Temperature, humidity and mucus flow in the intubated trachea.

Mucus flow rates were measured in the intact trachea of anaesthetized dogs, using a radioactive tracer technique. Measurements were made before intubation, and after intubation at inspired air temperatures of 32, 37 and 42°C, with a constant inspired water vapour content of 33 mg/1.; and again at each temperature with a relative humidity of 75%. No significant difference in mucus flow rate was found under any of these conditions.