Local Anaesthetic Infiltration Prior to Arterial Puncture for Blood Gas Analysis: A Survey of Current Practice and a Randomised Double-Blind Placebo Controlled Trial

BACKGROUND: Infiltration with local anaesthetic (LA) is recommended before arterial puncture (AP) for blood gas analysis. A telephone survey of 100 junior hospital doctors established that 84% never used LA; the reason for this cited by 47% of doctors was that they considered the injection to be as painful as AP itself. We therefore undertook a randomised double blind placebo controlled trial to establish whether the recommendation for LA is justified. METHODS: Patients undergoing AP were randomly allocated to one of three groups before arterial stab: A — Infiltration with 2% lignocaine; B — Infiltration with normal saline; C — No infiltration. Patient and doctor then rated the discomfort of the procedure. RESULTS: Both patients and doctors rated the pain of AP less when LA was used. Infiltration with LA was no more painful than with placebo. AP was no more difficult following LA as assessed by passes made, times skin broken and the doctor's rating of the procedure. CONCLUSION: This study supports the recommendation that LA should be infiltrated before radial artery puncture is performed. The belief that the use of LA makes the procedure more difficult and is as painful as arterial puncture should be dispelled.