The resistance of Entonox valves.
D000769:Anesthesia, Inhalation / Q000295:instrumentation*; D000773:Anesthesia, Obstetrical; D005260:Female; D006801:Humans; D009609:Nitrous Oxide; D011247:Pregnancy; D011312:Pressure; D012122:Ventilators, Mechanical / Q000295:instrumentation*
D009609:Nitrous Oxide