Acoustic analysis of respiratory sounds during methacholine challenge in preschool children
| Autor: | Sánchez D,Ignacio, Alvarez G,Cecilia, Clavería R,Cristián, Lisboa B,Carmen |
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| Jazyk: | Spanish; Castilian |
| Rok vydání: | 2001 |
| Předmět: | |
| Zdroj: | Revista médica de Chile, Volume: 129, Issue: 11, Pages: 1271-1278, Published: NOV 2001 Revista médica de Chile v.129 n.11 2001 SciELO Chile CONICYT Chile instacron:CONICYT |
| Popis: | Background: There are changes in inspiratory breath sound intensity in patients with airway obstruction. Airway narrowing may change sound spectral characteristics. Aim: To define the characteristics of lung sounds at standardized air flow during methacholine challenge and to compare acoustic changes with transcutaneous oxygen tension (PtcO2) during induced airway narrowing. Patients and methods: Forty asthmatic children (20 male) aged 5.2±1 years and 40 normal children (18 male), aged 5.6 ± 1 years were studied. All patients were free of respiratory tract infections one month before the study. A methacholine challenge from 0.06 to 8 mg/ml was performed; the test was ended when a fall in PtcO2 of >20% from baseline was observed or if the final concentration was reached. Subjects breathed through a pneumotachograph aiming at flows of 0.4 to 0.6 l/s. Respiratory sounds were recorded using contact sensors at the suprasternal notch and at the posterior right lower lobe. From average spectra, power at low (100-200 Hz=P1) and high frequencies (400-2000 =P2) was calculated. Frequencies below which 50% (F50) and 99% (SEF90) of the spectral power between 100 and 2000 Hz was contained, were also calculated. Results: In asthmatics, the metacholine concentration at which a 20% fall in PtcO2 was observed, was lower than in normal children (p< 0.05). There was an increase in P1 (p |
| Databáze: | OpenAIRE |
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