Patent Application
20120157970
The present disclosure relates to infusion cannulas operable to deliver fluids with a spiral, laminar flow. Particularly, the present disclosure is directed to infusion cannulas operable to infuse fluids having spiral, laminar flow during ocular surgeries.
Cannulas may be used in surgical procedures. For example, cannulas are inserted into a body cavity for infusing or withdrawing fluid therefrom. An infusion cannula may be utilized in ocular surgery to introduce or infuse fluids into the eye, such as to maintain intraocular pressure.
According to one aspect, the disclosure describes an infusion cannula having a body including a first portion defining a first bore and a second portion defining a second bore. The first bore and the second bore are in fluid communication with each other. A passageway may be defined by the first bore and the second bore. The passageway may extend through the body. The cannula may also include a flow-altering device adapted to generate a spiral, laminar flow of fluid passing through the passageway.
The various aspects may include one or more of the following features. The first bore may have a cross-sectional area that is larger than a cross-sectional area of the second bore. The first bore and the second bore may have circular cross-sections, and the first bore may have a larger cross-sectional area than the second bore. The flow-altering device may include a blade disposed at a location in the passageway. The blade may be disposed in the second bore proximate a junction between the first bore and the second bore. The blade may include a leading edge at an upstream location and a trailing edge at a downstream location, and an angle of attack of the leading edge may be less than an angle attack of the trailing edge. The blade may be coupled to an interior wall of the passageway at least one location. The blade may be coupled to the interior wall of the passageway at two locations. The blade may diametrically extend across the passageway. A plurality of blades may be disposed in the passageway. A first portion of the plurality of blades may be disposed in the first bore, and a second portion of the plurality of blades may be disposed in the second bore.
The various aspects may also include one or more of the following features. At least one blade may be radially offset from another blade. The flow-altering device may be a spiral member disposed at a location along the passageway. The spiral member may include a leading edge at an upstream location and a trailing edge at a downstream location. The leading edge may include a first angle of attack and the trailing edge having a second angle of attack. The first angle of attack may be greater than the second angle of attack. An angle of attack of the spiral member may vary from the first angle of attack to the second angle of attack. An angle of attack of the spiral member may decrease from a first angle of attack at a leading edge of the spiral member at an upstream location to a second angle of attack at a trailing edge of the spiral member at a downstream location. An angle of attack of the spiral member may increase from a first angle of attack at a leading edge of the spiral member at an upstream location to a second angle of attack at a trailing edge of the spiral member at a downstream location. The spiral member may have a constant angle of attack along a length thereof. The spiral member may extend through a portion of the first bore and through a portion of the second bore.
The details of one or more implementations of the present disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
The present disclosure is directed to cannulas adapted to generate a spiral, laminar flow therein and expel a diffused flow of fluid from the cannulas. The cannulas described herein may be used in surgical procedures. In some implementations, the cannulas may be used in ophthalmic surgical procedures. The spiral, laminar flow generated in the cannulas provides a reduced pressure drop through the cannula compared to pressure drops associated with turbulent flows. The greater pressure drop generated by turbulent flow also causes a reduction in flow rate. Consequently, the laminar flow may also provide an increased fluid flow rate of fluid exiting the cannula. Additionally, the spiral, laminar flow does not introduce a jet of fluid exiting the cannula that could cause injury to delicate tissues within a patient. Rather, the expelled fluid flow of a spiral, laminar flow is diffuse.
A flow-altering device may be disposed along the passageway 150. For example, the example cannula 110 shown in
Each blade 180 may include a small angle of attack relative to the direction of fluid flow through the passageway 150. In some instances, the angle of attack (interchangeably referred to as “pitch”) of the blade 180 may be constant along a length of the blade 150 parallel with longitudinal axis 145 (“longitudinal length”). In some instances, the angle of attack of blade 180 may increase along the longitudinal length of the blade 150 in the direction of fluid flow. Consequently, the one or more blades 180 are operable to generate a spiral fluid flow within the laminar flow regime. The angles of attack of the blade 180 and the rate at which the angle of attack may change along the longitudinal length of the blade 180 may be selected to control the generation of the laminar, spiral flow.
In some instances, the cannula 110 may include a plurality of blades 180 and a location of one or more of the plurality of blades 180 may be longitudinally staggered along axis 180 from one or more other blades 180. Further, in some instances, one or more blades 180 may be radially offset from one or more other blades 180. In other instances, the cannula 110 may include a plurality of blades 180 in which one or more blades 180 is both longitudinally and radially offset from one or more other blades 180. In some implementations, one or more of the blades 180 may have a constant angle of attack relative to the fluid flow along the longitudinal length of the blade 180. In some instances, the cannula 110 may include one or more blades 180 having different angles of attack and/or one or more blades 180 with a constant angle of attack and/or one or more other blades 180 having a variable angle of attack along a longitudinal length thereof.
As shown in greater detail in
Additionally, while
The angle of attack of the blades (either constant or variable) may be selected based on numerous factors. For example, the angle of attack may be selected based on the flow rate of the fluid through the cannula 110, a viscosity of the fluid, the geometry of the cannula, as well as other factors. Also, while
For the example cannulas 110 shown in
An important aspect of this diffuse flow exiting the example cannula 110 shown in
The baffle 380 may be in the form of an arc-shaped member radially extending from an interior wall 390 of the cannula 310 into the passage 350. The baffle 380 may also have a helical shape such that a baffle 380 extends along a longitudinal distance of the cannula 310. In some instances, the baffle 380 may radially extend along the interior wall 290 approximately 90°. In other instances, the baffle 380 may have a greater or smaller arc length. For example, in some instances, the baffle 380 may have an arc length less than or greater than 90°. Further, in some instances, baffles 380 may be disposed at a same position along a longitudinal length of the cannula 310. In other instances, baffles 380 may be disposed at different locations along the length of the cannula 310. For example, in some instances, two or more baffles 380 may overlap each other by at least a portion thereof. In other instances, a baffle 380 may not longitudinally overlap one or more other baffles 380. The one or more baffles 380 are operable to generate a spiral flow of the fluid passing through the cannula 310 while maintaining the fluid flow in the laminar flow regime.
Additionally, the spiral member 780 may be coupled to an interior wall 790 of passageway 750. For example, the spiral member 780 may be coupled at one or more locations along the length of the spiral member 780. For example, for a spiral member 780 extending into both the first bore 760 and the second bore 770, the spiral member 780 may be coupled to the interior wall 750 at one or more locations in the first bore 760 and at one or more locations within the second bore 770. In other instances, the spiral member 780 may be coupled to the interior wall 750 at one or more locations exclusively in the first bore 760 or the second bore 770. In still other instances, the spiral member 780 may be coupled to the interior wall 790 along an entire length of the spiral member 780. Still further, the spiral member 770 may be coupled to the interior wall 750 at junction 785 between the first bore 760 and the second bore 770.
In some implementations, as shown in
In some instances, the angle of attack of the spiral member 780 may change gradually along a length of the spiral member 780. In some implementations, the angle of attack may change linearly along the length of the spiral member 780, while, in other instances, the angle of attack may change nonlinearly along the length of the spiral member 780. In other implementations, the angle of attack of the spiral member 780 may change linearly along one or more portions of its length and non-linearly along one or more other portions of its length.
In other instances, the spiral member 780 may have a small angle of attack at the first end 712 and a larger angle of attack at the second end 714. Alternately, the angle of attack of the spiral member 780 may increase along only a portion thereof. In still other instances, the angle of attack of the spiral member 780 may progressively increase along portions of the spiral member 780 while other portions of the spiral member 780 may have a constant pitch. Still further, the angle of attack may change linearly or nonlinearly along one or more portions of the length of the spiral member 780. In some instances, the angle of attack of the spiral member 780 may increase linearly along one or more portions, non-linearly along one or more other portions, and, in some instances, include a portion that has a constant angle of attack.
The angle of attack of the spiral member 780 (whether constant or variable over its length) is selected so as to maintain flow in the laminar flow regime. Thus, the pitch of the spiral member 780 may be selected based on one or more factors, such as one or more of the factors described above. Accordingly, the fluid passing through the cannula 710 is formed into a spiral, laminar flow by the spiral member 780 forming a diffuse fluid flow exiting second opening 742. The diffuse flow may significantly reduce or eliminate agitation and/or injury to tissues by avoiding the creation of a jet of fluid exiting the cannula 710.
In some implementations, such as the example cannulas shown in
In
In some instances, as shown in
Further, in regards to one or more of the cannulas described herein, the first bore and the second bore is described as being substantially cylindrical, the bores are not so limited. That is, the first bore and/or the second bore may have a non-cylindrical shape. For example, the first bore and/or the second bore may have a tapered shape.
Referring again to the example cannulas shown in
In some instances, the cannulas described herein may be a 23 gauge, 25 gauge, or 27 gauge cannulas. In still other implementations, one or more of the cannulas described herein may have a larger or smaller gauge sizes. Further, the cannulas may be adapted for use in ophthalmic surgical procedures. However, the cannulas may be used for other surgical procedures, particularly surgical procedures involving the infusion of fluids close to delicate or sensitive tissues.
It should be understood that, although many aspects have been described herein, some implementations may include all of the features, others may include some features while including other, different features, and in still other instances, other implementations may omit some features while including others. That is, various implementations may include one, some, or all of the features described herein.
A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.
