Title of Invention

AN ARTERIAL BLOOD FILTER

Abstract

The invention provides an arterial blood filter comprising a shell having a top cover and a bottom plate with an outlet, said shell being provided with an angled inlet through which the blood enters into the shell, a depth filter inside the shell attached to said bottom plate and a vent cap being provided on the top cover. Preferably a volume displacer is provided at the center portion of the shell, to reduce the held-up volume occupied by the filtered blood inside the filter. A screen filter with a cut-off of 40 to 200 microns may be provided at the outlet. The depth filter may have a cut- off of 20 to 40 microns. For creating multiple circular '0' elliptical flow of blood paths through the filter, the length of the shell should be more than the diameter of the shell.

Full Text

The invention relates to an arterial blood filter, which is used to filter blood particularly during operation. During bypass surgery, blood comes in contact with non-physiological components forming micro-aggregates. When the blood passes through the tubes connecting heart-lung machine, cardiotomy reservoir and oxygenerator, it will acquire micro air emboli. Apart from this, cut bone debris, fat and surgical debris gets added to the blood. These foreign particles will have an average size of 30 to 180 microns and a 40 microns arterial filter is recommended and used internationally. If micro-aggregate and particles are not effectively removed from the blood during a bypass surgery, it can be fatal due to febrile reaction, respiratory distress and nonfunctioning of heart, lung and kidney after operation. If micro air embolism enters systemic circulation, it can result in brain disorder, coma and even death. In order to effectively remove micro-aggregates and particles from blood, the arterial blood filter according to the invention uses a depth filter which provides maximum retention capability, minimum flow resistance throughout the period of blood passage and maximum through put while reducing the turbulence, hold up volume and blood contact surface area. Another feature of the arterial blood filter according to the invention is its internally guided flow engineering. The blood enters the filter through an angled inlet located near the top. This angled inlet enable the micro air emboli in the blood to reach the top portion of the filter and get vented through a vent port provided in top cover. Remaining micro air emboli in the blood will also come to the top vent due to the circumfrencial and top down circular or elliptical flow dynamics induced by the angled inlet and shell design. Yet another feature of the arterial blood filter is assured double safety with an additional screen filter strategically positioned before the outlet to filter particles of higher sizes. Thus the invention provides an arterial blood filter comprising a shell having a top cover and a bottom plate with an outlet, said shell being provided with an angled inlet through which the blood enters into the shell, a depth filter inside the shell attached to said bottom plate and a vent cap being provided on the top cover. Preferably a volume displacer is provided at the center portion of the shell, to reduce the held-up volume occupied by the filtered blood inside the filter. A screen filter with a cut-off of 40 to 200 microns may be provided at the outlet. The depth filter may have a cut-off of 20 to 40 microns. For creating multiple circular 'O' elliptical flow of blood paths through the filter, the length of the shell should be more than the diameter of the shell. The constructional features of the arterial filter according to the invention is shown in the figure in the accompanying drawing. A shell (1) preferably made of bio-compatable polycarbonate comprises a top cover (2) and a bottom plate (3) with an outlet (4). An angled inlet (5) is provided on the shell for introducing blood into the shell at an angle to the vertical axis of the shell. The blood is fed to the inlet (5) with pressure so that the blood stream jets upward with a centrifugal force and fall on a depth filter (6) attached to the bottom plate (3). The depth filter is preferably provided with a support (10). The top cover (2) is provided with an air vent (7) to allow air trapped in the blood stream to escape and make it free of micro air emboli. The depth filter (6) located in the shell (1) is preferably made bio-compatable polyester fibre material. A volume displacer (8) is preferably provided inside the depth filter (6) in order to reduce the dead volume of the filter (6). It is desirable to provide a screen filter (9) having a mesh size of 40 to 200 microns before the outlet (4). The depth filter (6) filters effectively particles with size greater than 20 microns. The arterial filter according to the invention may be used effectively for an open heart surgery by connecting the arterial filter at the outlet of an oxygenerator through a fluid pump. WE CLAIM: 1. An arterial blood filter comprising a shell (1) having a top cover (2) and a bottom plate (3) with an outlet (4), an air vent (7) being provided on said top cover (2) characterized in that said shell is provided with an angled inlet (5) for introducing blood into the shell at an angle to the vertical axis of the shell; a depth filter is located inside the said shell attached to said bottom plate (3); and a screen filter (9) is provided before the outlet to filter particles of higher sizes. 2. The arterial blood filter as claimed in claim 1, wherein the angled inlet (5) and depth filter (6) are positioned for guiding the incoming blood into a circular 'O' elliptical flow for efficient air removal. 3. The arterial blood filter as claimed in any one of the preceding claims, wherein the length of the said shell is greater than the diameter for a given volume of the shell to ensure multiple circular '0' elliptical blood paths which improve air removal capacity fight at entry stage. The arterial blood filter as claimed in claim 1, wherein said depth filter (6) is provided with a support (10). The arterial blood filter as claimed in claims 1 or 2, wherein the said depth filter (6) is made of a biocompatable polyester fibre material. 6. The arterial blood filter as claimed in any one of the preceding claims, wherein inside the said depth filter (6) a volume displacer (8) is provided to reduce the dead volume of the said depth filter (6). 7. The arterial blood filter as claimed in any one of the preceding claims wherein, mesh size of the screen filter (9) is 40 to 200 microns. DATED THIS 28 DAY OF MARCH 2002

Documents:

225-mas-2002 claims duplicate.pdf

225-mas-2002 description (complete) duplicate.pdf

225-mas-2002 drawing duplicate.pdf

225-mas-2002-abstract.pdf

225-mas-2002-claims.pdf

225-mas-2002-correspondnece-others.pdf

225-mas-2002-correspondnece-po.pdf

225-mas-2002-description(complete).pdf

225-mas-2002-drawings.pdf

225-mas-2002-form 1.pdf

225-mas-2002-form 18.pdf

225-mas-2002-form 26.pdf

225-mas-2002-form 3.pdf

225-mas-2002-form 5.pdf

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