Do we necessarily need local anaesthetics for venous cannulation? A comparison of different cannula sizes.

BACKGROUND AND

OBJECTIVE

This randomized, prospective study was performed to evaluate the efficacy of a subcutaneous local anaesthetic infiltration prior to venepuncture using different cannula sizes.

METHODS

Three-hundred-and-one patients were included in the study, 150 received mepivacaine 1% (0.25 mL) subcutaneously, 151 were cannulated without local analgesia. Patients were further allocated to one of five cannula size groups (standard wire gauge (G)): 20-, 18-, 17-, 16- and 14-G. They were asked to quantify the pain experienced using a four-point rating scale.

RESULTS

In the group without local anaesthetics, 28.8% complained about pain compared to 12% receiving local analgesia. The incidence of pain for 14-G (10%) and 16-G (12.9%) cannulae was significantly reduced in the local analgesia group (P < 0.01) compared to no local analgesia (77.4% and 45.1%). Other cannula sizes showed no difference in pain whether using local analgesia or not.

CONCLUSIONS

Patients profit from a subcutaneous infiltration with mepivacaine 1% prior to intravenous cathetherization only when cannulae of size > or = 16-G are inserted.