Abstract: The apparatus for monitoring respiration comprises a photoplethysmographic sensor whose LED transmitter element(s) is/(are) excited by a monitoring unit with a specified control power and/or control signal sequence or frequency. By means of a signal processing unit, both the frequency and depth of respiration can be measured, as can the pulse frequency or oxygen saturation of the peripheral blood. The use of such an apparatus guarantees significantly more reliable monitoring of respiration than the impedance pneumographic methods of the prior art.

Abstract: This invention provides a polarographic/amperometric measuring sensor, particularly useful for transcutaneous determination of the oxygen partial pressure (tcpO.sub.2) in the blood by means of a Clark-type electrode arrangement. According to the invention the counter electrode, preferably made of a noble metal, is disposed about the insulating material encasing the working electrode and is preferably made of the same noble metal as the working electrode. The measuring sensor can also be provided with a pH electrode for simultaneous determination of the carbon dioxide partial pressure (tcpCO.sub.2) in the blood.

Abstract: Disclosed herein is a retainer assembly for applying a membrane to a physiological sensing unit for the transcutaneous determination of the magnitude of physiological quantities, particularly for measuring the partial pressure of gases in blood or the like. The assembly constitutes a preassembly of a membrane, with a clamping ring accommodating the membrane and having an annular recess receiving the rim of the membrane. The clamping ring has a lip in the form of an inwardly protruding annular edge for removably securing the clamping ring together with the membrane to the sensing unit by virtue of the lip resiliently snapping into a peripheral groove of the sensing unit, the lip defining the periphery of the annular recess. A retainer element is provided for temporarily and removably assembling the membrane with the clamping ring prior to assembly with the sensing unit.

Abstract: Disclosed herein is a physiological, electrically heated, thermostatically controlled sensing unit of the type used in the medical field for measuring blood contents, such as oxygen. A typical unit comprises a housing for application to the skin of a living being, an electric heater element within the housing, and a temperature-responsive switching circuit, also accommodated within the housing. The switching circuit automatically disconnects a power supply to the heater element when the skin temperature exceeds an adjustable predetermined threshold level. The power supply for the switching circuit is directly connected to the power supply for the heater element within the housing.

Abstract: Disclosed herein is a method for the calibration of a sensing unit for determining the partial pressure of oxygen in contact with the sensing unit. The method is of the type using a zero-calibration solution in which the partial pressure of oxygen is maintained at zero by virtue of a binding agent present in the solution for chemically combining with the oxygen. The essential steps of the method include adding to the solution a color indicator for indicating that the zero-calibration solution contains unspent binding agent, contacting the sensing unit with the zero-calibration solution containing the unspent binding agent and the color indicator, energizing the sensing unit, and adjusting the sensing unit until it indicates zero concentration.The invention also compasses within its scope a calibration agent for use in the performance of the method for supplying the zero-calibration solution upon dissolution in water, as well as a container for storing the zero-calibration solution.

Abstract: A sensor for transcutaneous measurement of physiological phenomena of living tissues is provided with a thermostatically-controlled electric heater. The purpose of the heater is to induce local hyperemia to enable operation of the sensor. The heater is thermostatically controlled. An independent temperature sensor is provided to disable the heater in the event of catastrophic failure of the thermostat circuit.