Characteristics of Suction Effusion Fluid from Skin--A New Sample for Transcutaneous Measurement of Blood Biosubstances

Characteristics of a suction effusion fluid which was transcutaneously obtained from skin surface by suction was investigated as a new sample for transcutaneous measurement of blood biosubstances. The collection method of the suction effusion fluid from a rabbit skin without any damage on the skin has been developed by the authors. The steady effusion rate of 0.4μl/min/cm²(skin)was obtained from the rabbit skin eliminated its stratum corneum by the suction pressure of 400mmHg. Comparative biochemical analysis between the suction effusion fluid and blood indicated that glucose and non protein nitrogens(NPNs)were contained with approximately the same concentration. The concentration of proteins and fats were found to remarkably small in the suction effusion fluid. These constituents of the suction effusion fluid may leads a actual long lifetime of biosensors. The blood glucose change was detected in the suction effusion fluid with 15 min delay in response. It was possible to explain this delay by the buffer effect of interstitial volume in the epidermal tissue though there are many mechanisms for the delay. This response time was approximately same as that reported by biosensors inserted in subcutaneous tissue. These results encouraged in attainment of a transcutaneous continuous monitoring of blood glucose and/or NPNs by this method.