Venous Access

Mayur Patel, MD Danny O. Jacobs, MD, MPH

Obtaining access to the venous vasculature is one of the most common procedures performed. Generally, catheters provide the conduit to permit the introduction or withdrawal of fluid, medications, or blood products. In order to determine catheter type, size, and placement, the intention for intravenous (IV) access must be known.

IV access can be required for many reasons, urgent and nonurgent, including delivery of fluid (crystalloid or colloid), blood products, total parental nutrition (TPN), and medications like antibiotics, chemotherapy, and pressor therapy. Catheters threaded near cardiac venous inflow, central venous catheters (CVCs), can provide right atrial pressure monitoring, blood drawing capability, as well as a passage for invasive cardiac monitoring (Swan-Ganz) or transvenous cardiac pacing.

Once the patient's IV need is determined, a peripheral versus central location can be addressed. Peripheral IV (PIV) access is the most common IV access method for short-term use. PIV catheters are short (less than 8 cm), inserted over a needle, through the skin into a peripheral vein, usually in the extremities. Uncommonly, venous cutdown is required for PIV placement. PIV catheters can be used for maintenance of IV fluid and medication delivery. Fourteen- to sixteen-gauge PIVs provide rapid volume delivery due to their relative short length and large diameter (resistance a length/radius4), as compared to long, multilumen CVCs. PIV catheters are replaced every 72-96 h. When not in use, these catheters require a heparin lock IV (HLIV) or a low basal rate (10-30 mL/h) of maintenance fluid infusion (KVO, keep vein open). Rarely, PIVs are associated with bloodstream infections; however, phlebitis can occur with long-term use.

CVCs are long (longer than 8 cm) and percutaneously inserted over a guidewire (Seldinger technique, Fig. 18-7) into central veins, such as the sub-clavian, internal jugular, or femoral veins. Ultrasound and/or fluoroscopy can assist in CVC placement. Once inserted, the ideal position of the catheter tip is the junction between the right atrium and the superior vena cava (SVC). The average distance from skin to right atrium is 14.5 and 18.5 cm, for right- and left-sided cannulations, respectively. Maximal barrier precautions are mandatory during placement. Also, specialized CVC teams help decrease serious complications.

Despite best efforts and depending on location, improper CVC placement can cause pneumothorax, hemothorax, arterial or nerve injury, cardiac dys-rhythmia, air embolism, catheter embolization, or thrombosis. Importantly, in patients with a prior pneumothorax or hemothorax, it is safer to attempt CVC placement on the ipsilateral injured side. This avoids harming the uninjured side and risking bilateral pneumothorax or hemothorax. It is vital that a chest x-ray be completed after any subclavian or internal jugular CVC placement or attempt (unnecessary for femoral CVC access).

Unfortunately, CVCs cause the majority of serious catheter-related infections, especially those occurring in the intensive care unit (ICU). Skin flora is the origin of most CVC infections. Early infection (3-5 days) usually results from infection of the subcutaneous tract. Later infections may have the same cause or may occur by hematogenous spread. Staphylococcus epidermidis and Staphylococcus aureus are the most common bacteria cultured. Contamination of the catheter hub contributes substantially to intraluminal colonization of CVCs. Multilumen catheters and catheter thrombosis both increase the incidence of catheter sepsis. To decrease infection risk, certain catheters are coated or impregnated with

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