Nurtition

Question 1

Discuss nutritional support in the ICU

Answer 1

Most patient in the ICU are unable to tolerate peroral nutrition
Even this is able to be delivered by way of NG tube conditions such as ileus, gut fistulae or malabsorption syndrome may prevent adequate nutrition

On top of this acute phase inflammation and hormonal changes associated with critical illness affect

Question 2

Describe formula to estimate basic energey expenditure in ICU

Answer 2

BEE = 25x bodywieght

Some modification can be made to adjust for stress states

BEEx1.1 (for each degree above normal body temperature)
BEE x1.2 for mild to moderate stress
BEE x1.4 for severe stress

Question 3

Discuss substrates used

Answer 3

Carbs

• principal fuel source in CNS
• more then 400g per day results in de-novo lipogenesis which may be accompanied by an excessive CO2 production

Lipids

• Highest energy yield
• should provide approximatley 30% of daily energy needs
• the only dietary fatty acid that is considered essential and must be exogenously provided is linoleic acid.
• deficiency in linoleic acid may result in a scaly dermopathy and cardiac dysfunction

Protein
Should match protein breakdown can be estimated
-normal metabolism 1g/kg
-hypercatabolism 2-3g/kg

Question 4

Discuss methods of providing nutrition

Answer 4

Can be enteral or perenteral
Caloric requirements are the same for both
most ICU will initially start with NG feeding due to reduction in side affects
Can consider starting perenteral feeds 24-48 hours after intubation in patient that were previously malnoruished otherwise should be 7 days

Indications include

• mechanical bowel obstruction
• prolonoged ileus
• high volume entero-cutanous fisulas,
• short bowl syndrome
• possibly pancreatitis

Question 5

Discuss enteral nutrition

Answer 5

Complete bowel rest is accompanied by progressive atrophy and disruption of bowel mucosa which reduces its ability to act as a barrier to invasive enteric micro-organisms

Should be used in HD stable patient without bowel obstruction who are expected to be unable to take oral nutrition for more than 72hours

Standard NG tubes 14-16 french are good initial tubes as allows gastric aspiration and monitoring of stasis. however long term may cause pressure necrosis and finer tubes 8-10 are preferable

Can consider endoscopically guided tube into duodenum to help with stasis

Formulas are generally lactose free as starvation and malnutrition commonly result in a relative lactase deficiency

The risk of nosocomial pneumonia assoicated with microaspiration can be reduced by nursing in the 30 degree head up

Question 6

Discuss parenteral nutrition

Answer 6

• used through CVC
• can be assoicated with electrolyte and glycaemic imbalance and requires close monitoring of the same
• infection