Interstitial fluid sampling using open flow microperfusion of subcutaneous adipose tissue

The objective of this study was to evaluate a novel method for interstitial fluid sampling. The method combines open flow microperfusion of subcutaneous adipose tissue and conductivity measurement of the sampled fluid for the estimation of the recovery. Interstitial fluid samples were obtained from 6 healthy volunteers in the fasting state and from 5 patients with diabetes mellitus during hypoglycaemic hyperinsulinemic clamp experiments. Glucose and free fatty acids (FFA) concentrations in the interstitial fluid samples were then measured. The recovery in the performed experiments varied between 5% and 40% at flow rate of 1÷2 μl·min^-1. The glucose concentration in the interstitial fluid was 95.0±5% (mean±SEM) of the plasma glucose. The FFA levels in the interstitial fluid samples ranged between 0.4 and 0.7 mmol·1^-1. In conclusion, by combining open flow microperfusion and conductivity measurement, sampling of the interstitial fluid from the subcutaneous adipose tissue and measurement of metabolites and substrates is feasible