TPN in ICU
23/10/10
SP Notes
OH
PY Mindmaps
Smith, P. J. et al (2010) “Parenteral Nutrition” British Journal of Hospital Medicine, Vol 17
(12) page M185-M189
INDICATIONS = unable to establish enteral feeding
General
- EN contraindicated (have low threshold to use perioperatively depending on nutritional
state)
- EN fails to meet nutritional requirements
Specific
-
prolonged bowel obstruction and ileus
short bowel syndrome with severe malabsorption
severe dysmotility
high output intestinal fistulae
anastomotic break down
intolerance to EN
GENERAL
- ensure adequate central venous access (subclavian lines have lowest infection rates –
aseptic insertion, 2% chlorhexidine in alcohol, permeable polyurethane dressings,
antimicrobial catheters)
- dedicated lumen for TPN (daily infusion set changes)
- if requires TPN for > 2 months -> consider tunnelled line
- assess why patient cannot be enterally fed -> this is known to be safer
- 12 hourly reassessment of whether patient can be enterally fed
- requires close liaising with dietician and pharmacy
ASSESSMENT OF NUTRITIONAL STATUS (CALORIC REQUIREMENTS)
- calculate Resting Energy Expenditure (using the Harris-Benedict equation)
REE (males) = 66.5 + (13.7 x body weight in kg) + (5.0 x height in cm) (6.8 x age in years)
REE (females) = 66.5 + (9.6 x body weight in kg) + (1.7 x height in cm) (4.7 x age in years)
- use ideal body weight
- resting energy expenditure in calories
- multiply this by a stress factor to allow for effects of disease (no exercise = 1.2, very heavy
exercise BD = 1.9)
-
more accurate to measure REE by indirect calormetry
most hospitalized patients require 25-30kcal/kg/day
mechanically ventilated are on the lower aspect of range
burns and trauma patient may require 45kcal/kg/day
Jeremy Fernando (2011)
NUTRITIONAL REQUIREMENTS
Protein
- utilisation of exogenous protein = 1.5g/kg/day
- other techniques:
-> non-protein calorie to nitrogen ratio (100-200kcal/g of nitrogen often used)
-> nitrogen balance = (protein intake (g) / 6.25) – (urinary nitrogen (g) + 4) -> 4 =
empirical factor added to account for non-urinary nitrogen loss (faeces and sweat)
- cystalline solutions of L-amino acids (varying essential amino acids)
Carbohydrates
- daily requirement of glucose = 4-5g/kg/day in severely catabolic patients
Lipids
- requirements 1g/kg/day
- 1/3 of energy given as non-protein
- advantages: prevents fatty acid deficiency and provides more concentrated calories
- disadvantages: can cause pancreatitis, immunosuppression, overfeeding -> increase in CO2
production
- check lipids daily and check clearance of lipids
Minerals and Micronutrients
- Na+, K+, Ca2+, Mg2+, phosphate -> guided by serum plasma levels
- inorganic trace elements
- organic vitamins (thiamine, folic acid, fat soluble vitamins D, E, K, A, water soluble vitamins
B and C)
H2O
- 25-40mL/kg/day (+ losses)
MONITOR FOR COMPLICATIONS
-
catheter related sepsis
catheter occlusion
hyperglycaemia
hypercholesterolaemia
Jeremy Fernando (2011)
- refeeding syndrome (phosphate, K+, Mg2+)
- abnormal LFT’s
- trace elemental deficiency: > 2-4 weeks of poor nutrition
- copper: anaemia, neutropenia
- iodine: hypothyroidism
- chromium: glucose intolerance
- zinc: mental apathy, diarrhoea, rash
- selenium: cardiomyopathy
-> treatment: supplement, follow levels (serum, tissue, white cells)
PRESCRIPTION
-
total energy: 25 kcal/kg/day
protein: 1.5g/kg/day
carbohydrate: 4g/kg/day
lipids: 1g/kg/day
H2O: 30mL/kg/day + other losses
electrolytes
organic vitamins
inorganic trace elements
MY APPROACH
-
exhaust all means of feeding enterally
dietician involvement
calculate requirements (caloric and nutritional)
start slowly
monitor for refeeding and complications
frequent reassessment about whether patient can be fed enterally
Jeremy Fernando (2011)