Effect of topical alkane vapocoolant spray on pain with intravenous cannulation in patients in emergency departments: Randomised double blind placebo controlled trial

Abstract

Objective: To assess the efficacy, acceptability, and safety of a topical alkane vapocoolant in reducing pain during intravenous cannulation in adults. Design: Randomised double blind placebo controlled trial. Setting: Emergency department of a metropolitan teaching hospital. Participants: 201 adult patients (54% male), mean (SD) age 58.2 (19.5) years, who required intravenous cannulation. Interventions: Less than 15 seconds before cannulation, the skin area was sprayed with either water (control, n=98) or vapocoolant (intervention, n=103), from a distance of 12 cm for 2 seconds. The intervention spray was a blend of propane, butane, and pentane. Main outcome measures: Pain with cannulation and discomfort with spray, measured with a 100 mm visual analogue scale. Results: Groups did not differ significantly in age, sex, indication for or site of cannulation, cannula size, or who cannulated the patient (P>0.05). Median (interquartile range) pain scores for cannulation in the control and intervention groups were 36 (19-51) and 12 (5-40) mm, respectively (P<0.001), and 59 (60%) and 33 (32%) reported pain scores ≥30 mm (P<0.001). Scores for spray discomfort also differed significantly (P<0.001) because of skewing to the right within the intervention group. The median discomfort scores, however, were 0 mm in both groups. Success rates for first cannulation attempt did not differ between groups (P=0.39). Thirty four (39%) and 62 (62%) patients said they would choose the spray they received for analgesia in the future (P=0.002). At follow-up at five days, two patients in the intervention group reported transient skin redness. Conclusions: Topical alkane vapocoolant spray is effective, acceptable, and safe in reducing pain with peripheral intravenous cannulation in adults in the emergency department. Trial registration: Australian Clinical Trials ACTRN12607000470493.