An intravenous (IV) catheter is a common medical tool consisting of a small, flexible tube inserted into a patient’s vein to provide direct, immediate access to the bloodstream. The device allows healthcare providers to bypass the digestive system entirely, ensuring treatments are delivered quickly and effectively throughout the body. This technology is widely used across all areas of medical care, from emergency rooms to routine hospital stays. The catheter itself is typically made of flexible plastic and is left within the vein after a guiding needle, or trocar, is removed.
Primary Functions of Intravenous Catheters
The primary function of an IV catheter is to administer necessary substances directly into the circulatory system. This route is used for hydration and correcting electrolyte imbalances by delivering intravenous fluids. It ensures rapid absorption, which is useful when a patient is unable to take fluids by mouth or requires immediate volume replacement.
The catheter also allows for the administration of a wide variety of medications, including antibiotics, chemotherapy agents, and pain relief. Certain drugs must be delivered intravenously because they are poorly absorbed orally or require a high concentration quickly. IV access also facilitates rapid blood transfusions and frequent blood sampling without repeated needle sticks.
Peripheral Versus Central Catheters
Intravenous access is categorized by the location of the catheter tip within the venous system. A peripheral IV (PIV) is the most common type, inserted into smaller veins, typically in the hand or forearm. PIVs are designed for short-term use and are suitable for most standard fluids and non-irritating medications. The tip of a PIV rests in a peripheral vein and does not extend to the central vessels.
A central venous catheter (CVC), or central line, is a longer access device placed in a larger vein, such as the internal jugular, subclavian, or femoral vein. Its tip terminates near the heart in one of the body’s largest veins, often the superior or inferior vena cava. This placement allows for the safe infusion of highly concentrated solutions or those with an abnormal pH, which would damage a smaller peripheral vein.
Central lines are reserved for long-term treatments, caustic medications like chemotherapy, or extensive intravenous nutrition. A peripherally inserted central catheter (PICC) is a subtype of CVC, inserted into a peripheral arm vein but threaded up into the central circulation. The choice depends on the medication type, treatment duration, and the patient’s vein health.
The Insertion Procedure
The process for placing a standard peripheral IV begins with identifying a suitable vein, often aided by a tourniquet applied above the site. The selected site is then thoroughly cleaned with an antiseptic solution to prevent bacteria from entering the bloodstream. Once prepared, the healthcare provider stabilizes the vein and inserts the catheter-over-needle assembly, which includes a sharp, hollow needle, or trocar, inside the flexible plastic tube.
A “flashback” of blood into the catheter chamber confirms successful entry into the vein. The provider advances the flexible plastic portion, known as the cannula, a few millimeters further. The needle is safely withdrawn and locked into a protective guard mechanism, leaving only the cannula inside the vessel. Finally, the catheter hub is connected to an extension set and secured firmly to the skin with a sterile dressing and tape to prevent movement.
Monitoring and Post-Placement Complications
Once the IV catheter is secured, monitoring the insertion site is necessary to identify potential issues. One common local complication is infiltration, which occurs when the catheter tip slips out of the vein, causing fluid or medication to leak into the surrounding subcutaneous tissue. Signs of infiltration include swelling, coolness around the site, and a slowing of the infusion rate.
Another complication is phlebitis, the inflammation of the vein wall, often caused by mechanical irritation from the catheter or chemical irritation from the infused solution. Phlebitis presents with warmth, localized redness, pain, and tenderness along the vein path. If the vein wall becomes hardened and cord-like, it suggests a pronounced inflammatory reaction.
Signs of a localized infection include excessive pain, warmth, swelling, or purulent discharge at the insertion site. Patients should immediately notify medical staff if they experience these symptoms, as early catheter removal and appropriate treatment are necessary. Maintaining a clean, secure dressing helps minimize the risk of infection.