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Nutrition in Intensive Care
This document summarizes key considerations for nutrition in intensive care patients. It addresses questions like which patients should be fed, when feeding should start, what route is best, how much to feed, and what the feed should contain. The document discusses evidence that early enteral feeding within 48 hours is preferable to delaying feeding. It also notes that enteral feeding is generally better than parenteral feeding when possible due to lower risks, though parenteral may be necessary in some cases. The optimal amount of feeding is also addressed.
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Introduction to nutrition in intensive care, resources for information and downloads available.
Importance of feeding ICU patients to treat malnutrition and minimize lean body mass loss; questions regarding patient feeding.
Need for early feeding within 48 hours, preference for enteral feeding due to benefits, pragmatic approaches.
Issues related to enteral feeding and TPN complications including infections, metabolic imbalances.Energy needs and amounts recommended for ICU patients including protein and caloric intake.
Nutritional management in renal, liver, and respiratory failure, along with the role of glutamine.
Effects of immunonutrition including glutamine, selenium, and omega-3 fatty acids on ICU outcomes.
Recap of feeding rationale, patient selection, onset of feeding, preferred routes, and nutrient composition.
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Nutrition in Intensive Care
- 1. Nutrition in IntensiveCare Richard Leonard St Mary’s Hospital, London
- 2. Slides and summarywww.st-marys-anaesthesia.co.uk ICU Downloads
- 3. Resources www.evidencebased.net www.criticalcarenutrition.com ACCEPT study Martin, CM et al CMAJ 2004;170:197-204 cluster RCT of nutrition algorithms intervention ICUs had lower mean hospital LOS 10% reduction in ICU mortality but p=0.1 no difference in attainment of most nutritional targets
- 4. Six simple questionsWhy do we feed ICU patients? Which patients should we feed? When should we start to feed them? Which route should we feed by? How much feed should we give? What should the feed contain?
- 5. Why feed ICUpatients? few data directly compare feeding with no feeding – two trials and one meta-analysis suggest worse outcomes in un(der)fed patients catabolism of critical illness causes malnutrition malnutrition closely associated with poor outcomes many ICU patients are malnourished on admission
- 6. Aims of feedingICU patients treat existing malnutrition minimise (but not prevent) the wasting of lean body mass that accompanies critical illness
- 7. Nutritional assessment importantto identify existing malnutrition clinical evaluation is better than tests history weight loss, poor diet, reduced function examination loss of subcutaneous fat, muscle wasting, peripheral oedema, ascites
- 8. Which patients shouldwe feed? which patients can safely be left to resume feeding themselves? 14 days’ starvation - dangerous depletion of lean body mass mortality rises in ICU patients with a second week of severe under-feeding 5 days without feed increases infections but not mortality one view is therefore that 5-7 days is the limit
- 9. Which patients shouldwe feed? however ACCEPT study fed all patients not likely to eat within 24 hours one meta-analysis suggests reduced infections if patients are fed within 48 hours one meta-analysis of early TPN versus delayed EN found reduced mortality with early feeding
- 10. Which patients shouldwe feed? all malnourished patients all patients who are unlikely to regain normal oral intake within either 2 or 5-7 days depending on your view
- 11. When should westart to feed? early feeding usually defined as starting within the first 48 hours of admission meta-analysis suggests reduced infections if patients are fed within 48 hours meta-analysis of early TPN versus delayed EN found reduced mortality with early feeding ACCEPT study aimed to start within 24 hours of ICU admission
- 12. When should westart to feed? surgical issues gastric, duodenal or high small bowel anastomoses critical mesenteric ischaemia
- 13. When should westart to feed? without undue delay once the patient is stable this will usually be within 48 hours of ICU admission
- 14. What route shouldwe feed by? enteral feeding is claimed to be superior because it prevents gut mucosal atrophy it reduces bacterial translocation and multi-organ failure lipid contained in TPN appears to be immuno-suppressive
- 15. Is enteral feedingreally better? mucosal atrophy occurs far less in humans TPN is associated with increased gut permeability bacterial translocation does occur in humans and may be associated with infections increased gut permeability never shown to cause translocation translocation has never been shown to be associated with multi-organ failure enteral nutrition has never been shown to prevent translocation
- 16. Outcome evidence doesEN reduce infections? pancreatitis - probably abdominal trauma - probably (2 trials of 3) head injury - evenly balanced other conditions – no clear conclusion Lipman reviewed 31 trials and found no consistent effect meta-analysis by Heyland et al found reduced infections EN is definitely a risk factor for VAP
- 17. Outcome evidence doesroute of feeding affect mortality? Heyland’s meta-analysis showed no effect on mortality Doig and Simpson’s more robust meta-analysis found TPN reduced mortality when TPN and EN were directly compared; TPN versus early EN showed no difference
- 18. What route shouldwe feed by? enteral feeding is cheaper easier and therefore preferable in most cases parenteral feeding is obviously necessary in some
- 19. A pragmatic approachWoodcock and MacFie Nutrition 2001 serious doubt about viability of enteral feeding within 7 days randomised to EN or TPN EN group no reduction in infections higher incidence of under-feeding and feed-related complications
- 20. What route shouldwe feed by? EN preferred for majority on pragmatic grounds alone TPN obviously necessary for some if there is serious doubt that EN can be established in a reasonable time (ACCEPT study used 1 day; others would use 2 or 5 or 7…) commence TPN maintain at least minimal EN keep trying to establish EN
- 21. Enteral feeding underfeedingis a serious problem NJ tubes probably do not reduce VAP probably increase proportion of target delivered prokinetic agents of unproven efficacy PEGs are not advisable in acutely ill patients
- 22. Diarrhoea use fibre-containingfeed avoid drugs containing sorbitol and Mg exclude and treat Clostridium difficile infection faecal impaction consider malabsorption (pancreatic enzymes, elemental feed) lactose intolerance (lactose-free feed) using loperamide
- 23. TPN - complicationscatheter-related sepsis no benefit from single lumen catheters hyperchloraemic metabolic acidosis electrolyte imbalance - low Pi, K, Mg refeeding syndrome abnormal LFTs rebound hypoglycaemia on cessation deficiency of thiamine, vit K, folate
- 24. How much feedshould we give? overfeeding is useless - upper limit to amounts of protein and energy that can be used dangerous hyperglycaemia and increased infection uraemia hypercarbia and failure to wean hyperlipidaemia hepatic steatosis
- 25.
- 26. How much shouldwe feed? underfeeding is also associated with malnutrition and worse outcomes
- 27. How much feedshould we give? energy - 25 kCal/kg/day (ACCP) indirect calorimetry gold standard no evidence of benefit shows that other methods are inaccurate, especially as patients wean equations eg Schofield correct for disease, activity
- 28. How much feedshould we give? nitrogen no benefit from measuring nitrogen balance nitrogen 0.15-0.2 g/kg/day protein 1-1.25 g/kg/day severely hypercatabolic patients (eg burns) may receive up to 0.3 g nitrogen/kg/day
- 29. What should thefeed contain? carbohydrate 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
- 30. Nutrition in acuterenal failure essentially normal CVVHD/F has meant fluid and protein restriction are no longer necessary or appropriate
- 31. Nutrition and liverdisease chronic liver disease energy requirement normal lipolysis increased so risk of hypertriglyceridaemia protein restriction not normally needed, but in chronic encephalopathy intake should be built up from 0.5 g protein/kg/day BCAA -enriched feed may permit normal intake in the protein-intolerant acute liver failure gluconeogenesis impaired, so hypoglycaemia a risk
- 32. Nutrition in respiratoryfailure avoid overfeeding at all costs energy given as 50% lipid may reduce PaCO 2 and improve weaning, but unproven
- 33. Nutrition in acutepancreatitis transpyloric feeding shown to be safe reduce infection rate probably reduce mortality malabsorption may require elemental feeds and pancreatic enzyme supplements TPN no longer standard therapy - however, some patients do not tolerate enteral feeding
- 34. What else shouldthe feed contain? glutamine? selenium? immunonutrition?
- 35. Glutamine primary fuelfor enterocytes, lymphocytes and neutrophils; also involved in signal transduction and gene expression massive release from skeletal muscle during critical illness may then become ‘conditionally essential’ is not contained in most TPN preparations
- 36. Enteral glutamine reducesvillus atrophy in animals and humans reduced pneumonia and bacteraemia in two studies - multiple trauma, sepsis one much larger study (unselected ICU patients) showed no effect difficult to give adequate dose enterally probably not worth it
- 37. Parenteral glutamine Liverpoolstudy in ICU showed reduction in late mortality London study of all hospital TPN patients showed no benefit French trauma study showed reduced infection but no mortality effect German ICU study improved late survivial in patients fed for more than 9 days
- 38. Parenteral glutamine glutaminebecomes conditionally essential in critical illness and is not given in standard TPN parenteral supplementation appears to be beneficial in patients requiring TPN for many days
- 39. Selenium regulates free-radicalscavenging systems low levels common in normals and ICU patients several small studies inconclusive but suggest benefit one large, flawed recent study showed non-significant mortality benefit watch this space…
- 40. Immunonutrition omega-3 fattyacids produce less inflammatory eicosanoids arginine nitric oxide precursor enhances cell-mediated immunity in animals nucleotides DNA/RNA precursors deficiency suppresses cell-mediated immunity
- 41. Immunonutrition few studiesin ICU populations some found reduced infection in elective surgery one unblinded study has shown reduced mortality in unselected ICU patients; benefit in least ill (CCM 2000; 28:643) another showed increased mortality on re-analysis which barely failed to reach statistical significance (CCM 1995; 23:436)
- 42. Immunonutrition first meta-analysis(Ann Surg 1999; 229: 467) no effect on pneumonia reduced other infections and length of hospital stay increased mortality only just missing statistical significance did not censor for death second meta-analysis (CCM 1999; 27:2799) reduced infection reduced length of ventilation and hospital stay no effect on mortality
- 43. Immunonutrition third meta-analysis(JAMA 2001; 286:944) benefit in elective surgery increased mortality in ICU patients with sepsis large Italian RCT (ICM 2003; 29:834) compared enteral immunonutrition with TPN stopped early because interim analysis showed increased mortality in septic patients 44.4% vs 14.3%; p=0.039
- 44. Immunonutrition arbitrary dosesrandom mixture of agents mutually antagonistic effects diverse case mix individual components need proper evaluation
- 45. Why do wefeed ICU patients? to treat existing malnutrition to minimise the wasting of lean body mass that accompanies critical illness
- 46. Which patients shouldwe feed? all malnourished patients all patients who are unlikely to regain normal oral intake within 2 days
- 47. When should westart to feed? without undue delay once the patient is stable within 2 days
- 48. What route shouldwe feed by? EN preferred for majority on pragmatic grounds alone TPN obviously necessary for some if there is serious doubt that EN can be established in 2 (or 5, 7…) days commence TPN maintain at least minimal EN keep trying to establish EN
- 49. How much feedshould we give? 25 kCal/kg/day equations indirect calorimetry
- 50. What should thefeed contain? carbohydrate lipid nitrogen water and electrolytes micronutrients