If you took one-tenth the energy you put into complaining and applied it to solving the problem, you’d be surprised by how well things can work out.
Introduction
Functional capacity is a major determinant of surgical outcome, since it is related to postoperative complications, activity and daily function, level of independence and quality of life (QoL) (see Chapter 2). Efforts to improve the recovery process have primarily focused on the postoperative period of convalescence, for example cardiac rehabilitation after bypass surgery or rehabilitation for orthopedic intervention (e.g. fracture of femur). The main purpose of this approach is to speed the healing of damaged tissues, replenish depleted physiological reserves and re-establish functional capacities in order to return to baseline values. However, the postoperative period may not be the best time to ask patients to make significant changes in their care. Patients after surgery complain of tiredness, fatigue, exhaustion and are concerned about perturbing the healing process as well as being depressed and anxious because of additional treatments. In addition, the presence of comorbidities might prolong the healing process.
The preoperative period may be a better time to intervene on those factors that contribute to recovery beyond the physical, and alleviate some of the emotional distress surrounding the anticipation of surgery and the recovery process (Carli and Minella 2017). In fact, during this time patients are more available for interventions aimed at optimizing the physiological reserve. These interventions should take into consideration the patient’s preoperative health status, the type of surgery and perioperative care.
The process of enhancing the reserve capacity of the individual before surgery to enable him/her to withstand the stress of surgery is defined as “preoperative conditioning or prehabilitation” (Figure 12.1). Functional capacity optimization includes, but is not limited to, endurance and resistance exercise, respiratory muscle training, hemoglobin optimization, smoking cessation, and nutritional and psychological counseling.
Figure 12.1 Trajectory of functional ability throughout the surgical process with no preoperative intervention (red) and with prehabilitation (green).
Although an increasing body of evidence shows the effectiveness of prehabilitation in enhancing preoperative physiological reserve, future studies are needed to identify the most appropriate protocols and assess the impact on other surgical outcomes.
Enhancing Functional Reserves: General Concepts
Exercise
Exercise is the single most effective intervention for increasing functional capacity, particularly in older adults (Chodzko-Zajko et al. 2009). Physical activity results in numerous beneficial effects for almost all health conditions, diseases and ages (WHO 2010), and it is getting more and more recognized as a medical intervention (Sallis 2009). This has led to the hypothesis that preoperative exercise training should play a key role in enhancing functional capacity and, therefore, improving surgical outcome (Chen et al. 2017). Although prehabilitation is not a new concept, recent studies suggest that a structured exercise program could optimize the preoperative physical fitness and improve functional outcome after surgery (Carli and Scheede-Bergdahl 2015). Whereas the impact on postoperative complications is still uncertain, good functional outcome has been shown in colorectal surgery (Gillis et al. 2014), even after neo-adjuvant chemo-radiotherapy (West et al. 2015), aortic (Barakat et al. 2016) and liver surgery (Dunne et al. 2016).
During endurance exercise, the rise in metabolic demand of the exercising muscles induces a physiologic increase in cardiac output – by modulating either stroke volume or heart rate – in ventilation and in muscle blood flow. Thus, exercise induces a physical stress that causes an adaptive response in all organs and tissues, and increases the ability to withstand a future stress (physical stress theory) (Mueller and Maluf 2002). The purpose of prehabilitation is to “precondition” the cardiorespiratory and musculoskeletal systems, thus improving functional outcome in preparation for surgical stress. However, it depends upon the exercise protocol adopted. Any bodily movements produced by a muscle contraction resulting in energy expenditure could be considered physical activity; exercise must be “planned, structured, repetitive, and purposive in the sense that the improvement or maintenance of one or more components of physical fitness is the objective” (USDHHS 2008).
The key elements of a preoperative exercise prescription within a multimodal prehabilitation program are presented in Table 12.1.
| 1. | Health status assessment:
|
| 2. | Exercise training program:
|
| 3. | Nutritional intervention:
|
| 4. | Psychosocial intervention:
|
HADS = Hospital Anxiety and Depression Scale (Zigmond and Snaith, 1983)
When designing a training program, it is recommended to follow the American Heart Association (AHA) and American College of Sports Medicine (ACSM) position paper (Nelson et al. 2007). Comprehensive history, physical assessment and subsequent personalized training design are essential to perform physical activity safely, especially in older adults. Table 12.2 shows contraindications to exercise.
ABSOLUTE
|
RELATIVE
|
Physical therapy in patients with severely impaired cognition and motion requires specific evaluation, and goes beyond the purpose of this chapter. There are three main categories of physical activity: aerobic, resistance and flexibility training. Table 12.3 provides practical examples of these different components in the context of a prehabilitation program. All the components of a physical therapy intervention complement each other, and lead to a comprehensive functional outcome improvement.
Table 12.3 Example of different components of exercise training in the context of a prehabilitation program
| Frequency | Exercise | Duration | Intensity | |
|---|---|---|---|---|
| Warm-up | Before every training session |
| 10 min |
|
| Cool-down | After every training session |
| 5 min |
|
| Flexibility | After every training session | 15–30 s per repetition
| 5–10 min | |
| Cardiovascular training | Three times a week | Moderate continuous training
| 20–30 min |
|
| Resistance training | Two to three times a week | 15 reps per set; 1 min rest between sets; 3 sets per exercise
| 45 min |
|
HRR – heart rate reserve; RPE – rating of perceived exertion (Borg scale 6–20); 1-RM – one repetition maximum. VO2max – maximum oxygen uptake
Aerobic Exercise
Age-related anatomical and physiological changes, sedentary behaviors, deconditioning and specific diseases cause impairment of aerobic capacity in the elderly. Endurance training is the cornerstone intervention for increasing aerobic capacity (Chodzko-Zajko et al. 2009). Aerobic training involves large muscle groups using oxygen-supplied energy. It aims to increase cardiovascular and respiratory endurance, defined as the ability to take up, transport and utilize oxygen. The exercise duration depends upon its intensity, but each bout should last 10 minutes at least. Older adults should do at least 150 minutes of moderate-intensity physical activity a week or 75 minutes of vigorous-intensity activity. Stationary and recumbent-type bikes, stair-climbing machines and treadmills are the most commonly used equipment.
Resistance Exercise
Resistance training is the main intervention for contrasting impaired muscle function and structure, which are common features in older adults (see below). Resistance exercise implies that muscles work or hold against an applied force or weight. Muscle-strengthening activities involving major muscle groups should be performed on at least two days a week (USDHHS 2008). Excentric resistance exercise at high intensity is most beneficial (Mueller et al. 2009). These exercises have the key role of providing the muscle with an overload stress, increasing power and strength.
Flexibility, and Static and Dynamic Balance
Reduced joint mobility can occur in the absence of disease in older adults, and any impairment could lead to activity limitation. Joint mobility examination is a mandatory component of comprehensive functional examination. Structural disease, joint pain and severely impaired gait or balance require specific evaluations and interventions, and are not a routine component of prehabilitation. Patients with poor mobility should perform physical activity three or more days per week in order to enhance balance and prevent falls (USDHHS 2008); stretching and strengthening exercises, and warm-up and cool-down activities should be part of the training session.
Exercise Intensity
Another important element of physical therapy prescription is the exercise intensity, as it is directly linked to both the amount of improvement in exercise capacity and the risk of adverse events (Hootman et al. 2001). The exercise intensity of endurance-type activity can be defined using:
Metabolic equivalents (METs): since physical activity raises metabolic expenditure, intensity may be estimated in terms of oxygen consumption. One MET is the resting oxygen uptake in a sitting position and equals 3.5 mL/kg/min. A 4 METs-activity would be an activity that utilizes roughly four times the amount of resting energy expenditure.
Maximal heart rate (HRmax) or heart rate reserve (HRR). HRmax is calculated with the traditional age-predicted equation: HRmax = 220 – age (years). HRR is defined as the difference between HRmax and HR at rest. Despite a strong linear relationship between heart rate and moderate-vigorous activity, HR is an unreliable measure of exercise intensity in older adults taking multiple medications (Kozey-Keadle et al. 2011).
Borg scale (rating of perceived exertion – RPE) (Borg 1970): a well-validated index that rates the perceived exertion, in which a score of 6 represents a resting activity with no effort and 20 represents an exhaustive exercise.
Maximum oxygen uptake (VO2max) and ventilatory threshold: cardiopulmonary exercise test (CPET) measure gas exchange and ventilation during an incremental exercise. CPET is the gold standard for aerobic exercise intensity assessment and prescription (Mezzani et al. 2012).
Regarding resistance training, exercise intensity can be prescribed using RPE or the One Repetition Maximum (1-RM: the maximum amount of weight a patient can lift just once).
Respiratory Muscle Training
Changes in lung and chest wall mechanics as a result of surgery and anesthesia could lead to diaphragm dysfunction, respiratory muscle and cough strength deficiency, reduced lung volumes, impaired muco-ciliary clearance and atelectasis (Hedenstierna 2010).
Preoperative respiratory physical therapy is a complex of preventative, non-pharmacological interventions aimed at improving respiratory muscle function in order to overcome breathing alterations and reduce complications after surgery. Incentive spirometry, deep-breathing exercises and other lung expansion maneuvres are the most common treatments. Preoperative respiratory exercise and education are strongly recommended by the ERAS (see Chapter 34) guidelines (Gustafsson et al. 2013). While preoperative ventilatory muscles training seems to ameliorate pulmonary function in patients undergoing major surgery, its role in preventing postoperative complications and prolonged length of stay (LOS) is controversial (Mans et al. 2015).
Optimizing Hemoglobin
Preoperative anemia is reported in up to three-quarters of surgical patients (Shander et al. 2004). Furthermore, even without anemia, iron and other hematinic deficiencies common among the elderly population could interfere with the capability to recover hemoglobin following surgery (Ralley 2014). Regardless of causes, preoperative anemia is related to mortality, morbidity, hospital LOS and allogeneic red blood cell transfusion (Fowler et al. 2015). Blood transfusion is by itself associated with increased morbidity and mortality due to infectious, immunological, pulmonary, thromboembolic and septic complications (Spahn and Goodnough 2013).
Optimizing erythropoiesis, minimizing blood loss and managing anemia are the key preoperative interventions. Figure 12.2 shows a proposal for preoperative anemia management (Goodnough et al. 2011). Implementation of multidisciplinary and individualized treatment of preoperative anemia has a central role in improving surgical outcomes and patient safety (Clevenger et al. 2015).
Figure 12.2 Algorithm for the detection, evaluation, and management of preoperative anemia. SF, serum ferritin; TSAT, transferrin saturation.
Smoking Cessation
Abstinence from smoking not only provides long-term benefits, but smoking cessation prior to surgery reduces the risk of postoperative complications, improves performance status and results in improved QoL (Sorensen 2012). In contrast, continuing to smoke increases the risk of postoperative complications, impairs wound healing, delays starting adjuvant chemotherapy, and increases recurrence and mortality risk (Sorensen 2012).
Behavioral, motivational or pharmacological interventions, such as varenicline or combination nicotine replacement therapy, should always be considered in a preoperative setting (Lindson-Hawley et al. 2015, Cahill et al. 2013).
Nutrition
Poor nutritional status (see Chapter 13) impairs functional capacity and is associated with postoperative complications (Garth et al. 2010). Elderly patients scheduled for surgery frequently deal with inadequate intake, and metabolic and inflammatory alterations that deregulate nutrient requirements or absorption (Nicolini et al. 2013). Disease and age-related changes in gastrointestinal function, cancer-associated structural and metabolic abnormalities and oncologic therapies could exacerbate malnutrition (Gillis et al. 2015).
The aim of preoperative nutritional intervention is not only the treatment of malnutrition, but the optimization of nutrient intake and metabolic function in order to withstand surgical metabolic stress, even in the absence of preoperative malnutrition. Furthermore, hallmarks of aging include progressive loss of muscle structure, mass and function, a process defined sarcopenia (Cruz-Jentoft et al. 2010). This is independently associated with a decline in mobility and functional capacity. Diet and physical activity are the main modifiable factors to counteract these deleterious changes. Resistance exercise is the cornerstone intervention (ACS 2009), but in order to generate a beneficial synergic effect between exercise and nutrition, exogenous amino acids should be administered to produce a state in which protein synthesis exceeds protein breakdown (Cermak et al. 2012).
In the context of a multimodal prehabilitation program, a specific assessment is performed by a nutritionist in order to estimate macronutrient intake, taking into account food habits (Table 12.1). Basic nutritional changes and protein supplementation in order to achieve a total protein intake of 1.5 g/kg/day are prescribed (McClave et al. 2013).
Enhancing Functional Reserve: The Patient with Cardiovascular and Respiratory Comorbidity
Chronic Obstructive Pulmonary Disease
Poor exercise capacity is an important systemic manifestation of advanced chronic obstructive pulmonary disease (COPD), and is associated with poor health-related QoL, exacerbations and increased postoperative risk (Celli et al. 2004, Smetana et al. 2006). Exertion dyspnea and skeletal muscle dysfunction limit the ability of patients with COPD to exercise, and the progressive deconditioning associated with inactivity initiates a vicious cycle. Exercise in this population can reduce symptoms, improve activity and daily function, and restore an acceptable level of independence (Spruit et al. 2013). Exercise reconditioning – the purpose of standard respiratory rehabilitation – is the result of a comprehensive intervention based on endurance and resistance exercise, breathing and respiratory muscle training, smoking cessation, pharmacological optimization, nutritional counseling, psychological support and patient education (Spruit et al. 2013). Based on this extensive consensus reached in pulmonary rehabilitation, a multimodal prehabilitation program (Table 12.1) could be considered, even in a perioperative setting.
Pharmacological optimization is another key concept. Medical treatment with inhaled bronchodilators and glucocorticoids should be tailored to achieve the best baseline level, considering the risk of increasing the dose of these medications in a surgical elderly patient. Lower airway infection and exacerbation of COPD are the main indications for delaying elective surgery. Purulent sputum or a qualitative change in the sputum indicate prompt antibiotic therapy and delaying elective surgery until symptoms return to baseline.
Cardiovascular Disease
Age-related cardiovascular changes are inevitable and cardiovascular diseases are common in older adults. In heart failure and ischemic heart disease, exertion-induced symptoms, limited maximal stroke volume and impaired heart rate response could limit exercise capacity (Kokkinos et al. 2000). Poor functional status is associated with an increased risk of perioperative and long-term cardiac events, and patients with functional reserve <4 METs scheduled for high-risk surgery should be considered for further diagnostic testing (Fleisher et al. 2014). For that reason, exercise tolerance assessment and improvement are key elements in preoperative management.
The American Heart Association strongly recommends rehabilitation programs for patients with recent myocardial infarction or unstable angina, chronic stable angina, heart failure, or recent myocardial revascularization, in order to both reduce risk factors and improve exercise capacity and survival (Smith et al. 2011). Either aerobic or strength training increase functional capacity. Safety of exercise training for cardiac patients is documented in several studies: in a study analyzing 25,420 cardiac surgical patients submitted to cardiac rehabilitation, only 15 severe cardiac events were reported, and the event rate was 1 per 49,565 patient-hours of exercise training (Pavy et al. 2006).
Although exercise is the main intervention, a multidisciplinary approach is also essential in a cardiac rehabilitation setting: adherence to medications, smoking cessation, patient education and counseling to improve nutrition habits and psychological wellbeing are recommended (Smith et al. 2011). Surgical multimodal prehabilitation based on the above interventions should therefore be considered safe and appropriate in these patients.
Medication Management (see also Chapters 4 and 37)
The potential role of preoperative initiation of β-blockers in reducing myocardial oxygen supply and demand (London et al. 2004) has led to several clinical trials with conflicting results (Devereaux et al. 2008, Dunkelgrun et al. 2009). Moreover, adverse effects such as bradycardia, hypotension and stroke are of particular concern in older adults. Long-term treatment for conditions such as ischemic heart disease should not be interrupted before surgery (Fleisher et al. 2014, Kristensen et al. 2014). Starting treatment with β-blockers should be only considered in patients with at least three cardio-vascular risk factors (e.g., heart failure, coronary heart disease, cerebrovascular accident, diabetes, renal insufficiency) undergoing high-risk surgery, between 30 days and 1 week before surgery, and only targeting hemodynamic response (resting heart rate of 60–70 beats/min and systolic blood pressure of >100 mmHg; Angeli et al. 2010). With the same purpose of decreasing sympathetic response to surgery, several α2-adrenoceptor agonists (clonidine, mivazerol, dexmetedomidine) have been tested. Clinical trials have yielded conflicting results, and their routine use is not indicated (Wijeysundera et al. 2003, Ji et al. 2013).
Statins, through their anti-inflammatory and plaque-stabilizing properties, play a strong role in cardiac protection. Discontinuation of a chronic therapy is not recommended, and perioperative initiation should be considered in patients undergoing vascular surgery (Kristensen et al. 2014). The use of angiotensin-converting enzyme inhibitors (ACE-inhibitors) is associated with higher incidence of transient intraoperative hypotension, but no other adverse effects have been shown (Turan et al. 2012). Discontinuation of a chronic therapy is therefore not recommended.
Aspirin, by the irreversible inhibition of platelet cyclo-oxygenase, has a main role in secondary prevention of cardiovascular disease, but increases the risk of bleeding. Although generally accepted, its perioperative administration is not associated with changes in mortality or non-fatal myocardial infarction rates, and increases the risk of major bleeding (Devereaux et al. 2014). Therefore, the risk of excessive bleeding should be weighted against the risk of thrombotic events in order to decide whether to continue or hold before surgery (Fleisher et al. 2014).
References
Findit@CUHK Library | Google Scholar | PubMed
Findit@CUHK Library | Google Scholar | PubMed
Findit@CUHK Library | Google Scholar
Findit@CUHK Library | Google Scholar | PubMed
Findit@CUHK Library | Google Scholar
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