Neurophysiological and behavioral measures of pain during neonatal hip examination

The aim of this study was to test the hypothesis that neonatal hip examination causes pain in newborns. Pain assessment using instruments such as the Premature Infant Pain Profile-Revised (PIPP-R) scale is recommended, but recently physiological and neurophysiological measures, for example, near-infrared spectroscopy (NIRS) and galvanic skin response (GSR), have been used as well.

Heart auscultation and hip examination were performed, and the response of the newborn was registered by NIRS optodes, GSR electrodes, and a pulse oximeter probe attached to the infant. The face of the newborn was filmed. Heart auscultation was used as a nonpainful reference.

The pain scores for hip examination were higher than for the heart auscultation. Near-infrared spectroscopy showed a significant higher increase from baseline in oxygenated hemoglobin (HbO₂) on both sides of the cortex at hip examination compared with at heart auscultation (P = .011 and P = .017). Mean PIPP-R scores for the hip examination compared with heart auscultation increased from 3.0 to 8.1 (P = .000). The GSR analyses of hip examination compared with heart auscultation showed a significant increase in area under small peaks during the hip examination (P = .016), however, not when measured in peaks per second (P = .104). Interrater reliability was calculated for the NIRS interpretations, with an intraclass correlation coefficient (ICC) range of 0.93-1.0 (P = .000).

Pain in newborns can have negative consequences, and pain prevention and treatment are therefore important. We conclude that neonatal hip examinations are painful and that the pain should be treated, for example, with oral sweet solution. This is a change from present routines during neonatal hip examination and is hoped to lead to a change in national guidelines.