Nutrition in Critically ill

• Critically ill patients


  Have complex nutritional needs and require intensive nutritional input
• Metabolic response to injury

  1. Resting energy expenditure may be raised

  2. Extensive catabolism

  3. Hyperglycaemia

  4. Progressive lean body mass loss

  5. Changes in serum trace element levels

  6. Fluid retention

  7. Reduced synthesis of visceral proteins such as albumin
• Severe malnutrition causes widespread organ dysfunction and increases peri-operative morbidity and mortality rates
• Unwanted clinical sequelae of catabolism combined with malnutrition

  • Impaired wound healing
  • Impaired immune response
  • Impaired coagulation capacity
  • Impaired gut function
  • Muscle wasting
  • Reduced respiratory muscle function
• Goal of feeding ICU patients

  Provide nutrition support to those who need it, consistent with their medical condition, nutritional status, metabolic capability and available route of administration
• Survival from intensive care was improved with better nutritional adequacy and with the use of evidence-based nutrition support guidelines
• Total energy requirements


  Vary widely and depend on the basal metabolic rate, specific dynamic action, and a person's activity level
• Basal metabolic rate (BMR)


  Energy expenditure measured in the morning immediately after awakening, 12 h after the last meal, and in a state of thermal neutrality
• Basal energy expenditure (BEE)


  Can be estimated by the Harris-Benedict equation, using weight in kilograms, height in centimetres, and age in years
• BEE is increased by temperature (13% per °C), and degree of stress
• Nutritional assessment of critically ill patients

  Evaluation of nutritional status is central to nutritional support
• Nutritional assessment


  1. Take history to detect weight loss, dietary habits, and symptoms of hypoproteinemia

  2. Examine patient for evidence of loss of skeletal mass or fat stores, oedema or jaundice

  3. Classify patient as normally nourished or mildly or severely malnourished
• Patients requiring close assessment

  • Those with less than 80% acceptable body weight
  • Those with weight loss exceeding 10% in the preceding 6 months
  • Those with serum albumin <3 g/dL or serum transferrin < 150 mg/dL
  • Those with skin anergy
  • Those with low total lymphocyte count (<1200 cells/uL)
• Role of intensive care dietitian

  Central to the provision of nutrition support to those patients in need of it, and is ideally placed to provide nutritional screening and assessment
• Dedicated dietetic staffing to ICU has been associated with better provision of nutrition support and may result in improved patient outcomes
• Nutritional screening


  1. All ICU admissions should be screened to assess their need for nutrition support

  2. Recommend nutrition support within 24 to 48 hours of ICU admission (or once haemodynamically stable) for undernourished or hypercatabolic patients, ill patients expected to stay in ICU for 3 days or more, and patients not expected to commence diet within next 5 days or more
• Nutritional assessment before initiation of feeding

  Consider recent weight loss, nutrient intake prior to admission, level of disease severity, co-morbid conditions, and function of gastrointestinal tract
• In the critical care setting, the traditional protein markers such as albumin, prealbumin, transferrin and retinol binding protein are a reflection of the acute phase response and do not accurately represent nutritional status in the ICU setting
• Requirements should be assessed individually and provided according to tolerance
• Refeeding syndrome


  A life threatening condition that may result from over-rapid or unbalanced nutrition support provision to malnourished patients
• Effects of refeeding syndrome

  • Severe hypophosphataemia (whole body depletion)
  • Fluid balance abnormalities (acute overload/depletion)
  • Hypokalaemia
  • Hypomagnesaemia
  • Altered glucose metabolism
  • Vitamin deficiency
  • Cardiac failure, pulmonary oedema and dysrhythmias
  • Risk of death
• Patients at risk of refeeding syndrome

  • People who have not eaten for more than 5 days
  • BMI less than 16 kg/m2
  • Unintentional weight loss greater than 15% within the last 3–6 months
  • Little or no nutritional intake for more than 10 days
  • Low levels of potassium, phosphate or magnesium prior to feeding
  • BMI less than 18.5 kg/m2
  • Unintentional weight loss greater than 10% within the last 3–6 months
  • Little or no nutritional intake for more than 5 days
  • A history of alcohol abuse, or drugs including chemotherapy
• Nutrition support in patients at high risk of refeeding syndrome

  1. Start nutrition support at ≤10 kcal/kg/day, increase levels slowly to meet or exceed full requirements by day 4 to 7

  2. Restore circulatory volume and monitor fluid balance and overall clinical status closely

  3. Give a balanced multivitamin/trace element supplement once daily

  4. Provide oral, enteral or intravenous supplements of potassium, phosphate and magnesium unless pre-feeding plasma levels are high (in accordance with local hospital policies/protocols on electrolyte replacement)
• Enteral feeding


  The preferred route of feeding for ICU patients
• Enteral feeding helps to maintain gut integrity, prevent gut stasis, maintain gut mass, maintain gut associated lymphoid tissue, and prevent stress ulceration
• Early enteral feeding (within 24-48 hours of ICU admission) benefits ICU patients
• Acceptable gastric residual volume levels

  Between 250 and 500ml have been advocated for ICU patients
• Feed administration guidelines


  1. Use closed enteral feeding systems where possible

  2. Change administration sets per manufacturer guidelines for closed systems, and at least every 24 hours for open systems

  3. Use sterile water for flushing tubes or for enteral water infusion, and flush feeding tubes regularly

  4. Use sterile liquid formulas in preference to powdered reconstituted feeds
• Strategies to improve enteral feeding tolerance

  1. Consider use of prokinetics e.g. metaclopramide and/or erythromycin, unless contraindicated

  2. Routine use of prokinetics is not recommended unless signs of feed intolerance are present

  3. Consider use of laxatives if no bowel motion, where there is no contraindication

  4. Reduce use of opiates where possible

  5. Ensure head of patient is elevated to 30 to 45 degrees, where possible

  6. Consider post-pyloric access for feeding

  7. Control hyperglycaemia if present

  8. Correct abnormal electrolytes and avoid hypokalaemia, where possible
• Routine nasojejunal feeding in ICU patients

  Not required unless gastric feeding intolerance is present
• Monitoring post-pyloric feeding


  1. Monitor pH, changes in external tube length, and changes in gastric residuals

  2. Check X-rays to confirm location of feeding tube tip initially, and as needed
• Total Parenteral Nutrition (TPN)


  The administration of a nutritionally adequate hypertonic solution consisting of dextrose, amino acids, protein, minerals, fats, vitamins and trace elements through an intravenous catheter
• Indications for TPN administration


  • Small bowel ileus
  • High output fistula >500 mls/day
  • Mechanical small bowel obstruction
  • Bowel infarction/bowel ischemia
  • Inability to tolerate enteral feeding
• Composition of TPN solutions

  • Lipids: One solution – 10% or 20%
  • Electrolytes: Na, K, Ca, PO4, Mg, Cl, Acetate
  • Vitamins: MVI-12
  • Minerals: Zinc, copper, manganese, selenium, chromium
• Low concentration TPN solutions

  < 10% dextrose, Amino Acids, usually through 18 gauge [pink] angiocath
• High concentration TPN solutions

  > 10% dextrose, Amino Acids, through PICC, CVC site ONLY
• Access routes for TPN administration

  • Peripheral Lines: Arm veins, TPN expected to run < than 2 weeks, for < 10% dextrose solution ONLY
  • Central Venous Catheters: Subclavian or internal jugular vein catheterized, used when peripheral veins are unsuitable or patient requires high concentration solution
  • Peripherally Inserted Central Catheters (PICC): Inserted into the basilic or cephalic vein then threaded up toward the heart into the right subclavian vein, TPN expected to run > 1 wk, can infuse either central or peripheral solution
• Peripheral parenteral nutrition


  When a 3-4% amino acid solution is added to a 5-10% dextrose solution, the resulting solution is still hypertonic but can be generally infused through a peripheral vein without irritation, maximum calories intake by this route is 800-1200 kcal/d
• Complications of total parenteral nutrition

  • Catheter-related: Pneumothorax, Hemothorax, Chylothorax, Air embolism, Cardiac tamponade, Thrombus, Catheter sepsis
  • Metabolic: Azotemia, Hepatic dysfunction, Cholestasis, Hyperglycemia, Excessive CO2 production, Hypoglycemia, Hypekalemia, Hypokalemia, Hypocalcemia, Hypophosphatemia, Hyperlipidemia, Pancreatitis, Fat embolism syndrome, Anaemia, Vitamin D deficiency, Vitamin K deficiency, Hypervitaminosis A, Hypervitaminosis B