Do term newborns respond similarly to different painful procedures?

Although many methods for pain assessment in newborns are available, none of them are widely accepted. Our aim was to answer the question: do newborns respond similarly to different painful procedures?

Sixty term newborns were involved in non-randomized prospective study. They were classified into 2 groups: Group A (n=30) who needed intubation and Group B (n=30) who necessitated umbilical vein catheterization. Close observation prior to and 10 minutes after the painful procedures was performed for recording of physiological and behavioral indicators. Plasma renin activity (PRA) was measured before and 10 minutes after the painful procedures.

There was statistically significant difference between the 2 groups as regards physiological and hormonal responses to pain (P<0.05). Apart from palmar sweating and crying, there was no significant difference in behavioral response (P>0.05). The median pre- and post-intubation levels of PRA were 3.04 and 12.05 ng/ml/hour, respectively. There was significant (P<0.001) increase of PRA after intubation. On the other hand, the median pre- and post-catheterization levels of PRA were 5.21 and 9.19 ng/ml/hour, respectively. There was significant (P<0.001) increase of PRA after umbilical vein catheterization. We found that PRA was the only indicator of pain in group A (P=0.047). On the other hand, we did not find any indicator of pain in group B.

We concluded that full-term newborns vary in their physiological and hormonal responses to different painful procedures but their behavioral response is the same.