Chest
Volume 116, Issue 4, October 1999, Pages 941-945
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Clinical Investigations
ASTHMA
Effect of Sputum Induction on Spirometric Measurements and Arterial Oxygen Saturation in Asthmatic patients, Smokers, and Healthy Subjects

https://doi.org/10.1378/chest.116.4.941Get rights and content

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 healthy subjects.

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%).

Conclusions

This 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.

Section snippets

Subjects

We selected a group of 14 patients (age range, 18 to 49 years) with bronchial asthma as defined by the American Thoracic Society.13 We included lifetime-nonsmoking patients with no respiratory infections or spontaneous asthma relapses in the 4 weeks before the study. Respiratory symptoms were controlled with inhaledβ 2-agonists on a daily basis or as required. Patients requiring steroids or sodium cromoglycate were excluded. Baseline FEV1 had to be > 60% of the predicted value. The presence of

Results

Subject characteristics are shown in Table 1. Asthmatic subjects showed significantly lower baseline FEV1 values than subjects with a history of smoking or healthy subjects (p < 0.05), and no differences were found among the three groups with respect to gender and age. During the sputum induction procedure, the most commonly reported side effects included slight nausea with retching and an unpleasant salty taste. No subject developed side effects sufficiently severe to require premature

Discussion

This study has shown a significant fall in Sao2 during the stated sputum-induction procedure for subjects with bronchial asthma, subjects with a history of smoking, and healthy subjects. Additionally, the study has confirmed that sputum production induced by inhaling hypertonic saline solution is well tolerated in subjects with mild-to-moderate bronchial asthma, subjects with a history of smoking, and healthy subjects.

In accordance with the safety protocol proposed by Wong and Fahy,9 we

References (21)

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