Abstract: The present invention provides a system and method for establishing a synchronized time frame for signals in a medical monitoring system. In particular, the present invention provides a system and method for synchronizing the time frame of stimulation signals provided by a stimulator to a subject and response signals received by an amplifier device from the subject in response thereto. Thus, the present invention allows accurate display and analysis of the relationship between stimulation and response signals by a monitoring device. Time frame synchronization of stimulus and response signals is achieved using a periodic bus cycle clock signal which is provided by a bus, i.e., an IEEE 1394 bus, connecting together each of the devices in the monitoring system.

Abstract: The present invention provides a medical signal monitoring system and method for displaying physiological signals of different types and modalities in different formats on a single system. Physiological signals, e.g., electrical physiological signals from electrodes attached to a subject, are provided to the system. The raw wide band physiological signals may be recorded on disk, and may be processed multiple times to display desired signals of interest. The parameters used to process the signals to be displayed are selectable by an operator employing a user interface. The user interface allows an operator to define a set of panels in which one or more signals will be displayed. The type of panel selected to display the signal determines the basic format of the signal to be displayed, e.g., various types of waveforms. A signal to be displayed in a panel is defined by selecting, for example, the signals from two electrodes attached to a subject from which a montaged pair signal to be displayed is derived.

Abstract: In order to detect the intra-cranial pressure in the skull of a test subject it is proposed to attach to the skull at least two electrodes in such a way that they have an electrical contact with the skull. Via a measuring device, the time curve of an electrical resistance and/or of a capacitance between the two electrodes is obtained as an electrical signal (p(t)). An extreme value of the electrical signal, following a blood pressure maximum according to a systole with a substantially uniform delay, is determined as a first amplitude value. A second amplitude value is obtained from the electrical signal (p(t)). This value is accepted at a point where the electrical signal has for the first time after the first amplitude value either a maximum or a turning point. A third amplitude value is obtained from the electrical signal after the second amplitude value. A standardized pressure measurement value is obtained from the amplitude values for further utilization.

Abstract: An electric reflex hammer is provided which produces consistent triggering signals at the moment of impact of the hammer against a patient. A sealed switch, rigidly attached to the hammer near the striking surface of the hammer, and a switch activator, used to make the switch closure, provide the triggering signal. Use of the sealed switch allows the switch contacts to move freely without the tension or weight effects of connection wires attached to the contacts. Instead, fixed terminals extending from the sealed switch are provided, whereby the hammer may be attached by a wire to an electrical measuring device. Consistent switch closure and triggering signals are achieved, therefore, regardless of how the connection wire is attached to the hammer, or how the switch is activated. This improvement in consistency allows for much more accurate measurement of muscle response time using electronic measurement of physiological signals, such as through use of an evoked potential recording device.

Abstract: The effect of noise in the displayed information obtained from transcranial Doppler measurements is reduced by estimating the spectra of the returned Doppler signal as the average of Fourier spectra computed using multiple windows for the data being analyzed. The windows are chosen so that the spectra from different windows are approximately statistically independent, thereby reducing the variance of the spectrum by the averaging process. The Doppler data may be obtained by applying repeated pulses of ultrasonic energy to the head of a subject and isolating the Doppler frequency components of the return signal to obtain a set of data from a selected number of pulses. The data set so obtained has the multiple window functions applied thereto to obtain multiple windowed data sets which are operated on, as in a digital signal processor, to obtain multiple discrete Fourier transforms of the windowed data sets.