Sound and vibration: effects on infants' heart rate and heart rate variability during neonatal transport

Aim: To measure the effect of sound and whole-body vibration on infants' heart rate and heart rate variability during ground and air ambulance transport.

Methods: Sixteen infants were transported by air ambulance with ground ambulance transport to and from the airports. Whole-body vibration and sound levels were recorded and heart parameters were obtained by ECG signal.

Results: Sound and whole-body vibration levels exceeded the recommended limits. Mean whole-body vibration and sound levels were 0.19 m/s(2) and 73 dBA, respectively. Higher whole-body vibration was associated with a lower heart rate (p < 0.05), and higher sound level was linked to a higher heart rate (p = 0.05). The heart rate variability was significantly higher at the end of the transport than at the beginning (p < 0.01). Poorer physiological status was associated with lower heart rate variability (p < 0.001) and a lower heart rate (p < 0.01). Infants wearing earmuffs had a lower heart rate (p < 0.05).

Conclusions: Sound and whole-body vibration during neonatal transport exceed recommended levels for adults, and sound seem to have a more stressful effect on the infant than vibrations. Infants should wear earmuffs during neonatal transport because of the stress-reducing effect.