A High-Value, Low-Cost Bubble Continuous Positive Airway Pressure System for Low-Resource Settings: Technical Assessment and Initial Case Reports

Acute respiratory infections are the leading cause of global child mortality. In the developing world, nasal oxygen therapy is often the only treatment option for babies who are suffering from respiratory distress. Without the added pressure of bubble Continuous Positive Airway Pressure (bCPAP) which helps maintain alveoli open, babies struggle to breathe and can suffer serious complications, and frequently death. A stand-alone bCPAP device can cost $6,000, too expensive for most developing world hospitals. Here, we describe the design and technical evaluation of a new, rugged bCPAP system that can be made in small volume for a cost-of-goods of approximately$350. Moreover, because of its simple designﾗconsumergrade pumps, medical tubing, and regulators—it requires only the simple replacement of a ,$1 diaphragm approximately every 2 years for maintenance. The low-cost bCPAP device delivers pressure and flow equivalent to those of a reference bCPAP system used in the developed world. We describe the initial clinical cases of a child with bronchiolitis and a neonate with respiratory distress who were treated successfully with the new bCPAP device

Short term evaluation of respiratory effort by premature infants supported with bubble nasal continuous airway pressure using Seattle-PAP and a standard bubble device

Background Almost one million prematurely born infants die annually from respiratory insufficiency, pre- dominantly in countries with limited access to respiratory support for neonates. The primary hypothesis tested in the present study was that a modified device for bubble nasal continu- ous positive airway pressure (Bn-CPAP) would provide lower work of spontaneous breath- ing, estimated by esophageal pressure-rate products. Methods Infants born \u3c32 weeks gestation and stable on Bn-CPAP with FiO2 \u3c0.30 were studied within 72 h following delivery. Esophageal pressures during spontaneous breathing were measured during 2 h on standard Bn-CPAP, then 2 h with Bn-CPAP using a modified bubble device presently termed Seattle-PAP, which produces a different pattern of pressure fluctu- ations and which provided greater respiratory support in preclinical studies, then 2 h on stan- dard Bn-CPAP. Results All 40 infants enrolled completed the study and follow-up through 36 wks post menstrual age or hospital discharge, whichever came first. No infants were on supplemental oxygen at completion of follow-up. No infants developed pneumothoraces or nasal trauma, and no adverse events attributed to the study were observed. Pressure-rate products on the two devices were not different, but effort of breathing, assessed by areas under esophageal pressure-time curves, was lower with Seattle-PAP than with standard Bn-CPAP. Conclusion Use of Seattle-PAP to implement Bn-CPAP lowers the effort of breathing exerted even by relatively healthy spontaneously breathing premature neonates. Whether the lower effort of breathing observed with Seattle-PAP translates to improvements in neonatal mortality or morbidity will need to be determined by studies in appropriate patient populations

Vital signs for 6-month old patient with bronchiolitis (a) and a neonate with respiratory distress (b) immediately before and after initiation of bCPAP.

<p>(A) Time course immediately before treatment (large symbols) and after initiation of therapy (small symbols). The patient received CPAP treatment with gradually decreasing oxygen flow for 4 days, was then transitioned to nasal oxygen, and finally transitioned to room air. The patient was discharged on day 6. (B) Time course immediately before treatment (large symbols) and after initiation of therapy (small symbols). The patient received CPAP treatment for 3.5 days. The fraction of oxygen was gradually decreased to room air during the first 2 ½ days.</p

bCPAP device operating specifications.

<p>bCPAP device operating specifications.</p

Comparison of reference standard and low-cost bCPAP output pressure under different flow and pressure settings.

<p>Each bCPAP system was assembled and nasal prong pressure was measured for 60 seconds of operation and mean pressures were calculated; results were then averaged for 10 independent trials of each system. (A) The mean pressure (mid-point of bar) and peak low and high pressures at a flow rate of 7 L/min at varying pressure settings. (B) The mean pressure (mid-point of bar) and peak low and high pressures at a pressure of 6 cm H₂O and varying flow rates.</p

Block diagram and photograph of bCPAP system.

<p>The system consists of: (1) an adjustable flow generator; (2) a pressure-regulated delivery system; and (3) a patient interface. Flow is generated by two air pumps that can be blended with oxygen from a tank or concentrator. The total flow rate and fraction of oxygen delivered are controlled by two flow regulators. The output of the flow generator is connected to the pressure-regulated delivery system. Pressure is controlled by submerging a pressure control tube in a column of water; the mean pressure in the system is determined by the height of the water column. The patient interface is also connected to the pressure control tube, ensuring that the pressure in the patient interface and the pressure control tube are equivalent. The pressurized air mix is delivered to the patient's nostrils via a set of binasal prongs terminated at the distal end.</p

Pressure vs. time at the nasal prongs for two bCPAP devices.

<p>(Left) a reference standard bCPAP device used clinically in the US and (Right) the low-cost bCPAP device. Dotted lines show the mean and average peak pressures, averaged across 60 seconds of data collection. The pressure waveforms of the two devices are similar, indicating delivery of equivalent therapeutic pressure. In both devices, the mean pressure is controlled by adjusting the height of water in the pressure control tube, and the high frequency oscillations about the mean are associated with the formation of bubbles at the distal tip of the pressure control tube. There were no statistically significant differences between the pressures generated by the two devices (Student t-test, p<0.01).</p

Short term evaluation of respiratory effort by premature infants supported with bubble nasal continuous airway pressure using Seattle-PAP and a standard bubble device

<div><p>Background</p><p>Almost one million prematurely born infants die annually from respiratory insufficiency, predominantly in countries with limited access to respiratory support for neonates. The primary hypothesis tested in the present study was that a modified device for bubble nasal continuous positive airway pressure (Bn-CPAP) would provide lower work of spontaneous breathing, estimated by esophageal pressure-rate products.</p><p>Methods</p><p>Infants born <32 weeks gestation and stable on Bn-CPAP with FiO₂ <0.30 were studied within 72 h following delivery. Esophageal pressures during spontaneous breathing were measured during 2 h on standard Bn-CPAP, then 2 h with Bn-CPAP using a modified bubble device presently termed Seattle-PAP, which produces a different pattern of pressure fluctuations and which provided greater respiratory support in preclinical studies, then 2 h on standard Bn-CPAP.</p><p>Results</p><p>All 40 infants enrolled completed the study and follow-up through 36 wks post menstrual age or hospital discharge, whichever came first. No infants were on supplemental oxygen at completion of follow-up. No infants developed pneumothoraces or nasal trauma, and no adverse events attributed to the study were observed. Pressure-rate products on the two devices were not different, but effort of breathing, assessed by areas under esophageal pressure-time curves, was lower with Seattle-PAP than with standard Bn-CPAP.</p><p>Conclusion</p><p>Use of Seattle-PAP to implement Bn-CPAP lowers the effort of breathing exerted even by relatively healthy spontaneously breathing premature neonates. Whether the lower effort of breathing observed with Seattle-PAP translates to improvements in neonatal mortality or morbidity will need to be determined by studies in appropriate patient populations.</p></div

GEE model fit of PRP, ΔP_es, RR, and AUCs, on time and epoch.

<p>GEE model fit of PRP, ΔP_es, RR, and AUCs, on time and epoch.</p

CONSORT flow chart for enrollment and study of infants.

<p>Due to the repeated measures design of the present study, enrollment of consecutive infants was neither intended nor attempted. Of the 42 sets of parents approached for enrollment, 40 agreed, and all of these infants completed the study, including follow-up to 36 weeks or discharge from hospital. Thus, follow-up and other data are comprehensive for all 40 of these infants. However, technical issues, many arising from the physical activities, such as body motion, swallowing, and similar actions of the unsedated infants interfering with efforts to record P_es, limited acquisition of interpretable data in 13 of the 40 infants.</p