Vascular Access System Having Flow Restriction Device - Patent application

Abstract

The vascular access system includes a catheter adapter including a body and a catheter configured to be inserted into a patient's vascular system, a blood collection device in fluid communication with the catheter, the body having a distal end and a proximal end opposite the distal end, and a flow restriction device configured to limit a blood collection rate to a rate equal to or less than a blood supply rate of the patient's blood vessel.

Description

[Technical field]

[0001] The present disclosure relates to a vascular access system having a flow restriction device. [Background technology]

[0002] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 310,894, entitled "Vascular Access System with Flow Restriction Device," filed February 16, 2022, the entire contents of which are incorporated by reference herein.

[0003] (Background technology) Catheters are frequently used to infuse fluids into and out of the body. Patients in various settings, including hospitals and home care, receive fluids, medicines, and blood products through vascular access devices inserted into the patient's vascular system. Catheters of various types and sizes have been widely used in various procedures, including but not limited to treating infections, providing anesthesia or analgesia, providing nutrition, treating cancerous growths, maintaining blood pressure and heart rhythm, and many other clinical applications. A typical vascular access device is a plastic catheter that is inserted into a patient's vein. The length of the catheter may vary from a few centimeters for peripheral access to many centimeters for central access. Typically, catheters are incorporated into a catheter adapter to improve the ease of use, accessibility, and utility of the catheter. The catheter adapter is adapted to receive one end of the catheter, with one end of the catheter supported by the catheter adapter, and the catheter body and tip extend from the first end of the catheter adapter. Typically, the catheter adapter further includes a second end adapted to receive additional infusion components for use with the catheter. For example, the second end of the catheter adapter may include threads for attachment of an intravenous line or connection of a syringe to the catheter adapter, thereby allowing access to the patient's vascular system via the attached catheter.

[0004] The catheter may be inserted percutaneously. When inserted percutaneously, insertion of the catheter is typically assisted by an introducer needle. Typically, the introducer needle is housed within the lumen of the catheter, and the gauge of the needle approximates the inner diameter of the catheter. The needle is positioned within the catheter, with the needle tip extending beyond the tip of the catheter. The needle is then used to penetrate the patient's vein and provide an opening for insertion of the catheter.

[0005] Typically, to confirm proper placement of the introducer needle and / or catheter within the vasculature, the clinician will confirm the presence of a "flashback" of blood in the flashback chamber of the catheter assembly. Once needle placement is confirmed, the clinician can temporarily block flow in the vasculature and remove the needle, leaving the catheter in place for future blood draws, infusions, or probe access. Summary of the Invention [Problem to be solved by the invention]

[0006] Using a catheter to draw blood or administer fluids can be difficult for several reasons, especially if the catheter is left in the patient for more than a day. For example, when a catheter is left in the patient for an extended period of time, the catheter becomes susceptible to stenosis, collapse, kinking, blockage by debris (e.g., fibrin, platelet clots, or thrombus), and adhesion of the catheter tip to the vasculature. For this reason, catheters are often used to draw blood samples at the time of catheterization, but are used less frequently to draw blood samples during the catheterization period. Thus, when a blood sample is required, an additional needle stick is used to provide venous access for the blood draw, which can be painful for the patient and can result in high material costs. [Means for solving the problem]

[0007] In one aspect or embodiment, a vascular access system includes a catheter adapter including a body and a catheter configured to be inserted into a patient's vascular system, and a blood collection device in fluid communication with the catheter, the body having a distal end and a proximal end disposed opposite the distal end, and the blood collection device including a flow restriction device configured to reduce a blood collection flow rate below a blood supply flow rate of the patient's blood vessel.

[0008] The flow restrictor may be a flexible extension set including a tube. The inner diameter and length of the tube may be configured to reduce the blood withdrawal flow rate. The flow restrictor may be configured to reduce the maximum shear stress compared to the maximum shear stress of the catheter.

[0009] The flow restrictor is configured to provide a predetermined reduction in blood draw flow rate by a geometric coefficient G f and G f =L / D 4 where L is the length of the flow restrictor passage and D is the inner diameter of the flow restrictor. The geometric coefficient G f is at least 3.87 x 10 6 From 8.38 x 10 6 The geometric coefficient G f is at least 3.87 x 10 6 The geometric coefficient G f is at least 4.35 x 10 6 The geometric coefficient G f is at least 5.80×10 6 The geometric coefficient G f is at least 8.38×10 6 may be also possible.

[0010] The blood collection device may include a luer lock access device configured to receive an evacuated blood collection container. The blood collection device may include a luer connector configured to connect to a syringe barrel.

[0011] The vascular access system may include an instrument advancement device coupled to the catheter adapter. The instrument advancement device includes an instrument, the instrument advancement device configured to advance the instrument from a retracted position to an advanced position beyond the distal end of the catheter. The vascular access system may include an advancement member configured to be grasped by a medical technician. Movement of the advancement member moves the instrument between the retracted and advanced positions.

[0012] In a further aspect or embodiment, a vascular access system includes a catheter adapter including a body and a catheter configured to be inserted into a patient's vascular system, a first blood draw device configured to be in fluid communication with the catheter, and a second blood draw device configured to be in fluid communication with the catheter, the body having a distal end and a proximal end disposed opposite the distal end, the first blood draw device including a first flow restriction device configured to reduce a blood draw flow rate to a first predetermined blood draw flow rate, and the second blood draw device including a second flow restriction device configured to reduce the blood draw flow rate to a second predetermined blood draw flow rate, the first predetermined blood draw flow rate being greater than the second predetermined blood draw flow rate.

[0013] In a further aspect or embodiment, a method of selecting a blood collection device for use with a catheter adapter including a body and a catheter configured for insertion into a patient's vascular system includes: providing a first blood collection device configured to be in fluid communication with the catheter, the first blood collection device including a first flow restriction device configured to reduce a blood draw rate to a first predetermined blood draw rate; providing a second blood draw device configured to be in fluid communication with the catheter, the second blood draw device including a second flow restriction device configured to reduce a blood draw rate to a second predetermined blood draw rate, the first predetermined blood draw rate being greater than the second predetermined blood draw rate; selecting a first blood collection device or a second blood collection device based on an estimate of the patient's vascular blood supply flow rate; Includes.

[0014] In a further aspect or embodiment, the blood collection device includes a flow restriction device configured to reduce the blood collection rate to be equal to or less than the patient's vascular blood supply rate.

[0015] The flow restricting device may be a flexible extension set including a tube. The inner diameter and length of the tube may be configured to reduce the blood collection flow rate. The flow restricting device may be configured to reduce a maximum shear stress compared to a maximum shear stress of the catheter. The blood collection device may include a luer lock access device configured to receive an evacuated blood collection container. The blood collection device may include a luer connector configured to connect to a syringe barrel.

[0016] The foregoing and other features and advantages of the present disclosure, as well as the manner in which they are achieved, will become more apparent, and the disclosure itself will be better understood, by reference to the following description of the embodiments of the present disclosure in combination with the accompanying drawings, in which: [Brief description of the drawings]

[0017] [Figure 1] 1 is a perspective view of a vascular access system according to one aspect or embodiment of the present application showing a retracted position of an instrument; [Diagram 2] 1 is a perspective view of a vascular access system according to a further aspect or embodiment of the present application showing an advanced position of an instrument; [Diagram 3] 1 is a perspective view of a flow restrictor device according to one aspect or embodiment of the present application. [Figure 4] 1 is a perspective view of a flow restrictor device according to one aspect or embodiment of the present application. [Diagram 5] FIG. 1 is a graph comparing the total blood draw flow rate using a gauge-specific flow restriction device to achieve a 2X reduction in blood draw flow rate for 18G, 20G, 22G, and 24G blood draw needles or catheters with the total blood draw flow rate without a flow restriction device. [Figure 6]This graph compares the sum of maximum shear stress when using gauge-specific flow restrictors to achieve a half reduction in blood collection flow rate for 18G, 20G, 22G, and 24G blood collection needles or catheters (relative to the maximum shear stress of a known 21G blood collection needle) with the sum of blood collection flow rate without using a flow restrictor. [Figure 7] FIG. 1 is a graph comparing the total blood draw flow rate using a gauge-specific flow restriction device to achieve a 3X reduction in blood draw flow rate for 18G, 20G, 22G, and 24G blood draw needles or catheters with the total blood draw flow rate without a flow restriction device. [Figure 8] 1 is a graph showing the sum of maximum shear stress using gauge-specific flow restrictors to achieve a 1 / 3 reduction in blood draw flow rate (compared to the known maximum shear stress of a 21-gauge blood draw needle) for 18-, 20-, 22-, and 24-gauge blood draw needles or catheters, compared to the sum of blood draw flow rates without flow restrictors. [Figure 9] 1 is a graph showing the total blood draw flow rate (as a ratio to the blood draw flow rate of a known 21G blood draw needle) for 18G, 20G, 22G, and 24G blood draw needles or catheters using a gauge-specific flow restrictor to achieve a 1 / 3 reduction in blood draw flow rate for a known 21G blood draw needle, compared to the total blood draw flow rate without a flow restrictor. [Figure 10] This graph compares the sum of maximum shear stress (ratio to the maximum shear stress of a known 21G blood collection needle) when a gauge-specific flow restrictor is used to achieve a 1 / 3 reduction in blood collection flow rate for a known 21G blood collection needle for 18G, 20G, 22G, and 24G blood collection needles or catheters, with the sum of blood collection flow rate without a flow restrictor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set forth herein depict exemplary embodiments of the present disclosure, and such exemplifications are not to be construed as limiting the scope of the present disclosure in any way.

[0019] Spatial or directional terms such as "left", "right", "inside", "outside", "upper", "lower", etc. are not to be construed as limiting, as the invention can contemplate various alternative orientations.

[0020] In the following description, the terms "upper," "lower," "right," "left," "vertical," "horizontal," "top," "bottom," "transverse," "vertical," and derivatives thereof, refer to the invention as oriented in the figures of the drawings. It should be understood, however, that the invention may assume various alternative modifications unless expressly specified to the contrary. It should also be understood that the specific devices illustrated in the accompanying drawings and described in the following specification are merely exemplary aspects of the invention.

[0021] Unless otherwise specified, all ranges or ratios disclosed herein should be understood to include the starting and ending values, and any subranges or subratios subsumed therein. For example, a range or ratio specified as "1 to 10" should be interpreted to include any subrange or subratio between (and including) the minimum value of 1 and the maximum value of 10, i.e., any subrange or subratio beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less.

[0022] The terms "first," "second," and the like do not imply a particular order or chronology, but rather refer to distinct conditions, characteristics, or elements.

[0023] As used herein, "at least one" is synonymous with "one or more." For example, the phrase "at least one of A, B, and C" means any one of A, B, or C, or any combination of two or more of A, B, or C. For example, "at least one of A, B, and C" includes one or more of A alone, one or more of B alone, one or more of C alone, one or more of A and one or more of B, one or more of A and one or more of C, one or more of B and one or more of C, or one or more of all of A, B, and C.

[0024] 1-3, in one aspect or embodiment, a vascular access system 10 includes a catheter assembly 12, which may include a catheter adapter 14 and a catheter 16. The catheter 16 may be a peripheral venous catheter, a peripherally inserted central catheter, or a midline catheter. In some aspects or embodiments, the catheter adapter 14 includes a distal end 18, a proximal end 20, and a lumen extending through the distal end 18 and the proximal end 20. In some aspects or embodiments, the catheter 16 extends distally from the distal end 18 of the catheter adapter 14. The catheter adapter 14 may be integrated with an extension tube 22 that extends from a side port of the catheter adapter 14. In some aspects or embodiments, an adapter 26, such as, for example, a Y-adapter or a T-adapter, may be coupled to the proximal end of the extension tube 22. An instrument advancement device 28 may be coupled to the catheter assembly 12 in a variety of ways. In one aspect or embodiment, the instrument advancement device 28 is coupled to a port of the adapter 26. In one aspect or embodiment, the instrument advancement device 28 is coupled to a needleless connector 29 disposed between the port of the adapter 26 and the instrument advancement device 28. The instrument advancement device 28 may also be coupled to the proximal end 20 of the catheter adapter 14.

[0025] The instrument advancement device 28 may include a housing 30 configured to couple to the catheter assembly 12. The instrument advancement device 28 includes an instrument 32. In some aspects or embodiments, the instrument advancement device 28 may include any suitable delivery device. Some examples of instrument advancement devices that may be used with the instrument 32 include: U.S. Patent Application No. 16 / 037,246, filed July 17, 2018, entitled “EXTENSION HOUSING A PROBE OR INTRAVENOUS CATHETER”; No. 16 / 388,650, filed April 18, 2019, entitled "INSTRUMENT DELIVERY DEVICE HAVING A ROTARY ELEMENT"; No. 16 / 037,319, filed July 17, 2018, entitled “MULTI-DIAMETER CATHETER AND RELATED DEVICES AND METHODS”; U.S. Patent Application No. 16 / 502,541, filed July 3, 2019, entitled "DELIVERY DEVICE FOR A VASCULAR ACCESS INSTRUMENT"; No. 16 / 691,217, filed November 21, 2019, entitled "SYRINGE-BASED DELIVERY DEVICE FOR A VASCULAR ACCESS INSTRUMENT"; No. 62 / 794,437, filed January 18, 2019, entitled “CATHETER DELIVERY DEVICE AND RELATED SYSTEMS AND METHODS”; and U.S. Provisional Patent Application No. 62 / 830,286, filed April 5, 2019, entitled "VASCULAR ACCESS INSTRUMENT HAVING A FLUID PERMEABLE STRUCTURE AND RELATED DEVICES AND METHODS" No. 6,399,623, which are incorporated herein by reference in their entireties.

[0026] In some aspects or embodiments, the instrument advancement device 28 may be configured to introduce the instrument 32 into the catheter assembly 12. In response to the instrument 32 being introduced into the catheter assembly 12, the instrument 32 may access a fluid path of the catheter assembly 12 and / or the instrument 32 may extend through the catheter assembly 12 to access the vascular system of the patient. The instrument advancement device 28 may be configured to advance the instrument 32 between a retracted position, as shown, for example, in FIG. 1 , and an advanced position, as shown, for example, in FIG. 2 . In response to the instrument 32 being in the advanced position, the distal end 34 of the instrument 32 may be disposed distal to the distal end 36 of the catheter 16. In response to the instrument 32 being in the retracted position, the distal end 34 of the instrument 32 may be disposed within the housing 30. The proximal end of the instrument 32 may be coupled to an advancement tab 38. A user may grasp the advancement tab 38 and move it along a slot 40 to move the instrument 32 between the retracted position and the advanced position. The advancement tab 38 may extend through the slot 40 , and the portion of the advancement tab 38 connected to the proximal end of the instrument 32 may be within the housing 30 .

[0027] 1-3, the vascular access system 10 includes a blood collection device 50 in fluid communication with the catheter 16. As described in more detail below, the blood collection device 50 includes a flow restriction device 60 configured to reduce the blood collection flow rate to be equal to or less than the blood supply flow rate of the patient's blood vessel. The blood collection device 50 may be coupled to a port of the adapter 26, or other suitable configurations may be used. During blood collection using the vascular access system 10, such as by using an evacuated blood collection tube (not shown), if the catheter 16 is placed near the end of the patient's arm, the blood supply may be restricted. Similarly, blood flow may be restricted in pediatric patients or patients who are dehydrated. In patients with weakened blood vessels, blood flow restriction during blood collection may cause the blood vessels to collapse. All of these situations may result in difficult or failed blood collection. The flow restriction device 60 of the present application is configured to ensure successful blood collection in patients with restricted blood flow in their vascular system.

[0028] 3, in one aspect or embodiment, the flow restrictor 60 of the blood collection device is a flexible extension set including tubing 62. The blood collection device 50 includes a male luer connector 64 at one end of the tubing 62 and a female luer connector 66 at the other end of the tubing 62. The blood collection device 50 may include a tubing clamp 68. The female luer connector 66 may be connected to a syringe barrel (not shown) or other suitable blood collection container. In certain aspects or embodiments, the flow restrictor 60 is a flexible extension set, a miniature connector with a tortuous flow path, and / or a rigid connector with an elongated fluid path.

[0029] With reference to FIG. 4, in one aspect or embodiment, blood collection device 50 includes a luer lock access device 70 configured to receive an evacuated blood collection container.

[0030] In one aspect or embodiment, the inner diameter and length of the tubing of the flow restrictor 60 is configured to reduce the blood withdrawal flow rate. Also, in one aspect or embodiment, the flow restrictor 60 is configured to reduce the maximum shear stress compared to the maximum shear stress of the catheter 16.

[0031] In one aspect or embodiment, the flow restrictor 60 is configured to provide a predetermined blood draw flow reduction by a geometric factor G f For a simple fluid path, the geometric factor G f is the formula G f =L / D 4 where L is the length of the flow path of the flow restrictor 60 and D is the inner diameter of the flow restrictor 60. Based on the gauge of the catheter or needle, the geometric factor G f The minimum values ​​are shown in Table 1 below.

[0032] [Table 1]

[0033] Fluid flow through a tubular fluid passage is governed by the Poiseuille equation:

[0034]

number

[0035] where ΔP is the change in pressure gradient across the length of the fluid path, D and L are the inner diameter and length of the fluid path, respectively, and μ is the viscosity of the fluid, and is given by the following formula:

[0036]

number

[0037] R calculated as f is the fluid resistance) Since μ is the viscosity of the fluid and is not part of the geometry of the flow restrictor 60, the geometric coefficient G f is R f (fluid resistance)

[0038]

number

[0039] (In the formula, G f =L / D 4 In some aspects or embodiments, the optimized fluid pathway may have multiple sections with lengths (L1, L2, L3) and internal diameters (D1, D2, D3), where the geometric coefficients are:

[0040]

number

[0041] In some aspects or embodiments, the optimized fluid path may have an inner diameter that varies over the length of the tube, with geometric coefficients as follows:

[0042]

number

[0043] In some aspects or embodiments, the optimized fluid path may have a cross-section that is not circular, i.e., has a complex inner diameter profile. By measuring the flow rate (Q) at a given pressure (ΔP) with a known viscosity (μ), the geometric coefficients can be determined as follows:

[0044]

number

[0045] In one aspect or embodiment, the geometric coefficient G of the flow restrictor 60 f and decrease the blood draw rate.

[0046] 5 and 6, by selecting a predetermined geometric coefficient of the flow restrictor 60, the average blood collection flow rate can be reduced by a factor of 2. Furthermore, the maximum shear stress obtained as a ratio to the maximum shear stress of a known 21G blood collection needle (such as the 21G Ultratouch™ blood collection set available from Becton, Dickinson and Company) is equal to or less than the maximum shear stress of a known 21G blood collection needle (except for 24G), thereby indicating a reduced risk of hemolysis.

[0047] 7 and 8, in one aspect or embodiment, a gauge-specific geometric coefficient value can be determined to achieve a 3X reduction in blood collection flow rate, where the maximum shear stress obtained as a ratio to the maximum shear stress of a known 21G blood collection needle (such as a 21G Ultratouch™ blood collection set, available from Becton, Dickinson and Company) is equal to or less than the maximum shear stress of the known 21G blood collection needle.

[0048] 9 and 10, in one aspect or embodiment, gauge-specific geometric coefficient values ​​can be determined to achieve the same blood collection flow rate for all gauges. As shown in FIG. 9, the geometric coefficient value of the flow restrictor can be determined to have a blood collection flow rate that is 1 / 3 lower than that of a known 21G blood collection needle (such as a 21G Ultratouch™ blood collection set available from Becton, Dickinson and Company) in all gauges. As shown in FIG. 10, the maximum shear stress obtained as a ratio to the maximum shear stress of a known 21G blood collection needle (such as a 21G Ultratouch™ blood collection set available from Becton, Dickinson and Company) is equal to or lower than that of a known 21G blood collection needle.

[0049] In one aspect or embodiment, gauge-specific geometric coefficient values ​​are determined for all gauges to achieve the same blood draw flow rate at any desired low flow rate. Similarly, gauge-specific geometric coefficient values ​​can be determined to achieve any desired factor reduction in blood draw flow rate for each gauge.

[0050] In one aspect or embodiment, the vascular access system 10 includes a plurality of blood collection devices, each of which includes a flow restriction device 60 and each of which has a different flow rate. Selecting one of the plurality of blood collection devices based on the patient's condition can enable improved blood collection outcomes. In one aspect or embodiment, a method for selecting a blood collection device 50 for use with a catheter adapter 14 includes: Providing a plurality of blood collection devices 50, each blood collection device 50 including a flow restriction device 60 having a predetermined blood collection flow rate; selecting one of a plurality of blood collection devices 50 based on an estimate of the patient's vascular blood supply flow rate; In one aspect or embodiment, three blood collection devices 50 may be provided having three different blood collection flow rates, with the appropriate blood collection device 50 being selected such that the blood collection flow rate of the blood collection device 50 does not exceed the patient's vascular blood supply flow rate.

[0051] Thus, the blood collection device 50 of the present application is configured to improve the success rate of blood collection when blood flow is restricted. In addition, the blood collection device 50 of the present application is configured to reduce the possibility of blood vessel collapse and improve the success rate of blood collection when the catheter tip is close to a valve or venous wall. Furthermore, the blood collection device 50 of the present application is configured to reduce maximum shear stress and minimize the possibility of hemolysis during blood collection.

[0052] Although the present invention has been described in detail for purposes of illustration based on what are presently considered to be the most practical and preferred embodiments, such details are for this purpose only and the present invention is not limited to the disclosed embodiments. On the contrary, it is to be understood that the present invention is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.

Claims

1. a catheter adapter including a body and a catheter configured to be inserted into a patient's vascular system, the body having a distal end and a proximal end opposite the distal end; a blood collection device in fluid communication with the catheter, the blood collection device including a flow restrictor configured to cause a blood collection rate to be equal to or less than a rate of the patient's vascular blood supply; A vascular access system comprising:

2. The vascular access system of claim 1 , wherein the flow restrictor comprises a flexible extension set including tubing.

3. 3. The vascular access system of claim 2, wherein the inner diameter and length of the tube are configured to reduce blood draw rate.

4. 10. The vascular access system of claim 1, wherein the flow restrictor is configured to reduce a maximum shear stress as compared to a maximum shear stress of the catheter.

5. The flow restrictor has a geometric factor G configured to provide a predetermined blood draw flow reduction. ｆ and G ｆ = L / D ４ 2. The vascular access system of claim 1, wherein L is the length of the flow path of the flow restrictor and D is the inner diameter of the flow restrictor.

6. Geometric coefficient G ｆ is at least 3.87 × 10 ６ From 8.38 x 10 ６ The vascular access system of claim 5 .

7. Geometric coefficient G ｆ is at least 3.87 × 10 ６ The vascular access system of claim 5 .

8. Geometric coefficient G ｆ is at least 4.35 × 10 ６ The vascular access system of claim 5 .

9. Geometric coefficient G ｆ is at least 5.80 x 10 ６ The vascular access system of claim 5 .

10. Geometric coefficient G ｆ is at least 8.38 × 10 ６ The vascular access system of claim 5 .

11. 10. The vascular access system of claim 1, wherein the blood collection device includes a luer lock access device configured to receive an evacuated blood collection container.

12. The vascular access system of claim 1 , wherein the blood collection device includes a luer connector configured to be connected to a syringe barrel.

13. 10. The vascular access system of claim 1, further comprising an instrument advancing device coupled to the catheter adapter, the instrument advancing device including an instrument, the instrument advancing device configured to advance the instrument from a retracted position to an advanced position beyond the distal end of the catheter.

14. 14. The vascular access system of claim 13, further comprising an advancement member configured to be grasped by a medical technician, movement of the advancement member moving the instrument between the retracted position and the advanced position.

15. a catheter adapter including a body and a catheter configured to be inserted into a patient's vascular system, the body having a distal end and a proximal end opposite the distal end; a first blood collection device in fluid communication with the catheter, the first blood collection device including a first flow restriction device configured to reduce a blood collection rate to a first predetermined blood collection rate; a second blood collection device in fluid communication with the catheter, the second blood collection device including a second flow restriction device configured to reduce a blood collection rate to a second predetermined blood collection rate; wherein the first predetermined blood draw rate is greater than the second predetermined blood draw rate.

16. 16. The vascular access system of claim 15, wherein the first flow restriction device comprises a flexible extension set including tubing, and the second flow restriction device comprises a flexible extension set including tubing.

17. 1. A blood collection device comprising: a flow restrictor adapted to restrict the rate at which blood is drawn to less than or equal to the rate at which the patient's vascular blood supply flows.

18. 20. The blood collection device of claim 17, wherein the flow restrictor comprises a flexible extension set including tubing.

19. 20. The blood collection device of claim 18, wherein the inner diameter and length of the tube are configured to reduce blood collection flow rate.

20. 20. The blood collection device of claim 17, wherein the flow restrictor is configured to reduce a maximum shear stress compared to a maximum shear stress of the catheter.

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