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Essential equipment: Taps, hubs and connectors


Taps

Purpose

Just as with domestic taps, these are turned on and off to control flow and there is even a mixer version.

Description

Only two types of tap are of importance but there are some important caveats:

Two-way taps

These taps have two positions – on and off – they are often used on the end of connecting tubes.

Two-way taps come in two styles:

  • Rotating valve: this is a standard form of tap and is almost ubiquitous.

  • Sliding switch: this allows the tap to be turned on and off very quickly; this is particularly useful for CO 2 angiography.

Three-way taps

Most vascular sheaths have a three-way tap attached to the side-arm. It will come as no surprise that three-way taps have an additional side-port. The tap acts as a selector allowing you to choose which of the ports are connected. The long arm of the tap is ‘off’, simply point it towards the port you wish to close.

Three-way taps permit:

  • Air bubbles to be flushed out when a syringe is connected. This is the primary function of the tap on the side-arm of a vascular sheath.

  • Two syringes to be attached together. This allows one to be used as a reservoir, e.g. during particulate or liquid embolization.

  • The system to be calibrated to atmospheric pressure in pressure measurement circuits.

  • Connection of pressurized saline flushing systems ( Fig. 15.1 ).

    Fig. 15.1, ‘Traffic light’ system.

Measurements

These do not strictly apply but not all taps were created equal and there are two important considerations.

Fitting

Slip fit is fine for the ward but has no place in interventional radiology; only use taps with Luer lock fittings.

Pressure

Most taps will be fine connected to a pressurized bag of saline used to flush a coaxial system. However, not all taps have been designed to allow high-pressure, high-flow rate injection using a pump injector. If you want to avoid an exploding tap treating everyone to a contrast shower, make sure you ask for a high-pressure tap.

Tip

The same caveat applies to connecting tubes. If you are using a pump injector for arteriography you need a high-pressure connector and tap capable of allowing the planned pressure and flow rates.

Know what to ask for

In general, stick to the simplest tap which will do the job. If you are working in arteries or intend to use a high-flow pump injection then make sure that you have a suitable high-pressure tap.

Know how to use it

Just make sure you know the on and off positions. The commonest mistakes are leaving a tap open and finding a puddle of blood, trying to inject against a closed tap or injecting out of the side-port of a three-way tap.

Haemostatic seals

Purpose

These are seals designed to:

  • Prevent blood and other fluid leaking from catheters and coaxial systems, such as sheaths, while you are thinking about something else.

  • Allow the introduction of catheters and wires.

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