Patent Application
20050103332
The present application relates generally to airway management devices, and more particularly, to an airway exchange catheter having a soft distal tip.
Airway exchange catheters are generally used for relatively uncomplicated and atraumatic endotracheal tube (ETT) exchange. The necessity to exchange an existing ETT in a patient for a new one may arise from, among other things, the physician's desire to utilize an ETT of a different size, the displacement of the existing ETT, or the malfunctioning of the existing ETT resulting from conditions such as blockage caused by patient mucous.
Proper placement and use of airway exchange catheters in ETT replacement is well known in the art. One particularly well-known method for replacing an ETT while maintaining ventilation of the patient is described in U.S. Pat. No. 5,052,386, incorporated by reference herein. According to this method, the existing ETT is disconnected from a ventilator, and an airway exchange catheter (referred to therein as an obturator tube) is connected to the ventilator by way of a removable connector. The ventilated airway exchange catheter is then inserted into the placed endotracheal tube. The airway exchange catheter is disconnected from the ventilator via the removable connector, and the ETT is removed from about the catheter. The replacement ETT is then inserted over the airway exchange catheter, and the catheter is reconnected to the ventilator utilizing the removable connector. Once the replacement ETT is properly positioned, the airway exchange catheter is removed and disconnected from the ventilator. The ventilator is then connected to the replacement ETT.
Although procedures for placement of an airway exchange catheter when replacing an ETT are well known, those skilled in the art will appreciate that the catheter is inserted into sensitive and crucial areas of the body's respiratory system. Improper positioning of an airway exchange catheter, or positioning of such a catheter in a patient whose respiratory system has been compromised in some manner, may cause serious consequences to the patient. One particular source of concern is the possibility of trauma or irritation to the tracheal carina or bronchial tree during insertion of the blunt distal tip of an airway exchange catheter. Airway exchange catheters generally are formed of a polymeric material having a relatively high durometer, and the hard distal ends can irritate the sensitive carina tissue. Since the catheters are inserted blindly, it is also possible to perforate the lung of a patient if the high durometer catheter is improperly inserted. In addition, improper positioning may result in excessive airway pressure, which may lead to pulmonary barotraumas in the patient.
It is desired to provide an airway exchange catheter for use in ETT replacement that overcomes the problems associated with prior art catheters, and particularly, a catheter that overcomes the problems caused by high durometer catheters.
The above problems are addressed by the soft-tipped airway exchange catheter of the present invention.
The invention comprises a catheter for use in replacing an endotracheal tube in a patient. The catheter comprises a polymeric catheter body sized for insertion into a passageway of the endotracheal tube, for use in ventilating the patient during replacement of the endotracheal tube with a new tube. The catheter body has a proximal portion, a distal portion and a ventilation passageway extending longitudinally therein. The distal portion has a rigidity that is less than the rigidity of the proximal portion.
In one form thereof, the less rigid distal portion comprises a material having a lower durometer than the material of the proximal portion. In another form thereof, the less rigid distal portion has a reduced thickness compared to the thickness of the proximal portion.
Other details of the invention and its preferred embodiments are provided in the following drawings, description and claims.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It should nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
Endotracheal tubes are well-known medical devices for providing ventilation to a patient. Endotracheal tube 30 includes a ventilator connector 32 at its proximal end for connecting tube 30 to a conventional ventilation apparatus (not shown), a ventilation passageway 34 extending therethrough for passage of a ventilating fluid, and an open distal end 35 through which the ventilating fluid passes to ventilate the patient. Open distal end 35 is shown partially broken away to better illustrate distal end 16 of airway exchange catheter 10. Endotracheal tube 30 typically includes an inflatable cuff 36 positioned in the vicinity of the distal end thereof to securely position and seal the distal end of the endotracheal tube in the trachea 45. Cuff 36 is inflated with air supplied through an inflation tube 38 attached to the external surface of endotracheal tube 30. An inflatable balloon 40 and an airtight connector 42 may be provided at the proximal end of the inflation tube for inflating the cuff and for providing a visual indication of the inflation of the cuff.
As shown in
Connectors 14 and 28 are preferably formed of a hard plastic material, such as polycarbonate. Particularly suitable connectors are the RAPI-FIT® connectors, available from Cook Incorporated, of Bloomington, Ind.
Airway exchange catheters can be formed to have virtually any length. Generally, the length of the catheter will be significantly longer than the length of the endotracheal tube to be replaced, to permit easy handling of the catheter during the replacement procedure. Normally such catheters have a length between about 40 and 100 cm, the exact size being dependent in large part upon the size of the patient and the particular endotracheal tube used during the ventilation of the patient. Most conventional endotracheal tubes have an inner diameter between about 3 and 7 mm. Thus, in order to allow smooth passage of the airway exchange catheter through the endotracheal tube, an airway exchange catheter will typically have an outer diameter of no more than about 2.7 to 6.7 mm (8 to 20 French), or in other words, at least about 0.3 mm less than the inner diameter of the endotracheal tube. The inner diameter of the airway exchange catheter will typically be between about 1.5 and 6 mm. These dimensions are common in the industry, and are not intended to represent limitations to the present invention. Additional general details of airway exchange catheters, removable connectors, and the use of such catheters in replacing an endotracheal tube with a new tube are provided in the incorporated-by-reference U.S. Pat. No. 5,052,386, and need not be repeated herein.
In the inventive airway exchange catheter, proximal portion 12 and intermediate portion 15 normally have either the same, or a similar, durometer. The term “durometer” is used here is its conventional sense to refer to the hardness of a material. A higher durometer indicates a harder material, whereas a lower durometer indicates a softer, more flexible material. Distal portion 16 has a lower durometer than the respective durometers of the proximal and intermediate portions. This results in a distal tip portion that is softer and more flexible than the proximal and intermediate portions. The soft tip results in less trauma to the tracheal carina or bronchial tree upon insertion of the device when compared to the use of a catheter having a higher durometer distal tip portion. It also reduces the possibility of perforating the lung during insertion of the airway exchange catheter.
For purposes of the present invention, the distal portion 16 will normally comprise approximately the distal 5-20 cm of airway exchange catheter 10. This distance is not critical, and a low durometer distal portion of greater or lesser dimension can be created as may be desired. The remaining length of the catheter comprises the proximal and intermediate portions. These portions may be broken down into any convenient proportion of the total length of the catheter, the intention being merely to comprise a main catheter body of higher durometer than the soft tip distal portion.
Although separate proximal and intermediate portions have been denoted on the drawings, this need not be the case. Rather, the catheter 10 may comprise only a proximal portion and a distal portion. In this instance, the high durometer proximal portion would preferably comprise the major length of the catheter, and the low durometer distal portion would preferably comprise a lesser length. However, if desired, the relative lengths can be reversed. In such a case, the high durometer proximal portion would comprise the lesser length, and the lower durometer distal portion would comprise the greater length.
In a particularly preferred embodiment, the proximal portion has a durometer between about 60 and 80, preferably between about 68 and 70, on the Shore D scale. The distal portion has a durometer between about 80 and 90, preferably about 85 on the Shore A scale. When an intermediate portion is present, the durometer of the intermediate portion is somewhere between that of the proximal and distal portions, preferably approximately midway between. However, the durometer of the intermediate section may be as high as that of the proximal section if desired.
Soft distal tip portion 16 may be bonded, or adhered, to the distal end of intermediate portion 14 by conventional means, such as thermal bonding or adhesion. Attachment of distal tips to elongated medical devices is well known in the art, and the skilled artisan can readily determine an acceptable attachment mechanism without undue experimentation. For example, the adjoining edges of the respective portions to be joined can be directly bonded to each other. Alternatively, the adjoining edges can be mutually tapered, slotted, or otherwise configured to mate in a manner to enhance the bonding therebetween. Although the airway exchange catheter may simply consist of two sections of different durometer bonded together, the invention is not so limited. Rather, the catheter can comprise more than two sections of different durometer bonded together. In such event, the sections are preferably aligned in order of decreasing durometer from the proximal end to the distal end, or in other words, from a harder proximal portion to a softer distal portion.
Airway exchange catheters are formed of well-known materials suitable for such use, preferably semi-rigid polymers such as polyester-based urethanes. In a preferred embodiment the proximal and intermediate sections are formed of a polyester-based urethane, and the distal section is formed from a softer material such as a polyether-based urethane. In another preferred embodiment, the polymeric catheter body is formed of radiopaque polyethylene. Conventional radiopaque agents can be added to other polymers to enhance the radiopacity of part, or all, of the catheter.
A particularly preferred way of forming the airway exchange catheter is by a continuous extrusion process. Continuous extrusion processes are known in the art and enable the continuous extrusion, without bonding, of a catheter having portions of different durometer. With continuous extrusion, a catheter can be extruded to be, e.g., rigid or semi-rigid at one end and soft at the other end. The catheter can be extruded to provide a gradual durometer decrease over a defined length of the catheter, or can be extruded to provide as many segments of different durometer as desired. With continuous extrusion, the catheter can be formed to eliminate areas of high stress that are common in many conventional devices at the bonding site where high and low durometer segments are joined together. Such high stress areas may result in breakage and possible separation of the two segments during usage of the device.
In addition to extruding sections of different durometer, continuous extrusion techniques can also be used to provide a device having segments that differ from one another in the type of polymer that is extruded, and in the level of radiopacity. Having segments of different levels of radiopacity in a device enables the physician to more clearly distinguish certain parts of the catheter from other parts under x-ray fluoroscopy. A preferred continuous extrusion process that is useful in preparing the airway exchange catheters of the present invention is a process referred to as Total Intermittent Extrusion (TIE), developed by Putnam Plastics Corporation of Dayville, Conn.
Preferably, airway exchange catheter 10 is also provided with a plurality of indicator markings 20 disposed at selected positions along the length of the catheter. In the embodiment of
In this embodiment, it is preferred that the segments of catheter 70 are formed of the same polymer, wherein the catheter composition differs only in thickness of the catheter wall from one portion of the catheter to another. However, this need not be the case, and the catheter 70 may comprise one or more polymers of the same, or different, durometers bonded or extruded together as described.
It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.
The present patent document claims the benefit of the filing date under 35 U.S.C. § 19(e) of Provisional U.S. Patent Application Ser. No. 60/520,627, filed Nov. 17, 2003, which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60520627 | Nov 2003 | US |
