Blood microdialysis in humans: a new method for monitoring plasma compounds

A new venous microdialysis probe for humans was developed. The active area was made with cellulose membrane (220 mm outside diameter, length 20 mm, and 6000 molecular weight cut off). Glucose measurements were used to test it. The relative recovery was 50% in dialysates obtained in vitro, the step response was 91.8% in the first 2 min. The in vivo recovery was 65.8% obtained by the no net flux method, with the probe placed in the cubital vein of the subjects arms. Corrected glucose in dialysates was non significantly different from plasma glucose simultaneously collected. In healthy male volunteers from 18 to 37 years of age, mean 22.1 years, the glucose levels in the blood dialysates were measured every 30 min, 60 min before and 150 min after an oral load of 75 g of glucose or vehicle. Glucose increased significantly after the load. The differences with the control group were significant at 60 and 90 min after the treatment. The results showed the easy and safe application of this technique to monitor endogenous and exogenous compounds in the extracellular compartment of blood in out patients.