Respiratory and Subjective Effects of Inhalation Valve Obstruction in the Flight Mask

Area of Science:

• Aerospace Medicine
• Human Factors Engineering
• Physiology

Background:

• Tactical aircrew experience physiological and cognitive impairment during flight.
• A proposed cause is respiratory disruption due to flight mask valve obstructions.
• This study examines the role of inhalation valve obstructions in flight events.

Purpose of the Study:

• To investigate if flight mask inhalation valve obstructions contribute to physiological events in the cockpit.
• To assess the impact of mask obstructions on respiration, symptoms, and cognitive performance.

Main Methods:

• Utilized a hypobaric chamber to simulate flight conditions.
• Compared a normal flight mask with a modified mask featuring inhalation valve obstructions.
• Measured respiratory behavior, subjective symptoms, and cognitive performance in 16 active-duty participants.

Main Results:

• Modified masks significantly altered gas pressures and flow, impacting respiratory behavior, especially during vocalization.
• Increased frequency of reported symptoms was observed with the modified mask.
• No significant differences in symptom severity or cognitive performance were found between masks.

Conclusions:

• Obstructions in the flight mask inhalation valve are a plausible factor in reported in-flight physiological events.
• Findings suggest that mask design and maintenance are critical for aircrew well-being.