Importance

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Abstract

The arrangement comprises a passageway for receiving liquid for intravenous administration (IV) or the like. A hydrophilic microporous membrane having a first pore size is disposed in the passageway at a first point so that all liquid passes through the microporous membrane at said first point. A microporous filter is disposed below the membrane in the passageway to filter all liquid passing through the passageway at the second point. The membrane has a bubble point high enough to withstand the expected head of liquid below it (the gravity head of the IV set). Should liquid from the source as it proceeds through the passageway from the microporous membrane to the filter be exhausted, then when air or gas reaches the membrane the flow of liquid is stopped because the upper, microporous membrane acts as an automatic shut-off valve. Air does not pass through the wet hydrophilic microporous membrane as long as the pressure does not exceed its bubble point. Accordingly there is no danger of air arriving at or passing through the microporous membrane to air-lock the lower passageway. A bellows drip chamber may be arranged in the passageway immediately below the membrane and may act as a drip chamber. A further embodiment comprises such a bellows drip chamber arranged in the passageway below and immediately adjacent the microporous membrane, and a branch in the passageway in the section between the drip chamber and the hydrophilic filter which is used for the application of a secondary or auxiliary solution. In such a case, if the source of the secondary solution is higher than the source of the primary solution, the secondary solution will be preferentially administered. There will be no back-flow because air or gas in the bellows or drip chamber trapped immediately below the membrane will act as an air lock and prevent the backward flow of liquid in the first passageway because air or gas cannot pass through the hydrophilic upper microporous membrane which is wet by the liquid above it.

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First Claim