| 摘要 |
A blood filter such as may be used in a cordiopulmonary bypass system includes a housing having upper and lower chambers with a cylindrical filter element disposed in the lower chamber. The inlet to the housing is in the upper chamber, which is upstream of the lower chamber, and the outlet is through the lower chamber and communicates with the interior of the filter element. Thus, blood enters the upper chamber and flows to the lower chamber where it passes through the filter element from the outer side to the interior to remove microemboli such as gas bubbles, fat emboli and agglomerates, the filtered blood exiting through the outlet. In order to remove a substantial amount of the gas in the blood, and particularly gross bubbles, upstream of the filter element, the upper chamber is cylindrical and the inlet directs the blood tangentially to flow around the periphery of the chamber. An annular baffle extending around a major portion of the chamber maintains the peripheral flow which produces a centrifugal action causing the blood to flow at the wall of the chamber and the gas to separate and move to the central portion where it is vented through a hydrophobic membrane covering the central portion of the top wall of the chamber. Blood from the periphery of the upper chamber flows down to the lower chamber through a sponge ring which removes additional gas bubbles by causing the latter to coalesce into larger bubbles which move radially inwardly of the ring and rise to the upper chamber where they also are vented through the membrane. Any gas bubbles which remain in the blood and which are larger than the acceptable size are blocked by the filter element. The bubbles at the filter element eventually coalesce into larger bubbles which break away from the filter element and rise to the upper chamber where they are vented through the membrane.
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