| 摘要 |
A blood sampling assembly is provided which has a cannula designed for intravenous penetration, a mechanism for applying negative pressure to the cannula, a chamber located between the cannula and the source of negative pressure, a one-way valve positioned within the chamber, and a venting member within the chamber which allows the venting of air as blood enters the chamber, but does not allow the passage of blood. A person drawing blood is enabled to visually determine when a needle is properly inside a vein through transparent walls of the chamber. Spillage of blood is avoided with the present assembly by the resistance of the one-way valve to flow distally from the intravenous cannula.
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