A closed-loop reduced oxygen breathing device for inducing hypoxia in humans

Area of Science:

• Physiology
• Aerospace Medicine
• Medical Devices

Background:

• Hypoxia presents risks in aerospace and diving, and in various clinical conditions.
• Current research and training for hypoxia often require large, costly hypobaric chambers.

Purpose of the Study:

• To describe and evaluate a compact, economical, closed-loop rebreather-type reduced-oxygen breathing device (ROBD) for inducing hypoxia in humans.
• To assess the efficacy of the ROBD as a practical tool for hypoxia research and training.

Main Methods:

• Four healthy subjects (student Naval flight surgeons) participated.
• Subjects breathed normoxic air (21% O2) at baseline, followed by hypoxic air (approx. 10% O2, simulating 5,486 m) for 30 minutes.
• Physiological parameters including oxygen saturation (SpO2), blood pressure, cardiac output, and systemic vascular resistance were monitored.

Main Results:

• Hypoxic exposure significantly reduced fraction of inspired oxygen (FiO2) and SpO2 compared to baseline and recovery.
• Heart rate and cardiac output increased, while systemic vascular resistance decreased during hypoxia.
• The ROBD successfully maintained the target hypoxic conditions.

Conclusions:

• The closed-loop ROBD is a potentially valuable tool for inducing acute hypoxia.
• This device can be utilized for both training and research purposes in healthy and clinical populations.
• The ROBD offers a more accessible and economical alternative to traditional hypobaric chambers.