What Researchers Did
Researchers tested how a Monaghan 225 ventilator performed inside a hyperbaric chamber at pressures up to 6 atmospheres absolute (ATA).
What They Found
The ventilator's delivered tidal volume remained consistent regardless of ambient pressure. However, the ventilatory rate decreased exponentially, reaching 45% of its normal rate at 6 ATA. After modifications, the rate at 6 ATA improved to 72% of the 1 ATA value, and essential functions like synchronized intermittent mandatory ventilation worked well. The maximum minute ventilation dropped from 48 L/min at 1 ATA to 18 L/min at 6 ATA.
Canadian Relevance
While this study was not conducted by Canadian authors or in Canada, it addresses the critical function of ventilators during hyperbaric oxygen therapy. This is relevant for Canadian patients undergoing HBOT for Health Canada-recognized indications such as decompression sickness or carbon monoxide poisoning, should they require ventilatory support.
Study Limitations
This study evaluated a specific ventilator model from 1986, and its findings may not fully apply to newer, more advanced hyperbaric ventilator technologies available today.