Ethyl Chloride Vapocoolant as Anesthesia for Arterial Punctures

Ethyl chloride vapocoolant sprays provide transient skin anesthesia within seconds of application. The current investigation aim is to compare the effect of ethyl chloride based vapocoolant spray to placebo in reducing pain associated with arterial puncture for gasometry determinations. The investigators will conduce a double-blind randomized placebo-controlled trial at Emergency Department. We will enroll patients who come to Emergency Department who need an arterial gasometry determination. Patients will be randomized to intervention-group (ethyl chloride vapocoolant sprays will be usad before arterial puncture) or to placebo-group (alcohol spray as placebo will be used before arterial puncture.) and after the puncture they will rate their pain using a 10 points visual analogue scale.