WO2015038632A1

WO2015038632A1 - Devices and methods for enteral and parenteral administration of fluids at controlled and constant delivery rates

Info

Publication number: WO2015038632A1
Application number: PCT/US2014/054970
Authority: WO
Inventors: Meredith A. MORGAN; Edward Orton
Original assignee: Morgan Meredith A; Edward Orton
Priority date: 2013-09-14
Filing date: 2014-09-10
Publication date: 2015-03-19

Abstract

The invention provides novel devices and methods for enteral or parenteral delivery (e.g., by the enteral, intravenous and subcutaneous routes of administration) of fluids at a about constant and controlled flow rate to humans and other species.

Description

DEVICES AND METHODS FOR ENTERAL AND PARENTERAL ADMINISTRATION OF FLUIDS AT CONTROLLED AND CONSTANT

DELIVERY RATES

Priority Claims and Related Patent Applications

[0001] This application claims the benefit of priority from U.S. Provisional Application Serial No. 61/877,978, filed on September 14, 2013, the entire content of which is incorporated herein by reference in its entirety.

Technical Fields of the Invention

[0002] The invention generally relates to medical equipment. More particularly, the invention relates to novel devices and methods for parenteral and enteral delivery (e.g., by the enteral, intravenous and subcutaneous routes of administration) of fluids at about constant and controlled flow rates to humans and other species.

Background of the Invention

[0003] Enteral, intravenous (IV) and subcutaneous (SC) administration of fluids (hereafter collectively referred to as "IV" or "infusion" or "IV infusion" though recognized by the medical community as well-differentiated routes of administration) are common practices throughout the world in response to a large variety of medical conditions including, for example, providing nutrition, restoring lost fluids, electrolytes, vitamins and minerals, maintaining fluid balance during surgical conditions, and for administering medications directly into the circulatory system, subcutaneous tissues or gastrointestinal tract. Nonetheless, the practice of IV infusion therapy is accompanied by a high incidence of adverse medical events arising from both human and medical device failures. (Peterfreund, et al. 2013 "Critical parameters in drug delivery by intravenous infusion" Expert Opin. Drug Deliv. 2013 Apr 9; Westbrook, et al. 2011 "Errors in the administration of intravenous medications in hospital and the role of correct procedures and nurse experience" BMJ Qual. Saf. 20: 1027el034; Lee, et al. 2012 "Analysis of infusion pump errorlogs and their significance for healthcare" British J. Nursing vol. 21, No. 8 - Supp. 25, Apr 2012, pp. S12-S20; Scanlon 2012 "The role of smart infusion pumps in patient safety" Pediatr. Clin. North Amer. 59 (6): 1257-1267; Corbett 2007 "Intravenous fluids: its more than just fill er up" Practical Gastroenterology 44-60; Cousins, et al. 2005 "Medication errors in intravenous drug preparation and

administration: a multicentre audit in the UK, Germany and France" BMJ Qual. Saf. Health Care 14:190-195.)

[0004] When larger volumes (i.e., greater than a few mLs) of fluid are administered by IV, this is typically done by a process commonly known as "IV drip". IV drip may be performed by either of two processes: gravity feed or infusion pump. In the context of this discussion the term infusion pump is understood to include, for example, electrically- powered pumps as well as pressurized systems, which devices are well-known to those practiced in the art of medical infusion. As illustrated in FIG. 1, a representative set up for a conventional gravity IV drip procedure includes an infusion (or fluid) reservoir (101) for example a plastic bag or a glass bottle (the "infusion reservoir" or "bag") containing the administration fluid, and an administration set comprising a length of plastic tubing (107) which connects a hollow plastic needle (102) for attachment to the infusion reservoir, a drip rate monitor (103), a flow control valve (105), a pinch clamp (104) to stop the flow and a terminal fitting (106) (e.g., a Luer-type fitting) to connect to the cannula or needle inserted in the patient's vein. Administration sets are manufactured with standardized drip chambers that deliver a fixed number of drops per mL (e.g., 15 drops per mL) to facilitate measurement of infusion rate by counting drops per unit time. When the infusion reservoir is a rigid glass or plastic bottle, there is an additional requirement that a filtered port (not shown in FIG. 1) is opened to allow ingress of air and prevent vacuum buildup while preserving the sterility of the system. Other components (not shown in FIG. 1) that may be present in administration sets include, for example, in-line filters, check valves and "Y site" injection fitting(s). In some designs the hollow plastic needle and drip rate monitor are fused to form a single component. The administration set fluid flow path from the infusion reservoir passes through the hollow plastic needle, the drip rate monitor, the terminal fitting and optionally, the flow control valve (e.g., when a stopcock valve is used). In another mode of design the flow control valve is not in the fluid flow path but rather acts externally by compression on the tubing to restrict the flow. Typically these administration sets comprise pre-assembled components that are sterilized and packaged in single-use sterile packaging.

[0005] Standard gravity IV drip practice in a clinical setting is to suspend the infusion reservoir with connected administration set from a dedicated support (commonly called an "IV pole") such that the infusion reservoir is about three feet higher than the patient's heart. The flow rate is then set to the desired number of drops per minute by observing the drip rate monitor while adjusting the flow control valve. In cases where the infusion reservoir is a glass bottle there is an additional requirement that a filtered port is opened to allow ingress of air and prevent vacuum buildup in the glass reservoir. The drip rate then must be monitored regularly to maintain the desired rate with periodic adjustment of the flow control valve. As the fluid level in the infusion reservoir decreases, the hydrostatic pressure in the drip line decreases proportionately necessitating flow rate adjustment by a skilled medical practitioner (e.g., R , MD) to assure desired delivery of therapeutic agents. Additionally, it is well known to practitioners in the infusion field that the common compression flow control valves may give rise to administration flow rate errors due to gradual deformation of the tubing in response to the mechanical stress exerted by the valve on the malleable plastic tubing.

[0006] An alternative process for IV administration involves the use of an infusion pump to maintain a constant infusion rate. It is noteworthy that infusion pump

programming errors and electrical and mechanical malfunctions occur at a rate that should be alarming to medical practitioners, patients and medical device regulatory authorities.

[0007] Despite the passage of many decades of IV infusion therapy involving many millions of patients globally there continue to be clinical studies clearly demonstrating that deviations in IV delivery rates are responsible for serious adverse events including patient deaths. Adverse medical events have occurred with both gravity feed and infusion pump administration systems.

[0008] There is an ongoing need for improved IV drip devices that deliver infusates at constant and controlled rates without the need for periodic adjustment nor the need for elaborate equipment such as pumping devices with their associated hazards and expenses. Especially desired is a device that enables IV fluid administration at about constant rates even in settings where electrical power is unavailable or unreliable.

Summary of the Invention

[0009] The invention is based, in part, on a unique design and configuration for IV administration of a fluid that delivers about a constant flow to a patient with neither the need for periodic manual re-adjustment of the flow rate nor the use of a pumping system for constant flow delivery. The present invention achieves a constant flow of infusate through introduction of a siphon configuration with a flow control valve that maintains a constant fluid flow rate despite the decreasing volume of infusate in the reservoir.

[0010] In one aspect, the invention generally relates to a delivery system for delivering a fluid at a constant flow rate without the use of additional electrically or pressurized pumping systems The delivery system includes: a siphon tube comprising an inlet for connection to a fluid reservoir at the lowest point of the fluid reservoir, and an outlet at the opposite end of the siphon tube from the inlet for discharging fluid out of the siphon tube; and a flow control valve in fluid communication with the siphon tube at its outlet to allow control and adjustment of fluid flow out of the siphon tube. The siphon tube is configured such that the fluid necessarily rises from the siphon tube inlet to a level above the maximum fluid reservoir fill level then descends a greater distance to the siphon tube outlet. A flow control valve of the stopcock type (i.e., a valve in the fluid flow path) is preferred for optimal flow rate control. Optionally, a flow control valve of the tubing compression type may be employed when sub-optimal flow rate control is acceptable.

[0011] In another aspect, the invention generally relates to a method for administering an infusate to a subject at a constant rate. The method includes: providing an infusion reservoir for holding the liquid or liquid suspension to be administered; and administering the liquid or liquid suspension via a delivery device, which includes: a siphon tube comprising an inlet for connection to an infusion reservoir at the lowest point of the reservoir, and an outlet at the opposite end of the siphon tube from the inlet for discharging fluid out of the siphon tube; and a flow control valve in fluid communication with the siphon tube at its outlet to allow control and adjustment of fluid flow out of the siphon tube. The siphon tube is configured such that the infusate necessarily rises from the siphon tube inlet to a level above the maximum fluid reservoir fill level then descends a greater distance to the siphon tube outlet.

[0012] In certain embodiments, for applications at very high flow rates (e.g. rates greater than about 500 mL per hour) as used for example in trauma medicine, the invention may incorporate an electronic flow or drop rate meter device to rapidly and accurately measure the flow rate.

Brief Description of the Drawings

[0013] FIG. 1 schematically illustrates a prior art gravity IV drip apparatus as commonly used in current medical practice.

[0014] FIG. 2 schematically illustrates a prior art administration set for administration of a fluid.

[0015] FIG. 3 schematically illustrates a prior art administration set for coadministration of two fluids.

[0016] FIG. 4 schematically illustrates a device for IV administration of a fluid according to an preferred embodiment of the invention, wherein the hollow needle and drip rate monitor are fused into a single component on the siphon tube inlet side and the flow control valve is on the siphon tube outlet side below the level of the siphon tube inlet.

Detailed Description of the Invention

[0017] The invention provides novel devices and methods for enteral and parenteral delivery (especially, e.g., by the enteral, IV and SC routes of administration) of fluids at a constant and controlled flow rate without the need for periodic adjustment or additional elaborate equipment such as pumping devices. The invention employs a siphon tube that provides the driving force for providing a constant delivery rate of the infusate. In particular, the invention enables a novel method of delivering intravenous and/or subcutaneous fluid therapies that minimizes certain medication errors commonly seen in conventional gravity feed systems. Furthermore, the invention circumvents the requirement for electrical power and infusion pumps that limit the practicability while introducing further sources of medication errors. The invention thus has significant impacts on both reducing adverse medical events and reducing the financial burden of unnecessary and unsafe infusion pumps. The siphon driven infusion system described is applicable to standard primary and secondary IV administration sets as well as those for, inter alia, enteral administration, anesthesia, blood administration, burette and extension sets.

[0018] To distinctly describe the device and method of the invention, it is beneficial to examine the conventional IV drip apparatus as schematically illustrated in FIGs. 1-3. The prior art device (100) shown in FIG. 1 is commonly used in current medical practice and includes infusion reservoir (101), hollow needle (102), drip rate monitor (103), pinch clamp (104), flow control valve (105), terminal connector (106), tubing (107) and filtered vent port (108). FIG. 2 illustrates an administration set (200) for administration of a fluid and includes: hollow needle (202); drip rate monitor (203); flow control valve (205); terminal connector (206); filtered vent (208); in line filter (214); check valve (215); and Y connectors (216). FIG. 3 illustrates an administration set (300) for co-administration of two fluids and includes: two hollow needles (302); drip rate monitor (303); three flow control valves (305); terminal connector (306); Y connector (316).

[0019] FIG. 4 schematically illustrates a device for IV administration of a fluid according to a preferred embodiment of the invention. The device allows constant flow discharge of a liquid to a patient. The device (400) includes: hollow needle (402), drip rate monitor (403), flow control valve (405), terminal connector (406), tubing (407), siphon tube retainer (409), infusion reservoir hanger (410) and siphon tube retainer hanger (411). As illustrated, the hollow needle (402) and drip rate monitor (403) are fused into a single unit. Optionally the hollow needle (402) and drip rate monitor (403) may be separate components but still located on the siphon tube inlet side. The siphon tube has an inlet side (412) and an outlet side (413). The hollow needle component (402) may include a filtered vent port to accommodate the use of glass infusion reservoirs. Additional components (not explicitly illustrated such as check valves, Y connectors, inline filters) that do not compromise the fluid transfer induced by the siphon tube may optionally be employed.

[0020] [0021] Referring again to FIG. 4, the hollow needle (402), drip rate monitor (403), terminal connector (406), constitute a continuous path for fluid flow through the tubing (407). The outlet tubing leads to the lower portion of the siphon tube retainer (409) where it encounters the flow control valve (405). The infusate ascends on the siphon tube inlet side (412) and descends on the siphon tube outlet side (413) in FIG. 4. The tubing (407) is attached to the siphon tube retainer (409) and ascends about 1 inch to about 12 inches above the height of the level of full fluid reservoir (FIG.l, 101). From the top of the siphon tube it descends to a level about 1 inch to about 40 inches below that of the siphon inlet tube. Thus, the siphon tube retainer (409) serves to direct and support the tubing in the necessary siphon configuration and a hanger (411) can be used to suspend the siphon tube retainer (409) from a IV pole (or other support). The siphon tube retainer (409) can be fabricated from a variety of materials such as plastics, ceramics, composites, wood or metal, and may be formed in a plurality of 2- or 3- dimensional designs that also serve to maintain the necessary orientation of the siphon tube and the infusion reservoir.

[0022] The siphon tube retainer (409) may incorporate a fitting (410) to which the fluid reservoir (FIG. 1, 101) can be attached to ensure the proper and necessary orientation of the fluid reservoir (FIG. 1, 101) with respect to the siphon tube. This also serves to simplify the set-up of the IV infusion and reduce potential for adverse medical events. As an integral part of the administration set, the siphon tube retainer (409) can optionally be sized for different volumes and types of infusion reservoirs. In another embodiment, the siphon tube retainer may be a separate component from the administration set, but this arrangement may introduce adverse medical events arising from set up errors in connecting the administration set to the siphon tube retainer, limiting its acceptability in practice.

[0023] A number of other configurations or ordering of the components in the fluid flow path may optionally be employed, but in all cases the overriding functional requirement is that placement of the siphon tube must be such that the siphon inlet line is from the bottom of the infusion reservoir and the siphon inlet line ascends to a level above the highest fluid level of the infusion reservoir before descending to outlet at a level below that of the siphon tube inlet. [0024] As exemplification, a manufactured administration set configured as in FIG. 4 was observed by manual drop counting to maintain an constant drip rate of 57 drops per minute over the course of emptying a 500 mL 0.9% saline infusion bag, an experimental duration of approximately 2 hours.

[0025] In one aspect, the invention generally relates to a delivery system for delivering a fluid at a constant, controlled flow rate. The delivery system includes: a siphon tube comprising an inlet for connection to an infusion reservoir at the lowest point of the infusion reservoir, and an outlet at the opposite end of the siphon tube from the inlet for discharging fluid out of the siphon tube; and a flow control valve in fluid communication with the siphon tube at its outlet to allow control and adjustment of fluid flow out of the siphon tube. The siphon tube is configured such that the fluid necessarily rises from the siphon tube inlet to a level above the maximum fluid reservoir fill level then descends a greater distance to the siphon tube outlet.

[0026] In certain embodiments, the delivery system further includes a siphon tube retainer for maintaining the configuration of the siphon tube such that the fluid necessarily rises from the siphon tube inlet to a level above the maximum infusion reservoir fill level then descends a greater distance to the siphon tube outlet.

[0027] In certain embodiments, the siphon tube rises about 1 inch to about 12 inches (e.g., about 2 inches to about 12 inches, about 5 inches about 12 inches, about 8 inches to about 12 inches, about 1 inch to about 10 inches, about 1 inch about 8 inches, about 1 inch to about 5 inches,) above the highest fluid reservoir fill level.

[0028] In certain embodiments, before reaching the flow control valve the siphon tube outlet descends to a level about 1 inch to about 40 inches (e.g., about 5 inches to about 40 inches, about 10 inches to about 40 inches, about 20 inches to about 40 inches, about 1 inch to about 30 inches, about 1 inch to about 20 inches, about 1 inch to about 10 inches, about 1 inch to about 5 inches) below that of the siphon inlet tube.

[0029] In certain embodiments, the delivery system further includes a drip rate monitor placed in fluid flow path between the fluid reservoir and the siphon tube inlet.

[0030] In certain embodiments, the delivery system further includes a first needle or catheter for insertion into the fluid reservoir to establish fluid flow from the fluid reservoir to the siphon tube. [0031] In certain embodiments, the delivery system further includes a second needle or catheter or other type of connector for insertion into or connection to a subject in need of administration of the fluid.

[0032] In certain embodiments, the delivery system further includes component for hanging or supporting a fluid reservoir.

[0033] In certain embodiments, the delivery system further includes a fluid reservoir.

[0034] In certain embodiments, the siphon tube and the fluid reservoir are connected using fittings suitable for fluid flow.

[0035] The volume of the fluid reservoir may be any suitable sizes, for example, from about 10 mL to about 5 L (e.g., from about 10 mL to about 2 L, from about 10 mL to about 1 L, from about 10 mL to about 100 mL, from about 50 mL to about 5 L, from about 100 mL to about 5 L, from about 1 L to about 5 L).

[0036] Similarly, the siphon tube may have any suitable interior diameter, for example, ranging from about 0.2 mm to about 20 mm (e.g., from about 0.2 mm to about 15 mm, from about 0.2 mm to about 10 mm, from about 0.2 mm to about 5 mm, from about 0.5 mm to about 20 mm, from about 1 mm to about 20 mm, from about 5 mm to about 20 mm).

[0037] In certain embodiments the delivery systems may be connected in parallel so as to enable simultaneous administration of fluids using two or more fluid reservoirs.

[0038] The fluid reservoir, the siphon tube and the flow control valve each may be made from any suitable materials (e.g., ceramics, composites, plastics, glass, metallic and other polymer materials, or combinations thereof). In certain embodiments, the fluid reservoir, the siphon tube and the flow control valve are fabricated from glass or plastic. In certain embodiments, the fluid reservoir, the siphon tube and the flow control valve are fabricated from one or more metallic materials. In certain embodiments, the fluid reservoir, the siphon tube and the flow control valve are fabricated from polymeric materials (e.g., polyethylene, fluoropolymers).

[0039] In another aspect, the invention generally relates to a method for administering an infusate to a subject at a constant, controlled rate. The method includes: providing an infusion reservoir for holding the liquid or liquid suspension to be administered; and administering the liquid or liquid suspension via a delivery device, which includes: a siphon tube comprising an inlet for connection to an infusion reservoir at the lowest point of the reservoir, and an outlet at the opposite end of the siphon tube from the inlet for discharging fluid out of the siphon tube; and a flow control valve in fluid communication with the siphon tube at its outlet to allow control and adjustment of fluid flow out of the siphon tube. The siphon tube is configured such that the infusate necessarily rises from the siphon tube inlet to a level above the maximum infusion reservoir fill level then descends a greater distance to the flow control valve at the siphon tube outlet.

[0040] The rate of administering the infusate may be any suitable rate according to the application, for example, from about 0.5 μΐ,/βεΰοηά to about 2 mL/second (e.g., from about 0.5 μΐ,/βεΰοηά to about 1 mL/second, from about 0.5 μί/βεΰοηά to about 500 μΐ,/βεΰοηά, from about 0.5 μΐ,/βεΰοηά to about 200 μΐ,/βεΰοηά, from about 0.5 μί/βεΰοηά to about 100 μΙ_, /second, from about 0.5 μΐ,/βεΰοηά to about 50 μΐ,/βεΰοηά, from about 0.5 μΐ,/βεΰοηά to about 10 μί/βεΰοηά, from about 5 μί/βεΰοηά to about 2 mL/second, from about 5 μί/βεΰοηά to about 1 mL/second, from about 5 μί/βεΰοηά to about 500 μΐ,/βεΰοηά, from about 5 μί/βεΰοηά to about 200 μί/βεΰοηά, from about 5 μΐ,/βεΰοηά to about 100 μΐ,/βεΰοηά).

[0041] Another embodiment of the invention is a system for administration of nutrition or medications via the enteral route. When a person is unable to ingest sufficient food or liquids by mouth, a feeding tube may be introduced directly into the stomach or intestines (e.g., through the abdominal skin, a procedure called a percutaneous endoscopic gastrostomy or alternatively through an intranasal feeding tube). The tube allows enteral feeding or administration of medicine to occur bypassing the mouth and esophagus. An exemplary embodiment of the invention for enteral feeding includes an open tube rather than via a cannula or needle as in the case of IV or SC infusion.

[0042] In another embodiment of the invention the delivery system is modified for applications in different animal species. In these cases the dimensional specifications of the device components may be much larger than those described herein for human infusions.

[0043] In this specification and the appended claims, the singular forms "a," "an," and "the" include plural reference, unless the context clearly dictates otherwise. [0001] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, the preferred methods and materials are now described. Methods recited herein may be carried out in any order that is logically possible, in addition to a particular order disclosed.

Incorporation by Reference

[0002] References and citations to other documents, such as patents, patent

applications, patent publications, journals, books, papers, web contents, have been made in this disclosure. All such documents are hereby incorporated herein by reference in their entirety for all purposes. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material explicitly set forth herein is only incorporated to the extent that no conflict arises between that incorporated material and the present disclosure material. In the event of a conflict, the conflict is to be resolved in favor of the present disclosure as the preferred disclosure.

Equivalents

[0003] The representative examples are intended to help illustrate the invention, and are not intended to, nor should they be construed to, limit the scope of the invention. Indeed, various modifications of the invention and many further embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the full contents of this document, including the examples and the references to the scientific and patent literature included herein. The examples contain important additional information, exemplification and guidance that can be adapted to the practice of this invention in its various embodiments and equivalents thereof.

Claims

1. A delivery system for delivering a fluid at a constant, controlled flow rate,

comprising:

a siphon tube comprising an inlet for connection to a fluid reservoir at the lowest point of the fluid reservoir, and an outlet at the opposite end of the siphon tube from the inlet for discharging fluid out of the siphon tube; and

a flow control valve in fluid communication with the siphon tube at its outlet to allow control and adjustment of fluid flow out of the siphon tube, wherein the siphon tube is configured such that the fluid necessarily rises from the siphon tube inlet to a level above the maximum fluid reservoir fill level then descends a greater distance to the siphon tube outlet.

2. The delivery system of Claim 1, further comprising a siphon tube retainer for maintaining the configuration of the siphon tube such that the fluid necessarily rises from the siphon tube inlet to a level above the maximum fluid reservoir fill level then descends a greater distance to the siphon tube outlet.

3. The delivery system of Claim 1, further comprising drip rate monitor placed in fluid flow path between the fluid reservoir and the siphon tube inlet.

4. The delivery system of Claim 1, further comprising a first needle or catheter for insertion into the fluid reservoir to establish fluid flow from the fluid reservoir to the siphon tube.

5. The delivery system of Claim 4, further comprising a connector for insertion in or connection to a subject in need of administration of the fluid.

6. The delivery system of Claim 5, wherein the connector is a second needle or catheter.

7. The delivery system of Claim 1, further comprising a component for hanging or supporting a fluid reservoir.

8. The delivery system of Claim 1, further comprising a fluid reservoir.

9. The delivery system of Claim 1, wherein the siphon tube and the fluid reservoir are connected using fittings suitable for fluid flow.

10. The delivery system of Claim 1, wherein the fluid reservoir has volume from about 10 mL to about 5 L.

11. The delivery system of Claim 1 , wherein the siphon tube has an interior diameter from about 0.2 mm to about 20 mm.

12. The delivery system of Claim 1, wherein the siphon tube and the flow control valve are fabricated from ceramic, composites, glass, metallic and polymer materials, or combinations thereof.

13. The delivery system of Claim 12, wherein the siphon tube and the flow control valve are fabricated from glass.

14. The delivery system of Claim 12, wherein the siphon tube and the flow control valve are fabricated from polymeric materials.

15. The delivery system of Claim 1, further comprising a second siphon tube

comprising an inlet for connection to a second fluid reservoir at the lowest point of the second fluid reservoir, and an outlet at the opposite end of the siphon tube from the inlet for discharging fluid out of the second siphon tube, thereby allowing simultaneous delivery from two fluids.

16. A method for administering an infusate to a subject at a constant rate, comprising:

providing an infusate reservoir for holding the liquid or liquid suspension to be administered; and

administering the liquid or liquid suspension via a delivery device comprising:

a siphon tube comprising an inlet for connection to an infusion reservoir at the lowest point of the reservoir, and an outlet at the opposite end of the siphon tube from the inlet for discharging fluid out of the siphon tube; and a flow control valve in fluid communication with the siphon tube at its outlet to allow control and adjustment of fluid flow out of the siphon tube, wherein the siphon tube is configured such that the infusate necessarily rises from the siphon tube inlet to a level above the maximum infusate reservoir fill level then descends a greater distance to the siphon tube outlet.

17. The method of Claim 16, wherein the flow rate of administering the liquid or liquid suspension is from about 0.5 μΐ,/βεΰοηά to about 2 mL/second.

18. The method of Claim 17, wherein the flow rate of administering the liquid or liquid suspension is from about 5 μί/βεοοηά to about 1 mL/second.

19. The method of Claim 16, wherein the delivery device further comprises a siphon tube retainer for maintaining the configuration of the siphon tube such that the fluid necessarily rises from the siphon tube inlet to a level above the maximum fluid reservoir fill level then descends a greater distance to the siphon tube outlet.

20. The method of Claim 16, wherein the delivery device further comprises drip rate monitor placed in fluid flow path between the fluid reservoir and the siphon tube inlet.

21. The method of Claim 16, wherein the delivery device further comprises a first needle or catheter for insertion into the fluid reservoir to establish fluid flow from the fluid reservoir to the siphon tube.

22. The method of Claim 21, wherein the delivery device further comprises a

connector for insertion into or connection to a subject in need of administration of the fluid.

23. The method of Claim 21 , wherein the connector is a second needle or catheter.

24. The method of Claim 22, wherein the delivery devices may be connected in

parallel to allow delivery of fluids simultaneously from two or more fluid reservoirs.