Patent GB-1490416-A (GB)
Title: Method and apparatus for determining coagulation times
IPC: G01N33/86
Filed: 1975-08-01
Abstract: 1490416 Method and apparatus for measuring coagulation: Blood coagulation test apparatus AMERICAN HOSPITAL SUPPLY CORP 1 Aug 1975 [27 Aug 1974 (2)] 32280/75 Headings G1B and G1S Apparatus 10, Fig. 3 for determining coagulation times of a test liquid such as blood to which a coagulating agent has been added manually, or automatically by swinging arms 95 holding pipettes 98, comprises a step by step turntable 18 supporting a number of segmental shaped trays 23, Fig. 10, each tray having a non-wettable floor of wax, silicone or silane treated fumed silica providing a pathway 29, 30 for guiding a pair of filaments 70 through a small quantity of test liquid 110, Fig. 4. The apparatus also comprises motor rotated take off reels 39, 40, co-operating with a roller 73 driven by a constant speed shaft 77 and motor 43 to move the filaments through the liquid at a predetermined rate from supply spools 78 over guide rollers 80 and pivoted guide arms 89, 51 and known means 120, Fig. 1 (not shown) are also provided for determining the time or filament distance interval between the addition of the coagulation agent and the commencement of movement of a'clot of the liquid along with the filaments. The two readily demountable and disposable reels 39, 40, Fig. 13, are driven by the constant speed motor 43 via a belt 44, pulleys 45-48 and a slip clutch 49, 50, but the testing rate of advancement of the filament 70 is reduced by a braking roller 73 when it is in the lowered position shown. The guide arms 89, 51 are controlled by a cam 24 which raises or lowers them either to hold the filaments 70 low in the tray 23, Fig. 4, where they may be either stopped or slow moving, or high and out of the pan 23 in a non-test position as in Figs. 8, 9 where they travel quicker and carry the clot 110 of liquid into a discharge trough 31 or quickly bring new sections of filaments into the region of the well part 28 of the tray. The cam 24 also indexes the turntable whilst the filaments are raised and presents another tray and sample for test. Each tray is bottom heated by means not shown and has a hole 33 in its bottom so that a light may be arranged to shine therethrough and co-operate with a photo-electric device actuated by a clot when entrained across the filaments and moving with them to obscure the light ray. The filaments which are of white horse hair, have radially extending fibres and are rotated in the same direction by the drive mechanism, Fig. 12 (not shown) to assist mixing. For clinical laboratory use, the apparatus may be programmed to conduct prothrombin time (PT) tests, activated partial thromboplastin time (APTT) tests, fibrinogen determinations, factor assays for blood coagulation factors II, V, VII, VIII, IX, X, XI, and XII, and identification and plasma assays. Initiation of the process leading to coagulation occurs upon the addition of a suitable coagulant. Where more than one agent is added, then the last one should be the coagulant. Thus in a partial thromboplastin time test first a cephaloplastin reagent and then a calcium chloride reagent are added, the latter being regarded as the coagulation initiator. The open topped cups 91, 92 containing the coagulant are oscillated gently by a mechanism such as that in Fig. 17 (not shown).