Intravenous (IV) therapy delivers fluids, medications, and nutrients directly into a person’s bloodstream. This method allows for rapid distribution when oral administration is not feasible or effective. A common question is whether an IV is inserted into a vein or an artery. This article clarifies the distinct roles of these vessels and explains why one is chosen over the other for IV access.
Understanding Blood Vessels
The human body contains two primary types of blood vessels: arteries and veins. Arteries transport oxygenated blood away from the heart to the body’s tissues, except for the pulmonary artery. They possess thick, muscular, and elastic walls to withstand high pressure. Arterial blood flows rapidly and under significant pressure, appearing bright red due to its high oxygen content.
Veins, conversely, carry deoxygenated blood back towards the heart, with the exception of the pulmonary veins. Their walls are thinner and more pliable than arteries, due to lower pressure. Veins often have valves that help prevent blood from flowing backward, ensuring unidirectional movement towards the heart. Blood in veins typically flows more slowly and appears darker red. Arteries are generally located deeper within the body, while veins are often closer to the skin’s surface, making them more visible and accessible.
The Correct Vessel for IVs
Intravenous lines are consistently inserted into veins, a choice supported by several physiological advantages. A primary reason for this selection is the significantly lower blood pressure found in veins compared to arteries. This lower pressure reduces the risk of excessive bleeding, hematoma formation, or damage to surrounding tissues during and after insertion.
The thinner, less muscular walls of veins are also easier to cannulate, meaning a catheter can be inserted with less resistance and discomfort for the patient. Venous blood flow carries administered medications and fluids directly towards the heart, facilitating their rapid and systemic distribution throughout the body. Veins are more superficial and readily visible in areas like the hands and arms, making them easier for healthcare professionals to locate and access for successful IV placement.
Accidental Arterial Insertion
Despite careful practice, accidental insertion of an IV catheter into an artery can occur, leading to serious complications. Immediate signs that an artery may have been cannulated include the appearance of bright red blood that pulses or spurts rhythmically from the catheter, indicative of high arterial pressure. Patients often report intense pain or a burning sensation at the insertion site. The blood column within the IV tubing may also be seen moving upwards.
Such an event carries substantial risks due to the high pressure and different physiological role of arteries. Complications can include severe pain, tissue damage, and necrosis, especially if medications intended for venous administration are injected into an artery. There is also a risk of thrombosis, potentially compromising blood flow to the limb or digit beyond the insertion site. In severe cases, this can lead to limb ischemia, which may result in permanent damage or even limb loss if not promptly recognized and managed. Medical professionals undergo extensive training to identify and avoid arterial puncture, emphasizing the importance of proper technique in IV insertion.