Better tools needed to measure pain in infants
24 June 2008
A study of prematurely born infants has revealed that the tools doctors currently use to assess whether a baby is in pain may underestimate how much pain the infant is feeling. Researchers led by Dr Rebeccah Slater of UCL (University College London) compared cortical pain responses (those processed by the brain) with pain assessment tools based on physiological and behavioural measurements for example changes in heart rate or facial expression. The research is published in the journal Public Library of Science Medicine.
Twelve infants were included in the study and they were observed a total of 33 times when undergoing a heel lance to collect a blood sample, a painful event. The team studied the relationship between brain activity and pain as indicated by a clinical pain score called the premature infant pain profile (PIPP) that uses factors such as change in facial expression and heart rate to signal the presence of pain.
They found that changes in brain activity correlated to the PIPP scores. And that these changes were more strongly linked to the behavioural components like facial expression than to physiological factors like heart rate. They also observed no change in facial expression in 13 of the 33 test occasions though during 10 of these tests there was a brain response indicating pain.
Dr Rebeccah Slater, lead author from UCL Neuroscience, Physiology and Pharmacology explains:
“Although our study was small, it does raise concerns about the tools normally used by doctors to establish whether a baby is feeling pain. Infants may appear to be pain free, but may, according to brain activity measurements, still be experiencing pain. Pain assessment based on behavioural tools alone should be interpreted with caution as they could under estimate the total pain response.’’
Evidence from other studies suggests that inadequate pain management in infants may have adverse effects. Repetitive pain in preterm infants has been associated with attention deficit disorder, learning disorders and behavioural problems in later childhood so learning how best to manage pain would be of benefit to infants.
“It would be interesting to explore whether measures of brain activity could complement current methods for measuring pain in infants.’’ Dr Slater concluded.
The study was funded by the Medical Research Council, Wellcome Trust and children’s medical research charity SPARKS.
Original research paper: How well do clinical pain assessment tools reflect pain in infants? by Rebeccah Slater et al is published in Public Library of Science Medicine.
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