Presentation on theme: "Nutrition Dr James F Peerless July 2013. Objectives Introduction to nutrition Assessment of the patient Feeding requirements – Macro- & micronutrients."— Presentation transcript:
Nutrition Dr James F Peerless July 2013
Objectives Introduction to nutrition Assessment of the patient Feeding requirements – Macro- & micronutrients Enteral vs. parenteral feeding Refeeding syndrome
Introduction Nutrition support: – enteral or parenteral provision of calories protein electrolytes vitamins, minerals trace elements fluids Goal of therapy is to supply each substrate in the right quantity necessary to meet the metabolic needs of each patient Total energy Protein Lipids (fat) Carbohydrates Micronutrients
Nutrition Aims of nutritional support on the ICU: – Provide exogenous substrates to meet macro and micronutrient requirements in dependent patients – Help protect vital visceral organs and attenuate breakdown of skeletal muscle – Reduce net protein catabolism Contraindications to commencing feed (enteral or parenteral) on ICU: – Able to resume full oral diet within 3 days – Inappropriate for ethical reasons
Assessment of nutritional status It is estimated that 60% of patients are malnourished prior to hospital admission Malnutrition is associated with a poor outcome – increased LoS and incidence of complications in critical care. Assessment difficult – Anthropometric measurements good for populations – BMI does not reflect acute changes – Biochemical tests have limitations
Subjective Global Assessment History Weight change (chronic and acute) Changes in food intake GI symptoms (N, V, D, anorexia) Functional impairment Examination Loss of SC fat (chest, triceps) Muscle wasting (temporal, deltoid, gluteal) Oedema Ascites
Nutritional Requirements Harris Benedict Equation – For the calculation of BMR (kcal/day) – BMR for a healthy, afebrile individual –≈ 25 kcal/kg/day Also the Schofield Equation Male BMR = (13.75 × wgt) + (5 × hgt) – (6.78 × age) + 66 Female BMR = (9.56 × wgt) + (1.85 × hgt) – (4.68 × age) + 655
Nutritional Requirements Harris Benedict Equation – For the calculation of BMR (kcal/day) – BMR for a healthy, afebrile individual –≈ 25 kcal/kg/day Fever: 10% for each 1°C above 37°C Sepsis: 9% (irrespective of T°C) Surgery: 6% if post trauma or surgery
Critical Illness and Requirements Acute critical illness – Catabolism > anabolism – CHO are preferred energy source (fat mobilisation is impaired) – Aim of nutritional support to minimise muscle protein breakdown – Acute initial phase of critical illness 20-25kcal/kg/day Recovery phase – Anabolism > catabolism – Nutritional support provides substrates for: correction of hypoproteinaemia Reparation of muscle loss Replenishes nutritional stores – Recovery/anabolic phase 25-30kcal/kg/day
Nutritional Requirements Macronutrients Provide energy – Protein: 5.3 kcal/g – Lipid: 9.3 kcal/g – Carbohydrate: 3.75 kcal/g Micronutrients Required in small amounts to maintain health but do not provide any energy
Protein Requirements 1.5 g kg -1 day -1 6.25 g contains 1 g of nitrogen ~ 0.20g nitrogen/kg/day. Nitrogen losses are large in critically ill patients Nitrogen output = urinary urea/mmol/24 hours x 0.033 + obligatory losses + extra renal losses Obligatory losses – estimated as 2-4g nitrogen/day (skin, hair, faeces etc) Extra renal losses include: – Pyrexia – Inflammatory bowel disease – GI fistulae – Extensive bed sores – Burn exudates
Protein Requirements in Specific Conditions Renal failure – Haemofiltration associated with increased protein losses (~10%) Liver failure – Protein requirements dependent on underlying function of the liver: Compensated cirrhosis 0.19-0.20gN/kg/day Decompensated cirrhosis 0.25-0.30gN/kg/day Post-transplant 0.25-0.30gN/kg/day Acute (fulminant) liver failure 0.20-0.25gN/kg/day
Lipid Requirements Lipid – Limit to 40% of calorie intake – Critically ill patients require approximately 0.8- 1.0g/kg/day of lipid. – NB: propofol is a lipid source Each ml contains of 1% propofol contains 0.9kcal and can increase the risk of both fat and total calorie overfeeding and micronutrient deficiency
Carbohydrate Requirements Carbohydrate – Excess intake above this can result in: hyperglycaemia lipid synthesis increased carbon dioxide production Carbohydrate + O 2 = water + CO 2 + energy production
Micronutrient Requirements Vitamins – Organic molecules essential for life; not synthesised by higher organisms – Fat-soluble: A, D, E, K – Water-soluble: C, B complex Minerals – Single elements essential to life: Ca, P, Mg, Zn, Fe, I Trace elements – Essential to life, but in minute quantities: Cu, Co, Mn, Ni, Mo, Cr
Micronutrient Requirements No set levels for micronutrient requirements for the critically ill – aim for the normal recommended daily allowance Specific disease states – Thiamine deficiency in alcoholics – Vitamin B 12 deficiency in patients post gastrectomy or total ileal resection – Zinc losses from pancreatic fistulae – Phosphate, magnesium and potassium deficiencies upon refeeding a malnourished patient Micronutrient supplementation in patients with renal failure needs to be undertaken cautiously due to risks of toxicity.
Feeds Standard formulation suitable for most patients – Isotonic – Lactose-free – Protein – Mixture of simple/complex CHO – Long-chain fatty acids – Micronutrients – Pro-biotics Variety of formulations available: – Concentrated for fluid restriction – Pre-digested for enzyme deficiencies
Enteral Nutrition Continuous vs bolus – No difference in mortality, infection, ITU LoS Monitoring – Measurement of gastric residuals to minimise risk of accumulation and aspiration – This is shown to correlate poorly with aspiration, and disrupts absorption. – Consensus towards only measuring residual if clinically indicated.
Parenteral Nutrition Contains a carefully formulated mixture of macronutrients, and fluid – Can be used to provide 100% of patient’s requirements Varying formulations (protein/lipid ratios depending on patient requirement) Minerals and trace elements are added to the bag by the pharmacy.
Initiation of PN Deliver via central venous route – High osmotic load poorly tolerated by peripheral veins <30d CVC, PICC >30d tunneled lines: Groshong, Hickman Dedicated port – Risk of infection
Monitoring Strict input/output measurement Daily electrolytes, until regime fully established LFTs, and triglycerides once a week
When to Start? Early provision (<48h) of PN to well-nourished patients does not alter mortality Early PN in well nourished patients may be associated with increased risk of infection (by 5%), even if EN is contraindicated. Higher incidence of hypoglycaemia in late PN Koretz RL, Lipman TO, Klein S, American Gastroenterological Association. AGA technical review on parenteral nutrition. Gastroenterology 2001; 121:970. Kerrie et al. Early versus late parenteral nutrition in the adult ICU: feeding the patient or our conscience? J Can Anesth (2012) 59:494–498
Glutamine Precursor for nucleotide synthesis – Important fuel source for new cells (e.g. GI mucosa) – Therefore helps maintain gut mucosal function, integrity and immune function Also has anti-oxidant actions which were thought to be useful in critical illness: however, REDOX trial suggests an increase in 28-day mortality. Heyland et al. A Randomized Trial of Glutamine and Antioxidants in Critically Ill Patients. NEJM 368;16 1489-1497
Complications Bloodstream infection Metabolic abnormalities – hyperglycemia – serum electrolyte alterations – macro- or micro-nutrient excess or deficiency, refeeding syndrome – Wernicke's encephalopathy – hepatic dysfunction Problems related to venous access
Results from rapid changes in fluids and electrolytes Pathophysiology based on total/partial starvation followed by refeeding Occurs in up to 35% of ITU patients Life-threatening, especially if associated with thiamine deficiency Mehanna HM, Moledina J, Travis J. Refeeding syndrome: what it is, and how to prevent and treat it. Br Med J 2008; 336:1495 – 1498.
Refeeding Syndrome Defined primarily by manifestations of severe hypophosphataemia – Cardiovascular collapse – Respiratory failure – Rhabdomyolysis – Seizures – Delirium Hypokalaemia Hypomagnesaemia
Identifying at-risk patients One or more criteria – BMI below 16 – Unintentional weight loss >15% in 3–6 months – Little or no nutrient intake for more than 10 days – Low potassium, phosphate, magnesium before feeding. Two or more criteria – BMI below 18.5 – Unintentional weight loss >10% in 3–6 months; – Little or no nutrient intake for more than 5 days; – History of chronic drug (insulin, diuretics, antacids) use or alcohol misuse. NICE CG32: Nutrition Support in Adults; February 2006
During critical illness: – Marked catabolic process – Increase in BMR – Relative insulin resistance Malnutrition associated with impaired immune function and increased morbidity Early recognition and correction of nutritional status is crucial
ESPEN Guidelines Patients should be fed because starvation or underfeeding in ICU patients is associated with increased morbidity and mortality All patients who are not expected to be on normal nutrition within 3 days should receive PN within 24 - 48 hours if EN is contraindicated or not tolerated. Singer et al. ESPEN Guidelines on Parenteral Nutrition: Intensive care. Clinical Nutrition 28 (2009) 387–400
Summary of Daily Requirements Calories25 kcal/kg Protein0.25 g N 2 /kg Glucose2 g/kg Fat2 g/kg Water30 mL/kg Sodium1.2 mmol/kg Potassium0.8 mmol/kg
Smith T, Pinnock C, Lin T. Fundamentals of Anaesthesia, 3 rd Edition; 2009. Cambridge: Cambridge University Press. Wellesley H. Nutrition in ICU, 2007. http://www.frca.co.uk/article.aspx?articleid=100979# accessed 26.06.13 http://www.frca.co.uk/article.aspx?articleid=100979# Macdonald K, Page K, Brown L, Bryden D. Parenteral nutrition in critical care. Continuing Education in Anaesthesia, Critical Care & Pain, 2012; 13(1): 1-5 Campbell Edmondson W. Nutritional support in critical care: an update. Continuing Education in Anaesthesia, Critical Care & Pain, 2007; 7(6): 199-202 Uptodate.com (accessed 28.06.13) Nutritional support in critically ill patients: parenteral nutrition Nutritional support in critically ill patients: enteral nutrition Nutritional support in critically ill patients: an overview