Abstract: The invention relates to pulse oximeters used to measure blood oxygenation. The current trend towards lower power consumption has brought a problem of erroneous readings caused by intrachannel crosstalk, i.e. errors due to the coupling of undesired capacitive, inductive, or conductive (resistive) pulse power from the emitting side of the pulse oximeter directly to the detecting side of the oximeter. The pulse oximeter of the invention is therefore provided with means for detecting whether intrachannel crosstalk is present and whether it will cause erroneous results in the oxygenation measurements. The pulse oximeter is preferably further provided with means for eliminating intrachannel crosstalk which are adapted to control the measurement so that measurement signals can be obtained which are substantially void of crosstalk components.

Abstract: The invention relates to monitoring the neurological state of a patient. In the method invention, both cortex- and subcortex-related biosignal data are obtained from the patient, the subcortex-related biosignal data including at least bioimpedance signal data. A first indicator is calculated based on the cortex-related biosignal data, the first indicator being indicative of cortical activity in the patient and a set of indicators is calculated based on the subcortex-related biosignal data indicative of subcortical activity in the patient, the set of indicators including at least a second indicator calculated based on the bioimpedance signal data. A composite indication is then produced based on the first indicator and on the set of indicators. The invention also concerns an apparatus and a sensor for monitoring the neurological state of the patient.

Abstract: The invention concerns a method and an apparatus for monitoring a condition of a patient under anesthesia or sedation. For this purpose there is a sensor for acquiring a signal that represents peripheral cardiovascular flow in the patient. Successive heart beat pulses are detected and predetermined pulse wave parameters are measured repeatedly in said signal, and predefined pulse wave parameters within said heart beat pulses are measured, too. At first, said predetermined pulse wave parameters in a number of successive heart beat pulses are compared in respect to possible occurrence of a substantial alteration. At second, if the alteration is noticed, a statistical reference value is calculated by deriving values from at least said predefined pulse wave parameters, and the change(s) between at least one predefined pulse wave parameter and said reference value is quantified. The results and/or intermediate results are finally displayed and/or recorded.

Abstract: The invention relates to the calibration of a pulse oximeter intended for non-invasively determining the amount of at least two light-absorbing substances in the blood of a subject. In order to bring about a solution by means of which the effects caused by the tissue of the subject can be taken into account in connection with the calibration of a pulse oximeter, initial characterization measurements are carried out for a pulse oximeter calibrated under nominal conditions. Based on the characterization measurements, nominal characteristics are established describing the conditions under which nominal calibration has been defined, and reference data indicating the nominal characteristics are stored. In-vivo measurements are then performed on living tissue and based on the in-vivo measurements and the reference data stored, tissue-induced changes in the nominal characteristics are determined.

Abstract: A method and system for combining active and passive neuromonitoring methods to measure biopotential signals in sedated ICU patients over the entire range of sedation from fully alert to the suppression of EEG. The system utilizes an integrated sensor that includes a sound generator and a plurality of EEG electrodes on a single, lightweight disposable component. The method of the present invention utilizes a control unit for switching between active and passive monitoring methods, depending upon the level of sedation. The control unit displays the results of active monitoring during levels of consciousness and light sedation and displays the results of passive monitoring during levels of deep sedation.

Abstract: The invention relates to a method for monitoring a condition of a patient under anesthesia or sedation, whereupon one, two, three or more signals are acquired, and the signal(s) represent(s) cardiovascular and/or combined electrical biopotential on skull activity of the patient. From said signal or signals are derived or calculated at least two parameter values related to a quantity like waveform amplitude, waveform periodicity, waveform morphology, waveform variability, energy, power, signal complexity and frequency content. A predetermined mathematical index for probability of patient comfort is used, in which function said parameters are variables, and successively changing probability index values of said mathematical index is calculated.

Abstract: The invention relates to the calibration of a pulse oximeter intended for non-invasively determining the amount of at least two light-absorbing substances in the blood of a subject. In order to bring about a solution by means of which the effects caused by the tissue of the subject can be taken into account in connection with the calibration of a pulse oximeter, initial characterization measurements are carried out for a pulse oximeter calibrated under nominal conditions. Based on the characterization measurements, nominal characteristics are established describing the conditions under which nominal calibration has been defined, and reference data indicating the nominal characteristics are stored. In-vivo measurements are then performed on living tissue and based on the in-vivo measurements and the reference data stored, tissue-induced changes in the nominal characteristics are determined.

Abstract: A radiation source assembly and transducer incorporating same are suitable for use in measuring spectral absorption properties of a substance to be analyzed, such as a gas. The radiation source assembly has an optical axis. A measuring radiation source provides radiation in the direction of the axis and a reference radiation source provides radiation in the direction of the axis. An optical diffuser is spaced from the radiation sources along the axis. Radiation from the measuring radiation source and radiation from the reference radiation source are applied to the diffuser and the diffuser forms an exiting radiation beam for the assembly from the radiation of the measuring radiation source and reference radiation source. The exiting radiation beam extends along the axis.

Abstract: The invention relates to the calibration of a pulse oximeter intended for non-invasively determining the amount of at least two light absorbing substances in the blood of a subject. In order to take human variability into account, the calibration is based on an invariant which is a quotient of two pseudo-isobestic signals. Each pseudo-isobestic signal is a weighted sum of two signals, and the weighted sum is theoretically independent of the relative concentrations of said substances in the blood of the subject. By using theoretical values of the invariant on the one hand, and values based on in-vivo measurements on the other hand, the calibration curve of the pulse oximeter is adapted to the characteristics of each individual patient.

Abstract: The invention relates to pulse oximeters used to measure blood oxygenation. The current trend towards lower power consumption has brought a problem of erroneous readings caused by intrachannel crosstalk, i.e. errors due to the coupling of undesired capacitive, inductive, or conductive (resistive) pulse power from the emitting side of the pulse oximeter directly to the detecting side of the oximeter. The pulse oximeter of the invention is therefore provided with means for detecting whether intrachannel crosstalk is present and whether it will cause erroneous results in the oxygenation measurements. The pulse oximeter is preferably further provided with means for eliminating intrachannel crosstalk which are adapted to control the measurement so that measurement signals can be obtained which are substantially void of crosstalk components.

Abstract: The invention relates to the calibration of a pulse oximeter intended for non-invasively determining the amount of at least two light absorbing substances in the blood of a subject. In order to take human variability into account, the calibration is based on an invariant which is a quotient of two pseudo-isobestic signals. Each pseudo-isobestic signal is a weighted sum of two signals, and the weighted sum is theoretically independent of the relative concentrations of said substances in the blood of the subject. By using theoretical values of the invariant on the one hand, and values based on in-vivo measurements on the other hand, the calibration curve of the pulse oximeter is adapted to the characteristics of each individual patient.

Abstract: A sensor device and a method for non-dispersive analysis of gas mixtures for determining the concentration of one gas component contained therein, whose absorbency may be influenced as a result of collision broadening by other components contained in a gas mixture (GC). The device includes: a measuring chamber (5), containing the gas mixture; a radiation source (4), emitting radiation (15) through the chamber; detector (10, 14, 16) for receiving radiation passed through the chamber; optical bandpass filters (9a-c) positioned between the detectors and the radiation source, the detectors being coupled with measuring ducts (1-3) or measuring cycles. An optical gas filter (11), contains said gas component or a mixture thereof and is located between the detector and the radiation source. From the first measuring duct is obtained a first signal (S1) and from the second measuring duct is obtained a second signal (S2) relating to radiation also passed through the optical gas filter.

Abstract: The invention relates to a procedure for determining the relative concentration or composition of different kinds of haemoglobin, such as oxyhaemoglobin, deoxyhaemoglobin and dyshaemoglobins, and/or dye components contained in blood in a non-invasive manner using the light absorption caused by different haemoglobin varieties and/or dye components, in which procedure light signals are transmitted at at least two predetermined wavelengths to a tissue comprised in the patient's blood circulation, the light signal transmitted through the target under measurement and/or reflected from it is received and the proportion of the intensity of the pulsating light signal received at each wavelength is determined in relation to the total intensity of the light transmitted through the tissue or reflected from the tissue.

Abstract: A radiation source assembly and transducer incorporating same are suitable for use in measuring spectral absorption properties of a substance to be analyzed, such as a gas. The radiation source assembly has an optical axis. A measuring radiation source provides radiation in the direction of the axis and a reference radiation source provides radiation in the direction of the axis. An optical diffuser is spaced from the radiation sources along the axis. Radiation from the measuring radiation source and radiation from the reference radiation source are applied to the diffuser and the diffuser forms an exiting radiation beam for the assembly from the radiation of the measuring radiation source and reference radiation source. The exiting radiation beam extends along the axis.