1. Histamine challenge test assessed by the ratio of diaphragm EMG recorded from surface electrodes to tidal volume
- Author
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Ying-Mei Luo, Baiting He, Yingxin Wu, John Moxham, Joerg Steier, Caroline J. Jolley, Michael I. Polkey, and Yuanming Luo
- Subjects
medicine.medical_specialty ,Respiratory rate ,medicine.diagnostic_test ,business.industry ,Histamine Challenge Test ,respiratory tract diseases ,Diaphragm (structural system) ,chemistry.chemical_compound ,Airway resistance ,chemistry ,Internal medicine ,Cardiology ,medicine ,Bronchial challenge test ,Respiratory system ,business ,Tidal volume ,Histamine - Abstract
The magnitude of tidal volume (VT) depends on neural respiratory drive overcoming respiratory resistance. We hypothesized that the ratio of EMGdi, an index of neural drive, to VT could detect histamine induced changes in lower airway resistance given the assumption that respiratory resistance (except for the lower airway resistance) is unaffected by histamine. Conventional histamine challenge tests were undertaken in 44 asthma patients (age 47±14 years; FEV1% 76±14) diagnosed by a history of repeated attack of asthma and positive bronchial challenge test and 51 healthy subjects (age 36 ± 13 years; FEV1% 96 ± 11). Diaphragm EMG was recorded from chest wall surface electrodes (EMGdi) under the fixed breathing frequency (18 times/min.) and an additional inspiratory load to improve a signal–noise ratio. Airflow was recorded with a digital output flowmeter. ΔFEV1 correlated with ΔEMGdi /VT (r=0.63). Corresponding to ≥20% fall in FEV1 during histamine challenge test, change in EMGdi/VT in patients with asthma was significantly higher than that in healthy subjects who received maximal dose (7.8 µmol) of histamine (90.5% ± 75.5% vs 2.4% ± 21.7%, p
- Published
- 2018
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