Surgery – Diagnostic testing – Liquid collection
Reexamination Certificate
1999-08-12
2001-03-27
O'Connor, Cary (Department: 3736)
Surgery
Diagnostic testing
Liquid collection
C600S309000, C128S898000
Reexamination Certificate
active
06206840
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a method for the identification of a liquid secreted by a living subject, particularly amniotic fluid, and is also directed to an apparatus for implementation of the method.
2. Description of the Prior Art
During a pregnancy, a premature rupture of the amnion can occur, which is the loss of amniotic fluid with opening the water bag without the uterus being in labor. The clinical reason for a premature rupture of the amnion is that a path through the vagina between the exterior environment and the intra-uterine embryonic region is established, and as a result the access of bacteria with subsequent intra-uterine infection becomes possible. An intra-uterine infection can be life-threatening for the child as well as for the mother, and moreover can lead to permanent sterility.
Whereas manifest rupture of the amnion with some loss of amniotic fluid raises no diagnostic problems, a so-called high rupture of the amnion often can be detected only with great difficulty. Patients report a loss of fluid, but it is not clear whether it is amniotic fluid, urine or vaginal secretion.
The detection of premature rupture of the amnion is of substantial clinical significance in natal care. The risks that are associated with an unrecognized rupture of the amnion are serious and life-threatening under certain circumstances. Particularly in the early stages of pregnancy, they can result in a premature birth with all of the accompanying phenomena. The reliable exclusion of a premature rupture of the amnion is likewise of great significance since corresponding symptoms (loss of fluid) are frequently observed and unnecessary, non-temporary admission into a hospital with the corresponding discomfort and cost often arises.
Various methods have been utilized for detecting amniotic fluid. These are essentially based on the detection of substances that are contained in high concentration in amniotic fluid but do not occur in vaginal secretion. Included, for example, are prolacitin, human choriongonadotropine (HCG), alpha-feto-protein (AFP) and other pregnancy-specific proteins. The problems in detecting these substances are due to the fact that these substances very quickly decompose in acidic vaginal secretion and then no longer can be detected; and the detection of these proteins is often not simple to implement in terms of methodology.
A further possibility for diagnosis is to conduct ultrasound examinations. An attempt is thereby made to provoke a discharge of amniotic fluid toward the outside along the water bag by pressing and shaking the lower torso. If such a discharge occurs it should be perceptible in the ultrasound image.
Another possibility for diagnosis is to make use of the fact that the amniotic fluid has an alkaline pH value. This is checked with a litmus test of the vaginal fluid.
German PS 37 06 372 discloses a method and an apparatus for signaling birth in animals, particularly in dogs. The method identifies the suddenly-increasing atmospheric humidity which occurs due to the amniotic fluid being released at birth, and an acoustic and/or optical signal is triggered immediately thereafter. An apparatus for the implementation of the method has a humidistat arranged within the animals's habitat, such as a doghouse or the like, preferably in the ceiling region, this being connected to an electrically actuatable evaluation device that registers sudden changes in atmospheric humidity. This evaluation device is connected in pulse-generating fashion to a signal sensor provided outside the habitat. This method and this device, however, are not suitable for identifying a liquid secreted by a living subject. Since living subjects are composed of 70-80% water, they are always moist. The presence of moisture is not characteristic of a specific, secreted fluid; rather, no distinction can be made as to whether the fluid, even if detected, is amniotic fluid, urine or vaginal secretion.
The term “electronic nose” describes sensor systems that are close to the human olfactory sense in terms of their functioning. By contrast to gas chromatography or mass spectrometry, they do not detect individual components of a gas but detect aggregate parameters. A so-called fingerprint of the scent is registered. The results are differently presented dependent on the type of evaluation.
The article by M. A. Craven, J. W. Gardner, P. N. Bartlett, “Electronic Noses—Development and Future Prospects”, which appeared in Trends in Analytical Chemistry, Vol. 355 (1996), pp. 486-493, indicates that commercial devices that are called electronic noses are now being utilized in a number of industrial fields such as food processing, water handling, and brewing. Medical diagnostics is also cited therein as a possible, future field of employment of electronic noses.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and an apparatus with which a liquid secreted by a life form, particularly amniotic fluid, can be identified in a simple way.
This object is achieved in a method in accordance with the invention wherein the fluid is identified by its characteristic, volatile constituents. This is based on the experience that such fluids have a characteristic odor independently of the individual. Differentiated according to their contents, the fluids have a specific vapor pressure, so that characteristic gases in the ambient air can be detected. Gas analysis is simpler compared to analysis of fluids because the characterizing constituents in the complex but uncharacteristic liquid matrix are difficult to detect and because a specimen preparation is often additionally required following the taking of a specimen, given analysis of liquids.
Fundamentally, every individual type of gas, or the constituents and composition thereof, can be measured by utilizing specific gas sensors. Many specific gas sensors are necessary in order to recognize a complex aroma that is composed of many constituents or analytes in this way. In addition to the complicated technical realization of the sensors, a number of sensors are needed, these then in turn being utilized in toto only for characterizing a few scents. Moreover, it has generally not yet been exactly scientifically documented how many and which chemical substances yield a complex aroma. Nonetheless, such an approach makes sense where the odor is caused by one or a few chemical substances recognized for this odor such as, for example, given a diabetic coma where acetone and ketone compounds are released.
Dependent on the application, concentrating the analyte can be necessary given an analyte content which is too low. This is achieved by an adsorption tube through which the specimen is conducted across an adsorbent. The analytes are thereby captured therein. By means of a following thermal desorption, the substances are released in a smaller volume, as the result of which the concentration is increased. The sensitivity of the overall system can be improved in this way.
In an embodiment of the method, the characteristic volatile constituents are supplied to a number of sensors which are analyte-non-specific, that have different sensor behavior compared to one another, and measured signals of the sensors generated by the characteristic volatile constituents are supplied to a computer for typing and clustering. An arrangement of analyte-non-specific sensors with a corresponding evaluation unit is also referred to as a electronic nose. When a number of such sensors are utilized, typically 8 through 32, each exhibiting different sensor behavior compared to one another, one analyte can produced different measured values or sensor responses, so that a fingerprint, so to speak, of the respective analyte is obtained dependent on the odor. Ideally, the sensors cover a broad spectrum of chemical properties of the gas analytes such as, for example, the molecule size, the redox behavior, etc., so that no redundant information is measured by different sensors. An exact fingerprint of the
Abraham-Fuchs Klaus
Binder Helge
Schmidt Kai-Uwe
Tork Joachim
Wildt Ludwig
Marmor II Charles
O'Connor Cary
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
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