DUAL CHAMBER SYRINGE SET.

Abstract

This document describes a syringe having two variable volumes. The syringe includes a first stopper and a second stopper, with the first stopper connected to a plunger. A first variable volume is located between the first and second stoppers, and a second variable volume is located between the second stopper and a distal end of a syringe barrel. A flow path structure is located at the distal end of the barrel and extends from the distal end of the barrel along the inner side wall of the barrel.

Description

The aspects of this description relate to a dual-chamber syringe assembly for administering two gases or liquids, or for administering and flushing catheters and other vascular access devices (VADs), and methods for flushing a catheter. BACKGROUND Access devices (ADs) are commonly used therapeutic devices and include intravenous (IV) catheters. There are two general classifications of ADs: peripheral catheters and central venous catheters. If not properly maintained, ADs can become obstructed. To ensure that ADs are used correctly and do not become obstructed, practice standards have been developed. These standards include a cleaning procedure, commonly known as a catheter flush or flush. Standards of practice for vascular access (VAD) generally recommend flushing procedures after catheter placement, before fluid infusions, and before and after the administration of medications, blood samples, transfusions, and parenteral nutrition. The purpose of these flushing procedures is to confirm catheter patency, avoid drug incompatibilities, ensure complete drug dose delivery, prevent thrombus formation, and minimize the risk of bloodstream infections. Flushing procedures require different types and volumes of flushing solutions. The most commonly used flushing solutions are saline and / or heparinized solution. The type and volume of flushing solution vary depending on the specific type of catheter. Flushing solution volumes between 5 and 10 mL are most common, but can range from 1 mL to 20 mL. For flushing procedures, an IV line refers to a system containing a VAD, a set of clamped tubing, and may terminate with a port or valve. The most common types of ports are covered by perforatable or pre-cut septa and are known in the field as, and sometimes referred to as, "PRN" ports, from the Latin pro re nata, meaning "when the need arises." Preferably, the septum is made of rubber or another elastomeric material, allowing the insertion of a pointed needle cannula to infuse fluids into or withdraw them from the catheter. Upon withdrawal of the needle cannula, the membrane self-seals. Ports with pre-perforated septa are used with blunt cannulas or the tapered tip of a syringe barrel. The syringe tip or blunt cannula (usually attached to a syringe) is gently pushed through the pre-perforated septum to establish a fluid connection. RC07 Ln / Zznz / E / YIAI Intravenous valves, another type of intravenous access device that does not require a needle with a sharp point, are activated by the tapered tip of a syringe barrel to allow fluid communication between the syringe and the catheter. These valves may contain structures for delivering fluid from a storage compartment within the valve to the catheter and are referred to technically as positive displacement valves. The removal of waste or residue is called "flushing" or "flushing" and prevents the buildup of blood deposits, blood residue, and intravenous medications within a catheter or other VAD device. Such buildup can cause a partial or complete obstruction of the fluid pathway in a catheter system and may also require costly and potentially dangerous methods to flush the affected catheter or a complete catheter replacement. Often, such blockages lead to treatment interruptions that can compromise patient care. The accumulation of residue within a catheter can also increase the risk of infection by providing a culture medium for microorganisms. As an expert in the field will understand, flushing techniques involve injecting a flushing solution, such as saline, into the nasogastric tube (NAT) to remove debris and obstruction. The injection is commonly performed by advancing a plunger rod into the barrel of a pre-filled syringe, thereby expelling the flushing solution into the NAT. When such techniques are used in conjunction with catheters, turbulence is introduced within the catheter, which dislodges any debris or residue adhering to it. Flushing techniques require the application of substantially constant pressure or force to the plunger rod in the distal direction. Gentle or conventional flushing techniques may also involve applying pressure or force that increases or decreases substantially linearly to the plunger rod in the distal direction. After flushing, the clinician can administer a dose of medical fluid, either from a vial that requires extraction or from a separate pre-filled syringe. However, connecting multiple devices to a catheter-associated bloodstream infection (CABSI) introduces the connectors into a non-sterile external environment, presenting the potential for transmitting a catheter-associated bloodstream infection (CABSI), which can be costly and potentially fatal. To decrease the incidence of CABSI and ensure that CABSIs are used and maintained correctly, standards of practice have been developed, including disinfection and cleaning procedures. In clinical practice, administering intravenous medication followed by an intravenous wash typically uses two separate syringes. There is a need for a syringe set that has the means to flush a VAD (vaginal airway). AC07 ίη / ZZΖΠZ / E / YΙΛΙ and administer a dose of medical fluid, thereby reducing the risk of CRBSI. There is also a need for a single syringe for the administration of intravenous medication followed by an intravenous flush to increase physician efficiency and reduce medical waste, which has an environmental benefit. COMPENDIUM A first aspect of the present description relates to a flushing syringe assembly comprising a substantially cylindrical cylinder, a plunger, a first and second stopper, a first and second variable volume, and a flow path structure. The substantially cylindrical cylinder has an open proximal end, a distal end, and an internal side wall. A needleless connector extends from a distal end, and a lumen passes through it. The lumen is in fluid communication with a cavity in the cylinder, which is defined by the open proximal end, the distal end, and the internal side wall. The plunger is disposed within the cylinder with a plunger stem. The distal end includes a connecting feature extending distally from the distal end.The first plug is positioned proximal to the second plug. The first plug comprises a proximal end, a distal end, and an external surface. The proximal end includes an opening configured to receive the connecting feature of the piston rod. The second plug is positioned proximal to the distal end of the cylinder and comprises a proximal end, a distal end, and an external surface. The first variable volume is located between the first and second plugs. The second variable volume is located between the second plug and the distal end of the cylinder. The flow path structure is located at the distal end of the cylinder and extends from the distal end along the inner side wall of the cylinder. In one or more embodiments, the flow path structure is a protrusion extending from the inner side wall of the cylinder and has a semicircular cross-sectional shape. In one or more embodiments, the flow path structure is a protrusion extending from the inner side wall of the cylinder and has a convex cross-sectional shape. In one or more embodiments, the flow path structure is a protrusion extending from the inner side wall of the cylinder and has a concave cross-sectional shape. In one or more embodiments, the flow path structure is a unitary body molded into the inner side wall of the cylinder. In one or more embodiments, the flow path structure is a non-unitary body assembled into the inner side wall of the cylinder. In one or more embodiments, the first plug further comprises a plurality of radial ribs arranged on the external surface of the first plug. RC07 ίη / ΖΖΠΖ / Ε / ΥΙΛΙ In one or more embodiments, the second plug further comprises a plurality of radial ribs arranged on the external surface of the second plug. In one or more modalities, the proximal end of the second plug has an inwardly conical shape configured to receive a distal end of the first plug. In one or more modalities, the distal end of the second plug has an externally conical shape configured to fit and be received by the distal end of the cylinder. In one or more embodiments, the connection feature comprises a plurality of threads for interconnecting with a plurality of female threads integral to the opening of the first plug. In one or more modalities, the needleless connector is an integral part of the distal end of the cylinder. In one or more embodiments, the flow path structure extends at least the length of the second plug and thus creates a flow path between the second plug and the inner side wall of the cylinder when the second plug abuts the distal end of the cylinder. In one or more modalities, when the second plug is completely adjacent to the distal end of the cylinder, the flow path structure creates a flow path from the second variable volume to the cylinder lumen. In one or more of the modalities, the advancement of the second plug against the distal end of the cylinder causes deformation of the second plug because the structure of the flow path interferes with the second plug. In one or more modes, the advancement of the second plug against the distal end of the cylinder creates a flow path between the second plug and the syringe cylinder. In one or more forms, the distal end of the cylinder has a truncated conical shape. In one or more configurations, the flow pathway structure follows the truncated conical shape of the distal end of the cylinder. In one or more configurations, the flow pathway structure extends into the lumen of the cylinder. In one or more modalities, the flow pathway structure has an inclined proximal end, allowing for less restrictive advancement of the second plug against the flow pathway structure. In one or more embodiments, the flow path structure has a first thickness profile TP1 along the inner side wall of the cylinder and a second thickness profile TP2 along the distal end of the cylinder. In one or more embodiments, the first thickness profile TP1 is greater than the second thickness profile TP2. In one or more modes, the syringe is in an initial state, an intermediate state, and a RC07 Ln / Zznz / E / YIAI final state. In one or more modes, the initial state is defined by the plunger being fully retracted in the cavity, the first plug and second plug being separated within the cavity by the first variable volume, and the second plug and distal end of the barrel being separated within the cavity by the second variable volume. In one or more modes, the intermediate state is defined by the plunger being partially advanced in the cavity and the second plug being fully advanced against the distal end of the barrel, and the advancement of the second plug causing the expulsion of the contents of the second variable volume through the lumen, thus essentially eliminating the second variable volume.In one or more modalities, the final state is defined when the plunger is fully advanced into the cavity and the distal end of the first plug collides with the proximal end of the second plug, eliminating the first variable volume. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a cross-sectional view of a second syringe assembly in an initial state. Figure 2 shows a cross-sectional view of the syringe assembly of Figure 1 in an intermediate state. Figures 3A and 3B illustrate perspective views of a first plug of the syringe assembly of Figure 1. Figure 3C illustrates a cross-sectional view of the first plug in Figure 3A. Figures 4A and 4B illustrate perspective views of a second plug of the syringe assembly of Figure 1. Figure 4C illustrates a cross-sectional view of the second plug in Figure 4A. Figures 5A to 5D illustrate cross-sectional views of the syringe assembly of Figure 1 in a final state. Figures 6A and 6B illustrate a cross-sectional view of the syringe assembly of Figure 1 in its final state. DETAILED DESCRIPTION Before describing several illustrative methods of description, it should be understood that description is not limited to the construction details or process stages outlined below. Description can take other forms and be practiced or carried out in various ways. In this description, a convention is followed in which the distal end of the device is the end closest to a patient and the proximal end of the device is the end furthest from the patient and closest to a doctor. With regard to the terms used in this description, the following are provided: RC07 ίη / ΖΖΠΖ / Ε / ΥΙΛΙ following definitions. As used here, the use of "un", "una", "el" and "la" includes both singular and plural. As used here, the term "catheter-related bloodstream infection," or "CRBSI," refers to any infection that results from the presence of a catheter or IV line. As used herein, the term "Luer connector" refers to a connecting collar that is the standard way to join syringes, catheters, hub needles, IV tubing, etc. The Luer connector consists of interlocking male and female tubes, slightly tapered to ensure a secure fit even with a simple push / twist adjustment. Luer connectors may optionally include an additional external threaded edge for added security. Typically, the male end of the Luer connector is associated with a flush syringe and can interface and connect with the female end located on the vascular access device (VAD). Additionally, the Luer connector has a distal end channel that detachably attaches the Luer connector to the hub of a VAD and a proximal end channel that detachably attaches the Luer connector to the barrel of a syringe. As used herein, ISO 80369-7:2016 defines a specification for standard Luer connectors that includes a 6% taper between the distal and proximal ends. A standard male Luer connector increases in size from the open distal end to the proximal end. A standard female Luer connector decreases in size from the open proximal end to the distal end. According to ISO 80369-7:2016, a standard male Luer connector has an outside cross-sectional diameter, measured 0.75 mm from the distal end of the tip, of between 3.970 mm and 4.072 mm. The taper length of the standard male Luer connector is between 7.500 mm and 10.500 mm. The outside cross-sectional diameter, measured 7.500 mm from the distal end of the tip, is between 4.376 mm and 4.476 mm.As used herein, the phrases "standard male Luer connector" and "standard female Luer connector" shall refer to connectors having the dimensions described in ISO 80369-7, which is incorporated herein by this reference in its entirety. As those skilled in the relevant art will readily understand, while descriptive terms such as "tip," "hub," "thread," "protrusion," "insert," "tongue," "slant," "wall," "top," "side," "bottom," and others are used throughout this descriptive memorandum to facilitate understanding, it is not intended to limit any component that may be used in combination or individually to implement various aspects of the modalities described herein. RC07 ίη / ΖΖΠΖ / Ε / ΥΙΛΙ The examples provided herein are intended to aid a comprehensive understanding of the illustrative modalities described. Accordingly, those skilled in the art will recognize that various changes and modifications can be made to the modalities described herein without departing from the scope and spirit of the description. Furthermore, descriptions of known functions and constructions are omitted for the sake of clarity and conciseness. In an exemplary implementation of the embodiments described herein, the barrel of a syringe includes a distal end having a needleless connection. In one or more embodiments, the needleless connection includes at least one thread and other features in each and every combination that enable it to interface with a corresponding thread or a plurality of threads of a corresponding connector. According to additional exemplary implementations of the modalities of this disclosure, the configuration of the structural elements comprising the needleless connector includes a collar protruding from the distal end of the cylinder and comprising at least one thread for connecting to the corresponding thread or a plurality of threads of a corresponding connector. According to further illustrative implementations of the modalities in this disclosure, the collar or needleless connector can generally be folded or elastically deformed to allow for better compliance with the interference fit with the corresponding connectors. According to still other additional example implementations of the modalities of this disclosure, the needleless connector may comprise female threads having a size and thread pattern that will interconnect with a male fitting of ISO594-2 standard type and / or a male thread having a size and thread pattern that will interconnect with a female fitting of ISO594-2 standard type. An example of an ISO594-2 fitting type is a Q-style fitting. In one or more configurations, a female connector can be selected from the group consisting essentially of needleless connectors, catheter Luer connectors, stopcocks, and hemodialysis connectors. In one or more configurations, the needleless connector is selected from a range of connectors, including Q-Syte, MaxPlus, MaxPlus Clear, MaxZero, UltraSite, Caresite, InVision-Plus, Safeline, OneLink, V-Link, ClearLink, NeutraClear, Clave, MicroClave, MicroClave Clear, Neutron, NanoClave, Kendall, Nexus, InVision, Vadsite, Bionector, etc. In one or more of the configurations, the male connector can be an end of the intravenous tubing or a stopcock. RC07 Ln / Zznz / E / YIAI With reference to the drawings, where similar reference numbers designate identical or corresponding parts throughout the various views, the modalities of the present description are described below. A first aspect of this disclosure relates to a syringe 100 having a barrel 110 and a plunger 102. As shown in Figures 1 and 2, the barrel 110 has a cylindrical shape with an open proximal end, a distal end 114, and an internal side wall 112. Extending from the distal end 114 is a needleless connector 116, which is integral with the distal end 114. The needleless connector 116 has a lumen 118 extending through it. The lumen 118 is in fluid communication with a cavity 120 of the barrel 110, and the cavity 120 is defined by the open proximal end, the distal end 114, and the internal side wall 112 of the barrel 110. The distal end 114 is frustoconical in shape. The plunger 102 comprises a plunger rod 103 having a distal end 104 connected to a first plug 140. The distal end 104 of the plunger rod 103 includes a connection feature 106 extending distally from the distal end 104 of the plunger rod 103. The connection feature 106 is configured to connect removably or non-removably to the first plug 140. In one or more embodiments, the connection feature 106 connects to the first plug 140 by means of a threaded connection. In one or more embodiments, the connection feature 106 connects to the first plug 140 by means of an interference fit. In one or more embodiments, the connection feature 106 connects to the first plug 140 by means of a press fit. In one or more modes, the connection feature 106 connects to the first plug 140 by means of a twist-lock fitting.In one or more embodiments, the connection feature 106 is connected to the first plug 140 by means of sonic welding or a medical-grade adhesive. In one or more embodiments, the first plug 140 is integrally formed with the distal end 104 of the plunger stem 103. As shown in Figures 1 and 2, arranged within cavity 120 are at least two plugs, these at least two plugs include a first plug 140 and a second plug 150. The second plug 150 is arranged close to the distal end 114 of cylinder 110, and the first plug 140 is arranged close to the second plug 150. Between the second plug 150 and the distal end 114 is a first variable volume 142, and the first variable volume 142 is within cavity 120. Between the first plug 140 and the second plug 150 is a second variable volume 152, and the second variable volume 152 is within cavity 120. As shown in Figures 3A to 3C, the first plug 140 comprises a proximal end 144, a distal end 146, and an external surface 147 disposed between the end RC07 Ln / Zznz / E / YIAI proximal 144 and distal 146. In one or more embodiments, the proximal end 144 includes an opening 160 to receive the connection feature 106 of the plunger stem 103. In one or more embodiments, the opening 160 includes a plurality of female threads for interconnecting with the connection feature 106 of the plunger stem 103. In one or more embodiments, the proximal end 144 further includes a plurality of radial protrusions. The distal end 146 of the first plug 140 has an externally conical shape. In one or more embodiments, the distal end 146 has a truncated conical shape. In one or more embodiments, the external surface 147 of the first plug 140 includes a plurality of radial ribs 148. As shown in Figures 4A to 4C, the second plug 150 comprises a proximal end 154, a distal end 156, and an external surface 157 disposed between the proximal end 154 and the distal end 156. The proximal end 154 of the second plug 150 has an internally conical shape configured to receive a distal end (not shown) of the first plug 140. The distal end 156 of the second plug 150 has an externally conical shape. The externally conical shape of the distal end 156 of the second plug 150 is configured to fit and be received by the distal end 114 of the cylinder 110. In one or more embodiments, the external surface 157 of the second plug 150 includes a plurality of radial ribs 158. In one or more embodiments, the distal end 156 includes a plurality of axial ribs 159 and the axial ribs 159 are oriented towards the center of the second plug 150.In one or more modalities, the proximal end 154 has a truncated conical shape. In one or more modalities, the distal end 156 has a truncated conical shape. Again with reference to Figure 1, the first plug 140 is connected to a distal end 104 of a plunger rod 103 by means of the connection feature 106 and the plunger advances within the cavity 120 of the cylinder 110. In the preferred embodiment, the connection feature 106 is at least one male thread disposed on the distal end 104 of the plunger rod 103 and the at least one male thread connects to a female thread disposed within the opening 160 of the first plug 140. A second aspect of the present description relates to a flow path structure 170 disposed at the distal end 114 of the cylinder 110. As shown in Figures 5A to 5D, the flow path structure extends from the distal end 114 along the inner side wall 112 of the cylinder 110. As shown in Figures 5C and 5D, the advancement of the second plug 150 against the distal end 114 of the cylinder 110 causes deformation of the second plug 150 because the flow path structure 170 interferes with the second plug 150. The deformation of the second plug 150 allows fluid flow between the flowway structure 170 and the second plug 150. In particular, as best shown in Figure 5C, the RC07 ίη / ZZΖΠZ / E / YΙΛΙ The flow path structure 170 extends at least the length of the second plug 150 and thus creates a flow path between the second plug 150 and the inner side wall 112 of the cylinder 110 when the second plug 150 abuts the distal end 114 of the cylinder 110. As shown in Figures 5A and 5B, the flow path structure 170 follows the truncated conical shape of the distal end 114 of the cylinder 110. In one or more embodiments, the flow path structure 170 extends into the lumen 118 of the cylinder 110. As shown in Figure 5C, when the second plug 150 is completely abutted by the distal end 114 of the cylinder 110, the flow path structure 170 creates a flow path from the second variable volume. 152 to light 118 of cylinder 110.In one or more modalities, the flowway structure 170 has an inclined proximal end 172, allowing less restrictive advancement of the second plug 150 against the flowway structure 170. In one or more modalities, as best shown in Figure 5B, the flowway structure 170 has a first thickness profile TP1 along the inner side wall 112 of the cylinder 110 and a second thickness profile TP2 along the truncated conical shape of the distal end 114 of the cylinder 110. In one or more modalities, the first thickness profile TP1 is greater than the second thickness profile TP2. In one or more embodiments, the flow path structure 170 is a protrusion extending from the inner side wall 112 of the cylinder 110 and has a semicircular or convex cross-sectional shape. In one or more embodiments, the flow path structure 170 is a protrusion extending from the inner side wall 112 of the cylinder 110 and has a concave cross-sectional shape. In one or more embodiments, wherein the flow path structure 170 is a unitary body molded into the inner side wall 112 of the cylinder 110. In one or more embodiments, the flow path structure 170 is a non-unitary body assembled into the inner side wall 112 of the cylinder 110. Figure 1 illustrates the syringe 100 in an initial state, wherein the first plug 140 and the second plug 150 are separated within the cavity 120 by the first variable volume 142 and the second variable volume 152. In the initial state, the plunger is in an additional retractable position. Figure 2 illustrates the syringe 100 in an intermediate state where the plunger 102 has been partially inserted into the cavity 120. In this intermediate state, the second plug 150 has advanced completely against the distal end 114 of the cylinder 110, and this advancement causes the expulsion of the contents of the second variable volume 152 through the lumen 118, thus essentially eliminating the second variable volume 152. Figures 6A and 6B illustrate the syringe 100 in a final state where the plunger 102 has advanced completely into the cavity 120, with the distal end 146 of the second plug 150 abutting the distal end 114 of the cylinder. RC07 ίη / ΖΖΠΖ / Ε / ΥΙΛΙ 110, thus essentially eliminating the second variable volume 152. For illustrative purposes, as shown in Figure 6A, a gap is depicted between the first plug 140 and the second plug 150 in the final state; however, as shown in Figure 6B, the first plug 140 rests completely on the second plug 150 in the final state. As the first plug 140 advances distally within the cavity 120 by means of the advance of the plunger 102, because the fluid is incompressible, an increase in fluid pressure toward the first variable volume 142 causes the second plug 150 to move distally, which in turn causes the fluid or contents of the second variable volume 152 to be expelled from the lumen 118 of the needleless connector 116. After the first plug 140 advances distally to its final position, a further increase in fluid pressure causes the fluid or contents of the first variable volume 142 to be expelled through the flow path created by the flow path structure 170 through the lumen 118 of the needleless connector 116. Laminar flow can be provided in a relatively controlled manner by the steady advance of the plunger 102 into the cylinder 110. In one or more configurations, the first variable volume 142 is filled with a desired amount of saline wash solution. In one or more configurations, the first variable volume 142 is filled with a desired medication. In one or more configurations, the second variable volume 152 is filled with a desired amount of saline wash solution. In one or more configurations, the second variable volume 152 is filled with a desired medication. In one or more configurations, the first variable volume 142 and the second variable volume 152 are filled with the desired amounts of saline wash solution. In one or more configurations, the first variable volume 142 and the second variable volume 152 are filled with the desired amounts of medication. Additionally, the cylinder 110 of the syringe 100 may include measuring indicators to show the amount of wash solution contained within it.The first variable volume 142 and the second variable volume 152 can be pre-filled with washing solution during or after assembly of syringe 100 using sterile filling methods. Exemplary flushing solutions include saline flush and / or heparin flush. These solutions are well-known in the art and readily available. An example of a saline flush is 0.9% sodium chloride USP for injection. An example of a heparin flush is 0.9% sodium chloride with either 100 units USP of sodium heparin per mL or 10 units USP of sodium heparin per mL. The syringe 100 described in this document may also include visual or other indication elements to indicate the position of the first cap 140 and the second cap 150. The reference throughout this descriptive report to "a modality", "certain RC07 ίη / ZZΖΠZ / E / YΙΛΙ modalities,” “one or more modalities,” or “a modality” means that a particular aspect, structure, material, or characteristic described in relation to the modality is included in at least one modality of the description. Therefore, the occurrences of phrases such as “in one or more modalities,” “in certain modalities,” or “in a modality” in various passages throughout this descriptive report do not necessarily refer to the same modality of the present description. Furthermore, the particular characteristics, structures, materials, or features may be combined in any suitable way in one or more modalities. Although the disclosure herein has been described with reference to particular embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of this disclosure. It will be evident to those skilled in the art that various modifications and variations may be made to the method and apparatus of the description herein without departing from the spirit or scope of the description. Therefore, this disclosure is intended to include modifications and variations that are encompassed by the appended claims and their equivalents.

Claims

1. A syringe comprising: a substantially cylindrical cylinder having an open proximal end, a proximal end and an internal side wall, a needleless connector extending from a distal end and a lumen through it, the lumen being in fluid communication with a cavity in the cylinder, the cavity being defined by the open proximal end, the distal end and the internal side wall; a plunger disposed within the cylinder having a plunger stem, a distal end including a connecting feature extending distally from the distal end; a first plug disposed proximal to a second plug, the first plug comprising a proximal end, a distal end and an external surface, the proximal end including an opening configured to receive the connecting feature of the plunger stem;a second plug disposed proximal to the distal end of the cylinder and the second plug comprising a proximal end, a distal end and an external surface; a first variable volume disposed between the first plug and the second plug; a second variable volume that is between the second plug and the distal end of the cylinder; and a flow path structure disposed at the distal end of the cylinder and extending from the distal end of the cylinder along the inner side wall of the cylinder.

2. The syringe of claim 1, wherein the flow path structure is a protrusion extending from the inner side wall of the cylinder and having a semicircular cross-sectional shape.

3. The syringe of claim 1, wherein the flow path structure is a protrusion extending from the inner side wall of the cylinder and having a convex cross-sectional shape.

4. The syringe of claim 1, wherein the flow path structure is a protrusion extending from the inner side wall of the cylinder and having a concave cross-sectional shape.

5. The syringe of claim 1, wherein the flow path structure is a unitary body molded into the inner side wall of the cylinder.

6. The syringe of claim 1, wherein the flow path structure is a non-unitary body assembled on the inner side wall of the cylinder.

7. The syringe of claim 1, wherein the first plug further comprises a plurality of radial ribs arranged on the external surface of the first plug. RC07 ίη / ZZΖΠZ / E / YΙΛΙ 8. The syringe of claim 1, wherein the second plug further comprises a plurality of radial ribs arranged on the outer surface of the second plug.

9. The syringe of claim 1, wherein the proximal end of the second plug has an inwardly conical shape configured to receive a distal end of the first plug.

10. The syringe of claim 1, wherein the distal end of the second plug has an externally conical shape configured to fit and be received by the distal end of the cylinder.

11. The syringe of claim 1, wherein the connection feature comprises a plurality of threads for interconnecting with a plurality of female threads integral to the opening of the first plug.

12. The syringe of claim 1, wherein the needleless connector is an integral part of the distal end of the cylinder.

13. The syringe of claim 1, wherein the second plug has a length, the flow path structure extends at least the length of the second plug, thereby creating a flow path between the second plug and the inner side wall of the cylinder when the second plug abuts the distal end of the cylinder.

14. The syringe of claim 13, wherein when the second plug is completely adjacent to the distal end of the cylinder, the flow path structure creates a flow path from the second variable volume to the lumen of the cylinder.

15. The syringe of claim 1, wherein the advancement of the second plug against the distal end of the cylinder causes deformation of the second plug because the structure of the flow path interferes with the second plug.

16. The syringe of claim 15, wherein the advancement of the second plug against the distal end of the cylinder creates a flow path between the second plug and the cylinder.

17. The syringe of claim 1, wherein the distal end of the cylinder has a truncated conical shape.

18. The syringe of claim 17, wherein the flow path structure follows the truncated conical shape of the distal end of the cylinder.

19. The syringe of claim 18, wherein the flow path structure extends into the lumen of the cylinder.

20. The syringe of claim 1, wherein the flow path structure has an inclined proximal end, allowing for less restrictive advancement of the second plug against the flow path structure.

21. The syringe of claim 1, wherein the flow path structure has a first RC07 ίη / ZZΖΠZΖ / E / YΙΛΙ profile of thickness TP1 along the inner side wall of the cylinder and a second profile of thickness TP2 along the distal end of the cylinder.

22. The syringe of claim 21, wherein the first thickness profile TP1 is greater than the second thickness profile TP2.

23. The syringe of claim 1, which is in an initial state, an intermediate state, and a final state.

24. The syringe of claim 23, wherein the initial state is defined by the plunger being in a fully retracted position in the cavity, and the first plug and the second plug are separated within the cavity by the first variable volume, and the second plug and the distal end of the cylinder are separated within the cavity by the second variable volume.

25. The syringe of claim 23, wherein the intermediate state is defined by the plunger being in a partially advanced position in the cavity and the second plug being fully advanced against the distal end of the cylinder, and the advancement of the second plug causes the expulsion of the contents of the second variable volume through the lumen and thereby essentially eliminates the second variable volume.

26. The syringe of claim 23, wherein the final state is defined when the plunger is fully advanced in the cavity and the distal end of the first plug collides with the proximal end of the second plug, thereby eliminating the first variable volume.

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