Catheter Related Complications

Thrombosis

There are a number of factors that can increase the risk of thrombosis of a central line, including but not limited to:

Length of time the catheter has been in place
Complicated insertion
Small diameter of the vessel
Patient coagulopathy
Catheter material
Larger diameter of the central venous catheter

In addition to thrombosis, a catheter may become occluded.

Occlusion may be due to fibrin deposition, elements of parenteral nutrition such as calcium or phosphate precipitates, drug precipitates, or lipids from PN solution. To prevent occlusion episodes proper flushing technique should be used.

Infection

Central venous catheter related infections are very common in the intestinal failure patient population. The most common causative organism is coagulase-negative Staphylococcus, followed by Enterococcus, Staphylococcus aureus, and Candida sp. (2) Early catheter infections (within 45 days of placement) are usually caused by skin organisms migrating from the insertion site, while later infections are caused by infection through the lumen beginning from the catheter hub.

In all patients with a central venous catheter presenting with fever and/or other signs of a CVC related infection, blood cultures should be taken from both the central line and peripherally with prompt commencement of broad-spectrum antibiotics thereafter.

Metabolic Dysfunction

Chronic dehydration is common in the intestinal failure population and is an indication for intestinal transplant. It is common for intestinal failure patients to require additional fluids on top of parenteral nutrition. In short bowel patients with large enteric losses, it may be hard to replete stores of calcium, magnesium, and potassium.

It is important for patients to maintain stringent input and output records in order to adequately assess what are required hydration needs. Suggestive clinical findings of chronic dehydration include postural hypotension, weak pulse with tachycardia, subtle reductions in skin turgor, and lethargy.

Laboratory findings may show elevations in hematocrit, elevations in BUN or albumin, and/or presence of concentrated urine.

Enteral intake of food and fluids actually increases stool output and tendency for dehydration for three main reasons:

Consumption of hypotonic fluids, particularly water, produces a lumen-directed sodium gradient that draws water into the lumen.
Additional luminal fluid is produced by the osmotic draw of unabsorbed nutrients.
Food in the upper GI tract stimulates motility of the bowel remnant, increasing stool output.

In order to minimize dehydration, patients should be encouraged to drink oral rehydration solutions with sodium concentrations of at least 90 mEq/L. (2) Most often supplemental IV fluids are required on top of TPN requirements.

Patients with a colon in anatomic continuity will be much more likely to be able to maintain hydration status due to the water preserving properties of the colon. When a patient does have a colon, the use of anti-motility agents such as loperamide, diphenoxylate-atropine, and tincture of opium can be beneficial in prolonging transit timing an increasing fluid and nutrient absorption. Additionally, the use of the bile acid binding agent cholestyramine may further reduce colonic water losses and help control dehydration.

Hyperglycemia may occur in parenteral nutrition patients, especially those with diabetes or those who frequently become septic. Hyperglycemia can lead to lipogenesis which is associated with hepatic steatosis and other effects of hyperinsulinemia. (2) The inclusion of lipids in the TPN formula can be advantageous in reducing the amount of carbohydrate required without reducing the calories provided.

Organ Dysfunction

Liver disease and cholelithiasis are both possible complications from long term parenteral nutrition. There also is a spectrum of metabolic bone diseases that are seen with long term parenteral nutrition use, including, osteomalacia, osteoporosis, osteopenia, and secondary hyperparathyroidism. Patients with chronic intestinal failure and PN use should be screened for these conditions with bone density scans and serum measurements of markers such as calcium, vitamin D, magnesium, phosphorous, and PTH.

Factors that influence the long-term survival of parenteral nutrition patients include:

Primary diagnosis
Age
Remnant bowel length
Type/ anatomy of remaining bowel

References:

1. Langnas AN, Goulet O, Quigley EMM, Tappenden KA. Intestinal Failure Diagnosis, Management, and Transplantation. Malden, MA: Blackwell; 2008.

2. Tappenden KA. Pathophysiology of Short Bowel Syndrome. Journal of Parenteral and Enteral Nutrition. 2014;38(1_suppl). doi:10.1177/0148607113520005.