Automatic Prothrombin Instrument

Various efforts to instrument coagulation determinations have proved either excessively costly or practically difficult. An instrument is described which is compact, reasonable in cost, and affords accurate, reproducible, nonsubjective determinations. Operation depends upon rotational sweep of precisely sized and located wires through the reaction mixture. Initial polymerization products are carried by one wire to a precision electrode arrangement which causes a sensitive electronic circuit to stop a timer. "Zero time" is automatically synchronized with the start of the reaction. A selector switch permits electrical adaptation of the electrode arrangement to determination of whole-blood clotting time. Extensive testing of a prototype instrument, confirmed by preliminary results obtained by various laboratories, indicates attainable accuracies of 0.3-second standard deviation.