Malnutrition and nutrition intervention in the hospitalised patient Flashcards
LO
Malnutrition and Nutrition Intervention in the Hospitalised Patient (formerly nutritional assessment)
This aim of this guided online learning lecture is to understand the definition, diagnosis and impact of malnutrition. It will also explore indications and types of artificial nutrition support used in the hospitalized patient.
This session relates to the following TILO:
- Appetite regulation: Outline the hypothalmic circuits controlling body weight and relate these to the aetiology, complications and management of obesity and malnutrition
Session plan
Defining Malnutrition
Malnutrition due to starvation, disease or ageing can be defined as a state resulting from lack of uptake or intake of nutrition, leading to altered body composition and body cell mass, leading to diminished physical and mental function and impaired clinical outcome from disease.
In 2014, the British Association of Parenteral and Enteral Nutrition, known as BAPEN, published a report based on the findings of data from hospitals in the UK that participated in four nutritional screening week surveys. Between 2007 and 2011. Figure 1 shows the report’s findings relating to the prevalence of malnutrition by age group identifying a curvilinear relationship where the highest prevalence of malnutrition occurred in the youngest and oldest adult age groups.
Malnutrition is more common in women than men, especially in the older age groups. Whilst malnutrition was found to be widely distributed across all hospital boards, figure 2 shows that the highest prevalence was found within oncology and care of the elderly.
When considering diagnostic criteria, malnutrition was most prevalent in those with gastrointestinal disease compared to musculoskeletal, cardiovascular or respiratory diseases. To generalise, those at risk of malnutrition are older people over the age of 65, particularly if they’ve been admitted to hospital. People with long term conditions such as diabetes, kidney disease, chronic lung disease, people with chronic progressive conditions such as dementia or cancer. People who abuse drugs or alcohol. And patients with any kind of gastrointestinal dysfunction.
The 2014 BAPEN report identified that every one in three person admitted to hospital were malnourished at point of admission, suggesting that much of malnutrition originates in the community. However, we know from Pennington and McWhirter’s landmark study published 20 years earlier and referenced on the last slide of this presentation, that malnutrition is often unrecognised and undiagnosed in the acute setting. The study identified 30% of 500 patients admitted to hospital for treatment had moderate to severe malnutrition on admission. Of the patients who stayed in hospital for more than one week, 65% continued to lose weight, with only a few of the malnourished patients being referred for nutritional intervention. Today, 70% of people will have lost weight, critically the majority of this weight being fat free mass, by the time they have left hospital. The greatest weight loss is seen in those who were initially the most undernourished at admission.
What then are the factors that exacerbate malnutrition or put a patient at risk of malnutrition during their hospital stay?
Figure 3 highlights that this is a multifactorial problem. Disease related anorexia describes a loss of appetite as a result of pathophysiological mechanisms and modification of central regulation of feeding behaviour, which is observed in the presence of disease. The metabolic response to stress involves muscle breakdown, to amino acids for gluconeogenesis and protein synthesis for the immune response and tissue repair. There is an increased demand for energy, proteins and micronutrients. This results and loss of body mass, most notably body protein.
The paradox of the metabolic response to injury is that it is essential to provide the substrates necessary for survival. But in extreme cases it can result in such dysfunction and tissue loss that survival is threatened. Patients with prior malnutrition who then develop acute illness have less reserve with which to face that illness. As an example, it is theorised that reserves of a 74 kilogram man equate to a total of just under 192,000 kilocalories. Although most hospitals in high income countries provide food that can meet patients nutritional requirements, more than 40% of this food might be left on the plate, resulting in the consumption of less than 80% of the recommended protein and calorie intake by patients capable of eating. The reasons for reduced food intake, especially in older adults, are multifactorial and can stem from the belief of patients that poor appetite is to be expected during hospitalisation, with many supposing that their appetite will return to normal after discharge. Other reasons include gastrointestinal symptoms, inactivity, depression or low mood, inflexibility of hospital systems, quality of the food, lack of motivation and the belief by both staff and patients that medical treatment is the main priority and that food is of secondary importance.
The Impact of Malnutrition
The adverse effects of malnutrition on clinical outcomes was documented over 80 years ago, when Hirum Studley showed that in patients undergoing surgery for perforated duodenal ulcer, post-operative mortality was 10 times greater in those who had lost more than 20% of their body weight preoperatively, compared with those who had lost less.
Patients who are unable to mobilise adequate amounts of endogenous nitrogen in response to stress, experienced greater morbidity and mortality than those who are able to generate a catabolic response from adequate stores of muscle tissue. Eighty years on from Hiram Studley’s work, the Office of National Statistics, reveals that people in England and Wales are still dying in hospital, the primary or associated cause being malnutrition.
Malnutrition causes physical and functional decline and has poorer clinical outcomes. This study by Lim et al, published in 2012, is an example of one of the many studies that show a clear relationship between malnutrition and clinical outcome in the 21st century. Their cohort study, published in 2012 involves the assessment of nutritional status of 818 adults on hospital admission. Hospitalisation outcomes over three years were adjusted for gender, age, ethnicity and matched for diagnosis related group. Malnourished patients had longer hospital stays and were more likely to be readmitted within 15 days compared to well nourished patients. Mortality was higher in malnourished patients at one, two and three years. As shown in figure 5 overall, malnutrition was a significant predictor of mortality.
Along with the physical and functional decline and poorer clinical outcomes, the cost of malnutrition is significant. In November 2015, a report was published estimating the cost of malnutrition in both adults and children in England.
Your first question then, what is the cost of malnutrition in England per year? £19.6 billion, £550 million or £24.7 million?
Malnutrition is estimated to cost £19.6 billion in England, which is about 15% of the total expenditure on health and social care. Most of the costs of malnutrition are in secondary health care. The health and social care costs are estimated to be three times greater for malnourished patients than a well nourished patient. Costs are likely to rise in the future as the population ages. Economic analysis shows that identifying and treating malnutrition with nutrition support can save at least 65 million for England.
Diagnosing Malnutrition
Screen
- A simple tool to identify risk.
- Carried out by any HCP.
- This is not assessment or diagnosis.
Assess - Dietitian
- A systematic process of collecting & interpreting information to determine the nature and cause of the nutrient imbalance.
- note: anthropometry= the scientific study of the measurements and proportions of the human body.
Diagnose
- Nutrition diagnosis
Then PIME
- Plan
- Implement
- Monitor
- Evaluate
So how then do we identify and diagnose malnutrition in the acute setting?
The validated malnutrition universal screening tool (MUST) is the most commonly used in the UK to screen for adults malnutrition in both the community and hospital settings. It is a rapid and simple method of screening based on BMI, unplanned weight loss and presence of acute disease. It categorises individuals as being at low, medium and high risk of malnutrition and provides immediate management guidelines based on the risk category.
Malnutrition screening is required within six hours of hospital admission and weekly thereafter. This screening tool does have limitations and can miss malnourished clinical populations, in particular, where over hydration, such as ascites and oedema, is common or where specific screening for functional impairment is desired. If a patient triggers as a result of the screening process, they are referred to a dietician for the assessment of nutritional and functional status.
Nutrition assessment is a comprehensive evaluation carried out by a registered dietitian for defining nutrition status, using anthropometric measurements, biochemical data, medical, social and nutritional histories and physical examination. Nutrition assessment involves interpretation of data from the nutrition screen and incorporates additional information. The purpose of assessment is to gather adequate information in which to make a professional judgement about nutritional status.
Assessment begins with anthropometry, the measurement of the physical properties of the body. The body is composed of several compartments which are targeted and affected differently by starvation, chronic disease or acute disease or injury related malnutrition and therefore, different anthropometric tools are used by the dietician to measure particular compartments. The scales shown in Image one represent that recent unplanned changes in weight reflect acute changes in protein energy status and have been associated with increased length of stay morbidity and mortality. At an individual level, BMI has several limitations due to the influence of factors such as gender, ethnicity and age being ignored. BMI also cannot distinguish between fat mass and fat free mass, therefore BMI plays minimal significance in the dietetic assessment unless it is very low. The next two images showing measurement of mid upper arm circumference and tricep skin fold thickness are quick and easy measures that can be achieved at the bedside. They can be used to calculate mid arm muscle circumference and assessment of lean body mass. This is an important clinical outcome measure as improved lean body mass is associated with reduced length of hospital stay and improved functional ability. Other anthropometric measures of body composition include the use of multi frequency bioelectrical impedance analysis, which are used in such patient populations as the renal and haematology patients.
CTs can provide important quantitative information on muscle composition and distribution and can measure fat and muscle content from one abdominal cross-sectional slice. Images from CT scans distinguish between visceral and subcutaneous fat and are considered highly accurate in evaluating levels of fat and fat free mass. However, they are expensive and expose individuals to a small amount of radiation. Therefore, their use in detailing body composition tends to be restricted to research. However, they are now being more frequently used within specialities where CTs are already part of the clinical treatment pathway. The paper referenced here, published by dietician Doctor Oonagh Griffin in 2019, is a good example of the use of diagnostic restaging CT scans to measure body composition. Here it determined the prevalence of sarcopenia in patients with borderline resectable pancreatic cancer. Low muscle attenuation at diagnosis, coupled with lean tissue loss during chemotherapy, independently increased mortality risk.
The final image represents hand grip strength, reflecting upper extremity muscle strength, which responds earlier to nutritional deprivation and nutritional repletion than other parameters such as muscle mass or body mass. Muscle strength can predict mortality and morbidity independent of muscle mass. A reduction in mortality risk for every one kilogram increase in handgrip strength has been reported. This measure is quick and easy to perform at the patient bedside.
Biochemistry forms part of nutritional assessment. Tests used to estimate nutrient availability in fluid and tissue is critical for assessment in clinical nutrient deficiencies. Measurements of micronutrient and trace elements concentrations are time consuming and expensive, and therefore there needs to be a justified clinical need for requesting these. Many of these results are skewed as a result of the acute inflammatory response and therefore are not measured until CRP is below 10 micrograms per litre. Where parenteral nutrition is used, biochemistry requires intensive monitoring.
Medical histories can also prove useful, providing insight into nutrient related problems, alcohol and drug use, increased metabolic needs, increased nutritional losses. Chronic disease, recent major surgery or illness or surgery of the GI tract. Nutrition history can reveal anorexia, loss or sense of taste or smell, excessive alcohol intake, poor fitting dentures, fad dieting, chewing or swallowing problems. A diet history is perhaps the best means of obtaining dietary intake information and refers to a review of the individual’s usual patterns of food intake and the food selection variables that dictate the food intake. Social aspects of the medical history may also relate to nutrition status. For example, information pertaining to socioeconomic status, the individual’s ability to purchase food independently, whether the person is living or eating alone, and physical or mental disabilities. Smoking or drug or alcohol addiction also.
Indirect calorimetry is the most reliable method to measure energy expenditure and guide energy prescription. The most widely used form of indirect calorimetry is the measurement of resting metabolic rate using a respirator gas exchange canopy as shown in the picture. However, indirect calorimetry carries inherit limitations, greatly restricting its use in real live clinical practice. Therefore, predictive equations estimating resting metabolic rate are used in clinical practice to determine an estimated energy requirement, that is the average dietary energy intake that is predicted to maintain energy balance in an adult of a defined age, gender, weight, height and level of physical activity. There are a number of predictive equations, the dietician will have critically appraised the equations in relation to their own specialism.
It should be noted that there are significant limitations to the use of these equations, and in most clinical settings, the majority of predictive equations have low to moderate performance, with the best generally reaching an accuracy of no more than 70%. They will tend to be used as a starting point only to determine a baseline set of requirements. The assessment of status determines the nutritional diagnosis, outcomes, and intermediate goals.
Indications for Nutrition Support
Q. What is artificial nutrition support?
Nutrition support should be considered in people who are either:
- Malnourished =
- BMI < 18.5 kg/m2 or
- Unintentional weight loss >10 % past 3 - 6 / 12 or
- BMI < 20 kg/m2 + unintentional weight loss > 5 % past 3 – 6 / 12.
- At risk of malnutrition =
- Have eaten little or nothing for > 5 days and / or are likely to eat little or nothing for the next 5 days or longer or
- Have a poor absorptive capacity, and / or have high nutrient losses and/or have increased nutritional needs from causes such as catabolism.
How then do you as a clinician determine whether nutrition support is indicated, for example when you’re clerking a patient or reviewing the patient as part of ward round?
The National Institute for Health and Care Excellence (NICE) state that nutrition support should be considered in people who are either malnourished, defined as having a BMI below 18.5, or unintentional weight loss of greater than 10% in the past three to six months, or a BMI below 20 with unintentional weight loss of greater than 5% within the same period. Or those at risk of malnutrition who have eaten little or nothing for greater than five days, or are likely to eat little or nothing for the next five days or longer, or have a poor absorptive capacity or high nutrient losses or increased nutritional needs from causes such as catabolism.
What is artificial nutrition support?
Artificial nutrition support can be defined as the provision of enteral or parenteral nutrients to treat or prevent malnutrition.
Algorithm for the Treatment of Malnutrition
The decision to start artificial nutrition support requires consideration of the following algorithm developed by Stratton and Elia.
In the first instance, if the oral route is safe and possible, this would always be the preferred approach. In cases where the oral route is not possible, a decision needs to be made as to whether the GI tract is functional and accessible, if so, enteral feeding needs to be considered. If the GI tract is not functional or accessible, parenteral nutrition is then considered.
Taking a moment to look at the algorithm, you will note there is a need for continued monitoring and evaluation of the current nutrition route and to either change or increase the number of feeding routes if nutritional intake remains suboptimal or long term feeding options are required.
The decision to start or withdraw artificial nutrition’s support is intertwined with ethical and legal considerations. The paper referenced here by Druml et al represents the European Society of Parenteral and Enteral Nutrition (ESBEN) guidelines on the ethical aspects of artificial nutrition and hydration.
Artificial Nutrition Support: Enteral
Route:
- Enteral nutrition (EN) is superior to parenteral nutrition (PN).
- Where parenteral nutrition is used, the aim is to return to enteral → oral feeding as soon as (where) clinically possible.
If artificial nutrition support is indicated, enteral nutrition is superior to parenteral nutrition as it uses the gut. Where parental nutrition is used, the aim is to return to enteral of oral feeding as soon as clinically possible.
The first line approach to enteral feeding is the use of a feeding tube via the nose and into the stomach, known as an NG Tube, a nasogastric tube. However, sometimes this is contraindicated as shown in the image here, showing gastric outlet obstruction and therefore a feeding tube needs to be placed distal to the stomach, either in the duodenum or in the jejunum.
Where longer term enteral tube feeding needs to be considered a gastrostomy or jejunostomy tube can be inserted. The dietician will determine the type of nutritional feed to put down the feeding tube, this is dependent on a number of factors.
Artificial Nutrition Support: Enteral
What are the complications associated with enteral feeding?
Misplaced nasogastric tubes accounted for 21 deaths and 79 cases of harm in a six year period, as reported by the National Patient Safety Agency. An example of which is shown in the image. When an NG tube has been placed, an aspirate needs to be obtained from the tube, indicating a pH of 5.5 or less, which reflects the gastric contents, the acidity in the stomach, which is not found anywhere else in the GI tract. If there is a pH greater than 5.5, a chest x ray is indicated. The other complications related to enteral feeding are listed here. You may wish to visit the ESPEN web site to determine disease specific enteral feeding guidelines.
Artificial Nutrition Support: Parenteral
Parenteral nutrition (PN): The delivery of nutrients, electrolytes and fluid directly into venous blood.
Indications:
•An inadequate or unsafe oral and/or enteral nutritional intake
OR
•A non-functioning, inaccessible or perforated gastrointestinal tract
Composition:
- Ready made / bespoke “scratch” bags.
- MDT → fluid and electrolyte targets
The dietician will compose the parenteral nutrition bag, they will use either a ready made bag or prescribe a “scratch” bag. The dietician will liaise with the multidisciplinary team to determine the fluid and electrolyte targets for that day.
Artificial Nutrition Support: Parenteral
Access
Access:
- Central venous catheter (CVC): tip at superior vena cava and right atrium.
- Different CVCs for short / long term use.
Central venous catheters tend to be used, either inserted in the subclavian, jugular or femoral veins with tip at the superior vena cava, or peripherally inserted central catheters with a tip still at the superior vena cava, but the catheter being inserted from the antecubital fossa and advanced into the central vein, which can be done at the bedside.
Different CVCs are used for short and long term use of parenteral nutrition, and they are better described in the paper documented here by Pittiruti, which reflects the ESBEN guidelines on parenteral nutrition CVCs.
Q. What are the complications associated with parenteral nutrition?
There are mechanical, metabolic and catheter related infectious complications associated with parenteral nutrition.
Mechanical complications tend to be around when the line is inserted for use for parenteral nutrition as shown in the image.
Metabolic complications tend to occur once we start feeding the patient. Intravascular catheters are one of the main causes of bacteraemia and septicaemia in hospitalised patients.
National Confidential Enquiry into Patient Outcome and Death Report published in 2010, highlighted a lack of adequate consideration of enteral nutrition, delays in the initiation of parenteral nutrition, and inadequate assessment and monitoring resulting in avoidable metabolic an infective complications. One of the recommendations from the report was that patient assessment should be robust, ideally utilising the skills of a nutrition support multidisciplinary team
Does Nutrition Support Benefit the Malnourished Patient?
An updated systematic review and meta-analysis included trials comparing oral and enteral nutrition support interventions, with usual care in non critically ill medical patients who were malnourished. The primary outcome was mortality. A total of 27 trials were included, of which five were published between 2015 and 2019. As shown in figure 6, patients receiving nutrition support compared with patients in the control group had significantly lower levels of mortality.
A sensitivity analysis suggested a more pronounced reduction in the risk of mortality in recent trials, 2015 or later, compared with that in older studies, in patients with established malnutrition compared with that in patients at nutritional risk, and in trials with high protocol adherence compared with that in trials with a low protocol adherence. Nutritional support was also associated with a reduction in nonelective hospital readmissions, higher energy and protein intake, and weight increase. The review included a large trial known as the EFFORT trial- the Effect of early nutritional support on Frailty, Functional Outcomes and Recovery of malnourished medical inpatients Trial. The study, published in The Lancet, is regarded as a well-designed, unblinded multicentre trial, aiming to test the hypothesis that providing patients at nutritional risk with individualised nutrition support would result in a better outcome than in those given the standard hospital diet without any further nutritional intervention.
The investigators were able to show that in this intervention, it led to a significantly better outcome, including all-cause mortality, intensive care unit admission, non-elective hospital readmissions, major complications, and functional status at day 30.
Albumin
The acute phase response.
- Albumin synthesised in the liver.
- Low plasma albumin = poor prognosis.
- A negative acute phase protein = ↓ plasma albumin when ↑ inflammation.
The acute phase response.
- Inflammatory stimulus → activation of monocytes & macrophages → release cytokines.
- Cytokines act on liver to stimulate production of some proteins whilst downregulating production of others e.g. albumin.
Albumin is the most abundant circulating protein in the plasma of healthy individuals. About 10 to 15 grams of albumin is produced in the liver by hepatocytes every day. There is clear evidence to show that low albumin levels in the unwell patient predicts poor prognosis. Albumin synthesis is stimulated by hormones such as insulin, cortisol and growth hormone, whilst it is inhibited by proinflammatory substances, including interleukin 6 and tumour necrosis factor.
In the acute inflammatory state, cytokines will act on the liver to stimulate production of some proteins whilst down regulating production of others, including albumin. Furthermore, degradation and transcapillary losses of albumin increase in this state.
Albumin
- A moderate inflammatory stimulus will induce plasma acute phase protein changes.
- The negative acute phase protein, albumin, will↓.
As described by Gabay and Kushner, as part of the acute phase response, we see reduced synthesis of albumin.
Is albumin a valid marker of malnutrition in the acute hospital setting?
No. Albumin synthesis reduces in response to inflammation, therefore it is not a valid marker of nutritional status, nor is it an indication to start nutrition support. The best evidence of this is hypoalbumin aemia seen in obese trauma patients.
The dietician will be focused on the cause and impact of the inflammatory state on nutrition status rather than albumin levels.
Refeeding Syndrome (RFS)
Consequences of RFS:
A group of biochemical shifts & clinical symptoms that can occur in the malnourished or starved individual on the reintroduction of oral, enteral or parenteral nutrition.
Refeeding syndrome is not a singular condition, but a group of biochemical shifts and clinical symptoms that can occur in the malnourished or starved individual upon their reintroduction of oral, enteral or parenteral nutrition. During starvation, the body aims to utilise energy stores, and there is a reduction in insulin secretion and an increase in glucagon secretion to produce glucose. Glycogen stores in the liver and amino acids in skeletal muscle are metabolised into glucose. Once these stores are depleted, which can be within 24 to 72 hours, metabolism shifts to derive energy from ketone production due to free fatty acids being released from fat stores, which are used instead of amino acids. This shift spares skeletal muscle breakdown and fat free mass is preserved to an extent.
In addition, there is a decrease in basal metabolic rate and the brain adapts to using ketone bodies instead of glucose, resulting in a loss of fat mass.
In an effort to reduce energy expenditure, the action of cellular pumps is reduced, with electrolytes able to leak across the cell membrane. During starvation, there is an increase in extracellular water, total body water and sodium, and a depletion of total body potassium, magnesium and phosphate. Serum concentrations of these electrolytes are maintained whilst intracellular stores are depleted, sodium and fluid also leak into the cells, resulting in sodium and fluid intolerance. Micronutrient stores become depleted and thiamine deficiency is likely as it is water soluble and the body has limited stores.
The introduction of carbohydrate results in the secretion of insulin, stimulating the sodium-potassium ATPase pump, requiring magnesium as a co factor. This drives potassium into cells and sodium and fluid out of cells into the extracellular space. The carbohydrate and insulin secretion drives phosphate into cells as it’s required for energy storage as ATP. This results in an increased cellular uptake of glucose, potassium, magnesium and phosphate, and a subsequent reduction in extracellular concentrations. Thiamine is a coenzyme in carbohydrate metabolism and deficiency can occur on refeeding in a vitamin B depleted patient. These low concentrations of electrolytes and thiamine can then result in the clinical manifestations. In addition, carbohydrate reduces sodium and fluid excretion, causing an expansion of the extracellular fluid compartment, resulting in refeeding oedema and fluid overload.
In patients at risk of refeeding syndrome overrapid and unbalanced provision of oral, enteral and parenteral nutrition can result in shifts in fluid and electrolytes. These biochemical abnormalities can result in a spectrum of presentations and ultimately death.
Consequences of RFS:
- Arrhythmia, tachycardia, CHF → Cardiac arrest, sudden death
- Respiratory depression
- Encephalopathy, coma, seizures, rhabdomyolysis,
- Wernicke’s encephalopy
Q. According to the National Institute for Health and Care Excellence (NICE), what are the criteria for defining the risk of RFS?
NICE define the criteria for refeeding syndrome risk as follows.
Refeeding Syndrome (RFS) - Management
We manage patients at risk of refeeding syndrome as follows. The dietician will give no more than 10 to 20 kcal per kilogram of nutrition, of that, 40 to 50% of the energy will be from carbohydrate.
Micronutrients will be given from the onset of feeding. Electrolytes need to be checked and replaced daily following trust policy, and Thiamine needs to be administered, the first dose of which needs to be given 30 minutes before onset of initial feeding.
Fluid balance needs to be monitored to check for fluid shifts and to minimise the risk of fluid and sodium overload.
Session review
