Page 537 - ACCCN's Critical Care Nursing

514 P R I N C I P L E S A N D P R A C T I C E O F C R I T I C A L C A R E

TABLE 19.7 Short-term metabolic complications associated with total parenteral nutrition

Complication Cause Detection and treatment
Hyperosmolar coma Occurs acutely if a rapid infusion of hypertonic fluid is Daily blood samples, accurate measurements of fluid
administered. Infusion can cause severe osmotic diuresis, balance, routine blood samples. Reduce infusion
resulting in electrolyte abnormalities, dehydration and rate, correct electrolyte imbalances.
malfunction of the central nervous system.
Electrolyte Disturbances in serum electrolytes, particularly sodium Daily blood samples taken early in treatment to
imbalance potassium, urea and creatinine, may occur early in the detect abnormalities. Replacement fluid as
treatment of TPN. Electrolyte imbalances can be caused by required, extra intravenous fluids may be required
the patient’s underlying medical condition; requirements during the stabilisation period.
vary with individual patients’ needs. Can be caused by
inadequate or excessive administration of intravenous fluids.
Hyperglycaemia Critically ill patients may be resistant to insulin because of the Monitor the patient’s blood sugar 4-hourly after
secretion of ACTH and adrenaline. This promotes the commencement of treatment or as required.
secretion of glycogen, which inhibits the insulin response to Monitor daily urinalysis for glucose and ketones.
hyperglycaemia. An insulin infusion may be required to keep blood
sugar levels within prescribed limits.
Rebound May occur on discontinuation of TPN because hyperinsulinism Glucose infusion rate should be gradually reduced
hypoglycaemia may occur after prolonged intravenous nutrition. A rise in over the final hour of infusion before
serum insulin occurs with infusion, and thus sudden discontinuing. Some patients may receive a 10%
cessation of infusion can result in hypoglycaemia. glucose solution after cessation of TPN.
Hypophosphataemia Glucose infusion results in the continuous release of insulin, Monitor phosphate levels daily. Hypophosphataemia
stimulating anabolism and resulting in rapid influx of will usually appear after 24–48 hours of feeding.
phosphorus into muscle cells. The greatest risk is to Reduce the carbohydrate load and give phosphate
malnourished patients with overzealous administration of supplementation.
feeding. Patients who are hyperglycaemic, who require
insulin therapy during TPN or who have a history of
alcoholism or chronic weight loss may require extra
phosphate in the early stages of treatment.
Lipid clearance Lipids are broken down in the bloodstream with the aid of Blood samples should be taken after the first
lipoprotein lipase found in the epithelium of capillaries in infusion commences (within 6 hours) to observe
many tissues. A syndrome known as fat overload syndrome for lipid in the blood.
can occur when infusion of lipid is administered that is
beyond the patient’s clearing capacity, resulting in lipid
deposits in the capillaries.
Side effects of lipid Some patients suffer symptoms either during or after an Treat mild symptoms. If tolerated, the TPN solution of
infusion infusion of lipid mix parenteral nutrition. The exact cause is non-protein calories can be given in the form of
unknown. The patient may complain of headache, nausea or glucose. However, it is essential that the regimen
vomiting, and generally feels unwell. includes some fat to prevent the development of
fatty acid deficiency.
Anaphylactic shock This is a rare complication but may occur as a reaction to the It may be necessary to administer adrenaline and/or
administration of a lipid. steroids, and to provide supportive therapy as
required.
Glucose intolerance TPN using glucose as the main source of calories is associated Observe patients for signs of respiratory distress.
with a rise in oxygen consumption and CO 2 production. The Provide non-protein calories in the form of glucose
workload imposed by the high CO 2 production may lipid mix. Slow initial rate of infusion.
precipitate respiratory distress in susceptible patients,
particularly those requiring mechanical ventilation.
Liver function Abnormalities with liver function can be associated with TPN. Monitor liver function tests twice weekly. There are
May be attributable to hepatic stenosis with moderate several factors that may contribute to
hepatomegaly; patient may also develop jaundice. Liver development of abnormal liver function tests.
function tests often return to normal after cessation of These most often occur after a period of time and
therapy; however, TPN can lead to severe hepatic appear to be more of a problem when there is an
dysfunction in neonates. excess calorie intake or in glucose-based regimens.
ACTH = adrenocorticotrophic hormone.

heterogeneity of the patient populations. 195 With occult nasogastric lavage positive for bright red blood is used as
bleeding (drop in haemoglobin level or positive stool an endpoint to describe clinically overt bleeding. 198,199
occult blood test) as an endpoint, it is estimated that The incidence of clinically significant bleeding, that is
15–50% of critically ill patients would be reported to bleeding associated with hypotension, tachycardia, and a
have stress-related mucosal damage. 196,197 Reported inci- drop in haemoglobin level necessitating transfusion, is
dence is reduced to 25% or less when haematemesis or estimated to be 3–4%. 194