Abstract
Objective
To measure temperature and impedance changes at various depths in human tissue in vivo, after the application of transdermal direct current (TDC).
Design
Prospective experimental single cohort study.
Setting
Genesis Surgery Center.
Participants
Eight patients who underwent a lumbar rhizotomy for chronic low back pain consented to an additional procedure involving TDC with saline solution. Two TDC electrodes (active, 55mm; dispersive, 62mm) were placed 51–56cm apart, and a current amplitude of 4.0mA was delivered for an average of 18.4minutes.
Main outcome measures
Temperature and impedance readings recorded by the RFG-3CF Lesion Generator probe, from depths of 5cm to the skin surface were obtained before TDC, and just before TDC was terminated. Data were analyzed using non-parametric statistics.
Results
A statistically significant decrease in impedance (mean 48Ω, 95% confidence interval: 26–70) was detected, but there was no interaction of impedance change with tissue depth. Overall, tissue temperature decreased by 2°C (95% confidence interval: 1.9–2.8) from baseline to the second measurement and the change was greatest within 1cm of the surface.
Conclusion
The data suggest that transdermal delivery of medications to deep tissues of the lumbar region may not be enhanced by use of direct current as applied clinically.
Citation
Measurement of soft tissue temperature and impedance following the application of transdermal direct current
Scott J. Benjamin, John N. Flood, Roy Bechtel, Gad Alon
Physiotherapy - June 2007 (Vol. 93, Issue 2, Pages 114-120, DOI: 10.1016/j.physio.2006.11.008)