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Electrical impedance tomography: New diagnostic possibilities using regional time constant maps

R. Pikkemaat1, K. Tenbrock2, S. Lehmann2, S. Leonhardt1
1Philips Chair for Medical Information Technology, RWTH Aachen University, Aachen, Germany; 2Department of Pediatrics, Dept. of Pediatrics, University Hospital, RWTH Aachen University, Aachen, Germany
[Applied Cardiopulmonary Pathophysiology 16: 212-225, 2012]


Pulmonary function tests are used to assess the severity of obstructive and restrictive lung diseases. These tests provide information on the whole lung considered as one compartment and can be used to globally describe the physical properties of flow resistance R and compliance C, but do not yield regional information. Electrical impedance tomography (EIT) is widely used in clinical research regarding ventilation monitoring. In this study, EIT recordings were performed simultaneously with spirometry during a forced expiration maneuver. We could show that EIT provides similar results to describe pulmonary mechanics. Therefore, seven patients (8-14 years) with asthma bronchiale were examined before and after therapy with Salbutamol to perform broncho spasmolysis. We found a relation between flow resistance R and global time constant tglobal with positive correlation r=0.88. Additionally, we propose the use of the regional time constant treg(x) (RTC-map) as a new imaging modality in a case study which demonstrates its performance considering broncho spasmolysis.

Key words: asthma bronchiale, diagnosis, electrical impedance tomography, pulmonary function test, time constant

Correspondence address
Dipl.-Ing. Robert Pikkemaat
Philips Chair for Medical Information Technology
RWTH Aachen
Pauwelsstr. 20
52074 Aachen
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