Vascular Access Glossary: Terms, Abbreviations & Definitions

A clinician-reviewed glossary of vascular access terms and abbreviations — VAD, CVAD, PICC, CLABSI, DIVA, VHP, vesicant, fibrin sheath, MARSI, and more — with concise, evidence-based definitions.

Resource For clinicians
By Dennis Woo, Dr. Mike Stern & I.M. Wright 4 min read

This glossary defines the core terms and abbreviations used across vascular access and infusion therapy practice. Definitions are concise and clinician-reviewed, and align with the Vascular Access pillar and the Vascular Access Guidelines & CPGs hub.

Vascular Access Device (VAD)
Any catheter, cannula, or needle used to access the vascular system to deliver fluids, medications, blood products, or nutrition, to draw blood, or to monitor the circulation.
Central Vascular Access Device (CVAD)
Any vascular access device whose tip terminates in the central venous system (lower superior vena cava or cavoatrial junction). Includes PICCs, non-tunneled and tunneled CVCs, and implanted ports.
Peripheral Intravenous Catheter (PIV)
A short catheter inserted into a superficial peripheral vein, typically in the hand or forearm, for short-term infusion of non-irritating solutions.
Midline Catheter (Midline)
A catheter inserted into a peripheral vein of the upper arm with its tip ending in the axillary or basilic vein below the thorax — peripheral access for moderate-duration, non-vesicant therapy.
Peripherally Inserted Central Catheter (PICC)
A central venous catheter inserted through a peripheral arm vein (commonly the basilic) with its tip positioned at the lower SVC or cavoatrial junction; suitable for weeks-to-months of therapy including vesicants, TPN, and IV antibiotics.
Central Venous Catheter (CVC)
A catheter placed directly into a central vein (internal jugular, subclavian, or femoral). Non-tunneled CVCs are used for short-term ICU access and urgent central access.
Tunneled Central Catheter (e.g., Hickman, Broviac, Groshong)
A surgically tunneled CVAD in which the catheter passes through a subcutaneous tract before entering the vein, reducing infection risk and supporting months-to-years of home infusion, oncology, or long-term TPN.
Implanted Port (Port-a-Cath)
A fully implanted CVAD consisting of a reservoir under the skin connected to a central catheter, accessed through the skin with a non-coring (Huber) needle; ideal for intermittent long-term therapy such as chemotherapy.
Hemodialysis Catheter (HD catheter)
A large-bore, dual-lumen central catheter used as a bridge or chronic access for hemodialysis; tunneled for longer-term use.
Arterial Line (A-line)
A catheter placed in an artery (commonly radial or femoral) for continuous hemodynamic monitoring and arterial blood gas sampling.
Intraosseous Access (IO)
Emergency vascular access established into the bone marrow cavity when peripheral or central IV access cannot be obtained quickly; intended for short-term use.
Central Line-Associated Bloodstream Infection (CLABSI)
A laboratory-confirmed bloodstream infection in a patient with a central line in place, not related to an infection at another site; a key NHSN-reported, preventable healthcare-associated infection.
A clinical diagnosis of bloodstream infection attributed to an intravascular catheter, confirmed by quantitative or differential-time-to-positivity cultures; the clinical counterpart to the surveillance term CLABSI.
Phlebitis (VIP scale)
Inflammation of a vein — chemical, mechanical, or bacterial — graded 0 to 5 on the Visual Infusion Phlebitis (VIP) scale; the most common complication of peripheral IV therapy.
Infiltration
Inadvertent leakage of a non-vesicant solution into the surrounding tissue from a dislodged or failed catheter.
Extravasation
Inadvertent leakage of a vesicant solution into surrounding tissue, which can cause blistering, tissue necrosis, and lasting injury; a vascular access emergency.
Vesicant
A medication or solution capable of causing tissue necrosis or blistering if it escapes the vein; vesicants generally require central venous administration.
Catheter Occlusion
Partial or complete blockage of a catheter lumen — thrombotic, mechanical, or precipitate-related — that impairs infusion or aspiration.
Fibrin Sheath
A sleeve of fibrin and cellular material that forms around an indwelling catheter, a common contributor to withdrawal occlusion and a nidus for infection and thrombosis.
Difficult Intravenous Access (DIVA)
A validated scoring construct predicting the likelihood of failed peripheral IV placement; higher scores prompt early escalation to ultrasound guidance, midline, or PICC.
Vessel Health and Preservation (VHP)
A systematic framework for protecting a patient’s venous capital by matching the least invasive device to the therapy, duration, infusion characteristics, and the patient’s vessels.
Osmolarity
The concentration of solute particles in a solution; infusions at or above 600 mOsm/L generally warrant central access, and above 900 mOsm/L require it.
Cavoatrial Junction (CAJ)
The point where the superior vena cava meets the right atrium; the target tip position for most central vascular access devices.
Securement
The method used to stabilize a catheter and prevent dislodgement — engineered securement devices, sutureless securement, tissue adhesive, or integrated stabilization.
Needleless Connector (NC)
A device attached to the catheter hub that allows needle-free access for infusion and aspiration; design and disinfection practices directly affect CLABSI risk.
SASH (Saline-Administer-Saline-Heparin)
A flushing sequence used to maintain catheter patency: Saline flush, Administer medication, Saline flush, then Heparin lock where indicated.
Skin damage caused by medical adhesives such as dressings and securement devices, including tension blisters, skin tears, and contact dermatitis; often underreported.