Abstract: A cuff for measuring volume and change in volume of a body appendage includes a hollow, rigid tube having an inner surface; and a bladder having an inner surface and an outer surface, the ends of the bladder being sealed to the ends of the tube to create an enclosed internal volume between the inner surface of the bladder and the inner surface of the tube and an external volume defined by the outer surface of the bladder and surrounded by the internal volume, the bladder having a normal, relaxed state, in which the internal volume is filled with a fluid and a retracted state in which the fluid is evacuated from the internal volume. Two stiffener ribs placed on the inner surface of the bladder, parallel to each other and to the lengthwise axis of the tube at diametrically opposite positions. A plurality of emitters and detectors arranged in a linear array are embedded in one of the ribs, so as to emit and detect light through the bladder.

Abstract: A cuff for measuring volume and change in volume of a body appendage includes a hollow, rigid tube having an inner surface; and a bladder having an inner surface and an outer surface, the ends of the bladder being sealed to the ends of the tube to create an enclosed internal volume between the inner surface of the bladder and the inner surface of the tube and an external volume defined by the outer surface of the bladder and surrounded by the internal volume, the bladder having a normal, relaxed state, in which the internal volume is filled with a fluid and a retracted state in which the fluid is evacuated from the internal volume. Two stiffener ribs placed on the inner surface of the bladder, parallel to each other and to the lengthwise axis of the tube at diametrically opposite positions. A plurality of emitters and detectors arranged in a linear array are embedded in one of the ribs, so as to emit and detect light through the bladder.

Abstract: An optical sensor includes photoemitter and photodetector elements at multiple spacings (d1, d2) for the purpose of measuring the bulk absorptivity (?) of an area immediately surrounding and including a hemodialysis access site, and the absorptivity (?o) of the tissue itself. At least one photoemitter element and at least one photodetector element are provided, the total number of photoemitter and photodetector elements being at least three. The photoemitter and photodetector elements are collinear and alternatingly arranged, thereby allowing the direct transcutaneous determination of vascular access blood flow.

Abstract: An optical sensor includes photoemitter and photodetector elements at multiple spacings (d1, d2) for the purpose of measuring the bulk absorptivity (?) of an area immediately surrounding and including a hemodialysis access site, and the absorptivity (?o) of the tissue itself. At least one photoemitter element and at least one photodetector element are provided, the total number of photoemitter and photodetector elements being at least three. The photoemitter and photodetector elements are collinear and alternatingly arranged, thereby allowing the direct transcutaneous determination of vascular access blood flow.

Abstract: A system for determining a biologic constituent including hematocrit transcutaneously, noninvasively and continuously. A finger clip assembly includes including at least a pair of emitters and a photodiode in appropriate alignment to enable operation in either a transmissive mode or a reflectance mode. At least one predetermined wavelength of light is passed onto or through body tissues such as a finger, earlobe, or scalp, etc. and attenuation of light at that wavelength is detected. Likewise, the change in blood flow is determined by various techniques including optical, pressure, piezo and strain gage methods. Mathematical manipulation of the detected values compensates for the effects of body tissue and fluid and determines the hematocrit value. If an additional wavelength of light is used which attenuates light substantially differently by oxyhemoglobin and reduced hemoglobin, then the blood oxygen saturation value, independent of hematocrit may be determined.

Abstract: An optical sensor includes a sensing pair of complementary emitter and detector elements for measuring the bulk absorptivity (&agr;) of an area parallel to and including a hemodialysis access site, and a normalizing pair of complementary emitter and detector elements for measuring the absorptivity (&agr;o) of the tissue itself perpendicular to the access site. The pairs of emitter and detector elements define two lines at right angles to each other, and one of the pairs lies to one side of the line defined by the other of the pairs, such that the two pairs of emitter and detector elements form a “T” shape. Indicator dilution techniques are used to measure vascular access flow rates during routine hemodialysis, using the sensor.

Abstract: A cuvette having a pedestal for transmitting light through a relatively thin layer of blood. While the pedestal enables the use of a small path length it also permits the use of a high volume and/or high flow rate conduit. The pedestal further enables methods of determining various blood parameters in which the path length, d, is fixed; i.e., there are little or no pulsatile variations. Hence, the flow-through cuvette accommodates a large range of blood flow rates without any reduction in accuracy of the hematocrit measurement. The pedestal, because of its elliptical shape, does not damage or hemolyze the individual red blood cells as they pass through. A quantitative method for determining changes in blood volume in view of the path length is provided along with a method for measuring a patient's cardiac output and oxygen consumption rate. Cardiac output is obtained by injecting a saline arterial bolus and a saline venous bolus into a patient and measuring the change in hematocrit caused by each bolus.

Abstract: Indicator dilution techniques are used to measure vascular access flow rates during routine hemodialysis. A bolus injection port is used to infuse a specific volume (Vi) of an indicator diluent, such as saline or dye, into the patient cardiovascular circuit by one of the following: 1. Needle injection of a known volume (bolus) of indicator diluent directly into the access site in the presence or absence of the hemodialysis circuit. 2. Infusion of an indicator diluent into the arterial, venous line upstream of the venous needle. 3. Turning the ultrafiltration of the dialysis delivery system from OFF to ON and OFF again over a predetermined time period. 4. In a hemodialysis circuit, turning on the hemodialysis pump and using the priming saline volume as a single saline bolus. A transdermal sensor is used to measure the percent change in a blood parameter.

Abstract: An optical sensor includes photoemitter and photodetector elements at multiple spacings (d1, d2) for the purpose of measuring the bulk absorptivity (&agr;) of an area immediately surrounding and including a hemodialysis access site, and the absorptivity (&agr;o) of the tissue itself. At least one photoemitter element and at least one photodetector element are provided, the total number of photoemitter and photodetector elements being at least three. The photoemitter and photodetector elements are collinear and alternatingly arranged, thereby allowing the direct transcutaneous determination of vascular access blood flow.

Abstract: Systems and methods are provided for noninvasively measuring the levels of urea, blood osmolarity (or Na+), plasma free hemoglobin and tissue water content in a patient's blood or tissue. Light of selected wavelengths is passed through blood or body tissue and the transmitted or reflected light is detected and the detected signals can be electronically compared and manipulated to provide the non-invasive, continuous and quantitative display of a patient's blood urea, blood osmolarity (or Na+), plasma free hemoglobin and tissue water content.

Abstract: A system determines heamtocrit transcutaneously and noninvasively. Disclosed are a finger clip assembly and an earlobe clip assembly, each including at least a pair of emitters and a photodiode in appropriate alignment to enable operation in either a transmissive mode or a reflectance mode. At least two, and preferably three, predetermined wavelengths of light are assed onto or through body tissues such as the finger, earlobe, or scalp, etc. and the extinction of each wavelength is detected. Mathematical manipulation of the detected values compensates for the effects of body tissue and fluid and determines the hematocrit value. If a fourth wavelength of light is used which is extinguished substantially differently by oxyhemoglobin and reduced hemoglobin and which is not substantially extinguished by plasmas, then the blood oxygen saturation value, independent of hematocrit, maybe determined. It is also disclosed how to detect and analyze multiple wavelengths using a logarithmic DC analysis technique.

Abstract: A system for determining a biologic constituent including hematocrit transcutaneously, noninvasively and continuously. A finger clip assembly includes including at least a pair of emitters and a photodiode in appropriate alignment to enable operation in either a transmissive mode or a reflectance mode. At least one predetermined wavelength of light is passed onto or through body tissues such as a finger, earlobe, or scalp, etc. and attenuation of light at that wavelength is detected. Likewise, the change in blood flow is determined by various techniques including optical, pressure, piezo and strain gage methods. Mathematical manipulation of the detected values compensates for the effects of body tissue and fluid and determines the hematocrit value. If an additional wavelength of light is used which attenuates light substantially differently by oxyhemoglobin and reduced hemoglobin, then the blood oxygen saturation value, independent of hematocrit may be determined.