Analysis of sequential aliquots of hypertonic saline solution-induced sputum from clinically stable patients with cystic fibrosis.
OBJECTIVE
Sputum induction (SI) is a noninvasive tool for sampling inflamed airways. The purpose of this study was to determine the optimal duration of collection in patients with cystic fibrosis (CF). The hypothesis was that the duration of SI collection would quantitatively and qualitatively alter the content of the induced sputum.


METHODS
In 10 clinically stable patients with CF (mean +/- SD age, 28 +/- 7 years; mean FEV(1), 2.6 +/- 0.7 L), SI was performed with 3% hypertonic saline solution at five time points over 20 min.


RESULTS
SI was well tolerated, with an average maximum fall in FEV(1) of 7 +/- 7%. The sample volumes, urea concentrations, interleukin-8 concentrations, total cell counts, and nonsquamous cell counts remained constant (p > 0.05). The percentage of neutrophils decreased from 89 +/- 5% to 86 +/- 4% (p = 0.03), and the percentage of alveolar macrophages increased 5 +/- 2% to 8 +/- 4% (p < 0.01). The mean quantitative microbiological counts of nonmucoid Pseudomonas aeruginosa and Staphylococcus aureus decreased over the 20-min time period each by half a log (p = 0.05 and p < 0.01, respectively). Surfactant protein-A concentration increased from 1.6 +/- 0.3 to 2.4 +/- 0.4 ng/mL (log(10); p < 0.001).


CONCLUSIONS
We conclude that aliquots of induced sputum are similar in clinically stable patients with CF during 4-min intervals, although there is more alveolar sampling after 20 min. When induced-sputum samples are fractionated for research monitoring of inflammatory or microbiologic indexes, power calculations accounting for these variations over time are required.
Aitken
Moira L
ML
Department of Medicine, Division of Pulmonary and Critical Care, University of Washington, Seattle 98195, USA.
Greene
Kelly E
KE
Tonelli
Mark R
MR
Burns
Jane L
JL
Emerson
Julia C
JC
Goss
Christopher H
CH
Gibson
Ronald L
RL
D000328:Adult; D015415:Biomarkers; D002452:Cell Count; D015169:Colony Count, Microbial; D003550:Cystic Fibrosis / Q000175:diagnosis*; D005260:Female; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D008297:Male; D010865:Pilot Projects; D037661:Pulmonary Surfactant-Associated Proteins / Q000378:metabolism; D012044:Regression Analysis; D012462:Saline Solution, Hypertonic; D013048:Specimen Handling / Q000379:methods*; D013183:Sputum / Q000737:chemistry* / Q000166:cytology; D013997:Time Factors; D014508:Urea / Q000378:metabolism
D015415:Biomarkers; D016209:Interleukin-8; D037661:Pulmonary Surfactant-Associated Proteins; D012462:Saline Solution, Hypertonic; D014508:Urea