Nutrition in the Geriatric Surgical Patient
The elderly population is particularly vulnerable to malnutrition due to a number of physiologic, psychologic, and socioeconomic changes associated with aging. Diagnosis is challenging and a number of screening modalities have been described. Reliance upon biochemical testing (albumin and prealbumin) alone is not recommended. Multiple screening tools such as Mini Nutritional Assessment (MNA), Nutrition Risk Index (NRI), Malnutrition Universal Screening Tool (MUST), and Nutritional Risk Screening-2002 (NRS-2002) have varying degrees of accuracy. Because malnutrition and “at risk for malnutrition” are strongly predictive of poor clinical outcomes, intervention is recommended, though reversal of malnutrition in the elderly is particularly difficult after significant lean body mass has been lost. Prehabilitation with nutrition and exercise begins in the preoperative stage, continuing through the perioperative period, and continues beyond the immediate postoperative period.
KeywordsMalnutrition Nutritional risk Mini Nutritional Assessment Anoxexia of aging Enteral nutrition Parenteral nutrition Prehabilitation
What tools would you use to screen this patient for malnutrition?
What interventions can you implement to optimize this patient for surgery?
By the year 2030, one in five people in the United States will be over the age of 65. The elderly population will continue to increase to 88.5 million by 2050 – more than double what it was at the time of the 2010 census . This change translates into an increase in surgical volume in the elderly as well. In 2007, one-third of all inpatient surgical procedures were performed on elderly patients, and in the next few years, that number is projected to double [2, 3].
The elderly population is particularly vulnerable to malnutrition . The prevalence of malnutrition in the elderly reported in the literature is variable, with rates as high as 60% [4, 5]. This inconsistency can be attributed to a range of geographic locations and varying methods of assessment . Using a pooled analysis of 4,000 elderly patients from 12 countries on five continents treated in multiple settings evaluated with only one assessment tool, the overall prevalence of malnutrition was 23%. When further categorized by treatment setting, the prevalence was highest in rehabilitation centers and hospitals (51% and 39% respectively), and was lower in nursing homes and in the community (14% and 6%) . The prevalence of patients “at risk of malnutrition” was even higher at 46% – meaning two-thirds of the entire study population was either at risk of malnutrition or already identified as malnourished .
Malnutrition has serious consequences in the elderly. Malnourished elderly patients (as defined by a body-mass index (BMI) of <20 kg/m2) have a 1-year mortality rate approaching 50% . In order to improve care, including surgical care of the elderly, it is imperative that malnutrion be recognized and addressed appropriately.
Factors Contributing to Geriatric Malnutrition
Between the ages of 20 and 70, mean energy (calorie) intake decreases by 1,062 kcal/day in men and 481 kcal/day in women . On average, men over age 65 in the USA were shown to lose 0.5% of their body weight each year . There are a number of changes associated with aging – physiologic, psychologic, and socioeconomic – that predispose this population to under-nutrition.
Changes to appetite, taste, olfactory, and visual acuity, chronic disease, physical disability, and dentition can impact food choice and dietary intake. Appetite declines with age, with elderly persons eating smaller meals, eating fewer snacks between meals, and feeling full more rapidly. This trend is referred to as the “anorexia of aging ” . The processes present in younger people that impact appetite and correct for over- or undernutrition are not as effective in older people. One study underfed healthy community-dwelling young (mean age 24) and old men (mean age 70) and then documented the responses when they were allowed to eat freely again. The young men over-ate above their baseline consumption to compensate and quickly regained weight, while the older men only returned to their baseline dietary intake and did not regain lost weight . This study suggests an inability among the elderly to quickly rebound from acute undernutrition, similar to the type of acute insult that occurs with a major operation. These patients take longer to regain lost weight and remain malnourished for a prolonged period.
Also contributing to a decline in appetite with aging is deterioration of the senses of taste and smell. The threshold to detect tastes increases with age, with salt being the most difficult to taste; however these changes are variable and the extent of the impact on energy consumption is unproven . The sense of smell is particularly important to stimulate interest in food. This sense, however, deterioriates after age 50 , and the consumption of a nutritionally balanced diet is often negatively impacted by removing this stimulus. Additionally, the process of obtaining nutrients from food – from chewing, to slowed absorption – is greatly impaired in the elderly. Dentition alone can change diet and limit the variety and amount of food able to be consumed, particularly protein intake .
Even the GI tract itself affects the process of obtaining nutrition. For instance, aging results in impaired gastric emptying and early satiety due to an increase of nitrous oxide in the fundus that occurs with aging . Other comorbidities and chronic medical conditions that occur with aging can also contribute to malnutrition. For instance, diseases that limit mobility either by deformity (such as rheumatoid arthritis), or by limited functional capacity (such as respiratory diseases) can cause malnutrition by impairing feeding, shopping, and food preparation. Chronic medical conditions also require the use of prescription medications, many of which have adverse effects that can limit nutrition. These medications can have a myriad of side effects, including anorexia, nausea, diarrhea, and early satiety among other gastrointestinal symptoms ([16, 17]. Often, with a large number of medications prescribed, it is difficult to parse out symptoms caused by drug interactions.
Body composition changes with age, resulting in an increase in fat and decrease in lean body mass such as skeletal muscle . Up to 3 kg of fat-free muscle mass is lost each decade after 50 years of age . The change in body composition is attributed to several factors, including decreased physical activity, reduced growth hormone and sex hormone levels, and changes in metabolic rate. Testosterone and other androgens decrease with age, contributing to sarcopenia . Additonally, decreases in growth hormone and insulin-like growth factor 1 (IGF-1) affect age-related changes in appetite and food intake .
Psychological variables that impact food choice and nutrition include loneliness, bereavement, food likes/dislikes, and mental awareness . Depression occurs in 2–10% of elderly people in the community . In the elderly population, this condition tends to be associated with decreased appetite, loss of body weight, and subsequent malnutrition. While only seen in about 60% of younger adults with depression, weight-loss is noted to be a symptom of depression in nearly all elderly patients . Treating depression has been reported as an effective way of promoting weight gain . Additionally, the elderly tend to live alone and there is an association between loneliness and decreased appetite in the elderly. When not eating alone, older people will eat significantly more . Finally, the prevalence of dementia increases with age, often affecting feeding behaviors and leading to weight loss .
Socioeconomic factors also impact nutrition in the elderly, as this patient population is often in retirement with a lower or fixed income. Expenses for treatment of the chronic medical conditions associated with aging, such as prescription medication costs, can further limit income available for purchasing nutritious food . Low income can cause “food insecurity,” a state where people cannot afford nutritious food, leading to malnutrition . Social factors such as convenience of cooking facilities, distance to food stores, availability of transportation, and access to preferred foods also impact nutrition. When examining activities of daily living, 12% of older persons required help with managing finances, 29% needed help with shopping, and 16% could not prepare food independently . All of these factors contribute to the overall anorexia of aging that makes the elderly population especially vulnerable to malnutrition and its consequences.
Nutritional Assessment of Geriatric Patients
History and Physical Exam
In order to intervene appropriately to optimize nutrition in elderly patients, malnutrition must first be identified. There is a vast array of nutritional assessment strategies that have been employed clinically for this patient population, beginning simply with history and physical exam. These traditional means rely on the patient or caregiver reporting symptoms such as a history of weight loss or changes in diet and detecting physical findings associated with malnutrition such as muscle wasting or edema. The clinician should always begin with history and physical before proceeding to more sophisticated screening tools.
Subjective Global Assessment
One assessment method that formalizes and incorporates the history and physical exam is the subjective global assessment (SGA), introduced by Detsky in 1987 . The SGA includes functional capacity and the clinican’s overall impression of the patient’s status which they designate as “normal,” “mildly malnourished,” or “significantly malnourished” . To make that subjective judgment, clinicians assess for a history of weight loss and poor dietary intake and loss of subcutaneous tissue and muscle wasting on physical exam. The SGA does not include laboratory testing. In validation studies, Detsky et al. demonstrated a sensitivity of 82% and specificity of 72% when using the SGA to predict infection secondary to poor nutritional status – better than six other methods including several laboratory tests and other nutritional indexes .
Despite the high level of sensitivity and specificity shown by Detsky, the successful use of the SGA to predict malnutrion is limited by several factors. First, it is most effective when performed by clinicans experienced with the assessment. In additional validity testing in other clinicians, the same level of sensitivy was difficult to replicate. For instance, one study compared the SGA form completed by two independent clinicians to a combination of anthropometry and measurement of serum protein. The two observers had an agreement level of 77.8% and there was significant variability between the two observers in predicting malnutrition (82% vs. 66%) . These studies suggest that SGA is a reliable assessment tool in the hands of experienced clinicians. Similarly, a review of the literature reveals that the SGA performs similarly to traditional methods of determining nutritional status, such as laboratory testing and anthropometry, but concludes that alternative nutritional assessment tools, which will be discussed later in this chapter, are more reliable in detecting malnutrition than the SGA . Another limitation of this method is that the physical signs of muscle wasting and subcutaneous fat loss emphasized by the SGA are often late signs of malnutrition, making the SGA less useful in detecting early malnutrition and also less helpful in re-evaluating progress after interventions for malnutrition . While the SGA does provide a way to translate the history and physical exam into assigning a degree of malnutrition in the hands of an experienced clinician, it is not the ideal assessment tool.
In the past, the serum albumin level has been used to define malnutrition under the assumption that albumin level is proportional to the severity of malnutrition. Hypoalbuminemia was presumed to represent a deficit that can be corrected by increasing dietary protein intake. Although this association may be true in a purely protein deficient state, such as Kwashiorkor, in general, the relationship between albumin and malnutrition is far more complex . Albumin levels are affected by many additional factors unrelated to nutrition status. Clinical factors that alter protein anabolism or catabolism including liver cirrhosis and certain drugs (such as steroids) likewise impact albumin levels .
Albumin production is limited in the setting of inflammation as protein synthesis shifts toward the production of cytokines and the protein is lost from the intravascular space to the interstitium [22, 27]. In this regard, it behaves as a negative acute phase reactant . Thus, in the inflamed state, the serum albumin level may be low even in well-nourished patients. The half-life of albumin is 18 days, yet the albumin level has been observed to decrease rapidly after hospital admission – too immediate a response to be explained by malnutrition alone.
In addition to the effects of various disease and inflammatory processes, aging itself is associated with a modest decline in serum albumin levels, with a decrease of 0.8 g/L per decade after age 60 [22, 28, 29]. Even recumbent posture has been reported to a decrease in albumin levels . With a multitude of influences, serum albumin lacks the sensitivity and specificity to be an accurate indicator of nutrition. However, albumin has been reported as an accurate predictor of mortality and overall health status [22, 24, 31]. A study of patients in a geriatric rehabilitation unit at a Veterans’ Affairs hospital reported that 3 months after discharge, albumin was the strongest predictor of long-term mortality. Patients with albumin less than 35 g/L had 2.6 times greater mortality than those with serum albumin levels above 40 g/L . Subsequent studies from the same group indicate that inflammation at the subclinical level may contribute to the lower albumin levels . At the present time, the body of knowledge suggests that albumin is a valuable biomarker of severity of illness and predictive of perioperative complications, including mortality, prior to elective major surgery . This predictive ability is diminshed in the setting of critical illness [34, 35, 36]. However, the connection between albumin and nutrition is tenuous at best and likely confounded by comorbid illness [24, 26, 37]. There has been no convincing evidence that aggressive nutritional therapy (independent of treating the comorbid illness) directly increases serum albumin, and that improved serum albumin resulting from nutritional optimization leads to improved outcomes.
Transthyretin (Prealbumin) and C-Reactive Protein
Like albumin, prealbumin (also known as transthyretin (TTR)) has been used as a metric of protein malnutrition since the 1970s . Despite its misleading name, prealbumin is not a precursor to albumin. Originally named in reference to its relationship to albumin on a protein electrophoresis plate, prealbumin plays a variety of roles including thyroxin transport and vitamin A transport through formation of a complex with retinol-binding protein [39, 40]. The normal range of prealbumin is reported as 150–350 mg/L and the half-life of prealbumin is 2 days. A consensus statement regarding the use of prealbumin in nutrition evaluation was issued in 1995. Per this statement, a level between 50 and 109 mg/L indicated significant risk of malnutrition and a level of less than 50 mg/L was an indicator of poor prognosis . Furthermore, an increase of less than 40 mg/L within 8 days despite providing 100% of protein need is indicative of need for further intervention and also of poor outcomes . However, factors other than nutrition status alone can also impact prealbumin levels.
Like albumin, the use of serum prealbumin is complicated by the fact that levels also change rapidly when protein synthesis shifts toward acute-phase proteins in the setting of systemic inflammation [42, 43, 44, 45, 46]. Because prealbumin also acts as a negative acute phase reactant, there has been a movement toward including C-reactive protein (CRP) in acute metabolic panels to assess whether changes in prealbumin are due to an inflammatory process secondary to acute illness or by malnutrition [45, 47].
CRP levels respond quickly to tissue injury – 4–6 h faster than other acute phase reactants, though aging has not been shown to affect measured values . CRP will decrease within 3–5 days after trauma or the resolution of sepsis as other proteins like albumin and prealbumin begin to increase. Based on this relationship, a Prognostic Inflammatory and Nutritional Index (PINI) has been created to assess the severity of disease processes and predict survival. In a study of patients in an acute geriatric unit, a PINI score of greater than or equal to 25 was predictive of in-hospital mortality. Hypoalbuminemia, on the other hand (less than or equal to 30 g/L), was associated with disability but did not predict mortality .
Additional studies provide similar evidence to support the use of prealbumin combined with CRP to assess for protein-calorie malnutrition. In a study of Belgian geriatric units, prealbumin was measured at the third day of admission and at discharge. A prealbumin level of 170 mg/L was considered to represent increased risk of malnutrition, and patients with a prealbumin concentration of less than 200 mg/L were provided with caloric supplementation. The patients receiving supplementation were admitted with lower prealbumin and higher CRP levels than patients not receiving supplementation. Those patients were then discharged with higher prealbumin and lower CRP levels than the group without supplementation. Although prealbumin levels do appear to reflect dietary repletion, the levels are not specific, as severity of illness and inflammation influence the same markers . Similarly, Mears has reported on the outcomes of a malnutrition screening program that used prealbumin levels for patient assessment at the time of hospital admission and monitoring throughout patients’ hospitalization . In that study, patient care improved with early and accurate identification of patients with protein-calorie malnutrition. Less invasive and less expensive methods of nutritional supplementation were required due to the early diagnosis and length of hospital stay and readmission rates were decreased. Not only was patient care improved, but these effects, along with the ability to add the diagnosis as a comorbid condition for Medicare reimbursement, also led to a significant financial benefit to the hospital .
Prealbumin-based malnutrition screening has been shown to identify more patients as being malnourished than albumin screening and is able to provide early and correct identification of patients at risk of malnutrition [47, 49, 50]. Another positive aspect of prealbumin-based screening is that it does not change drastically with increasing age in healthy individuals, unlike albumin levels, which change significantly . Although imperfect, the sensitivity of prealbumin in identifying malnutrition and the minimal change with age make it a useful marker in nutritional assessment in the elderly in the uninflamed state. It is important to emphasize, however, that the use of serum protein markers, including albumin and prealbumin, is not validated in critical illness and their use in this setting is discouraged by the Society of Critical Care Medicine (SCCM) and the American Society of Parenteral and Enteral Nutrition (A.S.P.E.N.) .
Other Biochemical Markers
While not commonly used in clinical practice, there are additional biochemical markers that have been described as indicators of malnutrion. As part of the vitamin A transport complex formed with prealbumin, retinol-binding protein (RBP) is also a marker of nutrition . Levels of prealbumin and RBP are comparable except in vitamin A deficiency. RBP remains stored within the liver until vitamin A levels normalize. Like prealbumin, it has a short half-life (12 h) and decreases with liver disease, stress, and inflammation. RBP levels are increased in the setting of renal failure . Also, levels do change with age, and the mean and median levels for healthy nonagenarians and centenarians are overall lower in men and higher in women .
Insulin Growth Factor-I (IGF-I), like prealbumin and RBP, is a protein with a short half-life (2–4 h) and was found to fall during periods of protein malnutrition and rise with refeeding . Baseline levels begin to decrease when patients are in their fifth decade and are reduced by 35–60% by their tenth decade. Levels are affected by renal and hepatic failure, autoimmune disease, inflammation, and stress . IGF-I predicts “life-threatening” and “life-threatening infectious” complications in patients over the age of 76 and correlate with other measurements of nutrition .
Fibronectin is a glycoprotein produced by endothelial cells, fibroblasts, macrophages, and the liver. It has been explored as a nutritional marker because of its short half-life (4 h). Levels were noted to fall in the setting of starvation within 2 days and return to normal within 5 days of refeeding, prompting the possibility of use as a marker of protein malnutrition . Because it is not produced solely in the liver, fibronectin is less influenced by liver disease. However, fibronectin levels are impacted by burns, infections, and shock as well as the lipid content in some enteral feeding formulas . While plasma fibronectin concentration does increase within a week of nutritional therapy initiation, it does not seem to change significantly thereafter. It also does not correlate with other measures of nutrition and is not predictive of patient outcomes .
Total lymphocyte count (TLC) has also been suggested as a marker of malnutriton. Malnutrition was observed to be associated with a decrease in TLC and a TLC of less than 1,500/mm3 was associated with a four-fold increase in mortality . One study compared TLC to anthropometry measurements, serum albumin, total cholesterol levels, and total score on the mininutritional assessment (MNA) in patients age 65–95. The authors found that there was no difference among the patient groups (grouped as “severely low,” “low,” or “normal” TLC) in relation to the other measurements of nutrition. TLC did decrease with increased age, but did not change with other nutritional markers . TLC does not appear to be an appropriate or accurate marker of nutrition in the elderly population.
Body Composition and Anthropometric Measures
The 2012 consensus statement on malnutrition from A.S.P.E.N. has included the loss of muscle mass as part of its definition of malnutrition, bringing focus to the assessment of muscle loss . Physical exam alone to subjectively assess muscle mass and muscle loss is an unreliable method. Methods of body composition and anthropometric measures have therefore been developed to better estimate lean muscle mass and assess nutritional status.
The hydration constant is less reliable in the settings where hydration is variable and in obesity. An alternative calculation to TBW involves lean body mass (LBM) or lean soft tissue (LST) which represents all of FFM except bone and is measured by dual-energy X-ray absorptiometry (DXA) . DXA analyzes soft tissue overlying bone in vivo and works best in areas with well-defined bone such as the arms and legs where a sum of the lean soft-tissue mass of the arms and legs is used to define appendicular skeletal muscle .
Body cell mass (BCM) is another method of assessing body composition. BCM represents the total mass of oxygen-consuming and work-producing cells in the body, which is assumed to be the non-fat cellular portion of tissues like skeletal muscle, organ tissue, etc. Although BCM cannot be directly measured, there are several methods to estimate this compartment including neutron activiation analysis to determine total body nitrogen, total body potassium counting, and intracellular water measured by multiple dilution. All these calculations can be used to assess nutrition and nutrition interventions, though the varying levels of difficulty and expense lead to more common usage in research than clinical practice .
While body composition can be estimated mathematically, there are two bedside methods that can also be used estimate lean muscle mass. Bioimpedance and ultrasound assessment have been recommended by A.S.P.E.N. as direct methods of assessing body composition. Bioimpedence is measured by devices that produce an electric current at varying frequencies between electrodes placed in specified locations on the body . The flow of the current through the body is affected by body composition – electrolyte-rich blood and muscle conduct the current while fat and bone do not. The change in voltage as the current passes through the body’s tissue – the impedence – is detected by electrodes. This raw data is used to calculate body composition and estimate FFM based on the assumption that the body is comprised of five cylinders with constant cross-sectional area with patient’s height representing the length of the conductor . Devices to measure bioimpedence are not interchangeable – the equations used for the body composition calculations are specific to each device. The accuracy of bioimpedence measurements is dependent upon consistency in terms of set up such as electrode placement and body positioning as well as environmental factors such as temperature. Even biological changes in the patient can impact measurements; for instance electrolyte abnormalities or edema can alter resistence values .
An readily available option to estimate lean tissue at the bedside is ultrasonography. Ultrasound has recently been shown to predict FFM by taking the sum of measurements from several anatomic sites. Muscle thickness is measured and used to estimate total body FFM . This method is limited by operator experience and the subjective nature of interpreting the image and identifying muscle boundaries during measurement of muscle thickness. Also, muscle thickness changes depending on whether or not the muscle is contracted or relaxed. Ideally, measurements should be taken consistently with the patient in the supine position where muscles are more likely to be relaxed and compressible. The amount of pressure to apply while taking muscle thickness measurements has not yet been standardized; some studies advocating for maximal compression and others for no compression . One study reported that ultrasound measurements of the biceps, forearm, and midthigh muscle thickness FFM in patients with multiorgan failure correlated with DXA-determined estimates of FFM . Muscle thickness can also be used to predict outcomes as shown by a study from the University of Vienna in which quadriceps muscle thickness was shown to inversely correlate with length of stay in ICU patients . Despite the potential limitations, ultrasound-measured muscle thickness has been shown to be a low cost, noninvasive, and reliable method of estimating FFM.
In addition to the multiple direct bedside methods and calculations that exist to estimate body composition, an indirect means is also available in the form of anthropometry. One component of anthropometry is body mass index (BMI), which is calculated by dividing weight (kg) by height squared (m2). BMI alone, though, is imprecise in estimating lean body mass. Other anthropometric measurements include body circumference, which can be measured in multiple locations including midbrachial, calf, waist (measured midway between the most inferior rib and the iliac crest), and hip circumference (measured at the widest point of the buttock). Using the waist and hip measurements, a waist-to-hip ratio (WHR) can be calculated and used to determine visceral obesity and identify patients with increased mortality risk . However, increased relative risk of mortality is less pronounced in elderly patients over the age of 65 . The knee-heel length is also particularly relevant in the elderly population, where patients are often unable to stand upright for traditional height measurements. Stature height can then be predicted using equations developed from the third National Health and Nutrition Examination Survey (NHANES III) from the National Center for Health Statistics . Other measurements include subscapular, triceps, suprailiac, and thigh skinfold thickness measurements; however these require the use of calibrated calipers . Cross-sectional studies in various countries have provided normative reference data for age-, gender-, and disease-specific anthrompometric measurements [68, 71]. Anthropometric measurements can be applied to predict overall level of independence and function, as illustrated by a cross-sectional study of elderly patients receiving home care in Germany showing that patients requiring a higher level of care for their needs had lower anthropometric values .
Sarcopenia and Frailty
In 2006, a special interest group on nutrition in geriatrics was created within the Euopean Society for Clinical Nutrition and Metabolism (ESPEN). One of the concepts further defined by this special interest group was age-related sarcopenia – “the loss of muscle mass and muscle strength associated with aging” . Age-related sarcopenia is the result of intrinsic and extrinsic factors. Intrinsic changes with age include a decrease in anabolic hormones, increased muscle cell death, decreased number of alpha-motoneurons innervating skeletal muscle, and increased proinflammatory cytokines. External factors include decreased intake of protein and vitamin D .
In its most extreme form, sarcopenia can progress to frailty syndrome. Frailty is a lack of physiological reserve in multiple organ systems leading to increased vulnerability . Frailty is an independent predictor of 30-day morbidity and mortality and institutionalization after surgery and trauma [74, 76, 77, 78]. While there are multiple screening tools for frailty, the American Geriatrics Society/National Institute on Aging has adopted the frailty phenotype introduced by Fried et al . Screening for the frailty phenotype is based on five criteria: weight, grip strength, subjective fatigue, physical activity, and walking speed measurements .
In measures of anthropometrics and body composition, adequate protein nutrition is represented by fat-free mass (muscle). Since muscle mass is associated with muscle function, function is now being examined as an indicator of nutrition. Functional status can be measured in terms of voluntary and involuntary muscle function. The theory behind the use of function as a surrogate for nutrition status is that muscle structure changes with protein undernutrition leading to loss of contractile elements, increased muscle fatigue, and altered contraction patterns . Function measured with hand grip strength and quadriceps strength is also related to mortality, while muscle mass was not . Electrical stimulation testing can test involuntary muscle contraction and provide an objective measure of function, but more practical testing is available to assess voluntary function. Some commonly used measures are hand grip, knee extension, or hip flexion strength. Past studies have shown that handgrip dynamometry can accurately assess muscle function, which can then be correlated with nutritional status . Diminished handgrip strength is included in the A.S.P.E.N. consensus statement as a characteristic of malnutrition . The use of handgrip strength as a surrogate of nutrition is limited by a lack of consensus on measurement. Additionally, small changes in posture or hand position can change measured grip strength .
Nutritional Assessment Scoring Systems
The unidimensionality of most of the exams and laboratory values discussed up to this point limits their efficacy in identifying malnutrition in the complex geriatric population. For this reason, multifaceted assessment tools have been introduced into clinical practice.
Mini Nutritional Assessment
Of note, the MNA does not include biochemical markers as part of the assessment. During the development process, the sensitivity and specificity of the MNA without serum testing remained 96% and 98% . Exclusion of blood samples allows minimization of cost and disruption to the patient. Early detection by the MNA of elderly patients at risk of malnutrition allows for interventions prior to clinical deterioration . Risk for malnutrition or malnutrition identified by the MNA is also predictive of adverse outcomes and mortality .
The calculated GNRI is grouped into four grades, with a score of >98 as no risk and a score of <92 as high risk. Patients with nutritional risk at the time of admission when evaluated with the GNRI are more likely to develop complications and have longer lengths of stay .
The tool is easy enough for patients to screen themselves. One study showed that 96% of patients found the MUST assessment easy to understand and there was 90% agreement between the self-screening results and the results obtained by a trained health care professional .
Like the MNA and GNRI, higher scores on the NRS-2002 assessment correspond with worse clinical outcomes. For instance, patients with moderate or high nutritional risk on this screening were found to have a longer average length of stay than those without nutritional risk .
Impact of Nutrition on Outcomes
Once malnutrition is diagnosed in the elderly population, it is important to understand the effects of this state on outcomes, particularly surgical outcomes. In elderly people, malnutrition is an independent predictor of mortality in all settings – the community, nursing home, hosipital, or recently discharged from the hospital . A study of malnutrition and risk of complications was perfomed in patients presenting to University Hospital Zurich’s Department of Surgery for elective GI surgery. This group of 200 patients was screened for malnutrition preoperatively within 24 h of admission with three assessment tools (including NRS), then followed longitudinally, monitoring for complications. Complications were graded from 1 to 5, with grade 1 complications as the most minor and grade 5 resulting in death of the patient. This study found a correlation between nutritional risk and postoperative complications. In fact, every patient found to be at high risk of malnutrition as defined by the NRS developed a postoperative complication. The complication rate was 64% in patients at nutritional risk, while it was only 20% in patients without nutritional risk. Those patients at risk of malnutrition also had more severe complications, with 45% of patients at nutritional risk developing grade 3–5 complications compared to 7% of patients not at nutritional risk developing the same severity complications . Similarly, a prospective cohort study conducted in 26 hospital departments (including geriatrics) in 12 countries used the NRS-2002 to assess the relationship between nutritional risk and outcomes. In over 5,000 patients studied, patients determined to be at risk of malnutrition had more complications, higher mortality, and increased length of stay compared to patients identified as not at risk [6, 91].
Considering surgical patients, those with malnutrition have a higher likelihood of developing complications after major surgery [95, 96]. In particular, wound complications such as dehiscence and anastomotic leak, and infectious complications such as surgical site infections, are associated with poor nutrition . Malnutrition also influences overall functional status throughout the perioperative period. To demonstrate the impact of malnutrition on long-term functional status postoperatively, a German group followed 97 elderly patients at a large urban hospital with hip fractures. Patients had been evaluated with the MNA prior to hip fracture and were observed during their hospitalization and for 6 months after discharge. In the patients identified as malnourished or at risk for malnutrition, functional status was worse at all stages of care – prefracture, while inpatient, and at 6 months after discharge .
The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) prioritizes appropriate preoperative assessment of the geriatric surgical patient. In their guidelines released in conjunction with the American Geriatrics Society, the group recommends using a screening tool preoperatively to identify patients at severe nutritional risk (SNR) . This tool is comprised of three criteria: BMI <18.5 kg/m2, serum albumin <3.0 g/dL without renal or hepatic dysfunction, and unintentional weight loss >10–15% in the preceding year and is adapted from criteria set forth by ESPEN. Patients are considered at severe nutritional risk if any of the three criteria are met, and further nutritional assessment is recommended . When utilizing this tool preoperatively in geriatric patients, SNR is associated with poor postoperative outcomes. A study of elderly patients undergoing pancreaticoduodenectomy for benign disease at one institution were screened preoperatively for SNR. Those patients identified had a 5-year survival rate of 64.8% compared to 92.5% in patients of the age without SNR .
Energy Requirements in the Elderly
After the diagnosis of malnutrition or nutritional risk has been made in an elderly patient, the next concern that arises is how to address this state. Individualized nutrient balance can be estimated by directly determining nutrient intake compared to calculated energy expenditure/nutrient losses . Alternatively, protein and energy requirements can be estimated for this patient group. At baseline, the recommended energy intake for healthy adults is 25 kcal/kg/day and the recommended intake of protein in adults is 0.8 g/kg/day . This recommendation for protein nutrition was determined by the New Mexico Aging Process Study, a longitudinal study of nutrition in healthy elderly patients that was performed from 1979 to 2003 . Data from 1980 to 1990 of this study shows that women with protein intake greater than 0.8–1.2 g/kg of body weight had fewer health problems over the 10-year study period than women consuming <0.8 g/kg. Similarly, those patients who died or dropped out of the study due to illness had decreased energy intake . This information suggests that protein supplementation can improve outcomes.
Both energy and protein requirements are increased during periods of stress, such as hospitalization or surgical intervention. In order to prevent loss of lean muscle mass, protein intake must account for the increased breakdown in periods of stress and also in the setting of chronic medical conditions that result in protein loss, such as end-stage renal disease. Patients undergoing continuous renal replacement therapy (CCRT) are recommended 2.5 times the typical amount of protein . Similarly, in the severely ill elderly patient, the recommended requirement of protein is at least 1.0–1.2 g protein/kg/day and 20–30 kcal/kg/day of non-protein energy . During acute hospitalization, though, it is difficult to balance energy intake with basal energy expenditure (BEE). In acutely hospitalized elderly men and women (over age 80), the estimated energy expenditure in most patients is higher than energy intake. The resulting negative energy balance leads to a measurable decline in mid-arm muscle circumference during the hospital course . With elderly patients shown to be at risk of undernutrition during hospitalization, some studies even suggest a protein intake of 1.5 g/kg/day in elderly malnourished patients in an attempt to overcome protein losses and to replenish lean body mass [103, 105]. However, in a prospective cohort study, 21% of the included elderly patients were shown to have an average intake of less than 50% of their estimated maintenance energy requirements while hospitalized. These patients were found to have a higher rate of both in-hospital and 90-day mortality .
Perioperative Nutrition Management
Early initiation of nutritional intervention is extremely important in elderly patients because it is much more difficult to restore lost muscle mass. Body cell mass is restored at a much slower rate in the elderly as compared to younger patients . When determining etiology for this undernutrition, one common factor was frequent nil per os (NPO, nothing by mouth) orders and lack of utilization of oral supplementation, enteral, and parenteral nutrition . Surgery itself is a traumatic event with a significant risk of complications. Even without adverse outcomes, deconditioning and altered muscle mass related to immobility during hopsitalizaiton lead to reduced functional capacity extending for weeks beyond actual discharge. Elderly patients, with their reduced lean muscle mass, are particularly at risk of these consequences .
Sometimes, even when patients are identified as being malnourished or at risk of malnourishment, appropriate nutritional therapy is not initiated preoperatively. This phenomena is illustrated by a multicenter Belgian study in which 66% of the patients over 70 years were found to be malnourished but none of those patients had been referred to a dietician or started on supplementation . With evidence of missed opportunities for nutritional intervention, a new focus has been placed on improving nutrition in the perioperative period.
As illustrated in the study by Sullivan , hospitalization itself increases the risk of malnutrition, as patients are often placed on restrictive diets based on their chronic diseases (such as excluding sweets for diabetics or limiting calories for “heart healthy” diets), or made NPO for tests and interventions . One way to improve perioperative nutrition is to avoid prolonged preoperative fasting. Other than in the setting of emergency surgery or delayed gastric emptying, patients receiving clear liquids within 2–3 h of surgery are at no greater risk of aspiration than those who have been fasting for 12 h. In fact, patients who are loaded with carbohydrate supplementation the night before and 2 h before surgery had lower risk of postoperative insulin resistance and improved muscle mass . Similarly, there is no benefit to routine nasogastric tube decompression or delayed postoperative oral intake. Early oral and enteral nutrition does decrease infectious complications, hospital length of stay, and ICU length of stay .
Another simple intervention to encourage oral intake is to allow patients more freedom in their diet to choose foods that appeal to them (like salty foods and sweets) and opt for monitoring chronic conditions closely as opposed to strictly restricting intake of certain foods .
In addition to encouragement of ad lib oral intake, oral nutritional supplements (ONS) can also be utilized preoperatively. The question of the value of oral supplementation in improving nutrition and functional status has been evaluated with mixed results. One study showed that, while elderly patients in the community did have increased weight and decreased falls, functional status remained unaffected . In orthopedics in particular, interventions to optimize oral nutrition have been shown in multiple studies to result in improved outcomes. In a study of elderly patients with femoral neck fractures, once daily oral supplementation (250 ml, 20 g protein, 254 kcal) given for 30 days in the intervention group led to decreased mortality and complication rates both in-hospital and at 6 months after the fracture .
The results of the study of orthopedic patients contrast with the outcome of another study in which elderly patients with malnutrition were randomized and the intervention group given 8 weeks of supplementation starting at hospital discharge. For the follow-up period of 24 weeks, weight, BMI, anthropometrics, handgrip strength, quality of life, and need for health care professional or social services were documented. The patients receiving supplementation were shown to have a significant improvement nutrition status at 24 weeks compared to their baseline that was not seen in the control group; however the two groups were similar thereafter. Functional capacity as measured by handgrip strength improved in the supplemented group and was significantly improved over the control group until week 8, but then declined again . In this study, there was no clear-cut benefit seen for oral supplemental nutrition after discharge. This study leads to the question of whether or not discharge is too late to initiate nutritional interventions in a population and whether resouces should be focused on preventative interventions .
To better demonstrate the effects, Milne and colleagues performed a meta-analysis that included 62 trials and 10,187 randomized patients. They found that supplementation does result in small weight gain consistently in most studies. While there was no evidence to support that supplementation improved functional status or decreased mortality in all patients, it did show a beneficial effect on mortality for patients identified as undernourished. Additionally, this review found more evidence to support that supplementation reduces complications, though further investigation is needed in the future, as the studies were deemed to be poor quality . Despite the reported success of some individual studies, based on meta-analysis, outpatient counseling and oral nutritional supplementation of elderly malnourished patients in the community did not show consistent results .
In addition to oral supplementation of protein and energy, vitamin supplementation is also necessary in elderly patients. Vitamin D is commonly deficient in this age group and can lead to depression, cognitive changes, and increased fracture risk. Patients over 70 years should receive at least 800–1,000 IU of vitamin D daily. Hospitalized or institutionalized patients have an increased risk of developing vitamin D deficiency due to the lack of sun exposure. Vitamin B12 deficiency is also common and can be seen in patients with prior gastric surgeries or pernicious anemia as well as other neurologic or psychologic conditions. Normally, vitamin B12 and folate are obtained adequately by diet alone, but in some patients oral supplementation may be required. B12 can be supplemented orally at a dose of 1,000 mg/day, but deficiency does not tend to become apparent until after several years of decreased absorption [17, 100]. Calcium can also be depleted in geriatric patients. The recommended dietary intake in this patient population is 1,200 or 1,500 mg/dL to reduce the risk of osteoporosis and impaired functional capacity . Doubling of the daily multivitamin dose can be safely done while nutritional support is ongoing and until normal nutritional status is achieved .
Enteral nutrition (EN) is indicated regardless of risk of malnutrition, and is recommended to start immediately if the patient is not expected to eat for more than 7 days after surgery or if they cannot maintain more than 60% of the recommended oral intake for 10 days or more [108, 114, 115].
Preoperative (EN) has been shown to reduce postoperative complications in cancer patients receiving 3,500–4,000 cal/day (or 150% of calculated basal energy expenditure) when compared to oral diet alone . Both ESPEN and ASPEN guidelines emphasize the importance of preoperative nutritional optimization by recommending that operative interventions be postponed for enteral nutrition in pateints with elevated nutritional risk . ESPEN defines severe nutritional risk as weight loss of 10–15% within 6 months, BMI of less than 18.5 kg/m2, SGA grade C or albumin less than 3.0 g/L in the abscense of renal or hepatic dysfunction .
Supplementary EN in addition to oral nutrition has not been shown to be particularly beneficial outside of hip fracture patients and are poorly tolerated in the elderly . Patients receiving supplemental nocturnal tube feeds with hip fractures did show improved outcomes. Patients were divided into three groups based on anthropometric measurements. Patients from the “thin” and “very thin” groups were divided into a control and intervention group. Overnight supplementary enteral feeds were given via nasogastric tube (28 g protein,1,000 kcal) to the intervention group in addition to ad lib oral diet during the day. The group receiving supplmenetal feeds had improved anthropomentric measurements and plasma protein levels as well as shortened hospital length of stay and rehabilitation time .
There is also less evidence for the benefit of post-operative EN. Gastrointestinal cancer patients receiving preoperative and perioperative enteral feeds only had the same outcomes as patients whose feeds were continued through the postoperative period (though there was an improvement in both groups when compared to patients receiving no enteral nutrition). Oral supplementation has not been shown to improve clinical outcomes or functional capacity .
When comparing enteral and parenteral nutrition , EN is preferred unless contraindicated, as in intestinal obstruction, ileus, severe shock, or intestinal ischemia . In a review of 35 clinical trials performed by ESPEN, there is a significant benefit in EN when compared to PN in terms of length of hospital stay, infectious complications, and cost . Tube feeds should not, however, be initiated without careful consideration. For instance, tube feeds should not be given over oral nutriton for ease of care, as elderly pateints can typically maintain their nutritional needs with oral nutrition and assisted feeding or oral supplements. Additionally, the decision to start tube feeding in elderly patients requires reflection of the ethics surrounding this intervention, such as considering whether enteral will change outcomes or aid recovery or if the intervention is appropriate in maintaining the patient’s expressed wishes and goals of care .
In the elderly, enteral feedings via percutaneous endoscopic gastrostomy (PEG) are tolerated much better than feeds via nasogastric (NG) tube. Patients with neurological dysphagia were able to tolerate 93–100% of PEG feeds as opposed to only 55–70% of NG tube feeds . ESPEN does recommend placement of a jejunostomy feeding tube if the patient is already undergoing major abdominal surgery . Regardless of access type, longer-term supplementation beyond 4 weeks is recommended through definitive non-oral access. In terms of tube feed formula, feeds with immune-modulating substrates like argine are recommended for patients undergoing elective surgery for head and neck cancer and major abdominal surgery for cancer. Multiple meta-analyses have shown decreased postoperative complications rates and hospital length of stay in trauma and general surgical patients receiving immune-modulating tube feed formulas .
Age alone is not a contraindication to parenteral nutrition (PN). In the elderly population, routine postoperative PN is generally not recommended in general surgical patients as they had a 10% greater incidence of complications . A potential complicating factor of using PN in elderly patients is higher rates of insulin resistance leading to hyperglycemia and cardiac and renal dysfunction and may require that lipid content be increased. PN formulas should be adjusted to use higher lipid content . Although there is a higher risk of vascular erosion from central catheters in the elderly age group, parenteral nutrition is still recommended when oral or enteral nutrition is impossible or without sufficient nutrition for >7–10 days [103, 115]. In a review of 13 prospective randomized control trials, moderate to severely malnourished gastrointestinal cancer patients fed for 7–10 days with PN had a pooled reduction in postoperative complications compared to oral nutrition by 10%; however, only one of these studies of preoperative PN showed a statistically significant decrease in mortality .
In the geriatric population in particular, it is important to consider the ethical aspects of PN, treating it as an intervention and not routine care. Probability of recovery and goals of care should be weighted in the decision to initiate PN .
During the initiation of any nutrition regimen in an undernourished elderly patient, attention should be paid to the risk of refeeding syndrome. In this syndrome, phosphate can drop precipitously with introducing glucose rapidly electrolyte shifts also result in lower serum levels of potassium and magnesium. Thiamine levels can similarly drop. All of these changes occurring with rapid refeeding can invoke neurologic symptoms . In patients with delirium at baseline, these symptoms can be significant. It is important to note, however, that most cases of full-blown refeeding syndrome have been reported decades ago and occurred in the setting of severely malnourished patients receiving very high caloric loads (up to 75 kcal/kg/day). In modern practice, it is extremely rare to encounter the refeeding syndrome. Isolated refeeding hypophosphatemia is very common, but the clinical significance of this laboratory finding remains to be determined . Electrolyte levels, particularly potassium, magnesium, and phosphate, should be closely monitored (daily or more frequently as necessary) in the first few days of starting nutrition therapy and low levels should be aggressively treated with intravenous replacement. Withholding nutrition in the setting of mild hypokalemia, hypomagnesemia, and hypophosphatemia in the absence of clinical symptoms is not recommended.
Widening the scope of intervention beyond the immediate preoperative period, the concept of “prehabilitation” emerged from the desire to preemptively counteract the acute stress and negative effects of surgery by improving functional capacity preoperatively. Effective prehabilitation includes both nutrition and exercise inteventions and begins preoperatively, continuing through the perioperative period, and continues beyond the immediate postoperative period. One proposed prehabilitation process was tested in colorectal cancer patients prior to colon resection. Patients participating in moderate-intensity expercise and anxiety reduction strategies in addition to the “enhanced recovery after surgery” (ERAS) protocol were more likely to return to their preoperative baseline by 8 weeks after surgery (. Using this same model, the goal of nutritional interventions should be to optimize patients for the stress of surgery as opposed to reacting to and replacing protein loss. Patients at risk of malnutrition can be identified preoperatively using the various assessment tools previously described and interventions initiated . Tools like the MNA not only identify patients with malnutrition but also help target preoperative interventions by reviewing where points are lost in the assessment – simple interventions like supervision during eating for institutionalized patients with functional impairments can improve oral nutrition inake . Similarly, interventions that allow patients to make their own food choices can improve oral nutritional intake. One study changed the food service in a long-term care facility from preplated to cafeteria-like arrangement where patients were able to choose the type of food and amount they’d prefer to eat. This intervention resulted in increased energy intake among residents of the facility at risk of malnutrition .
Another example of prehabilitation is found in a multidisciplinary program utilized for elderly orthopedic patients with hip fractures. Patients received either standard nutrition or care from an integrated team that initiated nutritional support during the initial hospitalization and coordinated the transition of care to the outpatient setting for further maintenance. Using multiple measures of nutrition, there was a significant difference in energy intake between the two groups in the first week, with the intervention group taking in more daily energy and more mean protein. When nutrition was reassessed at 3 months, fewer patients in the intervention group were identified as malnourished or at risk of malnutrition .
Comprehensive Geriatric Assessment
The Comprehensive Geriatric Assessment (CGA) falls under the umbrella of prehabilitation. Identifying factors that contribute to poor outcomes in the elderly patient population can allow for preoperative interventions to be made. In the traditional model of preoperative assessment, focus is placed on individual systems or subjective assessments. Alternatively, the CGA provides a multidisciplinary approach that offers a complete evaluation of the elderly patient and cohesive plan of care for preoperative optimization that focuses on deficient areas . The original concept of the CGA comprised four major domains – physical health, functional status, psychological health, and socioenvironmental factors . These domains have been further expanded to include a number additional areas that include activities of daily living (ADL), instrumental activities of daily living (IADL), cognition, depression, fall risk, nutrition, polypharmacy, and social support. For purposes of the CGA, the MNA is typically used to evaluate nutrition . CGA has been utilized with success across a variety of clinical services. One study chose to focus specifically on elderly preoperative patients and the usefulness of CGA in prediciting outcomes. Patients with impairments in more than five of eight areas were found to be more likely to have an adverse outcome with an event rate of 37.8%. They were also more likely to die while in-hospital, have prolonged lengths of stay, or need to be institutionalized upon discharge .
The elderly population in the USA is expected to grow significantly over the next several decades. This group is especially at risk for malnutrition. The anorexia of aging and the physiological, psychological, and socioeconomic factors that contribute to a loss of lean muscle mass have already made undernutrition a prevalent condition in both the community and across all healthcare settings. Malnutrition is a predictor of poor clinical outcomes and contributes significantly to morbidity and mortality. Prompt recognition is therefore required in order to initiate timely interventions. Traditional serum testing, though straight forward, is not accurate in identifying malnourished patients or in monitoring the efficacy of interventions. Multimodal assessments that account for changes in functional capacity and severity of illness are more appropriate. It is now evident that reversal of malnutrition in the elderly is particularly difficult after significant lean body mass has been lost. Current treatment goals have shifted to emphasize the prevention of malnutrition as opposed to reaction to the state, promoting preoperative optimization and prompting initiation of enteral nutrition postoperatively. Looking forward, the future of managing geriatric patients in the surgical setting will continue to build on this foundation of prevention and include a multidisciplinary team and a holistic approach to overall care, including nutrition.
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