a relatively large volume of fluid or dose of a drug or test substance given intravenously and rapidly to hasten or magnify a response; in radiology, rapid injection of a large dose of contrast medium to increase opacification of blood vessels.
a relatively large dose of medication administered into a vein in a short period, usually within 1 to 30 minutes. The IV bolus is commonly used when rapid administration of a medication is needed, such as in an emergency; when drugs that cannot be diluted, such as many cancer chemotherapeutic drugs, are administered; and when the therapeutic purpose is to achieve a peak drug level in the bloodstream of the patient. The IV bolus is not used when the medication must be diluted in a large-volume parenteral fluid before entering the bloodstream or when the rapid administration of a medication, such as potassium chloride, may be life-threatening. The IV bolus is normally not used for patients who have decreased cardiac output, decreased urinary output, pulmonary congestion, or systemic edema. Such patients have decreased tolerance to medications, which therefore must be diluted more than usual and administered at slower rates. A wristwatch with a second hand is recommended for the timing of all IV bolus injections. The amount of medication to be delivered per minute is determined by dividing the total amount to be injected by the prescribed time for delivery. The IV bolus site is prepared with an appropriate antiseptic, and sterile technique is used to enter the site with a venipuncture needle. A winged-tip needle is used for administering an IV bolus because it is small enough to lessen the risk of collapsing the vein and causing trauma and is more stable than a syringe needle. If a primary IV line is already established, the IV bolus is administered by mixing the prescribed drug with the appropriate amount of diluent and then administering the drug into the primary line, after first determining whether it is compatible with the primary IV solution. Also called intravenous push.
in·tra·ve·nous bo·lus(in'tră-vē'nŭs bō'lŭs)
1. A relatively large volume of fluid or dose of a drug or test substance given intravenously and rapidly to hasten or magnify a response.
2. radiology Rapid injection of a large dose of contrast medium to increase opacification of blood vessels.