Heparin Drip: Protocol & Calculation

Instructor: Julie Eiler
Heparin is an anticoagulant drug used to prevent complications from existing or impending blood clots. This lesson overviews the purpose of heparin infusions and the general protocol for administration and monitoring.

Grandma's blood clot

A young man brings his grandmother into the emergency room for treatment. His grandmother's left leg is swollen, red, and warm. When you touch the back of her calf she jumps from pain. You notice a healing incision on her leg, and the young man reveals that his grandmother recently had knee replacement surgery. You have some suspicions, but a few simple imaging tests reveal that indeed his grandmother has a blood clot in her leg. This is a serious condition not only because the blood clot is affecting good blood flow in her leg, but because a blood clot can detach and travel through the vessels to the lungs, heart or brain. The physician writes orders to admit the woman to the hospital, and the meantime starts a very important infusion to keep her problem from becoming worse-- heparin.

Blood Clots (Thrombus)

When trauma occurs to tissue, the formation of clots prevents the loss of too much blood. However clots formed inside vessels due to blockage or poor circulation (like laying in bed for long periods during a hospital stay) can prevent blood from getting to vital organs like the brain, heart, or kidneys. Clots can also break away and travel to the brain or lungs causing a stroke or a pulmonary embolus.

This image shows a blood clot occluding a blood vessel.

Imagine blood as cars driving down the highway (blood vessels). A road blockade that keeps you from driving off a fallen bridge could save your life, but a disabled vehicle in the middle of the road may cause a collision and prevent the ambulance from getting through!

Heparin as a Continuous Infusion

Heparin is an injectable drug known as an anticoagulant, meaning it prevents or delays blood's ability to clot. Heparin is used in healthcare to prevent serious complications that can be caused by blood clots. Heparin works by inactivating the enzyme, thrombin, that causes blood to clot. Heparin may be used to prevent clots, for example after surgery or after having a heart attack, or to allow blood to move more freely around an existing clot.

Heparin is a high-risk drug that requires strict dosing and monitoring when given intravenously, or directly into the bloodstream. Individual organizations generally have protocols for managing these drips. Most heparin drips, or continuous infusions, are dosed using the patient's weight because body fat affects the way heparin works. They are also dosed based on the indication. For example, you would likey give a higher dose for an existing clot, while a lower dose in the case of prevention. Heparin infusion rates are calculated in units per hour, and adjusted up or down depending on the patient's blood work. The blood value used to determine rate is called PTT, or partial thromboplastin time. This value represents how long it takes blood to clot. The physician and pharmacist ordering the infusion set a desired therapeutic range for this lab value to fall within.

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