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Effect of a Microaerosol Barrier Filter on the Measurement of Lung Function

journal contribution
posted on 2023-05-16, 16:59 authored by Johns, DP, Booth, H, Eugene WaltersEugene Walters
Study objective: A disposable barrier filter (Pall Biomedical, United Kingdom) was developed to prevent the contamination of lung function equipment in clinical use. The aims of this study were to examine its resistance characteristics and to determine the effect of the filter on clinical measurements of lung function. Measurements: Twenty-one randomly selected patients and four normal subjects had lung function measured with and without the filter between the mouth and measuring equipment. Measurements of ventilatory function were made with a pneumotachograph (Lilly; Hoechberg, Germany), total lung capacity and airway resistance by constant volume plethysmography, and diffusing capacity for carbon monoxide by the single breath method. Resistance was determined in five unused filters over the flow range 1 to 12 L/s and at a single flow rate (12 L/s) just after a normal subject expired 20 forced vital capacity (FVC) breaths through each of them. Results: The resistance (mean ± SD) of unused filters was 0.19±0.02 cm H 2 O/L/s at 1 L/s and increased linearly to 0.56 ± 0.02 cm H 2 O/L/s at 12 L/s. There was no significant increase in resistance after use. The addition of the filter to the breathing circuit caused statistically significant decreases in forced expiratory volume in 1 s (FEV 1 ) (0.044±0.08 L, p=0.014) and peak expiratory flow rate (PEFR) (0.47 ± 0.073 L/s, p=0.004). The filter did not affect other indices of lung function. Conclusion: The filter caused a statistically significant reduction in FEV 1 and PEFR; however, this difference was believed not to affect the clinical utility of routine lung function testing.

History

Publication title

Chest

Volume

107

Issue

4

Pagination

1045-1048

ISSN

0012-3692

Department/School

Tasmanian School of Medicine

Publisher

AMER COLL CHEST PHYSICIANS

Place of publication

USA

Repository Status

  • Restricted

Socio-economic Objectives

Clinical health not elsewhere classified

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