Fellow Children's Hospital of Eastern Ontario Children's Hospital of Eastern Ontario Ottawa, Ontario, Canada
Background: Each year, thousands of newborns are transported by air or ground ambulance to receive specialized medical care. For neurologically immature and physiologically compromised infants, especially preterm infants, the noise and vibration exposure during transport are high despite preventative measures and may be an important contributor to brain injury risk.
Objective: To develop a new tool to investigate vibrations during neonatal transport and mitigation strategies.
Design/Methods: Proof of concept study including 3 steps: 1.Characterization of the vibrations during transport. Accelerometer sensors placed on different layers of the Neonatal Patient Transport System NPTS (neonate manikin, mattress, incubator, deck, stretcher, and vehicle floor) with a variety of ambulance on road tests performed to capture data. 2. Experimentation. A shaker table was used to develop a standardized test environment. Vibration testing was performed, with the entire NPTS mounted on the shaker table. 3. Mitigation. Shaker table tests were repeated using different configurations of mattress and harness types on manikins with different bodyweights.
Results: Characterization. Road transport exposed the manikin’s head to vibrations that exceeded adult standards. Examining the frequency spectra of the accelerometer signals across different layers of the NPTS suggests that the interfaces stretcher/vehicle floor and incubator/deck may be critical for intervention to mitigate the vibrations, as they showed the highest gain in vibration power. Experimentation. Comparison between the on-road and shaker table tests showed that the shaker table was able to reproduce on-road transportation with acceptable fidelity. The shaker table setup can serve as a standardized environment to explore the impact of several NPTS design variables on vibrations transmitted to the patient. Mitigations. Different mattresses were shown to influence the vibrations experienced by the manikin. The head restraint harness type showed an amplitude reduction of the peak frequency component for all experiment types for most mattress types compared to the standard 5-points harness. Conclusion(s): Our study demonstrated that i) vibrations during neonatal transport can exceed adult standards, ii) acceptable fidelity simulation of road condition can be achieved using a shaker system, iii) different mattress and harness combinations demonstrated varying vibration transmission and iv) most effective approach for vibration mitigation should consider the whole NTPS instead of focusing solely on the isolette.
Neonatal Patient Transport System (NTPS) overview.
Top: Instrumented NTPS in ambulance during preliminary road test. Accelerometers circled in yellow (top-left, bottom-right).
Bottom: Power spectral density (PSD) plot (frequency spectra) showing vibrations at vehicle floor and a mannequin’s head. Amplification of vibrations visible at 9 Hz.
NRC Flight research Lab Shaker System.
Power spectral density (PSD) plots of Neonatal Patient Transport System (NPTS) layers for shaker test compared to on-road test.
Authors/Institutions: Laurent Renesme, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada; Fadwa Darwaish, Carleton University, Ottawa, Ontario, Canada; Kimberley J. Greenwood, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada; Cheryl Aubertin, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada; James Green, Carleton University, Ottawa, Ontario, Canada; Adrian D. Chan, Carleton University, Ottawa, Ontario, Canada; Robert Langlois, Carleton University, Ottawa, Ontario, Canada; Stephanie Redpath, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada