Hemoperfusion

Definition
Purpose
Description
Preparation
Normal results
Risks

Definition

Hemoperfusion is a treatment technique in which large volumes of the patient’s blood are passed over an adsorbent substance in order to remove toxic substances from the blood. Adsorption is a process in which molecules or particles of one substance are attracted to the surface of a solid material and held there. These solid materials are called sorbents. Hemoperfusion is sometimes described as an extracorporeal form of treatment because the blood is pumped through a device outside the patient’s body.

The sorbents most commonly used in hemoperfusion are resins and various forms of activated carbon or charcoal. Resin sorbents are presently used in Europe but not in the United States; since 1999, all hemoperfusion systems manufactured in the United States use cartridges or columns containing carbon sorbents. A newer type of cartridge containing an adsorbent polymer has been undergoing clinical tests in the United States since the summer of 2002.

Purpose

Hemoperfusion has three major uses:

• to remove nephrotoxic drugs or poisons from the blood in emergency situations (a nephrotoxic substance is one that is harmful to the kidneys);
• to remove waste products from the blood in patients with kidney disease; and
• to provide supportive treatment before and after transplantation for patients in liver failure.

Hemoperfusion is more effective than other methods of treatment for removing certain specific poisons from the blood, particularly those that bind to proteins in the body or are difficult to dissolve in water. It is used to treat overdoses of barbiturates, meprobamate, glutethimide, theophylline, digitalis, carbamazepine, methotrexate, ethchlorvynol, and acetaminophen, as well as treating paraquat poisoning. Paraquat is a highly toxic weed killer that is sometimes used by people in developing countries to commit suicide.

Description

A hemoperfusion system can be used with or without a hemodialysis machine. After the patient has been made comfortable, two catheters are placed in the arm, one in an artery and one in a nearby vein. After the catheters have been checked for accurate placement, the catheter in the artery is connected to tubing leading into the hemoperfusion system, and the catheter in the vein is connected to tubing leading from the system through a pressure monitor. The patient is given heparin at the beginning of the procedure and at 15-20-minute intervals throughout the hemoperfusion in order to prevent the blood from clotting. The patient’s blood pressure is also taken regularly. A typical hemoperfusion treatment takes about three hours.

Hemoperfusion works by pumping the blood drawn through the arterial catheter into a column or cartridge containing the sorbent material. As the blood passes over the carbon or resin particles in the column,

KEY TERMS

Adsorb— To attract and hold another substance on the surface of a solid material.

Clearance— The rate at which a substance is removed from the blood by normal kidney function or by such methods as hemoperfusion.

Extracorporeal— Occurring outside the patient’s body.

Heparin— A complex sugar compound used in medicine to prevent the formation of blood clots during hemodialysis, hemoperfusion, and open-heart surgery.

Nephrotoxic— Destructive to kidney cells. Hemoperfusion can be used to remove nephrotoxic chemicals from the blood.

Paraquat— A highly toxic restricted-use pesticide. Death following ingestion usually results from multiple organ failure.

Sorbent— A material used during hemoperfusion to adsorb toxic or waste substances from the blood. Most hemoperfusion systems use resin or activated carbon as sorbents.

the toxic molecules or particles are drawn to the surfaces of the sorbent particles and trapped within the column. The blood flows out the other end of the column and is returned to the patient through the tubing attached to the venous catheter. Hemoperfusion is able to clear toxins from a larger volume of blood than hemodialysis or other filtration methods; it can process over 300 mL of blood per minute.

Preparation

In emergency situations, preparation of the patient may be limited to cleansing the skin on the inside of the arm with an antiseptic solution and giving a local anesthetic to minimize pain caused by the needles used to insert the catheters.

The hemoperfusion system is prepared by sterilizing the cartridge containing the sorbent and rinsing it with heparinized saline solution. The system is then pressure-tested before the tubing is connected to the catheters in the patient’s arm.

Normal results

Normal results include satisfactory clearance of the toxic substance or waste products from the patient’s blood. The success of hemoperfusion depends in part, however, on the nature of the drug or poison to be cleared from the blood. Some drugs, such as the tricyclic antidepressants, enter the tissues of the patient’s body as well as the bloodstream. As a result, even though hemoperfusion may remove as much as 80% of the drug found in the blood plasma, that may be only a small fraction of the total amount of the drug in the patient’s body.

Risks

The risks associated with hemoperfusion are similar to those for hemodialysis, including infection, bleeding, blood clotting, destruction of blood platelets, an abnormal drop in blood pressure, and equipment failure. When hemoperfusion is performed by a qualified health professional, the risks are minor compared to the effects of poisoning or organ failure.

Resources

BOOKS

“Dialysis.” In The Merck Manual of Diagnosis and Therapy, 18th ed. Edited by Mark H. Beers, Robert S. Porter, Thomas V. Jones, Justin L. Kaplan, and Michael Berkwits. Whitehouse Station, NJ: Merck Research Laboratories, 2006.

“Elimination of Poisons.” In The Merck Manual of Diagnosis and Therapy, 18th ed. Edited by Mark H. Beers, Robert S. Porter, Thomas V. Jones, Justin L. Kaplan, and Michael Berkwits. Whitehouse Station, NJ: Merck Research Laboratories, 2006.

Nissenson, Allen R., and Richard N. Fine. Clinical Dialysis, 4th ed. New York: McGraw-Hill Professional, 2005.

PERIODICALS

Borra, M., et al. “Advanced Technology for Extracorporeal Liver Support System Devices.” International Journal of Artificial Organs 25 (October 2002): 939–949.

Cameron, R. J., P. Hungerford, and A. H. Dawson. “Efficacy of Charcoal Hemoperfusion in Massive Carba-mazepine Poisoning.” Journal of Toxicology: Clinical Toxicology 40 (2002): 507–512.

Hsu, H. H., C. T. Chang, and J. L. Lin. “Intravenous Paraquat Poisoning-Induced Multiple Organ Failure and Fatality: A Report of Two Cases.” Journal of Toxicology: Clinical Toxicology 41 (2003): 87–90.

Reiter, K., et al. “In Vitro Removal of Therapeutic Drugs with a Novel Adsorbent System.” Blood Purification 20 (2002): 380–388.

OTHER

Deshpande, Girish G. “Toxicity. Carbamazepine.” eMedicine. February 13, 2008. http://www.emedicine.com/ped/topic2732.htm (April 21, 2008).

Kirkland, Lisa, and Alan W. Horn. “Toxicity, Theophylline.” eMedicine. January 11, 2007. http://www.emedicine.com/med/topic2261.htm (April 21, 2008).

ORGANIZATIONS

American Academy of Emergency Medicine, 555 East Wells Street, Suite 1100, Milwaukee, WI, 53202-3823, (800) 884-2236, http://www.aaem.org.

Center for Emergency Medicine of Western Pennsylvania, 230 McKee Place, Suite 500, Pittsburgh, PA, 15213, (412) 647-5300, http://www.centerem.org.

National Kidney Foundation, 30 East 33rd Street, NewYork, NY, 10016, (212) 889-2210, (800) 622-9010, http://www.kidney.org.

Society of Toxicology, 1821 Michael Faraday Drive, Suite 300, Reston, VA, 20190, (703) 438-3115, http://www.toxicology.org.

Rebecca Frey, Ph.D.

Laura Jean Cataldo, R.N., Ed.D.