Abstract: Disclosed is an apparatus for recording respiratory rate of a subject. The apparatus comprises a first component to be arranged on the subject and away from nostrils of the subject, the first component comprises a battery, optionally electronics for the sensor, and electronics for transmitting respiration rate data; and a second component for being arranged in an area of the nose of the subject, the second component comprising at least one sensor for recording respiratory rate. Disclosed is also a method for recording respiratory rate of a subject with such an apparatus. The method comprises arranging the second component in an area of the nose of the subject; arranging the first component on the subject and no further than 30 centimeters from the second component; recording respiratory rate data with the second component, and sending the respiratory rate data to the first component; and sending the respiratory rate data from the first component to a monitor or a hub.

Abstract: A method, device, and computer program product for improving accuracy of a respiratory gas measurement from a subject ventilated at a predetermined respiration rate through a ventilator. A respiratory gas measurement value is acquired within a first expiration period of the subject, thereby to obtain a first measurement value. The ventilator is paused for a pause period within a second expiration period of the subject and a respiratory gas measurement is performed within the pause period, thereby to obtain a second measurement value. A correction factor is then determined based on the first measurement value and the second measurement value and the correction factor is employed to correct subsequent respiratory gas measurement values obtained from the subject at the predetermined respiration rate, thereby to improve the accuracy of the measurement.

Abstract: A method, device, and computer program product for improving accuracy of a respiratory gas measurement from a subject ventilated at a predetermined respiration rate through a ventilator. A respiratory gas measurement value is acquired within a first expiration period of the subject, thereby to obtain a first measurement value. The ventilator is paused for a pause period within a second expiration period of the subject and a respiratory gas measurement is performed within the pause period, thereby to obtain a second measurement value. A correction factor is then determined based on the first measurement value and the second measurement value and the correction factor is employed to correct subsequent respiratory gas measurement values obtained from the subject at the predetermined respiration rate, thereby to improve the accuracy of the measurement.

Abstract: The invention relates to a mechanism for determining the depth of sleep of a subject. In order to obtain information about the continuum of the depth of sleep in a user-friendly way without a need for high computational power, EEG signal data is obtained from a subject, REM sleep periods of the subject are detected, and a measure indicative of irregularity in the EEG signal data is derived. Based on the measure and the depicted REM sleep periods, a sleep depth index and state information are produced, where the index is indicative of the depth of sleep of the subject and the state information indicates whether or not the EEG signal data is obtained during a REM sleep period. The detection of the REM periods may be based on a bioimpedance measured from EEG electrodes simultaneously with the EEG measurement or on EOG signal data measured from the subject.

Abstract: A method and apparatus for measuring the responsiveness of a subject are disclosed. Based on physiological signal data obtained from a subject, two indices of responsiveness are determined for the subject. The first index is indicative of the responsiveness of the subject to unintentional background stimulation affecting the subject, while the second index is indicative of the responsiveness of the subject to intentional stimulation. The determination of the two indices is such that the indices are commensurable to each other, thereby to allow evaluation of the state of the subject based on the relative magnitudes of the indices.

Abstract: Method and arrangement for obtaining diagnostic information of a patient, the method comprising the steps of carrying out heart rate measurements of the patient at least during two sleep stages before the operation to obtain preoperative heart rate data, carrying out measurements containing information related to the different stages of sleep that are synchronized with the heart rate measurements to obtain preoperative sleep stage data, and calculating a dynamic heart rate variability measures by utilizing non-linear analysis from heart rate data obtained and enabling comparison of the heart rate variability measure between at least two different stages of the sleep state.

Abstract: The invention relates to a mechanism for determining the depth of sleep of a subject. In order to obtain information about the continuum of the depth of sleep in a user-friendly way without a need for high computational power, EEG signal data is obtained from a subject, REM sleep periods of the subject are detected, and a measure indicative of irregularity in the EEG signal data is derived. Based on the measure and the detected REM sleep periods, a sleep depth index and state information are produced, where the index is indicative of the depth of sleep of the subject and the state information indicates whether or not the EEG signal data is obtained during a REM sleep period. The detection of the REM periods may be based on a bioimpedance measured from EEG electrodes simultaneously with the EEG measurement or on EOG signal data measured from the subject.

Abstract: The invention relates to a method for positioning electrodes in an electrode array comprising a plurality of electrodes for central nervous system (CNS) monitoring from the forehead of a subject. In order to enable efficient detection of eye movement artifacts with a minimum number of electrodes, first and second electrodes are positioned so that eye movement in one of the horizontal or vertical directions causes a negligible overall voltage change between the first and second electrodes and at least a third electrode is positioned so that eye movement in the other of said horizontal and vertical directions causes a high potential difference between the third electrode and an auxiliary electrode, wherein the auxiliary electrode is one of the electrodes in a set comprising one of the first and second electrodes and a fourth electrode.

Abstract: The invention relates to a method and apparatus for assessing the reactivity observable in a certain physiological signal, especially the EEG signal, of a comatose subject. In order to obtain an objective and a reliable measure of the reactivity automatically and without the presence of a trained EEG specialist, a time reference corresponding to a stimulus is detected and the physiological signal data obtained from the subject is aligned with the time reference. Two sets of values are determined for a measure indicative of the amount of irregularity in the physiological signal data, both sets including at least one value of the said measure and having defined positions with respect to the time reference in time domain. Based on the two sets, the apparatus determines whether reactivity is present in the physiological signal data.

Abstract: The invention relates to a method and apparatus for measuring the responsiveness of a subject with lowered level of consciousness. Physiological signal data is obtained from the subject and a first measure indicative of the level of consciousness of the subject is derived from the physiological signal data. In order to obtain an objective measure of the responsiveness of the subject and to improve the specificity of patient monitoring, a sequence of the first measure is recorded without inducing arousals in the subject and a second measure indicative of a responsiveness of the subject is determined based on the recorded sequence. The determination of the second measure may be independent of the unintentional stimuli that cause arousals in the patient or the stimuli causing such arousals in the clinical environment may be detected to find out their effect on the first measure.

Abstract: A method concerning measurements by using an electrode array comprising three electrodes for central nervous system (CNS) monitoring from the forehead of a patient's head. A first electrode of said three electrodes is positioned between the eyebrows or immediately above the eyebrows of the patient. A third electrode of said three electrodes is positioned apart from the first electrode on the hairless fronto-lateral area of the forehead the patient. A second electrode is positioned between the first and the third electrodes on the forehead of the patient.

Abstract: The invention relates to a method and apparatus for monitoring a patient during drug administration. In the monitoring process, at least one state index indicative of the clinical state of the patient is determined based on physiological signal data obtained from the patient. In order to eliminate inconsistencies caused by varying drug combinations in the at least one state index, drug administration data is maintained, which identifies the drug(s) administered to the patient, and the determination of the at least one state index is controlled in dependence on the drug administration data, thereby to produce values for the at least one state index, which remain substantially consistent regardless of the particular combination of the drugs administered to the patient.

Abstract: The invention relates to a method and apparatus for monitoring the cerebral state of a subject. At least one of a first and second parameters is derived from the physiological signal data obtained from the subject, wherein the first parameter is indicative of the sum of spectral values of the physiological signal data in a first frequency band lying above high frequency EEG activity and the second parameter is indicative of the relative magnitudes of a first sum of k-th order spectral values and a second sum of n-th order spectral values. The second sum is calculated over a frequency band lying above high frequency EEG activity (k>2 and n>1). A state index is then formed, which is dependent on the at least one parameter and indicative of the cerebral state of the subject. The first and second parameters may be used in the Bispectral Index (BIS™) algorithm.

Abstract: A method concerning measurements by using an electrode array comprising three electrodes for central nervous system (CNS) monitoring from the forehead of a patient's head. A first electrode of said three electrodes is positioned between the eyebrows or immediately above the eyebrows of the patient. A third electrode of said three electrodes is positioned apart from the first electrode on the hairless fronto-lateral area of the forehead the patient. A second electrode is positioned between the first and the third electrodes on the forehead of the patient.

Abstract: Method of positioning electrodes in an electrode array, comprising at least five or at least seven electrodes for central nervous system (CNS) monitoring from the forehead of a patient's head. The electrodes of the array are optimally located for discriminating EEG, FEMG and EM components from the recorded biopotential signals.

Abstract: A method and apparatus for ascertaining the cerebral state of a patient using generalized spectral entropy of the EEG signal.

Abstract: Method of positioning electrodes in an electrode array, comprising at least five or at least seven electrodes for central nervous system (CNS) monitoring from the forehead of a patient's head. The electrodes of the array are optimally located for discriminating EEG, FEMG and EM components from the recorded biopotential signals.

Abstract: A method concerning measurements by using an electrode array comprising three electrodes for central nervous system (CNS) monitoring from the forehead of a patient's head. A first electrode of said three electrodes is positioned between the eyebrows or immediately above the eyebrows of the patient. A third electrode of said three electrodes is positioned apart from the first electrode on the hairless fronto-lateral area of the forehead the patient. A second electrode is positioned between the first and the third electrodes on the forehead of the patient.

Abstract: A closed loop method and apparatus for controlling the administration of an hypnotic drug to a patient. Electroencephalographic (EEG) signal data is obtained from the patient. At least one measure of the complexity of the EEG signal data is derived from the data. The complexity measure may comprise the entropy of the EEG signal data. The EEG signal data complexity measure is used as the feedback signal in a control loop for an anesthetic delivery unit to control hypnotic drug administration to the patient in a manner that provides the desired hypnotic level in the patient. An EEG signal complexity measure obtained from the cerebral activity of the patient can be advantageously used in conjunction with a measure of patient electromyographic (EMG) activity to improve the response time of hypnotic level determination and of the feedback control of drug administration. A pharmacological transfer function may be used, along with pharmacokinetic and pharmacodynamic models.

Abstract: A closed loop method and apparatus for controlling the administration of an hypnotic drug to a patient. Electroencephalographic (EEG) signal data is obtained from the patient. At least one measure of the complexity of the EEG signal data is derived from the data. The complexity measure may comprise the entropy of the EEG signal data. The EEG signal data complexity measure is used as the feedback signal in a control loop for an anesthetic delivery unit to control hypnotic drug administration to the patient in a manner that provides the desired hypnotic level in the patient. An EEG signal complexity measure obtained from the cerebral activity of the patient can be advantageously used in conjunction with a measure of patient electromyographic (EMG) activity to improve the response time of hypnotic level determination and of the feedback control of drug administration. A pharmacological transfer function may be used, along with pharmacokinetic and pharmacodynamic models.