A one-way (non-rebreathing) valve suitable for use in gas analysis of exercising horses.

The study discusses the invention and evaluation of a one-way valve for respiratory gas separation during horse exercises. The valve is designed to be low in weight, offer low resistance, easy in construction, withstand high flow rates, and remain unaffected by vibration and positional changes.

Introduction to the Study

• This research focuses on the design and efficacy of a one-way (non-rebreathing) valve meant for analyzing gas exchange in exercising horses.
• There is a necessity in respiratory function analysis to separate the air inhaled from what is exhaled, which comes with certain challenges.
• Preexisting valves can induce abnormalities in respiration, and their function depends on the properties of the device and the demands of the respiratory system.
• Current one-way valves for large mammals like horses and cattle are limited, hence a new respiratory valve was needed.

The Design of the Valve

• The valve must be easily constructed, lightweight, have low resistance even at the high flow rates during vigorous exercise, and its operation should not be influenced by changing positions or vibrations.
• The valves were made from 7mm thick and 160mm diameter plexiglass plates. These plates were drilled using a commercially available valve reamer to create valve seats.
• 12 valves, originally made for human use, were fitted into each plexiglass plate to form multi-element assemblies after their anchoring points were removed.
• These assemblies were then installed into a polyethylene facemask that featured two ports opening directly in front of a horse’s nares (nostrils).

Testing and Evaluation of the Valve

• The other two ports were positioned laterally to the nostrils and perpendicular to the other ports.
• The plates were arranged in the desired direction to manage air flow and fixed in place using spring steel retaining rings.
• The valves’ flow-resistive characteristics were analyzed by measuring differential pressures across the plate at identified flow rates. These rates were measured by a device called a rotameter.
• The study concluded that the valve resistance was around 0.1 kPa for flows up to 4000 L/min, the relationship defined between flow rate and differential pressure.