# US 4,994,047 A · Multi-layer cannula structure > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,994,047 A - Document ID: US4994047A - Status: Granted - Kind: A - Application number: 07/191,007 - Filed: 1988-05-06 - Granted: 1991-02-19 - Earliest claimed: 1988-05-06 - Assignees: Menlo Care, Inc. - Inventors: Jack M. Walker; Joseph R. Thomas - Web page: https://patentgrep.com/patent/US4994047A ## CPC - A61M 25/0045: {multi-layered, e.g. coated (coating materials A61L29/08)} - A61L 29/06: obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds - A61M 25/0054: {with regions for increasing flexibility} - A61M 2025/0057: {Catheters delivering medicament other than through a conventional lumen, e.g. porous walls or hydrogel coatings} - A61M 2025/0064: {which become stiffer or softer when heated} - 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)} - A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K) ## Abstract A swellable cannula is formed of concentric inner and outer hydrophilic and substantially non-hydrophilic layer structures. The hydrophilic layer structure comprises at least 2/3rds of the cross-sectional area of the wall of the cannula. The substantially non-hydrophilic layer structure is either substantially water impermeable or allows water to pass through at a controlled rate. The substantially non-hydrophilic layer structure may also control the diffusion of medicaments. The cannula has controlled softenability and swellability characteristics. ## Claims ### Claim 1 A swelling multilayer cannula having proximal and distal end portions and a wall defining an inner lumen, comprising: (a) a hydrophilic layer structure having one or more hydrophilic layers having respective outer and inner surfaces and being formulated of a hydrophilic material characterized in that it increases in volume more than 1.3:1 upon contact with an aqueous medium at 37.degree. C., said hydrophilic layer structure comprising at least 2/3rds of the cross-sectional area of said wall, said inner lumen swelling such that its cross-sectional area increases more than 20% upon contact of said hydrophilic layer structure with said aqueous medium at 37.degree. C.; and (b) a substantially non-hydrophilic layer structure having one or more substantially non-hydrophilic layers having respective outer and inner surfaces and being formulated of a substantially non-hydrophilic material, an outer or inner surface of each of said hydrophilic layers being bonded to a corresponding inner or outer surface of at least one of said substantially non-hydrophilic layers, said bonded hydrophilic and substantially non-hydrophilic layers being of a construction such that they remain bonded to one another following swelling of said lumen such that its cross-sectional area increases more than 20% upon contact of said hydrophilic layer structure with said aqueous medium at 37.degree. C. ### Claim 2 (depends on 1) A cannula as set forth in claim 1, wherein an innermost of said hydrophilic and substantially non-hydrophilic layers is a first of said substantially non-hydrophilic layers and defines said lumen and wherein a first of said hydrophilic layers has its inner surface bonded to the outer surface of said first substantially non-hydrophilic layer. ### Claim 3 (depends on 2) A cannula as set forth in claim 2, further including, in said lumen: at least one partition separating said lumen into at least two generally coextensive channels. ### Claim 4 (depends on 1) A cannula as set forth in claim 1, wherein said first substantially non-hydrophilic layer extends from a proximal end portion of said cannula but stops short of said distal end portion of said cannula. ### Claim 5 (depends on 1) A cannula as set forth in claim 1, wherein an innermost of said hydrophilic and substantially non-hydrophilic layer is a first of said hydrophilic layers and defines said lumen and wherein a first of said non-hydrophilic layers has its inner surface bonded to the outer surface of said first hydrophilic layer. ### Claim 6 (depends on 5) A cannula as set forth in claim 5, wherein said first substantially non-hydrophilic layer controls the diffusion rate of water or medicaments from said first hydrophilic layer to said outer surface of said first substantially non-hydrophilic layer. ### Claim 7 (depends on 1) A cannula as set forth in claim 1, wherein at least a first substantially non-hydrophilic layer of said substantially non-hydrophilic layer structure includes controlling means for controlling the lengthwise expansion of said cannula as it swells. ### Claim 8 (depends on 7) A cannula as set forth in claim 7, wherein said controlling means comprises a plurality of fibers oriented lengthwise and located in said first substantially non-hydrophilic layer. ### Claim 9 (depends on 7) A cannula as set forth in claim 7, wherein said controlling means comprises residual axial stress in said first substantially non-hydrophilic layer. ### Claim 10 (depends on 7) A cannula as set forth in claim 7, wherein said controlling means controls said lengthwise expansion to be no more than 5% when an outer diameter of said wall increases 15%. ### Claim 11 (depends on 1) A cannula as set forth in claim 1, wherein said one substantially non-hydrophilic layer is formulated of a thermoplastic material. ### Claim 12 (depends on 1) A cannula as set forth in claim 1, wherein said one substantially non-hydrophilic layer is formulated of a polyurethane material. ### Claim 13 (depends on 1) A cannula as set forth in claim 1, wherein said one substantially non-hydrophilic layer is formulated of an elastomeric material. ### Claim 14 (depends on 1) A cannula as set forth in claim 1, wherein said one substantially non-hydrophilic layer has a softening ratio of more than 5:1 on being raised from about 20.degree. C. to 37.degree. C. ### Claim 15 (depends on 1) A cannula as set forth in claim 1, wherein said one hydrophilic layer is formulated of a material having a 2.5% Secant modulus of less than 20,000 psi when hydrated at 37.degree. C. ### Claim 16 (depends on 1) A cannula as set forth in claim 1, wherein said cannula decreases in 2.5% Secant modulus more than 10:1 upon exposure to an aqueous medium at 37.degree. C. ### Claim 17 (depends on 1) A cannula as set forth in claim 1, wherein said hydrophilic layer material of said cannula comprises: (a) a first phase which comprises a substantially non-hydrophilic polymeric component; and (b) a second phase which comprises a hydrophilic polymeric component; said material (i) being capable of absorbing water to an extent that it softens with a softening ration of at least about 2:1 and/or swells with a swelling ratio of at least about 1.3:1; and (ii) when substantially completely hydrated at 37.degree. C., having an energy to break of at least about 700 N-cm/cm.sup.3 and a 2.5% Secant modulus of less than about 7,000 N/cm.sup.2. ### Claim 18 (depends on 1) A cannula as set forth in claim 1, wherein said material, when at 37.degree. C., has an energy to break of at least about 700 N-cm/cm.sup.3 and a 2.5% Secant modulus of less than about 7,000 N/cm.sup.2. ### Claim 19 A swelling multilayer cannula having proximal and distal end portions and a wall defining an inner lumen, comprising: (a) a hydrophilic layer structure having one or more hydrophilic layers having respective outer and inner surfaces and being formulated of a hydrophilic material characterized in that it increases in volume more than 1.3:1 upon contact with an aqueous medium at 37.degree. C., said hydrophilic layer structure comprising at least 1/2rds of the cross-sectional area of said wall, said inner lumen swelling such that its cross-sectional area increases more than 20% upon contact of said hydrophilic layer structure with said aqueous medium at 37.degree. C.; (b) a substantially non-hydrophilic layer structure having one or more substantially non-hydrophilic layers having respective outer and inner surfaces and being formulated of a substantially non-hydrophilic material, an outer or inner surface of each of said hydrophilic layers being bonded to a corresponding inner or outer surface of at least one of said substantially non-hydrophilic layers, said bonded hydrophilic and substantially non-hydrophilic layers being of a construction such that they remain bonded to one another following swelling of said lumen such that its cross-sectional area increases more than 20% upon contact of said hydrophilic layer structure with said aqueous medium at 37.degree. C.; and wherein an innermost of said hydrophilic and substantially non-hydrophilic layers is a first of said substantially hydrophilic layers and defines said lumen, wherein a first of said substantially non-hydrophilic layers has its inner surface bonded to the outer surface of said first substantially hydrophilic layer and wherein a second of said hydrophilic layers has its inner surface bonded to the outer surface of said first substantially non-hydrophilic layer. ### Claim 20 A swelling multilayer cannula having proximal and distal end portions and a wall defining an inner lumen, comprising: (a) a hydrophilic layer structure having one or more hydrophilic layers having respective outer and inner surfaces and being formulated of a hydrophilic material characterized in that it increases in volume more than 1.3:1 upon contact with an aqueous medium at 37.degree. C., said hydrophilic layer structure comprising at least 2/3rds of the crosssectional area of said wall, said inner lumen swelling such that its cross-sectional area increases more than 20% upon contact of said hydrophilic layer structure with said aqueous medium at 37.degree. C.; (b) a substantially non-hydrophilic layer structure having one or more substantially non-hydrophilic layers having respective outer and inner surfaces and being formulated of a substantially non-hydrophilic material, an outer or inner surface of each of said hydrophilic layers being bonded to a corresponding inner or outer surface of at least one of said substantially non-hydrophilic layers, said bonded hydrophilic and substantially non-hydrophilic layers being of a construction such that they remain bonded to one another following swelling of said lumen such that its crosssectional area increases more than 20% upon contact of said hydrophilic layer structure with said aqueous medium at 37.degree. C.; an innermost of said hydrophilic and substantially non-hydrophilic layers being a first of said substantially non-hydrophilic layers and defining said lumen; a first of said hydrophilic layers having its inner surface bonded to the outer surface of said first substantially non-hydrophilic layer; and wherein said substantially non-hydrophilic layer structure includes a second substantially non-hydrophilic layer having its inner surface bonded to the outer surface of said first hydrophilic layer. ### Claim 21 (depends on 20) A cannula as set forth in claim 20, wherein a second of said hydrophilic layers has its inner surface bonded to the outer surface of said second substantially non-hydrophilic layer and wherein said substantially non-hydrophilic layer structure includes a third substantially non-hydrophilic layer having its inner surface bonded to the outer surface of said second hydrophilic layer. ### Claim 22 (depends on 21) A cannula as set forth in claim 21, wherein said first substantially non-hydrophilic layer controls the diffusion rate of water or medicaments between said first hydrophilic layer and said lumen, said third substantially non-hydrophilic layer controls the diffusion rate of water or medicaments between said second hydrophilic layer and the outer surface of said third substantially non-hydrophilic layer, and said second substantially non-hydrophilic layer substantially prevents the diffusion of water or medicaments between said first and second hydrophilic layers. ### Claim 23 (depends on 20) A cannula as set forth in claim 20, wherein said first substantially non-hydrophilic layer controls the diffusion rate of water or medicaments between said first hydrophilic layer and said lumen and wherein said second substantially non-hydrophilic layer controls the diffusion rate of water or medicaments between said first hydrophilic layer and the outer surface of said second substantially non-hydrophilic layer.