Abstract: A method and system for eliminating artifacts in an oscillation envelope are disclosed. The method and system comprise evaluating conformance of the oscillometric envelope blood pressure data with a predetermined expected pattern and excluding one or more data points of the oscillometric envelope blood pressure data based on non-conformance with the expected pattern. The expected pattern is based upon generally known physiological principles relating to oscillometric envelopes, a curve fit representing an oscillometric envelope from a previous determination, or other types of criteria.

Abstract: A technique for comparing pressure oscillations obtained during a blood pressure determination wherein two or more sets of matching criteria may be employed. The set of matching criteria to be employed is determined based on the heart rate variability or the presence of heart beat irregularities or arrhythmias as determined by an independent heart monitor, such as an ECG. The selected set of matching criteria may then be employed in determining the acceptability of the time interval between two oscillations and the equivalence of the two oscillations based upon one or more oscillation characteristics, such as peak amplitude. In this manner, non-consecutive oscillations may be matched and used in determining blood pressure.

Abstract: A method and system for determining pulse rate of a patient are disclosed. The method and system include acquiring measured information for at least one pulse at a pressure step, determining and storing quality values for the at least one pulse at the pressure step, analyzing pulse matching criteria for the pressure step, and determining pulse rate based on the measured information, quality values, and pulse matching criteria.

Abstract: A method and system for making pulse rate and blood pressure determinations is disclosed. The method and system comprise collecting oscillometric blood pressure data from pulses, determining individual quality values for feature measurements of the pulses, obtaining an overall quality assessment based on the individual quality values, repeating the collecting step until overall quality level is satisfied, and determining blood pressure and pulse rate using the individual quality values.

Abstract: A method and system for determining when to make a reversion to smaller cuff pressure steps during an oscillometric blood pressure measurement is disclosed. The method and system comprise comparing conformance of oscillometric envelope blood pressure data with previous blood pressure data, including measuring a shift between the oscillometric envelope blood pressure data and an oscillometric envelope derived from the previous blood pressure data. In addition, the method and system include making a reversion decision based on whether the shift exceeds an allowable threshold. Once a reversion decision is made a subsequent decision may be made as to the need for increasing the cuff pressure level.

Abstract: A method and system for eliminating artifacts in an oscillation envelope are disclosed. The method and system comprise evaluating conformance of the oscillometric envelope blood pressure data with a predetermined expected pattern and excluding one or more data points of the oscillometric envelope blood pressure data based on non-conformance with the expected pattern. The expected pattern is based upon generally known physiological principles relating to oscillometric envelopes, a curve fit representing an oscillometric envelope from a previous determination, or other types of criteria.

Abstract: A physiological-signal-analysis device for determining a blood pressure value of a patient and a method of operating the device. The device includes a cuff attachable to an extremity of the patient, a pneumatic system connected to the cuff that supplies a fluid to the cuff, a pressure transducer that measures the pressure signal having pressure oscillations, and a control unit connected to the pneumatic system and the pressure transducer. The control unit is operable to acquire a first oscillation having a first fiducial point, acquire a second oscillation having a second fiducial point, calculate a time interval representing a time from the first fiducial point to the second fiducial point, decide against selecting the second oscillation when the time interval is not a substantial integral multiple of a nominal oscillation period, and calculate a blood pressure value based on selected oscillations.

Abstract: Blood pressure is measured using the pulse transit time required for the blood volume pulse to propagate between two locations in an animal. Impedance plethysmography is employed to detect when the blood volume pulse occurs at one location. The plethysmograph may detect thoracic impedance to determine when the aortic heart valve opens or it may detect impedance at one location on a limb of the animal. Occurrence of the blood volume pulse at another location can be determined by impedance plethysmography or another technique, such as pulse oximetry. The calculation of cardiac stroke volume can be employed to compensate the derivation of the blood pressure for effects due to blood vessel compliance. A nonblood pressure monitor may periodically provide a reference blood pressure measurement that is used calibrate derivation of the blood pressure based on the pulse transit time.

Abstract: Blood pressure is measured using the pulse transit time required for the blood volume pulse to propagate between two locations in an animal. Impedance plethysmography is employed to detect when the blood volume pulse occurs at one location. The plethysmograph may detect thoracic impedance to determine when the aortic heart valve opens or it may detect impedance at one location on a limb of the animal. Occurrence of the blood volume pulse at another location can be determined by impedance plethysmography or another technique, such as pulse oximetry. The calculation of cardiac stroke volume can be employed to compensate the derivation of the blood pressure for effects due to blood vessel compliance. A nonblood pressure monitor may periodically provide a reference blood pressure measurement that is used calibrate derivation of the blood pressure based on the pulse transit time.

Abstract: A patient monitor has a plurality of voice alarm messages stored in a memory. When the monitor detects an occurrence of an alarm condition, such as an usual physiological characteristic of the patient, a voice alarm message associated with that condition is played back through a loudspeaker. To enable the patient monitor to be used throughout the world, the end user is able to replace each of the prerecorded voice alarm messages. Thus the end user is able to store voice messages in the native language and dialect spoken where the monitor is used.

Abstract: A physiological-signal-analysis device for determining a blood pressure value of a patient and a method of operating the device. The device includes a cuff attachable to an extremity of the patient, a pneumatic system connected to the cuff that supplies a fluid to the cuff, a pressure transducer that measures the pressure signal having pressure oscillations, and a control unit connected to the pneumatic system and the pressure transducer. The control unit is operable to acquire a first oscillation having a first fiducial point, acquire a second oscillation having a second fiducial point, calculate a time interval representing a time from the first fiducial point to the second fiducial point, decide against selecting the second oscillation when the time interval is not a substantial integral multiple of a nominal oscillation period, and calculate a blood pressure value based on selected oscillations.

Abstract: An automated sphygmomanometer which utilizes quality algorithms to stop any further analysis at various points during a blood pressure determination because of corrupted data. If the data is so corrupted that giving blood pressure numbers is inappropriate, this is recognized and the determination stopped. The quality algorithms make a decision to get more data with the hope of improving the blood pressure estimation. The request for data occurs both before and/or after a curve fitting process, if such a process is utilized. Some information is also provided to the cuff pressure control function about which pressure levels would be best for gathering the additional data. The quality algorithms are also used to make a decision as to whether it is appropriate to publish the blood pressure values obtained. Control parameters (weights) may be set within the blood pressure algorithm to help with other aspects of the NIBP algorithm and improve the quality of the final published numbers.

Abstract: A reconfigurable user interface for a modular patient monitor which selectively populates menus for operator selection based on the parameters which are available at any given time. Due to event processing, when a parameter module is added or removed from the system, the reconfigurable user interface is updated immediately to reflect the addition or subtraction of the associated parameter. A flash box in each menu provides shortcuts to the most likely menu option in response to asynchronous events such as alarms and the like. The flash box also assists the operator with the particular steps that must be followed to properly setup or operate a particular feature of the system. Since the menus are not modal, an operator may navigate the menus without making any selections or changing the state of the device.

Abstract: An automated sphygmomanometer which triggers a blood pressure determination upon detection of a significant change in the patient's heart rate variability (HRV). The HRV can be measured directly from the NIBP signal or, when a multiparameter monitor is used, the HRV can be measured from the ECG signal or the NIBP signal. HRV is continuously monitored and the baseline HRV is correlated with baseline blood pressure values. Changes in HRV are displayed continuously on a display so that the clinician can determine whether to initiate an NIBP measurement or, on the other hand, the NIBP measurement can be triggered automatically in response to a change in HRV without any intervention by the clinician. Alternatively, the patient monitor can "learn" the correlation between HRV and blood pressure changes and only alert the clinician when a significant change in HRV has taken place.

Abstract: An automated non-invasive blood pressure (NIBP) monitor having a stat mode of operation wherein several cycles of blood pressure measurement are undertaken in rapid succession by inflating a cuff on an appendage of the patient in order to quickly provide a clinician with readings of blood pressure and pulse rate. The NIBP monitor adaptively determines a minimum wait time between stat mode blood pressure measurement cycles by recognizing that the minimum wait time is proportional to the area under the pressure-time curve of the previous inflation/deflation measurement cycle. The calculated area is divided by a clinical constant derived from sampled patient data to determine the minimum wait time. The minimum wait time between blood measurement cycles so determined allows for venous return of blood that has accumulated in a patient's extremity and minimizes the discomfort experienced by the patient while maximizing the amount of collected data.

Abstract: A data playback device which records, stores, and plays back actual patient oscillometric blood pressure data to create a more realistic NIBP simulation for testing of an NIBP monitor. The system is made up of two units, a computer and a converter. The converter has a Universal Asynchronous Receiver/Transmitter (UART) connected to the computer and 16-bit D/A and A/D converters connected to the input and output, respectively, of a blood pressure monitor. The A/D converter senses cuff pressure and sends the signal to the computer. The computer then calculates the pressure pulse data from the stored patient data and sends it to the monitor via the D/A converter, where the pressure pulse data is converted to a voltage and electronically summed with the pressure transducer signal output by the blood pressure monitor under test.

Abstract: A method of measuring blood pressure where a plurality of oscillometric data values are measured from a subject at a plurality pressure levels, a function curve having the shape of an oscillometric envelope is selected and computational model fit to the data, using the Gauss-Marquardt method of model fitting. Once the curve is model fit, blood pressure is measured using the oscillometric method. Included in the step of model fitting is the step of computing the parameter of the function curve that minimizes the error between the function curve and the data values at the respective pressure levels thereby approximating the oscillometric envelope based upon data values.

Abstract: An automated sphygmo-manometer which digitizes the pressure transducer output with sufficient resolution to preserve the details of the measured oscillation complexes. The "composite" arterial pulse signal containing the DC pressure component and the oscillation complexes is processed in a single processing channel so that the amplitudes of the oscillation pulse can be measured in the presence of the static components. Any necessary filtering is performed in the digital domain using known digital signal processing (DSP) techniques. In addition, dither signals may be added to the arterial pulse signal in the single processing channel in order to increase the apparent resolution. A simple finite impulse response (FIR) filter is used to sum respective samples to form high resolution samples from a plurality of low resolution samples.

Abstract: An automated sphygmomanometer which automatically determines when a blood pressure determination needs to be made. During a "guard mode" determination, a cuff on an appendage of the patient is frequently inflated to a check pressure, which is preferably below the patient's mean arterial pressure ("MAP"), and the signature (shape, amplitude, pulse period, etc.) of the measured oscillometric signal is compared to a stored signature of a portion of an oscillometric signal at a corresponding portion of the oscillometric envelope determined during a previous blood pressure determination. If these signals differ by some predetermined amount, it is determined that the patient's blood pressure has changed significantly and that a new blood pressure determination needs to be conducted immediately. These guard mode determinations are made in addition to the normal blood pressure determinations made at predetermined intervals typically selected by the user.

Abstract: An automated sphygmomanometer in which the so-called "air effect" (a slow rise or fall in cuff pressure caused by step inflates or deflates) is substantially eliminated by deflating (inflating) the pressure cuff to a pressure lower (higher) than the target pressure, waiting a short time interval, and then inflating (deflating) the pressure cuff to the target pressure. The driving force that causes the air effect to settle out after a step inflate or deflate is proportional to the size of the step change in pressure and is thus greatest during the wait time before the pressure cuff is inflated or deflated to the target pressure. Once at the target pressure, the remaining air effect is counteracted by the incremental air effect introduced by the latter inflate or deflate so that the air effect cancels out.