Abstract: A diagnostic apparatus includes light sources which emit near infrared light rays of different wavelengths. The light rays are introduced into human brain to be subjected to diagnosis and the light rays transmitted through the brain are picked up. There are provided a first detector which detects occurrences of respirations of the subject and outputs a respiration signal, and a second detector which detects occurrences of heartbeats of the subject and outputs a heartbeat signal. The light transmitted through the brain is derived in synchronism with both the respiration signal and the heartbeat signal and first and second modulated light transmission signals are produced which are respectively modulated by the respiration signal and the heartbeat signal. The first and second modulated light transmission signals are separately analyzed to provide variations in concentration of oxygenated media .DELTA.X.sub.02 and disoxygenated media .DELTA.X contained in venous and arterial blood of the brain, respectively.

Abstract: A tissue oxygen measuring system enabling the automatic and continuous measurement of diagnosing items including cerebral blood flow, cerebral blood volume, and response of cerebral blood volume in arterial carbon dioxide tension uses an oxygen measuring system based on near infrared spectroscopy, a pulse oximeter, and an arterial carbon dioxide tension measuring unit. A gas blending unit is employed before a ventilator or face mask to control the ventilator so that a rate of a quantity of oxygen and/or a quantity of carbon dioxide to be blended in the air is changed at predetermined intervals. Trigger signals are produced in synchronism with the changes of the gaseous contents of the air, and parameters for computing information regarding the diagnosing items are measured in response to the trigger signals. With the repetitive measurements of the parameters, a signal-to-noise ratio can be improved by averaging the data and erroneous data can easily be identified.

Abstract: An apparatus for obtaining information on the interior of an object, comprising irradiating elements for applying an electromagnetic wave or ultrasonic wave to an object being measured, detecting elements for detecting the electromagnetic wave or ultrasonic wave passed through and scattered inside the object, a holder for supporting the irradiating elements and the detecting elements in such a manner that the irradiating elements and the detecting elements are slidable and position detecting elements for detecting the position data of the irradiating elements and the detecting means with respect to the holder.

Abstract: The calibration of a polarographic oxygen sensor (20) at zero oxygen concentration is accomplished by providing an oxygen-free liquid environment at the sensor active surface. This is accomplished electrolytically by depleting a thin film of electrolyte (24) of oxygen to zero concentration with an oxygen-reducing cathode (6), and complementary anode (4), connected via a battery (10) and switch (12). The sensor (20) is placed into close proximity with the electrodes (4,6) and the oxygen in the electrolyte (24) reduced while its concentration is measured by the sensor (20). A low steady-state signal for the sensor provides the zero oxygen concentration calibration point.

Abstract: The determination of the concentration of compounds such as CO.sub.2 having an influence on the pH of a medium during polarography is described. Characteristics of polarograms when obtained in unbuffered electrolytes (the polarogram plateau slope position of the upper knee and half-wave potential thereof) are pH-sensitive. These can be detected electronically and signals processed to provide a measure of such concentrations.In one preferred embodiment (FIG. 2) a miniature pO.sub.2 polarographic sensor has cathode channels (A) and (B) biased respecitvely at -750 mV and -950 mV. The output of channel (A) provides pO.sub.2 as in normal polarography. The output of (B) is divided (6) and further corrected for pO.sub.2 (8,10) to provide pCO.sub.2.The apparatus is especially useful for simultaneous pO.sub.2, pCO.sub.2 monitoring in physiological fluids without the need for a separate pCO.sub.2 sensor.

Abstract: A transcutaneous gas sensor for application to the body surface of a patient is provided. The sensor includes a sensing electrode having an exposed surface region which, in use, is applied to the body surface of the patient with an electrolyte layer between the electrode and the patient's body. Gas which has diffused through the patient's body from his blood to the body surface results in an electrochemical reaction taking place at the exposed surface region of the electrode. This exposed surface region can consist of an individual surface area, or several such surface areas. In one embodiment, the surface area or areas are arranged and are of a configuration such as to have associated therewith an imaginary envelope of greater area than the total area occupied by the individual surface area or areas; with such an arrangement, the surface area or areas have the same or similar widths.

Abstract: An instrument for use in the measurement of gases in body fluids comprises a flexible catheter having an inner tube within an outer tube, the tubes being of such diameters that there is a substantially cylindrical passage between the tubes which can be evacuated or flushed with a non-interfering gas. Spacers can be provided in the passage, such as radial webs or a single or double helix filament.

Abstract: A transcutaneous probe for causing oxygen and other gases or vapors carried in the bloodstream of a mammal to be extracted from the blood through the skin and passed to a device, such as a mass spectrometer, for analyzing the extracted gas. The probe has a boundary wall intended to be placed in contact with the skin comprising a first layer of gas permeable material and a second layer of perforate or porous gas-impermeable material in intimate contact with the first, the size and distribution of the perforations or pores in the second layer being such that the wall has a substantially uniform extrinsic macropermeability which is significantly lower than the inherent permeability of the first layer alone and such that in use, gas passes into the perforations or pores of the second layer from respective volumes of tissue which do not substantially overlap.