Background: Sputum production induced by inhalation of
hypertonic saline solution has been proposed as a technique to
collect secretions and inflammatory cells from the airways of
subjects with bronchial asthma or with a history of smoking. The aim of
this study was to determine the effect of a sputum induction procedure
on spirometric results and arterial oxygen saturation
(Sao2) in asthmatic patients, smokers, and
Methods: We recruited 14 subjects
suffering from asthma (11 men and 3 women; age range, 18 to 49 years),
14 subjects with a history of smoking (5 men and 9 women; age range, 23
to 64 years), and 9 healthy volunteers (7 men and 2 women; age range,
28 to 54 years). To obtain a sample of induced sputum, all subjects
inhaled a mist of 3% hypertonic saline solution nebulized for 5 min
and repeated the cycle no more than four times. Asthmatic patients were
pretreated with 200 μg salbutamol (inhaled). During sputum induction,
the transcutaneous Sao2 was continuously
measured and baseline, fall, and the differences between baseline and
fall Sao2 were recorded. Additionally, we
measured the duration of mild desaturation (change in
Sao2, < 4%) and of marked desaturation
(change in Sao2, > 5%) in each subject.
Finally, baseline FEV1 and changes in FEV1 as a
percentage of baseline values were recorded in all subjects.
Results: We found that baseline and fall
Sao2 values for the three groups were similar.
However, in each group a significant mean change in
Sao2 was evident during sputum production
(asthmatic patients, 6.0%; smokers, 5.3%; healthy subjects, 6.0%).
Moreover, the mean durations of mild desaturation were 7 min, 21 s
in asthma patients; 8 min, 24 s in smokers; and 7 min, 16 s
in healthy subjects. Similarly, the durations of marked desaturation
were 1 min, 25 s in asthmatic patients, 1 min, 19 s in
smokers, and 1 min, 21 s in healthy subjects. The mean (± SD)
fall in FEV1 was not statistically different among the
three groups (asthmatic patients, 1.36 ± 5.6%; smokers,
7.58 ± 11.76%; and healthy subjects, 0.05 ± 9.6%).
However, one smoker did experience excessive bronchoconstriction (fall
in FEV1, > 20%).
study demonstrated a significant and comparable fall in
Sao2 during sputum induction by inhalation of
hypertonic saline solution in asthmatic patients, smokers, and
healthy subjects. The results suggest that subjects who are hypoxemic
before sputum induction require Sao2 monitoring
during the procedure.