(H-286) Clinical evaluation of a novel, low-cost continuous respiratory rate and apnea monitor for newborns

Introduction:: Preterm birth interrupts physiological development, leaving newborns vulnerable to complications requiring respiratory rate (RR) monitoring. Complications include respiratory distress syndrome, a leading cause of death in preterm newborns, and apnea of prematurity, which affects 50% of preterm newborns and may be a presenting symptom of underlying conditions such as sepsis, hypoglycemia anemia, or seizures^1,2. When patient monitors are unavailable, the World Health Organization (WHO) recommends counting breaths for 60 seconds to measure neonatal RR³. In low-resource settings, patient monitors are often prohibitively expensive, and manual counting is impractical due to high nurse-to-patient ratios⁴. We developed a low-cost, continuous RR/apnea monitor for newborns in low-resource settings. The device detects breathing motion through two inertial measurement unit (IMU) sensors attached opposite the centerline of an abdominal belt. This pilot study clinically evaluates the device against reference visual counting and compares performance to existing patient monitors in Blantyre, Malawi and Houston, Texas, USA.


Materials and Methods:: Preterm newborns at risk for apnea or needing respiratory support at Queen Elizabeth Central Hospital (QECH) in Blantyre, Malawi, and Texas Children’s Hospital (TCH) in Houston, Texas, USA were enrolled for respiratory monitoring. Participants received continuous monitoring from the novel device in addition to standard of care monitoring (impedance pneumography, SpO2, electrocardiogram, RR, heart rate, temperature) from a patient monitor (IntelliVue MP30, Philips at QECH and GE Dash 4000, General Electric Company at TCH). Participants were video recorded by a webcam (WE800, Bonsaii at QECH and C925-E, Logitech at TCH) during monitoring. Video pixel block-matching in Matrix Laboratory (MATLAB, MathWorks) estimated inter-frame motion to automatically label participant activity state (at rest, motion) throughout monitoring. Researchers manually counted breaths using a custom video annotation GUI (graphical user interface) from one-minute, non-overlapping epochs randomly selected from at-rest data for RR accuracy analysis. In addition, inter-frame optical flow calculated over the participant’s abdomen in MATLAB automatically labelled epoch breaths for manual count comparison. Bland-Altman plots assessed inter-counter agreement as well as the novel device and patient monitor’s error from the reference standard of manual counting. Rice University Institutional Review Board (IRB), the College of Medicine Research and Ethics Committee in Malawi, and Baylor College of Medicine IRB approved this study.


Results, Conclusions, and Discussions:: Ten newborns at QECH averaging 33 weeks [32-34] gestational age and enrollment weight of 1563g [1030–2023g] were monitored for an average of 72 minutes [49-92min]. On average, subjects spent 50 min/hr [39-58min/hr] of monitoring time at rest with at-rest periods lasting 1.3±0.9 minutes. Total monitoring time was over 12 hours with just over 10 hours identified as at-rest. Ten epochs per subject, for a total of 100 epochs, were selected for reference counting and RR Bland-Altman analysis. Inter-counter agreement was -0.11 bpm with -2.45, +2.24 bpm 95% limits of agreement (LOA). Novel device RR bias from manual counting RR was -0.03 bpm [-3.58, +3.52 bpm LOA] and patient monitor bias was +1.08 bpm [-10.82, +8.66 bpm LOA].

Seven newborns at TCH averaging 32.6 weeks [30.3-36.1] gestational age and enrollment weight of 1402g [1200-1610g] were monitored for an average of 117 minutes [80-145min]. Enrollment at TCH and data analysis are ongoing, and Figure 1 summarizes only newborns enrolled at QECH. Preliminary RR accuracy analysis shows our novel device falls within the optimal accuracy specification (±2 bpm) of the UNICEF and NEST360 Target Product Profile (TPP) for a RR/apnea monitor for low-resource settings⁵. Accuracy validation with QECH/TCH training and testing datasets is ongoing as part of a larger aim to report device accuracy and alignment with TPP standards.

Clinical studies are ongoing with the goal of device commercialization. The implementation of a low-cost respiratory rate and apnea monitor would decrease the burden on nurses, improve neonatal monitoring, and reduce mortality and morbidity in sick and preterm newborns in low-resource settings.


Acknowledgements (Optional): : This work was supported by generous commitments from the John D. & Catherine T. MacArthur Foundation, the Bill & Melinda Gates Foundation, the Children’s Investment Fund Foundation, The ELMA Philanthropies, the Lemelson Foundation, the Sall Family Foundation, the Ting Tsung and Wei Fond Chao Foundation, and individual donors to NEST360.


References (Optional): : [1] Muhe, L.M., McClure, E.M., Nigussie, A.K., Mekasha, A., Worku, B., Worku, A., et al. (2019). Major causes of death in preterm infants in selected hospitals in Ethiopia (SIP): a prospective, cross-sectional, observational study. Lancet Glob Health. 7(8), 1130–1138. https://doi: 10.1016/S2214-109X(19)30220-7

[2] Zhao, J., Gonzalez F., & Mu D. (2011). Apnea of Prematurity: from Cause to Treatment. European Journal of Pediatrics, 170(9), 1097–1105. https://doi:10.1007/s00431-011-1409-6

[3] World Health Organization (WHO). (1990). ARI Programme for Control of Acute Respiratory Infections. Fourth Programme Report, 1988-1989. 7.

[4] Gathara, D., Serem, G., Murphy, G. A. V., Obengo, A., Tallam, E., Jackson, D., Brownie, S., & English, M. (2020). Missed nursing care in newborn units: a cross-sectional direct observational study. BMJ quality & safety, 29(1), 19–30. https://doi.org/10.1136/bmjqs-2019-009363

[5] Kirby, R. (2020). Respiratory rate/Apnea monitor. UNICEF & NEST360 Target product profiles for newborn care in low-resource settings, 1.0, 161-175.