[en] BACKGROUND AND OBJECTIVE: Lung mechanics measurements provide clinically useful information about disease progression and lung health. Currently, there are no commonly practiced methods to non-invasively measure both resistive and elastic lung mechanics during tidal breathing, preventing the important information provided by lung mechanics from being utilised. This study presents a novel method to easily assess lung mechanics of spontaneously breathing subjects using a dynamic elastance, single-compartment lung model. METHODS: A spirometer with a built-in shutter was used to occlude expiration during tidal breathing, creating exponentially decaying flow when the shutter re-opened. The lung mechanics measured were respiratory system elastance and resistance, separated from the exponentially decaying flow, and interrupter resistance calculated at shutter closure. Progressively increasing resistance was added to the spirometer mouthpiece to simulate upper airway obstruction. The lung mechanics of 17 healthy subjects were successfully measured through spirometry. RESULTS: N = 17 (8 female, 9 male) healthy subjects were recruited. Measured decay rates ranged from 5 to 42/s, subjects with large variation of decay rates showed higher muscular breathing effort. Lung elastance measurements ranged from 3.9 to 21.2 cmH[Formula: see text]O/L, with no clear trend between change in elastance and added resistance. Resistance calculated from decay rate and elastance ranged from 0.15 to 1.95 cmH[Formula: see text]Os/L. These very small resistance values are due to the airflow measured originating from low-resistance areas in the centre of airways. Occlusion resistance measurements were as expected for healthy subjects, and increased as expected as resistance was added. CONCLUSIONS: This test was able to identify reasonable dynamic lung elastance and occlusion resistance values, providing new insight into expiratory breathing effort. Clinically, this lung function test could impact current practice. It does not require high levels of cooperation from the subject, allowing a wider cohort of patients to be assessed more easily. Additionally, this test can be simply implemented in a small standalone device, or with standard lung function testing equipment.
Disciplines :
Anesthesia & intensive care
Author, co-author :
Howe, S. L.; Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
März, M.; Institute of Technical Medicine (ITeM), Furtwangen University, Villingen-Schwenningen, Germany
Krüger-Ziolek, S.; Institute of Technical Medicine (ITeM), Furtwangen University, Villingen-Schwenningen, Germany
Laufer, B.; Institute of Technical Medicine (ITeM), Furtwangen University, Villingen-Schwenningen, Germany
Pretty, C.; Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
Shaw, G. M.; Department of Intensive Care, Christchurch Hospital, Christchurch, New Zealand
Desaive, Thomas ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Thermodynamique des phénomènes irréversibles
Möller, K.; Institute of Technical Medicine (ITeM), Furtwangen University, Villingen-Schwenningen, Germany
Chase, J. G.; Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
Language :
English
Title :
Measuring lung mechanics of expiratory tidal breathing with non-invasive breath occlusion
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