BLOOD COLLECTION SYSTEM WITH AUTOMATIC PRESSURE MANAGEMENT AND RELATED METHODS

Abstract

A blood collection system (10) may include a needle assembly (14), which may include a needle (16) configured to receive a vacuum blood collection tube. The blood collection system (10) may include a tube, which may include a distal end and a proximal end. The proximal end may be coupled to the needle assembly (14). The tube may include a first flow channel (66) and a second flow channel (68). The first flow channel (66) may be configured to collapse at a lower pressure differential than the second flow channel (68).

Description

BLOOD COLLECTION SYSTEM WITH AUTOMATIC PRESSURE MANAGEMENT AND RELATED METHODS BACKGROUND Intravenous catheters are commonly used for various infusion therapies. For example, intravenous catheters can be used to infuse fluids, such as normal saline, various medications, and total parenteral nutrition into a patient. Intravenous catheters can also be used to draw blood from the patient. Common types of intravenous catheters include peripherally inserted central catheters (PICCs), peripherally inserted central catheters (PICCs), and midline catheters. Intravenous catheters may include over-the-needle catheters, which are mounted on a needle with a sharp distal tip. This sharp distal tip can be used to pierce the patient's skin and vasculature. Insertion of the intravenous catheter into the vasculature follows the needle's puncture. The needle and intravenous catheter are typically inserted at a shallow angle through the skin into the patient's vasculature, with the needle bevel facing upward and away from the patient's skin. To verify proper placement of the introducer needle and / or intravenous catheter in the vasculature, a user typically confirms that there is blood backflow, which may be visible to them. In some cases, the introducer needle may include a notch located toward its distal end. In response to the position of the distal tip of the introducer needle within the vasculature, blood may flow proximally through the needle lumen, exit the lumen through the notch, and then migrate proximally between the outer surface of the introducer needle and the inner surface of the intravenous catheter. Therefore, when the intravenous catheter is at least partially transparent, the user can visualize a small amount of blood backflow, thus confirming the catheter's placement within the vasculature. The presence of an indicator of entry into the vasculature, such as backflow, can facilitate successful intravenous catheter placement. Once the placement of the introducer needle within the vasculature has been confirmed, the user can temporarily occlude blood flow and withdraw the needle, leaving the intravenous catheter in place for future blood draws and / or fluid infusions. For blood collection, a vacuum blood collection tube can be used. A vacuum blood collection tube consists of a test tube with a rubber stopper at one end. All or some of the air has been removed from the test tube, so the pressure inside the vacuum blood collection tube is lower than ambient pressure. Such a vacuum blood collection tube is often called an internal vacuum tube or vacuum tube. A commonly used vacuum blood collection tube is the VACUTAINER® blood collection tube, available from Becton, Dickinson & Company. To draw a blood sample from a patient, an adapter is attached to the needle or intravenous catheter. The adapter includes an additional needle that penetrates the rubber stopper of the vacuum blood collection tube. When the stopper is penetrated, the pressure in the vein is higher than the pressure in the vacuum blood collection tube, forcing blood into the tube and filling it. The vacuum inside the vacuum blood collection tube decreases as it fills, until the pressure in the tube equals the pressure in the vein and blood flow stops. Unfortunately, as blood enters the vacuum blood collection tube, the red blood cells are in a state of high shear stress and are susceptible to hemolysis due to a high initial pressure differential between the vein and the vacuum blood collection tube. Hemolysis can lead to rejection and discarding of a blood sample. The high initial pressure differential can also cause catheter tip folding, vein collapse, or other complications that prevent or restrict blood from filling the vacuum blood collection tube. The subject matter claimed herein is not limited to implementations that overcome a disadvantage or operate only in environments such as those described above. Instead, this background information is provided only to illustrate an example technology area where some of the implementations described herein can be practiced. BRIEF DESCRIPTION This disclosure relates generally to an automatically pressure-managed blood collection system and related devices and methods. In some embodiments, a blood collection system may provide a fluid pathway between a catheter and a vacuum blood collection tube, the inner diameter of which responds to a pressure differential between the vacuum blood collection tube and a patient vein. In some embodiments, a pressure differential spike may occur in response to coupling the vacuum blood collection tube to the blood collection system. In some embodiments, in response to the pressure differential spike, the inner diameter of a portion of the fluid pathway may decrease, which may increase the fluid resistance of the fluid pathway and slow blood flow into the blood collection system.In some implementations, decreasing blood flow may reduce the risk of hemolysis. In some implementations, decreasing blood flow may also reduce the risk of vein and / or catheter collapse. In some embodiments, as the vacuum blood collection tube fills with blood, the vacuum inside the tube may decrease, thus reducing the pressure differential between the tube and the vein. In some embodiments, this decreased pressure differential can increase the internal diameter of the fluid pathway portion, which may reduce fluid resistance and increase blood flow into the collection system. Therefore, despite the decreased pressure differential, the vacuum blood collection tube can still fill rapidly. In some embodiments, the blood collection system may include a needle assembly, which may include a needle configured to receive the vacuum blood collection tube. In some embodiments, the blood collection device may include a blood collection tube holder, which may attach to the needle assembly and surround the needle. In some embodiments, the blood collection system may include a tube, which may include a distal end and a proximal end. In some embodiments, the proximal end may attach to the needle assembly. In some embodiments, the tube may include a first flow channel and a second flow channel. In some embodiments, the fluid pathway of the blood collection system may include the first flow channel and the second flow channel. In some embodiments, the first flow channel may be configured to collapse at a lower pressure differential than the second flow channel. In some embodiments, the first flow channel may collapse in response to the peak pressure differential between the vacuum blood collection tube and a patient vein. In some embodiments, the second flow channel may not collapse in response to the peak pressure differential. In some embodiments, because the second flow channel remains open while the first flow channel collapses, the internal diameter may decrease, but the fluid pathway may remain open. In some embodiments, as the vacuum blood collection tube fills with blood, the first flow channel may open, allowing the blood flow rate to increase. In some embodiments, the fluid resistance of the first flow channel may be lower than the fluid resistance of the second flow channel. In these embodiments, the fluid resistance of the first flow channel may be lower than the fluid resistance of the second flow channel because the size or diameter of the first flow channel may be larger than the size or diameter of the second flow channel. In some embodiments, the first flow channel may consist of a first wall and a shared wall that may be shared by the first and second flow channels. In some embodiments, the second flow channel may consist of a second wall and the shared wall. In some embodiments, the first wall may have a lower hardness than the second wall. In some embodiments, the second flow channel may have a drilled orifice.In some embodiments, the perforated hole may extend from the distal end of the tube to the proximal end of the tube. In some embodiments, the blood collection system may include a catheter assembly. In some embodiments, the catheter assembly may include a catheter adapter, which may include a distal end, a proximal end, and a lumen extending through the distal end of the catheter adapter and the proximal end of the catheter adapter. In some embodiments, the distal end of the tubing may be coupled to the catheter adapter. In some embodiments, the catheter assembly may include the catheter extending distally from the distal end of the catheter adapter. In some embodiments, the blood collection system may include a male Luer adapter coupled to the distal end of the tubing and a female Luer adapter coupled to the proximal end of the tubing. In some embodiments, the catheter assembly may be replaced by a needle set, which can be coupled to the distal end of the tubing. In some embodiments, the blood collection system may include an outer tube and an inner tube. In some embodiments, the inner diameter of the outer tube may be larger than both the outer and inner diameters of the inner tube. In some embodiments, the blood collection system may include a first flow channel and a second flow channel. In some embodiments, the first flow channel may extend between the outer and inner tubes. In some embodiments, the second flow channel may extend through the inner tube. In some embodiments, the first flow channel may be configured to collapse at a different pressure differential than the second flow channel. In some embodiments, the outer tube may have a lower hardness than the inner tube. In some embodiments, the other first flow channel may be configured to collapse at a lower pressure differential than the other second flow channel. In some embodiments, at the lower pressure differential, the outer tube may contact the inner tube to close at least a portion of the other first flow channel. oracnn / zznz / E / YiAi In some embodiments, the outer tube may have a higher hardness than the inner tube. In these and other embodiments, the second flow channel may be configured to collapse at a lower pressure differential than the first flow channel. In some embodiments, the distal end of the inner tube may include a duckbill valve. In some embodiments, the blood collection system may include another tube, which may include no more than one flow channel. In some embodiments, the inner surface of the other tube may include one or more ribs or one or more slots. In some embodiments, in response to the peak pressure differential, the slots may close and the flow channel may remain open. In some embodiments, the slots may be configured to close when the pressure differential reaches a predetermined level. In some embodiments, the ribs may extend the length of the other tube and may generally be evenly spaced around the circumference of the inner surface. In some embodiments, the slots may extend outward from a generally cylindrical portion of the fluid channel.In some embodiments, in response to the peak pressure differential, once the pressure differential reaches the predetermined level, the generally cylindrical portion of the fluid channel may remain open. It should be understood that both the preceding general description and the following detailed description are illustrative and explanatory and are not restrictive of the invention as claimed. It should be understood that the various embodiments are not limited to the arrangements and instruments shown in the drawings. It should also be understood that the embodiments may be combined or that other embodiments may be used, and that structural changes, unless otherwise claimed, may be made without departing from the scope of the various embodiments of the present invention. The following detailed description should therefore not be taken in a limiting sense. BRIEF DESCRIPTION OF THE VARIOUS VIEWS OF THE DRAWINGS The illustrative realizations will be described and explained in additional specificity and detail by means of the accompanying drawings in which: Figure 1A is a top perspective view of an example of a blood collection system, according to some embodiments; Figure 1B is a cross-sectional view along line 1B-1B of Figure 1A, according to some embodiments; Figure 1C is an enlarged cross-section of an illustrative tube, according to some embodiments; Figure 1D is a cross-sectional view of the blood extraction system of oracnn / zznz / E / YiAi Figure 1A, according to some embodiments; Figure 2A is another cross-sectional view along line 1B-1B of Figure 1A, according to some realizations; Figure 2B is an enlarged cross-section of another illustrative tube, according to some embodiments; Figure 2C is another cross-sectional view of the blood collection system of Figure 1A, according to some embodiments; Figure 2D is another cross-sectional view of the blood collection system of Figure 1A, which illustrates an example of a closed-ended flow channel, according to some embodiments; Figure 3A is another cross-sectional view along line 1B-1B of Figure 1A, according to some realizations; Figure 3B is an enlarged cross-section of another illustrative tube, according to some embodiments; Figure 3C is another cross-sectional view of the blood collection system of Figure 1A, according to some embodiments; Figure 3D is another cross-sectional view of the blood collection system of Figure 1A, which illustrates an example of a vacuum blood collection tube coupled to the blood collection system, according to some embodiments; Figure 3E is another cross-sectional view of the blood collection system of Figure 1A, according to some embodiments; Figure 4A is another cross-sectional view along line 1B-1B of Figure 1A, according to some realizations; Figure 4B is an enlarged cross-section of another illustrative tube, according to some embodiments; Figure 4C is another cross-sectional view of the blood collection system of Figure 1A, according to some embodiments; Figure 4D is another cross-sectional view of the blood collection system of Figure 1A, illustrating the vacuum blood collection tube coupled to the blood collection system, according to some embodiments; Figure 5A is another cross-sectional view along line 1B-1B of Figure 1A, according to some realizations; Figure 5B is another cross-sectional view of the blood collection system of Figure 1A, according to some embodiments; Figure 6A is a cross-sectional view of another example of a tube at a first pressure differential, according to some embodiments; Figure 6B is a cross-sectional view of the tube in Figure 6A at a second pressure differential, higher than the first pressure differential, according to some embodiments; Figure 7A is a cross-sectional view of another example of a tube at a first pressure differential, according to some embodiments; Figure 7B is a cross-sectional view of the tube in Figure 7A at a second pressure differential, higher than the first pressure differential, according to some embodiments; Figure 8A is a cross-sectional view of another example of a tube at a first pressure differential, according to some embodiments; Figure 8B is a cross-sectional view of the tube in Figure 8A at a second pressure differential, higher than the first pressure differential, according to some embodiments; Figure 9A is a cross-sectional view of another example of a tube at a first pressure differential, according to some embodiments; Figure 9B is a cross-sectional view of the tube in Figure 9A at a second pressure differential, higher than the first pressure differential, according to some embodiments; Figure 10A is a cross-sectional view of another example of a tube at a first pressure differential, according to some embodiments; Figure 10B is a cross-sectional view of the tube in Figure 10A at a second pressure differential, higher than the first pressure differential, according to some embodiments; Figure 11A is a cross-sectional view of another example of a tube at a first pressure differential, according to some embodiments; Figure 11B is a cross-sectional view of the tube in Figure 11A at a second pressure differential, higher than the first pressure differential, according to some embodiments; Figure 12A is another cross-sectional view of the blood collection system of Figure 1A, according to some embodiments; Figure 12B is another cross-sectional view of the blood collection system of Figure 12A, illustrating the vacuum blood collection tube coupled to the blood collection system, according to some embodiments; Figure 12C is a cross-sectional view of another example of a tube at a first pressure differential, according to some embodiments; Figure 12D is a cross-sectional view of the tube in Figure 12C at a second pressure differential, higher than the first pressure differential, according to some embodiments; Figure 13A is a cross-sectional view of another blood collection system, according to some embodiments; Figure 13B is another cross-sectional view of the blood collection system of Figure 13A, illustrating the vacuum blood collection tube coupled to the blood collection system, according to some embodiments; Figure 14 is a cross-sectional view of the blood collection system of Figure 13A, according to some embodiments; Figure 15A is a cross-sectional view of the blood extraction system of Figure 13A at a first pressure differential, according to some embodiments; Figure 15B is a cross-sectional view of the blood extraction system of Figure 15A at a second pressure differential, higher than the first pressure differential, according to some embodiments; Figure 16A is a cross-sectional view of the blood extraction system of Figure 13A at a first pressure differential, according to some embodiments; Figure 16B is a cross-sectional view of the blood collection system of Figure 16A at a second pressure differential, higher than the first pressure differential, according to some embodiments; and Figure 17 is a cross-sectional view of the blood collection system of Figure 13A, according to some embodiments. DESCRIPTION OF THE ACHIEVEMENTS With reference to Figures 1A-1D, in some embodiments, a blood collection system 10 can provide a fluid pathway between a catheter 12 and a vacuum blood collection tube, which has an inner diameter that responds to a pressure differential between the vacuum blood collection tube and a patient vein. In some embodiments, a spike in the pressure differential can occur in response to coupling the vacuum blood collection tube with the blood collection system 10. In some embodiments, in response to the pressure differential spike, the inner diameter of a portion of the fluid pathway can decrease, which can increase the fluid resistance of the fluid pathway and slow blood flow into the blood collection system 10. In some embodiments, the decreased blood flow can reduce the risk of hemolysis.In some implementations, the decrease in blood flow can also reduce the risk of vein and / or catheter collapse. In some embodiments, the vacuum blood collection tube can be evacuated so that the pressure inside the vacuum blood collection tube is lower than ambient or atmospheric pressure. In some embodiments, the vacuum blood collection tube can include any suitable vacuum blood collection tube. In some embodiments, as the vacuum blood collection tube fills with blood, the vacuum inside the vacuum blood collection tube may decrease, and the pressure differential between the vacuum blood collection tube and the vein may decrease. In some embodiments, the decreased pressure differential may result in an increase in the inner diameter of the fluid pathway portion, which may reduce fluid resistance and increase blood flow to the blood collection system.Therefore, despite the decrease in pressure differential, the vacuum blood collection tube can still fill quickly. In some embodiments, the blood collection system 10 may include a needle assembly 14, which may include a needle 16 configured to receive the vacuum blood collection tube (see, for example, Figure 3D). In some embodiments, the needle assembly 14 may include one or more threads, which may be configured to engage a blood collection tube holder 18, which is generally cylindrical. In some embodiments, the blood collection tube holder 18 may surround the needle 16. In some embodiments, the needle assembly 14 may include a luer-lock access device such as, for example, the VACUTAINER® LUER-LOK™ ACCESS DEVICE available from Becton, Dickinson & Company. In some embodiments, needle assembly 14 may include a luer adapter 20, which may include a luer lock connector or a luer slip connector. In some embodiments, the luer adapter 20 may include a male or female luer connector. In some embodiments, needle 16 may extend proximally from the luer adapter 20. In some embodiments, the blood collection system 10 may include a tube 22, which may include a distal end 24 and a proximal end 26. In some embodiments, the proximal end 26 may be coupled to the needle assembly 14, such as, for example, the luer adapter 20 of the needle assembly 14. In some embodiments, the tube 22 may include a first flow channel 28 and a second flow channel 30. In some embodiments, the fluid pathway of the blood collection system 10 may include the first flow channel 28 and the second flow channel 30. In some embodiments, the tube 22 may be made of urethane (including polyurethanes), rubber, polyvinyl chloride (PVC), silicone, polyethylene (low and high density), nylon, fluoropolymers, polypropylene, acrylonitrile butadiene styrene (ABS), polycarbonate, acrylic, and / or similar. In some embodiments, the first flow channel 28 may be configured to collapse at a lower pressure differential than the second flow channel 30. In some embodiments, collapse may involve partial or complete blockage of a particular flow channel due to the failure or collapse of a surrounding wall that forms that particular flow channel. In some embodiments, the first flow channel 28 may collapse in response to the peak pressure differential between the vacuum blood collection tube and the patient's vein. In some embodiments, when the first flow channel 28 collapses, it may become partially or completely blocked. In some embodiments, the second flow channel 30 may not collapse in response to the peak pressure differential, and its diameter may remain the same.In other embodiments, the second flow channel 30 may partially collapse in response to the peak pressure differential. In other embodiments, the second flow channel 30 may collapse less than the first flow channel 28 in response to the peak pressure differential. In some embodiments, because the second flow channel 30 remains open but the first flow channel collapses, the internal diameter of the fluid pathway portion may decrease, but the fluid pathway may remain open. In some embodiments, as the vacuum blood collection tube fills with blood and the pressure differential decreases, the first flow channel 28 may open, allowing the blood flow rate to increase. In some embodiments, the fluid resistance of the first flow channel 28 may be less than the fluid resistance of the second flow channel. In these embodiments, the fluid resistance of the first flow channel 28 may be less than the fluid resistance of the second flow channel 30 because the size or diameter of the first flow channel 28 may be larger than the size or diameter of the second flow channel 30. In some embodiments, the first flow channel 28 may consist of a first wall 32 and a shared wall 34 that may be shared by the first flow channel 28 and the second flow channel 30. In some embodiments, the shared wall 34 may include any portion of the tube 22 disposed between the first flow channel 28 and the second flow channel 30. In some embodiments, the second flow channel 30 may consist of a second wall 36 and the shared wall 34. In some embodiments, the first wall 32 may have a lower hardness than the second wall 36 and / or the shared wall 34. oracnn / zznz / E / YiAi In some embodiments, the second flow channel 30 may have a perforated orifice, as illustrated, e.g., in Figures 1B-1D. In some embodiments, the perforated orifice may extend from the distal end 24 of tube 22 to the proximal end 26 of tube 22. In some embodiments, the perforated orifice may extend along most of the length of tube 22 between the distal end 24 of tube 22 and the proximal end 26 of tube 22. In some embodiments, the perforated orifice may extend along a portion of the length of tube 22 between the distal end 24 of tube 22 and the proximal end 26 of tube 22. In some embodiments, the first flow channel 28 may have a generally circular shape, with the shared wall 34 projecting inward and toward the center of the circle to assume a general C-shape.In some embodiments, the shared wall 34 may be convex and extend into a middle portion of the first flow channel 28. In some embodiments, the blood collection system 10 may include a catheter assembly 40. In some embodiments, the catheter assembly 40 may include a catheter adapter 42, which may include a distal end 44, a proximal end 46, and a lumen 48 extending through the distal end 44 of the catheter adapter 42 and the proximal end 46 of the catheter adapter 42. In some embodiments, the distal end 24 of tubing 22 may be coupled to the catheter adapter 42. In some embodiments, the catheter assembly 40 may include a catheter 12 extending distally from the distal end 44 of the catheter adapter 42. In some embodiments, the catheter assembly 40 may be replaced by a needle set, which may be coupled to the distal end 24 of tubing 22. In some embodiments, the blood collection system 10 may include a Luer adapter 50 attached to the distal end 24 of tube 22 and / or a Luer adapter 52 attached to the proximal end 26 of tube 22. In some embodiments, the Luer adapter 50 and / or the Luer adapter 52 may include a Luer-lock or Luer-slip connector. In some embodiments, the Luer adapter 50 and / or the Luer adapter 52 may include a male or female Luer connector. In some embodiments, the proximal end 26 of tube 22 may be integrated with the Luer adapter 20 and / or the needle assembly 14. In some embodiments, catheter assembly 40 may include a PIVC such as, for example, the BD NEXIVA™ Closed Intravenous Catheter System, the BD CATHENA™ Catheter System, the BD VENFLON™ Pro Safety-Shielded Intravenous Catheter System, the BD NEOFLON™ Intravenous Cannula System, the BD INSYTE™ AUTOGUARD™ BC Shielded Intravenous Catheter System, or another suitable peripheral intravenous catheter system. In some embodiments, catheter assembly 40 may include a PICC or a midline catheter. In some embodiments, luer adapter 50 may be attached to catheter adapter 42 of oracnn / zznz / E / YiAi in several suitable ways. For example, the Luer 50 adapter can be attached to the distal end 44 of the catheter adapter 42. As a further example, the Luer 50 adapter can be attached to an extension tube that extends outward from the catheter adapter 42. In some embodiments, an elastomeric sheath 54 can be attached to the needle assembly 14. In some embodiments, a proximal end 56 of the needle 16 can be covered by the elastomeric sheath 54. In some embodiments, the elastomeric sheath 54 can include an open distal end 58 and a closed proximal end 60. In some embodiments, in response to the pressure of the vacuum blood collection tube on the distal elastomeric sheath 54, the needle 16 can pierce the elastomeric sheath 54 and be inserted into a cavity of the vacuum blood collection tube. With reference now to Figures 2A-2D, in some embodiments, the shape of the first flow channel 28 and / or the second flow channel 30 may vary. In some embodiments, the first flow channel 28 may be formed by the first wall 32 and the shared wall 34, as illustrated, for example, in Figure 2B. In some embodiments, the second flow channel 30 may be formed by the second wall 36 and the shared wall 34, as illustrated, for example, in Figure 2B. In some embodiments, the first wall 32 may have a lower hardness than the second wall 36 and / or the shared wall. In some embodiments, the shared wall 34 may be convex with respect to the first flow channel 28. In some embodiments, the first flow channel 28 and the second flow channel 30, together, may have a generally circular shape.In some embodiments, one or more of the first wall 32, the shared wall 34 and the second wall 36 may generally be smooth. In some embodiments, as illustrated in Figure 2D, the second flow channel 30 may be isolated from the fluid pathway of the blood collection system 10 and may contain air, which can facilitate the collapse or reduction in size of the first flow channel 28 in response to the peak pressure differential. In these embodiments, the ends of the second flow channel 30 may be closed or sealed. With reference now to Figures 3A-4D, in some embodiments, the blood collection system 10 may include an outer tube 62 and an inner tube 64. In some embodiments, the inner diameter of the outer tube 62 may be larger than the inner and outer diameters of the inner tube 64. In some embodiments, the outer tube 62 may include a first flow channel 66, and the inner tube 64 may include a second flow channel 68. In some embodiments, the first flow channel 66 may extend between the outer tube 62 and the inner tube 64. In some embodiments, the second flow channel 68 may extend through the inner tube 64, and the first flow channel 66 may extend through the outer tube 62. oracnn / zznz / E / YiAi In some embodiments, the first flow channel 66 and the outer tube 62 may be configured to collapse at a different pressure differential than the second flow channel 68 and the inner tube 64. With reference now to Figures 3A-3E, in some embodiments, the outer tube 62 may have a lower hardness than the inner tube 64. In some embodiments, the first flow channel 66 and the outer tube 62 may be configured to collapse at a lower pressure differential than the second flow channel 68 and the inner tube 64. In some embodiments, at the lower pressure differential, the outer tube 62 may make contact with the inner tube 64 to close at least a portion of the first flow channel 66. In some embodiments, the first flow channel 66 and the outer tube 62 may collapse in response to the coupling of the vacuum blood collection tube with the blood collection system 10, as illustrated, for example, in Figure 3D. In some embodiments, in response to the vacuum blood collection tube becoming partially filled with blood, the first flow channel 66 may open. In some embodiments, the diameter of the second flow channel 68 may remain the same or substantially the same before and after coupling the vacuum blood collection tube to the blood collection system 10. In some embodiments, the diameter of the second flow channel 68 may remain the same before and after coupling the partially blood-filled vacuum blood collection tube. In some embodiments, the inner tube 64 may not be coupled to the outer tube 62. In some embodiments, the inner tube 64 may be coupled to the outer tube 62. In some embodiments, a portion of the inner tube 64 may be embedded in the outer tube 62. In some embodiments, the inner tube 64 may be secured within the outer tube 62 by a portion of a particular adapter, as illustrated, for example, in Figure 3E. In some embodiments, the second flow channel 68 may be isolated from the fluid path of the blood collection system 10 and may contain air, similarly, for example, to Figure 2D. In some embodiments, the proximal end of the inner tube 64 and / or the outer tube 62 may be integrated with the luer adapter 20 and / or the needle assembly 14. With reference to Figures 4A-4D, in some embodiments, the outer tube 62 may have a higher hardness than the inner tube 64. In some embodiments, the second flow channel 68 and the inner tube 64 may be configured to collapse at a lower pressure differential than the first flow channel 66 and the outer tube 62. In some embodiments, the second flow channel 68 and the inner tube 64 may collapse in response to the coupling of the vacuum blood collection tube with the blood collection system 10, as illustrated, for example, in Figure 4D. In some embodiments, in response to the vacuum blood collection tube becoming partially filled with blood, the second flow channel 68 may open. In some embodiments, the diameter of the first flow channel 66 may remain the same before and after coupling the vacuum blood collection tube with the blood collection system 10.In some embodiments, the diameter of the first flow channel 66 may remain the same before and after attaching the partially blood-filled vacuum blood collection tube. In some embodiments, the second flow channel 68 may be isolated from the fluid path of the blood collection system 10 and may contain air, similarly, for example, to Figure 2D. With reference to Figures 12A-12B, in some embodiments, the distal end of the inner tube 64 may include a duckbill valve 70. In these and other embodiments, the outer tube 62 may have a higher hardness than the inner tube 64. In some embodiments, the second flow channel 68 and the inner tube 64 may collapse in response to the coupling of the vacuum blood collection tube with the blood collection system 10, as illustrated, for example, in Figures 12B and 12D. In some embodiments, in response to the collapse of the second flow channel 68 and the inner tube, the duckbill valve 70 may close. In some embodiments, in response to the vacuum blood collection tube becoming partially filled with blood, the duckbill valve 70 and the second flow channel 68 may open, as illustrated, for example, in Figure 12C. Referring back to Figures 5A-5B, in some embodiments, the tube 22 may include no more than one flow channel 71 extending through the tube 22. In some embodiments, an inner surface of the tube 22 may include one or more ribs 72, as illustrated, for example, in Figures 5A-5B. In some embodiments, the ribs 72 may extend the length of the tube 22 and / or may be generally evenly spaced around the circumference of the inner surface of the tube 22. In some embodiments, the ribs 72 may maintain a minimum flow rate through the tube 22 even when the tube 22 is collapsed. In some embodiments, the outer tube 62 and / or the inner tube 64 described with respect to Figures 3A-4D and 12 may include the ribs 72. With reference now to Figures 6A-8B, in some embodiments, the inner surface of the tube 22 may include one or more slots 74, as illustrated, for example, in Figures 6A-8B. In some embodiments, the tube 22 may include a flow channel 71. In some embodiments, the slots 74 may extend along the length of the tube 22 and / or may generally be evenly spaced around the circumference of the inner surface of the tube 22. In some embodiments, the inner surface of the tube 22 may include one slot, two slots, three slots, four slots, or more than four slots, depending, for example, on the desired flow rate change. In some embodiments, in response to the peak pressure differential, tube 22 may collapse, closing the slots 74 and leaving the flow channel 71 open. For example, in response to coupling the vacuum blood collection tube with the blood collection system 10, tube 22 may collapse. In some embodiments, the slots 74 may extend outward from a generally cylindrical portion 76 of the flow channel 71. In some embodiments, in response to the peak pressure differential, once the pressure differential reaches a predetermined level, the generally cylindrical portion 76 of the fluid channel may remain open. In some embodiments, in response to the vacuum blood collection tube becoming partially filled with blood, the slots 74 may reopen. With reference now to Figures 9A-9B, tube 22 can generally be shaped like an hourglass, such that its medial portion has a smaller outer and inner diameter than either of its sides. In some embodiments, in response to the peak pressure differential, once the pressure differential reaches a predetermined level, tube 22 can collapse, closing the medial portion and forming two flow channels 78, 80, as illustrated, for example, in Figure 9B. In some embodiments, in response to the vacuum blood collection tube becoming partially filled with blood, the medial portion can reopen. With reference to Figures 10A-10B, the cross-section of the inner lumen of tube 22 can generally adopt an hourglass shape, such that a medial portion of the inner lumen has a smaller diameter than either side of the inner lumen. In some embodiments, in response to the peak pressure differential, once the pressure differential reaches a predetermined level, tube 22 can collapse, closing off the medial portion and forming one or more flow channels. For example, in response to the peak pressure differential, once the pressure differential reaches a predetermined level, tube 22 can collapse, closing off the medial portion and forming two flow channels 78, 80, as illustrated, for example, in Figure 10B. In some embodiments, in response to the vacuum blood collection tube becoming partially filled with blood, the medial portion can reopen. With reference to Figures 11A-11B, the first flow channel 28 and the second flow channel 30 are illustrated according to several embodiments. In some embodiments, the first flow channel 28 may be configured to collapse at a lower pressure differential than the second flow channel 30. In some embodiments, the first flow channel 28 may collapse in response to the peak pressure differential between the vacuum blood collection tube and the patient's vein. In some embodiments, when the first flow channel 28 collapses, it may become partially or completely blocked. In some embodiments, the first flow channel 28 may be elongated and have a narrower inner diameter along its entire length compared to the second flow channel 30, which may facilitate the collapse of the first flow channel 28.In some embodiments, the second flow channel 30 can generally be circular or of another suitable shape. With reference to Figures 13A-13B, in some embodiments, a blood collection system 82 may include a housing 84. In some embodiments, the blood collection system 82 may be similar or identical to the blood collection system 10 discussed in Figures 1A-12D in terms of one or more included features and / or operation. In some embodiments, the housing 84 may include a distal end 86 and a proximal end 88. In some embodiments, the housing 84 may correspond to a tube. In some embodiments, the distal end 86 may include a Luer adapter 87 and / or the proximal end 88 may include a Luer adapter 89. In some embodiments, the Luer adapter 87 and / or the Luer adapter 89 may include a Luer-lock or Luer-slip connector. In some embodiments, the Luer adapter 87 and / or the Luer adapter 89 may include a male or female Luer connector.In some embodiments, the proximal end 88 may be integrated with the luer adapter 20 and / or the needle assembly 14. In some embodiments, the blood collection system 82 may include a tube 90, which may include a distal end 92 and a proximal end 94. In some embodiments, the tube 90 may be similar or identical to the tube 22 discussed in Figures 1A-2C and 5A11B in terms of one or more included features and / or operation. In some embodiments, the distal end 92 and / or the proximal end 94 may be coupled to the housing 84. In some embodiments, the housing 84 may have a higher hardness than the tube 90. In some embodiments, in response to the peak pressure differential, as the pressure differential reaches a predetermined level, a flow channel 96 extending through the tube 90 may collapse, as illustrated, for example, in Figure 13B. In some embodiments, the flow channel 96 may be closed or restricted in response to the collapse of the tube 90.In some embodiments, in response to the vacuum blood collection tube becoming partially filled with blood, flow channel 96 may reopen. With reference to Figure 14, in some embodiments, a partition 98 may be arranged within the housing 84. In some embodiments, a flow channel or opening 100 may extend through the partition 98. In some embodiments, the partition 98 may be annular. In some embodiments, a user may manually adjust the diameter of the opening 100. In some embodiments, the partition 98 may be coupled to a threaded nut, which may be screwed into the housing 84. In some embodiments, the threaded nut may be rotated with respect to the housing 84 to increase or decrease the diameter of the opening 100 extending through the partition 98. With reference now to Figures 15A-16B, in some embodiments, the partition 98 within the housing 84 may be partially pressurized with nitrogen or another compressible gas. In some embodiments, in response to the peak pressure differential, the opening 100 may narrow or close due to the presence of the nitrogen or other gas and the expansion of the partition 98. In some embodiments, an internal surface of the partition 98 may include two opposing arc shapes or another suitable shape. As illustrated in Figures 15A-15B, in some embodiments, the partition 98 may not be in contact with the housing 84 along its entire length. In some embodiments, the partition 98 may be coupled to the housing 84 at a first and a second point, and a region between the first and second points may be separated from the housing 84. In some embodiments, this region may be arc-shaped or another suitable shape.As illustrated in Figures 16A-16B, in some embodiments, the partition 98 can make contact with the housing 84 along the entire length of the partition 98. With reference to Figure 17, the tube 90 may be shaped to facilitate a Coanda effect. In some embodiments, the tube 90 may include a first branch 102, which may generally be straight or parallel to the longitudinal axis of the blood collection system 82. Some embodiments may be configured so that the blood within the first branch 102 flows from distal to proximal. In some embodiments, a second branch 104 may extend from the first branch 102. In some embodiments, a portion of the second branch 104 adjacent to the first branch 102 may include a reverse branch, configured so that the blood flows from proximal to distal. In some embodiments, the distal end of the first branch 102 may extend through the distal end 86 of the housing 84 and / or be coupled with the luer adapter 87.In some embodiments, the proximal end of the first branch 102 and / or the proximal end of the second branch 104 can be coupled to the proximal end 88 of the housing 84 and / or to the luer adapter 89. In some embodiments, in response to a high pressure differential or peak pressure differential, blood traveling through tube 90 from catheter assembly 40 can largely bypass the second branch 104. In some embodiments, in response to a high pressure differential or peak pressure differential, most of the blood traveling through tube 90 from catheter assembly 40 can largely bypass the second branch 104 and flow through the first branch 102. In some embodiments, as the pressure differential decreases, more blood can flow through the second branch 104, reducing the overall resistance to flow. All examples and conditional language listed herein are for pedagogical purposes to assist the reader in understanding the invention and the concepts contributed by the inventor to further the technique, and should be considered without limitation to the specifically listed examples and conditions. Although embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations may be made without departing from the spirit and scope of the invention.

Claims

1. A blood collection system, comprising: a needle assembly, comprising a needle configured to receive a vacuum blood collection tube; a tube, comprising a distal end and a proximal end, wherein the proximal end is coupled to the needle assembly, wherein the tube comprises a first flow channel and a second flow channel, wherein the first flow channel is configured to collapse at a lower pressure differential than the second flow channel.

2. The blood extraction system of claim 1, wherein the fluid resistance of the first flow channel may be less than the fluid resistance of the second flow channel.

3. The blood extraction system of claim 2, wherein the first flow channel is formed by a first wall and a shared wall, wherein the second flow channel is formed by a second wall and the shared wall, wherein the first wall has a lower hardness than the second wall.

4. The blood extraction system of claim 3, wherein the second flow channel comprises a perforated orifice extending from the distal end of the tube to the proximal end of the tube.

5. The blood collection system of claim 1, further comprising a blood collection tube holder coupled to the needle assembly, wherein the blood collection tube holder surrounds the needle.

6. The blood collection system of claim 1, further comprising a catheter assembly, wherein the catheter assembly comprises: a catheter adapter, comprising a distal end, a proximal end, and a lumen extending through the distal end of the catheter adapter and the proximal end of the catheter adapter, wherein the distal end of the tube is coupled to the catheter adapter; and a catheter extending distally from the distal end of the catheter adapter.

7. The blood extraction system of claim 1, further comprising a male luer adapter coupled to the distal end of the tube and a female luer adapter coupled to the proximal end of the tube.

8. A blood collection system, comprising: a needle assembly, comprising a needle configured to receive a vacuum blood collection tube; an outer tube, comprising a distal end and a proximal end, wherein the proximal end is coupled to the needle assembly; an inner tube disposed within the outer tube, wherein the inner diameter of the outer tube is greater than the outer diameter of the inner tube; wherein a first flow channel extends between the outer tube and the inner tube; and wherein a second flow channel extends through the inner tube, wherein the first flow channel is configured to collapse at a different pressure differential than the second flow channel.

9. The blood extraction system of claim 8, wherein the outer tube has a lower hardness than the inner tube, wherein the first flow channel is configured to collapse at a lower pressure differential than the second flow channel, wherein at the lower pressure differential, the outer tube makes contact with the inner tube to close at least a portion of the first flow channel.

10. The blood extraction system of claim 8, wherein the outer tube has a greater hardness than the inner tube, wherein the second flow channel is configured to collapse at a lower pressure differential than the second flow channel.

11. The blood extraction system of claim 10, wherein the distal end of the inner tube comprises a duckbill valve.

12. The blood collection system of claim 8, further comprising a blood collection tube holder coupled to the needle assembly, wherein the blood collection tube holder surrounds the needle.

13. The blood collection system of claim 8, further comprising a catheter assembly, wherein the catheter assembly comprises: a catheter adapter, comprising a distal end, a proximal end, and a lumen extending through the distal end of the catheter adapter and the proximal end of the catheter adapter, wherein the distal end of the tube is coupled to the catheter adapter; and a catheter extending distally from the distal end of the catheter adapter.

14. The blood extraction system of claim 8, further comprising a male luer adapter coupled to the distal end of the tube and a female luer adapter coupled to the proximal end of the tube.

15. A blood collection system, comprising: a needle assembly, comprising a needle configured to receive a vacuum blood collection tube; a tube, comprising a distal end and a proximal end, wherein the proximal end is coupled to the needle assembly, wherein the tube comprises no more than one flow channel, wherein an inner surface of the tube comprises a plurality of ribs or a plurality of grooves, wherein, in response to a predetermined pressure differential, the plurality of grooves closes and the flow channel remains open.

16. The blood extraction system of claim 15, wherein the inner surface of the tube comprises the plurality of ribs, wherein the plurality of ribs extend along the length of the tube and are generally evenly spaced around the circumference of the inner surface.

17. The blood extraction system of claim 15, wherein the inner surface of the tube comprises the plurality of grooves, wherein the plurality of grooves extend outwards from a generally cylindrical portion of the fluid channel, wherein, in response to a predetermined pressure differential, the generally cylindrical portion of the fluid channel remains open.

18. The blood collection system of claim 15, further comprising a blood collection tube holder coupled to the needle assembly, wherein the blood collection tube holder surrounds the needle.

19. The blood collection system of claim 15, further comprising a catheter assembly, wherein the catheter assembly comprises: a catheter adapter, comprising a distal end, a proximal end, and a lumen extending through the distal end of the catheter adapter and the proximal end of the catheter adapter, wherein the distal end of the tube is coupled to the catheter adapter; and a catheter extending distally from the distal end of the catheter adapter.

20. The blood extraction system of claim 15, further comprising a male luer adapter coupled to the distal end of the tube and a female luer adapter coupled to the proximal end of the tube.

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