FIELD: medicine.
SUBSTANCE: invention relates to medicine. A needle unit contains a transparent or semitransparent casing, which has an input end and an output end for a flowing medium, a chamber of blood ejection and means for passing the flowing medium between them. The means for passing the flowing medium contains a blocking element for directing the flowing medium in the means for passing the flowing medium in such a way that it moves along the longest way. Input and output cannulas deviate from the casing. The cannulas are, in fact, aligned with each other on the longitudinal axis and are connected to the chamber. The external end of the output cannula is closed with a sealing cuff. Relative volumes of the cannulas, the chamber and the cuff are selected in such a way as to provide the fast and reliable ejection of blood, which is an index of introduction of the needle into the vein. A ermeable element, dividing the internal space of the casing into the first and second chambers, is located inside the casing. The second chamber is adapted for supporting inside it negative pressure relative to the outer environment.
EFFECT: prevention of blood leaking from the needle tip after its removal from the patient's vein.
37 cl, 25 dwg
