Intravenous feeding is used when the digestive tract cannot adequately absorb nutrients, as occurs in severe malabsorption disorders Overview of Malabsorption Malabsorption syndrome refers to a number of disorders in which nutrients from food are not absorbed properly in the small intestine. Certain disorders, infections, and surgical procedures can... read more . It is also used when the digestive tract must be temporarily kept free of food, as is needed during certain stages of ulcerative colitis Ulcerative Colitis Ulcerative colitis is a chronic inflammatory bowel disease in which the large intestine (colon) becomes inflamed and ulcerated (pitted or eroded), leading to flare-ups (bouts or attacks) of... read more .
Food given intravenously can provide part of a person's nutritional requirements (partial parenteral nutrition), supplementing the food eaten by mouth. Or it may provide all of a person's nutritional requirements (total parenteral nutrition).
Parenteral nutrition requires a large intravenous tube. The tube (called a central venous catheter) must be inserted into a large vein, such as the subclavian vein, which is located under the collarbone. Parenteral nutrition may be used at home or in the hospital.
Total parenteral nutrition may be required in people with the following:
A digestive tract that is not functioning
Severe pancreatitis Overview of Pancreatitis Pancreatitis is inflammation of the pancreas. The pancreas is a leaf-shaped organ about 5 inches (about 13 centimeters) long. It is surrounded by the lower edge of the stomach and the first... read more or certain stages of ulcerative colitis Ulcerative Colitis Ulcerative colitis is a chronic inflammatory bowel disease in which the large intestine (colon) becomes inflamed and ulcerated (pitted or eroded), leading to flare-ups (bouts or attacks) of... read more
In children, diarrhea Diarrhea in Children Diarrhea is a very common problem in children (see also Diarrhea in adults). Diarrhea is frequent, loose, or watery bowel movements (BMs) that differ from a child’s normal pattern. Sometimes... read more that has lasted a long time, regardless of its cause
Short bowel syndrome Short Bowel Syndrome Short bowel syndrome is a disorder causing diarrhea and poor absorption of nutrients ( malabsorption), which often occurs after surgical removal of a large portion of the small intestine. This... read more due to surgical removal of a large part of the small intestine
Compared with tube feeding Tube Feeding Tube feeding may be used to feed people whose digestive tract is functioning normally but who cannot eat enough to meet their nutritional needs. Such people include those with the following... read more , intravenous feeding causes more complications, does not preserve the structure and function of the digestive tract as well, and is more expensive. Intravenous feeding is usually not the first choice for nutritional support when the digestive tract is functioning.
Procedure for Intravenous Feeding
Because the central venous catheter must remain in place for a long time, infections are a risk. To reduce the risk, health care practitioners 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 every day
Change the dressings that hold the catheter in place every other day
Using the catheter only for intravenous feeding also helps reduce the risk of infection.
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, under the collarbone. The catheter may be inserted into a vein in the neck if it is to be used only during a hospital stay.
Catheter in a Chest Vein for Feeding
This figure shows the blood vessel (subclavian vein) in the chest that can be used for intravenous feeding.
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 Complete blood count Doctors select tests to help diagnose blood disorders based on the person's symptoms and the results of the physical examination. Sometimes a blood disorder causes no symptoms but is discovered... read more ), and levels of electrolytes Overview of Electrolytes More than half of a person's body weight is water. Doctors think about water in the body as being restricted to various spaces, called fluid compartments. The three main compartments are Fluid... read more and other minerals, blood sugar, and urea (a waste product normally removed by the kidneys). They also do blood tests to evaluate protein levels and liver function (liver tests Liver Blood Tests Liver tests are blood tests that represent a noninvasive way to screen for the presence of liver disease (for example, viral hepatitis in donated blood) and to measure the severity and progress... read more ) 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 every 2 weeks.
If total parenteral nutrition is given outside the hospital, the person is taught to recognize the symptoms of infection, and home nurses visit regularly to check for problems.
In the standard formula for intravenous feeding, carbohydrates provide most of the calories. Formulas may also contain water, protein Proteins Carbohydrates, proteins, and fats are the main types of macronutrients in food (nutrients that are required daily in large quantities). They supply 90% of the dry weight of the diet and 100%... read more , fats Fats Carbohydrates, proteins, and fats are the main types of macronutrients in food (nutrients that are required daily in large quantities). They supply 90% of the dry weight of the diet and 100%... read more , vitamins Vitamins and Minerals The human body needs various vitamins and minerals in order to thrive. Many of these nutrients can be found in whole, non-processed foods such as fruits and vegetables. However, most modern... read more , and minerals Vitamins and Minerals The human body needs various vitamins and minerals in order to thrive. Many of these nutrients can be found in whole, non-processed foods such as fruits and vegetables. However, most modern... read more . Essential amino acids Proteins Carbohydrates, proteins, and fats are the main types of macronutrients in food (nutrients that are required daily in large quantities). They supply 90% of the dry weight of the diet and 100%... read more (components of protein) and essential fatty acids Fatty acids Carbohydrates, proteins, and fats are the main types of macronutrients in food (nutrients that are required daily in large quantities). They supply 90% of the dry weight of the diet and 100%... read more (components of fat) are also included. These nutrients are called essential because the body cannot make them from other nutrients. Thus, they must be consumed in the diet.
However, different formulas can be used based on test results, other disorders present, the person's age, and other factors, as for the following:
For people with kidney failure when dialysis is not being used or for people with liver failure: A formula with less protein but a high percentage of essential amino acids
For people with heart or kidney failure: A formula with less fluid
For people with respiratory failure: A formula with less carbohydrate and more fat, which is added to provide the needed amount of calories (processing fat is less work for the lungs than processing carbohydrates)
For newborns: A formula with less sugar
For obese people: A formula with less fat
Complications of Intravenous Feeding
Intravenous feeding can cause problems related to the central venous catheter or to the formula, 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 Sepsis and Septic Shock Sepsis is a serious bodywide response to bacteremia or another infection plus malfunction or failure of an essential system in the body. Septic shock is life-threatening low blood pressure ... read more . 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 Hypoglycemia Hypoglycemia is abnormally low levels of sugar (glucose) in the blood. Hypoglycemia is most often caused by medications taken to control diabetes. Much less common causes of hypoglycemia include... read more ) 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 Overview of Electrolytes More than half of a person's body weight is water. Doctors think about water in the body as being restricted to various spaces, called fluid compartments. The three main compartments are Fluid... read more ). 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 Overhydration Overhydration is an excess of water in the body. People can develop overhydration if they have a disorder that decreases the body’s ability to excrete water or increases the body's tendency... read more ) can cause fluid to collect in the lungs, making breathing difficult. Too little water results in dehydration Dehydration Dehydration is a deficiency of water in the body. Vomiting, diarrhea, excessive sweating, burns, kidney failure, and use of diuretics may cause dehydration. People feel thirsty, and as dehydration... read more . 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 may try to calculate the amount of water required before feedings are started.
Problems due to formulas that contain more fat and fewer carbohydrates (called lipid emulsions) occasionally occur. These problems include difficulty breathing, allergic reactions, nausea, headache, back pain, sweating, and dizziness. Fat (lipid) levels in the blood may increase temporarily, especially in people with kidney 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 Preterm (Premature) Newborns A preterm newborn is a baby delivered before 37 weeks of gestation. Depending on when they are born, preterm newborns may have underdeveloped organs that are not be ready to function outside... read more with respiratory distress syndrome Respiratory Distress Syndrome in Newborns Respiratory distress syndrome is a lung disorder in premature newborns in which the air sacs in their lungs do not remain open because a substance that coats the air sacs called surfactant is... read more 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 formula.
Liver problems can develop in people of any age but are most common among infants, particularly premature ones (whose liver is immature). Doctors do blood tests to measure levels of liver enzymes and thus evaluate how well the liver is functioning. Reducing the amount of protein in the formula may help. If the liver is enlarged and painful, the amount of carbohydrate is reduced. If liver problems develop in infants, ammonia may accumulate in the blood. If ammonia accumulates, symptoms may include sluggishness, seizures, and twitches in muscles. Giving the infant an amino acid (arginine) supplement can correct this problem.
Bone density may decrease if intravenous feeding lasts more than 3 months. Osteoporosis Osteoporosis Osteoporosis is a condition in which a decrease in the density of bones weakens the bones, making breaks (fractures) likely. Aging, estrogen deficiency, low vitamin D or calcium intake, and... read more or osteomalacia (due to a deficiency of vitamin D Vitamin D Deficiency Vitamin D deficiency is most commonly caused by a lack of exposure to sunlight. Some disorders can also cause the deficiency. The most common cause is lack of exposure to sunlight, usually when... read more ) 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 Gallstones Gallstones are collections of solid material (predominantly crystals of cholesterol) in the gallbladder. The liver can secrete too much cholesterol, which is carried with bile to the gallbladder... read more or sludge. Stones may block a duct, causing inflammation (cholecystitis Cholecystitis Cholecystitis is inflammation of the gallbladder, usually resulting from a gallstone blocking the cystic duct. Typically, people have abdominal pain, fever, and nausea. Ultrasonography can usually... read more ). Increasing the amount of fat in the formula and not giving sugar for several hours a day can stimulate contractions in the gallbladder and thus help move accumulated substances on their way. Giving food by mouth or through a tube inserted in the nose may also help. Drugs, such metronidazole, ursodeoxycholic acid, phenobarbital, or cholecystokinin, may be used to stimulate gallbladder activity.