Silver/silver chloride electrodes for measurement of potential difference in human bronchi
- aDepartment of Respiratory Physiology, bDepartment of Respiratory Medicine, cCochin Hospital, René Descartes University, Paris, France
- Dr I Fajac, Laboratoire de Physiologie Respiratoire, UFR Cochin Port-Royal, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France.
- Received 25 November 1997
- Revision requested 5 March 1998
- Revised 3 April 1998
- Accepted 19 May 1998
Abstract
BACKGROUND An easy and reliable method to measure potential difference (PD) in the lower airways would be of interest in the field of cystic fibrosis. We have developed silver/silver chloride (Ag/AgCl) electrodes to measure PD in the lower airways.
METHODS To validate this technique the nasal PD measured with Ag/AgCl electrodes and with conventional perfused electrodes was compared in 16 patients. The range of PD measured with Ag/AgCl electrodes in the lower airways during fibreoptic bronchoscopy was determined in 14 adult patients and in nine the reproducibility of this technique was examined.
RESULTS Nasal PD values measured with Ag/AgCl and perfused electrodes were highly correlated (r = 0.985, p<0.0001) and the limits of agreement (mean ±2SD of the difference) between the two methods were –1.91 mV and 1.53 mV. In the lower airways a progressive and slight decrease in PD values with decreasing airway diameter was observed in most patients. The mean (2SD) of the differences between the two tracheal measurements was 0.21 (1.73) mV.
CONCLUSIONS The use of Ag/AgCl electrodes gives a reliable and reproducible measurement of PD in the lower airways in humans.
