ADULT NUTRITION SUPPORT IN CRITICALLY ILL PATIENTS IN ICU PATIENTS

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Overview:

Nutrition assessment of the critically ill patients presents a unique challenge to the dietitian.

Traditional methods are of limited value in the intensive care setting.

No simple recommendation can be appropriate.

Reassessment should be completed periodically because of the prolonged stay of ICU patients.

A close monitoring of intake and response to nutrition therapy should be done daily.

Clinical implications: Nutrition requirements for critically ill patients depend on the severity of the disease or injury, as well as prior nutritional state. Adequate protein and calories should be provided to counteract protein catabolism and to reduce complications. OBJECTIVES OF NUTRITION SUPPORT IN THE CRITICALLY ILL POPULATION:

To preserve lean body mass.

To maintain immune function.

To avert metabolic complications.

To modulate the immune response.

To prevent oxidative cellular injury.

PATIENT AT RISK FOR MALNUTRITION:

Severely underweight (<80% IBW).

Severely overweight (>120% IBW).

Recent weight loss (>10% over 3months).

Being alcoholic/ substance dependent.

Nil per month (NPO) > 5days.

Increased nutrient losses: o Malabsorption. o Short bowel syndrome. o Fistula. o Draining abscesses or wound/ burns. o Renal dialysis.

Increase nutrient requirement: o Trauma. o Burns. o Sepsis.

MALNUTRITION IS ASSOCIATED WITH:

Increase Length of Stay (LOS) thus hospital cost increase.

Higher complication rates (e.g. wound infections and pneumonia).

Higher mortality rates.

Increase weight loss, which increase with LOS. NUTRITION SCREENING: Malnourished patients. Patients at risk of becoming malnourished. Patients who need nutritional assessment. Conducted within 24hours of admission to hospital. Accurate to identify nutritional risk, yet simple enough to be completed in 5-15minutes. Conducted by registered dietician or dietetic technician varies among health care settings.

PRINCIPLES OF NUTRITION ASSESSMENT:

Medical Status.

Social Status.

Nutritional status: o Dietary & food intake o Clinical assessment o Biochemistry:

• Protein status. • Nutritional anemia. • Laboratory data. • Blood gasses.

Anthropometry.

NUTRITION SCREENING 

NUTRITION ASSESSMENT

NUTRITION DIAGNOSIS 

NUTRITION INTERVENTION

NUTRITION MONITORING & EVALUATION 

NUTRITION ASSESSMENT: MEDICAL STATUS: Current diagnosis. Organ function (heart, liver, kidney, brain, GI, lungs). Underlying diseases (e.g. DM, HTN, HIV). Previous operations. Medical management (e.g. CVVHD, level of sedation, medication, IV fluids, stability/

inotropes, sepsis/ infection and hydration status). NUTRITION ASSESSMENT: SOCIAL STATUS: Socioeconomic status. Cultural/ ethnic identity. Educational level. Living situation. Shopping arrangements. Cooking facilities.

NUTRITION ASSESSMENT: NUTRITIONAL STATUS DIETARY AND FLUID INTAKE: Dietary patterns. Dietary restriction. Use of alcohol. Food allergies and intolerance. Chewing and swallowing ability. Need for feeding assistance. Current & past dietary make if possible.

o When was the last meal taken? o Known allergies.

On Special diet? Oral or enteral feeding. Texture of food/ fluids. IV (nutrient supplied by IV fluids). Propofol-fat. Maintenance- glucose. Nutrients supplied by dialysis fluids. Medication (Nutrient-medication interaction). Blood and blood products. Appetite, nausea, vomiting. Constipation, diarrhea. Pain, fatigue, depression. Religion. Preferences, like/ dislikes. Low levels of vitamin A, Zinc, Magnesium are common in Malnutrition. Evaluation of Anemia, Vitamin B12 & Folate levels is common in Malnutrition. Fat- soluble vitamin (A, D, E and K) and mineral (iron & folic acid) deficiency common in

digestion & absorption disorders.

NUTRITION ASSESSMENT: NUTRITIONAL STATUS CLINICAL ASSESSMENT:

GRV RECOMMENDATION >500ml Withhold feeds and reassess the patient's

tolerance. 200-500ml Maintain feeding

Careful bedside evaluation. <200ml Maintain feeding.

NUTRITION ASSESSMENT: NUTRITIONAL STATUS BIOCHEMISTRY-PROTEIN STATUS:

ALBUMIN

Low levels suggest protein energy malnutrition.

Not reliable in acute clinical conditions: ‐ Has long half-life (15-20 days). ‐ 60% albumin is in extravascular

space & shifts to intravascular space during decreased protein intake.

‐ Affected by hydration status. Normal Serum Level 3.5 – 5.5mg/dL

TRANSFERRIN

Transports iron and also responsive to dietary protein intake.

Low levels are indicative of protein energy malnutrition.

Hepatic & renal disease, inflammatory process will decrease serum levels.

Reflects acute nutrition changes: ‐ Half-life 8 days. ‐ Iron stores control transferrin levels.

(Low iron stores… serum transferring synthesis increases).

Normal Serum Level 250 – 300mg/dL

PREALBUMIN (TRANSTHYRETIN)

Transport protein that binds retinal-binding protein (RBP) and thyroxin.

Low levels suggest protein energy malnutrition.

Useful in monitoring acute nutritional status changes in critically ill: ‐ Half-life 2 to 3 days. ‐ Adequate nutrition should increase

prealbumin within 4 to 8 days. ‐ Transiently decrease during

inflammation & post surgery. Low serum zinc may impair hepatic

prealbumin synthesis. Normal Serum Level 15 – 32mg/dL

NUTRITION ASSESSMENT: NUTRITIONAL STATUS BIOCHEMISTRY-PROTEIN STATUS- SUMMARY:

FACTOR ALBUMIN TRANSFERRIN RBP PRE-ALBUMIN

Fluid disturbances √ √ √ √ Therapeutic administration √ Loss due to vascular permeability √ APR √ Negative acute phase protein √ √ √ √ Half life 18-20d 8d 12h 2d Iron pool √ Zinc deficiency √ √ Vitamin A deficiency Renal failure/ nephrotic syndrome √ √ √ √ Liver disease √ √ √ √ RBP- Retinol Binding Protein NUTRITION ASSESSMENT: NUTRITIONAL STATUS BIOCHEMISTRY-LABORATORY DATA:

PHYSIOLOGICAL FLUID COMMENTS Serum Calcium Correct for low albumin. Magnesium Correct for low albumin. Phosphate Re-feeding syndrome. Urea, creatinine and electrolytes Presence of renal failure. Liver function (LFTs) Presence of the liver failure, PN induced. Glucose Glucose intolerance. Osmolarity Inappropriate ADH secretion. Sodium Inappropriate ADH secretion. Creatinine Renal impairment. Protein Proteinuria. Glucose Glycosuria. NUTRITION ASSESSMENT: NUTRITIONAL STATUS BIOCHEMISTRY-BLOOD GASSES:

SHOULD BE ASSESSED DAILY Calcium Correct for low albumin Low PO2 count. Contraindication for nutrition support. High PCO2 count (unrelated to pulmonary dysfunction or ventilation settings).

May necessitate an alteration of CHO & Fat distribution during weaning.

NUTRITION ASSESSMENT: NUTRITIONAL STATUS BIOCHEMISTRY-IMMUNE FUNCTION:

Poor nutrition can be major contributor to immune-suppression by: o Depressing neutrophil chemotaxis. o Total lymphocyte count (TLC). o Delayed hypersensitivity reactivity (DHR).

TLC= % Lymphocytes X WBC 100

Total Lymphocyte Count <1500 mm3 is indicative of impaired immune function. NUTRITION ASSESSMENT: NUTRITIONAL STATUS ANTHROPOMETRY: Body weight:

o Risk for malnutrition: • Weight loss > 10% UBW in 3 months. • Body weight < 90% IBW.

o Malnutrition: • Body weight <85% IBW.

o Severe malnutrition: • Body weight <70% IBW.

o Body weight: • Is affected by fluid shift (intracellular to extracellular and

intravascular to extravascular) and accumulated caused by inflammation.

• May fluctuate ~10-15L fluid retention during aggressive fluid resuscitation.

• Must be adjusted to account for amputation: Estimated Ideal Weight =[(100% of amputation)/ 100] x IBW for original height.

o Body height:

• Bed length. • Knee height. • Arm span.

GOALS OF NUTRITION MANAGEMENT: Detect and correct preexisting malnutrition. Prevent progressive protein-calorie malnutrition. Optimize patient's metabolic state by managing fluid and electrolytes.

DETERMINATION OF REQUIREMENTS: Energy. Protein. Vitamins, Minerals, Trace Elements. Non-protein, substrate:

o Carbohydrate. o Fat.

ENERGY REQUIREMENTS: Enough but not too much. Effects of excess calories:

o Dieresis – complicates fluid/ electrolyte balance.

o Hepatic steatosis (fatty liver). o Excess CO2 production:

• Exacerbate respiratory insufficiency. • Prolong weaning from mechanical ventilation.

ASPEN GUIDELINES Energy Requirements in Critical Care: Indirect Calorimetry is the standard for determination of RMR in critically ill patients since

RMR based on measurement is more accurate than estimation using predictive equations. When indirect calorimetry cannot be performed, predictive formulas may be necessary.

INDIRECT CALORIMETRY: 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). Expensive to perform routinely.

RESPIRATORY QUOTIENT: Respiratory Quotient (RQ) is the ratio of VCO2 and VO2 and is function of the mix of

substrates being utilized for metabolism. An RQ of <0.7 or >1.0 may identify unusual metabolic or respiratory conditions, failures to

adhere to the fasting requirement of the measurement protocol, and/ or operator or equipment error.

A repeated measurement should ne considered if an RQ value is outside the range of 0.7 to 1.0.

INDICATIONS FOR INDIRECT CALORIMETRY: Patients with altered body composition (underweight, obese, limb amputation, peripheral

edema, ascites). Difficult weaning from mechanical ventilation. Patients s/p organ transplant. Patients with sepsis or hyper-catabolic states (Pancreatitis, trauma, burns, ARDS). Failure to respond to standard nutrition support.

GUIDELINES

Determining RMR in Critical Illness, Mechanically Ventilated, Obese Ireton-Jones, 1992. Penn State, 2003. 11-14 kcal/kg Actual Body Weight (BMI ≥ 40). 22-25 kcal/kg Ideal Body Weight (BMI 30-40).

Best prediction accuracy of equations studied. In some individuals errors between predicted and actual energy needs will result in under- or over-feeding.

USE OF HYPO-CALORIC FEEDINGS: Class III obesity (BMI>40). Re-feeding syndrome. Severe malnutrition. Trauma patients following shock resuscitation. Hemodynamic instability. Acute respiratory distress syndrome or COPD. SIRS or sepsis.

Carbohydrate Requirements: Should provide ~60-70% of total calories. Provide at a rate of 4mg/kg/min. 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 between 110-150 mg/dl. Fat Requirements: Should provide ~10-30% of total calories. 0.5-2.0 g/kg/day or possibly 1.0 g/kg/day IV. Caution with use of fats in stressed & trauma patients:

o There is evidence that high fat feedings (especially LCT) cause immnosuppression. o New formulas focus on Omega 3 Fatty Acids.

Intolerance sings: o Hyperlipidemia. o Impaired Immune Function. o Hypoxemia.

Protein Requirements: General Recommendation: 1.5-2.0 g/kg/day. Non-protein calorie/ gram of nitrogen ratio for critically ill = 100:1 For Patients receiving:

o CRRT: (1.5- 2.5 g/kg/day) (to promote +N balance). o Hemodialysis: (1.2g/kg/day). o Renal Failure, Not dialyzed: (0.8 - 1 g/kg/day).

For Obese: o ≥ 2.0 g/kg IBW (BMI 30-40). o ≥ 2.5 g/kg IBW (BMI ≥ 40).

Fluid and Electrolytes Requirements: Fluid (common formulas):

o 1ml of water per kcal. o 35 ml/kg (20-55y old). o 30 ml/kg (55-75y old). o 25 ml/kg (>75y old). o 1500 ml for 1st 20kg of body weight+20ml/kg of each kg over 20kg.

Electrolytes/ Vitamins/ Trace Elements:

o Enteral feedings: begin with RDA/ AI values. o PN: use PN dosing guidelines.

Conclusion:

Nutritional goals for critically ill patients should focused on: o The protein, calories and micronutrients needs. o The potential response of patients to different nutrients. o The composition of specialized formulas.

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