Calculating the Medical Nutrition Therapy prescription in the ICU should incorporate consideration of all contributors to macronutrients and calories. This includes the IV propofol used for sedation.
Propofol, being highly lipid soluble, is formulated within an intravenous lipid emulsion and therefore contributes to the recommended maximum dose of lipid to be infused. Since propofol is frequently used as an infusion in the ICU, the accumulated contribution of fat and the associated calories can be substantial. Both overfeeding of energy and over-delivery of total fat are regarded as poor clinical practice1.
Understanding propofol formulation
Propofol may be delivered as a 1% (10mg/ml) or 2% (20mg/ml) formulation, both of which deliver 0.1g/ml of lipid in the form of 100% soy oil. However, 2% propofol delivers less fat because lower volumes are required to achieve the same sedative effect. The drug is also available in some regions as 1% or 2% propofol in 0.1g/ml of a 50/50 soy/MCT oil blend. NOTE: some formulations may not be available in your country. Find out what is used in your unit.
Calculating lipid delivered from propofol2
- Calculate total daily dose based on hourly infusion rate:
Hourly rate (ml) x 24 hours = total ml per 24 hours (adjust if hourly rate is not constant)
2. Calculate total fat contributed by 24 hour propofol volume
Total 24 hour volume (ml) x 0.1g = total grams fat per 24 hours
[Note: this amount of fat must be incorporated into the total daily fat from parenteral nutrition (PN). Calculate this back to g/kg.]
3. Calculate total calories provided by propofol infusion
Total ml per 24 hours x 1.1 kCal = total energy provided by fat from propofol
Note: this is secondary in importance to the control of total fat dose per day as in point 2 above – see example below.
Note: technically there is a fractional difference in the energy contribution between products, with 50/50 soy-MCT formulations contributing only ≈ 1.03kCal/ml
Example Calculation
Guidance on lipid dose and monitoring3
- Maximum IV lipid infusion dose is 1g/kg/day with tolerance of ≤ 1.5g/kg/day1
- Important Note: This 1g/kg/day is understood to be the upper limit for 100% soy IVLE (or alternatively restrict lipid to ≤30% total energy). For 100% soy there is also a maximum recommended infusion rate of ≤ 0.11g/kg/hr. Since propofol is delivered in 100% lipid, this rate and dose applies and should be calculated if 100% soy base propofol is being used. 0.1g/kg/hr of soy lipid is roughly equivalent to a propofol infusion rate of 1ml/kg/hr.
- However, mixed IV lipids (reduced soy content) are generally safe at up to a maximum of ≈ 1.7g/kg/day.
- Serum triglycerides should be monitored at baseline and then twice weekly while propofol infusion and/or PN continues.
- Maintain serum triglycerides <4.5mmol/l (and perhaps <3mmol/l when fish oil emulsions are used) by control of total lipid dose, glucose dose and choice of lipid type (avoid high soy). If serum triglyerides > 11mmol/l, provide a short (24-48hr) lipid holiday and then recommence, restricting total lipids to 1g/kg/day.
References:
- Singer et al ESPEN guideline on clinical nutrition in the intensive care unit Clin Nutr Feb 2019; 38 (1): 48-79
- Propofol and Propoven Product Information Monograph
- Raman et al Parenteral Nutrition and Lipids Nutrients 2017, 9; 388
