Eight resuscitator bags were connected to an oxygen source with up to 15 liters per minute (LPM) oxygen flowing and were tested by manually squeezing an 800-ml tidal volume ten times into a test apparatus that measured the oxygen concentration delivered from the bags. Then the bags were tested for valve function on conscious volunteers. The Laerdal, Air Viva, and Hope bag with Blount adapter delivered high oxygen concentrations, and all were improved over earlier models. The Air Shields Ambu with the new E2 valve was found mechanically superior to the older Ambu with sliding disk assembly, but maximum oxygen delivery capability had dropped steeply from the older model. The Drager, Drager with Frumin valve, Pulmonator, and Air Bird delivered insufficient oxygen concentrations (less than 60%) for hospital use.
Steinbach et al. (Wed,) studied this question.