Abstract: A method, arrangement and apparatus for assessing fluid balance status of a subject are disclosed. At least one physiological parameter responsive to blood volume changes in the subject is determined and a predetermined change in the ventilation of the subject is produced. The response that the predetermined change of ventilation causes in at least one of the at least one physiological parameter is then determined, thereby to obtain at least one measure of change. The fluid balance status of the subject may be assessed based on the at least one measure of change. The subject is typically connected to a ventilator and the predetermined change is produced by controlling the ventilator.

Abstract: A measuring apparatus, a physiological sensor, and an interface unit for determining blood parameters of a subject are disclosed. The sensor comprises an emitter unit comprising a first plurality of emitter elements configured to emit radiation at a second plurality of wavelengths and a detector unit configured to receive radiation generated by the emitter elements and transmitted through the tissue of the subject, wherein the detector unit is further configured to produce electric measurement signals indicative of absorption caused by the blood of the subject.

Abstract: A measuring apparatus, a physiological sensor, and an interface unit for determining blood parameters of a subject are disclosed. The sensor comprises an emitter unit comprising a first plurality of emitter elements configured to emit radiation at a second plurality of wavelengths and a detector unit configured to receive radiation generated by the emitter unit and transmitted through tissue of the subject. The sensor further comprises a sensor memory storing sensor-specific information about the sensor unit, wherein the sensor-specific information includes at least calibration data for a given measurement mode, and a memory access interface for enabling an entity external to the sensor to update at least part of the sensor-specific information in a sensor ability update process, thereby to update ability of the sensor unit to operate in the given measurement mode.

Abstract: A method and apparatus for monitoring fluid balance status of a subject are disclosed. A hemoglobin measure indicative of hemoglobin concentration in the blood of a subject and at least one physiological parameter responsive to blood volume changes in the subject are determined and concurrent behavior of the hemoglobin measure and the at least one physiological parameter is indicated to a user, thereby to give an indication of fluid balance status of the subject. The cause and/or reliability of the fluid balance status may also be indicated.

Abstract: A method, arrangement and sensor for monitoring blood status of a subject are disclosed. In-vivo measurement signals indicative of absorption caused by blood are acquired at a plurality of measurement wavelengths. Based on the in-vivo measurement signals, successive values are determined for a hemoglobin parameter indicative of the concentration of hemoglobin in the blood of the subject and the blood volume status of the subject is monitored based on the successive values. The monitoring may involve determining the absolute value of the blood volume or relative changes in the blood volume. In one embodiment, the absolute value of the blood volume is indicated continuously together with hemoglobin concentration and composition.

Abstract: The invention relates to the determination of the clinical stress of a subject. In order to bring about an uncomplicated and cost-effective method for monitoring the stress status of a subject, plethysmographic signal data is acquired from the subject and a first measurement signal is derived, which is indicative of a predetemined feature of the respiration modulation appearing in the said signal data. An index signal is then formed based on the first measurement signal and the index signal is employed as an index indicative of the clinical stress of the subject.

Abstract: The invention relates to a method and arrangement for monitoring the state of the autonomous nervous system (ANS) of a patient. A first measurement signal is acquired from a patient, the first measurement signal representing a physiological signal measured from the patient. In order to enable real-time monitoring of the state of the ANS, a second measurement signal indicative of a respiration rhythm of the patient is acquired and at least one indicator signal is generated by means of the first and second measurement signals. The at least one indicator signal may then be used to obtain an indication of the state of the autonomous nervous system of the patient.

Abstract: The invention relates to a method of calibrating a pulse oximeter, in which the effects caused by tissue of a subject can be taken into account. A detector output signal is measured when living tissue of the subject is present between emitters and the detector in a sensor. Nominal calibration and nominal calibration characteristics are read from a memory, whereupon values for the same nominal characteristics for the sensor on living tissue of the subject are established using the detector output signal. Then, changes in the nominal calibration characteristics induced by the living tissue are calculated and a subject-specific calibration is formed by correcting the nominal calibration with the changes. Finally, the hemoglobin fractions are solved using the corrected nominal calibration.

Abstract: In order to provide a non-invasive and continuous concentration measurement with the technology of standard pulse oximeters, an a priori relationship is created, through an in-vivo tissue model including a nominal estimate of a tissue parameter indicative of the concentration of a blood substance. The a priori relationship is indicative of the effect of tissue on in-vivo measurement signals at a plurality of wavelengths, the in-vivo measurement signals being indicative of absorption caused by pulsed arterial blood. In-vivo measurement signals are acquired from in-vivo tissue at the plurality of wavelengths and a specific value of the tissue parameter is determined based on the a priori relationship, the specific value being such that it yields the effect of the in-vivo tissue on the in-vivo measurement signals consistent for the plurality of wavelengths. The specific value then represents the concentration of the substance in the blood.

Abstract: The invention relates to the determination of a diagnostic index indicative of the clinical state, especially nociceptive state, of a subject. In order to improve the quality of the determination process, desired input signals derived from the subject are monitored and the quality of the process is improved based on the monitoring. This is implemented by increasing user awareness of the reliability of the index or by controlling the measurement set-up. Quality information indicative of the reliability of the current index values may be produced based on the input signals. The quality information may then be employed to give an indication of the current reliability of the index and a warning if the reliability of the diagnostic index becomes compromised.

Abstract: The invention relates to monitoring of pain-related responses in a patient in order to detect the level of pain experienced by the patient. At least one first measurement signal is acquired from the patient and at least one of the signals is transformed into a normalized signal having a predetermined value range. Based on the at least one normalized signal obtained in this way, a threshold condition is set and a rate at which at least one second measurement signal fulfills the threshold condition is monitored, wherein each of the at least one second measurement signal is derivable from a corresponding normalized signal and indicative of pain-related activity in the patient. The level of pain experienced by the patient depends on the rate monitored.

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 relates to the determination of the clinical state of a subject. A respective adaptive transform is applied to at least one measurement signal acquired from the subject, each adaptive transform being dependent on previously acquired history data, and a diagnostic index is formed, which is dependent on the transformed measurement signal(s) and serves as a measure of the clinical state of the subject. In order to reliably evaluate the clinical state of a subject on a fixed diagnostic scale during changes in the state of the subject, some or all of the previously acquired history data on which an adaptive transform is currently dependent is replaced with other previously acquired history data when a predetermined event is detected. The predetermined event is indicative of a change in the respective measurement signal, and the introduction of the said other previously acquired history data sets the transform ready for the change.

Abstract: The invention relates to the determination of the anesthetic state of a patient. In order to achieve a mechanism that enables establishment and maintenance of balanced anesthesia, values are established for a set of diagnostic indices. The set includes at least two diagnostic indices of which a first diagnostic index is indicative of the level of hypnosis and a second diagnostic index of the level of nociception in the patient. The combination of the at least two index values obtained is employed for indicating the anesthetic state of the patient. The combination of the at least two index values may further be employed to control the administration of drugs to the patient.

Abstract: The invention relates to the determination of the clinical stress of a subject. In order to bring about an uncomplicated and cost-effective method for monitoring the stress status of a subject, plethysmographic signal data is acquired from the subject and a first measurement signal is derived, which is indicative of a predetemined feature of the respiration modulation appearing in the said signal data. An index signal is then formed based on the first measurement signal and the index signal is employed as an index indicative of the clinical stress of the subject.

Abstract: The invention relates to the determination of the clinical state of a subject. In order to bring about an uncomplicated method for monitoring the clinical state of a subject and for accomplishing a diagnostic scale, such as a nociception scale, on which a certain reading corresponds to the same level for all patients, a normalization transform is applied to a measurement signal containing physiological data obtained from a patient, whereby a normalized measurement signal having a predetermined value range is obtained. The normalization transform is dependent on predetermined history data, such as previous signal data of said measurement signal. A diagnostic index dependent on the normalized measurement signal is then formed, the diagnostic index serving as a measure of the clinical state of the patient. The diagnostic index may be formed based on one or more normalized measurement signals.

Abstract: The invention relates to a method and arrangement for monitoring the state of the autonomous nervous system (ANS) of a patient. A first measurement signal is acquired from a patient, the first measurement signal representing a physiological signal measured from the patient. In order to enable real-time monitoring of the state of the ANS, a second measurement signal indicative of a respiration rhythm of the patient is acquired and at least one indicator signal is generated by means of the first and second measurement signals. The at least one indicator signal may then be used to obtain an indication of the state of the autonomous nervous system of the patient.

Abstract: To monitor subcortical responsiveness of a patient at least one first measurement signal is acquired from a patient and at least one second measurement signal is derived from the at least one first measurement signal. The second measurement signal is indicative of pain-related activity in the patient. A predetermined stimulus signal is then supplied to the patient and a response caused by the stimulus signal in the at least one second measurement signal is monitored in synchronization with the supplying of the stimulus signal. Based on the monitoring step, an indicator of subcortical responsiveness is determined, the indicator being indicative of the patient's level of antinociception.

Abstract: The invention relates to monitoring of pain-related responses in a patient in order to detect the level of pain experienced by the patient. At least one first measurement signal is acquired from the patient and at least one of the signals is transformed into a normalized signal having a predetermined value range. Based on the at least one normalized signal obtained in this way, a threshold condition is set and a rate at which at least one second measurement signal fulfills the threshold condition is monitored, wherein each of the at least one second measurement signal is derivable from a corresponding normalized signal and indicative of pain-related activity in the patient. The level of pain experienced by the patient depends on the rate monitored.

Abstract: The invention relates to a method of calibrating a pulse oximeter, in which the effects caused by tissue of a subject can be taken into account. A detector output signal is measured when living tissue of the subject is present between emitters and the detector in a sensor. Nominal calibration and nominal calibration characteristics are read from a memory, whereupon values for the same nominal characteristics for the sensor on living tissue of the subject are established using the detector output signal. Then, changes in the nominal calibration characteristics induced by the living tissue are calculated and a subject-specific calibration is formed by correcting the nominal calibration with the changes. Finally, the hemoglobin fractions are solved using the corrected nominal calibration.