Physical Intervention

Patients with adequate pre-operative physical activity and inspiratory muscle strength had better post-operative outcomes and shorter length of hospital stay.16 Eight studies (five randomized controlled, one systematic review, one meta-analysis, and two cohort studies) were identified for physical interventions before surgery and are summarized here. A systematic review that assessed the effect of pre-operative physical fitness on post-operative outcomes after abdominal surgery showed that prehabilitation consisting of inspiratory muscle training, aerobic exercise, and/or resistance training decreases post-operative complications after abdominal surgery (odds ratio 0.59, 95% confidence interval (CI) 0.38 to 0.91; p=0.03).17 Therefore, physical training (ie, exercise and inspiratory muscle training) is the main target of most prehabilitation programs.

Functional capacity is commonly evaluated by cardiopulmonary exercise testing; however, this requires significant resources including equipment, personnel, and expertise.18 Alternatively, exercise capacity is evaluated by the 6-min walk test (6-MWT), which is a reproducible test that has been validated in surgical populations. 6-MWT is associated with the capacity to perform daily activities, and registers the maximum distance a patient is able to walk during 6 min at moderate intensity.19 20 This test is linearly correlated to maximum oxygen consumption (VO₂max) that is associated with post-operative morbidity and complications.21 Patients who walked <350 meters experienced more short-term and long-term morbidity and higher mortality.22

There is large heterogeneity according to type, intensity, duration, timing, and supervision of exercise interventions in prehabilitation programs; however, most have been proved to improve recovery after surgery and reduce post-operative complications. Soares et al compared 16 patients undergoing upper abdominal surgery, assigned to receive two supervised and four unsupervised exercise sessions for 2–3 weeks pre-operatively, to 16 control patients without physical therapy. Patients in the intervention group had higher inspiratory capacity before surgery and 6-MWT on post-operative day 7 (p<0.05). Moreover, post-operative complication rates were reduced in the intervention group (31.3% vs 68.7%; p=0.03).23 Barberan-Garcia et al developed a personalized exercise prehabilitation program in high-risk patients undergoing major abdominal surgery. This involved one to three supervised sessions per week based on a cycle-ergometer stationary bicycle combined with a daily unsupervised personalized program. The prehabilitation group achieved better aerobic capacity during the pre-operative period (p<0.001) and the rate of post-operative complications decreased (31% vs 62%; p=0.001).15 In colorectal surgery, Carli et al compared 58 patients randomized to a daily unsupervised structured cycling and strengthening program, to a control group with an unsupervised daily walking and breathing program (54 patients). There were no differences between the groups in mean functional walking capacity over the prehabilitation period or at post-operative follow-up. In fact, post-operative improvement was greater in the control group (41% vs 11%; p=0.019). Nevertheless, a compliance rate of only 16% was reported.24 Gillis et al compared a prehabilitation group based on home-based unsupervised exercise for at least 3 days per week before surgery with a rehabilitation group that initiated exercise at home after surgery. Although the mean baseline walking capacity measured by 6-MWT was the same between groups, functional walking capacity increased in a higher proportion in the prehabilitation group compared with the rehabilitation group (53% vs 15%, p=0.006%, and 84% vs 62%, p=0.049, respectively) over the peri-operative time and 8 weeks after surgery. Complication rates and length of hospital stay were similar between groups.25

Physical intervention in prehabilitation programs may also include inspiratory muscle training. Dronkers et al reported an association between adequate pre-operative inspiratory muscle training and shorter length of hospital stay after major oncological abdominal surgery.16 In elective cardiac surgery, pre-operative inspiratory muscle training reduces post-operative pulmonary complications.26 Similar effects are suggested for thoracic, abdominal, and orthopedic surgery.27 Inspiratory muscle training involves 15 to 30 min daily sessions using an inspiratory threshold-loading device with a patient-tailored program or daily home breathing exercises through a flow volume incentive spirometer.28

Lastly, physical intervention can be home-based or can be performed under the supervision of a healthcare provider. Although both types of training have been reported to be beneficial, supervised structured exercises encourage patient compliance and enhance functional capacity after surgery.29

Nutritional Intervention

Regardless of baseline nutritional status, surgical trauma induces a stress response that increases oxygen consumption, mobilizes energy reserves, and promotes protein catabolism, ultimately resulting in skeletal muscle wasting.1 Therefore, ERAS programs recommend pre-operative carbohydrate loading to minimize the catabolic influence of the surgical stress response.6

Five studies (three randomized controlled trials, one systematic review, and one cohort study) were identified for physical interventions before surgery in our literature review and are summarized in this section. A recent Cochrane systematic review concluded that pre-operative carbohydrate treatment compared with placebo or fasting reduces the length of hospital stay (0.30 days, 95% CI 0.56 to 0.04) in patients undergoing elective surgery (abdominal, orthopedic, cardiac, and thyroidectomy), although it has no significant effect on post-operative complication rates.30

Patients who are malnourished pre-operatively have a greater risk of morbidity and mortality and prolonged hospital stay.31 Nutritional intervention before surgery is particularly relevant in those patients. Importantly, malnutrition and cachexia are common in patients undergoing cancer surgery due to neoplastic disease, chronic inflammatory state, alimentary tract dysfunction, or psychological disorders such as low mood and stress-related anorexia.32 Jie et al published an observational study showing that post-operative complication rates before abdominal surgery decreased in malnourished patients who received adequate pre-operative nutrition.33 Studies in patients with colorectal cancer resection showed no significant beneficial reduction in post-operative complications following nutritional supplementation,11 34 although patients who received whey protein supplementation 4 weeks before surgery had a mean improvement in functional walking capacity.11 A prospective randomized study in non-malnourished patients undergoing abdominal cancer surgery showed that patients who received nutritional supplementation for 14 days before surgery significantly reduced the number and severity of post-operative complications. Moreover, laboratory parameters decreased in the control group, while in the nutritional supplementation group they were stable (albumin and total protein) or raised (transferrin and total lymphocyte count) after surgery.35

Although nutritional supplementation could be beneficial for all surgical patients, malnourished patients should be identified early during pre-operative evaluation to enable appropriate nutritional intervention. To this end, there are many nutrition screening tools designed to detect malnutrition, such as the Malnutrition Universal Screening Tool (MUST), Nutrition Risk Index, and Nutrition Risk Screening. MUST is described as a simple and quick method that is easy to use by healthcare professionals, with high validity for early detection of malnutrition and guide for intervention.36

Lastly, it is important to take into account that nutritional supplements act synergistically with exercise by allowing successful muscle gain during physical exercise and optimizing its effect.37

Psychological Intervention

The pre-operative period is an uncertain time for patients, who usually experience anxiety for a variety of reasons including diagnosis (ie, cancer), surgery, and possible complications. Six studies (three randomized controlled trials, two systematic reviews, and one cohort study) were identified for psychological interventions before surgery and are summarized in this section.

Patients who present with pre-operative psychological distress may have a worse surgical recovery and a higher risk of mortality.38 39 In agreement with that, some prehabilitation programs include psychological interventions before surgery. The psychological status of patients is usually assessed with the Hospital Anxiety and Depression Scale (HADS).40

The effect of psychological intervention in a prehabilitation program is controversial. Barberan-Garcia et al evaluated baseline and pre-operative HADS scores in a randomized blinded controlled trial of patients undergoing major abdominal surgery without improvement in psychological status. The intervention group underwent a personalized prehabilitation program based on motivational interview and physical activity, with absence of a specific psychological intervention.15 Another randomized study in patients undergoing colorectal resection for cancer compared a 4-week trimodal prehabilitation program to a control group (which received the same interventions but only immediately after surgery), and found no significant differences in the HADS score. The psychological intervention consisted of training by a psychologist on relaxation exercises that could be performed at home.25

In contrast, a similar psychological intervention significantly reduced the HADS score during the pre-operative period of time, although without reaching a clinically relevant difference. In this study, the control group was assessed only immediately before surgery, so changes during the pre-operative period could not be evaluated.7 Moreover, a Cochrane review about the effect of psychological intervention on post-operative outcomes suggested that emotional support may be beneficial for post-operative pain, behavioral recovery, and length of stay.41 Thus, psychological intervention in a prehabilitation program could be important to improve surgical recovery. Nevertheless, its effect on prehabilitation programs needs further assessment to identify which method is more effective and to promote best compliance.

Lastly, it is important to consider that the addition of a psychological intervention in a prehabilitation program could also help to reinforce patient motivation to follow physical exercise and nutritional interventions. Conversely, physical exercise has been associated with an improvement of anxiety and depressive symptoms.42 Moreover, although anxious patients showed a greater improvement in functional capacity during the prehabilitation period, they were ultimately less likely to recover to baseline after surgery.43

Medical Optimization

The target of medical optimization is to identify pre-existing comorbidities and manage them before surgery. Measures to achieve medical optimization in our program are shown in Table 1. It is strongly recommended to stop tobacco and alcohol consumption. Smokers can enroll in a hospital pulmonology program that consists of behavioral support and nicotine replacement therapy, if needed. Pre-operative screening for anemia is evaluated through a blood test in pre-operative assessment. Pre-operative intravenous or oral iron is recommended if hemoglobin levels are <11 g/dL. During pre-operative evaluation, other comorbidities such as hypertension, chronic obstructive pulmonary disease, chronic heart disease, and diabetes are managed to gain optimal control before surgery. In addition, the G-8 scale, a geriatric screening scale for frailty, is used to evaluate patients older than 70 years. Patients with a positive G-8 score (≤14 points) are referred to a geriatrician. In the baseline evaluation we explore the social environment and request individualized support from a social assistant, if necessary.

Physical Intervention

Functional exercise capacity is evaluated with the 6-MWT test and VO₂max is calculated. Then, an exercise plan is prescribed based on these results (Table 2). The 6-MWT is performed at baseline, before surgery, and 8 weeks after surgery. In addition, all patients are asked to record their physical activity in a diary, and are encouraged to remain as active as possible to continue improving their own post-operative condition after discharge. Patients with VO₂max <12 mL/kg/min undergo a supervised physical therapy program by physiotherapists. Patients with VO₂max ≥12 mL/kg/min are further stratified and we prescribe a home-based exercise program consisting of daily training sessions that include aerobic, strength, flexibility, and respiratory exercises at different intensities. Exercise is prescribed following the guidelines of the American College of Sports Medicine.50 Additionally, all patients are prescribed inspiratory exercise through inspiratory muscle training. This consists of 10 min sessions every 8 hours using an inspiratory threshold-loading device with maximal inspiratory muscle strength. After surgery, patients are encouraged to start in-hospital exercise as soon as cleared for mobilization by the nursing staff as a part of ERAS program. At this point, and during their hospitalization, patients in more serious physical condition are able to review the exercise program with a physical therapist, in order to ensure that they are both confident and comfortable performing the exercises after discharge.

Nutritional Intervention

Nutritional therapy may involve screening tools and pre-operative dietary advice. We evaluate nutritional status with body mass index, laboratory parameters, and MUST score. The MUST score uses three independent parameters to determine the overall risk of malnutrition: 0-low, 1-medium, and ≥2 high risk of malnutrition. In addition to the MUST score, serum albumin is assessed at baseline, pre-operative, and at 8 weeks after surgery. Depending on the baseline nutritional parameters, we recommend oral nutritional supplements. In severely malnourished patients (MUST ≥2 or albumin <3 g/dL), a dietitian creates an individual dietary plan (Table 3). All patients receive a nutritional education program involving food selection and meal planning patterns including a list of home-made recipes of protein supplements adapted to diabetic patients, if necessary. All patients are instructed to take these oral protein supplements daily 30 min after exercise training to enhance muscle hypertrophy. In addition, all patients receive 50 g of a carbohydrate-loaded drink 2 hours before surgery and the anesthesiologist prevents their dehydration during surgery by following ERAS guidelines. After surgery, patients are encouraged to start in-hospital oral feeding as soon as possible. All patients receive oral protein supplements during their hospitalization. A dietitian re-assesses malnourished patients during their hospital stay and recommends a dietary plan during the hospitalization and at discharge. All patients are asked to keep a daily diary of food intake to evaluate their compliance with nutritional recommendations.

Psychological Intervention

The psychological status of patients is assessed through the HADS screening test which includes anxiety and depression subscales. Each scale has seven items scored 0 to 3, and the total score ranges from 0 to 21, with higher scores indicating worse affective or mood disorders. The HADS test is performed at baseline, before surgery, and at 8 weeks after surgery. Patients whose HADS score is ≤7 are prescribed anxiety reduction techniques such as relaxation and breathing exercises, to be performed at home for 20 min after lunch and before going to bed. Patients whose score is >7 are referred to a psychologist, who prescribes personalized treatment and techniques to alleviate pre-operative anxiety or depression symptoms. A psychologist supports these patients during their hospital stay and at discharge (Table 4). In addition, once a week all patients are encouraged to attend a free supervised session of mindfulness at the hospital.