How do physicians decide whether to order IV heparin drips or SC heparin for patients

It depends on the clinical reason for the Heparin. Heparin 5,000 units subcutaneous injection q12hr or q8hr are typically for deep vein thrombosis (DVT) prevention.

A Heparin drip is used for several reasons:

DVT treatment - the patient is started on this and it is titrated until their Ptt is therapeutic (60-80), then they are started on Coumadin and that dose is titrated until the INR is therapeutic (2-3). When the INR is therapeutic the Heparin drip is d/c'd.

Pulmonary Embolism (PE) - VQ scans with a high probability result will usually mean that you'll need to start a Heparin drip. I think spiral CTs are replacing the VQ scan as the diagnostic tool of choice.

Pre-op patient who was previously on Coumadin. Heparin has a shorter half-life than Coumadin. It is possible and sometimes necessary to have a patient admitted prior to surgery and on a Heparin drip so as to continue anti-coagulating without the Coumadin on board. This way the Heparin drip can be stopped for about 4hrs prior to surgery and the risk of developing new clots or excessive post-op bleeding is decreased.

Understanding half-life, onset and duration of your meds is important when determining/anticipating what med to give or hold. Your drug guide should also give you a list of routine dosages and indications/usage for this and other meds.

Congratulations and welcome to nursing.

The other issue that you have to take into account is that with Heaprin IV, you can reverse it with Protamine. With Heparin SQ, it has a much longer absorption time depending on the the amount of fat in the patient's abdomen, etc., so it is much harder to try to reverse. You are usually also giving higher doese of Heparin with the IV form, on average about 1,000 units per hour vs 5,000 units every 8 or 12 hours with the SQ.

Great posts everyone.