Mucociliary function deteriorates in the clinical range of inspired air temperature and humidity

Intensive Care Med. 2004 Jul;30(7):1491-4. doi: 10.1007/s00134-004-2235-3. Epub 2004 Mar 16.


Objective: To test whether a reduction in air temperature within the clinical range [37 degrees C to 30, 100% relative humidity (RH)] altered mucus transport velocity (MTV) and ciliary beat frequency (CBF) in an in vitro ovine tracheal model.

Design: Controlled laboratory study.

Setting: University research laboratory.

Subjects: Farm-reared sheep.

Interventions: Tracheae were mounted flat in an organ bath. Krebs Henseleit bathed the serosal surface and air at 100% (RH) was passed over the mucosal surface at 4 l/min. Cilial beat frequency (CBF) was measured photo-electrically and mucus transport velocity (MTV) by timing movement. After 2 h at 37 degrees C (100% RH) the tissue was either maintained with those settings (controls), or the air temperature reduced to 34 degrees C or 30 degrees C. Tissue was taken for histology before and after each experiment.

Measurements and results: CBF was 19.8+/-2.7 beats/s and MTV 5.7+/-2.6 mm/min in tissue exposed to air at 37 degrees C. Cilial activity continued for up to 6 h in the controls but mucus transport was more fragile. Reduction of the air temperature to either 34 degrees C or 30 degrees C led to a decrease in both CBF and MTV and, frequently, total mucociliary failure. There was a reduction in epithelial mucous cell numbers in all preparations. Tissues exposed to low temperature had additional abnormal histology.

Conclusions: Delivery of inspired gas at 30 degrees C, or even 34 degrees C, with 100% RH may not be sufficient to prevent epithelial damage occurring during 6 h exposure.

Publication types

  • Comparative Study

MeSH terms

  • Air
  • Animals
  • Humidity
  • Mucociliary Clearance / physiology*
  • Respiratory Mucosa / metabolism
  • Respiratory Mucosa / physiology
  • Sheep
  • Temperature
  • Trachea / metabolism
  • Trachea / physiology*