Retractable-needle cannula insertion set with refinements to better control leakage, retraction speed, and reuse

Abstract From the Canadian patent

Leakage of blood from the insertion set during and after, safety-needle retraction is suppressed by components that, receive and retain flash blood for viewing -- notwithstanding forces developed within the device in retraction. One preferred such system includes a flash chamber that moves with the retracting needle, within a hollow handle carrying a relatively, high flow-impedance element which allows air exhaust from the chamber into the handle to admit flash blood -- but isolates blood in the chamber from retraction-generated increase in air pressure in the handle. Energy-absorbing components control or compensate for retraction speed to provide quiet, smooth retraction -- while yet …