TPN vs. Enteral: Advantages?
Many prospective, randomized studies
TPN group had much higher infection rates
- pneumonia, intraabdominal abscess, line sepsis
Potential Reasons for TPN Failure
TPN increases blood glucose if not strictly controlled
numerous studies now show hyperglycemia increases mortality and infectious complications
Does not contain glutamine
Preservation of villous architecture
may prevent translocation
role of translocation unclear in humans
good study in BMT patients
Ability to give glutamine
major fuel of enterocytes
major nitrogen transfer agent to viscera
in catabolic stress may be an essential AA
In severely malnourished
Development of severe electrolyte abnormalities:
phosphorous, potassium, magnesium
As muscle mass, cell mass, and ATP repleted:
may reach critically low values, cardiac arrest
Consequences of Overfeeding
1. Azotemia - patients > 65 years and patients given > 2g/kg protein are at risk.
2. Fat-overload syndrome - recommended maximum is 1g lipid/kg/d. Infuse IV lipid slowly over 16 - 24 hours.
3. Hepatic steatosis - patients receiving high carbohydrate, very low fat TPN are at risk.
4. Hypercapnia - makes weaning difficult.
5. Hyperglycemia - increases risk of infection. Glucose should not exceed 5 mg/kg/min (4 mg/kg/min for diabetics).
6. Hypertonic dehydration - can be caused by high-protein formula with inadequate fluid provision.
7. Hypertriglyceridemia - propofol, high TPN lipid loads, and sepsis increase the risk. If the patient is hypertriglyceridemic, decrease lipid to an amount to prevent EFAD (500 cc 10% lipid twice weekly) and monitor.
8. Metabolic acidosis - patients receiving low ratios of energy to nitrogen are at risk. Acidosis can cause muscle catabolism and negative nitrogen balance.
9. Refeeding syndrome - common in malnourished patients or those held NPO prior to initiation of feeding. Start feedings conservatively, advance gradually, and monitor Mg, Ph, and K closely