Chemistry: analytical and immunological testing – Optical result – With claimed manipulation of container to effect reaction or...
Patent
1994-08-29
1996-07-23
Housel, James C.
Chemistry: analytical and immunological testing
Optical result
With claimed manipulation of container to effect reaction or...
436 63, 436 66, 422 55, 422 58, 422 8205, 422102, G01N 2103
Patent
active
055389007
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of, and apparatus for, assessing characteristics of fluids. More particularly, it relates to the quantitative assessment of a change in a fluid, e.g. dilution or contamination thereof, or chemical change therein, which change alters the characteristics of the fluid with respect to transmission of radiation therethrough.
The invention is particularly applicable to the assessment of the concentration of a substance present in a fluid, the fluid being relatively transparent to radiation and the substance in the fluid causing an increasing resistance to the passage of radiation through the fluid as its concentration increases. The invention has been devised in relation to the situation wherein the fluid is a liquid and the substance therein is another liquid, such two liquids respectively being substantially transparent to visible light and resistant to the passage of visible light therethrough, such that increasing concentration of the latter liquid in the former liquid causes a progressive decrease in the transparency of the mixed liquids to light. However, it will be appreciated that the principle of the invention is also applicable when the substance whose concentration is required to be assessed is a solid which may form a solution or suspension in the liquid to cause a progressive decrease in the transparency of the liquid with increasing concentration of the solid. The principle of the invention is also applicable to mixtures of gases or vapours wherein a change in the concentration of one such gas or vapour in another causes a change in the transparency of the mixture to light or other radiation, or to the presence of particles in gases, e.g. smoke.
Some examples of applications of the invention are set forth hereafter, but the invention has been devised in relation to a requirement which exists in the medical field, namely that of assessing the quantity of blood contained in a liquid which otherwise comprises wholly or mainly water. A typical situation in which the requirement arises is that where surgery is performed on the prostate gland of a patient. It is important to know how much of the patient's blood is lost in order to assess the need for replacement thereof by transfusion, but direct measurement of such blood loss is extremely difficult because, although fluid can be collected by a catheter inserted into the bladder of the patient, such fluid comprises blood mixed with some urine from the patient's bladder and irrigation fluid, which is mainly water, introduced into the patient's bladder. The drained fluid, collected in a catheter bag, can be subjected to laboratory analysis to determine the concentration of blood therein, and thus the requirement for replacement of blood, but such analysis is time consuming and expensive. Furthermore, highly accurate analysis is not necessary for the immediate purpose of assessing the requirement for replacement blood. There is thus a requirement for a rapid and reasonably accurate assessment of the concentration of blood in the drained fluid to be made; then, since the total volume of fluid in a catheter bag is readily measured, it is possible to make a virtually immediate assessment of any requirement for blood replacement.
It is one object of the present invention to meet the above described requirement for assessment of concentration of blood in fluid drained from a patient. However, it will be appreciated that the principle of the invention, in meeting this requirement, is applicable far more widely, and examples of such application are referred to hereafter.
According to one aspect of the present invention, I provide apparatus for assessing a characteristic of a fluid in respect of its effect on the transmission of radiation through the fluid, comprising a chamber for receiving the fluid, said chamber including wall portions arranged for passage of radiation therethrough and through fluid therebetween and said wall portions being spaced differently from one another at different parts of the chamber so that the radiat
REFERENCES:
Fiddik et al. "A variable pathlength . . . " Journal of Physics E. Scientific Instruments vol. 21, No. 11, Nov. 1988.
Airsschfeld "Lens and Wedge . . . " Applied Spectroscopy vol. 39, No. 3 Jun. 1985.
JP Abstract vol. 009, No. 24 (p. 331) 31 Jan. 1985 Hitachi Densenkk.
Freed Rachel Heather
Housel James C.
Naked Eye Limited
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