title: Upper limits of resistance of apparatus used for inhalation analgesia during labour: response of mothers.
mesh_terms: D000403:Airway Resistance; D000769:Anesthesia, Inhalation / Q000295:instrumentation*; D000773:Anesthesia, Obstetrical; D005260:Female; D006801:Humans; D008365:Manometry; D009609:Nitrous Oxide / Q000008:administration & dosage; D010100:Oxygen / Q000008:administration & dosage; D011247:Pregnancy
chemical_list: D009609:Nitrous Oxide; D010100:Oxygen