Surgery – Diagnostic testing – Respiratory
Reexamination Certificate
1999-08-10
2001-01-23
Cohen, Lee (Department: 3739)
Surgery
Diagnostic testing
Respiratory
C073S861520
Reexamination Certificate
active
06176833
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to air tubes for use with spirometers, and to spirometers using such air tubes. More particularly, the present invention relates to air tubes which are disposable and at least partially biodegradable, and to spirometers, preferably differential pressure spirometers, which employ such air tubes.
Spirometers are devices used to measure the volume and flow rate of gas exhaled by a user or patient, for example, a human being. These measurements are important for physiological studies and for diagnostic analysis of the pulmonary performance of the spirometer user. For example, the effects of various medicines used to treat patients with pulmonary or asthmatic problems can be analyzed by monitoring the volume and flow rate of gas exhaled before and after the administration of medication. Several devices are available on the market which are known as pneumotachs, such as the Fleisch Pneumotach. These devices depend on a laminar air flow past a resistance element. Other spirometers employ more sophisticated electronics so that laminar flow is not needed.
Measuring the pressure difference or differential pressure of exhaled gas across an element which creates or causes the pressure difference is the basis for differential pressure spirometers. In such differential pressure spirometers, it is important that the air tube (pneumotach) be precisely configured and positioned, for example, relative to the pressure sensing and electronics systems of the spirometers so that measurements can be reliably and reproducably made. Such precisely configured pneumotachs, rather than being disposable, are made out of metals or durable plastics to be long lasting and effective after many uses without structural degradation. See, for example, Waterson et al U.S. Pat. No. 5,137,026, the disclosure of which is hereby incorporated in its entirety by reference herein.
Since most spirometers involve passing exhaled gas directly from the respiratory system of a user into the instrument for measuring, one important complication of using such devices is contamination from one patient to another patient if the same spirometer is employed by both.
Various approaches to overcoming this contamination problem have been suggested. A particularly popular approach is to use a disposable mouthpiece and filter over the inlet to the spirometer. The patient using the spirometer comes in contact only with the mouthpiece and is able, at least in theory, to avoid contaminating the remainder of the device. Drawbacks to this approach include the relative expense of such mouthpieces/filters, and the relative inefficiency of such systems.
Another approach to overcoming this contamination problem is to sterilize the portion or portions of the spirometer which come in contact with the user and/or exhaled air. Drawbacks to this approach include having to spend additional capital on sterilization equipment, having to monitor the operation and efficacy of the sterilization equipment, and having to purchase relatively durable and expensive spirometers to withstand the sterilization procedures.
A third alternative that has been suggested is the use of disposable spirometer components. See, for example, Norlien et al U.S. Pat. No. 5,038,773; Acorn et al U.S. Pat. No. 5,305,762; Karpowicz U.S. Patent Des. 272,184; Boehringer et al U.S. Pat. No. 4,807,641; and Bieganski et al U.S. Pat. No. 4,905,709. Such previous disposable spirometer components have been made out of durable plastics or medical grade metals so that, even though they are disposable, the cost of producing such components is relatively high. In addition, such disposable components are relatively difficult to dispose of, for example, because they are made of durable and long lasting materials.
It would be advantageous to provide spirometers and spirometer components which avoid cross-patient contamination and which can be economically, conveniently and effectively produced and used.
SUMMARY OF THE INVENTION
New air tubes for use in spirometers and spirometers including such air tubes have been discovered. The present air tubes are disposable so that after one patient uses the air tube it is removed from the spirometer and is disposed of. Importantly, the air tube is at least partially, preferably completely, biodegradable.
As used herein, the term “biodegradable” means that the component or material is decomposable into more environmentally acceptable components, such as carbon dioxide, water, methane and the like, by natural biological processes, such as microbial action, for example, if exposed to typical landfill conditions, in no more than five years, preferably no more than three years, and still more preferably no more than one year.
Having the air tube biodegradable provides substantial advantages. First, when the air tube is disposed of, the burden on the environment of such disposal is reduced relative to, for example, a non-biodegradable air tube, such as those made out of conventional plastics or metals. In addition, because the air tube is biodegradable, it can be made of materials which are inexpensive and plentiful (readily available). Thus, the present air tubes are relatively inexpensive, easy and straightforward to produce, requiring little or no sophisticated production equipment. Since the present air tubes can be made economically, replacing a used air tube with a new air tube is done without substantial economic impact. In addition, the present air tubes can be replaced in the spirometer very easily. These advantages promote operator compliance in that the spirometer operator (for example, the care provider or the patient operating the spirometer) is more likely to change the present air tubes after each patient or treatment, thus reducing the risks of contamination and the spread of diseases, for example, tuberculosis and other respiratory system disorders, AIDS, other systemic conditions and the like.
Spirometers employing the present air tubes provide cost effective, reliable and reproducible (from air tube to air tube) measurements of the pulmonary performance of the user, with reduced risk of contamination. In short, the present disposable, biodegradable spirometer air tubes are inexpensive and easy to produce to acceptably precise specifications (for reproducible performance), are effective and reliable in use, and are conveniently and effectively disposed of in an environmentally acceptable or safe manner to reduce the risks of contamination caused by spirometer use.
In one broad aspect, the present invention is directed to air tubes for use in spirometers. The present air tubes comprise a tubular portion which defines an open inlet, an open, preferably opposing, outlet and a hollow space therebetween. The tubular portion is sized and adapted to be removably coupled to the housing of a spirometer. The air tube is disposable, i.e., can be removed or decoupled from the spirometer housing and disposed of without disposing of the housing. At least a portion, preferably at least major portion, that is at least about 50% by weight, and more preferably substantially all, of the tubular portion is biodegradable. Preferably, the open inlet is sized and adapted to be received in the mouth of the user of the spirometer. Thus, this open inlet and the area of the tubular portion near the open inlet act as a mouthpiece for the spirometer so that the user or patient using the spirometer can exhale into the air tube directly through the open inlet. No separate and/or specially configured (relative expensive) mouthpiece/filter is needed when using the present air tubes.
In addition, the present air tubes include a resistive element which is located in the hollow space of the tubular portion. This resistive element is sized and adapted to cause a pressure difference or differential as air flows in the hollow space across this element. Preferably at least a portion, more preferably at least major portion, and still more preferably substantially all, of the resistive element is biodegradable.
Two through ports
Cohen Lee
Desert Moon Development
Stout, Uxa, Buyan & Mullins
Uxa Frank J.
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