Parenteral nutrition refers to nutrients delivered to the patient in a manner other than through the gastrointestinal (GI) tract. This type of nutrition is used in the most critical patients which may have one or more of the following symptoms:
- Intestinal obstruction or ileus
- Inadequate digestive or absorptive capacity
- Uncontrollable vomiting (this is particularly life threatening to a diabetic animal)
- Inability to tolerate food for any reason (eg., head trauma, burns to mouth/face/esophagus)
- High risk of aspiration because the patient is unconscious or has a neurologic problem
- Need for complete GI tract rest due to digestive disease, healing time needed for GI tract lesions or surgical repairs, acute pancreatitis or hepatitis
Parenteral nutrition can be delivered to the patient by intravenous, intramuscular, subcutaneous, intraosseous or intraperitoneal routes, but the preferred method in veterinary medicine for the majority of patients requiring this type of nutrition is via a jugular intravenous catheter. The risk of infection is the greatest worry with this type of catheter and aseptic (sterile) technique must be used at all times. This type of support is generally given for a period of no more than 14 days, at which point the patient has hopefully begun to recover from the symptoms that caused the need for the catheter.
The solution fed through the catheter is a carefully balanced solution of dextrose, lipids, amino acids, electrolytes (which may be supplemented if needed by a peripheral catheter) and B-vitamins. The formulation is tailored to the patient's daily needs for calories, fluids and electrolytes, protein and whether the patient will do better getting the majority of its energy requirement from dextrose (sugar) or lipids (fats). Complete blood counts (CBC) and blood chemistrics are monitored at least daily to measure the patient's progress on the chosen solution and adjustments are made as needed.
This type of nutritional support can only be administered within the hospital due to the need to use sterile technique in handling the catheter and solution. Also, patients requiring this support are generally very critical and need the supervision of 24-hour intensive care support. This kind of care is given at Texas A&M's Intensive Care Unit where many critical patients have received parenteral nutritional support as part of their hospital care.
References:
Lon D. Lewis, Mark L. Morris, Jr. and Michael S. Hand. Intravenous feeding. Small Animal Clinical Nutrition III. p5-35, 1994.
Michael S. Hand, Craig D. Thatcher, Rebecca L. Remillard and Philip Roudebush. Parenteral Assisted Feeding. Small Animal Clinical Nutrition 4th Edition. p375, 2000.
J.M. Wills and K.W. Simpson. Parenteral Nutrition. The Waltham Book of Clinical Nutrition of the Dog and Cat. p49, 1994.
