Influence of mist tent therapy on sputum viscosity and water content in cystic fibrosis.

The hypothesis that mist tent therapy decreases the viscosity of sputum by 
direct liquefaction of the sputum in the lower respiratory tract was 
tested in 6 patients with cystic fibrosis (CF). The first night 
all patients slept without the mist tent and the first morning 
sputum was collected for analysis. The following 2 nights patients were 
randomly allocated to a tent supplied by either a jet or 
ultrasonic nebulizer. The early morning sputum was analysed for volume, viscosity, 
water content, and DNA content, an index of purulence. There was 
no relation between sputum viscosity and DNA content, water content, or 
volume. Furthermore, there was no consistent relation between sputum viscosity or 
volume expectorated and the presence or absence of an 8-hour stay 
in the tent with either method of water nebulization. These results 
therefore suggest that mist therapy does not consistently influence sputum viscosity 
or volume in patients with CF. Above a sputum water content 
of 90%, further increases in water content do not influence viscosity. 
