Published in:
01-07-2004 | Brief Report
Mucociliary function deteriorates in the clinical range of inspired air temperature and humidity
Published in: Intensive Care Medicine | Issue 7/2004
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Objective
To test whether a reduction in air temperature within the clinical range [37 °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 °C (100% RH) the tissue was either maintained with those settings (controls), or the air temperature reduced to 34 °C or 30 °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 °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 °C or 30 °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 °C, or even 34 °C, with 100% RH may not be sufficient to prevent epithelial damage occurring during 6 h exposure.