NUTRITON AND METABOLIC STRESS

1. NUTRITON AND METABOLIC STRESS

2. Metabolic Stress • Sepsis (infection) • Trauma (including burns) • Surgery • Once the systemic response is activated, the physiologic and metabolic changes that follow are similar and may lead to septic shock.

3. Immediate Physiologic and Metabolic Changes after Injury or Burn ADH, Antiduretic hormone; NH3, ammonia.

4. Metabolic Response to Stress • Involves most metabolic pathways • Accelerated metabolism of LBM • Negative nitrogen balance • Muscle wasting

5. Ebb Phase • Immediate—hypovolemia, shock, tissue hypoxia • Decreased cardiac output • Decreased oxygen consumption • Lowered body temperature • Insulin levels drop because glucagon is elevated.

6. Flow Phase • Follows fluid resuscitation and O2 transport • Increased cardiac output begins • Increased body temperature • Increased energy expenditure • Total body protein catabolism begins • Marked increase in glucose production, FFAs, circulating insulin/glucagon/cortisol

7. Hormonal and Cell-Mediated Response • There is a marked increase in glucose production and uptake secondary to gluconeogenesis, and —Elevated hormonal levels —Marked increase in hepatic amino acid uptake —Protein synthesis —Accelerated muscle breakdown

8. Skeletal Muscle Proteolysis From Simmons RL, Steed DL: Basic science review for surgeons, Philadelphia, 1992, WB Saunders.

9. Metabolic Changes in Starvation From Simmons RL, Steed DL: Basic science review for surgeons, Philadelphia, 1992, WB Saunders.

10. Hormonal Stress Response • Aldosterone—corticosteroid that causes renal sodium retention • Antidiuretic hormone (ADH)—stimulates renal tubular water absorption • These conserve water and salt to support circulating blood volume

11. Hormonal Stress Response—cont’d • ACTH—acts on adrenal cortex to release cortisol (mobilizes amino acids from skeletal muscles) • Catecholamines—epinephrine and norepinephrine from renal medulla to stimulate hepatic glycogenolysis, fat mobilization, gluconeogenesis

12. Systemic Inflammatory Response Syndrome • SIRS describes the inflammatory response that occurs in infection, pancreatitis, ischemia, burns, multiple trauma, shock, and organ injury. • Patients with SIRS are hypermetabolic.

13. Multiple Organ Dysfunction Syndrome • Organ dysfunction that results from direct injury, trauma, or disease or as a response to inflammation; the response usually is in an organ distant from the original site of infection or injury

14. Diagnosis of Systemic Inflammatory Response Syndrome (SIRS) • Site of infection established and at least two of the following are present —Body temperature >38° C or <36° C —Heart rate >90 beats/minute —Respiratory rate >20 breaths/min (tachypnea) —PaCO2 <32 mm Hg (hyperventilation) —WBC count >12,000/mm3 or <4000/mm3 —Bandemia: presence of >10% bands (immature neutrophils) in the absence of chemotherapy-induced neutropenia and leukopenia • May be caused by bacterial translocation

15. Bacterial Translocation • Changes from acute insult to the gastrointestinal tract that may allow entry of bacteria from the gut lumen into the body; associated with a systemic inflammatory response that may contribute to multiple organ dysfunction syndrome • Well documented in animals, may not occur to the same extent in humans • Early enteral feeding is thought to prevent this

16. Bacterial Translocation across Microvilli and How It Spreads into the Bloodstream

17. Hypermetabolic Response to Stress—Cause Algorithm content developed by John Anderson, PhD, and Sanford C. Garner, PhD, 2000.

18. Hypermetabolic Response to Stress—Pathophysiology Algorithm content developed by John Anderson, PhD, and Sanford C. Garner, PhD, 2000.

19. Hypermetabolic Response to Stress—Medical and Nutritional Management Algorithm content developed by John Anderson, PhD, and Sanford C. Garner, PhD, 2000. Updated by Maion F. Winkler and Ainsley Malone, 2002.

20. NUTRITIONAL ASSESSMENT • Clinical judgment must play a major role in deciding when to begin/offer nutrition support

21. Determination of Nutrient Requirements • Energy • Protein • Vitamins, Minerals, Trace Elements • Nonprotein Substrate • Carbohydrate • Fat

22. Energy • Enough but not too much • Excess calories: • Hyperglycemia • Diuresis – complicates fluid/electrolyte balance • Hepatic steatosis (fatty liver) • Excess CO2 production • Exacerbate respiratory insufficiency • Prolong weaning from mechanical ventilation

23. Indirect Calorimetry • Better estimate in critically ill hypermetabolic patient • The “gold standard” in estimating energy needs in critical care • Can be used in both mechanically ventilated and spontaneously breathing patients (ventilated patients most accurate) • Equipment is expensive and not readily available in many facilities

24. Indirect Calorimetry • Requires appropriate calibration of equipment, attainment of a steady state for measurement, and appropriate timing of measurement • Requires interpretation by trained clinician • Inaccurate in patients requiring inspired oxygen (FiO2>60%), and with air leaks via the entrotracheal tube cuff, chest tubes or bronchopleural fistula

25. Indications for Indirect Calorimetry • Patients with altered body composition (underweight, obese, limb amputation, peripheral edema, ascites) • Difficulty weaning from mechanical ventilation • Patients s/p organ transplant • Patients with sepsis or hypercatabolic states (pancreatitis, trauma, burns, ARDS) • Failure to respond to standard nutrition support Malone AM. Methods of assessing energy expenditure in the intensive care unit. Nutr Clin Pract 17:21-28, 2002.

26. Nutrient Guidelines: Carbohydrate • Should provide 60 – 70% calories • Maximum rate of glucose oxidation = ~5 – 7 mg/kg/min or 7 g/kg/day* • Blood glucose levels should be monitored and nutrition regimen and insulin adjusted to maintain glucose below 150 mg/dl *ASPEN BOD. JPEN 26;22SA, 1992

27. Nutrient Guidelines: Fat • Can be used to provide needed energy and essential fatty acids • Should provide 15 – 40% of calories • Limit to 2.5g/kg/day or possibly 1 g/kg/day IV* • Caution with use of fats in stressed & trauma pts • There is evidence that high fat feedings (especially LCT) cause immunosuppression • New formulas focus on omega-3s *ASPEN BOD. JPEN 26;22SA, 1992

28. Nutrient Guidelines: Protein • 1.5 – 2.0 g/kg/day to start; monitor response • Nonprotein calorie/gram of nitrogen ratio for critically ill = 100:1 • Giving exogenous aa’s decreases negative N balance by supplying liver aa’s for protein synthesis ASPEN BOD. JPEN 26;22SA, 1992

29. Fluid and Electrolytes Fluid • 30-40 mL/kg or • 1 to 1.5mL/kcal expended Electrolytes/Vitamins/Trace Elements • Enteral feedings: begin with RDA/AI values • PN: use PN dosing guidelines ASPEN BOD. JPEN 26;23SA, 1992

30. Supplemental Glutamine (GLN) in Critical Care • Alterations in glutamine metabolism can occur in critical care, possibly affecting gut function • PN solutions traditionally have not contained glutamine because of instability in solution • Animal and human studies suggest that supplemental GLN in PN may have beneficial effects • Those benefits have not been demonstrated in EN

31. Glutamine Metabolism NH2, Amine; NH3, ammonia. From Simmons RL, Steed DL: Basic science review for surgeons, Philadelphia, 1992, WB Saunders.

32. MNT in Selected Populations in Critical Care

33. Acute Spinal Cord Injury Source: www.spinal-cord-injury-resources.com/ spinal-i...

34. Acute Spinal Cord Injury (SCI) • Energy requirement for SCI = H/B x 1.1 x 1.2 (Barco et al, NCP 17;309-313, 2002) • Pt with multi-traumas in addition to SCI may have higher needs • Protein needs: 2 g/kg (Rodriguez DJ et al, JPEN 15:319-322, 1991

35. Nutrition Support in Surgery/Trauma Graphic source www.nlm.nih.gov/.../ gallery/image/surgery.gif

36. Postoperative Nutrition Support • Introduction of solid foods depends on condition of GI • Oral feeding may be delayed for first 24 – 48 hours post surgery until return of bowel sounds, passage of flatus or soft abdomen • Traditional practice has been to progress from clear liquids, to full liquids, to solid foods • However, there is no physiological reason not to initiate solid foods once small amounts of liquids are tolerated

37. Energy Requirements in Surgery or Trauma • Will vary with type of surgery, degree of trauma • Use Ireton-Jones 1992 or Penn State if data is available* • Can use estimate of 25-30 kcals/kg to begin and monitor response to therapy** • Indirect calorimetry yields most accurate estimates, particularly in pts difficult to assess *ADA Evidence Analysis Library, accessed 10-06 **ASPEN Nutrition Support Practice Manual, 2nd Edition, p. 278

38. Hypocaloric Feedings • Hypocaloric feedings have been recommended in specific patient populations • Aggressive protein provision (1.5-2.0 gm/kg/day ASPEN Nutrition Support Practice Manual, 2nd Edition, p. 279 Zaloga GD. Permissive underfeeding. New Horizons 1994

39. Hypocaloric Feedings Have Been Recommended in: • Class III obesity (BMI>40 • Refeeding syndrome • Severe malnutrition • Trauma patients following shock resuscitation • Hemodynamic instability • Acute respiratory distress syndrome or COPD • MODS, SIRS or sepsis

40. Protein or Nitrogen Requirements in Surgery • 1.2 to 1.5 g protein/kg BW for anabolism mild or moderate stress • Nitrogen requirement estimated from energy requirements