Validation of a novel automated system, Fluispotter®, for serial sampling of dried blood spots

Abstract

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 the 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 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, a reservoir for flushing solution, pumps and filterpaper, and a multi-lumen catheter placed in the brachial vein. We recruited healthy subjects for testing in an in-hospital setting. Fluispotter was attached by an anesthesiologist to 22 healthy subjects of which 9/22 (40.9%) participants had all 20 samples taken, which was lower than the goal of complete sampling in 80% of the subjects (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 the insertion and the removal of catheter as very low. A cortisol profile showed nadir values at midnight and highest values at 05:00 h. Although full sampling was not successful in all participants, the Fluispotter technology proved safe and highly acceptable to the participants producing the expected cortisol profile without the requirement of staff during sample collection.

Keywords: automated sampling; cortisol; diurnal; dried blood spots.

Figure 1

Cartoon of the Fluispotter principle. Left side: (A) Reservoir for sodium citrate flushing solution, (B) pump for flushing solution, (C) blood pump, (D) valve for uni-directional flow, and (E) PerkinElmer 226 paper strip. (A)–(E) are all enclosed in the sterile single-use Fluispotter Cartridge. (F) Multi-lumen catheter with (G) tip of catheter placed inside a peripheral vein. The catheter tip is designed to mix sodium citrate flushing solution to the blood flowing into the cartridge and to ensure that return blood is not mixed with the fresh blood sample. Right side: Sketch of Fluispotter placed on the left lower arm, with the sampling catheter placed in the brachial vein in the upper arm (unchanged, with permission: Adhikari K et al. Fluispotter, a novel automated and wearable device for accurate volume serial dried blood spot sampling, Bioanalysis 2020).

Figure 2

Number of successful venous blood samples obtained in the ITT population (n = 22) using Fluispotter, an automated device for serial blood sampling.

Figure 3

Cortisol profile based on samples in healthy subjects obtained using Fluispotter, an automated device for serial venous blood sampling.