Central Administration
When a critically ill patient requires parenteral nutritional
support because of gut dysfunction, a central catheter should be inserted (subclavian
vein). A 15% dextrose (1,400 mOsm/L) solution containing 4% to 5% amino acids can
be combined with 500 mL of fat emulsion. This provides balanced parenteral nutrition
by administration of 50% of the nonprotein calories as fat and 50% as dextrose.
Another approach is to provide all the calories as dextrose at a rate 4 to 5 mg/kg/min
and replace essential fatty acids with 500 mL of fat emulsion three times per week.
Central venous catheter complications ( Table
77-7
) limit the usefulness of intravenous nutrition administered by this
method. Multilumen catheters for central venous insertion are also attractive for
parenteral nutrition because one lumen may be dedicated to the nutritional media,
which is highly bacteriophilic, and other lumens may be used for pressure monitoring
or drug administration. Other complications of TPN are outlined in Table
77-8
. Complications of TPN include misplacement of feeding tubes, regurgitation
or vomiting along with pulmonary aspiration, frequent interruptions of feedings leading
to significant undernutrition, and diarrhea.
