Energy expenditure

Energy expenditure can be assed in the ICU by three methods

1. Indirect calorimetry
2. The Fick principle (in patients with a PA catheter in situ)
3. Predictive equations

The Schofield equation can be used to determine basal metabolic rate.

This can be adjusted for stress e.g. severity of infection / burns and activity e.g. bed-bound / mobile

Age (years)	Female	Male
15-18	13.3/kg + 690	17.6/kg + 656
18-30	14.8/kg + 485	15/kg + 690
30-60	8.1/kg + 842	11.4/kg + 870
>60	9/kg + 656	11.7/kg + 585

 

Protein requirements

There is an upper limit to the amount of protein that can be used for synthesis – no benefit in over-supplementation.

A daily protein provision of 1-1.25 grams of protein per kilo per day is recommended.

Severely hypercatabolic individuals (e.g. major burns) can be given up to 2 grams of protein per kilo per day

Micronutrients

Critical illness increases the requirements for vitamins A, E, K, B₁, B₃, B₆, C , pantothenic acid and folic acid.

Renal replacement therapy can cause loss of water-soluble vitamins