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Abstract
Objective During interhospital transfer, critically ill neonates frequently require mechanical ventilation and are exposed to physical forces related to movement of the ambulance. In an observational study, we investigated acceleration during emergency transfers and if they result from changes in ambulance speed and direction or from vibration due to road conditions. We also studied how these forces impact on performance of the fabian+nCPAP evolution neonatal ventilator and on patient-ventilator interactions.
Methods We downloaded ventilator parameters at 125 Hz and acceleration data at 100 Hz sampling rates, respectively, during the emergency transfer of 109 infants. Study subjects included term, preterm and extremely preterm infants. We computationally analysed the magnitude, direction and frequency of ambulance acceleration. We also analysed maintenance and variability of ventilator parameters and the shape of pressure-volume loops.
Results While acceleration was <1 m/s2 most of the time, most babies were occasionally exposed to accelerations>5 m/s2. Vibration was responsible for most of the acceleration, rather than speed change or vehicle turning. There was no significant difference between periods of high or low vibration in ventilation parameters, their variability and how well targeted parameters were kept close to their target. Speed change or vehicle turning did not affect ventilator parameters or performance. However, during periods of intense vibration, pressure-volume ventilator loops became significantly more irregular.
Conclusions Infants are exposed to significant acceleration and vibration during emergency transport. While these forces do not interfere with overall maintenance of ventilator parameters, they make the pressure-volume loops more irregular.
- Emergency Care
- Intensive Care Units, Neonatal
- Neonatology
- Respiratory Medicine
- Technology
Data availability statement
Data are available on reasonable request. The Jupyter notebooks containing and explaining all the computer (python) code used for data processing and analysis can be viewed on GitHub code repository at https://github.com/belteki/ambulance_acceleration. Raw ventilator and accelerometer data are available on request.
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Data availability statement
Data are available on reasonable request. The Jupyter notebooks containing and explaining all the computer (python) code used for data processing and analysis can be viewed on GitHub code repository at https://github.com/belteki/ambulance_acceleration. Raw ventilator and accelerometer data are available on request.
Footnotes
Twitter @gbelteki
Contributors GB designed the study, wrote the computer programs to analyse ventilator data and performed the data analysis. LL, AS and ZS performed the transfers and collected clinical data. DC wrote some of the computer programs required for data analysis. GB is reponsible for the overall content of the paper as the guarantor. All authors revised and approved the final manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests GB is a consultant to Vyaire Medical (Mettawa, IL, USA) and Dräger Medical (Lübeck, Germany). Vyaire Medical did not participate in this research and did not provide any payment for it.
Provenance and peer review Not commissioned; externally peer reviewed.
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