[The suction effusion fluid is useful as a sample for blood biochemistry]

We examined whether the suction effusion fluid could be used as a new sample for blood biochemistry. The fluid was obtained from the skin surface of female mongrel dogs by transcutaneous suction after removal of the horny substance. The appropriate intraluminal pressure for suction was 300 mmHg at which the effusion fluid flow rate was 0.6 microliter/min/cm2. The blood biochemistry examination revealed that the creatinine (Cr) and urea (BUN) concentrations in the suction effusion fluid were similar to those in plasma and that the protein and lipid concentrations were much smaller than those in plasma. The six-hour study showed that the effusion fluid could be obtained for hours at the same skin area and that the Cr and BUN concentrations were consistently close to those in plasma. In uremia models, the Cr and BUN concentration in the suction effusion fluid was similar to and had an extremely high correlation (r = 0.985 and 0.982 respectively) to that in plasma through out the range for clinical practice. The skin biopsy revealed that the regeneration of the horny substance had started at one week after the suction and complete recovery was seen at four weeks. The invasiveness of the suction seemed to be small. The suction effusion fluid is a reliable material for measurement of Cr and BUN in plasma and, as it contains much less proteins and lipids, will be a good sample for biosensors.