MICRODIALYSIS PROBE FOR TRANSCUTANEOUS MONITORING OF ETHANOL AND GLUCOSE IN HUMANS

A heated (42 degrees C) microdialysis probe and its application for co ntinuous transcutaneous sampling of ethanol and glucose through cellop hane-stripped forearm skin are described. Ethanol and glucose concentr ations in the dialysate were measured on-line with continuous-flow ana lysis and compared with blood values in human volunteers after ethanol consumption (n = 4) and oral glucose testing (n = 5), respectively. F or ethanol and glucose, the dialysate and blood concentrations were li nearly related in each subject (r greater than or equal to 0.91, P< (0 .005), although the dialysate-to-blood ratio varied among subjects. Th e recovery in vivo was 22.4 +/- 22.7 and 4.7 +/- 2.3% (SD) of the reco very in vitro for ethanol and glucose, respectively. The dialysate glu cose concentration was independent of blood flow. When the probe tempe rature was increased from 32 to 42 degrees C, the dialysate-to-blood g lucose ratio increased, with 2.4 +/- 1.4%/degrees C (SD) in fasting su bjects (n = 4), which was similar to an increase of 2.1 +/- 0.045%/ de grees C in dialysate-to-medium ratio in vitro. The present approach fo r transcutaneous sampling may possibly be used for other substances of low molecular weight as well.