Nutrition Therapy of the Critically Ill Patient with

Organ FailureChris A Johannes

INASPEN

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

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

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

Chronic Respiratory Failure

Asthma COPD Bronchiectasis Cystic Fibrosis Infiltrative disease of the lung Pulmonary hypertension

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

Mechanical Ventilation Modes

Assist control (AC) Intermittent mandatory ventilation Synchronized intermittent mandatory

ventilation

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

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

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

Respiratory Quotient Values for Various Fuel Substrates

Fat 0.7

Protein 0.8

Carbohydrate 1.0

Mixed Diet ~0.85

Alcohol 0.67

Underfed <0.8

Adequately fed 0.8-1.0

Overfed >1.0

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

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

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

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

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

Renal Failure: Functions of Kidney

Excrete waste Electrolyte balance Hormonal regulation Blood pressure regulation Glucose homeostatis

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

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

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

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)

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

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

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

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

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

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

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

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

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

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

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