AIMS OF NUTRITIONAL SUPPORT Provide exogenous substrates to meet micro and macro nutrient requirement in ICU patients. Help protect vital visceral organs and attentuate breakdown of skeletal muscle. Reduce net protein catabolism.
FACTORS ASSOCIATED WITH MALNOURISHMENT Chronic diseases like malignancy,kidney and liver diseases,Congestive heart failure. Digestive and absorptive abnormalities like inflammatory bowel disease,short bowel syndrome,gastrointestinal fistula,pancreatic disease,chronic diarrohoea. Social and dietary factors.i.e.Drug and alcohol abuse,poverty and poor dentation. Increased requirements as in burns,post-surgery, sepsis and chemotherapy patients. Critically ill patients and mechanically ventilated patients.
EFFECTS OF MALNUTRITION IN ICU OUTCOME: Impaired immunological function. Impaired ventilatory drive. Prolonged ventilator dependence. Increased infectious mortality and morbidity. Increased risk of complications. Poor wound healing. Increased length of ICU stay.
ESPEN CRITERIA FOR SEVERE UNDERNUTRITION: Atleast one of the criteria should be present: Subjective Global assessment Grade C.(evaluates abnormalities in food intake,digestion an absorption,strength and activity,and body composition). Developed by Detsky et al.Good senstivity and specificity. Serum albumin level <30gm/litre(with no evidence of hepatic or renal dysfunction. Weight loss of 10%-15% in period of 6 months.
NUTRITION AS A SOURCE OF ENERGY Basal Energy Expenditure (BEE) or BMR-The energy expenditure on awakening from a 12 hour fast measured in a thermoneutral environment(25 deg). Thermogenic Effect of Food(Specific Dynamic Action)-The energy exenditure after the ingestion of food.Increases by 5%-10% Sleeping Energy Expenditure-During sleep.Usually 10%-15% lower than REE.
Resting Energy Expenditure(REE)-Energy expenditure while resting in supine position with eyes open.Includes the thermogenic effects of food if performed within hours of a meal or during continous infusions of nutrients such as during TPN administration.10% greater than BEE. Activity Energy Expenditure(AEE)-During maximum exercise 6-10 fod greater than BEE. Fever increases metabolic rate by 10% per degree centigrade rise in temperature.
Estimating Resting Energy Expenditure(Harris-Benedict Equation)- Male eBEE(Kcal/day)=66+(13.7.W)+(5.H)-(6.8.A) Female eBEE(Kcal/day)=655+(9.6.W)+(1.7.H)-(4.7.A) eREE=eBEE.Stress factor eTEE=eREE.Activity factor
Measuring Energy Expenditure using Indirect Calorimetry Weir Equation=1.44(3.9.VO2)+(1.1VCO2) Measured with help of specialized instruments known as metabolic carts. Recommended method of measurement in critically ill patient* Limitations- Expensive equipment Patient should be on ventilator Oxygen sensor unreliable at inspired levels above 50% * Flancbaum et al.Comparison of indirect calorimetry,the Fick method and prediction equations in estimating the energy requirements of critically ill patients AJC Nutrition;1999;69:
Nitrogen Balance(as a measure of protein requirement)- Two thirds of nitrogen derived from protein breakdown is excreted in urine. Protein is 16%nitrogen-each gram of urinary nitrogen (UN) represents 6.25 gms of degraded protein. N Balance(gm)=(Protein intake(gm)/6.25)-(UUN+4) UUN=Urea Nitrogen excretion(gm) in 24 hrs The first step in achieving a positive nitrogen balance is to provide enough non protein calories to spare proteins from being degraded.
Calories can be provided in three forms- Carbohydrates- Provide 30%-70% of total calories. Commonly in form of glucose but sucrose,fructose are also used. Insulin maybe required to maintain tight sugar control(since Insulin resistance is seen in stress). Fat- 20%-50% of total calories. Critically ill patients utilize fat better than carbohydrates as energy source. Atleast 7% of total calories should be in form of omega-6- polyunsaturated fatty acid(PUFA) triglycerides. Medium and long chain triglycerides.
Proteins- 15%-20% total calories to be given as proteins.Administered as whole proteins or amino acids.
Stress factors- Spontaneously breathing non-sedated patients: Major surgery 15%-25% Infection 20% Long Bone fracture 20%-35% Malnutrition subtract 10%-15% Burns upto 120% depending upon extent Sepsis 30%-55% Major Trauma 20%-35% COPD 10%-15% Sedated mechanically ventilated patient subtract 10%-15%
ASSESSMENT OF NUTRITIONAL STATUS IN CRITICALLY ILL PATIENTS Body Mass Index (Anthropometric measure) Skinfold thickness and arm-muscle circumference. Creatinine height index Temporal wasting Signs of specific micronutrient deficiency. Albumin-protein nutritional status Prealbumin levels are a better indicator nutritional status. Hemoglobin levels Magnesium Phosphorus
CUTHBERTSON MODEL OF RESPONSE TO INJURY: Ebb phase-Period of severe shock,depression of enzymatic activity and oxygen consumption. Reduced cardiac output and presence of lactic acidosis. Flow catabolic phase-Fat and protein mobilization,increased urinary nitrogen excretion and weight loss. Flow anabolic phase-Restoration of fat and protein stores and weight gain.
HIGHER METABOLIC REQUIREMENTS: Burns Septic Shock Perfusion deficit Inflammation Necrotic tissues Head Injury and polytrauma
CALCULATION OF ENERGY REQUIREMENTS: As per ESPEN guidelines 2006 Acute initial phase of critical illness kcal/kg/day Recovery/anabolic phase kcal/kg/day
METHODS OF NUTRITIONAL SUPPORT Enteral feeds 1. Gastric feeds 2. Duodenal feeds 3. Jejunostomy feeds Total parenteral nutrition 1. Peripheral route 2. Central route
FORMULAS FOR FEEDING Carbohydrates EN:Oligo- and polysaccharides PN:Concentrated glucose Lipid EN:Long and medium chain triglycerides PN:soya bean oil,glycerol,egg phosphatides Nitrogen EN:intact proteins PN:Crystalline amino acid solutions Water and electrolytes Micronutrients
ROUTES OF ENTERAL FEEDING
INDICATIONS FOR ENTERAL NUTRITION Malnourished patients whose oral intake is poor for 3-5 days. Well nourished patients with poor oral intake for 7-10 days.Inadequately for whatever reason to eat adequately. Following massive bowel resection-enteral nutrition helps in regenaration of small bowel mucosa. Enterocutaneous fistulae with an output of <500 ml/day. Severe full thickness burns-limits sepsis and reduces protein loss from bowels.
Following major upper GI surgery Following surgery for necrotising,suppurative pancreatitis-intial TPN followed by jejunostomy feeds.
CLASSIFICATION OF ENTERAL FEEDS Liquidized or Blenderized Food-Liquid forms of table food. Lactose-free formulas-Patients with lactose intolerance eg.Isocal,Sustacal Chemically defined formulas-Hydrolysated protein to facilitate absorption.eg.criticare HN Elemental formulas-Contain aminoacids.Well absorbed in jejunum.
FEEDING FORMULAS Caloric density of feeding formulas determined by carbohydrates.Normally 1-2kcal/litre. Osmolality of liquid feeding formulas varies from Contain gm protein/per litre.High protein diet feeds also availaible. Lipid content of most formulas restricted to 30% of total calories. Other additives-Glutamine,dietary fibres,Branched chain amino acids,carnitine
COMPLICATIONS OF ENTERAL FEEDING Gastric retention,vomiting, and aspiration pneumonia. Diarrhoea Mechanical problems
INDICATIONS FOR PARENTRAL NUTRITION Non functioning gut e.g.paralytic ileus. Malnourished patients in whom the use of intestine is not anticipated for > 7 days after major abdominal surgery Severe mucositis following systemic chemotherapy, upper gastrointestinal strictures or fistulae and severe acute pancreatitis where jejunal feeding is contraindicated. In patients with major resections of small intestine (short bowel syndrome) before compensatory adaptation occurs.
COMPLICATIONS OF PARENTRAL NUTRITION Metabolic complications- Hyperglycemia or hypoglycemia Hypomagnesaemia Hypophosphataemia Hepatic dysfunction Catheter related- Catheter related sepsis Thrombosis of vein Technical complications Catheter related
NUTRITIONAL SUPPORT IN SPECIAL CONDITIONS RENAL FAILURE- To be started along with hemodialysis/hemofiltration. Non-dialysed patients protein intake restricted to 0.5g/kg/day.Fluid restriction litre/day if low urine output. Dialysed patient protein intake increased to 1g/kg/day. Incase of enteral feeding carbohydrate:fat ratio 60:40 During haemodialysis loss of 6-12g of amino acid per treatment & loss gm during a 6 hour dialysis. Haemofilration net loss of 4 gm aminoacids. Peritoneal dialysis net gain in glucose of gm/day.
Hepatic failure- If no encaphalopathy then protein-1gm/kg/day.If present then 0.3 gm/kg/day. Infusion of branched chain amino acids improves encaphalopathy. Caloric requirement of Glucose and fat in ratio 60:40 Total caloric requirement 25 kcal/kg/day.
Respiratory failure- Reduce carbohydrate intake to decrease carbon dioxide production especially when being weaned from ventilatory support. Carbohydrate:fat ratio 40:60;protein intake 1.2 gm/kg/day.Total caloric intake 25 kcal/kg/day. On the contrary patients with ARDS,lipid emulsions may interfere with gas exchange.Keep carbohydrate:fat ratio 65:35 when on parenteral nutrition.
Cardiac Failure- Restrict water and salt intake with careful monitoring of Na,K and Mg TPN to be started with half caloric requirement over 3-4 days in order to avoid pulmonary oedema secondary to refeeding and increased metabolic rate. Glucose:fat ratio 60:40
Pancreatitis- To start enteral jejunal feeds of peptide based diet unless patient having fulminant pancreatitis or in sepsis. Caloric intake of 25 kcal/kg/day with gm/kg/day of proteins.
Burns- Total caloric intake kcal/kg/day with gm/kg/day of proteins. Increased protein intake reduces morbidity and mortality. Prefered route enteral;maybe supplemented with TPN.
Pharmaconutrition:An emerging paradigm Specific nutrients found to have effects on immune system,metabolism and GI structure and functions. Glutamine Arginine Omega 3 fatty acids Anti-oxidants
ROLE OF IV GLUTAMINE WITH PARENTRAL NUTRITION Important immunonutrient derived from muscle protein breakdown. Increased consumption in catabolic states thereby leading to: Increased translocation of bacteria or bacterial toxins. Decreased activity of macrophages and killer cells in the intestinal wall. Increased risk of sepsis. Increased morbidity and mortality. Prolonged ICU stay.
Canadian Guidelines on Nutritional Support 2009 Strongly recommend enteral nutrition over parentral. Enteral nutrition to be commenced early(within hrs)in ICU patients unless contraindicated otherwise. When starting enteral nutrition strategies to optomize delivery of nutrients(starting at target rate,higher threshold of residual gastric volumes,use of prokinetics and small bowel feedings)should be considered. Not to use diet supplemented with Arginine When starting enteral feeds make use of whole protein formulas.
Reduced chances of pneumonia associated with small bowel feeding as compared to gastric feeding. Maintain tight blood sugar regime(as per NICE sugar study maintain between 7-9 mmol/litre). Consider supplementation of vitamins and trace elements. Role of Selenium and other anti-oxidants is doubtful.