FDA-Clearance for HemoScreen Direct Capillary Sampling
24 Aug 2023
This recent FDA clearance has finally brought HemoScreen to its full potential as a true POC hematology analyzer with its proprietary single-use reagent cartridge, automatic sample preparation, and exceptionally simple blood collection procedure.
HemoScreen has been FDA-cleared since 2018 as a moderately complex point-of-care hematology system, and is to date, the only 5-part diff CBC analyzer FDA-cleared for point-of-care use.
The initial 510K clearance (K180020) included both venous and capillary (fingerstick) testing as comparable performance was demonstrated between the two whole blood matrices (venous and capillary). In that initial validation, the capillary samples were collected from a fingertip puncture using a standard lancet, and blood was delivered into a standard K2EDTA microtube. Samples were then drawn from the microtube into the cartridge sampler to be tested by both the HemoScreen and the predicate test system (Sysmex). The use of the microtubes was an artifact of the clinical study as it was necessary to obtain a sufficiently large sample volume to enable testing in duplicate by both instruments.
However, the HemoScreen Sampler was specifically designed to facilitate direct capillary blood collection, which makes the procedure significantly more straightforward and more practical as compared to the use of a microtube. This recent FDA clearance adds the option of collecting the blood sample directly from the finger into a disposable that is part of the cartridge.
This enables the collection of a sample directly from the finger without an intermediate tube which is normally very difficult to fill without getting sample clotting. Direct sampling is a significant advantage over other blood count devices, as it enables unparalleled ease of capillary blood collection that does not require a phlebotomist or physician, requires much less expertise, is quicker, painless, and is much less prone to pre-analytical errors.
Reduced blood clot formation, hemolysis, coagulation, and contamination.
No blood mixing and intermediate steps are required.
This sampling technique is particularly suited for use by trained medical staff, that are not necessarily lab technicians, phlebotomists, or even physicians. This significantly broadens access to conducting CBC testing across a number of clinical settings, such as ambulatory, emergency medicine, remote or understaffed clinics, research facilities, field or marine-based medical facilities, and on-site at hospital wards where nursing staff can easily access 5-part diff CBC results without waiting for the lab.
How Does HemoScreen’s Direct Sampling Work?
Direct capillary sampling is at the heart of HemoScreen’s unique design philosophy of operational simplicity and ease of use – especially for the near-patient environment. The sample kit includes a disposable cartridge and a disposable blood collection and dispensing component called a “Sampler”. The Sampler mates with the cartridge and transfers the blood sample into it once the cartridge is inserted into HemoScreen to begin the testing procedure.
The sampling process is straightforward: the finger is pricked with a standard lancet, the first drop of blood is wiped, and the next drop that forms is collected into the capillaries that comprise the Sampler.
The two capillary tubes are coated with K2EDTA and due to the large area-to-volume ratio mixing is not required. The capillaries include a plug that allows air to escape from the back but blocks the blood from further moving. These plugs make it easy for the user to determine that the capillaries are full and prevent overfilling.
Once the capillaries are filled, the Sampler is inserted into the cartridge and locks in, then the cartridge is inserted into the reader and the test begins.