CATHETER EXTENSION SET AND RELATED METHODS.

Abstract

A catheter extension assembly may include a distal end, which may include a Luer adapter configured for coupling with a catheter adapter. The catheter extension may also include a proximal end, which may include a blood collection device. The blood collection device may include a needle configured to receive a blood collection container. The catheter extension may include one or more extension tubes that extend between the distal and proximal ends. The catheter extension assembly can increase flow resistance, which can reduce the risk of hemolysis when there is a high pressure differential within the catheter extension assembly. After reducing the pressure differential within the catheter extension assembly, the catheter extension assembly can decrease flow resistance, which can facilitate faster blood collection.

Description

CATHETER EXTENSION SET AND RELATED METHODS BACKGROUND A catheter is commonly used to infuse fluids into a patient's vasculature. For example, a catheter can be used to infuse normal saline, various medications, or total parenteral nutrition. A catheter can also be used to draw blood from the patient. The catheter may include a peripheral intravenous (IV) catheter that covers the needle. In this case, the catheter may be mounted on an introducer needle with a sharp distal tip. The catheter and introducer needle may be assembled so that the distal tip of the introducer needle extends beyond the distal tip of the catheter, with the bevel of the needle facing upward and away from the patient's skin. The catheter and introducer needle are typically inserted at a shallow angle, through the skin, into the patient's vasculature. To verify proper placement of the introducer needle and / or catheter in the blood vessel, a physician typically confirms that blood flows back into a return chamber of the catheter assembly. Once needle placement is confirmed, the physician can temporarily occlude flow in the vasculature and remove the needle, leaving the catheter in place for future blood draws or fluid infusions. A blood collection container can be used to draw blood or collect a blood sample from a patient. The blood collection container may consist of a syringe or a test tube with a rubber stopper at one end. In some cases, the air inside the blood collection container has been partially or completely removed from the test tube, so the pressure within the container is lower than ambient pressure. Such a blood collection container is often called an internal vacuum tube or vacuum tube. One commonly used blood collection container is the VACUTAINER® blood collection tube, marketed by Becton Dickinson & Company. The blood collection container can be attached to the catheter. When the blood collection container is attached to the catheter, the pressure in the vein is higher than the pressure in the blood collection container, forcing blood into the container and filling it. The vacuum inside the blood collection container decreases as it fills, until the pressure in the container equals the pressure in the vein and blood flow stops. Unfortunately, as the blood enters the blood collection container, MA / a / ¿U¿¿ / UU l ¿40 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 blood collection container. 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 blood collection container. As the blood collection container fills, the pressure differential between the vein and the blood collection container decreases, and filling of the blood collection tube slows significantly. 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 area of ​​technology where some of the implementations described herein can be put into practice. BRIEF DESCRIPTION This disclosure generally relates to an extension assembly for a vascular access device, as well as related devices, systems, and methods. In some embodiments, a vascular access system may include the extension assembly attached to the vascular access device. In some embodiments, the vascular access device may include a catheter, needle, or other device suitable for blood collection. In some embodiments, during blood collection, the extension assembly can facilitate the adjustment of flow resistance within the vascular access system based on the pressure state within the vascular access system. More specifically, in some embodiments, as the pressure differential between a patient's vein and a blood collection container connected to the vascular access system changes during blood collection, the extension assembly can respond and facilitate the adjustment of flow resistance within the vascular access system. In some embodiments, the extension assembly can decrease the risk of hemolysis. In some embodiments, the extension assembly can simultaneously decrease the risk of hemolysis and decrease the blood collection time during a blood collection procedure.In some implementations, the extension set may also reduce the risk of vein and / or vascular access device collapse. In some embodiments, in response to a high pressure differential, e.g., when the blood collection container is first attached to the vascular access system, the extension assembly can provide greater resistance to flow within the vascular access system to distribute the pressure differential and reduce the shear stress on the red blood cells. In some embodiments, as the blood collection container MA / a / 2U22 / UU 1240 blood fills with blood, can decrease the vacuum within a fluid pathway of the vascular access system, and can decrease the pressure differential. Thus, in some embodiments, to shorten blood collection time, the extension assembly can facilitate the decrease of flow resistance within the vascular access system while maintaining the shear stress of the blood cells below a threshold level. In some embodiments, the extension assembly may be configured for coupling to a catheter assembly and may be referred to as a catheter extension assembly. In some embodiments, the extension assembly may include a distal end, which may include a Luer adapter configured for coupling to a catheter adapter or other suitable vascular access device. In some embodiments, the extension assembly may include a proximal end, which may include a blood collection device. In some embodiments, the blood collection device may include or correspond to a blood collection container. In some embodiments, the blood collection container may include a syringe, a vacuum blood collection tube, a small specimen collection device, or any other container configured to draw blood from a patient due to a pressure differential.In some embodiments, the blood collection device may include a needle assembly, which may include a needle configured to receive the blood collection container. In these and other embodiments, the blood collection container may include the vacuum blood collection tube. In some embodiments, the extension assembly may include an extension tube, which can extend between the distal end of the extension assembly and the proximal end of the extension assembly. In some embodiments, the extension assembly may include a clamp, which can be positioned over the extension tube. In some embodiments, the clamp can be configured to move between a tightened position and a loose position. In some embodiments, the clamp can prevent or reduce fluid flow through the extension tube when it is in the tightened position. In some embodiments, the Luer adapter may be a first Luer adapter. In some embodiments, the blood collection device may include a second Luer adapter. In some embodiments, the extension assembly may include a third Luer adapter, which can be coupled to the second Luer adapter. In some embodiments, the extension tube may include a distal end and a proximal end. In some embodiments, the distal end of the extension tube may be integrated with the first Luer adapter. In some embodiments, the proximal end of the extension tube may be integrated with the third Luer adapter. In other embodiments, the proximal end of the extension tube may be integrated with the blood collection device. MA / a / ¿U¿¿ / UU l ¿40 blood. In some embodiments, the extension tubing may include an absorbent material or an indicator tube. In some embodiments, an internal surface of the extension tubing may include an absorbent material or an indicator tube. In some embodiments, the absorbent material and / or the indicator tube may include one or more markers. In some embodiments, the configuration may cause the blood contained in the extension tubing to flow near the absorbent material or through the indicator tube. In some embodiments, when the blood reaches or saturates a particular marker, a clinician may change the flow resistance within the vascular access system through the extension tubing.In some embodiments, to decrease flow resistance within the vascular access system, the physician may remove the extension assembly from the vascular access system, move the clamp to the untightened position, or perform another action to decrease flow resistance as may be described in more detail in this disclosure. In some embodiments, the extension assembly may include one or more extension tubes. In some embodiments, the extension tube may be a first extension tube. In some embodiments, the extension assembly may include a second extension tube. In some embodiments, the flow resistance of the first extension tube may be greater than the flow resistance of the second extension tube. For example, the first extension tube may be longer than the second extension tube. Additionally or alternatively, in some embodiments, the inside diameter of the first extension tube may be smaller than the inside diameter of the second extension tube. In some embodiments, the flow resistance of the first extension tube may be equal to the flow resistance of the second extension tube.In some embodiments, the second extension tube may include any combination of length and inside diameter such that the flow resistance of the second extension tube is equal to or less than the flow resistance of the first extension tube. In some embodiments, the first and second extension tubes may extend between the distal and proximal ends of the extension assembly. In some embodiments, the clamp may be positioned over the second extension tube. In some embodiments, the second extension tube may extend through the clamp. In some embodiments, the second extension tube may include the absorbent material or the indicator tube. In some embodiments, the configuration may cause the blood contained in the second extension tube to flow near the absorbent material or through the indicator tube. In some embodiments, the first extension tube can be arranged inside the second ML / a / ZUZZ / UU l Z40 extension tube. In some embodiments, when the clamp is in the clamping position, blood may flow through the first extension tube, and blood flow between an outer surface of the first extension tube and an inner surface of the second extension tube may decrease or stop. In some embodiments, to decrease or stop resistance to flow within the vascular access system once the blood collection container has partially filled and the pressure differential has decreased, the clinician may move the clamp to the unclamped position to increase flow rate since the pressure differential has decreased. In some embodiments, the second extension tube may include a distal end and a proximal end. In some embodiments, the distal end of the first extension tube and the distal end of the second extension tube may be integrated with the first Luer adapter. In some embodiments, the proximal end of the first extension tube and the proximal end of the second extension tube may be integrated with the third Luer adapter. In some embodiments, tightening the second Luer adapter relative to the third Luer adapter opens a first fluid path through the first extension tube and closes a second fluid path through the second extension tube. In some embodiments, loosening the second Luer adapter relative to the third Luer adapter opens the first fluid path through the first extension tube and opens the second fluid path through the second extension tube. In some embodiments, to decrease flow resistance within the vascular access system once the blood collection container is partially filled and the pressure differential has decreased, the clinician may loosen the second Luer adapter relative to the third Luer adapter or move the second Luer adapter from a tightened to a loosened position.As a result, in these and other implementations, a flow rate can be increased. In some embodiments, the extension assembly may include a pressure-sensitive valve within the extension assembly. In some embodiments, the pressure-sensitive valve may be arranged in the second extension tube. In some embodiments, the pressure-sensitive valve may be arranged in a portion of the fluid path of the extension assembly distal to the first and second extension tubes. In some embodiments, the fluid path of the extension assembly may extend through the proximal and distal ends of the extension assembly. In some embodiments, the fluid path of the extension assembly may include the first fluid path of the first extension tube and / or the second fluid path of the second extension tube. In some embodiments, the pressure-sensitive valve may be arranged at a junction of the first fluid path. MA / a / ¿U¿¿ / UU l ¿40 of fluid and the second fluid path. In some embodiments, in response to a predetermined first pressure differential within the extension assembly, the pressure-sensitive valve may open with respect to the first extension tube and close with respect to the second extension tube. In some embodiments, in response to a predetermined second pressure differential within the extension assembly, the pressure-sensitive valve may close with respect to the first extension tube and open with respect to the second extension tube. In some embodiments, the first predetermined pressure differential may be greater than the second predetermined pressure differential. In some embodiments, the first and second predetermined pressure differentials may correspond to the pressure differential between the patient's vein and the blood collection container attached to the vascular access system. In some embodiments, a method of blood collection or blood sampling may involve inserting a catheter from a catheter system into the patient's vasculature. In some embodiments, the catheter system may include a catheter assembly, which may include a catheter adapter and the catheter itself. In some embodiments, the catheter may be secured within the catheter adapter and may extend distally from the adapter. In some embodiments, the blood collection method may include attaching the extension assembly to the catheter adapter. In some embodiments, the blood collection method may include blocking blood flow through the second extension tube. In some embodiments, after inserting the catheter system catheter into the patient's vasculature, attaching the catheter extension assembly to the catheter adapter, and blocking blood flow through the second extension tube, the blood collection method may include attaching a blood collection container to the blood collection device or the third Luer adapter. In some embodiments, when the blood collection container is attached to the blood collection device or the third Luer adapter, the blood collection container may begin to fill with blood.In some embodiments, when the blood collection container has been partially filled with blood, the blood collection method may include opening the second extension tube so as to increase the flow of blood through the second extension tube. In some embodiments, the second extension tube can be extended through the clamp. In these embodiments, blocking blood flow through the second extension tube may involve moving the clamp to the tightened position, and opening the second extension tube may involve moving the clamp to the loosened position. In some embodiments, MA / a / ¿U¿¿ / UU l ¿40 Blocking blood flow through the second extension tube may involve tightening the second luer adapter relative to the third luer adapter. In some embodiments, opening the second extension tube may involve loosening the second luer adapter relative to the third luer adapter. In some embodiments, the extension assembly may include a roller clamp. In some embodiments, the roller clamp may include a movable roller within a track. In some embodiments, the first and second extension tubes may extend through the roller clamp, generally perpendicular to the track. In some embodiments, when blood flow through the second extension tube is blocked, the roller may be positioned close to the second extension tube. In some embodiments, opening the second extension tube may involve moving the roller along the track away from the second extension tube and toward the first extension tube. In some embodiments, the distal end of the extension assembly may include a three-way stopcock, which may have a first port, a second port, and a third port. In some embodiments, the first extension tube may be coupled to the first port, the second extension tube may be coupled to the second port, and the third port may include the first luer adapter configured for coupling with the catheter adapter. In some embodiments, blocking blood flow through the second extension tube may involve turning the three-way stopcock to a first position. In some embodiments, opening the second extension tube may involve turning the three-way stopcock to a second position. 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 so 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 illustrative extension assembly, according to some realizations; Figure 1B is a cross-sectional view of the extension assembly of Figure 1A, ML / a / ZUZZ / UU l Z40 according to some realizations; Figure 1C is a top perspective view of the extension assembly of Figure 1A coupled to an illustrative catheter assembly, according to some embodiments; Figure 2A is a top perspective view of another illustrative extension assembly, according to some realizations; Figure 2B is a cross-sectional view of the extension assembly of Figure 2B, according to some embodiments; Figure 2C is a top perspective view of the extension assembly of Figure 2A coupled to the catheter assembly of Figure 1C, according to some embodiments; Figure 3A is a top perspective view of another illustrative extension assembly, according to some realizations; Figure 3B is a cross-sectional view of the extension assembly of Figure 3A coupled to another illustrative catheter assembly, according to some embodiments; Figure 3C is a top perspective view of the extension assembly of Figure 3A coupled to the catheter assembly of Figure 3B, according to some embodiments; Figure 4A is a top perspective view of another illustrative extension assembly, according to some realizations; Figure 4B is a top perspective view of the extension assembly of Figure 4A coupled to the catheter assembly of Figure 3B, according to some embodiments; Figure 4C is a cross-sectional view of the extension assembly of Figure 4A coupled to the catheter assembly of Figure 3B, according to some embodiments; Figure 5A is a schematic diagram of the extension assembly of Figure 3A, illustrating an illustrative clamp in a tightening position prior to blood entry into the extension assembly, according to some embodiments; Figure 5B is a schematic diagram of the extension assembly of Figure 3A, illustrating blood flowing through an illustrative first extension tube under a high initial pressure differential, according to some embodiments; Figure 5C is a schematic diagram of the extension assembly of Figure 3A, illustrating the clamp being withdrawn or loosened in response to a lower pressure differential, according to some embodiments; Figure 6A is a cross-sectional view of an illustrative second luer adapter and an illustrative third luer adapter, before being coupled together, according to some embodiments; Figure 6B is a cross-sectional view of the second luer adapter and the third MA / a / ¿U¿¿ / UU l ¿40 luer adapter of Figure 6A, which illustrates the second luer adapter tightened with respect to the third luer adapter, according to some embodiments; Figure 6C is a cross-sectional view of the second luer adapter and the third luer adapter of Figure 6A, illustrating the second luer adapter loosened with respect to the third luer adapter, according to some embodiments; Figure 7A is a top perspective view of an illustrative roller clamp that can be used with the extension assembly of Figure 3A or the extension assembly of Figure 4A, according to some embodiments; Figure 7B is a cross-sectional view of the roller clamp of Figure 7A, which illustrates an illustrative roller in a first illustrative position, according to some embodiments; Figure 7C is a cross-sectional view of the roller clamp of Figure 7B, illustrating the roller in a second illustrative position, according to some embodiments; Figure 8 is a cross-sectional view of another illustrative extension assembly coupled to the catheter assembly of Figure 3B, according to some embodiments; Figure 9A is a top perspective view of another illustrative extension assembly coupled to the catheter assembly of Figure 3B, according to some embodiments; Figure 9B is an enlarged top perspective view of a portion of the extension set of Figure 9A, according to some realizations; Figure 9C is a cross-sectional view of the extension assembly of Figure 9A, according to some embodiments; Figure 9D is a cross-sectional view of the extension assembly of Figure 9A, which illustrates another illustrative first extension tube arranged within an illustrative second extension tube and the second extension tube being squeezed, according to some embodiments; Figure 9E is a cross-sectional view of the extension assembly of Figure 9A, illustrating the first extension tube arranged within the second extension tube, according to some embodiments; Figure 10A is a cross-sectional view of a portion of another illustrative first extension tube, which illustrates an illustrative absorbent material prior to the entry of blood into the first extension tube, according to some embodiments; Figure 10B is a cross-sectional view of the portion of the first extension tube from Figure 10A, illustrating the absorbent material in response to blood flow through the first extension tube under a high initial pressure differential, according to some ΜΛ / a / ZUZZ / UU l Z40 realizations; Figure 11A is a cross-sectional view of a portion of another illustrative first extension tube, which illustrates an illustrative indicator tube before blood enters the first extension tube, according to some embodiments; Figure 11B is a cross-sectional view of the portion of the first extension tube in Figure 11A, illustrating the indicator tube in response to blood flow through the first extension tube under the high initial pressure differential, according to some embodiments; Figure 12A is a cross-sectional view of an illustrative junction between another first illustrative extension tube and a second illustrative extension tube, illustrating the junction before the entry of blood into the junction, according to some embodiments; Figure 12B is a cross-sectional view of the junction in Figure 12A, illustrating the junction in response to blood flow through the junction under high initial differential pressure, according to some embodiments; Figure 12C is a cross-sectional view of the junction in Figure 12A, illustrating the junction in response to blood flow through the junction under a lower pressure differential compared to the high initial pressure differential, according to some embodiments; Figure 13 is a partial cross-sectional view of another illustrative extension assembly coupled to the catheter assembly of Figure 3B, according to some embodiments; Figure 14A is a top perspective view of an illustrative catheter system, according to some embodiments; and Figure 14B is a top perspective view of another illustrative catheter system, according to some embodiments. DESCRIPTION OF THE ACHIEVEMENTS With reference to Figures 1A-1C, in some embodiments an extension assembly 10 may include a distal end 12, which may include a Luer adapter 14 configured to attach to a catheter adapter or other suitable vascular access device. In some embodiments, the extension assembly 10 may include a proximal end 16, which may include a blood collection device 18. In some embodiments, the blood collection device 18 may include or correspond to a blood collection container. In some embodiments, the blood collection container may include a syringe, a vacuum blood collection tube, a small sample collection device, or any other container configured to draw blood from a patient due to a pressure differential. In some embodiments, the blood collection device 18 may include a needle assembly 19, which may include a needle 20 configured to receive a collection container of MA / a / 4U44 / UU 1440 blood. In these and other embodiments, the blood collection container may include the vacuum blood collection tube. In some embodiments, the air has been totally or partially removed from the blood collection container so that the pressure inside the blood collection container is lower than the ambient pressure. In some embodiments, the needle assembly 19 may include one or more threads, which may be configured to engage a holder 22, which may generally be cylindrical and may be configured to hold the blood collection container. In some embodiments, the holder 22 may be integrally formed with the needle assembly 19 or may be attached to the needle assembly 19 by joining or other suitable method. In some embodiments, the holder 22 may surround the needle 20. In some embodiments, the needle assembly 19 and the holder 22 may include or correspond to a luer lock access device, such as, for example, the VACUTAINER® LUER-LOK™ ACCESS DEVICE marketed by Becton Dickinson & Company. In some embodiments, the holder 22 may include or correspond to the blood collection tube holder 127 described in U.S. Patent Application No. 62 / 928.69, submitted on October 30, 2019 and entitled BLOOD COLLECTION SYSTEM WITH USER-ADJUSTED PRESSURE MANAGEMENT AND RELATED METHODS, which is incorporated in its entirety by reference. In some embodiments, the Luer adapter 14 may be a first Luer adapter 14. In some embodiments, the extension assembly 10 may include a second Luer adapter 24. In some embodiments, the blood collection device 18 may include the second Luer adapter 24. In some embodiments, the needle 20 may be integrated with the second Luer adapter 24. In some embodiments, an elastomeric sheath 26 may enclose a proximal end of the needle 20. In some embodiments, the elastomeric sheath 26 may include an open distal end 28 and a closed proximal end 30. In some embodiments, when the blood collection container pushes the elastomeric sheath 26 distally, the needle 20 may pierce the elastomeric sheath 26 and be inserted into a cavity of the blood collection container. In some embodiments, the extension assembly 10 may include an extension tube 32, which can extend between the distal end 12 of the extension assembly 10 and the proximal end 16 of the extension assembly 10. In some embodiments, the extension tube 32 may be rigid or semi-rigid, which may reduce the likelihood of kinking. In some embodiments, the extension assembly 10 may include a third Luer adapter 34, which can be coupled to the second Luer adapter 24. In some embodiments, the extension tube 32 may include a distal end 36 and a proximal end 38. In some embodiments, the ML / a / ZUZZ / UU l Z40 distal end 36 can be coupled or integrated with the first luer adapter 14. In some embodiments, the proximal end of the extension tube 32 can be coupled or integrated with the third luer adapter 34. In other embodiments, the proximal end of the extension tube 32 can be coupled or integrated with the blood collection device 18. In some embodiments, the extension assembly 10 may act as a flow resistor in a fluid pathway of a catheter system, illustrated, for example, in Figure 1C, or of another vascular access system. In some embodiments, the catheter system may include a catheter assembly 37, which may include a catheter adapter 39 and a catheter 40. In some embodiments, the catheter 40 may be secured within the catheter adapter 39 and may extend distally from the catheter adapter 39. In some embodiments, the catheter adapter 39 may include a distal end 42, a proximal end 44, and a lumen extending through the distal end 42 and the proximal end 44. In some embodiments, an introducer needle 45 may extend from a needle shield through the catheter 40. In some embodiments, the extension assembly 10 can be attached to the catheter assembly 37 in various suitable ways. In some embodiments, the catheter assembly 37 may be integrated. More specifically, in some embodiments, another extension tube 46 may extend from a side opening 48 of the catheter adapter 39. In some embodiments, a proximal end of the other extension tube 46 may include a fourth Luer adapter 50, which can be attached to the first Luer adapter 14. In some embodiments, the catheter assembly 37 may be straight and / or the first Luer adapter 14 may be attached to the proximal end 44 of the catheter adapter 39.In some embodiments, one or more of the first luer adapter 14, the second luer adapter 24, the third luer adapter 34, and the fourth luer adapter 50 may include a sliding, threaded, or clip-on male luer adapter, a sliding or threaded female luer adapter, a needleless connector, a blunt cannula, or other suitable access device. In some embodiments, catheter assembly 37 may include or correspond to any suitable catheter assembly, 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 catheter assembly. In some embodiments, catheter 40 may include a peripherally inserted central catheter (PICC), a peripherally inserted central catheter (PICC), or a midline catheter. In some embodiments, the fluid pathway of the catheter system may include one or more of the following: catheter 40, catheter adapter 39, other extension tube 46, fourth luer adapter 50, first luer adapter 14, extension tube 32, third luer adapter 34, MA / a / ¿U¿¿ / UU l ¿40 the second adapter Iuer24 and the blood collection device 18. In some embodiments, the extension assembly 10 can reduce the blood flow within the fluid pathway of the catheter system, which in turn can reduce the shear stress for managing hemolysis. In some embodiments, the catheter assembly 37 can be replaced by another type of vascular access device, such as, for example, a venipuncture device, a disposable infusion device, a blood collection access device, or a blood collection container. Blood cells experience shear stress as they flow through a fluid pathway. The maximum shear stress occurs along the wall of the fluid pathway, hence the name wall shear stress. The wall shear stress to which blood cells are subjected is considered a major source of mechanical damage. For a cylindrical fluid pathway, the wall shear stress is typically expressed as: τ = - · ^ · (kr) Lv 7where ΔP is the pressure drop along a path with a length L and an inner radius r, and k is the contraction index. To fill a given volume of the collection tube, V, with a flow rate of Q, the time required can be evaluated simply by: t = - = 8μν · -L / (—) QrπΓ4 7\ L / where μ is the dynamic viscosity of the fluid. Hemolysis is typically associated with both wall shear stress and the time a blood cell is exposed to wall shear stress. From the literature, it has been widely considered that the hemolysis index can be approached as a function of: IH{%) where A, ay β are coefficients. In principle, the hemolysis index is related to the pressure gradient and the characteristic dimension of the cross-section: In some embodiments, the length of the 32 extension tube can be selected based on one or more of the following: the gauge and / or length of a particular catheter, a particular catheter assembly configuration, or a clinical setting. In some embodiments, the 32 extension tube may include a length L from the first 14 luer adapter to the second 24 luer adapter. In some embodiments, the 32 extension tube may include an inner diameter D. iviAazuzz.uu / 40 The fluid flow in an extension tube with a tubular fluid path through it can be analyzed using Poiseuille's equation: πΌ^ΔΡ ΔΡ Q =----= — 128μί Rf where ΔR is a change in the pressure gradient along the extension tube, D and L are the inside diameter and length, respectively, of the tubular fluid path through the extension tube, μ is the viscosity of a fluid, and Rf = is the fluid resistance. The extension tube may include or correspond to the extension tube 32. Since μ is the viscosity of the fluid and is not part of the geometry of the extension tube, a geometric factor Gr is defined such that Rf (the fluid resistance) is Rf = Gf, where Gf = In some embodiments, the extension tube 32 may have multiple sections with lengths (L1, L2, L3) and inner diameters (D1, D2, D3), the geometric factor then being: L1 L2 L3 (jf — TT --A DI4D24D34 In some embodiments, the extension tube 32 may have an inner diameter that changes along the length of the extension tube, the geometric factor then being: _dlGfJo In some embodiments, the extension tube 32 may have a cross-section other than circular. In this case, the geometric factor can be determined by measuring the flow rate (Q) at a given pressure (1ΔP) with a fluid of known viscosity (μ): πΔΡ Gf =----' 128μρ The Gf value can be selected to reduce the maximum shear stress for each catheter size to be equal to or less than the maximum shear stress of a VACUTAINER® ULTRATOUCH™ 21G button blood collection set (marketed by Becton Dickinson & Company), which was previously considered the gold standard for blood collection. In some implementations, Gf can be equal to or greater than 62.42E+06 (cm3) (3.83E+06 (1 / in3)) when using an 18G catheter, which can reduce wall shear stress to minimize hemolysis. In some implementations, Gf can be equal to or greater than 53.30E+06 (cm3) (3.27E+06 (1 / in3)) when using a 20G catheter, which can also reduce wall shear stress to minimize hemolysis. In some embodiments, Gf may be equal to or greater than 54.27E+06 (cm3) (3.33E+06 (1 / in3)) when using a 22G catheter, which may reduce wall shear stress to reduce hemolysis.In some embodiments, Gf may be equal to or greater than 24.45E+07 (cm3) (1.50E+07 (1 / in3)) when using a 24G catheter, which may reduce wall shear stress. ML / a / ZUZZ / UU f to reduce hemolysis. In some embodiments, Gt may include another value. In some embodiments, the Gf value may be selected to reduce the maximum shear stress for each catheter gauge, so that it is equal to or less than the maximum shear stress of a VACUTAINER® ULTRATOUCH™ 25G button blood collection set (marketed by Becton Dickinson & Company). In some embodiments, when using an 18G catheter, Gr may be equal to 62.42E+06 (cm3) (3.83E+06 (1 / in3)) plus or minus 10 percent, plus or minus 25 percent, plus or minus 50 percent, or plus or minus 75 percent, which may reduce wall shear stress to reduce hemolysis. In some embodiments, when using a 20G catheter, Gf may be equal to 53.30E+06 (cm3) (3.27E+06 (1 / in3)) plus or minus 10 percent, plus or minus 25 percent, plus or minus 50 percent, or plus or minus 75 percent, which may reduce wall shear stress to reduce hemolysis. In some embodiments, when using a 22G catheter, Gf may be equal to 54.27E+06 (cm3) (3.33E+06 (1 / in3)) plus or minus 10 percent, plus or minus 25 percent, plus or minus 50 percent, or plus or minus 75 percent, which may reduce wall shear stress to reduce hemolysis.In some embodiments, when using a 24G catheter, Gf may be equal to 24.45E+07 (cm3) (1.50E+07 (1 / in3)) plus or minus 10 percent, plus or minus 25 percent, plus or minus 50 percent, or plus or minus 75 percent, which may reduce wall shear stress to minimize hemolysis. In some embodiments, Gf may include another value, which may be selected based on catheter size. In some embodiments, Gf values ​​may be selected to be the same for catheters from 22G to 18G. In some embodiments, the fluid pathway of the catheter system, which may include one or more of the needle assembly 19, the extension tube 32, and the catheter assembly 37 (which may include the other extension tube 46), may include the entirety of a blood collection pathway through which blood flows during blood collection. The system geometric factor Gfs for the fluid pathway of the catheter system may be determined similarly to that described above. In some embodiments, the system geometric factor Gfs may be equal to or greater than 119.64E+06 (cm3) (7.34E+06 (1 / in3)). In some embodiments, Gfs may include another value. In some embodiments, the geometric factor of the Gfs system may be 119.64E+06 (cm3) (7.34E+06 (1 / in3)) plus or minus 10 percent, plus or minus 25 percent, plus or minus 50 percent, or plus or minus 75 percent.In some implementations, Gfs may include another value, which can be selected based on a catheter gauge. With reference now to Figures 2A-2C, an extension set 52 is illustrated, according to some embodiments. In some embodiments, the extension set 52 may be similar ML / a / ZUZZ / UU f ¿40 or identical to the extension assembly 10 of Figures 1A-1C in terms of one or more included features and / or operation. In some embodiments, the proximal end of the extension tube 32 may be integrated with the blood collection device 18. In some embodiments, the extension assembly 52 may include a clamp 54, which may be disposed on the extension tube 32. In some embodiments, the clamp 54 may be configured to move between a tightened position and a loose position, or between a tighter and a looser position. In some embodiments, the clamp 54 may prevent or reduce fluid flow through the extension tube 32 when the clamp 54 is in the tightened position. In some embodiments, the physician can adjust the flow resistance within the catheter system by manually changing the fluid characteristics of the catheter system using clamp 54. In some embodiments, when clamp 54 is in the tightened position, the flow resistance within the catheter system may be increased, and the blood flow through the extension tube 32 may be reduced. In these embodiments, the risk of hemolysis may be reduced. In some embodiments, to decrease the flow resistance within the catheter system once the blood collection container is nearly full, the physician can move the clamp to the loosened position, which may allow for faster blood collection by reducing the risk of hemolysis. In some embodiments, clamp 54 may include a sliding clamp, which may include a progressively narrowing groove. In these and other embodiments, the extension tube 32 may be flexible and elastic. In some embodiments, the physician may adjust the inside diameter of the extension tube 32 by adjusting the depth of the extension tube 32 within the groove of the sliding clamp. The physician may, in turn, adjust the flow resistance within the extension assembly 52. ​​In some embodiments, clamp 54 may include a roller clamp, a sliding clamp, a clamping clamp, or another suitable type of clamp. With reference now to Figures 3A-3C, an extension assembly 56 is illustrated, according to certain embodiments. In some embodiments, the extension assembly 56 may be similar or identical to the extension assembly 10 of Figures 1A-1C and / or the extension assembly 52 in terms of one or more included features and / or operation. In some embodiments, the extension assembly 56 may include one or more extension tubes. In some embodiments, the extension tube 32 may include or correspond to a first extension tube 58 of the extension assembly 56. In some embodiments, the extension assembly 56 may include a second extension tube 60. MA / a / 2U22 / UU 1240 It is understood that, in some embodiments, the first extension tube 58 may be replaced with any suitable first lumen and / or the second extension tube 60 may be replaced with any suitable second lumen. Thus, in some embodiments, a particular extension assembly may not include the first extension tube 58 and / or the second extension tube 60 and may instead include the first lumen and / or the second lumen. In some embodiments, the first and second lumens may be arranged in a single multi-lumen extension tube or in any other suitable structure. In some embodiments, a distal end of the single multi-lumen extension tube may be coupled or integrated with the first Luer adapter 14. In some embodiments, a proximal end of the single multi-lumen extension tube may be coupled or integrated with the third Luer adapter 34.In some embodiments, a proximal end of the single multi-lumen extension tube can be coupled or integrated with the blood collection device 18. In some embodiments, the flow resistance of the first extension tube 58 may be greater than the flow resistance of the second extension tube 60. For example, the first extension tube 58 may be longer than the second extension tube 60, as illustrated, for example, in Figures 3A–3C. Alternatively, in some embodiments, the inside diameter of the first extension tube 58 may be smaller than the inside diameter of the second extension tube 60, as illustrated, for example, in Figures 4A–4C. In some embodiments, the flow resistance of the first extension tube 58 may be equal to the flow resistance of the second extension tube 60. In some embodiments, the second extension tube 60 may have any combination of length and inside diameter such that the flow resistance of the second extension tube 60 is equal to or less than the flow resistance of the first extension tube 58. In some embodiments, the first extension tube 58 and the second extension tube 60 may extend between a distal end 12 of the extension assembly 56 and a proximal end 16 of the extension assembly 56. In some embodiments, the proximal end 16 of the extension assembly may include the blood collection device 18 or the third Luer connector 34. In some embodiments, a clamp 54 may be provided over the second extension tube 60. In some embodiments, the second extension tube 60 may extend through the clamp 54. In some embodiments, the second extension tube 60 may include a distal end 62 and a proximal end 64. In some embodiments, a distal end 66 of the first extension tube 58 and the distal end 62 of the second extension tube 60 may be integrated with the first luer adapter 14, as illustrated, e.g., in Figure 3B. In some embodiments, a proximal end 68 of the first extension tube 58 and the proximal end 64 of the second extension tube 60 of MA / a / 4U44 / UU 1440 extensions may be integrated with the third luer adapter 34, or there may be one or more components between the proximal ends 64, 68 and the third luer adapter 34, such as, for example, a short tube. In some embodiments, the proximal end 68 of the first extension tube 58 and the proximal end 64 of the second extension tube 60 may be integrated with the blood collection device 18. In some embodiments, when clamp 54 is in the tightened position, flow resistance may increase because blood can flow through the first extension tube 58. In some embodiments, when clamp 54 is in the tightened position, blood flow through the second extension tube 60 may be reduced or eliminated. In some embodiments, to decrease flow resistance once the blood collection container is partially filled and the pressure differential has decreased, the physician may move clamp 54 to the loose position, which may allow for faster blood collection. A blood collection container 69 is illustrated in Figures 3B-3C. With reference now to Figures 4A-4C, an extension assembly 70 is illustrated, according to some embodiments. In some embodiments, the extension assembly 70 may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the extension assembly 10 of Figures 1A-1C, the extension assembly 52 of Figures 2A-2C, and the extension assembly 56 of Figures 3A-3C. In some embodiments, an inside diameter of the first extension tube 58 may be smaller than an inside diameter of the second extension tube 60. In some embodiments, the first extension tube 58 and the second extension tube 60 may have the same length. With reference to Figures 5A-5C, a schematic diagram of an extension assembly having multiple extension tubes is illustrated, according to some embodiments. The extension assembly may correspond to extension assembly 56 or extension assembly 70, for example. In some embodiments, as illustrated in Figure 5A, the clamp 54 may be in the tightening position before blood enters the extension assembly. In some embodiments, as illustrated in Figure 5B, blood may flow through the first extension tube 58 in response to tightening the second extension tube 60. In some embodiments, as illustrated in Figure 5C, when the clamp is removed, the tightening is released, or less tightening is generated, more blood may flow through the second extension tube 60, which may increase the total amount of blood flowing through the extension assembly. With reference now to Figures 6A-6C, a portion of an extension set 72 is illustrated, according to some embodiments. In some embodiments, the extension set 72 may be similar or identical to one or more of the following in terms of one or more MA / a / ¿U¿¿ / UU l ¿40 features included and / or of operation: the 10th extension set of Figures 1A-1C, the 52nd extension set of Figures 2A-2C, the 56th extension set of Figures 3A3C, and the 70th extension set of Figures 4A-4C. In some embodiments, tightening the second Luer adapter 24 relative to the third Luer adapter 34 opens a first fluid path 74 through the first extension tube 58 and closes a second fluid path 76 through the second extension tube 60. In some embodiments, loosening the second Luer adapter 24 relative to the third Luer adapter 34 opens the first fluid path 74 through the first extension tube 58 and closes the second fluid path 76 through the second extension tube 60. In some embodiments, to decrease flow resistance within the extension assembly 72 once the blood collection container is partially filled and the pressure differential has decreased, the physician may loosen the second Luer adapter 24 relative to the third Luer adapter 34 or move the second Luer adapter 24 from a tightened to a loosened position.In some embodiments, the second luer 24 adapter and the third luer 34 adapter may include corresponding threads, and the second luer 24 adapter can be unscrewed relative to the third luer 34 adapter to move the second luer 24 adapter from the tightened position to the loosened position. In some embodiments, the extension assembly 72 may include a third extension tube 78, which may be integrated with the third Luer adapter 34. In some embodiments, the third Luer adapter 34 may include one or more openings 80, each in fluid communication with a particular extension tube. In some embodiments, the opening 80 that is in fluid communication with the first extension tube 58 may remain open depending on whether the second Luer adapter 24 is in the loosened or tightened position with respect to the third Luer adapter 34. In some embodiments, the openings 80 that are in fluid communication with the second extension tube 60 and / or the third extension tube 78 can be blocked by the second Luer adapter 24 when the second Luer adapter 24 is in the tightened position relative to the third Luer adapter 34, as illustrated, for example, in Figure 6B. In some embodiments, the openings 80 that are in fluid communication with the second extension tube 60 and / or the third extension tube 78 can be unlocked in response to the loosened position of the second Luer adapter 24 relative to the third Luer adapter 34, as illustrated, for example, in Figure 6C. In these embodiments, the second Luer adapter 24 can be separated from the openings 80 that are in fluid communication with the second extension tube 60 and / or the third extension tube 78. With reference now to Figures 7A-7C, a portion of a set 82 is illustrated MA / a / ¿U¿¿ / UU l ¿40 extension, according to some embodiments. In some embodiments, the extension assembly 82 may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the extension assembly 10 of Figures 1A-1C, the extension assembly 52 of Figures 2A-2C, the extension assembly 56 of Figures 3A3C, the extension assembly 70 of Figures 4A-4C, and the extension assembly 72 of Figures 6A-6C. In some embodiments, the extension assembly 82 may include a roller clamp 84. In some embodiments, the roller clamp 84 may include a roller 86 movable within a track 88. In some embodiments, the first extension tube 58 and the second extension tube 60 may be extended through the roller clamp 84, generally perpendicular to the track 88. In some embodiments, when blood flow through the second extension tube 60 is blocked, the roller 86 may be positioned near the second extension tube 60, as illustrated, for example, in Figure 7B, to pinch the second extension tube 60. In some embodiments, opening the second extension tube 60 may involve moving the roller 86 along the track 88 away from the second extension tube 60 and toward the first extension tube 58.In some embodiments, when the flow of blood through the first extension tube 58 is blocked, the roller 86 can be arranged in a second position near the first extension tube 58, as illustrated e.g. in Figure 7C, so that it pinches the first extension tube 58. With reference now to Figure 8, an extension set 90 is illustrated, according to some embodiments. In some embodiments, the extension set 90 may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the extension set 10 of Figures 1A-1C, the extension set 52 of Figures 2A-2C, the extension set 56 of Figures 3A-3C, the extension set 70 of Figures 4A-4C, the extension set 72 of Figures 6A-6C, and the extension set 82 of Figures 7A-7C. In some embodiments, the distal end 12 of the extension assembly 90 may include a three-way stopcock 92, which may include a first port 94, a second port 96, and a third port 98. In some embodiments, the first extension tube 58 may be coupled to the first port 94, the second extension tube 60 may be coupled to the second port 96, and the third port 98 may include the first luer adapter 14 configured for coupling with the catheter adapter 39. In some embodiments, blocking blood flow through the second extension tube 60 may involve turning the three-way stopcock 92 to the first position. In some embodiments, opening the second extension tube 60 may involve turning the stopcock 92 MA / a / ¿U¿¿ / UU l ¿40 three-way to a second position. With reference now to Figures 9A-9E, an extension set 100 is illustrated, according to some embodiments. In some embodiments, the extension set 100 may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the extension set 10 of Figures 1A-1C, the extension set 52 of Figures 2A-2C, the extension set 56 of Figures 3A-3C, the extension set 70 of Figures 4A-4C, the extension set 72 of Figures 6A-6C, the extension set 82 of Figures 7A-7C, and the extension set 90 of Figure 8. In some embodiments, the first extension tube 58 may be positioned inside the second extension tube 60. In some embodiments, when the clamp 54 is in the tightened position, blood may flow through the first extension tube 58, and blood flow may be reduced between an outer surface of the first extension tube 58 and an inner surface of the second extension tube 60, as illustrated, for example, in Figure 9D. In some embodiments, to increase resistance to flow within the catheter system once the blood collection container 69 has partially filled and the pressure differential has decreased, the physician may move the clamp 54 to the loosened position so that blood flows between the outer surface of the first extension tube 58 and the inner surface of the second extension tube 60, as illustrated, for example, in Figure 9E.In some embodiments, the first extension tube 58 may be longer than the second extension tube 60 and / or the inside diameter of the first extension tube 58 may be smaller than the inside diameter of the second extension tube 60. In some embodiments, the first extension tube 58 may be configured to collapse at a different pressure differential than the second extension tube 60. In some embodiments, the second extension tube 60 may include a lower durometer than the first extension tube 58. In some embodiments, the second extension tube 60 may be configured to collapse at a lower pressure differential than the first extension tube 58. In some embodiments, at the lower pressure differential, the second extension tube 60 may come into contact with the first extension tube 58 to reduce or stop blood flow between the outer surface of the first extension tube 58 and the inner surface of the second extension tube 60.In some embodiments, when the blood collection container 18 has been partially filled with blood, the blood flow between the outer surface of the first extension tube 58 and the inner surface of the second extension tube 60 may increase. With reference now to Figures 10A-10B, in some embodiments, an internal surface of the first extension tube 58 may include an absorbent material 104. In some embodiments, ML / a / ZUZZ / UU l Z40 configuration can cause the blood contained in the first extension tube 58 to flow close to the absorbent material 104. In some embodiments, when the blood reaches or saturates a particular portion of the absorbent material 104, as illustrated e.g. in Figure 10B, or the entirety of the absorbent material 104, the physician can change the flow resistance by means of a particular extension assembly. In some embodiments, the particular extension set may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the extension set 10 of Figures 1A-1C, the extension set 52 of Figures 2A-2C, the extension set 56 of Figures 3A-3C, the extension set 70 of Figures 4A-4C, the extension set 72 of Figures 6A-6C, the extension set 82 of Figures 7A-7C, and the extension set 90 of Figure 8. In some embodiments, the first fluid pathway 74 through the first extension tube 58 may be narrowed near the absorbent material 104, e.g., through an island 106, which may be disposed within the first fluid pathway 74. In some embodiments, the blood may flow around the island 106 in a distal-to-proximal direction, as illustrated, e.g., in Figure 10B. With reference now to Figures 11A-11B, in some embodiments, the first extension tube 58 may include an indicator tube 108, which may include a first end and a second end connected to a main portion of the first fluid passage 74 of the first extension tube 58. In some embodiments, the configuration may cause the blood contained in the first extension tube 58 to flow through the indicator tube 108, which may include a smaller diameter than the main portion of the first fluid passage 74. In some embodiments, the indicator tube 108 may include one or more markers 110, which may include grooves configured to contain blood or lines. In some embodiments, the markers 110 may provide a visual indicator to the clinician. In some embodiments, when the blood reaches a particular marker 110, as illustrated, for example, in Figure 11B, or all the markers 110, the clinician may change the flow resistance using a specific extension assembly.In some embodiments, the particular extension set may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the extension set 10 of Figures 1A-1C, the extension set 52 of Figures 2A-2C, the extension set 56 of Figures 3A-3C, the extension set 70 of Figures 4A-4C, the extension set 72 of Figures 6A-6C, the extension set 82 of Figures 7A-7C, and the extension set 90 of Figure 8. With reference now to Figures 12A-12C, in some embodiments, the first extension tube 58 and the second extension tube 60 can be joined at a joint 112. In some embodiments, the joint 112 can be arranged inside the first luer adapter 14, close to the MA / a / ¿U¿¿ / UU l ¿40 first luer adapter 14, or in another location within a particular extension assembly. In some embodiments, the particular extension assembly may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the 10 extension assembly of Figures 1A-1C, the 52 extension assembly of Figures 2A-2C, the 56 extension assembly of Figures 3A-3C, the 70 extension assembly of Figures 4A-4C, the 72 extension assembly of Figures 6A-6C, the 82 extension assembly of Figures 7A-7C, and the 90 extension assembly of Figure 8. In some embodiments, the particular extension assembly may include a pressure-sensitive valve 114. In some embodiments, the pressure-sensitive valve 114 may be arranged at a junction of the first fluid passage 74 and the second fluid passage 76. In some embodiments, the pressure-sensitive valve 114 may be arranged in the second extension tube 60. In some embodiments, the pressure-sensitive valve 114 may be arranged in a portion of the fluid passage of the particular extension assembly, distal to the first extension tube 58 and the second extension tube 60. In some embodiments, the fluid passage of the particular extension assembly may extend through the proximal end 16 and the distal end 12. In some embodiments, the fluid passage of the particular extension assembly may include the first fluid passage 74 and / or the second fluid passage 76. In some embodiments, in response to a predetermined first pressure differential within the particular extension assembly, the pressure-sensitive valve 114 may open with respect to the first extension tube 58 and close with respect to the second extension tube 60. In some embodiments, in response to a predetermined second pressure differential within the particular extension assembly, the pressure-sensitive valve 114 may remain open with respect to the first extension tube 58 and open with respect to the second extension tube 60. In some embodiments, the predetermined first pressure differential may be greater than the predetermined second pressure differential.In some embodiments, the first and second preset pressure differentials may correspond to the pressure differential between the patient's vein and the blood collection container attached to the particular extension assembly. In some embodiments, the pressure-sensitive valve 114 may include any suitable type of pressure-sensitive valve. In some embodiments, an internal surface of the particular extension assembly may include one or more grooves adjacent to the pressure-sensitive valve. In some embodiments, the grooves may allow blood to bypass the pressure-sensitive valve 114 and flow into the first extension tube 58, but not into the second extension tube 60. In some embodiments, a method of blood extraction or extraction of a ML / a / ZUZZ / UU Blood sampling may involve inserting a catheter from a catheter system into the patient's vasculature. In some embodiments, the catheter system may include a catheter assembly, which may include a catheter adapter and the catheter. In some embodiments, the catheter may be secured within the catheter adapter and may extend distally from the catheter adapter. With reference to Figure 13, in some embodiments, a pressure-sensitive valve 116 may be arranged within the second extension tube 60, which may be shorter than the first extension tube 58 and / or have a larger inner diameter than the first extension tube 58. In some embodiments, the pressure-sensitive valve 116 may include a duckbill valve, as illustrated, for example, in Figure 13, or another suitable type of pressure-sensitive valve. For example, the pressure-sensitive valve 116 may include a spring-loaded plunger or ball. In some embodiments, the second extension tube 60 may be more flexible than the first extension tube 58 and, therefore, may close at a lower pressure differential than the first extension tube 58. In some embodiments, in response to a predetermined first pressure differential within a particular extension assembly, the pressure-sensitive valve 116 may close and prevent blood from flowing through the second extension tube 60. In some embodiments, in response to a predetermined second pressure differential within the particular extension assembly, the pressure-sensitive valve 116 may open. In some embodiments, the predetermined first pressure differential may be greater than the predetermined second pressure differential.In some embodiments, the particular extension set may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the extension set 10 of Figures 1A-1C, the extension set 52 of Figures 2A-2C, the extension set 56 of Figures 3A-3C, the extension set 70 of Figures 4A-4C, the extension set 72 of Figures 6A-6C, the extension set 82 of Figures 7A-7C, and the extension set 90 of Figure 8. With reference to Figure 14A, a catheter system 118 is illustrated, according to several embodiments. In some embodiments, the catheter system 118 may include an extension assembly 120, which may be integrated with the catheter assembly 37. More specifically, in some embodiments, the distal end 12 of the extension assembly 120 may be integrated with an adapter 122 of the catheter assembly 37, as illustrated, for example, in Figure 14A, or it may be integrated with the catheter adapter 39 itself. In these and other embodiments, the extension assembly 120 cannot be detached from the catheter system 118. In some embodiments, the distal end of the first extension tube 58 or the distal end of the extension tube 32 may be MA / a / ¿U¿¿ / UU l ¿40 integrated with adapter 122 or catheter adapter 39. In some embodiments, adapter 122 may include a Y-adapter, a T-adapter, or another suitable adapter.In some embodiments, the first extension tube 58 and / or the second extension tube 60 (see e.g. Figures 4-9) may be integrated with the side mouth 48. In some embodiments, the other extension tube 46 may be similar or identical to the first extension tube 58 in terms of one or more included features and / or operation. In some embodiments, the 120 extension set may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the 10 extension set of Figures 1A-1C, the 52 extension set of Figures 2A-2C, the 56 extension set of Figures 3A-3C, the 70 extension set of Figures 4A-4C, the 72 extension set of Figures 6A-6C, the 82 extension set of Figures 7A-7C, and the 90 extension set of Figure 8.In some embodiments, the 120 extension set may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the extension sets in Figures 9-13. With reference to Figure 14B, a catheter system 124 is illustrated, according to some embodiments. In some embodiments, the catheter system 124 may include an extension assembly 126, which can be coupled to or integrated with an instrument delivery device 127, which can deliver a probe, catheter, or guidewire through a particular catheter assembly (as illustrated, for example, in Figure 14A). In some embodiments, the first extension tube 58 and / or the second extension tube 60 (see, for example, Figures 4-9) may be integrated into the instrument delivery device 127. In some embodiments, extension assembly 126 may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the extension assembly 10 of Figures 1A-1C, the extension assembly 52 of Figures 2A-2C, the extension assembly 56 of Figures 3A-3C, the extension assembly 70 of Figures 4A-4C, the extension assembly 72 of Figures 6A-6C, the extension assembly 82 of Figures 7A-7C, and the extension assembly 90 of Figure 8. In some embodiments, extension assembly 126 may be similar or identical to one or more of the following in terms of one or more included features and / or operation: the extension assemblies of Figures 9-13. In some embodiments, the instrument delivery device 127 may include any suitable instrument delivery device. In some embodiments, the instrument delivery device 127 may be further described in U.S. Patent Application No. 16 / 037.246, filed July 17, 2018, and entitled EXTENSION HOUSING A PROBE OR INTRAVENOUS CATHETER. 16 / 388,650, filed on April 18, 2019, and entitled INSTRUMENT DELIVERY DEVICE HAVING A ROTARY ELEMENT, in U.S. patent application no. 16 / 037,319, filed on July 17, 2018, and entitled MULTI-DIAMETER CATHETER AND RELATED DEVICES AND METHODS, in U.S. patent application no. 16 / 502,541, filed on July 3, 2019, and entitled DELIVERY DEVICE FOR A VASCULAR ACCESS INSTRUMENT, in U.S. patent application no. 16 / 691,217, filed on November 21, 2019, and entitled SYRINGE-BASED DELIVERY DEVICE FOR A VASCULAR ACCESS INSTRUMENT, in U.S. patent application no. 62 / 794.437, filed on January 18, 2019, and entitled CATHETER DELIVERY DEVICE AND RELATED SYSTEMS AND METHODS, and in U.S. patent application 62 / 830.286, filed on April 5, 2019, and entitled VASCULAR ACCESS INSTRUMENT HAVING A FLUID PERMEABLE STRUCTURE AND RELATED DEVICES AND METHODS, which are incorporated as a reference in their entirety. 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 such 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

CLAIMS 1. A catheter extension assembly, comprising: a distal end, comprising a luer adapter configured for coupling with a catheter adapter; a proximal end, comprising a blood collection device; and an extension tube extending between the distal end and the proximal end.

2. The catheter extension assembly of claim 1, further comprising a clamp disposed on the extension tube, wherein the clamp is configured to move between a tightening position and a non-tightening position.

3. The catheter extension assembly of claim 1, wherein the luer adapter is a first luer adapter, wherein the blood collection device comprises a second luer adapter, further comprising a third luer adapter coupled to the second luer adapter, wherein the extension tube comprises a distal end and a proximal end, wherein the distal end of the extension tube is integrated with the first luer adapter, and wherein the proximal end of the extension tube is integrated with the third luer adapter.

4. The catheter extension assembly of claim 1, wherein the extension tube comprises a distal end and a proximal end, wherein the distal end of the extension tube is integrated with the luer adapter, and wherein the proximal end of the extension tube is integrated with the blood collection device.

5. The catheter extension assembly of claim 1, wherein an inner surface of the extension tube comprises an absorbent material or an indicator tube comprising a plurality of markers, wherein the configuration can cause the blood contained in the extension tube to flow near the absorbent material or through the indicator tube.

6. A catheter extension assembly, comprising: a distal end, comprising a luer adapter configured for coupling with a catheter adapter; a proximal end, comprising a blood collection device; a first extension tube extending between the distal end and the proximal end; and a second extension tube extending between the distal end and the proximal end.

7. The catheter extension assembly of claim 6, further comprising a clamp, wherein the second extension tube extends through the clamp, wherein the clamp is configured to move between a tightening position and a non-tightening position.

8. The catheter extension assembly of claim 7, wherein the first extension tube is longer than the second extension tube.

9. The catheter extension assembly of claim 7, wherein the inside diameter of the first extension tube is smaller than the inside diameter of the second extension tube.

10. The catheter extension assembly of claim 7, wherein an inner surface of the first extension tube comprises an absorbent material or an indicator tube comprising a plurality of markers, wherein the configuration can cause the blood contained in the extension tube to flow near the absorbent material or through the indicator tube.

11. The catheter extension assembly of claim 7, wherein the first extension tube is disposed within the second extension tube, wherein when the clamp is in the tightening position, blood flows through the first extension tube and blood flows between an outer surface of the first extension tube and an inner surface of the second extension tube.

12. The catheter extension assembly of claim 5, wherein the luer adapter is a first luer adapter, wherein the blood collection device comprises a second luer adapter, further comprising a third luer adapter coupled to the second luer adapter, wherein the first extension tube comprises a distal end and a proximal end, wherein the second extension tube comprises a distal end and a proximal end, wherein the distal end of the first extension tube and the distal end of the second extension tube are integrated with the first luer adapter, wherein the proximal end of the first extension tube and the proximal end of the second extension tube are integrated with the third luer adapter, wherein, when the second luer adapter is tightened relative to the third luer adapter,A first fluid path is opened through the first extension tube and a second fluid path is closed through the second extension tube, wherein, when the second luer adapter is loosened relative to the third luer adapter, the first fluid path is opened through the first extension tube and the second fluid path is closed through the second extension tube.

13. The catheter extension assembly of claim 5, further comprising a pressure-sensitive valve within a fluid path of the extension catheter, distal to the first extension tube and the second extension tube, wherein, in response to a first predetermined vacuum pressure level within the catheter extension assembly, the pressure-sensitive valve opens with respect to the first extension tube and closes with respect to the second extension tube, wherein, in response to a second predetermined vacuum pressure level within the catheter extension assembly, the pressure-sensitive valve MA / a / ¿U¿¿ / UU l ¿40 closes with respect to the first extension tube and opens with respect to the second extension tube, wherein the first predetermined vacuum pressure level is greater than the second predetermined vacuum pressure level.

14. The catheter extension assembly of claim 5, wherein the second extension tube comprises a pressure-sensitive valve.

15. A method of blood collection, comprising: inserting a catheter of a catheter system into the vasculature of a patient, wherein the catheter system comprises: a catheter adapter; the catheter extending distally from the catheter adapter; attaching a catheter extension assembly to the catheter adapter, wherein the catheter extension assembly comprises: a distal end, comprising a luer adapter configured for coupling with a catheter adapter; a proximal end, comprising a blood collection device, wherein the blood collection device comprises a needle configured to receive a blood collection container; a first extension tube extending between the distal end and the proximal end; and a second extension tube extending between the distal end and the proximal end; and blocking blood flow through the second extension tube.After inserting the catheter system catheter into the patient's vasculature, attach the catheter extension assembly to the catheter adapter and block blood flow through the second extension tube; attach a blood collection container to the blood collection device, wherein, in response to the coupling of the blood collection container with the blood collection device, the blood collection container begins to fill with blood; when the blood collection container has partially filled with blood, open the second extension tube so as to increase blood flow through the second extension tube.

16. The method of claim 15, wherein the flow resistance of the first extension tube is greater than the flow resistance of the second extension tube.

17. The method of claim 15, wherein the catheter system further comprises a clamp, wherein the second extension tube extends through the clamp, wherein the clamp is configured to move between a tightening position and a non-tightening position, wherein blocking the flow of blood through the second extension tube comprises moving the clamp to the tightening position, and wherein opening the second extension tube comprises moving the clamp to the non-tightening position.

18. The method of claim 15, wherein the catheter system further comprises a roller clamp, wherein the roller clamp comprises a roller movable within a track, wherein the first extension tube and the second extension tube extend through the roller clamp generally perpendicular to the track, wherein, when the flow of blood through the second extension tube is blocked, the roller is disposed in a first position close to the second extension tube, wherein opening the second extension tube comprises moving the roller along the track away from the second extension tube and towards the first extension tube.

19. The method of claim 15, wherein the luer adapter is a first luer adapter, wherein the blood collection device comprises a second luer adapter, further comprising a third luer adapter coupled to the second luer adapter, wherein the first extension tube comprises a distal end and a proximal end, wherein the second extension tube comprises a distal end and a proximal end, wherein the distal end of the first extension tube and the distal end of the second extension tube are integrated with the first luer adapter, wherein the proximal end of the first extension tube and the proximal end of the second extension tube are integrated with the third luer adapter, wherein blocking the flow of blood through the second extension tube comprises squeezing the second luer adapter relative to the third luer adapter,where opening the second extension tube involves loosening the second luer adapter relative to the third luer adapter.

20. The method of claim 15, wherein the distal end of the catheter extension assembly comprises a three-way stopcock having a first port, a second port, and a third port, wherein the first extension tube is coupled to the first port, the second extension tube is coupled to the second port, and the third port comprises the luer adapter configured for coupling with the catheter adapter, wherein blocking blood flow through the second extension tube comprises turning the three-way stopcock to a first position, and opening the second extension tube comprises turning the three-way stopcock to a second position.

21. A catheter extension assembly, comprising: a distal end, comprising a luer adapter configured for coupling with a catheter adapter; a proximal end, comprising another luer adapter configured for coupling with a blood collection device; and an extension tube extending between the distal end and the proximal end, wherein a geometric factor Gf of the extension tube is equal to or greater than a predetermined value to reduce hemolysis.

22. The catheter extension assembly of claim 21, wherein the catheter extension assembly is configured for use with an 18G catheter, wherein the geometric factor Gf of the extension tube is equal to or greater than 62.42E+06 (cm3) (3.83E+06 (1 / in3)). 10 23. The catheter extension assembly of claim 21, wherein the catheter extension assembly is configured for use with a 20G catheter, wherein the geometric factor Gf of the extension tube is equal to or greater than 53.30E+06 (cm3) (3.27E+06 (1 / in3)).

24. The catheter extension assembly of claim 21, wherein the catheter extension assembly is configured for use with a 22G catheter, wherein the geometric factor 15 Gf of the extension tube is equal to or greater than 54.27E+06 (cm3) (3.33E+06 (1 / in3)).

25. The catheter extension assembly of claim 21, wherein the catheter extension assembly is configured for use with a 24G catheter, wherein the geometric factor Gf of the extension tube is equal to or greater than 24.45E+07 (cm3) (1.50E+07 (1 / in3)).

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