Performance of the Uni-Vent Eagle™ Model 754 ventilator under hyperbaric conditions

Area of Science:

• Biomedical Engineering
• Critical Care Medicine
• Hyperbaric Medicine

Background:

• Critically ill patients may require mechanical ventilation during hyperbaric oxygen therapy.
• Older mechanical ventilators, like the Uni-Vent Eagle model 754, are still in use and may pose risks under hyperbaric conditions.
• Concerns exist regarding potential oxygen leaks and fire hazards with pre-existing ventilators in hyperbaric environments.

Purpose of the Study:

• To evaluate the performance and safety of the Uni-Vent Eagle model 754 ventilator under hyperbaric conditions.
• To investigate the risk of oxygen leaks within the ventilator housing at increased atmospheric pressures.
• To determine the impact of hyperbaric conditions on delivered tidal volumes and respiratory mechanics.

Main Methods:

• The Uni-Vent Eagle model 754 was tested at 1.0, 2.4, and 2.8 atmospheres absolute (ATA) in assist control mode.
• A Michigan test lung was used with varying tidal volumes and respiratory rates.
• Delivered volumes, peak pressures, and oxygen percentages in the chamber and ventilator housing were recorded.

Main Results:

• The ventilator delivered approximately 25% less tidal volume at 2.4 and 2.8 ATA compared to 1.0 ATA.
• Breath stacking observed at high respiratory rates was reduced at hyperbaric pressures.
• No increase in oxygen levels was detected within the ventilator housing at 2.4 and 2.8 ATA.

Conclusions:

• The Uni-Vent Eagle model 754 demonstrates safe and effective performance under hyperbaric conditions.
• Hyperbaric conditions cause a depth-dependent decrease in delivered tidal volumes.
• Accurate programming of the Uni-Vent Eagle model 754 requires spirometry to compensate for reduced delivered volumes at depth.