Development of a Re-Breathing System for Mechanical Ventilators
Abstract
Introduction: Maximizing the capabilities of available low flow oxygen is key to providing adequate oxygen to prevent/treat hypoxemia and conserve oxygen. We designed a closed-circuit system which allows rebreathing of gases while scrubbing carbon dioxide (CO2) in conjunction with portable mechanical ventilators in a bench model. Methods: We evaluated the system using two portable mechanical ventilators currently deployed by the DoD: Zoll 731 and AutoMedx SAVe II over a range of ventilator settings and lung models, using 1 and 3 L/min low flow oxygen into a reservoir bag. We measured peak inspired oxygen concentration (FiO2), CO2 absorbent life, gas temperature and humidity, and the effect of airway suctioning and ventilator disconnection on FiO2 on ground and at altitude. Results: FiO2 was greater than or equal 0.9 across all ventilator settings and altitudes using both oxygen flows. CO2 absorbent life was greater than 7 hours. Airway humidity range was 87 percent-97 percent. Mean airway temperature was 25.4+- 0.5 deg C. Ten second suctioning reduced FiO2 22-48 percent. Thirty second ventilator disconnect reduced FiO2 29-63 percent depending on oxygen flow used. Conclusion: Use of a rebreathing system with mechanical ventilation has the potential for oxygen conservation but requires diligent monitoring of inspired FiO2 and CO2 to avoid untoward consequences.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2023
- Accession Number
- AD1201857
Entities
People
- Richard D Branson
- Thomas C Blakeman
Organizations
- University of Cincinnati