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Nutrition
Edward Melkun
February 5, 2007
Overview
Nutrition plays key role in recovery
 Discussion of changes during critical
illness
 Parenteral and Enteral Nutrition

Acute Phase Response
Changes in AA metabolism
 Increased acute phase proteins
 Increased gluconeogenesis
 Fever
 Negative nitrogen balance

AA metabolism
Cytokines and inflammatory mediators
circulate to liver
 Inhibit albumin synthesis and increase
acute phase proteins (ex. CRP)
 Also circulate to brain and act on
hypothalamus to increase core temp, and
increase ACTH

Insulin Resistance
Decrease in body glucose oxidation and
increased liver gluconeogenesis
 Increased ketogenesis
 Rise in serum cortisol leads to insulin
resistance
 Increased catecholamines, glucogon, and
growth hormone also lead to elevated
serum glucose

Increased Catabolism
Critically ill patients may lose 16-20g
nitrogen in the urine per day (nl is 1012g)
 1g of urea equal to about 1oz. Of skeletal
muscle
 May result in impaired respiratory muscle
strength, heart and gi function

Use of Proteins
Leukocytes have decreased half life of 4-6
hours during infection
 Increased acute phase proteins
 Average critically ill adult can break down
and resynthesize 400g of protein in 24
hours.

Nutritional Assessment
History – 10% weight loss or more suggests
protein malnutrition
 Exam – Weight/Ideal body weight (<85%
predicted), temporal muscle wasting,
anthropometrics
 Nutritional markers
-daily weight – more a measure of fluid status than nutritional

status
-24 hour urine urea nitrogen (cannot be used in renal failure)
-albumin 21, prealbumin 2, transferrin 7
-albumin influenced by fluid status, acute phase
response
Nutritional Assessment
Immune function – skin testing, anergy
 Predictors of outcome - albumin <3.4 related to increased mortality in VA

study, linear correlation, APACHE III score factors in
albumin
- caloric intake predicts survival when matched
for serum albumin level
Nutritional Therapy
Resting Energy Expenditure – linked to
lean body mass
 Accurate calculation can be done with
metabolic cart, estimated by HarrisBenedict

Adult males:
 BEE (kcal/day) = 66 + (13.7 x wt in kg) + (5 x ht in cm) - (6.8 x age).
Adult females:
 BEE (kcal/kcal) = 655 + (9.6 x wt in kg) + (1.7 x ht in cm) - (4.7 x age).
Nutritional Therapy
Healthy adult – approx 25 kcal/kg/day, 1g
protein/kg/day
 Pretty sick to moderately sick – 30
kcal/kg/day, 1.5g protein/kg/day
 Very sick – 35 kcal/kg/day, 2g
 Very Very sick - ? 40 kcal/kg/day, ?2.5g

EN vs. PN

If the gut works, use it
 Prevents
gut atrophy, translocation, reduced
infections, better maintenance of serum
albumin, reduced mortality despite equal
caloric intake
 Indications for TPN – short gut, high output
fistula, hyperemesis gravidarum
 Increased rates of infection and complications
may be due to failure to maintain tight
glucose control
Enteral Nutrition
FT placement ideally in small bowel
 Theoretical decrease in incidence of
aspiration
 CDC recommends feeding patients with
HOB elevated to reduce risk
 Theoretical decreased risk in patients with
cuffed ET tube

Parenteral Nutrition
3 liters of fluid necessary to give enough
calories via PPN due to limitations on
dextrose content due to phlebitis risk
 Dextrose administration should not exceed
3.5mg/kg/min to avoid metabolic
complications
 Fats – Septic patients have decreased
ability to utilize dextrose, but use fats well

 Also
prevents essential fatty acid deficiency
TPN
Complications associated with TPN include
increased serious infections including catheter
infection, venous thrombosis
 Metabolic complications include –


Volume overload, Essential fatty acid deficiency,
Hyperglycemia, Trace mineral deficiency, Refeeding
syndrome, Vitamin deficiency, Hypokalemia, Metabolic
bone disease, Hypophosphatemia, Hepatic steatosis
Hypomagnesemia, Hepatic cholestasis,
Hyperchloremic acidosis
TPN
TPN given at supratheraputic caloric levels
of 39kcal/kg/day and 1.8g/kg/day protein
did not show any anabolism or increase in
lean body mass.
 Still continued to lose 24g of nitrogen in
average day
 Pts were able to increase fat stores
 TPN can slow catabolism but not increase
anabolism
