A technique for the simultaneous measurement of nasal and oral respiration.

A technique is developed which for the first time enables the direct and simultaneous measurement of inspired and expired air, both orally and nasally. The apparatus for such measurement consists of a Plexiglas chamber in which the subject's head is enclosed. Attached is a series of valves, flowmeters, differential air pressure transducers, and a physiography for the recording of respiratory activity. The apparatus used in data collection is described. The reliability of the instrument is established. The analysis of the physiographic record is explained and illustrated by data from six trials. The use of this technique to describe respiratory mode is discussed, together with indications for its future use in orthodontics and other research areas.