Importance

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Abstract

An aspiration syringe suitable for one-handed operation has a barrel defining a bore, a plunger consisting of a small cross-section plunger shaft extending into the bore and a first seal within the bore, carried by the distal end of the shaft for axial movement within the bore, and an end closure across the bore proximal of the first seal, the plunger shaft extending in sliding, sealed engagement therethrough. The first seal engages the wall defining the bore in vacuum-tight sealing engagement. The transverse cross-sectional area of the shaft is much less than the transverse cross-sectional area of the bore to provide a syringe-actuating vacuum chamber of substantial volume within the bore between the seal and the end closure. Movement of the plunger shaft to carry the first seal distally, from a first position, away from the end closure, creates a vacuum condition within the vacuum chamber sufficient that when the plunger shaft is released, the first seal is propelled by pressure differential acting across the first seal, while the distal end of the syringe is exposed to fluid, to automatically move the plunger proximally toward the end closure and cause entry of fluid into the distal portion of the bore distal of the first seal. A method of drawing fluid samples is also described.

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First Claim