Intravenous (IV) means ‘into or within a vein’. The term is used to describe any substance, fluid or medication delivered directly into the bloodstream via a needle or catheter inserted into a vein, bypassing the digestive system and ensuring immediate availability to the circulation. IV administration provides the fastest route for drug delivery and is essential for emergency treatment where rapid effect is required.
In the context of cardiac arrest and critical illness, IV access is one of the first priorities. Paramedics typically establish IV access in a peripheral vein (usually the arm or hand) during resuscitation, allowing emergency drugs such as adrenaline and amiodarone to be administered. In hospital, patients admitted to the intensive care unit following cardiac arrest will have a central venous catheter (CVC) inserted into a large central vein (usually the internal jugular, subclavian or femoral vein), which provides more reliable access for vasopressor drugs, concentrated medications, and fluid management that would damage peripheral veins.
Common IV medications given in post-cardiac arrest care include sedatives and analgesics (to keep ventilated patients comfortable), vasopressors (to maintain blood pressure), antiarrhythmics, antibiotics, and nutrition (total parenteral nutrition, or TPN, if the gut cannot be used). IV fluids including saline and balanced crystalloid solutions are used to support circulating volume. The rate and type of IV fluid given is carefully titrated based on clinical observations, blood pressure measurements and urine output.
Peripheral IV cannulas (usually called ‘drips’ or ‘cannulas’) are short plastic tubes inserted into a peripheral vein. They are re-sited every 72 to 96 hours to reduce the risk of phlebitis (vein inflammation) and infection. Once a patient is able to tolerate oral medication and fluids, IV lines are removed. Patients occasionally notice bruising, tenderness or mild swelling at previous cannula sites after discharge, which usually resolves within a few days.
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