# US 2016/0354530 A1 · Filters with gradient porosities > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0354530 A1 - Document ID: US20160354530A1 - Status: Published application - Kind: A1 - Application number: 14/728,241 - Filed: 2015-06-02 - Published: 2016-12-08 - Earliest claimed: 2015-06-02 - Assignees: Terumo Cardiovascular Systems Corporation - Applicants: Terumo Cardiovascular Systems, Inc. - Inventors: Louis F. Peticca; Jeffrey E. Troyan; Eric E. Brooking - Web page: https://patentgrep.com/patent/US20160354530A1 ## CPC - A61M 1/3627: {Degassing devices; Buffer reservoirs; Drip chambers; Blood filters} - A61M 1/3623: {Means for actively controlling temperature of blood} - A61M 1/3632: {Combined venous-cardiotomy reservoirs} - B01D 19/0031: {by filtration} - B01D 35/30: Filter housing constructions - A61M 1/3633: {Blood component filters, e.g. leukocyte filters} - A61M 2205/75: with filters - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) ## Abstract Multiple embodiments of medical filters are described. For example, this document describes extracorporeal blood filters that have a gradient of filter pore sizes at different portions of the filter element. The gradient of filter pore sizes may enhance the filter's potential for capturing and removing gaseous bubbles that may be present in the blood or other fluid that is flowing through the filter. ## Claims ### Claim 1 A venous blood reservoir for use in an extracorporeal circuit, the reservoir comprising: an outer housing defining an internal space, the outer housing having an upper housing portion and a lower housing portion; and a venous filter comprising a porous filter material disposed within the internal space, the filter having an upper filter end portion and a lower filter end portion, the upper filter end portion disposed adjacent the upper housing portion and the lower filter end portion disposed adjacent the lower housing portion, wherein an average pore size of the porous filter material disposed at the lower filter end portion is less than an average pore size of the porous filter material disposed at the upper filter end portion. ### Claim 2 (depends on 1) The reservoir of claim 1, wherein the venous filter comprises three or more distinct portions of the porous filter material. ### Claim 3 (depends on 1) The reservoir of claim 1, the venous filter also having a middle filter portion disposed between the upper filter end portion and the lower filter end portion, wherein an average pore size of the porous filter material disposed at the middle filter portion is larger than the average pore size of the porous filter material disposed at the lower filter end portion, and wherein the average pore size of the porous filter material disposed at the middle filter portion is less than the average pore size of the porous filter material disposed at the upper filter end portion. ### Claim 4 (depends on 1) The reservoir of claim 1, further comprising a cardiotomy filter. ### Claim 5 (depends on 1) The reservoir of claim 1, wherein the venous filter comprises a continuous piece of the porous filter material that has a gradually changing pore size along a length of the filter. ### Claim 6 (depends on 1) The reservoir of claim 1, wherein the venous filter comprises four or more distinct portions of the porous filter material. ### Claim 7 (depends on 1) The reservoir of claim 1, wherein the average pore size of the porous filter material disposed at the lower filter end portion is less than 40 microns, and wherein the average pore size of the porous filter material disposed at the upper filter end portion is greater than 40 microns. ### Claim 8 A method of using an extracorporeal circuit during a surgery on a patient, the method comprising: transferring blood from the patient into a venous blood reservoir, the venous blood reservoir comprising: an outer housing defining an internal space, the outer housing having an upper housing portion and a lower housing portion; and a venous filter comprising a porous filter material disposed within the internal space, the filter having an upper filter end portion and a lower filter end portion, the upper filter end portion disposed adjacent the upper housing portion and the lower filter end portion disposed adjacent the lower housing portion, wherein an average pore size of the porous filter material disposed at the lower filter end portion is less than an average pore size of the porous filter material disposed at the upper filter end portion; passing the blood through the venous filter, wherein the average pore size of the porous filter material disposed at the lower filter end portion adapts the venous filter to cause the blood to dwell within the venous filter for a longer period of time than the blood would dwell if the pore size of the lower filter end portion was the same as the pore size of the upper filter end portion, thereby allowing for improved removal of gaseous emboli from the blood; and draining the blood out of the venous blood reservoir. ### Claim 9 (depends on 8) The method of claim 8, wherein the average pore size of the porous filter material disposed at the lower filter end portion is less than 40 microns, and wherein the average pore size of the porous filter material disposed at the upper filter end portion is greater than 40 microns. ### Claim 10 (depends on 8) The method of claim 8, wherein at least some gaseous bubbles are removed from the blood by the venous filter as the blood passes through the filter. ### Claim 11 (depends on 8) The method of claim 8, wherein at least some gaseous bubbles are broken into smaller gaseous bubbles by the venous filter as the blood passes through the filter. ### Claim 12 A medical filter comprising: a housing defining an internal space and a longitudinal axis, the housing having an upper housing portion and a lower housing portion; and a filter element comprising a porous filter material disposed in general longitudinal alignment within the internal space, the filter element having an upper portion and a lower portion, wherein the porous filter material disposed at the lower portion is finer than the porous filter material disposed at the upper portion. ### Claim 13 (depends on 12) The medical filter of claim 12, wherein the filter element comprises three or more distinct portions of the porous filter material. ### Claim 14 (depends on 12) The medical filter of claim 12, the filter element also having a middle portion disposed between the upper portion and the lower portion, wherein the porous filter material disposed at the middle portion is coarser than the porous filter material disposed at the lower portion, and wherein the porous filter material disposed at the middle portion is finer than the porous filter material disposed at the upper portion. ### Claim 15 (depends on 12) The medical filter of claim 12, wherein the filter element comprises two or more distinct portions of the porous filter material. ### Claim 16 (depends on 12) The medical filter of claim 12, wherein the filter element comprises a continuous piece of the porous filter material that has a gradually changing pore size along a length of the filter element. ### Claim 17 (depends on 12) The medical filter of claim 12, wherein the filter element comprises four or more distinct portions of the porous filter material. ### Claim 18 A method of filtering blood through a filtering system, the method comprising: inputting the blood to the filtering system at a bottom region of a chamber defined by a filter and an upper air space, the filter comprising a porous filter material, the filter having an upper end portion and a lower end portion, wherein an average pore size of the porous filter material disposed at the lower end portion is less than an average pore size of the porous filter material disposed at the upper end portion; and filtering the blood such that the blood flows outwardly through pores in the filter while gaseous bubbles prevented from flowing through the pores in the filter rise in the chamber toward the upper air space. ### Claim 19 (depends on 18) The method of claim 18, wherein the average pore size of the porous filter material disposed at the lower end portion is less than 40 microns, and wherein the average pore size of the porous filter material disposed at the upper end portion is greater than 40 microns.