative complications [75–77] and postoperative delirium [78] in patients undergoing elective surgery.
Preoperative Assessment
Currently, there is no consensus as to how frailty should be measured. Although there are different views on the specific criteria, operational definitions of frailty have been proposed including excessive reduction in lean body mass, poor endurance associated with a perception of exhaustion and fatigue, and a reduction in walking speed and mobility [69]. Other features have been described such as loss of appetite, reduced nutritional intake, and deteriorations including but not confined to the cardiovascular, metabolic, and immunologic systems [79–81]. Although there is no consensus as to how frailty should be defined, two proposed definitions, including physical frailty [69] and cognitive frailty [82], have been shown to be associated with outcomes such as functional decline, cognitive decline, mortality, readmission, and nursing home placement [83].
In one study of older patients admitted to a Veterans Hospital, 27% were found to be frail. Our study showing that one-third of the patients had a frailty score of 3 or greater is similar to that reported by a previous study showing that 27% of older patients admitted to a Veterans Hospital were considered frail [84]. Another important consideration is whether frailty is dynamic and potentially reversible. Considering that half of the patients in one study were pre-frail [78], whether interventions would reduce the development of frailty is clinically relevant.
Preoperative Management
Prehabilitation
Prehabilitation, which is defined as the enhancement of the preoperative condition of a patient, is a possible strategy to improve the postoperative outcome of patients who are identified to be frail preoperatively. This emerging concept proposes the preoperative optimization of physical, nutritional, and mental status for those who are identified to be frail preoperatively. A more detailed review of this topic is discussed in Chap. 6.
Renal Function
The prevalence of renal insufficiency is quite common in the older individual because of a decrease in glomerular function with age . Chronic kidney disease (CKD) is not an inevitable consequence of aging, but age-associated changes probably enhance susceptibility to the development of CKD. In populations ≥ age 70, an abnormal glomerular filtration rate was observed in 75% of community-dwelling older individuals, 78% of the patients from the geriatric ward, and 91% of nursing home patients. In populations ≥ age 85, 99% had evidence of renal impairment necessitating dosing adjustments for drugs [85]. Kheterpal et al. identified aged ≥59 years along with emergent surgery, liver disease, body mass index (BMI) ≥32 kg/m2, high-risk surgery, peripheral vascular occlusive disease, and COPD necessitating chronic bronchodilator therapy as independent preoperative predictors of postoperative acute kidney injury (AKI) [86]. Emerging evidence suggests that even minor changes in serum creatinine are associated with increased patient mortality after major surgery [87]. In fact, it is estimated that acute renal failure contributes to at least one of every five perioperative deaths in older surgical patients [88].
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