Nutrition Support: Sean P Harbison MD
Nutrition Support: Sean P Harbison MD
Nutrition Support: Sean P Harbison MD
Sean P Harbison MD
Metabolism
Glycogen stores are depleted 24-36 hours
after a major catabolic insult
Increased protein catabolism leads to loss
lean body mass
Nitrogen losses can exceed 15-20 grams/day
in the early sages of sepsis and trauma
During prolonged starvation the brain
switches from glucose to ketones as a fuel
source
Patient Selection
Unable to meet nutrient needs orally
Extended time frame NPO or inadequate
intake
Severe dysphagia
Critically ill patients who can not take PO
for several days/weeks/months
Early enteral support ideal in ICU patients
Energy Requirements
Hundreds of predictive equations
Variables in equations: height, weight,
age, gender
Harris Benedict commonly used
25-30 kcal/kg/day meets the needs of
most patients ( 70kg = 2100Cal/day)
Indirect Calorimetry--- Gold Standard
unwieldy, not clinically applicable
Energy Requirements
Hundreds of predictive equations
Variables in equations: height, weight,
age, gender
Harris Benedict commonly used
Men: BEE=65+(6.2xW)+(12.7xH)-(6.8xA)
Indirect Calorimetry
Metabolic Cart
Measurement of gas exchange across the
lung to determine REE
Respiratory quotient can assist with
adjusting substrate provision
RQ is calculated from the ration of CO2
produced over O2 consumed
Interpretation
Severe burns
Sepsis
Dialysis
Pressure ulcers
Non-healing wounds
Overfeeding Problems
Hepatic dysfunction/steatatosis
Hyperglycemia
Increased infection risk
Prolonged Intubation
Risk refeeding syndrome
Refeeding Syndrome
Consequences of depletion, repletion, and
compartmental shifts of glucose, fluid,
potassium, phosphorous, & magnesium
May occur with aggressive kcal provision
in malnourished patients
Low phosphorous level is the hallmark
symptom
Minimizing Complications
Recognize patients at risk
Replete potassium, magnesium, and
phosphorous levels PRN
Monitor levels closely
Avoid overfeeding: start low & go slow
Initial nutrition support goal conservative
Protein Requirements
Dependent on disease, treatment plans
& nutritional status
1.5-2.0 g/kg/day for critically ill patients
Avg: .8g/kg/day (~60 gm/day)
Severely injured trauma/burn patients
may require up to 2.5 g/kg/day
Hepatic Proteins
Albumin, Prealbumin, Transferrin
Hepatic reprioritization due to stress
Inflammatory markers (CRP)
Visceral proteins
Increased visceral protein levels if nutrition
provision adequate w/ resolution stress,
inflammation
Serum Proteins
In critical illness, low levels of albumin &
prealbumin reflect severity of illness
Inflammatory metabolism results in
decrease synthesis
Low albumin levels predictive of postoperative morbidity and mortality
Nitrogen Balance
Limits to Study
Accuracy 24 hr urine collection
Renal failure
Abnormal losses
excessive diarrhea
fistula output
wound & CT drainage
Enteral Support
Enteral support if GUT deemed functional
Adequately resuscitated
Hemodynamcially stable
Ideal to initate enteral nutrition the first
24-48 hrs
Advance to goal as able 48-72 hrs
Enteral v Gastric feeds
Contraindications to Enteral
Nutrition
Paralytic ileus
Severe short bowel syndrome
Active GI bleed
Severe GI malabsorption as evidenced by
deterioration nutrition status
Nonoperative mechanical GO obstruction
Enteral Products
Isotonic
Osmolite: Extended time frame NPO or extensive
GI surgery
Do not always have to initiate feeds with Osmolite!
Polymeric
Promote & Promote w/fiber
Jevity 1.2
Osmolite 1.5
Specialty Formulas
Disease Specific
Nepro
Glucerna 1.2
Oxepa
TF GOALS
Products range from 1.0-2.0 kcal/cc
16.7 25% kcal as protein
Identify goal at start of enteral nutrition
Osmolite: 60 cc/hr x 24 hrs = 1526 kcal & 64 gm protein
Promote: 60 cc/hr x 24 hrs= 1440 kcal & 90 gm protein
Nepro: 60 cc/hr x 24 hrs= 2592 kcal & 117 gm protein
Starting TF
Diffuse peritonitis
GI ischemia
Intestinal obstruction; unable to bypass
Intractable vomiting/diarrhea
Decreased intestinal absorptive area
Ileus
Nutrient needs exceed what can be met via
GI tract
Unable to obtain access to GI tract
TPN Criteria
Challenges
Shortages
Substrates
Electrolytes
Trace elements
Must provide 20 grams lipids per liter PN
Can hold lipids in PN
TPN Calculations
* 3.4 kcal per gm dextrose
* 4.0 kcal per gm protein
* 10 kcal per gm lipid
Example:
115 g protein (460 kcal)
250 g CHO
(850 kcal)
50 g lipids
(500 kcal)
1810 kcal
Volume Requirements
Make sure it fits!
115 g protein: 767 ml (15% AA)
250 g CHO: 357 ml (70% dextrose)
50 g lipids: 250 ml (20% lipids)
100 ml for additives
TPN Restrictions
Initial TPN Rx: 150 gm CHO or less
Standard Low CHO solution usually
appropriate for initial TPN
3-5 mg CHO/kg/minute (stressed patients)
Lipids contraindicated if TG > 400
Lipid content 30% or less total kcal
Monitoring TPN
Weekly
LFTs
TG
Prealbumin
Daily
BMP, Phos, magnesium
Accu check levels & I/Os
Monitoring TPN
Adjust based on daily labs
May need to adjust for acid-base
disturbances
When increasing volume TPN, remember
additives are ordered per liter
If TPN abruptly discontinues, provide D10
to prevent rebound hypoglycemia
TPN Complications
Liver dysfunction
Hyperglycemia
Loss of access
Infection
Metabolic bone disease (long-term)
Tapering TPN
Decrease TPN if TF at 33-50% goal rate
Typically decrease TPN rate by half when
TF at 50% goal
Decrease volume & macronutrients
Can D/C TPN if TF tolerated at 75% goal
rate
General Guidelines
Modification Nutrition
Non-healing wounds
Pressure ulcers
Fistula
Declining prealbumin
Negative nitrogen balance
Start PO
Nocturnal TF
References
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McClave SA, et al. Guidelines for the provision and assessment of nutrition
support therapy in the adult critically ill patient. SCCM & ASPEN. JPEN.
2009;33:277-316
ASPEN Board of Directors. Guidelines for the use of parenteral and enteral
nutrition in adult and pediatric patients. Journal of Parenteral and Enteral
Nutrition. 2002; 26:90SA-91SA
ASPEN nutrition support core curriculum, Gottschlich MM, ed. ASPEN,
Silver Spring, MD;2007.
Romano, M. (Presenter). (2011, July, 7). Enteral Nutrition. Lecture
presented at Nutrition Support Review Course: ASPN Clinical Nutrition
Webinar Series.
Derenski, K. (Presenter). (2011, July, 14). Parenteral Nutrition. Lecture
presented at Nutrition Support Review Course: ASPEN Clinical Nutrition
Webinar Series.
Cresci, G. (Presenter). (2011, July 28). Critical Care. Lecture presented at
Nutrition Support Review Course: ASPEN Clinical Nutrition Webinar Series.
Fisher, S. Nutrition. The practice ABSITE question book. Breinigsville,
PA.;2010