The pressor response to venous cannulation: attenuation by prior infiltration with local anaesthetic.

We have compared the cardiovascular response to insertion of an 18-gauge venous cannula in 40 healthy patients. In 20 of the patients, cannulation was preceded by infiltration of local anaesthetic. Both rate-pressure product and mean arterial pressure increased significantly (P < 0.01) compared with baseline when no local infiltration was used, but there was no significant change from baseline when infiltration with local anaesthetic preceded cannulation. We conclude that there is a significant pressor response to venous cannulation which is obtunded by prior infiltration with local anaesthetic. We recommend, therefore, that s.c. injection of lignocaine should be considered before insertion of an i.v. cannula, especially in the high risk patient.