A catheter (100, 200, 300, 400a, 400b) for allowing fluid flow across body structures, including facilitating flow in and out of the body, comprising: an elongate lumen (114, 214, 314, 314a, 314b) extending between a proximal end and a distal end, a diffuser (120, 220, 320, 420a, 420b) coupled to the distal end of the lumen, the diffuser comprising: a flexible upper surface (122, 222, 322) extending radially from the distal end of the lumen when the catheter is in a deployed configuration; a flexible lower surface (124, 224, 324), and an interior portion (128, 228, 328) disposed between the upper and lower surfaces; the interior portion is in fluid communication with the lumen characterized in that: the lower surface (124, 224, 324) forms a conical shape; and the catheter (100, 200, 300, 400a, 400b) further comprises a plurality of walls (125, 126, 225, 325) disposed between and coupled to the upper and lower surfaces, wherein the walls are disposed such that they displace the upper and lower surfaces apart from each other, creating said interior (128, 228, 328) portion, and wherein the walls are thicker toward a center of the diffuser than toward the edges, thus giving the lower surface (124, 224, 324) the conical shape. an elongate lumen (114, 214, 314, 314a, 314b) extending between a proximal end and a distal end, a diffuser (120, 220, 320, 420a, 420b) coupled to the distal end of the lumen, the diffuser comprising: a flexible upper surface (122, 222, 322) extending radially from the distal end of the lumen when the catheter is in a deployed configuration; a flexible lower surface (124, 224, 324), and an interior portion (128, 228, 328) disposed between the upper and lower surfaces; the interior portion is in fluid communication with the lumen characterized in that: the lower surface (124, 224, 324) forms a conical shape; and the catheter (100, 200, 300, 400a, 400b) further comprises a plurality of walls (125, 126, 225, 325) disposed between and coupled to the upper and lower surfaces, wherein the walls are disposed such that they displace the upper and lower surfaces apart from each other, creating said interior (128, 228, 328) portion, and wherein the walls are thicker toward a center of the diffuser than toward the edges, thus giving the lower surface (124, 224, 324) the conical shape. a flexible upper surface (122, 222, 322) extending radially from the distal end of the lumen when the catheter is in a deployed configuration; a flexible lower surface (124, 224, 324), and an interior portion (128, 228, 328) disposed between the upper and lower surfaces; the interior portion is in fluid communication with the lumen characterized in that: the lower surface (124, 224, 324) forms a conical shape; and the catheter (100, 200, 300, 400a, 400b) further comprises a plurality of walls (125, 126, 225, 325) disposed between and coupled to the upper and lower surfaces, wherein the walls are disposed such that they displace the upper and lower surfaces apart from each other, creating said interior (128, 228, 328) portion, and wherein the walls are thicker toward a center of the diffuser than toward the edges, thus giving the lower surface (124, 224, 324) the conical shape. the lower surface (124, 224, 324) forms a conical shape; and the catheter (100, 200, 300, 400a, 400b) further comprises a plurality of walls (125, 126, 225, 325) disposed between and coupled to the upper and lower surfaces, wherein the walls are disposed such that they displace the upper and lower surfaces apart from each other, creating said interior (128, 228, 328) portion, and wherein the walls are thicker toward a center of the diffuser than toward the edges, thus giving the lower surface (124, 224, 324) the conical shape.