External thermomechanical stimulation versus vapocoolant for adult venipuncture pain: pilot data on a novel device

Mechanoreceptor and noxious thermal inhibitory stimulation modulate pain conduction but have not been clinically tested in combination. Our objectives were to determine whether a vibrating cold device decreased adult venipuncture pain on a 10 cm visual analog scale more than no intervention, and compared with vapocoolant analgesia versus no intervention.

The design was a prospective randomized crossover clinical trial. Thirty healthy adult volunteers were randomized to the study device or vapocoolant intervention. One nurse attempted cannulation on both intervention and control hands with a 22 gauge intravenous catheter. Vapocoolant was applied to the cannulation site, or the device was applied 5 to 10 cm proximally throughout the intervention attempt. Visual analog scale assessed needle fear and the primary outcome of self-reported pain.

Sixteen device and 14 vapocoolant participants were included in this study. One participant felt discomfort from device prongs before the needle stick and was excluded. Compared with no intervention, the device reduced pain significantly (mean 9.9 mm, 95% confidence interval 0.82-19, P=0.035, SD 16) whereas vapocoolant did not (mean 7.9 mm, 95% confidence interval -1.8-17.7, P=0.1, SD 16.9). Mean pain reduction for device group participants was not significantly different from vapocoolant participants. Each 20 mm of prior anxiety increased the likelihood of intervention pain relief (odds ratio 2, P=0.043). One venipuncture failure occurred in the vapocoolant intervention.

The combination of cold and vibration gave significant venipuncture pain relief without affecting cannulation success. Interventions were more helpful for those with greater preprocedural fear. Larger sample sizes and a prongless device could better compare equivalence or superiority to existing pain relief modalities.