Feasibility of adding extraneous fresh gas flow (Heliox or Air) at an accessory fresh gas flow entry point in a fresh gas flow compensated anesthesia machine

Helium can be used as a constituent respiratory gas to decrease the Reynolds number and flow resistance of the gas mixture for patients with lower and upper airway obstruction during anesthesia. Anesthesia machines are generally not fitted for use of helium. This study investigated the feasibility of introducing heliox (80% helium, 20%oxygen mixture) into an anesthesia machine near the reservoir bag. There were no clinically important differences between the 2 gas entry points (for native versus accessory) at any fresh gas flow rate. Our results show that it is feasible to introduce heliox at an accessory gas entry point.