Nutrition and Immunonutrition in ICU

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  • 1. NUTRITION and IMMUNONUTRITION in the ICU Marcia McDougall October 2007

2. A slender and restricted diet is always dangerous in chronic and in acute diseases Hippocrates 400 B.C. 3. 4. Critical Illness

  • Heterogeneous patients
  • Extreme physiological stress/organ failure
  • Acute phase response: TNF, IL-6, IL-1
  • Immuno-suppression: monocytes, M , NK cells, T and B lymphocytes
  • Insulin resistance: hyperglycaemia
  • Protein loss and fat gain in muscle
  • Impaired gut function

5. Consequences of malnutrition

  • Increased morbidity and mortality
  • Prolonged hospital stay
  • Impaired tissue function and wound healing
  • Defective muscle function, reduced respiratory and cardiac function
  • Immuno-suppression, increased risk of infection
  • CIPs lose around 2%/day muscle protein

6. Scale of the problem

  • McWhirter and Pennington 1994:
  • >40% of hospital patients malnourished on admission
  • Recent Scottish data 35%
  • Estimated cost to hospitals: 3.8bn/yr
  • Many ICU patients malnourished or at risk on ICU admission

7. ICU Nutrition in the 1970s 8. ICU Nutrition through the ages Overfeeding 1980s 9.

  • 1970s: TPN - separate CH, AAs and Lipids
  • 2500-3000kcals/day: Lactic acidosis, high glucose loads, fatty livers, high insulin reqt
  • Single lumen C/Lines, no pumps
  • Urinary urea measured, N calculated
  • 1980s: Scientific studies of metabolism: recognition of overfeeding
  • 1990s: nitrogen limitation: 0.2g/kg/24hr, start of immunonutrition trials
  • 2000s: glucose control, specific nutrients

10. Nutrition trials in ICU

  • Small, underpowered
  • Heterogeneous and complex patients
  • Mixed nutritional status
  • Different feeding regimens
  • Underfeeding failure to deliver nutrients
  • Overfeeding adverse metabolic effects
  • Hyperglycaemia
  • Scientific basis essential

11. What is the evidence in ICU?

  • Early enteral feeding is best
  • Hyperglycaemia/overfeeding are bad
  • PN meta-analyses controversial
  • Nutritional deficit a/w worse outcome
  • EN a/w aspiration and VAP, PN infection
  • EN and PN can be used to achieve goals
  • Protocols improve delivery of feed
  • Some nutrients show promising results

12. Unanswered questions

  • Should we aim for full calorific delivery ASAP using EN + PN?
  • What are the best lipids to use in PN?
  • What is the role of small bowel feeding?
  • Are probiotics helpful?
  • Which patients will benefit from immuno-nutrition?
  • The future: targeted Nutrition Therapy?

13. Current practice - Scotland

  • SICS Nutrition Survey 2005-2006
  • Wide variation in PN and NJ feeding use
  • Wide variation in opinions about nutrition
  • Lack of education about nutrition
  • Lack of interest from clinicians
  • Nutrition teams in 11/24 hospitals (QIS)
  • Discussion between dietitians and doctors limited

14. % patients receiving PN/year 15. NJ feed: patient use per year 16. What is the maximum amount of time an ICU patient should go without nutrition? 17. Nutrition QI Study

  • Canadian Critical Care Network
  • 156 units cf CCCN guidelines
  • 8 Scotland, 22 UK
  • Adequacy of EN
  • Use of PN
  • Use of Immunonutrition
  • Protocols/Glycaemic control/Bed elevation

18. 19. Guidelines 20. systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstancesU.S. Institute of Medicine EBM - the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patientsSackett DL et al. BMJ 1996 21. What Guidelines are available?

  • Canadian Critical Care Network 2003/2007: Clinical Practice Guidelines
  • ICS: Practical Management of Parenteral Nutrition in Critically Ill Patients 2005
  • ESPEN: Enteral Nutrition 2006
  • NICE: Nutrition Support in Adults 2006

22. Organisation of Nutrition Support 3. NICE Guidelines for Nutrition Support in Adults 2006 Screen Recognise Treat Oral Enteral Parenteral Monitor & Review 23. Screen

  • Various nutritional screening tools
  • NRS 2002, SGA, MNA
  • Malnutrition Universal Screening Tool from the Malnutrition Advisory Group of BAPEN
  • Low risk: routine clinical care,
  • Medium risk: observe
  • High risk: treat- refer to dietitian/local protocols

24. Screening in ICU

  • MUST not very helpful in guiding decisions
  • Almost all patients require artificial nutrition- cannot observe
  • What about refeeding syndrome?
  • Needs adaptation using NICE Guidelines
  • Adapted MUST for ICU: Uses BMI/weight loss/food intake + refeeding risk assessment; linked to feeding flowchart

25. Step 3 Treat: Enteral use the most appropriate route of access and mode of delivery has a functional and accessible gastrointestinal tract if patient malnourished/at risk of malnutrition despite the use of oral interventions and 3. NICE Guidelines for Nutrition Support in Adults 2006 26. Step 3 Treat: PN and has either introduce progressively andmonitor closely if patient malnourished/at risk of malnutrition a non-functional,inaccessible or perforated gastrointestinal tract inadequate or unsafe oralor enteral nutritional intake use the most appropriate route of access and mode of delivery3. NICE Guidelines for Nutrition Support in Adults 2006 27. Routes Of feeding 28. REDUCED ENTERAL STIMULATION

  • DECREASED:
  • Peyers patch leukotrienes + MAdCAM-1
  • T & B cells in Peyers patches, Lamina propria & epithelium
  • Reduced secretory IgA and altered cytokines
  • Mucosal atrophy
  • Altered flora
  • Decreased gastric acid
  • Bacterial translocation

29. Enteral

  • Preserves intestinal mucosal structure and function
  • More physiological
  • Relatively non-invasive
  • Reduced risk of infectious complications cf PN (?)
  • Relatively cheap

30. NG problems

  • Risk of microaspiration in ICU
  • Risk of displacement
  • High gastric aspirates with opioids, sepsis, electrolyte imbalances
  • Reaching goals uncommon
  • PEG/gastrostomy feeding for long-term >4 weeks

31. Jejunal Feeding

  • Insertion
  • Surgical jejunostomy: at laparotomy
  • May reduce incidence of aspiration
  • Sometimes increases dose of EN given over NG
  • Indications

32. Parenteral Nutrition

  • GI tract not functional
  • GI tract cannot be accessed
  • Inadequate enteral nutrition 10)
  • Hx alcohol abuse or drugs including insulin, chemotherapy, antacids or diuretics
  • (Critically low levels of PO 4 2- , K +and Mg 2+)

40. Managing refeeding problems

  • provide Thiamine/multivitamin/trace element supplementation
  • start nutrition support at 5-10 kcal/kg/day
  • increase levels slowly
  • restore circulatory volume
  • monitor fluid balance and clinical status
  • replace PO 4 2- , K +and Mg 2+
  • Reduce feeding rate if problems arise

NICE Guidelines for Nutrition Support in Adults 2006 41. IMMUNONUTRITION Human Evolution

  • No ambulances/hospitals
  • First 72 hours after severe illness or injury crucial
  • Little hope of survival past this; not desirable
  • Significant stores of stress substrates not necessary e.g. glutamine

42. The Immune System

  • A complex and interactive biological system that coordinates the detection, destruction and elimination of any foreign material or organism entering the body.
  • Oxidants: cytokines, NFkB, genes, inflam n
  • Nutrients: glutamine, FFAs, protein
  • Glutathione: oxidant defence
  • Anti-inflammatory molecules: attenuation

43. Critical Illness

  • Sepsis: Battle between inflammatory response and microbes/toxins
  • Trauma: SIRS to non-infectious insult
  • Minor insult: inflammatory response wins
  • Major insult: with support (antibiotics, fluids) body may be able to fight insult but in severe insult inflammatory response continues and causes organ damage, f/b immune paresis and 2 infection; death

44. THE ICU GAMBLE How to tip the scales? Inflammation,organ failure Inflammation and resolution DEATH LIFE DISABILITY 45. Critical Illness

  • Small reductions in mortality over years
  • Increasing problems with infection
  • Advances in treatment have limited effects
  • Pathophysiology complex
  • The future: replacement of the bodys own stress substrates
  • Could immunonutrition be the most important area in critical care development?

46. Failed ICU strategies

  • Anti-TNF antibodies
  • Steroids in sepsis recent work suggests little effect
  • NO synthetase inhibitor: increased mortality
  • ??? Activated protein C - controversial

47. Immuno/Pharmaconutrition

  • Disease-modulating nutrients
  • Attenuate metabolic response
  • Prevent oxidant stress
  • Favourably modulate immune response
  • Probiotics to alter gut environment
  • Glycaemic control: keep blood glucose oxidation
  • Acute stress: injury/sepsis causes acute dysregulation: ROS/RNOS formed
  • Mitochondria are both sources and targets
  • Observational studies: anti-oxidant capacity inversely correlated with disease severity due to depletion during oxidative stress

REDUCTION OXIDATION 64. Reactive Oxygen Species O - , NO -

  • Positive actions:
  • Bactericidal
  • Regulation of vascular tone
  • Cell signalling
  • But mostly detrimental:
  • Cell injury (ischaemia /reperfusion)
  • DNA, Lipids, Proteins
  • Organ dysfunction
  • Lungs, Heart, Kidney
  • Liver, Blood, Brain

OXIDATION REDUCTION 65. ACUTE INSULT Exacerbation of cell and tissue injury Inflammatorymediators ROS/RNOS Healing/repair/defence 66. Antioxidants

  • Glutathione, Vitamins A, C and E
  • Zinc, copper, manganese, iron, selenium
  • Already added to feeds
  • Should we give extraCCCN consider
  • Results of SIGNET and REDOXs awaited
  • Oxidative stress in critically ill patients contributes to organ damage / malignantinflammation

67. Which Nutrient for Which Population? Canadian Clinical Practice GuidelinesJPEN 2003;27:355 Recom-mend Omega 3 FFA Consider Anti-oxidants EN Possibly Beneficial: Consider EN Possibly Beneficial: Consider PN Beneficial Recom-mend Possible Benefit Glutamine No benefit No benefit (Possible benefit) Harm(?) No benefit Benefit Arginine Acute Lung Injury Burns Trauma Septic General Elective Surgery Critically Ill 68. Immunonutrition- the future?

  • The right nutrient or combination
  • Correct dose
  • The appropriate timing
  • The right patient and circumstance
  • The appropriate assessment of efficacy
  • Balance between harm and benefit of the immune response
  • ?? Nutrient-gene interactions

69. Now

  • More & better trials of Immunonutrition
  • Early PN supplementation trial
  • Meanwhile: the basics- screening, reaching goals, protocols, refeeding
  • HDU feeding
  • Profile of Nutrition: Education, dialogue
  • Funding

70. Maintains Stimulatesthe environment defences

  • FEEDING
  • Provides energy