Chemical apparatus and process disinfecting – deodorizing – preser – Blood treating device for transfusible blood – Oxygenator
Reexamination Certificate
1998-10-08
2001-07-31
Sykes, Angela D. (Department: 3762)
Chemical apparatus and process disinfecting, deodorizing, preser
Blood treating device for transfusible blood
Oxygenator
C422S044000, C604S005010, C604S004010, C604S006090, C210S314000, C210S435000
Reexamination Certificate
active
06267926
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for removing entrained gases from a liquid stream. More specifically, the present invention relates to removing entrained oxygen and other gases present as micro-emboli from a blood stream during blood oxygenation and other procedures.
BACKGROUND OF THE INVENTION
The danger of unwanted air emboli persists in many medical procedures. Before fluid can safely be introduced into the body, entrained gases must be removed. Certain procedures such as blood oxygenation present the risk of embolism. However such procedures have become routine in the operating room. Blood oxygenation is required whenever heart or lung surgery is being conducted, or when a blood stream is directed to an extracorporeal treatment circuit. During open heart surgery, for example, the natural cardiovascular function of the heart and lungs is suspended. The blood is then oxygenated artificially to replace the contained carbon dioxide.
Many types of blood oxygenators are known. One type, known as a membrane oxygenator, comprises first and second conduits separated by a gas transfer membrane permeable to oxygen and carbon dioxide. Oxygen bubbles, or emboli, are undesirable in such systems. However, such entrained gases often are present in the oxygenator circuit and adversely impact on apparatus set up time. For example, some commercially available blood oxygenator circuits have priming times of up to one hour. During oxygenator setup, initial oxygenator priming is done with saline priming solution. Air bubbles may be present in the priming circuit. Therefore, one goal during priming is the removal of gas bubbles in the line.
However, the danger of bubble formation in oxygenation circuits is not restricted to priming. For example, bubbles may be formed and enter the oxygenator circuit during an operation due to bad connections in the blood circuit, by suction of blood and debris from the chest cavity, or the improper set up of the oxygenator or pressure drop through the blood circuit.
Devices are known to address these embolism problems. One class of known devices uses density gradients and gravity to separate relatively large emboli. As the gas bubbles, once separated from the fluid flow, agglomerate and rise upward in fluid flow, ball valve or bubble trap devices effectively remove large emboli from the flow. Some known bubble traps use a non-woven material encasing a foam core which disengages bubbles from the blood flow. The bubbles, once separated from the fluid flow, agglomerate and rise to the top of the trap, and are vented. However, these devices do not remove emboli smaller than the mesh openings. In addition, the priming time with these devices is still unduly long, up to about one hour.
SUMMARY OF THE INVENTION
The present invention provides a method for removing entrained gases in liquids. According to one embodiment, an arterial filter is provided having at least one vacuum port with a vacuum attached to the membrane to provide a negative pressure to increase the liberation and removal of entrained gases from a fluid being introduced to a body.
In a further embodiment, a method is provided for removing entrained gases from a liquid wherein a substantially airtight interconnected liquid circuit is provided for circulating liquid therethrough. A membrane is provided having tubular microporous membrane segments or filaments. The membrane is oriented in a housing having an inlet, an outlet and at least one vacuum port, with the membrane filaments providing a flow through channel for the liquid, extending from the inlet to the outlet. A vacuum is adapted to the vacuum port to provide a negative pressure to the circuit. The entrained gases, usually in the form of undissolved gas bubbles, are withdrawn from the fluid across the filament membranes in the direction of the vacuum and out of the circuit.
A still further embodiment of the present invention provides an apparatus for removing entrained gases from a fluid, the apparatus having a hydrophobic membrane in communication with a negative pressure environment provided by a vacuum.
A further embodiment provides an arterial filter for removing entrained gases from a liquid. The device has a housing with an inlet and an outlet. A tubular hollow membrane array extends substantially from the inlet to the outlet and is adapted to receive and direct a blood flow through the housing. A vacuum port communicates through the housing. A vacuum is attached to the vacuum port, and is operably engaged to apply a regulateable negative pressure to the gas side of the device.
In one embodiment, the housing comprises an upper, central and lower housing each having a housing wall. The upper housing has an inlet through the housing wall. The central housing is connected to the upper housing with a vacuum port extending through the central housing wall. A tubular hollow microporous membrane array is oriented longitudinally through the central housing in fluid communication with the inlet. The array is preferably arranged into a bundle. The lower housing is in communication with the central housing and comprises an outlet through the lower housing wall. It is understood that the arterial filter of the present invention may be manufactured to have one or more segments or housings.
The present invention further provides a method for oxygenating blood by providing an interconnected liquid circuit having a blood oxygenator in the circuit. The oxygenator has a membrane having first and second sides. A blood flow is directed through the oxygenator along the first side of the oxygenator membrane with a pressurized oxygen flow directed to the second side of the oxygenator membrane to oxygenate the blood flow. The blood flow is then directed from the oxygenator to an enclosed filtering membrane array comprising a housing, a blood flow inlet, blood flow outlet, and a vacuum port extending through the housing wall. The membrane is preferably a hydrophilic microporous membrane array. The blood flow proceeds through the membrane array. A vacuum is connected to the vacuum port of the filter and negative pressure is applied to the array to remove entrained gases from the blood flow. An optional oxygen flow is provided to the blood flow across the microporous membrane via an oxygen port to minimize or eliminate loss of dissolved oxygen in the blood.
In a further embodiment, the present invention provides a method for reducing blood oxygenation priming times by operating an in-line arterial filter under negative pressure in the priming circuit to more quickly remove air bubbles from the system and provide a blood oxygenation system with a reduced risk of gas embolism.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.
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Polystanas: The SAFE II Oxygenating System is manufactured by: Polystan AS.8 Walgerholm DK-3500 Vaerlose Denmark “Hollow Fibre Oxygenator With Filtered Hardshell Reservoir”; Sales Brochure.
COBE Laboratories, Inc. 1993 “COBE Optima™ Hollow Fiber Membrane Oxygenator”; Sales Brochure, 1993.
Sorin Biomedical, Inc.; LC45-5000 (Rev. 2/94) “With the Monolyth, Superior Performa
Reed Bradley W.
Weinstein Martin J.
Bianco Patricia M
Celgard Inc.
Hammer III Robert H.
Sykes Angela D.
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