Ergonomic syringe

Details Ergonomic syringe Ergonomic syringe

2001-09-21

2003-09-09

Hayes, Michael J (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C222S391000

Reexamination Certificate

active

06616634

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
Not applicable.
BACKGROUND OF THE INVENTION
This invention relates to a manually-operated syringe, having ergonomic advantages, to be used in medical procedures. More particularly, an intent of this ergonomic syringe is its use for injecting radiographically opaque contrast medium into the vascular system of a patient during angiographic procedures, for the purpose of enhancing visualization of the vascular system on angiograms or other radiograms.
The radiographically opaque contrast medium, also called dye, is injected into the vascular system typically through a hollow catheter which has been inserted into a patient's artery or vein. For example, the catheter for coronary angiography is usually inserted into the femoral artery or radial artery. The open end of the catheter through which the dye is introduced into the blood flow is guided through the vascular system to the target area by the operator, normally a physician. The dye is injected through the catheter into the blood vessels being evaluated at the time that the angiogram is recorded. Because the dye is opaque to the x-rays used in angiography, it enhances the contrast on the angiogram so as to better show the interior topography of the blood vessels into which the dye is injected. A minimum density of dye in the blood flow of the vessels being evaluated is required in order for a diagnostically-useful angiogram to result. Dye normally has a higher viscosity than water or blood, with a measured viscosity, in centipoise, of between 2 and 20, where the viscosity of water is 1.
Dye is normally injected from a manually-operated syringe into an attached manifold, and therefrom into an attached catheter, these three items being in fluid communication by direct connection or by hollow tubing. The syringe, manifold, tubing, and proximal end of the catheter are located outside the patient's body. The connections between the syringe, manifold, tubing, and catheter are made using a threaded connector, typically a Luer connector. The manifold is used as a means of connecting the syringe, catheter and sources of dye and sometimes saline solution. By manipulating valves, also commonly known as stopcocks, the operator can open and close channels to the dye, saline and catheter, enabling desired fluid flow.
For coronary angiography, between six and 12 milliliters of dye are normally injected per angiogram; this injection should normally take approximately two seconds. If the injection takes substantially longer than approximately two seconds, the density of the dye in the blood flow decreases, lowering the contrast of the angiogram, thereby reducing its usefulness since the interior topography of the vessels being evaluated will not stand out sufficiently from the background of the angiogram. A catheter used for injecting dye is often also called a diagnostic catheter. Multiple injections of dye are required during each procedure, since many different angiographic views are recorded.
Operators injecting the dye normally use syringes made of plastic or polypropylene, with the barrel of the syringe held with the index and third finger placed either in rings or against flanges formed as part of the barrel, and with the plunger of the syringe actuated by the thumb. In many instances, a ring is formed as part of the end of the plunger, so as to enable forward and backward motion in response to the thumb's direction of movement. This style of syringe has been adequate to administer dye with the sizes of catheters in common use, for example, those sized 6 French or larger. French Size increments are in intervals of 0.3 millimeters; for example, a 6 French catheter has an outside diameter of 2.0 millimeters, and a 7 French catheter has an outside diameter of 2.3 millimeters. Inside diameters vary from catheter to catheter; a 6 French diagnostic catheter can be expected to have an inside diameter of approximately 1.3 millimeters, and a 7 French diagnostic catheter an inside diameter of approximately 1.6 millimeters.
Smaller catheters have been introduced because of benefits associated with the smaller puncture hole required to insert the catheters into the body; as the size of the puncture hole decreases, the risk of puncture site complications and the time required for the patient to ambulate decreases. These recently-introduced smaller diagnostic catheters, in 4 French and 5 French sizes, have narrower lumens; a 4 French catheter can be expected to have an inside diameter of approximately 1.1 millimeters and a 5 French catheter an inside diameter of approximately 1.2 millimeters. The inside diameter of a 4 French catheter can therefore be about 15% smaller than that of a 6 French catheter and about 30% smaller than that of a 7 French catheter.
The smaller inside diameters of the 4 French and 5 French catheters make manual injection of the viscous dye more difficult compared with larger catheters. This difficulty is caused by the increased amount of injection force required to propel the dye through a smaller lumen diameter to approximate the same density of dye in the blood flow as is normally achieved with larger-diameter catheters. The degree of difficulty in maintaining a minimum density of dye in the blood flow has not normally been a problem with catheters sized 6 French or larger. As lumen sizes decrease, operator hand strength becomes a limiting factor in the proper administration of dye, even when two hands are used to inject. Where the operator's hand strength is not sufficient, for example after repeated injections, lower quality angiograms result and the operator's wrist, hand and fingers become fatigued and incur a high risk of disability due to either acute or repetitive motion injury. This in turn reduces the adoption rate of the smaller diagnostic catheters, delaying realization of the benefits of lower complication risk and earlier post-procedure ambulation.
Therefore a means of injecting dye through catheters sized 5 French or smaller is needed, which reduces stress on the operator's hand, wrist and fingers while providing a density of dye in the blood flow of the vessels being evaluated sufficient for diagnostic purposes.
One approach to alleviating this problem includes the same type of manifold and catheter normally used in angiographic procedures, but which substitutes an electro-mechanical injector for the manually-operated syringe. Examples of such injectors are described in U.S. Pat. Nos. 6,221,045, 5,383,858, 4,854,324, 4,677,980 and 4,006,736. These injectors were initially developed for purposes of injecting the larger volume of dye into the ventricles of the heart required for ventriculography, and are operated by inputting instructions and then actuating the device, which then automatically injects the pre-set amount of dye at the pre-set flow rate. Although useful and generally safe for ventriculography, these injectors' use in angiography incurs additional risk because of the smaller tolerances involved with injecting into the much smaller volume of a blood vessel, combined with possible unplanned variation in rate or volume of dye administration. Another important disadvantage of these injectors is that, in the event of unforeseen vessel interior topography, malfunction, or inputting improper settings when injecting into a blood vessel, a rupture or other damage could occur resulting in severe adverse health outcomes including death. An additional disadvantage is the very high cost of the injectors, both for acquiring the equipment, maintaining it during its useful life, and for procuring the disposable supplies required for its operation. A further disadvantage is the injector's large size and complexity of operation.
Manually-operated syringes have not substantially changed since the introduction of the 4-French and 5-French catheters and are similar in general form and construction to that shown

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