Measuring vibrations of transport stress in premature and newborn infants during incubator transport

Despite increasing numbers of centers for perinatology, transportation of newborns and premature infants can not totally be avoided for several obvious reasons. The following investigations were carried out as part of our quality control measures of the established neonatal transportation system, and were aimed on the optimization of a new neonatal transportation equipment resulting in reduction of transportation stress caused by acceleration forces. The new system investigated consisted of a Volkswagen type T4 equipped with a Dräger incubator type 5400, which was mounted on a pneumatic patient lift. We measured acceleration forces in three axes (expressed as K-Wert) as well as over a spectrum of frequencies (1-80 Hz). Measurements were taken at different points of the transportation unit during simulated transports driving a predetermined route. After obtaining informed consent of the parents, one actual transport of a newborn was used for an additional point measurement at the newborn's head. The mean K-Wert was decreased by about 50% in the vertical axis between the chassis of the car and the incubator by activating the pneumatic patient lift. Without activating the lift the K-Wert increased by about 20% between the car's chassis and the incubator. The frequency analysis showed resonance effects between the different components of the system. However, by activating the patient lift, effective accelerations in the incubator were decreased to less than 0.1 m/s2 across the whole frequency spectrum evaluated. The single measurement at a newborn's head revealed similar acceleration forces at the head of the baby and under its head. Utilization of a pneumatic patient lift can reduce acceleration forces. However, our results show that each system (car, incubator, and its base) has to be investigated and optimized for this purpose as a unit. Optimization of the complete system is necessary not only before its primary use but also in regular intervals over the years. Sometimes, further improvements can be reached with minor modifications such as the exchange of worn out rubber buffers.