Anaesthesia for arterial puncture in the emergency department: a randomized trial of subcutaneous lidocaine, ethyl chloride or nothing

Abstract

To determine whether the use of ethyl chloride and subcutaneous lidocaine are associated with a reduction in pain during arterial blood sampling compared with using no local anaesthesia. Patients over the age of 16 years and who required arterial blood sampling as part of their on-going emergency department management were randomly allocated to one of three groups. Group A received routine skin preparation before arterial puncture (AP); group B received 0.5 ml of 2% lidocaine 2 min before AP; and group C received ethyl chloride immediately before AP. Pain was measured using 100-mm visual analogue scale. Two urban emergency departments. Fifty-four patients were recruited. Those receiving lidocaine before AP had lower pain scores [10.2 mm, 95% confidence interval (CI): 4.8-16.3 mm] compared with the use of ethyl chloride (23.9 mm, 95% CI: 12.4-35.5 mm) and nothing (23.4 mm, 95% CI: 11.7-35.0 mm). Lidocaine was more painful to administer (22.0 mm, 95% CI: 10.9-33.7 mm) compared with ethyl chloride (12.9 mm, 95% CI: 5.5-20.3 mm). Ethyl chloride is not an effective local anaesthetic agent for AP. When the pain of local anaesthetic administration is taken into account the benefit of subcutaneous lidocaine for single AP is limited.