Preliminary evaluation of a prototype tube-valve-mask ventilator for emergency artificial ventilation

The objective was to design a prototype tube-valve-mask ventilator that would permit relatively inexperienced operators to provide adequate emergency artificial ventilation, namely, adequate ventilatory volumes and a high oxygen and low carbon dioxide delivery. The tube-valve-mask ventilator is powered by the exhaled air of the operator and uses a tube to act as an oxygen reservoir (1,300 mL) that is filled between breaths. Mouth-to-mouth breathing was the standard against which the tube-valve-mask ventilator and the other accepted methods of mouth-to-mask and bag-valve-mask were assessed. Comparison studies were conducted during simulated two-person CPR using a training mannikin equipped to measure ventilation volume and delivered oxygen and carbon dioxide concentrations. Seventeen volunteer first-year nursing students were used as operators. The order in which the pairs of operators performed each of the techniques was randomized. The ventilation volume and the percentage of oxygen and carbon dioxide delivered by each technique were as follows (mean ± SD): Mouth-to mouth (760 ± 290 mL, 17 ± 1% O 2, 3.4 ± 0.4% CO 2), mouth-to-mask (910 ± 350 mL, 41 ± 8% O 2, 2.5 ± 0.4% C0 2), bag-valve-(soft) mask (550 ± 230 mL, 94 ± 3% O 2, 0.03 ± 0.02% CO 2), bag-valve-(rigid) mask (560 ± 300 mL, 96 ± 3% O 2, 0.03 ± 0.02% CO 2), and tube-valve-mask (860 ± 290 mL, 91 ± 7% O 2, 0.2 ± 0.2% CO 2). In the hands of relatively inexperienced operators, mouth-to-mouth, mouth-to-mask, and tube-valve-mask techniques provide adequate ventilation volumes to a mannikin. This was not the case with the bag-valve-mask systems (800 mL; P = .05 by t test). Of the systems that provide adequateventilation volume, the tube-valve-mask appears. superior in that higher oxygen and lower carbon dioxide concentrations can also be obtained ( P = .05 by paired t test).