Being exposed to recordings of their mothers’ voices limited pain preterm infants experienced while undergoing heel lance procedures, according to a study conducted in an Italian neonatal intensive care unit (NICU). Recordings were of the infants’ mothers singing lullabies or saying nursery rhymes and were made and administered at sound levels that are considered safe within the NICU.
The 40 infant participants, born at 26 to 34 weeks of gestation, were divided into 2 groups. Infants in 1 group listened to recordings of their mothers’ voices during routine heel lances for blood collection (intervention group) and the other group did not (control group). Infants in the intervention group underwent 10-minute sessions of being exposed to their mothers’ voices twice a day for 3 consecutive days before the heel lance as well as for 10 minutes before the procedure started until 20 minutes after it ended. Infants in the control group were not exposed to their mothers’ voices. Both groups received routine care.
Investigators evaluated infants’ pain by monitoring vital parameters 4 times: 10 minutes before starting the procedure, when the infants were pricked, and 10 minutes and 20 minutes after the procedure ended. Pain was assessed with the Premature Infant Pain Profile (PIPP) scale.
Although both groups showed a marked increase in PIPP scores when the heel lance was performed, infants in the intervention group had significantly lower scores. Similarly, although both groups showed a marked decrease in oxygen saturation at the time of the heel prick, values of the infants in the intervention group were significantly higher than those of infants in the control group. In both groups, PIPP scores declined and oxygen saturation values rose after the heel prick, returning to baseline 10 minutes later. The 2 groups did not differ in heart rate, respiratory rate, and arterial or diastolic blood pressure (Chirico G, et al. Acta Paediatr. 2017;106:1564-1568).
Thoughts from Dr Burke
To the extent that the PIPP scale is subjective, the investigators’ knowledge of the infants’ assignment to treatment or the control group may have changed the outcome for that measure. However, I can think of no way that oxygen saturation would be influenced by the lack of blinding. Is a recording of any mother effective, or does each baby respond best to his or her own mother? And wouldn’t it be interesting to know if the mother’s anxiety and perception of her child’s pain is altered by participation in this practice?