Nutrition Support of the Critically Ill Patient with Organ Failure

1. Nutrition Support of the Critically Ill Patient with Organ Failure

2. Respiratory Failure • Function of lungs: Move oxygen from air to venous blood and move carbon dioxide (CO2) out • Important functional components of lung: • Drive mechanism • Muscles of respiration • Alveoli Source: Hasse J. Nutrition and Organ Failure. In DNS. Sharpening Your Skills as a Nutrition Support Dietitian, 2003, p. 227

3. Acute Respiratory Failure • Type 1: hypoxic respiratory failure. • Low PaO2 with low to normal PaCO2 • (PaO2/PaCO2 = partial pressure exerted by O2/CO2 dissolved in arterial plasma) • Type 2: hypercapneic-hypoxic respiratory failure. • Low PaO2 with increased PaCO2

4. Acute Respiratory Distress Syndrome (ARDS) • PaO2:FiO2 ratio ≤ 200 • (FiO2 = fraction of inspired oxygen, the % concentration of oxygen entering the lungs, ventilator or a blood oxygenator) • Bilateral pulmonary infiltrates seen on X-ray • PAW ≤ 15) mm/Hg • PAW = pulmonary artery wedge pressure; normal is ≤ 12 mm/Hg

5. Chronic Respiratory Failure • Asthma • COPD • Bronchiectasis • Cystic Fibrosis • Infiltrative disease of the lung • Pulmonary hypertension

6. Treatment Goals for Respiratory Failure • Treat underlying condition • Support physiologic function • Maintain tissue oxygen delivery • Minimize pulmonary edema • Give nutrition support • Prevent/manage infection Source: Hasse J. Nutrition and Organ Failure. In DNS. Sharpening Your Skills as a Nutrition Support Dietitian, 2003, p. 227

7. Mechanical Ventilation Modes • Assist control (AC) • Intermittent mandatory ventilation • Synchronized intermittent mandatory ventilation

8. Mechanical Ventilation Settings • CPAP: continuous positive airway pressure • PEEP: positive end-expiratory pressure • PEEP: A method of ventilation in which airway pressure is maintained above atmospheric pressure at the end of exhalation by means of a mechanical impedance, usually a valve, within the circuit. Purpose is to increase volume of gas remaining in lungs after expiration to decrease shunting of blood through the lungs and improve gas exchange. PEEP is done in ARDS (acute respiratory failure syndrome) to allow reduction in the level of oxygen being given • PSV: pressure support ventilation • HFV: high frequency ventilation

9. Nutrient Requirements in Pulmonary Failure • Calories: don’t overfeed when weaning to prevent increased CO2 production • Provide 25-30 kcal/kg or resting energy expenditure • Protein: 1.5-2 g/kg • Amino acids may increase ventilation, increase O2 consumption and ventilatory response to hypoxia and hypercapnea • Carbohydrate: <5 ,g/kg/min • Overall calories more important than percent CHO • Fat: N3 FA may be anti-inflammatory and alter immune status in sepsis/ARDS

10. Respiratory Quotient (RQ) • RQ is the ratio of carbon dioxide produced to oxygen consumed; is an indicator of fuel utilization • Normal (physiologic) range is 0.5 to 1.5 • High RQ in a ventilator patient may make it difficult to wean the patient from the respirator

11. Respiratory Quotient Values for Various Fuel Substrates

12. Treatment Goals for Liver Failure • Identify and treat cause of liver failure (if reversible) • Control problems associated with liver failure • Give nutrition support • Prevent/treat infection

13. Nutrient Requirements for Liver Failure • Calories: caloric requirements affected by acuteness of disease, seriousness of injury, absorption, other organ failure, sepsis; 25-35 kcals/kg or REE • Protein: well nourished/low stress: .8 g/kg; malnourished/with metabolic stress: up to 1.5 g/kg • CHO: ~70% non-protein calories; in acute failure, may need continuous glucose infusion • Chronic: may have diabetes/hypoglycemia requiring controlled CHO and insulin; in septic pts hypoglycemia occurs in 50% of cirrhotics • FAT: 30% non-protein calories; MCT may be helpful with LCT malabsorption

14. Fat Soluble Vitamins: Causes of Deficiencies in Liver Failure • Vitamin A: steatorrhea, neomycin, cholestyramine, alcohol • Vitamin D: steatorrhea, glucocorticoids, cholestyramine • Vitamin E: steaorrhea, cholestyramine • Vitamin K: steatorrhea, antibiotics, cholestyramine Source: Hasse J. Nutrition and Organ Failure. In DNS. Sharpening Your Skills as a Nutrition Support Dietitian, 2003, p. 227

15. Water Soluble Vitamins: Causes of Deficiencies in Liver Failure • B6: alcoholism • B12: cannot exclude deficiency during active liver inflammation, fatty liver, carcinoma; causes alcoholism, cholestyramine • Niacin: alcoholism • Thiamin: alcoholism • Folate:alcoholism Source: Hasse J. Nutrition and Organ Failure. In DNS. Sharpening Your Skills as a Nutrition Support Dietitian, 2003, p. 227

16. Minerals: Causes of Deficiencies in Liver Failure • Zinc: diarrhea, diuretics, alcoholism • Magnesium: alcoholism, diuretics • Iron: chronic bleeding (hemochromatosis causes overload) • Potassium: affected by diuretics, anabolism, insulin use, renal function • Phosphorus: affected by alcoholism, anabolism, renal function

17. Renal Failure: Functions of Kidney • Excrete waste • Electrolyte balance • Hormonal regulation • Blood pressure regulation • Glucose homeostatis

18. Causes of Acute Renal Failure • Acute Tubular Necrosis: nephrotoxins (radiologic contrasts) aminoglycosides, NSAIDS, cisplatin, ethylene glycol, ACE inhibitors. Presents with ↓ UO, ↑ BUN, ↑ Creatinine, ↓ HCO3, ↑ or normal K+, ↑ phos • Oliguric phase persists ~1-2 weeks followed by diuretic phase

19. Causes of Acute Renal Failure • Prerenal azotemia: most common cause of acute azotemia, secondary to volume depletion • Acute interstitial nephritis • Atheromatous emboli • Ureteral obstruction • Intrarenal obstruction

20. Treatment Goals for Acute Renal Failure • Correct electrolytes • Control acidosis • Treat significant hyperphosphatemia • Treat symptomatic anemia • Initiate dialysis for hyperkalemia or acidosis not controlled, fluid overload, ↑ in BUN>20 mg/dl/24 hours or BUN>100 mg/dl • Evaluate drugs for renal effect • Avoid/treat infection

21. Continuous Renal Replacement Therapy (CRRT) • Blood filtered continuously by semi-permeable membrane • Arteriovenous uses patient’s own blood pressure • Venovenous: pump-driven • Lower extracorporeal blood volume (compared to HD) so better tolerated by hemodynamically unstable patients • Types: hemofiltration (AVH, CAVH, SCUF), continuous hemodialysis (CAVHD, CVVHD) and continuous hemodiafiltration (CAVHDF or CVVHDF)

22. Nutrition Implications of ARF • ARF causes anorexia, nausea, vomiting, bleeding • ARF causes rapid nitrogen loss and lean body mass loss (hypercatabolism) • ARF causes ↑ gluconeogenesis with insulin resistance • Dialysis causes loss of amino acids and protein • Uremia toxins cause impaired glucose utilization and protein synthesis

23. Nutrient Requirements in ARF • Calories: 25-45 kcals/kg dry weight or REE • Protein: about 10-16 g amino acids lost per day with CRRT • ARF w/o HD (expected to resolve within a few days): .6-1 g pro/kg • Acute HD: 1.2-1.4 g/kg; acute PD: 1.2-1.5 g/kg; CRRT: 1.5-2.5 g/kg • CHO: ~60% total calories; limit to 5 mg/kg/min; peripheral insulin resistance may limit CHO • In CWHD(F) watch for CHO in dialysate or replacement fluids • Fat: 20-35% of total calories; lipid clearance may be impaired

24. Vitamins in ARF • Vitamin A: elevated vitamin A levels are known to occur with RF • Vitamin B – prevent B6 deficiency by giving 10 mg pyridoxine hydrochloride/day • Folate and B6: supplement when homocysteine levels are high • Vitamin C: <200 mg/day to prevent ↑ oxalate • Activated vitamin D • Vitamin K: give Vitamin K especially to pts on antibiotics that suppress gut production of K

25. Minerals in RF • ↑ potassium, magnesium, and phos occur often due to ↓ renal clearance and ↑ protein catabolism • ↓ potassium, mg and phos can occur with refeeding • CRRT pts can have ↓ K+, phos • Mg deficiency can cause K+ deficiency resistant to supplementation • Vitamin C, copper, chromium lost with CVVH

26. Fluid in ARF • Depends on residual renal function, fluid and sodium status, other losses • Usually 500 mL/day + urine output • Fluid replacement needs can be ↑ with CRRT

27. Multiple Organ Failure: 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

28. Nutrition/Metabolism Considerations • Determine priorities for medical and nutrition therapy • 3-5 times higher catabolism • Increased skeletal muscle proteolysis • Shift of amino acids from periphery to viscera for gluconeogenesis

29. Nutrient Needs in MODS • Calories: 35 kcal/kg or REE • Protein: up to 1.5-2.0 g/kg • Fat: 30% nonprotein calories; ↑ MCT if bile salt deficient; N3 vs N6 • Micronutrients: evaluate individually • Fluid: based on fluid status Source: Hasse J. Nutrition and Organ Failure. In DNS. Sharpening Your Skills as a Nutrition Support Dietitian, 2003

30. Feeding Route • EN usually preferred over PN; PN may worsen liver function • Intubation does not preclude aspiration • EN not contraindicated with varices • Patients with CRF often may have gastroparesis; may need motility agent Source: Hasse J. Nutrition and Organ Failure. In DNS. Sharpening Your Skills as a Nutrition Support Dietitian, 2003

31. Formula Selection • Concentrated formulas may be helpful with fluid restriction • Formulas restricted in phos and potassium may be helpful in pts with high phos and K+ • Immune-enhancing formulas (controversial) Source: Hasse J. Nutrition and Organ Failure. In DNS. Sharpening Your Skills as a Nutrition Support Dietitian, 2003

32. Conclusion • Critically ill patients with organ failure present special challenges to the nutrition care professional and medical team • Medical and nutritional goals must be prioritized in these complex patients