Inhalation of carbon dioxide mixtures for sensorineural deafness. Evaluation of a rebreathing method.
A laboratory study in 11 healthy subjects was conducted to evaluate the performance of a rebreathing device as a means of raising the effective carbon dioxide level in the inspiratory mixture. In all subjects, there was a sustained rise in end-tidal carbon dioxide levels and a transient rise in end-tidal nitrogen tensions associated with an equivalent fall in end-tidal oxygen levels. Although the rise in end-tidal carbon dioxide tensions was variable, the mean elevation for the 11 subjects (from 36 to 43 mm Hg) was not equivalent to elevations reported to follow inhalation of 5% carbon dioxide mixtures. Nevertheless, the volume of the device was sufficient to cause a marked depression of the end-tidal oxygen level (to 67 mm Hg) in one subject. Despite the simplicity and cost-effectiveness of the rebreathing method, it cannot be recommended in the treatment of sudden or fluctuant sensorineural deafness.
D002245:Carbon Dioxide / Q000008:administration & dosage* / Q000032:analysis; D007758:Ear, Inner / Q000098:blood supply; D005069:Evaluation Studies as Topic; D005260:Female; D034381:Hearing Loss / Q000628:therapy*; D006801:Humans; D008297:Male; D009584:Nitrogen / Q000032:analysis; D010100:Oxygen / Q000032:analysis; D012039:Regional Blood Flow; D012138:Respiratory Therapy / Q000295:instrumentation / Q000379:methods*; D013990:Tidal Volume
D002245:Carbon Dioxide; D009584:Nitrogen; D010100:Oxygen