Malnutrition Flashcards
define malnutrition
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
describe the prevalence of malnutrition by age, sex and hospital ward
more common in women than men especially in older age groups
most common in oldest and youngest age groups (18-19 and 90+)
most common in care of elderly and oncology
more common in those with gastrointestinal disease compared to cardio, resp and msk
generally - people over 65 especially if they have been admitted to hospital, people with chronic conditions (diabetes, lung disease, kidney disease) + chronic progressive diseases (cancer, dementia), people who abuse drugs or alcohol, people with any GI dysfunction
compared malnutrition in community vs in hospital
1 in 3 admitted to hospital were malnourished on admission → suggests that majority originates in community
but malnutrition is unrecognised and undiagnosed in the acute setting → 70% of patients lost weight (mainly muscle mass) at discharge and the most vulnerable are those who came in malnourished
what makes people in hospital particularly vulnerable to malnutrition
disease related anorexia - loss of appetite due to pathophysiological mechanisms + disruption of central regulation feeding behaviour
patients consume less than 80% of food on plate in hospital
belief that it is normal for appetite to decrease in hospital → held especially by older patients
belief by patient + staff that medical treatment is more important than food
what is the paradox of the body response to injury
metabolic response to breakdown particularly proteins into substrates necessary for survival e.g. for immune system + tissue repair
but this metabolic response can then threaten survival in extreme cases e.g. due malnutrition + loss of muscle mass it causes
how is malnutrition related to being acutely unwell
disease related anorexia - loss of appetite due to pathophysiological mechanisms + disruption of central regulation feeding behaviour
body’s response to stress → muscle breakdown into AA for gluconeogenesis + protein synthesis to supply immune response and tissue repair
increased demand for energy, protein + micronutrients → largest demand is for protein
patients who already are malnourished then become acutely unwell as they have less kilocalorie reserve to face illness
how does malnutrition affect clinical outcomes
causes physical and functional decline + worsens clinical outcomes
post operative mortality is 10x greater in people who have lost over 20% of bodyweight preoperatively
inadequate muscle tissue → unable to mobilise adequate amounts of endogenous nitrogen in response to stress → greater morbidity compared to those who have sufficient muscle tissue
people in england + wales still dying in hospital from malnutrition as the primary cause
how much does malnutrition cost the NHS
£19.6 billion per year
costs for malnourished patient x3 than well nourished
majority of cost is in secondary care
costs will rise in future as population ages
how is malnutrition diagnosed
screening → assess by dietician → diagnose
screen using MUST - used in community + hospital, based on BMI, unplanned weight loss + acute disease, categorises in low, medium + high risk of malnutrition
has to be done within 6 hours of hospital admission and every week thereafter
can miss malnourished clinical populations → especially where overhydration is common e.g. ascites
ASSESS:
dietician - defines nutrition status
anthropometry - physical measurements of body compartments e.g height, weight, mid arm muscle circumference
biochemistry → used to estimate nutrient availability in tissue and fluid to assess for deficiencies
testing for trace elements + micronutrients is expensive → needs justification
results can be skewed due to inflammatory response so not measure until CRP is below 10, results are monitored intensely in parenteral nutrition
history → drug + alcohol, diet, metabolic needs, nutritional loss, chronic disease, major surgery or illness, GI tract surgery, medication
nutrition history - anorexia, loss of taste or smell, excessive alcohol, poor fitting dentures, chewing or swallowing problems, fad diets, allergy, dietary restriction
dietary history - food intake
social history - socioeconomic status, living alone,
indirect calorimetry - most reliable measure of energy expenditure + guide energy prescription → measures resting metabolic rate using respirator gas exchange canopy (not used in clinical practice) so equations are used in clinical practice to determine estimated energy requirement
DIAGNOSE:
based on the dietitian assessment of nutritional status
create plan → implement it → monitor → evaluate
what are the limitations of BMI
what are the impacts of these
impact of gender, age ,e thnicity is ignored
cannot distinguish between fat mass and fat free mass
has minimal significance is dietetic assessment unless it is very low
what does recent unexplained weight loss specifically suggest in regards to body reserves
muscle loss and therefore protein loss
what are the anthropometric measurements carried out by dietician during malnutrition diagnosis
what do they indicate
anthropometry - measures body different compartments as they are affected differently by malnutrition
weight - recent unplanned weight loss reflects changes in energy protein status → impacts morbidity and mortality
BMI - has low significance due to its limitations unless very low
mid upper arm circumference and tricep skin fold thickness → used to calculate mid arm muscle circumference → used to assess lean body mass → associated with length of hospital stay and functional ability
multi-frequency bioelectrical impedance analysis - used in renal and haematology patients
CT - muscle distribution + composition, differentiate between visceral + subcutaneous fat, assess levels of fat and fat free mass very accurately (but expensive + radiation exposure so assess body composition mainly in research or when CT is part of clinical treatment pathway already)
hand grip strength → reflects upper extremity muscle strength → responds earlier to nutritional deprivation and repletion than other measurements e.g. muscle or body mass → the muscle strength can predict mortality and morbidity independent of muscle mass (reduced mortality for every 1kg increase in hand grip strength)
define estimated energy requirement
how is it determined
how is it used
average dietary energy intake predicted to maintain energy balance in an adult of defined age, gender, weight, height and level of physical activity
related to resting metabolic rate (but this is energy expended at rest)
using predictive equations - but have limited use in practice and have maximum accuracy of 70%
used as starting point to determine baseline set of energy requirements that patient has
what are the criteria for nutritional support
what is artificial nutrition support
provision of enteral or parenteral nutrients to treat or prevent malnutrition
what are the considerations when starting/stopping artificial support
feeding route:
oral is best → then enteral → parenteral
always need continued monitoring + evaluation of nutrition route
change or reconsider number of feeding routes if nutritional intake is sub optimal or long term feeding is required
starting and stopping requires ethical and legal considerations
what is enteral artificial feeding
how is it done
delivering directly nutrition to stomach or small intestine
naso-gastric tube is first line = NG tube
if naso-gsastric tube is contraindicated e.g. if gastric outlet is obstructed → so tube needs to be distal to stomach
then naso-duodenal (NDT) or jejunal tube (NJT) is used
long term >3 months = gastrostomy or jejunostomy (tube inserted into stomach or jejunum through abdomen)
nutritional feeds that can be used - renal, low sodium, respiratory, immune, elemental, peptide
how do the feeding routes for artificial nutrition compare to each other
oral is the best
enteral is superior to parenteral
when parenteral feeding is used, the aim is to move to enteral and then oral feeding as soon as clinically possible
what are the complications of enteral nutrition
mechanical - misplacement of tube, blockage of tube, buried bumper - part of gastronomy tube becomes lodged in gastric wall
metabolic - hyperglycaemia, deranged electrolytes
GI - aspiration, nasopharyngeal pain, laryngeal ulceration, vomiting, diarrhoea
what do you have to do to make sure NGT is in correct place
aspirate the contents
if the pH is <5.5 that indicates it is in the stomach as this pH is not found anywhere else in the body
if pH >5.5 then a chest x ray needs to be done and interpreted by professional
where is parenteral nutrition inserted
using central venous catheter
centrally inserted into jugular, subclavian or femoral veins to reach the tip of of superior vena cava
or can be peripherally inserted via antecubital fossa to reach tip of superior vena cava
different central venous catheters are used depending on length of nutrition
what predictive effect does albumin have
why
low plasma albumin = marker of poor prognosis
albumin production is inhibited by pro-inflammatory cytokines e.g. IL-6, TNF → therefore is a negative acute phase protein → levels decrease as inflammation increases
also in the acute inflammatory state there is increased degradation and transcapillary losses of albumin
what effect does carbohydrate introduction have on the body during starvation
insulin secretion → stimulates action of Na+K+ ATPase pump which requires Mg2+ as a co-factor → drives K+ into cells and Na+ out
carbohydrate + insulin drive phosphate into cells as it is need to make ATP
there is increased cellular uptake of glucose, K+, Mg2+ and phosphate → therefore a decrease in the extracellular concs of glucose, K+ Mg2+ and phosphate
thiamine is co enzyme needed for carbohydrate metabolism → therefore deficiency of thiamine can occur on refeeding in a vitamin B depleted patient
carbohydrate also reduces Na+ and fluid excretion → expansion of extracellular fluid compartment → refeeding oedema and fluid overload
therefore refeeding syndrome
who is at risk of refeeding syndrome
what impact do drugs given on ICU have on nutrition
why do the effects of small bowel resection vary between patients
depends on the type, length and quality of small bowel left and whether or not they still have colon
most absorption happens in jejunum, apart from vitamin B12 and bile salts which are absorbed in the ileum
presence of colon is important because it can absorb , water, Na+ and fatty acids and slows intestinal transit → further aids absorption
when colon + ileum is not present e.g. in jejunostomy → large amounts of fluid and electrolytes are lost and small bowel transit is very fast
the length of jejunum left determines whether nutrition can be supported by diet alone:
<100 cm of jejunum left = long term IV fluid and electrolytes
<75cm jejunum = long term parenteral nutrition, fluid + electrolytes
<50cm jejunum + colon = long term parenteral nutrition, fluid + electrolytes
how do the losses between jejunostomy and jejunocolic anastomosis compare
jejunocolic lose much less fluid and electrolytes as they are able to resorb much more as colon is present and it slows down small intestinal transit to all further reabsorption in jejunum
there are significant intestinal losses in jejunostomy and small bowel transit is very fast
how is high stomal loss managed
fluid restriction → hypotonic solutions e.g. water, alcohol, tea, coffee will cause net influx of Na+ from plasma into gut lumen due to the large concentration gradient between the lumen and the blood, water will follow Na+ → therefore a high stoma output
also should reduce hypertonic fluids which contain sorbitol e.g. juice, coca cola and this high concentration induces secretions from enterocytes in order to dilute them
give oral rehydration solution:
Na+ concentration = 90mmol/l
glucose concentration = 111mmol/l
No K+
SGLT1 transport will co transport glucose and Na+ across apical membrane
Na+ then actively pumped across basolateral membrane into blood via Na/K+ ATPAse
H2O follows Na+
large amounts of Na+ and H2O reabsorbed → much lower stomal losses → prevents dehydration
