Venous access

Venous access is any method used to access the bloodstream through the veins, either to administer intravenous therapy (e.g. medication, fluid), parenteral nutrition, to obtain blood for analysis, or to provide an access point for blood-based treatments such as dialysis or apheresis. Access is most commonly achieved via the Seldinger technique, and guidance tools such as ultrasound and fluoroscopy can also be used to assist with visualizing access placement. Peripheral venous catheter The most common form of venous access is a peripheral venous cannula which is generally inserted into veins of the hands, forearms, and occasionally feet. Healthcare providers may use a number of different techniques in order to improve the chances of successful access. Some techniques include using a tourniquet, tapping over the vein, warming the area to dilate the vein, or using an ultrasound to directly visualize the target vein. Near-infrared illumination devices can also be used to help identify superficial veins that are not easily felt or seen with the naked eye. These devices emit infrared light which is absorbed by hemoglobin in the blood, allowing for easier visualization of the vasculature. Peripheral access is usually indicated when short-term access up to 7 days is needed. Complication rates from these peripheral access points increase quickly the longer they remain in place (such as inflammation of the veins), and thus are routinely removed and replaced every 3–4 days if possible. Central venous catheter In some situations, venous access is obtained by inserting catheters into the large central veins of the trunk of the body such as the internal jugular, subclavian, or femoral veins. This type of venous access is performed with central venous catheters (CVCs), and is required in certain situations where peripheral access is inadequate. Such situations include, but are not limited to, the need for long-term venous access (for weeks or months, not days), administering of medications that can damage smaller veins (e.g.