Intramuscular vaccination is among the most common source of iatrogenic pain in infants. Vapocoolant sprays are rapid-acting alternative to topical anesthetics. They provide transient anesthesia via evaporation induced skin cooling, and reduce pain due to vaccine injection in children and adults. The objective was to compare the synergistic analgesic effect of eutectic mixture of local anesthetics (EMLA) with breastfeeding (EB group) and vapocoolant spay with breastfeeding (VB group) to that of only breastfeeding (BO group) during whole cell diptheria, pertussis and tetanus (wDPT) vaccination.
A double blind randomized controlled trial was done to include infants up to 3 months of age who came for their first wDPT vaccination. The primary outcome variable was the duration of cry after vaccination. Secondary outcome variables were Modified Facial Coding Score, Neonatal Infant Pain Scale and latency of onset of cry.
Of the 201 eligible participants, 111 babies were excluded and remaining 90 babies were randomized into three groups of thirty each. The groups did not differ significantly in baseline characteristics. Median (interquartile range, IQR) of duration of cry was lesser [35.86 (21.07-107.75) seconds] in babies receiving EMLA cream with breast feeding (EB group) and in babies receiving vapocoolant spray with breast feeding (VB group) [32.58 (21.25-106.21) seconds] as compared to babies receiving only breast feeding (BO group) [67.5 (27.6-180) seconds] (P=0.147). Difference in median (IQR) of latency of cry was not statistically significant. Modified Facial Coding Score and Neonatal Infant Pain Scale at 1 minute and 3 minutes was significantly lower in the EB and VB group, as compared to the BO group (P<0.05).
Addition of topical EMLA application or vapocoolant spray to breastfeeding during wDPT vaccination does not reduce duration of cry in infants up to 3 months of age. However, they are able to show reduction in pain score and further studies are warranted to assess their efficacy as pain relief measures in infants and children.