Intravenous Feeding

Parenteral nutrition is a special liquid solution that is given through a tube called a central venous catheter. The catheter is inserted into a large vein, such as the subclavian vein, which is located under the collarbone.

To place the catheter, doctors insert a needle through the skin into the vein, then thread a guide wire through the needle. The needle is removed, and the catheter is passed over the guide wire, which is then removed. A small ultrasound device may be used to guide the placement of the catheter, and an x-ray may be taken afterward to confirm that the placement is correct. Often, the catheter is placed in the subclavian vein. The catheter may be inserted into a vein in the neck if it is to be used only during a hospital stay. Once the catheter is in place, the solution is delivered directly to the person's bloodstream where nutrients are absorbed by the body.

Because the central venous catheter must remain in place for a long time, infections are a risk. To reduce the risk, health care professionals use strict sterile techniques when inserting and maintaining the catheter. For example, they do the following:

• Clean the skin at the insertion point before inserting the catheter

• Change the tubing connecting the catheter to the bag of formula and change the in-line filter every day

• Change the dressings that hold the catheter in place every other day

Using the catheter only for intravenous feeding (and not, for example, for delivering intravenous medications) also helps reduce the risk of infection.

Intravenous Feeding (Parenteral Nutrition)

Parenteral nutrition is a special liquid solution that is given through a tube called a central venous catheter. The catheter is inserted into a large vein, such as the subclavian vein, which is located under the collarbone. Credit: DNA Illustrations/SCIENCE PHOTO LIBRARY

An interdisciplinary nutrition team (including a doctor, dietitian, pharmacist, and nurse), if available, should monitor the person's progress. They regularly measure body weight, the number of blood cells in blood (complete blood count), and levels of electrolytes and other minerals, blood sugar (glucose), and urea (a waste product normally removed by the kidneys). They also do blood tests to evaluate protein levels and liver function (liver tests) and keep track of how much fluid the person is getting and how much urine is excreted. A complete nutritional assessment, including calculating body mass index (BMI) and analyzing body composition, is done as often as needed. People who are critically ill may need more frequent assessments, whereas people who are stable and receiving parenteral nutrition at home need less frequent assessments.

If parenteral nutrition is given at home, the person and their caregivers are taught how to care for and clean the catheter and the skin around it, how to administer the solution and handle the bags it comes in, and how to recognize complications including symptoms of infection. Nurses regularly visit the person at home to check for problems.

When possible, intravenous feeding solutions are tailored to a person's individual needs. For example, based on a person's health status and laboratory test results, members of the nutrition team can adjust the levels of water, protein, fats, electrolytes (such as sodium and potassium), vitamins, minerals, essential amino acids (components of protein), and essential fatty acids (components of fat) in the solution. If a health care facility is not able to tailor a solution to a person's individual needs, the person is given a standardized solution that meets the needs of most people.

In addition to laboratory test results, the nutrition team uses a person's other characteristics, such as age and physical disorders, to determine what solution best suits their needs:

• For people with heart, liver, or kidney failure: A solution with less fluid

• For people with diabetes: A solution with a higher proportion of oils, so that fewer calories need to be provided by carbohydrates

• For newborns: A solution with fewer carbohydrates

• For people with obesity: Sometimes a solution with fewer calories

Intravenous feeding can cause problems related to the central venous catheter or to the solution, as well as other problems. Why some problems occur is unknown.

Injury during insertion of the catheter may occur. For example, a blood vessel, nerve, or lung may be injured.

Infections are more likely when an incision is made in the skin, as is needed to insert a catheter, especially when it is left in place a long time. (Normally, the skin helps prevent organisms that cause infection from entering the body.) Infections may spread to the bloodstream, and bloodstream infections can lead to a serious condition called sepsis. Using sterile techniques can help prevent infections.

A blood clot sometimes forms in the vein that the catheter is in.

Nutritional imbalances and deficiencies can occur during intravenous feeding. Blood sugar (glucose) levels that are too high (hyperglycemia) or too low (hypoglycemia) are relatively common. Rarely, deficiencies of certain vitamins and minerals occur. To identify these problems, doctors do blood tests to measure levels of sugar and minerals (electrolytes). They adjust the formula as needed and periodically recheck sugar and electrolyte levels.

Too much water (volume overload) or too little water may be given. Too much water (overhydration) can cause fluid to collect in the lungs, making breathing difficult. Too little water results in dehydration. Thus, doctors regularly monitor the person's weight and the amount of urine excreted. Blood tests to measure urea can help doctors identify dehydration. Disproportionately high levels may indicate dehydration. To the reduce the risk of water imbalances, doctors or nutrition professionals working with doctors calculate the amount of water required before feedings are started and adjust the amount as needed.

Problems due to solutions that contain fat (lipids) occasionally occur. These problems include difficulty breathing, allergic reactions, nausea, headache, back pain, sweating, and dizziness. Fat levels in the blood may increase temporarily, especially in people with kidney failure or liver failure. Later, the liver and/or spleen may enlarge, and people may tend to bleed and bruise more easily or develop infections more often. Premature infants with respiratory distress syndrome or other lung disorders are particularly at risk of these problems. To try to prevent or minimize these problems, doctors may temporarily or permanently slow or stop the solution.

Liver problems

Bone density may decrease if intravenous feeding lasts more than 3 months. Osteoporosis or osteomalacia (due to a ) may result. If advanced, these disorders can cause severe pain in the joints, legs, and back.

Gallbladder problems may develop or worsen when the gallbladder is inactive, as may occur during intravenous feeding. Substances (such as cholesterol) that are normally processed and moved through the gallbladder may accumulate, forming gallstones or sludge. Stones may block a duct, causing inflammation (cholecystitis