Anaesthesia, 1979, Volume 34, pages 882-884

A P P A R A T U S

The Valved-Y-Cardiff Connector (V.Y.C. Con)

It may be convenient to connect two infusions to the same cannula through a Y-connector when administering two fluids. When one of the infu- sion sets is at a higher pressure (either because the reservoir is at a higher level or because it is pressurised) and the cannula becomes blocked, then one fluid could flow up the other infusion set. I f that fluid were to contain a powerful drug, a catecholamine or a narcotic, when the cannula is subsequently unblocked a bolus sufficient to result in a dangerous overdose could then be delivered accidentally. The disposable valved Y-connector described here (Fig. 1) has been designed to eliminate that possibility. It is supplied in a sealed pack after sterilisation by ethylene oxide.

Description One limb of the connector is an open tube, while the other is fitted with a tap containing a rubber flap which acts as a one-way valve (Fig. 2). Both are fitted with female Luer lock connections and the delivery end has a male Luer-lock con- nection. The infusion containing the drug must be connected to the open limb, while the other infusion is connected to the limb which is fitted with the tap. The handle of the tap is triangular shaped and the apex indicates the position of the valve. It can be set as shown in Fig. 3.

(i) To allow free flow with the valve out of action. Fig. 1. The Valved-Y-Cardiff-Connector.

M. Rosen, FFARCS, Consultant Anaesthetist, B. Williams, HNC, Senior Technician. Correspondence should be sent to Dr Rosen, Department of Anaesthetics, University Hospital of Wales, Heath Park, Cardiff CF4 4XW.

882 ooO3-2409/79/looO-0882 $02.00 0 1979 Blackwell Scientific Publications

The valved- Y-Curdif connector 883

Fig. 2. Diagram of the Valved-Y-Cardiff-Connector.

(ii) To prevent flow from the infusion set connected to the valve limb although allowing backflow into it.

(iii) To allow flow from the infusion set connected to the valve limb and prevent back- flow into it.

When the tap is turned to position (iii) then the infusion attached to the other limb cannot pass in a retrograde fashion if the drug infusion set is pressurised. The pressure can then only be exerted through the cannula and the likeli- hood of blockage by blood clot is considerably reduced. The resistance characteristics of the tap in positions (i) and (iii) have been measured.

Method

A valved-Y-connector was attached to the outlet of a standard Baxter drip set, connected to a large water reservoir. The tap was turned to each position (i) and (iii) and the time for 200 ml of water to flow into a measuring cylinder was measured when the surface of the water in the reservoir was 50, 100 and 150 cm above the

( 1 ) ( 1 1 ) ( 1 1 1 )

Fig. 3. Direction of main flow (+) and retrograde flow (--- +) with different position of tap.

outlet of the valved Y-connector. The measure- ments were then repeated without the connector in position. This provided a pressure range from 5 to 15 kPa which corresponds to the range of pressure difference encountered in practice between the reservoir of an infusion set and a patient’s venous system. Each measurement was repeated three times, a t each pressure. Three new Y-connectors were tested.

Six new Y-connectors were tested for effective- ness in preventing back-flow when the tap was turned to position (iii). The outlet of the Y- connector was attached to the top of a tube, the bottom of which was dipped below water in a small jar. With the open limb of the Y-connector sealed and the valve tap turned to position (i) (valve out of use), the pressure in the jar was increased until the water rose through the tube and the valved limb of the Y-connector into a 1-ml syringe barrel connected to the inlet. This iiitial pressure in the jar and the water level in the syringe were noted. The valved tap was then turned to position (iii), the pressure in the jar was increased to 3 kPa and the level of the water in the syringe noted after 10 min. This experiment was repeated with pressures of 6 and 9 kPa in the jar.

Results

There was little difference in the flow through any of the Y-connectors tested under the same conditions (Fig. 4). The mean flow without a Y- connector was 207 ml/min at a pressure of 5 kPa and 500 ml/min at a pressure of 15 kPa. With a Y-connector with its tap turned t o posi- tion (iii) the mean flow was 64 ml/niin (s.d. I .94) at a pressure of 5 kPa and 212 mlirnin (s.d. 2.86) at a pressure of 15 kPa. With the tap in position

884 M. Rosen and B. Williams

500 r - 400 - 5

5 300 - .

3 0

B 200 - G

100 -

I 0 5 10

2 15

Pressure d i f fe rence between reservoir and outlet (kPo1

Fig. 4. The flow of water through the Valved-Y- Cardiff-Connector related to the pressure difference between the reservoir and the outlet of the connector. (a) Without Y connector, (b) tap in position (i), i.e. free flow through tap, (c) tap in position (iii), i.e. flow

through valve.

(i) the mean flow increased and ranged from 148 ml/min at a pressure of 5 kPa to 383 ml/min at a pressure of 15 kPa. Five Y-connectors showed no back-flow and one leaked 1 ml in 10 min at a pressure of 9 kPa.

Discussion

The danger of overdose attributable to the simultaneous use of two infusions through one cannula can be largely avoided by using this valved-Y-connector. The valve would not interfere with daily infusion requirements or even fairly fast flow but if necessary it can easily be switched off or removed from the circuit.

Summary

A disposable Y-connector for use when two infusions are connected to the same cannula has been tested. The connector incorporates a valved tap in one limb which prevents retrograde flow into the infusion connected to that limb.

Key words

EQUIPMENT; intravenous infusions, valves.

Acknowledgment

Several Y-connectors for test have been supplied by Messrs Vygon (U.K.) Ltd of Uxbridge, M iddlesex.