Some medicines need to be delivered directly to the bloodstream via the patient's vein using a tube or needle – this is called an intravenous (IV) injection or infusion.
IV administation allows for multiple and extremely controlled doses of medication to be givento the patient, depending on what is required. To avoid the need to repeatedly insert an IV needle, a thin plastic tube can be inserted into the vein of the patient, called an IV catheter.
Drugs can be administered via IV in emergencies such as a stroke or heart attack, where they cannot be given via the oral-route in liquid or pill format, either because the patient is unconcious and unable to swallow, or because digestion would take too long to deliver the medicine into the blood.
IVs are also useful for medication that must avoid entering the stomach so that it is not broken down by the acid or enzymes there, which may prevent the medicine from working properly.
Typically used for up to four days, a needle is normally inserted into a vein in the patients back of the hand, wrist or elbow and a catheter is pushed over the needle. The needle is removed but the catheter stays in place. A standard IV is mostly used during surgery or to provide short term medication for pain, nausea or antibiotics.
There are two kinds of IV medication administration that use a standard IV catheter. An IV push (or bolus) administers a one-time dose of medication rapidly by injection via a syringe. An IV infusion is for more long-term medication administration, where a controlled amount enters the bloodstream over time. The medicine can be sent to the catheter either just by gravity (known as drip infusion) from a bag hoisted in the air or is pumped in so that the dosage can be precise and controlled (known as pump infusion).
Central venous catheters
If there is a long term need for medication to be administered, a central venous catheter (CVC) is used in place of a standard IV catheter. These are inserted into a vein in either the neck, arm, chest or groin. Due to these positions, a CVC can be used for weeks or even months.
There are three types of CVC’s. A peripherally inserted central catheter (PICC) is typically placed in a vein above the elbow, and has a long line that goes from the insertion area, through blood vessels to a vein near the heart. If it’s a tunneled catheter, one end of the catheter is surgically placed into a vein in the neck or chest, with the rest of the catheter ‘tunnelled’ through the body. The end comes out through the skin, where the medication is given.
An implanted port starts with a surgical procedure to put the catheter into a vein in the neck or chest, but no line is sent through the body, it stays entirely underneath the skin. The medication is injected through the skin into the port directly.