Abstract: A measuring apparatus based on the NDIR process. Pulsed infrared light traverses in two parallel optical beams (3, 4) initially a cell (6) filled with .sup.13 CO.sub.2 and a cell (7) filled with .sup.12 CO.sub.2 and then, in parallel, two cells (8, 9) which are filled with the gas sample to be analyzed. Cells (8, 9) together with a capacitor microphone (15) serving as the pressure converting means form an optopneumatic receiver (17). By regulating the pressure in cell (6) the minimum of the pressure conversion signal is investigated and related to a correspondingly obtained reference value. The simply constructed apparatus permits a .sup.13 CO.sub.2 breathing test to be performed inexpensively.

Abstract: An apparatus for the biofeedback control of body functions is proposed having at least one sensor for detecting biological body functions, a data memory for storing comparison values, a control unit or microprocessor (9, 16) and a therapy member, the control means (9, 16) activating the therapy system as a function of the measured values detected by the sensor and the comparison values. The therapy systems has a pump for the intravenous, intra-arterial, oral or intraluminal administration and a drug reservoir connected to the pump. The control unit and/or therapy means is provided with a memory, which stores the therapy objectives for the body functions with associated drug doses as a function of the detected measured values and comparison values.

Abstract: In the portable instrument an intragastric probe, with a combined pH-electrode at its tip, measures pH values over a long time period and stores, calculates, evaluates, indicates (at any selected time) and prints out the data. At any particular time, both the actual pH value at that moment and all stored data up to that moment are immediately available to the physician. The small size of the apparatus does not interfere with the normal activity of the patient even over a long time period. The apparatus allows the individual diurnal rhythm of acid secretion to be observed, including the effects thereon of food (and dietary changes, smoking, alcohol, coffee, and drugs, as they occur.