Endocrine Abstracts

Repeated blood sampling is required in certain clinical and research settings, which is currently performed by drawing blood from venous catheters requiring manual handling of each sample at time of collection. A novel body-worn device for repeated serial samples, Fluispotter®, with automated extraction, collection and storage of up to 20 venous dried blood spot samples (DBS) over the course of 20 h may overcome problems with current methods for serial sampling. The purpose of this study was to assess the performance and safety of Fluispotter for the first time in healthy subjects. Fluispotter consists of a cartridge with tubing, reservoir for flushing solution, pumps and filter-paper and a multi-lumen catheter placed in the brachial vein. The volumetric DBS technology used in the Fluispotter has previously been tested ex vivo for cortisol assessment by comparing cortisol concentrations from dried blood spots with cortisol plasma samples¹. The interassay accuracy and precision were less than 10% across a range of different haematocrit values. The plasma cortisol concentration was predicted from cortisol concentration measurements extracted from the DBS using the following formula:

PC_plasma=C_(DBS)/((0.92+(-0.876 x HCT))).

We recruited healthy subjects for testing in an in-hospital setting. Fluispotter was attached to 22 healthy subjects of which 9/22 (40.9 %) participants had all 20 samples taken successfully, which was lower than the expected 80% (P=0.02). The main reason for sample failure was clogging of blood flow which was observed in 11/22 (50 %) of the participants. No serious adverse events occurred, and the participants rated the pain from insertion and removal of catheter as very low. A cortisol profile showed nadir values at midnight and highest values at 5 a.m. In conclusion, although full sampling was not successful in all participants, the Fluispotter technology proved safe and highly acceptable to the participants. The blood clogging was expected to be solvable by simple technical amendments. Producing the expected cortisol profile without the requirement of staff during sample collection provides promising future applications for studying circadian variations of different compounds in the circulation.

This work was funded by Innovation Fund Denmark (#5164-00008B): 1. Adhikari et al. Fluispotter, a novel automated and wearable device for accurate volume serial dried blood spot sampling. Bioanalysis. Methodology. Vol. 12:10; p.665-681