(I-353) Testing A Low-Cost Bubble CPAP for Neonatal Infants in Low to Middle Income Countries

Introduction:: Annually, over 2 million preterm births globally result in about 60-95% of neonatal infants requiring respiratory support [1]. A prominently used neonatal respiratory supportive device is a ventilator derived continuous positive airway pressure (CPAP) device, but increased survival rates are seen with its successor, the bubble CPAP [2]. A bubble CPAP device provides a humidified air-oxygen mixture and an oscillating gas pressure to keep the alveoli of the lungs expanded during breathing. Due to their high expenses, neither option is available globally. Therefore, a low-cost bubble CPAP device has been developed for low to middle income countries to increase accessibility. As the device has been prototyped and iterated, testing based on design specifications is necessary prior to clinical trials. The goal of testing is ensuring that the device meets international medical device standards for efficiency, usability, accuracy, and safety.

Materials and Methods:: The full setup of the bubble CPAP device was used with the addition of an oxygen tank and air pump, monitored with MATLAB codes to generate graphs. In evaluating efficiency and usability, 60 cm, 80 cm, and 100 cm tubing lengths were tested with the device for three hours to determine the option that would allow the quickest increase of inspiratory air temperature. An important feature of the device that requires accuracy is the air oxygen mixing system, which was tested by comparing measurements against a custom designed chart. This chart lists flowrate combinations which provide a specified oxygen concentration within the inspired air. Meanwhile, international medical device standards from ISO 80601-2-74:2017 were used to evaluate the device’s safety [3]. To identify potential hazards, variability tests were conducted, during which thermal overshoots were detected as air flow rates increased. To further understand this phenomenon, this test was repeated 20 times on multiple devices by increasing the air flow rate in increments of one to six liter per minute (lpm). The time taken for the inspiratory air temperature to return to a desired 35°C was recorded.

Results, Conclusions, and Discussions:: The results of efficiency and usability testing using the specified tubing lengths show in Figure 1 that a 60 cm length tubing allowed the patient’s inspiratory air to reach the desired temperature in the quickest time (60 cm = 42 minutes, 80 cm = 48 minutes, 100 cm = 70 minutes). However, the 80 cm length tubing was deemed the best option as it allows the clinicians flexibility with the device’s placement relative to the patient, improving efficiency and usability. The accuracy testing of the air-oxygen chart shows that the device produces accurate oxygen concentrations within 5% oxygen of the calculated values with a mean difference of 2.2%. This supports the device’s design specification that accurate air-oxygen blends are produced consistently. Following the ISO 80601-2-74:2017 Standard for safety, the inspiratory air temperature cannot exceed 43°C for over 2 minutes [3]. With results compiled in Figure 2, the device returns to the desired temperature of 35°C from above 42°C within an average of 11 minutes (standard deviation = 4.46), which does not meet the safety standard. However, Figure 3 shows that one liter per minute (lpm) increments did not cause overshoots on average. Using this as a limit until encoded safety features or design iterations are added, the device meets the required safety standard. The present study provides evidence of the device’s adherence to the international medical device standards of efficiency, usability, accuracy, and safety. After further design iterations are completed to meet various international medical device standards, the device will be move into approval for clinical trials which will further assess its ability to be used globally for neonatal infants requiring respiratory support in low to middle income countries.

Acknowledgements: : Assisted by D. Amagyei, S. Bordom, P. Ramaswamy.
This work was supported by the Kern Family Foundation eREU grant EEC2150076.

References: :
[1] Chan, Kyra Y. Y. et al. “Respiratory Support of the Preterm Neonate: Lessons About Ventilation-Induced Brain Injury from Large Animal Models.”

[2] Bahman-Bijari B, Malekiyan A, Niknafs P, Baneshi MR. “Bubble-CPAP vs. Ventilatory-CPAP in Preterm Infants with Respiratory Distress.”

[3] International Organization for Standardization. (2017). Medical Electrical Equipment Part 2-74: Particular Requirements for Basic Safety and Essential Performance of Respiratory Humidifying Equipment. (ISO 80601-2-74:2017).