Nutrition

1
Nutrition

• Edward Melkun
• February 5, 2007

2
Overview

• Nutrition plays key role in recovery
• Discussion of changes during critical illness
• Parenteral and Enteral Nutrition

3
Acute Phase Response

• Changes in AA metabolism
• Increased acute phase proteins
• Increased gluconeogenesis
• Fever
• Negative nitrogen balance

4
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

5
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

6
Increased Catabolism

• Critically ill patients may lose 16-20g nitrogen
  in the urine per day (nl is 10-12g)
• 1g of urea equal to about 1oz. Of skeletal muscle
• May result in impaired respiratory muscle
  strength, heart and gi function

7
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.

8
Nutritional Assessment

• History 10 weight loss or more suggests
  protein malnutrition
• Exam Weight/Ideal body weight (lt85 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

9
Nutritional Assessment

• Immune function skin testing, anergy
• Predictors of outcome -
• - albumin lt3.4 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

10
Nutritional Therapy

• Resting Energy Expenditure linked to lean body
  mass
• Accurate calculation can be done with metabolic
  cart, estimated by Harris-Benedict
• 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).

11
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

12
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

13
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

14
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

15
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

16
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