Patent Application
20120157969
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 may include a body having a first portion defining a first bore, the first bore having a longitudinal axis, and a second portion defining a second bore. The first bore and the second bore may be in fluid communication with each other. The infusion cannula may also include a passageway passing through the body. A flow tube may define a third bore in fluid communication with the first bore. The third bore may have a longitudinal axis that is angularly offset from the longitudinal axis of the first bore.
Another aspect of the present disclosure includes an infusion cannula including a body having a first bore having a first longitudinal axis, a second bore having a second longitudinal axis, the first bore in fluid communication with the second bore, and a third bore having a third longitudinal axis. The third bore may be in fluid communication with the first bore. The third longitudinal axis may be laterally offset from the first longitudinal axis and angularly offset from the first longitudinal axis.
A further aspect may include an infusion cannula including a first portion defining a first bore, a second portion defining a second bore. The second bore may have a diameter less than a diameter of the first bore, and the first bore and the second bore may be in fluid communication with each other. A first fluid flow may be introduced into the first portion. The first flow may include a flow component perpendicular to a longitudinal axis of the first bore, and the first flow may be introduced into the first bore at a lateral offset from the longitudinal axis of the first bore.
The various aspects may include one or more of the following features. The longitudinal axis of the third bore may be laterally offset from the longitudinal axis from the first bore. An outer surface of the flow tube may be flush with an outer surface of the first portion at a location where a radial line of the first portion extending through the longitudinal axis of the first bore intersects the outer surface of the first portion. The flow tube may be tapered. The angle between the longitudinal axis of the third bore and the longitudinal axis of the first bore may be 90°. The angle between the longitudinal axis of the third bore and the longitudinal axis of the first bore may be less than 90°. A diameter of the third bore may be less than a radius of the first bore. A diameter of the third bore may be one-half of the diameter of the first bore. A first flow may pass through the first bore, and a second flow may pass through the third bore. The first flow and the second flow may intersect to form a spiral, laminar flow, and the spiral, laminar flow may be expelled through an outlet of the second portion.
A fluid flow may be passed through the third bore to form a spiral, laminar flow within the first bore that is expelled through an outlet of the second portion. The longitudinal axis of the third portion is laterally offset from the longitudinal axis of the first portion by a distance of half of the radius of the first portion. A diameter of the third portion at a location where the third portion intersects the first portion may be equal to the radius of the first portion. A diameter of the third portion at a location where the third portion intersects the first portion may be less than the radius of the first portion.
The various aspects may also include one or more of the following features. A first flow may be passing through the first bore, and a second flow may be passing through the third bore to form a spiral, laminar flow. The spiral, laminar flow may be expelled through an outlet formed in the second portion. The first longitudinal axis and the second longitudinal axis may be aligned. A fluid flow may be passed through the third bore to form a spiral, laminar flow within the first bore and expelled through an outlet formed in the second portion. The flow tube may be tapered. A diameter of the third bore may be smaller than a diameter of the first bore. The diameter of the third bore may be one-half of the diameter of the first bore.
The various aspects may further include one or more of the following features. A flow direction of the first fluid flow may be substantially perpendicular to the longitudinal axis of the longitudinal axis of the first bore, the first fluid flow adapted to generate a spiral, laminar flow expelled from an outlet of the second portion. A second fluid flow may be introduced into the first bore, the first fluid flow and the second fluid flow combine to form a spiral, laminar flow expelled from the outlet of the second portion.
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.
