Rachel Garvin, MD October 24, 2014 Nutrition in the ICU Rachel Garvin, MD October 24, 2014

How Much do I need? 56 yo F admitted to the ICU after a MVC h/o DM, HTN, HLD, OA She suffered a TBI, multiple rib fractures, PTX, tib-fib fx, splenic lac Intubated on MV HD#3 develops fevers to 103 BMI is 45

Goals of Presentation Why is nutrition important Calculating nutritional needs Enteral vs Parenteral Gastric vs Post-pyloric Formulas Residuals Probiotics

Energy Use Initially when body not getting enough total nutrients  fat used more the protein Glucose stores used up (small amounts of glucose needed for fat metabolism) Amino acids then needed for gluconeogenesis so lean body mass then lost This becomes problematic in patients who are nutritionally deplete prior to hospitalization

Revved up systems In critically ill patients, body moves into a hypercatabolic state Stress response In recovery, patients move into a hyperanabolic state Need substrate to build back up

Hypermetabolism Metabolic rate increases 120-250% in brain injured patients (even when sedated) SIRS-type response causing catecholamine surge; catabolic hormones surge Increased needs for: Protein Lipids Carbs Catabolic hormones: cortisol, glucagon,

Hypermetabolic State Increased Stress  Increased Catecholamines  increases lipolysis and gluconeogenesis Increased Stress  Increased Cortisol  Increased lipolysis and proteolysis

Hyperglycemia

What is Malnutrition Altered intake of macro and micronutrients Can lead to: Organ dysfunction Biochemical abnormalities Body mass index loss as lean body mass is catabolized Immune dysfunction

How do we measure nutritional status? Ideal body weight BMI Measure of body fat based on weight, height Plasma proteins: need to compare with positive APR Albumin – ½ life 2 weeks Prealbumin – ½ life 2 days Retinol binding protein – ½ life 12 hrs Transferrin

Nutritionally High Risk Increasing disease severity Pre-existing nutritional status Low BMI or recent weight loss Prolonged LOS

How do we know what our patient’s need? First – calculate total fluid requirement 20-40ml/kg day Second – total energy requirement Most straightforward: 25-30kcal/kg/day Metabolic cart Harris-Benedict Equation = REE (overestimates) Brain requires 20% of REE Clifton Equation 152-[14 x GCS] = 0.4 x HR + 7 x day since injury Fluid requirements increase: 12% with each degree of fever, 25% for sweating, 60% for hyperventilation The lower the GCS, the more kcal/day your patient needs: 30kcal/day for mild TBI up to 45kcal/day for severe TBI Metabolic Cart (indirect calorimtery) measures REE through Vo2 and CO2 prodction. Each liter of O2 consumed is equivalent to 5 kcal

Harris-Benedict Equation REE = basal metabolic rate REE x CF Women: REE = 655 + (9.6 X weight in kg) + (1.7 X height in cm) - (4.7 X age in years) Men: REE = 66 + (13.7 X weight in kg) + (5.0 X height in cm) - (6.8 X age in years) Calorie requirements/day = CF X REE (for each 1°C above 37 add 10% extra allowance Correction factors: Post-op: 1.1-1.5 Sepsis: 1.3 Multi-trauma: 1.5-1.6 Burns: 1.5-2

Metabolic Cart Measures VO2 (consumption) and VCO2 over 10-30 minutes For accuracy, need intubated patient at low FiO2 who is calm Can’t have any air leaks Dialysis can affect Shown to be most helpful in those at extremes of BMI

Special Situations Sepsis Significant catabolic state Higher protein requirement Respiratory Failure RQ (CO2 production/O2 consumption) Renal Failure Liver Failure Extremes of BMI (<20 or >40) Glucose metabolism R/Q 1.0 (above normal of 0.85) – overfeeding can be problematic with respiratory distress  increase CO2 production

Obese Patients Often fed later and inappropriately Increase protein (2-2.5g/kg/IBW) Decrease total requirement (65-70% of caloric requirement) Based on small RCTs ad retrospective cohort studies

Nitrogen Balance Urinary nitrogen balance Each gram of nitrogen produced requires 100-150kcal Patients with severe TBI who are not fed can lose up to 25g nitrogen/day Result is loss of up to 10% lean body mass in 1 week

Where are nutrients absorbed? Most nutrients are absorbed in the small intestines Water is absorbed in the stomach and colon Vit K, Na+, Cl-, K+ and short chain FA’s are absorbed in colon

Basics Carbs 30-70% Provides 4kcal/g Fat 20-50% Provides 9kcal/g Protein 15-20%

Enteral Nutrition

Data Behind EN EN within first 24-48 hours reduce infection, LOS and mortality Delay of EN or interruption of feeding produce significant calorie deficit Nurse driven protocols show earlier initiation of nutrition and decreased mortality Nurse driven protocols based on prospective data

Enteral vs Parenteral Enteral is preferred route Preserves GI barrier Maintains integrity of intestinal villi Reduces gut bacterial translocation Increased uptake of glutamine despite decreased intake Glutamine is most abundant AA in blood (precursor for purines/pyrimidines) and enterocytes use it as primary fuel source

Gastric vs. Post-pyloric Gastric feeds (especially bolus) simulate normal intake Gastric feeding allows body to regulate transition of food to duodenum and insulin release Gastric feeding allows better regulation of gastric pH Gastric is preferred unless: Patient unable to sit >30 degrees Ileus Residuals >500 Post-pyloric Need slower titration of rates to prevent dumping syndrome Decreased risk of aspiration with post-pyloric feeding but does not translate into lower rate of PNA, longth on MV, ICU LOS or mortality

Trophic vs Full Feeds? Study of ARDS pts showed no difference in oucomes in trophic (25% of calories) vs full feeds Trophic feeds for up to 6 days does not show harm (select patient populations) No surgical patients, most patients with BMI> 30 and excluded malnourished pts.

Feeding algorithm based on CHEST 2014 guidelines

Choosing an Enteral Formula Formulas with arginine, fish oil and nucleotides are helpful in elective surgery pts Anti-inflammatory lipids and omega-3s helpful in ARDS

TPN Consider parenteral nutrition if patient unable to tolerate enteral feeds by day 7 Need dedicated line Dextrose is major source of calories Lipids provide essential FA’s Max administration of 5-7g/kg/day Amino Acids Additives Electrolytes Vitamins Trace elements Insulin

TPN Calculators

Tube Feed Formulas Fibersource HN: standard high protein with fiber. 1.2kcal/ml Replete: 1.0kcal/ml. Higher protein than fibersource Impact peptide: 1.5kcal/ml. Concentrated calories Renal Formulas: 2.0kcal/ml, lower levels of K+ and phos Oxepa: low carb, high protein Peptamen: monomeric, predigested formula

Fluid Requirement 20-40ml/kg or 1ml/kcal Most tube feed formulas are 70- 80% free water Example: 70kg patient with large amount of insensible losses 40ml/kg x 70kg = 2800ml fluid requirement Getting tube feeds at 70ml/hr = 1680ml/day of which 1344 is free H2O

Probiotics Competitive inhibition of pathogens Stimulate physical gut barrier and mucous production Reduce adherence and attachment of pathogens Produce proteins that bind pathogens Stimulate T-cell production and increased secretory IgA Pathogens: pseudomonas, staph, enteroinvasive e.coli Works in the colon not SI

What about Glutamine Used for hepatic urea synthesis Renal ammoniagenesis Gluconeogenesis Respiratory fuel for cells Precursor for glutamate, excitatory neurotransmitter  increased seizure risk Also produces glutathione, a potent anti-oxidant Thought to be an essential additive but later study showed risk of increased mortality

Feeding on Pressors Prospective study 1174 medical pts requiring MV >2 days and pressor support (amt not noted). Early (within 48 hours) vs late EN. Both ICU and hospital mortality reduced even when adjustments made for confounding.

Residuals Slowed gastric motility – up to 50% of mechanically ventilated patients Stopping feeds based on GRV?

Gastric Residuals Compare effects of increasing GRV from 200500ml Randomized 329 patients GRV measured every 8 hours on EN day #2 and then daily Reglan given to all pts during first 3 days of EN Study by Montejo et al ICM 2010 Reglan dose 10mg q8 hours

Gastric Residuals Gastrointestinal complications: Abdominal distention High GRV: 200 vs 500ml Vomiting Diarrhea Aspiration

Gastric Residuals Incidence of complications higher in the control group Diet volume ratio similar in both groups (diet received/diet prescribed)

Summary Nutrition is vitally important in ICU patients Understand the nutritional needs of your patients Calculate requirement and/or get a nutrition consult Use the gut whenever possible Nutrition should commence by day 3 and not later than day 7