Burette safety valve

Details Burette safety valve Burette safety valve

2001-02-05

2003-04-29

Derakshani, Philippe (Department: 3754)

Surgery

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

Treating material introduced into or removed from body...

C604S250000, C251S009000

Reexamination Certificate

active

06554806

ABSTRACT:

BACKGROUND
The present invention relates to an improved valve system for controlling fluid flow through multiple conduits and, in particular, to a safety valve for use in the administration of medical fluids to patients.
Medical procedures often require introducing fluids into a patient using systems such as parenteral administration sets. Many of these administration sets include multiple, independently operated clamps or valves that control the flow of fluids through the administration set and into the patient. Such sets generally include a vent conduit and at least one supply conduit connected to a supply container such as a fluid-filled bag. To dispense the fluid, a medical operator or other user manually employs the clamps as needed to close or open the conduits of the administration set during the fluid administration. These administration sets may also include injection ports to introduce additives such as antibiotics or other medicaments into the administration solution, as required.
In one medical application, an administration set is used to continuously feed a steady and continuing flow of saline, dextrose or other solution from the supply container intravenously to the patient. The amount fed is limited by the amount in the supply container. In other medical procedures, a precise volume less than the total supply container volume must be fed to the patient over a single flow period. For this volumetric use, the administration set may include a burette chamber in the flow path that may be used to more precisely measure a prescribed volume of solution. In this arrangement, the solution flows from the supply container to the burette chamber to be measured and then to the patient. Depending on the means used to cause the fluid to flow downstream to the patient, an intermediate chamber, such as a drip chamber, may be placed in the flow path downstream of the burette chamber so that fluid flow may be monitored and timed.
In the use of administration sets, it is typical to prime the set before use to eliminate any air that may be harmful to the patient. The valves and clamps of the administration set, including any associated with the burette chamber, must be activated appropriately to assist in entering the priming mode of the administration set. In the priming mode, fluid from the supply container is channeled into the calibrated burette chamber. Typically, individual conduit clamps of the burette chamber are separately manipulated so that both vent and supply conduits are open which allows the source fluid to flow into the burette chamber and to vent the displaced air out the vent conduit. Another clamp may then be used to prime the rest of the administration set conduits and to control the fluid flow through the system.
Once primed, the operator may place the administration set having a burette chamber into the intermittent flow mode which delivers only the medical fluid in the burette chamber to the patient by releasing the vent conduit and closing the supply conduit. The precise amount of fluid that has been measured by the operator with the burette chamber is then administered to the patient. Alternately, the operator may place the administration set into a continuous flow mode by opening the supply conduit to the desired flow level and closing the vent conduit so that the flow of fluid from the supply container is continuous.
Burette chambers typically have an upstream supply conduit through which fluid from a supply source flows into the burette chamber. Burette chambers also typically have an upstream vent conduit through which air in the burette chamber may be vented to the outside as the chamber is filled with fluid from the supply source. Both of these upstream conduits may be clamped shut or may be opened as needed for the flow mode desired. As described above, many administration sets having a burette chamber providing for the priming mode, intermittent flow mode, and continuous flow mode require a particular arrangement of conduit clamps to close or open the upstream vent and supply conduits. These arrangements can become troublesome and inconvenient to an operator. It is necessary for the operator to remember which valve or valves must be open and which must be closed for the particular flow mode desired. Failure to correctly set the valves can result in another mode being configured rather than the one desired.
An effective medical burette administration set must be designed for safety and ease of operation. Preferably, the set includes a safety system that would prevent both upstream conduits (supply and vent conduits) from being simultaneously closed, known as a “closed-closed” flow mode. Such a condition could result in a partial vacuum being formed in the administration set and the burette chamber that could potentially slow or interrupt fluid delivery to the patient or in a worse case, pull blood from the patient's catheter subsequent to the set being removed from an infusion pump. Drawing blood from the catheter presents a risk to the patient of possible clotting or damage to the vessel in the region of the catheter tip. A preferred design would also take measures to avoid contamination to the operator, such as smooth design features that do not tear gloves worn by the operator. Additionally, a preferred design would include unambiguous visual indicators used to gage the flow configuration of the system. These indicators minimize the risk of accidental placement of the administration set into an inadvertent operating state. Known administration sets have certain design limitations that have not entirely overcome these concerns.
U.S. Pat. No. 5,853,398 to Lal et al. proposes a flow-adjusting clamp system in a burette administration set to select the described flow modes and avoid the “closed-closed” flow mode. In the Lal system, a dual-slotted cam mounted at the input end of the burette functions as a selective clamp by closing off flow alternately through the two flexible conduits running through each slot of the cam. One conduit is a vent conduit while the other is a conduit from the fluid reservoir. The slots in the cam vary between a narrow opening and a wide opening. The narrow opening is used for closing off or occlusion of the conduit while the wide opening is used for unrestricted flow. The medical operator grasps the edge of the cam to manually pivot the cam to a selected rotational position. As the cam pivots horizontally, the vertical conduits slide laterally along the open unrestrictive portions and the closing portions of the slots. The edges of the narrow portions of the slots close off flow through the conduits. The wider portions of the slots release flow through the conduits. The slots are aligned so that at any cam position, both slots will not be closed simultaneously as long as the conduits remain in the vertical position. While the medical operator pivots the dual slotted cam through a predetermined arc, the edges of the slots restrict and release the vent and supply conduits to select the priming, intermittent and continuous flow modes.
Administrative sets that use a horizontal dual-slotted cam system potentially introduce operational problems to medical personnel. In order to accurately control flow, the conduits must remain vertically fixed while laterally sliding along the slots to maintain the same rotational position. Below the pivoting cam, the conduits are held in a substantially fixed position by their connections to the burette cap. However, above the pivoting cam, the system does not restrict movement of the flexible conduits which potentially allow the conduits to move from the vertical position. If the pivoting cam is not mounted close enough to the burette cap and if the conduits move from a vertical position such as by bending in response to the narrow slots of the slotted cam, the narrow portion of a cam slot may not fully engage the conduit and full occlusion may not occur. The medical operator may have to manually arrange the conduits in the cam slots or hold the conduits steady while the cam is rotated t

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