Nutritional Requirements and Enteral Support of the Critically Ill, Ventilated Patient

1. Nutritional Requirements and Enteral Support of the Critically Ill, Ventilated Patient John P. Grant, MD, CNSP Director Nutrition Support Service Professor of Surgery Duke University Medical Center Durham, NC

2. Nutritional Requirements and Enteral Support of the Critically Ill, Ventilated Patient Slides available at: http://tpnteam.com

3. Optimal Metabolic Care of the Critically Ill, Ventilated Patient • Optimize milieu for cell metabolism • Minimize stress response • Provide adequate and appropriate nutritional support

4. Optimal Metabolic Care of the Critically Ill, Ventilated Patient • Provide Optimal Metabolic Milieu • Establish and maintain oxygenation • Adjust pH • Ensure adequate tissue perfusion • Control waste (dialysis)

5. Optimal Metabolic Care of the Critically Ill, Ventilated Patient • Provide Optimal Metabolic Milieu • Minimize Metabolic Stress Response • Control pain • Debridement of necrotic/infected tissue • Drain abscesses • Dress or cover wounds

6. Optimal Metabolic Care of the Critically Ill, Ventilated Patient • Optimize milieu for cell metabolism • Minimize stress response • Provide adequate and appropriate nutritional support

7. Importance of Adequate Nutrition • Nutrient balance and mortality in ICU patients • 4/15 with positive caloric balance died (27%) • 11/28 with 0 to -10,000 kcal balance died (39%) • 12/14 with > -10,000 kcal balance died (86%) Bartlett et al., Surgery 92:771, 1982

8. Caloric Balance and Outcome in ICU A = positive caloric balance B = 0 to -10,000 kcal balance C = > -10,000 kcal balance Caloric Balance vs % Mortality 86% 90 80 70 60 50 39% 40 27% 30 20 10 0 A B C Bartlett et al., Surgery 92:771, 1982

9. Days of Survival Without Nutrition Days = { [(UBW X 2430) x K] - [(UBW - BW) x 2430]} AEE - Ei Where: UBW = usual body weight in kgBW = current body weight in kg K = 0.35 with stress; 0.40 with simple starvation AEE = actual energy expenditure (kcal/d)Ei = energy intake (kcal/d)

10. Importance of Adequate Nutritionin Respirator Dependent Patients • Arora and Rochester evaluated the effects of malnutrition on diaphragmatic muscle dimensions at necropsy and in vivo function in patients after prolonged illness (75% UBW) as compared with well nourished patients Arora and Rochester: Am. Rev. Respir. Dis., 126:5-8, 1982.

11. Impact of Malnutrition on Pulmonary Function • Sahebjami and Wirman studied the lungs of adult rats subjected to 3 weeks of semi-starvation (approximately 40 percent loss of total body weight). They found: • Marked emphysematous changes • An increase in size of air spaces and reduction in alveolar wall surface tension • Elastic fibers were shortened, irregular, and fewer in number Sahebjami and Wirman: Am. Rev. Respir. Dis., 124:619-624, 1981.

12. Impact of Malnutrition on Pulmonary Function • Reticular fibers were unchanged • Biochemical measurements demonstrated a reduction in desaturated lecithin. Because lecithin is a major component of surfactant, it was proposed that alveolar collapse with emphysematous changes might be expected • Refeeding the rats corrected desaturated lecithin concentrations but failed to reverse the morphological emphysematous changes Sahebjami and Wirman: Am. Rev. Respir. Dis., 124:619-624, 1981.

13. Impact of Malnutrition on Pulmonary Function Doekel et al. placed volunteers on a balanced 550 kcal/day diet for 10 days and demonstrated a 20% reduction in basal oxygen consumption and a 58% reduction in their ventilatory response to hypercapnea. (N. Engl. J. Med., 295:358-361, 1976) Askanazi et al. fed volunteers a hypocaloric (550 Kcal/day), balanced diet for 10 days and demonstrated a 58% reduction in ventilatory response to hypoxia. (Anesthesiol. 53(Supp 1):185, 1980) Refeeding in both studies restored normal function

14. Impact of Malnutrition on Pulmonary Function • Minnesota Experiment: Routine pulmonary function tests were performed before and after 24 weeks of semi-starvation • Vital capacity, tidal volume, and minute ventilation decreased by 7, 19, and 31 percent, respectively • Refeeding resulted in improvement but incomplete recovery, even after 12 weeks Keys et al.: The Biology of Human Starvation. Minneapolis, University of Minnesota Press, 1950.

15. Impact of Malnutrition on Pulmonary Function Duke data, unpublished: Recovery of Organ Function With 2 Weeks of TPN in 21 Malnourished, Non-stressed Patients

16. Impact of Malnutrition on Pulmonary Function

17. Impact of Malnutrition on Pulmonary Function Bassili and Deitel, and Mattar et al. evaluated the effects of inadequate nutritional support on the ability to wean patients from mechanical ventilation. Combining their results: 22 of 25 patients (88%) who received adequate nutritional support could be weaned from the respirator, whereas only 10 of 31 patients (32%) who did not receive adequate support were able to be weaned (p < .001) Bassili and Deitel: J.P.E.N. J. Parenter. Enteral Nutr., 5:161-163, 1981. Mattar et al.: J.P.E.N. J. Parenter. Enteral Nutr., 2:50, 1978.

18. Adequate Nutritional Support of Critically Ill, Ventilated Patients • Protein Support – normal - Adjust for co-existing illnesses and to achieve positive nitrogen balance, reduce for renal and hepatic dysfunction - What to Give -

19. Adequate Nutritional Support of Critically Ill, Ventilated Patients • Caloric Support – Ireton-Jones formula Recently re-designed, specifically for ventilator-dependent patients in the ICU: • BEE = 1784 - 11(A) + 5(W) + 244(S) 239(T) + 804(B) • Where: A = age in years, W = weight in kilograms,S = sex (male = 1, female = 0), and T = trauma and B = burn (present = 1, absent = 0) Ireton-Jones, C., NCP, 17:29-31, 2002

20. Adequate Nutritional Support of Critically Ill, Ventilated Patients • Caloric Support – Cal Long Modification of H-B AEE (men) = (66.47 + 13.75 W + 5.0 H - 6.76 A) x (activity factor) x (injury factor) AEE (women) = (655.10 + 9.56 W + 1.85 H - 4.68 A) x (activity factor) x (injury factor)

21. Adequate Nutritional Support of Critically Ill, Ventilated Patients • Caloric Support – Swinamer formula Specifically for critically ill ventilated patients in the ICU: • REE = BSA(941) + Tmax(104) + RR(24) +Vt(804) - 4243 • Where: BSA = body surface area, T = temperature, RR = respiratory rate, Vt = tidal volume Swinamer, D.L. et al. Crit. Care Med., 18:657-661, 1990

22. Adequate Nutritional Support of Critically Ill, Ventilated Patients • Excessive calories can result in excessive CO2 production, increased arterial pCO2, RQ > 1.0, and increased ventilatory demand in the already compromised ventilated patient. • May delay weaning • May render respiratory support difficult

23. Adequate Nutritional Support of Critically Ill, Ventilated Patients • In ventilatory dependent patients, a high caloric load (2 X REE) has been shown to result in significantly higher O2 consumption and CO2 production than a moderate load (1.5 X REE) in patients otherwise receiving an identical diet Van den Berg and Stam: Intensive Care Medicine, 14:206-211, 1988.

24. Adequate Nutritional Support of Critically Ill, Ventilated Patients • Clearly, total caloric intake has a greater impact on CO2 production and respiratory function than does the ratio of CHO/fat (varying CHO content from 40-75% of total calories has little impact) • Recommend 1.2 to 1.5 times REE (up to 5 mg/kg/min CHO infusion – 40 to 50% of total calories as CHO) Talpers et al: Chest, 102:551-555, 1992. Van den Berg and Stam: Intensive Care Medicine, 14:206-211, 1988.

25. Burke et al., Ann Surg, 190:274, 1979 As increasing amounts of glucose are infused, a maximal rate of glucose oxidation and whole body protein synthesis is obtained at 5.0 to 6.0 mg/kg/min (~630 g/d for 80 kg patient)

26. Use of Insulin to Stimulate Glucose Utilization • Does lower blood sugar in most cases • Drives glucose mainly into muscle • No documented increase in glucose oxidation or nitrogen sparing Vary et al., JPEN 10:351, 1986

27. Use of Insulin in Glucose Utilization Anaerobic Glycolysis Pyruvate Pyruvate Dehydrogenase Krebs cycle Fat Synthesis å Insulin

28. Optimal Metabolic Care of the Critically Ill, Ventilated Patient Benefits of Early Enteral Nutrition vs. Parenteral Nutrition

29. Early Enteral Nutrition • Initiation of enteral nutrition within 24 to 48 hours of hospitalization or catastrophic event • Initiation of nutrition support after 72 hours may have no appreciable effect on morbidity

30. Early Enteral Nutrition Reduces hypermetabolism in trauma, burn, and postoperative patients

31. Postburn Hypermetabolism and Early Enteral Feeding • 30% BSA burn in guinea pigs • Enteral feeding via g-tube at 2 or 72 hours following burn • Mucosal weight and thickness were similar RME % Initial 160 175 Kcal - 72 h 150 140 200 Kcal - 72 h 130 120 175 Kcal - 2 h 110 100 0 2 4 6 8 10 12 Postburn day Alexander, Ann. Surg., 200:297, 1984

32. Early Enteral Nutrition Maintains gut mucosal barrier • Bulk stimulation • Fuel source for enterocyte - glutamine • TPN without glutamine = Intestinal atrophy – bacterial translocation

33. Enterocytes Lymphocytes Fibroblasts Bone Marrow Pancreas Lung Tumor Cells Renal Tubular Cells Vascular Epithelial Cells Glutamine in Cellular NutritionMajor Fuel For:

34. Glutamine • Necessary precursor for protein and nucleotide synthesis • Regulates acid-base balance through production of urinary ammonia • Major transporter of nitrogen (along with alanine) • Oxidation via Krebs cycle yields 30 mole ATP per mole glutamine (glucose = 36)

35. Glutamine Metabolism • Gut normally extracts 20 to 30% of glutamine from blood • During stress, muscle releases amino acids with glutamine and alanine making up 60% of total • Muscle glutamine concentration decreases by up to 50% and serum concentrations fall with prolonged stress

36. Adequate Nutritional Support of Respirator Dependent Patients Content of Enteral Formulas

37. Early Enteral Nutrition Maintains GALT system

38. GALT System • Gut-associated lymphoid tissue • Intraepithelial lymphocytes • Lamina propria lymphoid tissue • Peyer’s patches • Mesenteric lymph nodes

39. GALT System • Intraepithelial lymphocytes • First to recognize foreign antigens • Lamina propria lymphoid tissue • Source of IgA • Peyer’s patches • Process antigens from intestinal lumen

40. GALT System • Responsible for reacting to harmful foreign antigens (e.g. bacterial or viral pathogens) • Must not react to non-threatening antigens to avoid chronic inflammatory condition

41. GALT System • Intravenous feeding with bowel rest and starvation result in significant suppression of the mass and function of GALT, with reduction in IgA secretion and increased gut permeability • Oral and enteral feedings preserve GALT mass and function Li, J Trauma, 39:44, 1995

42. GALT System • Bowel rest (or an elemental diet) reduces intraluminal nutrients that bacteria need • Induces an adaptive response of bacteria to increase their adherence to the intestinal wall as a source of nutrients • Bacterial adherence causes cellular injury, or even bacterial penetration (translocation), with an adverse host response

43. Early Enteral Nutrition • Better maintenance of endogenous antioxidant pools • Helps reverse and prevent stress-induced splanchnic ischemia

44. Nutritional Support of the Critically Ill, Ventilated Patient Problems with Enteral: Underfeeding • High gastric residuals • Fear of Aspiration • Constipation/Diarrhea • Abdominal distention • Nausea and vomiting

45. Nutritional Support of the Critically Ill, Ventilated Patient Problems with Enteral: Underfeeding • McClave et al. prospectively evaluated enteral tube feedings in 44 medical ICU/coronary care unit patients (mean age, 57.8 years) who received nothing by mouth and were placed on enteral tube feeding McClave et al.: Crit. Care Med., 27:1252-1256, 1999

46. Nutritional Support of the Critically Ill, Ventilated Patient • Physicians ordered a daily mean volume of enteral tube feeding that was only 65.6% of goal requirements • On average, only 78.1% of the volume ordered was actually infused • Thus, patients received a mean volume of enteral tube feeding that was only 51.6% of goal McClave et al.: Crit. Care Med., 27:1252-1256, 1999

47. Nutritional Support of Critically Ill, Ventilated Patient • Only 14% of patients reached or exceeded 90% of goal feedings (for a single day) within 72 hours of the start of enteral tube feeding • Of 24 patients weighed before and after, 54% were lost weight on enteral tube feeding • Declining albumin levels correlated significantly with decreasing percent of goal calories infused McClave et al.: Crit. Care Med., 27:1252-1256, 1999

48. Nutritional Support of Critically Ill, Ventilated Patient • NOTE: This may not be of major concern, perhaps it is actually beneficial – avoidance of overfeeding • Some contend that the problems with parenteral nutrition are due to overfeeding, since what is prescribed is more commonly given to the patient

49. Nutritional Support of the Critically Ill, Ventilated Patient Problems with Enteral: Aspiration • Most feel TF is associated with an increased incidence of pneumonia – not aspiration • Most common event is aspiration of saliva • Consider use of feeding tube distal to stomach: Nasojejunal, gastrojejunal, or jejunostomy

50. Fluoroscopic Placement Nasojejunal Tube Note: injection of Gastrografin to evaluate small bowel anatomy and motility. Note: injection of Gastrografin to evaluate small bowel anatomy and motility.