Patent Application
20070219533
The present invention relates generally to medical devices. More particularly, the present invention relates to a pressure indicating means in a chest drainage unit.
Chest drainage devices and systems and more particularly suction drainage systems and devices for removing gases and/or liquids from medical patients, such as from the pleural cavity, by means of a pressure differential, are well known in the art. For many years, the standard apparatus for performing the evacuation of the pleural cavity was a drainage system known as the “3-bottle set-up” which includes a collection bottle or chamber, a water seal bottle, and a suction control bottle. A catheter runs from the patient's pleural cavity to the collection bottle, and the suction bottle is connected by a tube to a suction source. The three bottles are connected in series by various tubes to apply suction to the pleural cavity to withdraw fluid and air and thereafter discharge the same into the collection bottle. Gases entering the collection bottle bubble through water in the water seal bottle. The water in the water seal also can prevent the back flow of air into the chest cavity. Suction or “negative” pressure is usually provided by a central vacuum supply in a hospital so as to permit withdrawal of fluids such as blood, water and gas from a patient's pleural cavity by establishing a pressure differential between the suction source and the internal pressure in the patient.
The 3-bottle set-up lost favor with the introduction of an underwater seal drainage system first sold under the name “Pleur-evac”® in 1966 by Deknatel Inc. U.S. Pat. Nos. 3,363,626; 3,363,627; 3,559,647; 3,683,913; 3,782,497; 4,258,824; and U.S. Pat. No. Re. 29,877 are directed to various aspects of the Pleur-evac® system, which over the years has provided improvements that eliminated various shortcomings of the 3-bottle set-up. These improvements have included the elimination of variations in the 3-bottle set-up that existed between different manufacturers, hospitals and hospital laboratories. A principal feature of the Pleur-evac® system is the use of a single, unitary, pre-formed, self-contained unit that embodies the 3-bottle techniques. The desired values of suction can be established by the levels of water in a suction control chamber. These levels are filled according to specified values prior to the application of the system to the patient. Alternatively, dry suction elements can be used and a pressure regulator element can be equipped to regulate the suction and therefore pressure conditions inside the various chambers of the chest drainage unit. In particular, variable, adjustable pressure regulators can be coupled to the flow pathways inside the chest drainage unit to control the suction pressure present inside the collection chamber of the device, and hence the pleural cavity of the patient which is directly in communication with said collection chamber. This can be achieved by modulating or regulating the amount of pressure regulation flow that the pressure regulator draws from the ambient air to mix with the suction flow being drawn by the suction source.
However this pressure regulation function is independent of the actual reading of the regulated pressure inside the device. Current methods of indicating patient pressure are inaccurate by design. Most methods indicate only the pressure at the suction source connection or the amount of flow proximate thereto. The pressure at the suction source connection and that at the collection chamber is assumed to be correct. However that is not always the case. Pressure, head, or other gas dynamic losses in a complex set of flow control elements and valves found in chest drainage devices can lead to significant pressure variations throughout the device, such that the pressure at the suction source and pressure at the collection chamber can be very different. For proper operation of a chest drainage device during surgery, it is desirable to monitor the pressure easily and accurately directly as close to the patient as possible. For a chest drainage assembly, this usually means at the first chamber coupled to the patient, namely, the collection chamber.
It is desirable therefore, to provide for a pressure indication means in a chest drainage unit that can accurately and effectively read the pressure indicative of the actual pressure in a patient. It is further desirable to have a pressure indicator means that can be easily installed and read in a modular chest drainage assembly.
The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus is provided that in some embodiments a chest drainage unit that can accurately and effectively read the pressure indicative of the actual pressure in a patient.
In accordance with one embodiment of the present invention, a pressure indicator for a chest drainage unit is provided, including an outer casing having a longitudinal axis and first and second end portions defining first and second openings, respectively. The indicator includes a linear force resistance element disposed inside outer casing and aligned along the longitudinal axis. The linear force resistance element has a base end attached to the second end portion. A bellows element is disposed inside the outer casing around the linear force resistance element. The bellows element defines a base open end attached to the second end portion of the outer casing around the second opening, and also defines a collapsible inner space in fluid communication with the second opening. An indicator cap is disposed inside the outer casing and coupled to a tip portion of the bellows element opposite the base open end. The bellows element and outer casing define a variable interior space therebetween inside the outer casing in communication with the first opening.
In accordance with another aspect of the present invention, a pressure indicator for a chest drainage device is provided, having an outer casing with a longitudinal axis and first and second end portions defining first and second openings, respectively. An indicator element is disposed inside the outer casing configured to translate along the longitudinal axis. A linear force resistance means is disposed inside the outer casing between the second end portion and indicator element. The linear force resistance means includes a base end coupled to the second end portion and sealed around the second opening to define a pressure-holding inner space inside the linear force resistance means in fluid communication with the second opening. The linear force resistance means and outer casing together define a variable interior space therebetween inside the outer casing in communication with the first opening.
In accordance with another embodiment of the present invention, a pressure indicator in a chest drainage assembly is provided. The chest drainage assembly includes a body defining a collection chamber having a patient fluid intake port. A pressure indicator casing includes a longitudinal axis and first and second end portions defining first and second openings, respectively. An indicator element is disposed inside the casing to translate along the longitudinal axis. A linear force resistance means is disposed inside the casing between the second end portion and indicator element. The linear force resistance means includes a base end coupled to the second end portion and sealed around the second opening to define a pressure-holding inner space inside the linear force resistance means in fluid communication with the second opening. A conduit couples the second opening with the collection chamber.
There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention provides a pressure indicator for a chest drainage unit. The indicator includes an outer casing having a longitudinal axis and a first end with an opening exposed to ambient air and a second end with an opening coupled to communicate with the collection chamber inside a chest drainage unit for reading patient pressure. A linear force resistance element in the form of a spring compressed inside a bellows is disposed inside the outer casing and aligned along the longitudinal axis. An indicator cap is disposed inside the outer casing and coupled to a tip portion of the bellows element. The interior of the bellows communicates with the collection chamber pressure such that the spring and bellows expands and contracts inside the casing to indicate the degree of suction pressure in the collection chamber. The indicator can be installed in a space inside the body of the chest drainage unit or can be attached thereto. The indicator can give a true reading of patient pressure inside the collection chamber of the chest drainage device, allowing for more effective and safer use of the device and assembly.
The pressure indicator device of the present invention can be fitted and installed in a chest drainage unit to read patient pressure as fluids are drained by the unit from a patient. A type of such a chest drainage unit is illustrated in
The collection module includes a fluid intake port 28 for receiving fluids from a patient. A catheter, tube, or similar device can be coupled to the fluid intake port 28 in a variety of ways as is well known in the art. An ambient air port 30 is included on the flow control module 16 as part of a positive pressure relief valve element therein. A filling valve 32, such as a grommet or needle-less fill valve with a luer type fitting, is provided on the flow control module 16 for injecting fluids into the module for filling a manometer chamber or water seal chamber that is needed to control the backflow of gases and to indicate pressure, flow, or breathing, as further explained below. A re-infusion port 34 is provided on the collection module 12 for allowing collected body fluids to be returned to a patient by a re-infusion line. A high negativity pressure relief valve 36 is also provided on the flow control module 16 to prevent excessive negative pressures from building in the device. A small room air entry port or opening 39 is also defined on the flow control module 16, for allowing communication with the pressure indicator assembly of the present invention as explained more fully below.
After exiting the collection chamber 40, the suction flow is transmitted though the flow coupling 22 and enters the flow control module 16 through entry port 18. The flow then proceeds downwards according to the orientation of view in
Thus, the ‘suction flow’ can be transmitted along arrow F2 through the manometer in arm 52 into the water seal chamber 54 via flow arrow F3 which enters through a narrow opening 56 at the bottom of arm 52. An air leak indicator and metering element 58 can be included in chamber 54 as is well known in the art. Flow can then continue along pathway F4 through another passage or arm 60, past another opening 62, and into chamber 64. A high negativity pressure relief valve 66 can be disposed on the flow control module 16 to place chamber 64 in fluid communication with ambient air outside the device when the pressure inside said chamber 64 exceeds a pre-determined negative pressure (gauge or absolute, as the case may be). The flow proceeds though another opening 68 into chamber 69 and along arrow F5 past an opening 70 and into the suction port 20 for capture by the suction source. Thus, the ‘suction flow’ or suction pressure can be transmitted through the device 10, from intake port 28 to exit 20.
When the face plate 26 is bonded to the flow control module 16 and collection module 12, at least a first fluid flow passageway is defined from the entry port 18 on the flow control module 16, through sub-compartments 42 and 48, down through the arm 52, through chamber 54 and arm 60, into chamber 64, and up out though opening 70 into suction port 20, as shown generally along flow arrows F2, F3, F4, and F5. A positive pressure relief valve element is also included into the form of a ball 72 inside sub-compartment 74 above an opening 76.
The pressure regulator module 24 is shown to be sealingly coupled or attached to the flow control module 16 as shown in
The indicator assembly 100 further includes a force resistance element 125 disposed inside outer casing 101 and aligned along the longitudinal axis L, the force resistance element 125 having a base end 128 attached to the second end portion 120, on an opposite side of the cap 110 as shown. As used herein, the term “force resistance element” shall mean any device, mechanism, or element which provides a means to resist an applied external force with a responsive counter-force. As used herein, a “linear force resistance element” shall mean any force resistance element whose responsive counter-force is a linear function of a displacement, translation or contraction of a portion of the linear force resistance element. An example of a linear force resistance element can be a spring. However the present invention encompasses and contemplates any type of force resistance element, such as those produced by a variety of mechanical, electrical, hydraulic, pneumatic, magnetic, or other means well known in the art. In the embodiment shown in
A bellows element 130 is disposed inside the outer casing 101 around the force resistance element 125. The bellows element 130 include abase open end 132 attached proximate the second end portion 120 onto the base end 128 of cap 110 around the second opening 108. The bellows element 130 defines a collapsible inner space 135 in fluid communication with the second opening 128. The bellows element 130 includes a tip portion 138 opposite the base open end 132. A indicator cap 140 is disposed inside the outer casing 101 and coupled to the tip portion 138 of the bellows element 130. Due to the undulating surface of bellows element 130 positioned inside the casing 101, and a narrow annular tolerance space between the indicator cap 140 and the case 101 which allows the indicator cap 140 to slide up and down inside said casing, a variable interior space 150 is defined inside the outer casing 101, which is in communication with the first opening 112.
In operation, the indicator assembly is positioned to receive ambient room air through first opening 112, which fills the variable interior space 150. The second opening 108 is coupled to a pressure holding space, such as the collection chamber of a chest drainage unit that is under suction pressure. Thus, the negative suction pressures are communicated through the opening 108 into the collapsible inner space 135 defined by the bellows element 130 and around the spring 125. A lower pressure inside space 135 and a higher pressure inside space 150 creates a pressure differential that will cause the bellows element 130 and corresponding inner space 135 to collapse and contract. This pressure differential acts as an externally applied force against the force resistance element 125, which will resist the contraction of the bellows 130. As bellows 130 contracts in the direction of axis L, the spring element 125 will provide a counterforce in the opposite direction.
Thus the bellows element 130 and force resistance element 125 expand and contract along the longitudinal axis L inside the outer casing 101 in response to a pressure differential between the first opening 112 and second opening 108.
If the force resistance element 125 is a linear element such as a spring, the counter-resistance of the spring will be proportional to the displacement ‘X’ of the indicator cap 140. As such, calibration of the pressure indicator assembly 100 can be carried out by coupling the device to a known pressure or pressure differential and using that as a ‘set point’ to mark the assembly. Such calibration can occur either within or outside of a chest drainage assembly. This provides a significant advantage in that if calibration is done prior to installation of the indicator component in a chest drainage assembly, the indicator can be easily replaced if the calibration shows structural or function problems with the device. The range of pressures can then be derived from the set point based on the resistive properties of the spring 125. The wrap-around sleeve 105 shown in
Thus when the face plate 26 is applied to the assembly 10, it will have either a window, opening, or non-opaque element that will allow a user to view the movement of the indicator cap 140 in the pressure indicator assembly 100. Such a window or viewing element could also include markings to measure the degree of movement of the indicator cap 140, if said markings were not included on the outer casing 101 or silkscreen 105. In addition, a light-absorbing or glowing material could be applied to the elements of the indicator assembly 100, such as the indicator cap 140, or the inside surface 200 (shown in
Overall, the subject invention presents many advantages over the prior art when using a chest drainage device, such when dialing down pressure, where the pressure indicator 100 of the present invention allows real-time measurement of the change in pressure at the patient end, while known chest drainage devices can include a check valve element that can hold the pressure inside the flow pathways of the chest drainage unit, causing the prior art pressure indicators inside the chest drainage assembly to indicate a pressure different from that of the true patient pressure measurable by the present invention. Other advantages include: (i) being able to read the true patient pressure when the source suction pressure is disconnected, (ii) when the patient develops an air leak in the pleural cavity, or (iii) when the pressure and flow conditions are generally outside of the proper parameters.
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents maybe resorted to, falling within the scope of the invention.
