Most of the seven billion people in this world suffer from malnutrition. Half do not have enough to eat and the rest of us eat too much.
Introduction
In elderly patients undergoing surgery, optimization of fluid balance and nutritional state is of the utmost importance for improving outcome, reducing postoperative complications, length of hospital stay (LOS), rehabilitation and convalescence. Older individuals are at nutritional risk or malnourished – mostly because of coexisting diseases coupled with physiological changes due to aging – and maintaining a high index of suspicion for pre-existing nutritional deficiencies is a fundamental issue. Malnutrition predisposes to morbidity and mortality, and up to 71% of older hospitalized patients are at nutritional risk or malnourished (de Luis and Lopez Guzman 2006). Moreover, undernutrition can develop further while in the hospital, making perioperative nutritional support an important therapeutic aspect of the management of these patients, provided that nutrition is tailored to their individual needs. When detected before elective major surgery, a preoperative nutritional support should be evaluated as a part of the prehabilitation process (see Chapter 12).
Nutrition support is indicated in patients with severe illness and increased nutritional requirements, or who are severely undernourished, or in patients with diseases of light/moderate severity and certain degrees of undernutrition, with the aim of improving the course and outcome of the illness. The rationale for nutritional support in perioperative care is that correcting nutritional deficits can attenuate the metabolic response to surgical stress, as it both prevents oxidative cellular injury and favourably modulates immune response, so contributing to decrease the rate of postoperative complications.
Common Nutritional Deficits in the Elderly
Good nutrition involves the adequate intake/absorption of macronutrients (carbohydrates, fats and proteins), as well as micronutrients (vitamins, minerals, antioxidants and fiber).
Older adults are at risk for nutrient deficiencies for a wide variety of reasons: loss of appetite and sense of taste and smell, poorly fitting dentures (chewing/swallowing difficulties), mucosal lesions, immobility, financial factors, impaired physiological function or use of medications decreasing the ability to absorb nutrients or increased nutrient requirements (malignancy). Frailty, functional dependence, depression, cognitive impairment, dementia and multimorbidity are often associated with poor nutritional status.
Age-related changes in body composition (see Chapter 1) result in a reduction in lean body mass, a declining bone density, an increase in total body fat and a decrease in total body water; furthermore, fasting blood glucose levels tend to increase, as the ability to metabolize carbohydrates declines with age. In spite of this, nutrition-related problems are often overlooked in geriatric patients (Volkert et al. 2010). Weight loss, by itself – especially if it is not volitional – is predictive of mortality, and is clinically significant with the following parameters: ≥2% decrease in baseline body weight in one month, ≥5% in three months, or ≥10% decrease in six months. Involuntary weight loss is driven by inadequate dietary intake, loss of appetite, disuse or muscle atrophy (sarcopenia), inflammatory effects of disease (cachexia) or a combination of these factors. Micronutrient deficiencies are often common in elderly people. Subclinical deficiencies in water-soluble vitamins (vitamin B12, vitamin B6, folate, ascorbic acid), as well as low vitamin D levels and increased demands for calcium, should be expected in geriatric patients.
In older adults, the prevalence of malnutrition is 5–10% of independently living individuals, 30–60% of institutionalized patients, 35–65% of hospitalized patients, reaching almost 80% in patients living in nursing homes. Hospitalized patients require higher dietary protein intake beyond the augmented needs induced by age and immobility, because of surgery, sepsis, bone fractures and pronounced losses due to the illness requiring hospitalization (ASPEN 2002). Because of the increased requirements, special attention has been placed on the need for perioperative nutritional support in geriatric patients, and great effort should be devoted to this achievement.
Nutritional Screening
Evaluation of nutritional status in older persons should not require special training or qualifications, and should be quick and practical. The Academy of Nutrition and Dietetics, and the American Society for Parenteral and Enteral Nutrition suggest that the presence of two or more of the following six characteristics indicate malnutrition: (1) insufficient energy intake; (2) weight loss; (3) loss of muscle mass; (4) loss of subcutaneous fat; (5) localized or generalized fluid accumulation that may mask weight loss and (6) diminished functional status, as measured by handgrip strength (White et al. 2012). When a patient has been categorized as malnourished or at risk of developing malnutrition, nutritional assessment is indicated, with the purpose of influencing the outcome by means of nutritional treatment.
A gold standard for the diagnosis of malnutrition does not exist, and many screening and assessment tools are used, such as the Mini Nutritional Assessment (MNA), the Malnutrition Universal Screening Tool (MUST), the Short Nutritional Assessment Questionnaire (SNAQ), the Malnutrition Screening Tool (MST), and the Subjective Global Assessment (SGA) (Bauer et al, 2010). MNA is a validated and quick screening tool that is frequently used in Comprehensive Geriatric Assessment and in the preoperative setting. A review by Guygoz (2006) confirmed its ability to detect the risk of malnutrition before severe change in weight or serum proteins occur and suggests that it should be adopted as a part of a minimum data set for nutritional interventions.
Since communication with older patients may be difficult, the Nutritional Risk Screening (NRS-2002), which does not rely on patient cooperation, may be regarded as the preferred screening tool for older hospitalized patients. The NRS-2002 is recommended by the European Society of Parenteral and Enteral Nutrition to detect the presence of undernutrition and the risk of developing undernutrition in the hospital setting, and has been successfully tested (Sorensen et al. 2008).
Table 13.1 shows the NRS-2002 screening system. Patients are scored in each of the two components: (1) assessment for baseline undernutrition and (2) an estimate of disease severity, according to whether they are absent, mild, moderate or severe, giving a total score 0–6 (+1 for patients >70 years old). Patients with a total score ≥3 are classified as nutritionally at risk. Undernutrition is estimated using three variables: body mass index (BMI) = weight (kg) / height (m2), recent percentage weight loss and change in food intake. Disease severity ranges from a score of 0 (for those with chronic illnesses or a hip fracture) to 3 (for those in the ICU with an APACHE score of 10).
| Impaired nutritional status | Severity of disease (= increase in requirements) | ||||
|---|---|---|---|---|---|
| Absent | 0 | Normal nutritional status | Absent | 0 | Normal nutritional requirements |
| Mild | 1 | Weight loss >5% in 3 months | Mild | 1 | Hip fracture |
| or | Chronic patients, especially with acute complications: cirrhosis, COPD, chronic hemodialysis, diabetes, oncology | ||||
| Food intake below 50–75% of normal requirement in the preceding week | |||||
| Moderate | 2 | Weight loss >5% in 2 months | Moderate | 2 | Major abdominal surgery |
| or | Stroke | ||||
| BMI 18.5–20.5 kg/m2 + impaired general condition | Severe pneumonia | ||||
| or | Hematologic malignancy | ||||
| Food intake 25–50% of normal requirement in preceding week | |||||
| Severe | 3 | Weight loss >5% in 1 month (> 15% in 3 months) | Severe | 3 | Head injury |
| or | Bone marrow transplantation | ||||
| BMI <18.5 kg/m2 + impaired general condition | Intensive care patients (APACHE > 10) | ||||
| or | |||||
| Food intake 0–25% of normal requirement in preceding week | |||||
| Score | + | Score | = Total | ||
Calculate the total score:
1. Find score (0–3) for impaired nutritional status (only one: choose the variable with the highest score) and severity of disease (= increase in requirements)
2. Add the two scores (→ total score)
3. If age >70 years: add 1 to total score (age-adjusted score)
Score ≥ 3: the patient is nutritionally at risk and a nutritional care plan is indicated
Score <3: weekly rescreening of the patient. If the patient is scheduled for a major operation, a preventive nutritional care plan is considered, to avoid the associated risk status.
COPD = chronic obstructive pulmonary disease. APACHE = Acute Physiology and Chronic Health Evaluation
According to the results of the latest Cochrane analysis on energy and protein supplementation in older persons, it is predominantly the malnourished patient who mostly benefits from nutritional therapy (Milne et al. 2009). Several studies in patients nutritionally at risk showed that they have an increased likelihood of a positive effect of nutritional intervention (Avenell and Handoll 2004), and the screening system may discriminate patients who will benefit from nutritional support.
Metabolic Rate and Energy Requirements
Age-related changes in body composition result in a slight decline in lean body mass that is usually more dramatic after the age of 60. Consequently, basal metabolism or energy requirements for the elderly diminish by about 100 kcal/day per decade. Determination of requirements in the clinical setting remains difficult, and most clinicians use simplistic weight-based predictive equations (in presence of edema or anasarca, usual body weight should be used): Energy requirements = 25–30 kcal/kg/day; Protein requirements = 1.2–2.0 g/kg/day (a high-protein regimen should be applied carefully in patients with renal or hepatic dysfunction). Although these equations are less accurate in obese and underweight patients, the advantage of using them, over other predictive equations, is simplicity.
Protein appears to be the most important macronutrient for healing wounds, supporting immune function and maintaining lean body mass. Protein requirements are proportionately higher than energy requirements in patients at nutritional risk or malnourished, and routine enteral formulations (which have a high non-protein calorie-to-nitrogen ratio) do not easily meet the increased requirements.
Appropriate nutrition should be offered by the oral route, using food with or without special supplements. When this is insufficient, enteral tube feeding can be used. In patients for whom enteral feeding is contraindicated or unsuccessful, parenteral nutrition may be required.
Perioperative Nutritional Management
Nutritional support refers to enteral or parenteral provision of calories, protein, electrolytes, vitamins, minerals, trace elements and fluids. Patients undergoing elective surgery should be managed with a multimodal approach that includes evidence-based interventions to optimize nutritional status, postponing surgery whenever possible. In geriatric patients, nutrition management should take into account the aging physiologic changes, cognitive status, poly-pharmacy and potential drug interactions, hydration status and prognosis. Restoring electrolytes, maintenance of normal glucose levels, interruption of high-risk medication, early mobilization and control of severe pain are highly recommended as part of a multimodal approach.
The target of nutritional treatment should be to optimize fluid intake and ensure sufficient energy and protein intake orally. Simple interventions, such as getting the patient out of bed at mealtimes and providing assistance with feeding, can improve nutritional intake during hospitalization. Restricted diets are not required for older patients, who should always be allowed to eat, unless medically required to maintain “nothing by mouth” (NPO).
There is no role for routine nutritional support in patients undergoing major surgery, however recent studies define the groups of patients who benefit from perioperative nutritional support, particularly those with prior malnutrition (Milne et al. 2009). Current European Guidelines suggest nutritional support for 7–14 days prior to major surgery, enteral or parenteral, according to the level of undernutrition and/or feeding possibilities, for patients at severe nutritional risk (Braga et al. 2009).
Basically, nutritional care before and after surgery should address the following goals:
avoid insufficient/inadequate food intake
reduce metabolic alterations induced by stress response to surgery (altered glucose metabolism, accelerated muscle catabolism and increased amino-acid requirements)
minimize inflammatory response related to surgical aggression and/or cancer.
Nutritional Prehabilitation
Impaired nutritional status is a modifiable risk factor for postoperative complications, mostly after abdominal surgery (Jie et al. 2012). Together with physical, emotional, medical and pharmacological conditions, it should be optimized preoperatively with the aim of improving functional capacity and impacting on perioperative morbidity and mortality.
A prehabilitation nutritional care plan starts with nutritional counseling, where patient’s food preferences and routine food intake are evaluated. A nutritional plan is then defined based on nutritional requirements, preferred food, biological indices (glucose, creatinine etc.), medical history and clinical status. Nutritional intervention consists of optimization of protein intake to achieve a daily intake of 1.2–1.5 g/kg/day, divided into three meals and supplemented with whey protein in powder form (10–30 g/day), which are rapidly digested, rich in essential amino acids, including leucine, and have important immune-modulating properties.
Preoperative Fasting
Fasting before general anesthesia aims at reducing the volume and acidity of the stomach contents, thus reducing the risk of regurgitation/aspiration. There is no evidence that clear fluids given 2–3 h preoperatively put the patients at higher risk of regurgitation (except in emergency surgery or in the presence of delayed gastric emptying). Over the last decade, many anesthesia societies have changed preoperative fasting guidelines from the standard “NPO from midnight” approach, and now recommend free intake of clear fluids up to a few hours before anesthesia (Brady et al. 2003). Moreover, it has been shown that, compared to an overnight fast, preoperative carbohydrate-rich beverage loading the night before and 2 h before surgery does not increase the risk of aspiration, reduces preoperative hunger and anxiety, attenuates the development of insulin resistance, preserves skeletal muscle mass and improves the patient’s preoperative wellbeing (Brady et al. 2003). The preoperative use of carbohydrate-rich beverage loading forms part of the Enhanced Recovery After Surgery (ERAS) protocols (Lassen et al. 2009). For patients who are excluded from the liberal fasting guidelines, I.V. glucose with or without insulin has been shown to have the same effect.
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