Transcript ICU Nutrition - UTHSCSA

Nutrition in the ICU
Rachel Garvin, MD
October 24, 2014
How Much do I need?
O 56 yo F admitted to the ICU after a MVC
O h/o DM, HTN, HLD, OA
O She suffered a TBI, multiple rib fractures,
PTX, tib-fib fx, splenic lac
O Intubated on MV
O HD#3 develops fevers to 103
O BMI is 45
Goals of Presentation
O Why is nutrition important
O Calculating nutritional needs
O Enteral vs Parenteral
O Gastric vs Post-pyloric
O Formulas
O Residuals
O Probiotics
Energy Use
O Initially when body not getting enough total
nutrients  fat used more the protein
O Glucose stores used up (small amounts of
glucose needed for fat metabolism)
O Amino acids then needed for
gluconeogenesis so lean body mass then
lost
O This becomes problematic in patients who
are nutritionally deplete prior to
hospitalization
Revved up systems
O In critically ill patients, body moves
into a hypercatabolic state
O Stress response
O In recovery, patients move into a
hyperanabolic state
O Need substrate to build back up
Hypermetabolism
O Metabolic rate increases 120-250% in brain
injured patients (even when sedated)
O SIRS-type response causing catecholamine
surge; catabolic hormones surge
O Increased needs for:
O Protein
O Lipids
O Carbs
Hypermetabolic State
O Increased Stress  Increased
Catecholamines  increases lipolysis and
gluconeogenesis
O Increased Stress  Increased Cortisol 
Increased lipolysis and proteolysis
Hyperglycemia
What is Malnutrition
O Altered intake of macro and
micronutrients
O Can lead to:
O Organ dysfunction
O Biochemical abnormalities
O Body mass index loss as lean
body mass is catabolized
O Immune dysfunction
How do we measure
nutritional status?
O Ideal body weight
O BMI
O Measure of body fat based on weight,
height
O Plasma proteins: need to compare with
positive APR
O Albumin – ½ life 2 weeks
O Prealbumin – ½ life 2 days
O Retinol binding protein – ½ life 12 hrs
O Transferrin
Nutritionally High Risk
O Increasing disease severity
O Pre-existing nutritional status
O Low BMI or recent weight loss
O Prolonged LOS
How do we know what our
patient’s need?
O First – calculate total fluid requirement
O 20-40ml/kg day
O Second – total energy requirement
O Most straightforward: 25-30kcal/kg/day
O Metabolic cart
O Harris-Benedict Equation = REE
(overestimates)
O Brain requires 20% of REE
O Clifton Equation
O 152-[14 x GCS] = 0.4 x HR + 7 x day since
injury
Harris-Benedict Equation
REE = basal metabolic rate
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
REE x CF
O Correction factors:
O Post-op: 1.1-1.5
O Sepsis: 1.3
O Multi-trauma: 1.5-
1.6
O Burns: 1.5-2
Metabolic Cart
O Measures VO2 (consumption)
and VCO2 over 10-30 minutes
O For accuracy, need intubated
patient at low FiO2 who is calm
O Can’t have any air leaks
O Dialysis can affect
Special Situations
O Sepsis
O Significant catabolic state
O Higher protein requirement
O Respiratory Failure
O RQ (CO2 production/O2 consumption)
O Renal Failure
O Liver Failure
O Extremes of BMI (<20 or >40)
Obese Patients
O Often fed later and inappropriately
O Increase protein (2-2.5g/kg/IBW)
O Decrease total requirement (65-70% of
caloric requirement)
Nitrogen Balance
Urinary nitrogen balance
O Each gram of nitrogen produced
requires 100-150kcal
O Patients with severe TBI who are
not fed can lose up to 25g
nitrogen/day
O Result is loss of up to 10% lean
body mass in 1 week
Where are nutrients absorbed?
O Most nutrients are absorbed in the
small intestines
O Water is absorbed in the stomach and
colon
O Vit K, Na+, Cl-, K+ and short chain
FA’s are absorbed in colon
Basics
O Carbs
O 30-70%
O Provides 4kcal/g
O Fat
O 20-50%
O Provides 9kcal/g
O Protein
O 15-20%
O Provides 4kcal/g
Enteral Nutrition
Data Behind EN
O EN within first 24-48 hours reduce infection,
LOS and mortality
O Delay of EN or interruption of feeding
produce significant calorie deficit
O Nurse driven protocols show earlier initiation
of nutrition and decreased mortality
Enteral vs Parenteral
O Enteral is preferred route
O Preserves GI barrier
O Maintains integrity of intestinal villi
O Reduces gut bacterial translocation
O Increased uptake of glutamine
despite decreased intake
Gastric vs. Post-pyloric
O Gastric feeds (especially bolus) simulate normal
intake
O Gastric feeding allows body to regulate transition of
food to duodenum and insulin release
O Gastric feeding allows better regulation of gastric pH
O Gastric is preferred unless:
O Patient unable to sit >30 degrees
O Ileus
O Residuals >500
O Post-pyloric
O Need slower titration of rates to prevent dumping
syndrome
Trophic vs Full Feeds?
O Study of ARDS pts showed no difference in
oucomes in trophic (25% of calories) vs full
feeds
O Trophic feeds for up to 6 days does not show
harm (select patient populations)
Choosing an Enteral Formula
O Formulas with arginine, fish oil and
nucleotides are helpful in elective surgery
pts
O Anti-inflammatory lipids and omega-3s
helpful in ARDS
TPN
O Consider parenteral nutrition if patient unable to
tolerate enteral feeds by day 7
O Need dedicated line
O Dextrose is major source of calories
O Lipids provide essential FA’s
O Max administration of 5-7g/kg/day
O Amino Acids
O Additives
O Electrolytes
O Vitamins
O Trace elements
O 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
O 20-40ml/kg or 1ml/kcal
O Most tube feed formulas are 70- 80% free
water
O Example: 70kg patient with large amount of
insensible losses
O 40ml/kg x 70kg = 2800ml fluid requirement
O Getting tube feeds at 70ml/hr = 1680ml/day
of which 1344 is free H2O
Probiotics
O Competitive inhibition of pathogens
O Stimulate physical gut barrier and mucous
production
O Reduce adherence and attachment of
pathogens
O Produce proteins that bind pathogens
O Stimulate T-cell production and increased
secretory IgA
What about Glutamine
Used for hepatic urea synthesis
Renal ammoniagenesis
Gluconeogenesis
Respiratory fuel for cells
Precursor for glutamate, excitatory
neurotransmitter  increased seizure
risk
O Also produces glutathione, a potent
anti-oxidant
O
O
O
O
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Feeding on Pressors
Residuals
O Slowed gastric motility – up to
50% of mechanically ventilated
patients
O Stopping feeds based on GRV?
Gastric Residuals
O Compare effects of increasing GRV from
200500ml
O Randomized 329 patients
O GRV measured every 8 hours on EN day #2
and then daily
O Reglan given to all pts during first 3 days of
EN
Gastric Residuals
O Gastrointestinal complications:
O Abdominal distention
O High GRV: 200 vs 500ml
O Vomiting
O Diarrhea
O Aspiration
Gastric Residuals
O Incidence of complications higher in the
control group
O Diet volume ratio similar in both groups (diet
received/diet prescribed)
Summary
O Nutrition is vitally important in ICU
patients
O Understand the nutritional needs of
your patients
O Calculate requirement and/or get a
nutrition consult
O Use the gut whenever possible
O Nutrition should commence by day 3
and not later than day 7