The functional deadspace of needle-free injection ports.

This study examined six needle-free injection ports comprising three taps (Sorenson Intralock, Top type L, Viggo Connecta), a one-way valve (Braun RV 1000) and two cannulae with integral injection ports (Vasofix, Venflon 2) with regard to deadspace, protection against blood spillage, and potential difficulties in use. A conventional bung (Baxter), requiring needle use for drug administration, was included for comparison. Where necessary, ports were combined with cannulae in order to simulate clinical practice and allow fair comparison with the Vasofix and Venflon cannulae. Total deadspace was then calculated by filling with normal saline and measuring weight increase. Deadspace (0.10 to 0.43 ml) varied with injection port type and cannula size. Such volumes can contain significant amounts of drug and may be hazardous if not flushed after injection. Only the Vasofix and Venflon Cannulae and the Braun RV1000 protected adequately against blood spillage. Costs varied widely (A$0.19 to A$2.20 excluding cannula). The Vasofix and Venflon 2 cannulae were found to be nearest the ideal.