Chest
Volume 122, Issue 3, September 2002, Pages 955-959
Journal home page for Chest

Clinical Investigations
COPD
Comparison of Sputum Induction Using High-Output and Low-Output Ultrasonic Nebulizers in Normal Subjects and Patients With COPD

https://doi.org/10.1378/chest.122.3.955Get rights and content

Study objectives

Induced sputum is used to investigate pulmonary diseases. Low-output ultrasonic nebulizers have become available and have potential advantages over high-output nebulizers. We hypothesized that a low-output nebulizer would give comparable results to a high-output nebulizer, with an acceptable safety profile.

Design

Randomized, crossover study.

Setting

University teaching hospital.

Participants

Ten normal subjects and 10 patients with COPD.

Interventions

Participants attended for sputum induction on two occasions in random order using low-output and high-output nebulizers.

Measurements and results

Lung function and oxygen saturation were measured during sputum induction, and tolerability of the procedure was assessed. Cell counts, interleukin 8, and neutrophil elastase were measured in sputum. Use of the high-output nebulizer resulted in a greater FEV1 (mean ± SEM, 0.29 ± 0.04 L vs 0.21 ± 0.04 L; p = 0.04) and percentage drop in FEV1 (25.8 ± 2.6% vs 19.5 ± 2.9%, respectively; p = 0.02) compared with the low-output nebulizer in patients with COPD. There was a shorter tolerated nebulization time with the high-output nebulizer compared with the low-output nebulizer: 12.7 ± 2.0 min vs 16.5 ± 1.8 min, respectively (p = 0.02). Modified Borg scores were lower with the low-output nebulizer than the high-output nebulizer in normal subjects: median, 0 (interquartile range [IQR], 0 to 1) vs median, 1.5 (IQR, 0 to 2), respectively (p = 0.05). There were no differences in cell counts and soluble markers of inflammation.

Conclusions

The low-output ultrasonic nebulizer is comparable to high-output nebulizer for cellular and soluble markers of inflammation, results in a smaller reduction in FEV1, is better tolerated, and is a suitable tool for investigating airway inflammation in patients with COPD.

Section snippets

Normal Subjects

Ten normal nonsmoking subjects (5 men) with no recent serious concomitant illnesses, history of atopy or asthma, or history of childhood chest disease were recruited: mean ± SEM age, 28 ± 1 years; FEV1, 3.65 ± 0.29 L; and FEV1 percent of predicted, 98.1 ± 3.2%.

Patients With COPD

Ten patients (7 men) with stable COPD attending the Belfast City Hospital Respiratory Medicine clinics were also recruited: mean age, 63 ± 3 years; FEV1, 1.08 ± 0.14 L; FEV1 percent predicted, 40.7 ± 4.2%; pulse oximetric saturation, 91.4

Results

Ten normal subjects and 10 patients with COPD were studied, and all successfully produced sputum. Nebulization was stopped due to a > 20% drop in FEV1 in three patients with COPD using the low-output nebulizer and seven patients with COPD using the high-output nebulizer. The high-output nebulizer produced a significantly larger drop in FEV1 (mean, 0.29 ± 0.04 L vs 0.21 ± 0.04 L, p = 0.04) and percentage drop in FEV1 (mean, 25.8 ± 2.6% vs 19.5 ± 2.9%, p = 0.02) compared with the low-output

Discussion

This study demonstrates that a low-output ultrasonic nebulizer can produce adequate and comparable samples to conventional, high-output ultrasonic nebulizers. It has a superior safety profile and better patient tolerance when compared to the high-output nebulizer.

The smaller fall in FEV1 and longer nebulization time suggests that the low-output nebulizer is more acceptable for use in patients with COPD. However, even with the low-output nebulizer, a > 20% fall in FEV1 occurred in three

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    Work performed at Department of Clinical Biochemistry, Queen's University of Belfast and Department of Respiratory Medicine, Belfast City Hospital.

    Research supported by a grant from the Northern Ireland Chest, Heart, and Stroke Association.

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