Role of OPRM1, clinical and anthropometric variants in neonatal pain reduction.

An increased awareness on neonatal pain-associated complications has led to the development of pain scales adequate to assess the level of pain experienced by newborns such as the ABC score. A commonly used analgesic procedure is to administer a 33% oral dextrose solution to newborns prior to the painful intervention. Although this procedure is very successful, not in all subjects it reaches complete efficacy. A possible explanation for the different response to the treatment could be genetic variability. We have investigated the genetic variability of the OPRM1 gene in 1077 newborns in relation to non-pharmacologic pain relief treatment. We observed that the procedure was successful in 966 individuals and there was no association between the genotypes and the analgesic efficacy when comparing individuals that had an ABC score = 0 and ABC score >0. However, considering only the individuals with ABC score>0, we found that the homozygous carriers of the G allele of the missense variant SNP rs1799971 (A118G) showed an interesting association with higher ABC score. We also observed that individuals fed with formula milk were more likely to not respond to the analgesic treatment compared to those that had been breastfed.

Skin conductance variations compared to ABC scale for pain evaluation in newborns.

OBJECTIVES: To validate spontaneous skin conductance variations as a specific reliable mean to measure pain in full-term healthy newborns during heel stick, comparing it with the ABC scale. To compare oral sucrose to wrapping effectiveness for non-pharmacological analgesia during the same procedure. METHOD: All recruited newborns (n = 158) underwent a heel stick for metabolic screening at 48 h of life with non-pharmacological analgesia by oral sucrose (group A) or wrapping (group B) according to randomization. Their pain was estimated by ABC scale score (standard method) and measured by skin conductance variations. RESULTS: A positive correlation was founded between peaks per sec measure and ABC score (rs = 0.303, p < 0.005). ABC score in group A was lower than in group B (p < 0.001). Difference in mean ABC score among newborn subgroups treated by different nurses was not statistically significant for wrapping while it was significant for sucrose (p = 0.001). CONCLUSIONS: Skin conductance measurement device is a reliable method to evaluate pain. Novel technological devices may be a useful support to clinical observation in this field. Oral sucrose is more effective than wrapping in reducing pain. Operators should be well periodically re-trained in performing non pharmacological analgesia during minor procedure on newborns.