Written and maintained by CASRAI Editorial Board
Published · Last updated
This page describes products and general use; it is not medical advice.
On this page
A saline lock is an IV catheter that stays in place with a short connector and cap on its hub instead of tubing and a running fluid bag. It is read by clinic staff, students and buyers who need to know what the set consists of and what published guidance says about the connector. Whether a patient gets a lock or a continuous infusion is a clinician’s order, not a purchasing choice.
What is a saline lock?
A saline lock (also called an intermittent infusion device) keeps a vein accessible between doses without fluid running continuously. A 1994 prehospital study in Prehospital and Disaster Medicine (Carducci and Stein) describes it as used “in place of traditional intravenous tubing and fluid bags” for IV maintenance. In that study the device was attached to the hub of the IV cannula. The authors concluded it was an effective method of maintaining prehospital IV access.
Who uses it: nurses, paramedics and other clinicians who give intermittent IV medication or need access held open; clinic staff and buyers who stock the components.
The lock is a configuration, not a single product. For the catheter itself see what an IV catheter is; for the flush that is used with it see what a saline flush is.
Saline lock vs continuous IV infusion
With continuous infusion, tubing connects the catheter to a fluid container (see IV infusion pumps and IV supplies). With a lock, the tubing and bag are replaced by a connector and cap, and the line is accessed only when something is given. Which setup applies is set by the clinician’s order and the patient’s needs. This page does not recommend one over the other.
Parts of a lock set
- Catheter (cannula): the device in the vein, ending in a hub.
- Connector or injection site: attached to the hub. CDC’s guideline calls these needleless connectors when they are used in a needleless system.
- Flush syringe: a prefilled syringe is the flush product used with the lock; see what a saline flush is.
- Cap and antiseptic for the access port: see the CDC guidance below and disinfecting caps.
Lock sets used with a closed system are covered in closed IV catheter systems.
What CDC says about the connector
The CDC/HICPAC Guidelines for the Prevention of Intravascular Catheter-Related Infections (2011; checked 2026-11-03) include these statements relevant to the connector on a lock. The guideline is from 2011, so treat it as a dated reference, not a statement of current practice.
| Topic | What the guideline says | Category |
|---|---|---|
| Connector change | Change needleless connectors “no more frequently than every 72 hours or according to manufacturers’ Recommendations” (the guideline’s own capitalization), for the purpose of reducing infection rates. | II |
| Compatibility | “Ensure that all components of the system are compatible to minimize leaks and breaks in the system.” | II |
| Port access | Scrub the access port with an appropriate antiseptic (chlorhexidine, povidone iodine, an iodophor or 70% alcohol) and access it only with sterile devices. | IA |
| Valve type | A split septum valve “may be preferred over some mechanical valves due to increased risk of infection with the mechanical valves.” | II |
| Needleless system | Use a needleless system to access IV tubing. | IC |
What to verify before you stock one
Only the criteria below come from the CDC guideline; anything else is for the clinical team and the product’s instructions for use (IFU).
- That the connector, catheter hub and flush product are compatible with each other (CDC compatibility statement).
- The manufacturer’s recommended connector change interval, since CDC defers to it.
- The valve type of the connector (split septum or mechanical), because CDC distinguishes them.
Safe use and handling basics
General handling from the CDC guideline: scrub the port before access, access it only with sterile devices, and follow the manufacturer’s interval for connector changes. Catheter insertion and flushing are clinical procedures taught and supervised in training; this page does not give steps.
Common mistakes
- Treating the lock and the flush as the same thing. The lock is the capped catheter and connector; the flush is the saline used with it.
- Mixing components without checking compatibility, which CDC links to leaks and breaks in the system.
- Using one valve type interchangeably. CDC notes mechanical valves carry an increased infection risk compared with some split septum valves.
FAQ
What is a saline lock used for?
It keeps IV access open between doses without a continuous fluid infusion, replacing tubing and a fluid bag, as described in the 1994 prehospital study.
How often should the connector be changed?
CDC’s 2011 guideline says no more frequently than every 72 hours, or according to the manufacturer’s recommendations.
Is a saline lock the same as a saline flush?
No. The flush is the saline used with the lock; see what a saline flush is.
Sources
- CDC/HICPAC, Guidelines for the Prevention of Intravascular Catheter-Related Infections (2011, updated 2017); full-text PDF; checked 2026-11-03.
- Carducci and Stein, “Intravenous Maintenance with a Saline Lock Intermittent Infusion Device in the Prehospital Environment,” Prehospital and Disaster Medicine 9(1), 67-70, 1994; checked 2026-11-03.
