Background Newborns frequently need to be transferred to level-III-centers shortly after birth. Especially in very low birth weight infants, these postnatal transports are correlated with increased risk for intraventricular hemorrhage. Despite specifically designed incubators, infants are exposed to a considerable amount of mechanical vibrations (MV) that are presumed to be one of the major risk factors.
Aims The objective was to investigate the extent of MV and the frequency spectrum occurring during neonatal transport.
Methods Two types of incubators (ITI-5400 (INC1), Air-Shields-Isolette-TI-500 (INC2), both DRÄGER, Lübeck, Germany) were tested during simulated neonatal transport by ambulance vehicle on various road types. MV were recorded by highly-sensitive accelerometers (LIS331DL, STMicroelectronics, Geneva, Switzerland) and analyzed by using Fast-Fourier-Transform and Continuous-Wavelet-Transform.
Results MV occurring in INC1 during transport had peak accelerations up to 0.91 g (8.93 m/s2) and a dominant frequency range of 10–14 Hertz. Measurements with INC2 showed significantly higher peak accelerations with values up to 1.60 g (15.70 m/s2) and further a distinct peak in the frequency spectrum at approximately 15 Hertz. Total detected MV within the investigated frequency band of 1–50 Hertz were up to 8 times higher in INC2 compared to INC1.
Conclusions We were able to demonstrate that during neonatal transport newborns might be exposed to almost twofold gravitational acceleration, whereby accelerations and vibration frequencies differed distinctly between incubators. On the basis of these data implementation of vibration analysis in approval procedures of transport incubators has to be considered.