A novel flow partition device for spirometry during large animal anaesthesia

Area of Science:

• Veterinary Anesthesia
• Respiratory Monitoring
• Medical Device Engineering

Background:

• Accurate respiratory monitoring is crucial in large animal anesthesia.
• Existing monitoring systems may not be readily adaptable or cost-effective for equine use.
• Human spirometry sensors offer potential for adaptation due to their availability and established performance.

Purpose of the Study:

• To describe and evaluate a novel flow partitioning device (FPD) for adapting human spirometry sensors for large animal anesthesia monitoring.
• To assess the performance characteristics of the FPD, including pressure drop, resistance, and dead space.
• To compare the FPD's performance against an existing device (Horse-lite).

Main Methods:

• An in-vitro study was conducted to test the FPD.
• The FPD utilizes adapters to split airflow evenly into four parallel tubes, each with a D-lite spirometry sensor.
• Performance was evaluated across a range of flows (100–700 L/min), measuring pressure, flow, resistance, and dead space.

Main Results:

• At 700 L/min, the FPD exhibited a pressure drop of 13.5 cm H₂O, resistance of 1.17 cm H₂O·s/L, and dead space of 182 mL.
• These values compare to 2.8 cm H₂O, 0.24 cm H₂O·s/L, and 54 mL for the Horse-lite.
• Flow partitioning accuracy was confirmed, with limits of agreement of 4.2% (inspiratory) and 7.1% (expiratory).

Conclusions:

• The FPD is an affordable device enabling the use of human spirometry sensors in large animals.
• An increase in total resistance and dead space must be considered when using the FPD.
• The device shows potential utility for monitoring during equine anesthesia.