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

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.