TY - JOUR
T1 - Measurement of tidal volume by using transthoracic impedance variations in rats
AU - Davidson, K. G.
AU - Bersten, A. D.
AU - Nicholas, T. E.
AU - Ravenscroft, P. R.
AU - Doyle, I. R.
PY - 1999/2
Y1 - 1999/2
N2 - The application of impedance pneumography for monitoring respiration in small animals has been limited by problems with calibration. With improved instrumentation, we describe the calibration of tidal volume in anesthetized rats. The detection of changes in voltage, reflecting the electrical impedance variations associated with respiration, was optimized by using disposable adhesive silver-silver chloride electrodes, advanced circuitry, and analog-to-digital recording instrumentation. We found a linear relationship between change in impedance and tidal volume in individual rats (R2 ≥ 98%), which was strongly influenced by rat weight. Consequently, a calibration equation incorporating change in impedance and rat weight was derived to predict tidal volume. Comparison of the predicted and true tidal volumes revealed a mean R2 ≥ 98%, slopes of ~1, intercepts of ~0, and bias of ~0.07 ml. The predicted volumes were not significantly affected by either frequency of respiration or pulmonary edema. We conclude that impedance pneumography provides a valuable tool for the noninvasive measurement of tidal volume in anesthetized rats.
AB - The application of impedance pneumography for monitoring respiration in small animals has been limited by problems with calibration. With improved instrumentation, we describe the calibration of tidal volume in anesthetized rats. The detection of changes in voltage, reflecting the electrical impedance variations associated with respiration, was optimized by using disposable adhesive silver-silver chloride electrodes, advanced circuitry, and analog-to-digital recording instrumentation. We found a linear relationship between change in impedance and tidal volume in individual rats (R2 ≥ 98%), which was strongly influenced by rat weight. Consequently, a calibration equation incorporating change in impedance and rat weight was derived to predict tidal volume. Comparison of the predicted and true tidal volumes revealed a mean R2 ≥ 98%, slopes of ~1, intercepts of ~0, and bias of ~0.07 ml. The predicted volumes were not significantly affected by either frequency of respiration or pulmonary edema. We conclude that impedance pneumography provides a valuable tool for the noninvasive measurement of tidal volume in anesthetized rats.
KW - Edema
KW - Frequency
KW - Impedance pneumography
KW - Monitoring respiration
KW - Spontaneous breathing
UR - http://www.scopus.com/inward/record.url?scp=0033018958&partnerID=8YFLogxK
U2 - 10.1152/jappl.1999.86.2.759
DO - 10.1152/jappl.1999.86.2.759
M3 - Article
C2 - 9931218
AN - SCOPUS:0033018958
VL - 86
SP - 759
EP - 766
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 2
ER -