Patent Description:
Clinicians are often unable to determine whether an alarm is triggered due to patient deterioration, or due to noise artifacts such as from patient motion. This can lead to confusion regarding the need to respond to the alarm, and can result in alarm fatigue.

<CIT>discloses an alarm actuating circuit associated with an automatic blood pressure recorder is triggered when a patient's systolic or diastolic pressure does not fall within a prescribed range. The recorder is associated with a pneumatic regulator including a constant-volume reference chamber and associated pressure-sensitive inflation and deflation valves to effect a precise linear depressurization of an inflatable cuff which has been applied to the patient and pressurized to a value higher than the patient's systolic pressure. Pulses obtained from an ultrasonic or other suitable detector sensitive to movements of the patient's arterial wall in synchronism with the blood flow surges as the cuff is depressurized below the patient's systolic pressure are integrated and then translated into variable-duration marking impulses. Such impulses are successively applied to the actuating input of a pen or other marker associated with an X-Y recording chart, the pen being linearly scanned along one chart axis at the constant depressurization rate of the cuff. During such scan, the pen records, on the chart, a linear pattern of marks each of which has a length corresponding to the duration of the marking impulse then applied to its actuating input.

<CIT> discloses an apparatus for measuring both the systolic and diastolic blood pressure of an individual. A pressurable cuff having an additional tightening band for advantageously positioning a cuff and microphone on an artery is described. The microphone is connected to first the second filters having respective passbands for analyzing the frequency content for recovered pulse signals. The apparatus provides for automatic pressurizing and depressurizing of the cuff whereby the artery is occluded and opened to permit passage of the blood flow. The pressure at the time of receipt of signals from the filters is measured as the systolic pressure. The diastolic blood pressure is measured with apparatus in accordance with the invention by monitoring signals from one of the filters.

In general terms, the present disclosure relates to monitoring physiological variables for alarm management. Various aspects are described in this disclosure, which include, but are not limited to, the following aspects.

In one aspect, a method of continuous patient monitoring comprises: initiating an interval mode for measuring blood pressure, the interval mode including measuring the blood pressure at predetermined intervals over a predetermined period of time; taking a first blood pressure measurement at one of the predetermined intervals; determining whether the first blood pressure measurement is abnormal; when the first blood pressure measurement is abnormal, taking a second blood pressure measurement after a predetermined delay; comparing the first and second blood pressure measurements to confirm whether the blood pressure is normal or abnormal; and when the blood pressure is confirmed as abnormal, transmitting the blood pressure to an alarm management application.

In another aspect, a patient monitoring device comprises: at least one processing device; and a memory device storing instructions which, when executed by the at least one processing device, cause the device to: initiate an interval mode for measuring blood pressure at predetermined intervals over a predetermined period of time; take a first blood pressure measurement at one of the predetermined intervals; determine whether the first blood pressure measurement is abnormal; when the first blood pressure measurement is abnormal, take a second blood pressure measurement after a predetermined delay; compare the first and second blood pressure measurements to confirm whether the blood pressure is normal or abnormal; and when the blood pressure is confirmed as abnormal, transmitting the blood pressure to an alarm management application.

In another aspect, a method of patient monitoring for alarm management comprises: inflating a cuff to have a partial pressure around a limb of a patient that is less than a pressure applied to the limb when measuring blood pressure; monitoring an internal pressure inside the cuff; determining motion artifacts from changes in the internal pressure; and transmitting the motion artifacts to delay an alarm triggered by an abnormal measurement received from a physiological sensor attached to the limb.

In another aspect, a patient monitoring device comprises: at least one processing device; and a memory device storing instructions which, when executed by the at least one processing device, cause the device to: inflate a cuff to have a partial pressure around a limb of a patient that is less than a pressure applied to the limb when measuring blood pressure; monitor an internal pressure inside the cuff; determine motion artifacts from changes in the internal pressure; and transmit the motion artifacts to delay an alarm triggered by an abnormal measurement received from a physiological sensor attached to the limb.

In another aspect, a method of patient monitoring for alarm management comprises: receiving electrocardiogram signals from an electrode attached a body; processing the electrocardiogram signals to determine motion artifacts, including calculating motion values that correspond to a strength of the motion artifacts; assigning a location to the motion values based on a location of the electrode on the body; checking for sensors in the location of the motion values, the sensors being used for measuring physiological variables; calculating motion weighted values for physiological measurements obtained from the sensors based on the motion values; and transmitting the motion weighted values to an alarm delay algorithm.

In another aspect, a patient monitoring device comprises: at least one processing device; and a memory device storing instructions which, when executed by the at least one processing device, cause the device to: receive electrocardiogram signals from an electrode attached a body; process the electrocardiogram signals to determine motion values; assign a location to the motion values; check for sensors in the location of the motion values, the sensors being used for measuring physiological variables; calculate motion weighted values for physiological measurements obtained from the sensors based on the motion values; and transmit the motion weighted values to an alarm delay algorithm.

In another aspect, a patient monitoring device comprises: at least one processing device; and a memory device storing instructions which, when executed by the at least one processing device, cause the at least one processing device to: initiate an interval mode that includes measuring blood pressure at predetermined intervals over a predetermined period of time; take a first blood pressure measurement at one of the predetermined intervals; determine whether the first blood pressure measurement is abnormal; take a second blood pressure measurement after a predetermined delay when the first blood pressure measurement is determined abnormal; compare the first and second blood pressure measurements to confirm whether the first blood pressure measurement is abnormal; and trigger an alarm when the first blood pressure measurement is confirmed as abnormal.

In another aspect, a patient monitoring device comprises: at least one processing device; and a memory device storing instructions which, when executed by the at least one processing device, cause the at least one processing device to: inflate a cuff around a limb of a patient to have a partial pressure less than a pressure applied by the cuff to the limb when measuring blood pressure; monitor an internal pressure inside the cuff; identify motion artifacts based on changes in the internal pressure; and delay an alarm triggered by a physiological sensor based on the motion artifacts.

In another aspect, a patient monitoring device comprises: at least one processing device; and a memory device storing instructions which, when executed by the at least one processing device, cause the at least one processing device to: receive electrocardiogram signals from an electrode attached to a body; identify motion artifacts from the electrocardiogram signals; assign a location to the motion artifacts based on where the electrode is attached to the body; identify sensors taking physiological measurements in the location assigned to the motion artifact; calculate motion weighted values based on the motion artifacts for the physiological measurements taken by the sensors; and use the motion weighted values in an alarm delay algorithm.

<FIG> illustrates an example of a system <NUM> for monitoring physiological variables of a patient P in a clinical environment such as a hospital. The monitored physiological variables include heart rate, respiration rate, ECG, blood oxygen saturation (SpO2), end tidal carbon dioxide (etCO2), and the like. The system <NUM> includes sensors connected to a monitoring device <NUM> for monitoring the physiological variables. Examples of the sensors include an electrocardiogram (ECG) sensor <NUM>, a pressure sensor <NUM>, and a SpO2 sensor <NUM>. The system <NUM> can also include a contact-free sensor <NUM> and an etCO2 sensor <NUM>, which are shown in <FIG>.

As will be described in more detail below, physiological sensing and motion detection functions are combined in one or more of the sensors in the system <NUM>. For example, the pressure sensor <NUM> can be used to both determine non-invasive blood pressure measurements and detect motion artifacts that can affect or influence the physiological sensing performed by the other sensors in the system <NUM>. In addition, or as an alternative, the ECG sensor <NUM> can be used to both measure electrocardiogram signals and detect motion artifacts that can affect or influence the physiological sensing performed by the other sensors in the system <NUM>.

The system <NUM> includes a cuff <NUM>, which is shown placed around an upper arm of the patient P. The cuff <NUM> is comfortable to wear such that it can be worn by the patient P for a prolonged duration of time such as during twenty-four-hour blood pressure monitoring. The cuff <NUM> is connected to a cuff controller <NUM> and a pressure sensor <NUM>, and the cuff controller <NUM> and the pressure sensor <NUM> are both connected to the monitoring device <NUM>.

In some examples, the cuff <NUM>, cuff controller <NUM>, pressure sensor <NUM> are integrated into a single device such as a blood pressure monitor or sphygmomanometer. In some examples, the blood pressure monitor or sphygmomanometer is a separate device that connects to the monitoring device <NUM>. Alternatively, the blood pressure monitor or sphygmomanometer can be integrated with the monitoring device <NUM> as a single machine.

The cuff controller <NUM> is used to inflate the cuff <NUM> until blood flow under the cuff <NUM> is occluded, and then slowly releases the cuff <NUM> in a controlled manner to gradually allow blood flow under the cuff <NUM>. The cuff controller <NUM> can include a pump or similar device to inflate the cuff <NUM>. For example, the cuff controller <NUM> can inflate the cuff <NUM> with air to increase the pressure of the cuff <NUM> around the upper arm of the patient P. The cuff controller <NUM> can control the amount of pressure applied by cuff <NUM> around the upper arm of the patient P.

The pressure sensor <NUM> is used as a non-invasive blood pressure sensor. The pressure sensor <NUM> detects a first signal from partially occluded blood vessels under the cuff <NUM>, while the pressure of the cuff <NUM> is slowly released in a controlled manner by the cuff controller <NUM>. The first signal is generated from blood flowing through the partially occluded blood vessels. The pressure sensor <NUM> can sample the first signal multiple times at various intervals.

The pressure sensor <NUM> detects a second signal from pressure changes inside the cuff <NUM> when the cuff is at least partially inflated. The pressure sensor <NUM> is located within or about the cuff <NUM> to detect the pressure change inside the cuff. When the cuff <NUM> is partially inflated, the pressure sensor <NUM> can detect pressure changes inside the cuff that can result from the patient P shifting their body weight such as when moving from a supine position to a side position or a sitting upright position while resting in bed. Thus, the pressure sensor <NUM> is also used as a motion sensor to detect motion which can affect the readings of the other physiological variables. This can eliminate the need for a dedicated motion sensor such as an accelerometer attached to the patient P, or piezoelectric sensors, load cells, or combinations thereof that detect movements of the patient P while the patient is supported on a bed or similar support structure.

The pressure sensor <NUM> sends the first and second signals to the monitoring device <NUM>, which processes the first and second signals to generate outputs. For example, the monitoring device <NUM> can process the first signal to non-invasively estimate systolic and diastolic blood pressure of the patient P. Also, the monitoring device <NUM> can process the second signal to detect motion artifacts that can affect or influence the physiological data acquired by the monitoring device <NUM> from the other sensors in the system <NUM>, such as the physiological variables monitored by the ECG sensor <NUM>, SpO2 sensor <NUM>, contact-free sensor <NUM>, and EtC2 sensor <NUM>.

Thus, the second signal acquired from the pressure sensor <NUM> can be combined with the data acquired from the other sensors in the system <NUM> to determine whether an irregular physiological variable reading is caused by motion artifact. For example, when motion artifacts detected from the pressure sensor <NUM> suggest a movement of the patient P that can cause interference with the electrocardiogram readings from the ECG sensor <NUM>, the monitoring device <NUM> can instruct the ECG sensor <NUM> to cancel or retake the electrocardiogram readings, or flag the electrocardiogram readings as likely having an error due to the movement.

As shown in <FIG>, the ECG sensor <NUM> includes a plurality of electrodes <NUM> attached to the body of the patient P. For example, the electrodes <NUM> can be attached to various locations on the chest, right arm, left arm, right leg, left leg, and head of the patient P.

The electrodes <NUM> are connected to the ECG sensor <NUM> by leads <NUM>. The ECG sensor <NUM> can be a <NUM>/<NUM>-lead or <NUM>-lead ECG machine. The signals acquired from the electrodes <NUM> are used by the ECG sensor <NUM> for monitoring the electrical activity of the patient P's heart, such as by generating an electrocardiogram that can be displayed on a display device and/or printed.

The ECG sensor <NUM> also communicates the signals to the monitoring device <NUM> as raw data that can be used to detect motion artifacts that can affect or influence physiological data acquired from the other sensors in the system <NUM>. The signals from the ECG sensor <NUM> can be analyzed to determine the location of the motion artifacts. For example, the signals can be sorted based on the location of the electrodes such that the signals can be used to detect motion artifacts on the right arm, left arm, right leg, left leg, and the like. Thus, the ECG sensor <NUM> can be used as a motion sensor. This can eliminate the need for a dedicated motion sensor such as an accelerometer attached to the patient P, or piezoelectric sensors, load cells, or combinations thereof that detect movements of the patient while supported on a bed or similar structure.

The motion artifacts detected from the signals acquired from the ECG sensor <NUM> are used by the monitoring device <NUM> to improve the physiological data acquired from the other sensors in the system <NUM>. For example, when the signal from the ECG sensor <NUM> detects patient motion that can interfere with a blood pressure measurement from the pressure sensor <NUM>, the monitoring device <NUM> can cancel or retake the blood pressure measurement, or flag the blood pressure measurement as likely having an error due to the motion. Thus, the signal acquired from the ECG sensor <NUM> can be combined with physiological data from the other sensors in the system <NUM> to determine whether an irregular physiological variable reading is caused by motion.

As further shown in <FIG>, the SpO2 sensor <NUM> is a clip that is attached to a finger of the patient P. Alternatively, the SpO2 sensor <NUM> can attach to other body parts of the patient P such as the patient's earlobe. The SpO2 sensor <NUM> is connected to the monitoring device <NUM>, and sends data to the monitoring device <NUM> to estimate the blood oxygen saturation of the patient P.

As shown in <FIG>, the monitoring device <NUM> communicates with a server <NUM> via a communications network <NUM>. The server <NUM> operates to manage the patient P's medical history and information. The server <NUM> can be operated by a healthcare service provider, such as a hospital or medical clinic. The monitoring device <NUM> sends physiological data acquired from the sensors in the system <NUM> to the server <NUM> via the connection to the communications network <NUM>. In at least some examples, the server <NUM> is a cloud server or similar type of server.

The server <NUM> can include an electronic medical record (EMR) system <NUM> (alternatively termed electronic health record (EHR)). Advantageously, the server <NUM> can store the physiological data acquired from the sensors in the system <NUM> in an electronic medical record (EMR) <NUM> or electronic health record of the patient P located in the EMR system <NUM> via the connection with the monitoring device <NUM> over the communications network <NUM>.

The communications network <NUM> communicates data between one or more devices, such as between the monitoring device <NUM> and the server <NUM>. The communications network <NUM> may also be used to communicate data between the one or more sensors and devices in the system <NUM> such as between the ECG sensor <NUM>, cuff controller <NUM>, pressure sensor <NUM>, and SpO2 sensor <NUM>, and also the contact-free sensor <NUM> and etCO2 sensor <NUM>, which are shown in <FIG>.

The communications network <NUM> can include any type of wired or wireless connections, or any combinations thereof. Examples of wireless connections include cellular network connections such as <NUM> or <NUM>. The wireless connections can also be accomplished using Wi-Fi, ultra-wideband (UWB), Bluetooth, radio frequency identification (RFID), and the like.

<FIG> schematically illustrates another example of the system <NUM>, which includes the monitoring device <NUM> and sensors for monitoring physiological variables of the patient. In this example, in addition to the ECG sensor <NUM>, pressure sensor <NUM>, and SpO2 sensor <NUM>, a contact-free sensor <NUM> and an etCO2 sensor <NUM> are also connected to the monitoring device <NUM>.

The contact-free sensor <NUM> is a sensor that can continuously monitor physiological variables of the patient without physically contacting the patient. For example, the contact-free sensor <NUM> can be positioned on a bed frame below a mattress on which the patient rests in the clinician environment. The contact-free sensor <NUM> can be used to measure physiological variables such as heart rate and respiration rate of the patient. An example of the contact-free sensor <NUM> is described in <CIT>.

The etCO2 sensor <NUM> is a sensor that measures the level of carbon dioxide that is released at the end of an exhaled breath, called end-tidal carbon dioxide (etCO2). The etCO2 sensor <NUM> can also be used to measure the respiration rate of the patient. The etCO2 sensor <NUM> can be attached to a breathing tube, a face mask, or similar breathing devices.

As shown in <FIG>, the monitoring device <NUM> includes a computing device <NUM> with at least one processing device <NUM> and a memory device <NUM>. The at least one processing device <NUM> is an example of a processing unit such as a central processing unit (CPU). In some examples, the at least one processing device <NUM> can include one or more digital signal processors, field-programmable gate arrays, or other electronic circuits.

The memory device <NUM> operates to store data and instructions for execution by the at least one processing device <NUM>, including an interval measurement application <NUM>, a motion detection application <NUM>, and an alarm management application <NUM>, described in more detail below. The memory device <NUM> includes computer-readable media, which may include any media that can be accessed by the monitoring device <NUM>. By way of example, computer-readable media include computer readable storage media and computer readable communication media.

Computer readable storage media includes volatile and nonvolatile, removable and non-removable media implemented in any device configured to store information such as computer readable instructions, data structures, program modules, or other data. Computer readable storage media can include, but is not limited to, random access memory, read only memory, electrically erasable programmable read only memory, flash memory, and other memory technology, including any medium that can be used to store information that can be accessed by the monitoring device <NUM>. The computer readable storage media is non-transitory.

Computer readable communication media embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term "modulated data signal" refers to a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, computer readable communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, radio frequency, infrared, and other wireless media. Combinations of any of the above are within the scope of computer readable media.

The interval measurement application <NUM> is used by the monitoring device <NUM> to perform an interval mode for measuring physiological variables. For example, the cuff controller <NUM>, pressure sensor <NUM>, and monitoring device <NUM> can operate under the interval mode where blood pressure readings are taken at predetermined intervals over a predetermined period of time. The cuff <NUM> is continuously worn by the patient P, and the interval measurement application <NUM> instructs the cuff controller <NUM> to inflate the cuff <NUM> at each interval, while using the pressure sensor <NUM> to non-invasively estimate systolic and diastolic blood pressure of the patient P when the pressure of the cuff <NUM> is slowly released in a controlled manner by the cuff controller <NUM>. As an illustrative example, the interval mode can occur over a <NUM> hour period of time, and each interval can occur every <NUM> or <NUM> minutes during the <NUM> hour period.

The motion detection application <NUM> detects patient motion using one or more of the sensors connected to the monitoring device <NUM>. The motion detection application <NUM> can detect patient motion using the cuff <NUM>, cuff controller <NUM>, and pressure sensor <NUM>. For example, the motion detection application <NUM> can instruct the cuff controller <NUM> to inflate the cuff <NUM> to maintain a partial pressure around a limb (e.g., arm) of the patient P. The partial pressure is a pressure that allows patient motion to be detected from internal pressure changes inside the cuff <NUM> that can result from the patient P shifting their body weight while resting on a surface such as a bed. The pressure changes inside the cuff <NUM> are detected by the pressure sensor <NUM>.

The partial pressure is less than the pressure that is applied to the patient P's arm when measuring the blood pressure of the patient P. Additionally, the partial pressure is less than the safe venous return pressure (SVRP), which is a standard for patient safety that specifies a pressure limit at which reasonable venous return can take place to prevent excessive blood pooling. For adults, the SVRP is 15mmHg. For neonates, the SVRP is <NUM> mmHg.

In one example, the cuff <NUM> is inflated to maintain the partial pressure between the intervals in the interval mode. In another example, the cuff <NUM> is inflated to maintain the partial pressure for a continuous period of time when the monitoring device <NUM> is not operating under the interval mode. In another example, the cuff <NUM> is inflated to maintain the partial pressure when an abnormal reading is received from one of the other sensors connected to the monitoring device <NUM>, during continuous monitoring physiological variables including heart rate, respiration rate, blood oxygen saturation (SpO2), end tidal carbon dioxide (etCO2), and the like.

The motion detection application <NUM> can detect patient motion using the signals from the ECG sensor <NUM>. For example, the motion detection application <NUM> can instruct the at least one processing device <NUM> to analyze the signals received by the ECG sensor <NUM> using one or more filters to detect motion. Examples of the one or more filters for filtering the signals from the ECG sensor <NUM> can include band-pass, band-stop, high-pass, and low-pass filters.

The alarm management application <NUM> can automatically cancel, delay, and/or reset one or more alarms that are triggered (e.g., due to one or more physiological variables being above upper alarm limits or below lower alarm limits) when patient motion is detected from the motion detection application <NUM>. Advantageously, the alarm management application <NUM> can eliminate the need for a clinician to manually cancel, delay, and/or reset the alarms.

The alarm management application <NUM> can also provide a selectable time delay for alarm events (e.g., when an abnormal blood pressure measurement is received in the interval mode) that a clinician can adjust. For example, a default time delay can be set at two minutes after an alarm is triggered, and a clinician can adjust the time delay to have a <NUM> minute delay via a user interface displayed on a display device <NUM> of the monitoring device <NUM>. The time delay allows a clinician to finish a task in another room when the alarm is not a threat to the patient.

The monitoring device <NUM> further includes a sensor interface <NUM> that operates to communicate with the various sensors of the system <NUM>. The sensor interface <NUM> can include both wired interfaces and wireless interfaces. The ECG sensor <NUM>, pressure sensor <NUM>, SpO2 sensor <NUM>, contact-free sensor <NUM>, and etCO2 sensor <NUM> can wirelessly connect to the sensor interface <NUM> through Wi-Fi, ultra-wideband (UWB), Bluetooth, and similar types of wireless connections. Alternatively, or in addition to wireless connectivity, the ECG sensor <NUM>, pressure sensor <NUM>, SpO2 sensor <NUM>, contact-free sensor <NUM>, and etCO2 sensor <NUM> can also connect to the monitoring device <NUM> using wired connections that plug into the sensor interface <NUM>.

As shown in <FIG>, the monitoring device <NUM> includes the display device <NUM>, which operates to display one or more user interfaces. In some examples, the display device <NUM> is a touchscreen such that the user interfaces operate to receive inputs from a clinician. In such examples, the display device <NUM> operates as both a display device and a user input device. The monitoring device <NUM> can also support physical buttons on a housing of the device that operate to receive inputs from the clinician to control operation of the monitor device and enter data.

The monitoring device <NUM> can also include an audio unit <NUM>. The audio unit <NUM> generates audio sounds such as to sound an alarm when an alarm is triggered by the alarm management application <NUM>. Also, the audio unit <NUM> can be used to provide instructions.

<FIG> illustrates an example of a method <NUM> of continuous patient monitoring. The method <NUM> can be performed by the interval measurement application <NUM> using the cuff <NUM>, cuff controller <NUM>, and pressure sensor <NUM> to retake non-invasive blood pressure measurements during the interval mode when an abnormal blood pressure measurement is detected.

The method <NUM> overcomes obstacles in the interval mode where the cuff <NUM> stays on the patient's arm over a predetermined period of time (e.g., <NUM> hours), and the blood pressure measurements are automatically triggered at predetermined intervals (e.g., every <NUM> or <NUM> minutes). In the interval mode, blood pressure measurements are typically reported without a clinician being present such that a clinician is unable to rerun the blood pressure measurement or perform a manual blood pressure reading to confirm whether an abnormal blood pressure measurement is true or accurate. This can lead to inaccurate blood pressure measurements being recorded by the monitoring device <NUM> and stored in the EMR <NUM> of the patient. Additionally, this can trigger false alarms and can lead to alarm fatigue.

An abnormal blood pressure measurement is above an upper alarm limit or below a lower alarm limit. The upper and lower alarm limits are based on normal or default values. A normal resting blood pressure for human adults is approximately <NUM>/<NUM> mmHg, a high blood pressure for human adults is considered to be <NUM>/<NUM> mmHg or higher, and a low blood pressure for human adults is considered to be <NUM>/<NUM> mmHg or lower. Thus, an abnormal blood pressure measurement is above <NUM>/<NUM> mmHg or below <NUM>/<NUM> mmHg. Additionally, an abnormal blood pressure measurement is when no blood pressure measurement is obtained due to technical error.

The method <NUM> includes an operation <NUM> of initiating the interval mode for measuring blood pressure. In the interval mode, the cuff <NUM> stays on the patient's arm over a predetermined period of time (e.g., <NUM> hours), and the blood pressure measurements are automatically triggered at predetermined intervals (e.g., every <NUM> or <NUM> minutes).

Next, the method <NUM> includes an operation <NUM> of taking a blood pressure measurement in accordance with the interval mode. The blood pressure measurement taken at operation <NUM> is referred to herein as a first blood pressure measurement. The blood pressure measurement is taken by using the cuff controller <NUM> to inflate the cuff <NUM> until blood flow under the cuff <NUM> is occluded, and then slowly releasing the cuff <NUM> in a controlled manner to gradually allow blood flow under the cuff <NUM> while using the pressure sensor <NUM> to detect a signal from the partially occluded blood vessels under the cuff <NUM> for non-invasively estimating systolic and diastolic blood pressure. The blood pressure measurement is automatically measured at operation <NUM> without assistance from the patient, a clinician, or other personnel around the patient.

Next, the method <NUM> includes an operation <NUM> of determining whether the blood pressure measurement obtained from operation <NUM> is abnormal (i.e., is outside of an upper or lower alarm limit, or not obtained due to technical error). When the blood pressure measurement is not abnormal such that it is within a normal range (i.e., "No" at operation <NUM>), the method <NUM> proceeds to an operation <NUM> of transmitting the blood pressure measurement.

When the blood pressure measurement obtained from operation <NUM> is outside the upper and lower alarm limits or no blood pressure measurement is obtained due to technical error such that the blood pressure measurement is abnormal (i.e., "Yes" at operation <NUM>), the method <NUM> proceeds to an operation <NUM> of retaking the blood pressure measurement. The blood pressure measurement retaken at operation <NUM> is referred to herein in some instances as a second blood pressure measurement or as a third blood pressure measurement.

Operation <NUM> is performed after a predetermined delay, which is an amount of time after the blood pressure measurement initially taken in operation <NUM>. For example, the blood pressure is retaken at operation <NUM> at least <NUM> seconds after the blood pressure is initially taken at operation <NUM>. This avoids prolonged periods in which the cuff <NUM> is continuously inflated or repeatedly inflated, which can affect blood circulation and cause blood pooling. The predetermined amount of time between operations <NUM>, <NUM> can be based on a regulatory standard for a long term automatic mode of measuring blood pressure.

Next, the method <NUM> proceeds to operation <NUM> of comparing the second blood pressure measurement retaken at operation <NUM> to the first blood pressure measurement taken at operation <NUM> to confirm whether the blood pressure of the patient is normal or abnormal. In some examples, confirmation at operation <NUM> is based on whether the first and second blood pressure measurements are both abnormal. In other examples, confirmation at operation <NUM> is based on whether the second blood pressure measurement matches the first blood pressure measurement or is within a predefined threshold of the first blood pressure measurement.

When the blood pressure is confirmed as abnormal (i.e., "Yes" at operation <NUM>), the method <NUM> proceeds to the operation <NUM> of performing an action based on the confirmed abnormal blood pressure measurement. Operation <NUM> can include triggering an alarm during the interval mode such as by communicating the confirmed abnormal blood pressure measurement to the alarm management application <NUM>. Additionally, or alternatively, operation <NUM> can include storing the blood pressure in the EMR <NUM> via the communications network <NUM>.

In examples when the blood pressure is confirmed as normal (i.e., "No" at operation <NUM>), the method <NUM> includes storing the second blood pressure measurement retaken at operation <NUM> in the EMR <NUM> via the communications network <NUM>.

In some examples, when the blood pressure is not confirmed as abnormal (i.e., "No" at operation <NUM>), the method <NUM> proceeds to operation <NUM> of determining whether a delay limit is reached. The delay limit is based on an allowed delay for the interval blood pressure measurements. The delay limit can be a default value or can be value set by a clinician based on the condition of the patient. For example, when the patient is healthy, the delay limit can allow for a longer delay because there is less urgency to receive the blood pressure measurement. However, when the patient is in a deteriorated state such as due to sepsis, the delay limit is shorter because there is greater urgency to receive the blood pressure measurement.

When the delay limit is not reached (i.e., "No" at operation <NUM>), the method <NUM> can optionally proceed to operation <NUM> of providing an instruction to the patient. As an illustrative example, the abnormal blood pressure measurement can be due to patient motion which either causes the blood pressure measurement to be incorrect, or causes there to be no blood pressure measurement due to technical error. In some instances, the method <NUM> can include receiving data indicating that the patient is moving from another sensor in the system <NUM> such as the ECG sensor <NUM>. In such examples, the instruction provided in operation <NUM> can be for the patient to remain still or stop moving to retake the blood pressure measurement without motion artifacts.

In some examples, the instruction provided in operation <NUM> is an audio message that is played back by the audio unit <NUM> of the monitoring device <NUM>. Alternatively, or in addition to the audio message, the instruction provided in operation <NUM> can be a message displayed on the display device <NUM>, or can be a blinking light understood by the patient as an instruction to remain still while their blood pressure is being retaken by the blood pressure monitor.

Next, the method <NUM> repeats the operation <NUM> of retaking the blood pressure measurement. Operation <NUM> is performed after the predetermined delay (e.g., <NUM> seconds) has passed from when the blood pressure measurement was previously retaken in operation <NUM>.

The method <NUM> repeats the operation <NUM>, this time comparing the third blood pressure measurements retaken at operation <NUM> to the first blood pressure measurement taken at operation <NUM> to confirm whether the blood pressure is normal or abnormal. When the blood pressure is confirmed as abnormal (i.e., "Yes" at operation <NUM>), the method <NUM> proceeds to operation <NUM> of transmitting a confirmed blood pressure measurement which can include the first blood pressure measurement, or the second blood pressure measure, or the third blood pressure measurement, or an average of the first, second, and third blood pressure measurements.

In some examples, when the blood pressure is confirmed as normal (i.e., "No" at operation <NUM>), the method <NUM> includes transmitting the third blood pressure measurement retaken at operation <NUM> to the server <NUM> via the communications network <NUM> for storage in the EMR <NUM>. Alternatively, when the blood pressure is not confirmed (i.e., "No" at operation <NUM>), the method proceeds again to operation <NUM> of determining whether the delay limit is reached.

When the delay limit is reached (i.e., "Yes" at operation <NUM>), the method <NUM> proceeds to operation <NUM> which can include determining an average value of the blood pressure measurement taken at operation <NUM> and the blood pressure measurement(s) retaken at operation <NUM>. Alternatively, or additionally, operation <NUM> can include determining a majority value (i.e., a blood pressure measurement that appears most often, i.e., a mode value) between the blood pressure measurement taken at operation <NUM> and the blood pressure measurement(s) retaken at operation <NUM>. Operation <NUM> can include sending at least one of the average value and the majority value of the blood pressure measurements taken in operations <NUM>, <NUM>.

At operation <NUM>, the method <NUM> can include sending the blood pressure measurement to the server <NUM> for storage in the EMR <NUM> of the patient located in the EMR system <NUM>. Additionally, the alarm management application <NUM> can acquire the blood pressure measurement sent at operation <NUM> to trigger an alarm when the measurement is abnormal. Advantageously, the method <NUM> can reduce false alarms while the monitoring device <NUM> operates under the interval mode for measuring blood pressure.

<FIG> illustrates another example of a method <NUM> of continuous patient monitoring. The method <NUM> is performed to detect patient motion during continuous physiological variable monitoring. The method <NUM> can be performed by the motion detection application <NUM> installed on the monitoring device <NUM> using the cuff <NUM>, cuff controller <NUM>, and pressure sensor <NUM>.

The method <NUM> can be performed to detect patient motion during an interval mode for measuring physiological variables performed by the interval measurement application <NUM>. In some instances, the method <NUM> is performed to detect patient motion between measurement intervals for systolic and diastolic blood pressure. Thus, the method <NUM> can be performed to monitor for patient motion whenever the cuff <NUM> is not being used to measure patient blood pressure. In the method <NUM>, the cuff <NUM> can be used as a continuous motion sensor.

The patient motion can affect or influence the signals received by the monitoring device <NUM> from the other physiological sensors in the system <NUM>, causing erroneous readings. Additionally, the patient motion can naturally cause some of the physiological variables to change such as heart rate and respiration rate. Advantageously, the patient motion detected in accordance with the method <NUM> can be used by the alarm management application <NUM> installed on the monitoring device <NUM> to cancel, delay, or reset an alarm triggered by an abnormal reading received by one of the other sensors connected to the monitoring device <NUM>.

The method <NUM> includes an operation <NUM> of checking a status of the cuff <NUM> to determine whether the cuff <NUM> is being used to measure blood pressure or not. For example, the cuff <NUM> can be used during the interval mode to measure blood pressure at predetermined intervals (e.g., <NUM> mins) over a predetermined period of time (e.g., <NUM> hours). When the cuff <NUM> is being used to measure blood pressure, (i.e., "Yes" at operation <NUM>) the method <NUM> returns to operation <NUM> of checking a status for a blood pressure measurement. When the blood pressure measurement is not in progress (i.e., "No" at operation <NUM>) the method <NUM> proceeds to operation <NUM> of instructing the cuff controller <NUM> to partially inflate the cuff <NUM>.

At operation <NUM>, the motion detection application <NUM> instructs the cuff controller <NUM> to inflate the cuff <NUM> to have a partial pressure that is sufficient for the pressure sensor <NUM> (which is located within or about the cuff <NUM>) to detect internal pressure changes inside the cuff <NUM>. The partial pressure allows the pressure sensor <NUM> to detect internal pressure changes inside the cuff <NUM> that can result from patient motion such as when the patient shifts their body weight when supported on a surface as a bed to move from a supine position to a sitting upright position.

At operation <NUM>, the motion detection application <NUM> instructs the cuff controller <NUM> to inflate the cuff <NUM> to have the partial pressure, which is less than the pressure applied to the patient's arm when estimating the blood pressure of the patient. Also, the partial pressure is less than the SVRP (e.g., less than 15mmHg for adults, and less than <NUM> mmHg for neonates).

Next, the method <NUM> proceeds to operation <NUM> of monitoring an internal pressure inside the cuff <NUM> to determine whether there are any pressure changes inside the cuff <NUM>. As described above, pressure changes inside the cuff <NUM> may result of the patient shifting their body weight while supported on a surface such as a bed, and can be used to detect patient motion.

When no pressure change is detected (i.e., "No" at operation <NUM>), the method <NUM> returns to operation <NUM> and continues monitoring the internal pressure inside the cuff <NUM>. When a pressure change is detected (i.e., "Yes" at operation <NUM>), the method <NUM> proceeds to operation <NUM> of processing the pressure change inside the cuff <NUM> to determine a motion artifact.

Operation <NUM> includes processing raw data obtained from the pressure sensor <NUM> to determine a motion artifact. In some examples, the raw data is processed to calculate a motion value that quantifies a strength or intensity of the motion artifact. The processing at operation <NUM> can also include normalizing the motion value to be on a common scale.

The processing of the raw data in operation <NUM> can also include assigning a location to the motion artifact. For example, the motion artifact can be assigned the location of the arm on which the cuff <NUM> is attached. The location of the motion artifact can be used by the alarm management application <NUM> to determine an affect or influence on physiological variables measured by other sensors in the same location, such at the blood oxygen saturation measured from the SpO2 sensor <NUM> when attached to the same arm as the cuff <NUM>.

Next, the method <NUM> proceeds to operation <NUM> of communicating the motion artifact and assigned location to the alarm management application <NUM>. The motion artifact can be used as an input for an algorithm performed by the alarm management application <NUM> to cancel, delay, and/or reset one or more alarms triggered by an abnormal reading from another sensor in the system <NUM>. Additionally, the motion artifact can be used to determine a dynamic ranking of redundant physiological variables, which will be described in more detail below.

Also, the motion artifact can be used by the monitoring device <NUM> to improve blood pressure measurements taken during the interval mode. For example, when the motion artifact is detected within a predetermine amount of time (e.g., <NUM> seconds) before a scheduled blood pressure measurement in accordance with the interval mode, the monitoring device <NUM> can issue a warning or an instruction for the patient to remain still before the schedule measurement.

<FIG> illustrates another example of a method <NUM> of continuous patient monitoring. The method <NUM> can be performed by the motion detection application <NUM> installed on the monitoring device <NUM> using the cuff <NUM>, cuff controller <NUM>, and pressure sensor <NUM>. The method <NUM> includes many of the operations included in the method <NUM>.

The method <NUM> differs from the method <NUM> in that the method <NUM> includes an operation <NUM> of receiving an abnormal reading from another sensor in the system <NUM> that triggers the method <NUM> perform operations <NUM>-<NUM> using the cuff <NUM>, cuff controller <NUM>, and pressure sensor <NUM> to detect patient motion. This information can be used by the alarm management application <NUM> to cancel, delay, and/or reset one or more alarms triggered by the abnormal reading. Thus, the method <NUM> is performed when an abnormal reading is received from another sensor in the system <NUM> such that the cuff <NUM> is used as an event driven motion sensor. This is different from the method <NUM> which is performed to continuously monitor for patient motion whenever the cuff <NUM> is not being used to measure patient blood pressure.

As an illustrative example, operation <NUM> can include receiving an abnormal SpO2 reading from the SpO2 sensor <NUM> attached to the same arm of the patient as the cuff <NUM> (see <FIG>). When the abnormal SpO2 reading is received, the method <NUM> performs operations <NUM>-<NUM> using the cuff <NUM>, cuff controller <NUM>, and pressure sensor <NUM> to determine whether there are patient motion artifacts on the arm of the patient where the SpO2 sensor <NUM> is attached. Thus, the method <NUM> is performed to verify whether an abnormal reading from the SpO2 sensor <NUM> is due to patient motion or not, and this information is used by the alarm management application <NUM> to cancel, delay, and/or reset one or more alarms triggered by the abnormal SpO2 reading.

After receiving the abnormal reading in operation <NUM>, the method <NUM> includes an operation <NUM> of instructing the cuff controller <NUM> to partially inflate the cuff <NUM> (see description of operation <NUM> in the method <NUM>); an operation <NUM> of monitoring the pressure inside the cuff <NUM> (see description of operation <NUM> in the method <NUM>); an operation <NUM> of determining whether a pressure change is detected inside the cuff <NUM> (see description of operation <NUM> in the method <NUM>); an operation <NUM> of determining a motion value (see description of operation <NUM> in the method <NUM>); and an operation <NUM> of communicating the motion artifact to the alarm management application <NUM> (see description of operation <NUM> in the method <NUM>).

Like in the method <NUM>, the motion artifact communicated in operation <NUM> can be used as an input for an algorithm performed by the alarm management application <NUM>. Also, the motion artifact communicated in operation <NUM> can be used to determine a dynamic ranking of redundant physiological variables, which will be described in more detail below.

<FIG> illustrates another example of a method <NUM> of continuous patient monitoring. The method <NUM> is performed by the motion detection application <NUM> installed on the monitoring device <NUM> using the ECG sensor <NUM>. The method <NUM> is performed to detect patient motion from raw ECG signals acquired from the electrodes <NUM> of the ECG sensor <NUM>.

During continuous patient monitoring, physiological sensors are easily affected by patient motion artifacts. For example, each sensor in the system <NUM> can be affected individually or in combination with other sensors in the system <NUM> based on the strength and location of the patient motion artifact. As will be described in more detail, the method <NUM> analyzes the raw ECG signals from the ECG sensor <NUM> to determine the strength and location of patient motion artifacts, which can be used by the alarm management application <NUM> to cancel, delay, and/or reset one or more alarms triggered during continuous physiological variable monitoring.

Referring now to <FIG>, the method <NUM> includes an operation <NUM> of receiving raw ECG signals from the ECG sensor <NUM>. As described above, the raw ECG signals are detected by the electrodes <NUM> attached to the body of the patient, and are communicated to the ECG sensor <NUM> via the leads <NUM>. The ECG sensor <NUM> can then send the raw ECG signals to the monitoring device <NUM>. In alternative examples, the monitoring device <NUM> can receive the raw ECG signals directly from the electrodes <NUM> when the leads <NUM> are directly connected to the monitoring device <NUM>.

Next, the method <NUM> includes an operation <NUM> of processing the raw ECG signals to determine a motion artifact. The motion artifact is determined from signal noise in the raw ECG signals. The signal noise can be filtered to improve detection of motion artifacts. For example, low frequency noise is used to identify motion artifacts, while high frequency noise is excluded.

In some examples, the processing performed at operation <NUM> can include calculating a motion value that corresponds to a strength or magnitude of the motion artifact. Operation <NUM> can further include normalizing the motion value to be on a scale that corresponds with motion values obtained from other sensors in the system <NUM>, such as from the pressure sensor <NUM>.

Next, the method <NUM> includes an operation <NUM> of determining a location of the motion artifact. While <FIG> shows operation <NUM> occurring after completion of operation <NUM>, in alternative examples operation <NUM> can occur before operation <NUM>. Also, in some instances, operations <NUM>, <NUM> may occur substantially at the same time such that they are simultaneous.

As described above, the ECG sensor <NUM> includes electrodes <NUM> attached to different locations on the body of the patient P such as the chest, right arm, left arm, right leg, left leg, and head (see <FIG>). The location of the motion artifact is determined based on the location of the electrode <NUM> that detects the raw ECG signal. For example, motion artifacts detected from an electrode <NUM> connected to the right arm of the patient are mapped to a right arm location, motion artifacts detected from an electrode <NUM> connected to the left arm of the patient are mapped to a left arm location, motion artifacts detected from an electrode <NUM> connected to the right leg of the patient are mapped to a right leg location, motion artifacts detected from an electrode <NUM> connected to the left leg of the patient are mapped to a left leg location, and so on.

Additionally, raw ECG signals from a plurality of the electrodes <NUM> can be combined to determine a direction of the motion artifacts. For example, a right arm to left leg direction can be determined by processing the raw ECG signals from electrodes <NUM> attached to the right arm and left leg of the patient. Similarly, a right arm to left arm direction can be determined by processing the raw ECG signals from electrodes <NUM> attached to the right arm and left arm of the patient. Additional examples are possible. Thus, in some examples, motion values calculated from the raw ECG signal are vectors that indicate a direction of patient motion.

Next, the method <NUM> proceeds to an operation <NUM> of communicating the motion artifact and its location to the alarm management application <NUM>. The motion artifact communicated in operation <NUM> can be used as an input for an algorithm performed by the alarm management application <NUM>. Also, the motion artifact communicated in operation <NUM> can be used to determine a dynamic ranking of redundant physiological variables.

<FIG> illustrates an example of a method <NUM> of managing alarms performed by the alarm management application <NUM> when installed on the monitoring device <NUM>. The method <NUM> can be performed to delay an alarm when patient motion is detected.

The method <NUM> includes an operation <NUM> of receiving motion artifacts from the sensors in the system <NUM>. As described above, the motion artifacts are determined from raw data acquired from the sensors in the system <NUM> such as the pressure sensor <NUM> or ECG sensor <NUM> that are used to measure physiological variables (e.g., blood pressure, electrocardiogram readings), such that the sensors are used as both physiological and motion sensors. This can eliminate the need for a dedicated motion sensor, and thus reduce the number of sensors in the system <NUM>.

In some examples, the method <NUM> includes an operation <NUM> of pre-processing the raw motion artifacts from each sensor to determine motion values. As an illustrative example, operation <NUM> can include performing the following algorithm: <MAT> where motion_r is a motion value, and r is a raw motion artifact collected from a sensor. Thus, the motion values can be calculated independent of the sensor source such as the pressure sensor <NUM> or ECG sensor <NUM>. When processing the raw motion artifacts from the ECG sensor <NUM>, the motion values can be calculated as vectors to indicate a direction of motion. A location can be assigned to each motion value such as to indicate whether it is from the right or left arm.

In other examples, the method <NUM> receives pre-processed motion values in operation <NUM> such that operation <NUM> does not need to be performed in the method <NUM>. Instead, the motion artifacts are already pre-processed such as by performance of operation <NUM> in the method <NUM>, operation <NUM> in the method <NUM>, and/or operation <NUM> in the method <NUM>.

Next, the method <NUM> can include an operation <NUM> of determining whether the motion value exceeds a predetermined threshold. Operation <NUM> is performed so that only motion values strong enough to affect or influence the readings from another sensor in the system <NUM> are considered for adjusting an alarm setting. When the motion value does not exceed the predetermined threshold (i.e., "No" at operation <NUM>), the motion value can be ignored, and the method <NUM> returns to operation <NUM> and continues to receive motion artifacts.

When the motion value exceeds the predetermined threshold (i.e., "Yes" at operation <NUM>), the method <NUM> proceeds to operation <NUM> of checking for sensors that measures physiological variables in the same location where the motion value is detected. When no other sensor is in the same location of the determined motion value (i.e., "No" at operation <NUM>), the method <NUM> returns to operation <NUM> and continues receiving motion artifacts.

When at least one other physiological sensor is determined to be in the same location of the detected motion value (i.e., "Yes" at operation <NUM>), the method <NUM> proceeds to an operation <NUM> of calculating motion weighted values for physiological measurements that are received from a sensor that is in the same location. For example, when a motion value is detected on the left arm of the patient P due to signal noise from a raw ECG signal acquired from an electrode <NUM> attached to the left arm of the patient P, operation <NUM> determines whether there are any additional physiological sensors attached to the left arm of the patient P.

In the example shown in <FIG>, the cuff <NUM> and pressure sensor <NUM> (which are used to measure the systolic and diastolic blood pressure of the patient P) are also attached to the left arm of the patient P. Also, the SpO2 sensor <NUM> (which is used to measure the blood oxygen saturation of the patient P) is also attached to the left arm of the patient P.

The motion weighted values are calculated from the motion values, and are used by an alarm delay algorithm is performed to delay an alarm when abnormal physiological measurements are detected. For example, when an abnormal SpO2 measurement is detected, the alarm delay algorithm delays triggering an alarm for a predetermined period of time (e.g., <NUM> seconds) to determine whether the SpO2 measurement returns to the normal range. As another example, the alarm delay algorithm can determine how much the abnormal SpO2 measurement is outside of the normal range, and for how long, to determine whether to trigger an alarm.

The motion weighted value influences the effect that an abnormal physiological measurement has on the decision by the alarm delay algorithm to trigger an alarm. For example, when an abnormal physiological measurement is received when a high motion value is detected, the abnormal physiological measurement is assigned a low motion weighted value. Thus, the abnormal physiological measurement will have a small influence or will be ignored by the alarm delay algorithm when determining when to trigger an alarm.

The motion weighted values that are used by the alarm delay algorithm are calculated in accordance with the following algorithm: <MAT> where motion_r is the motion value, and m is a multiplier. The multiplier m is defined per pairing of sensor and physiological variable alarm. For example, the multiplier m can be assigned a value of <NUM> for motion values detected from the pressure sensor <NUM> for use by a SpO2 alarm. As another example, the multiplier m can be assigned a value of <NUM> for motion values detected from the ECG sensor <NUM> for use by a SpO2 alarm.

The normalizeQ function can use any normalization algorithms (e.g., min-max, standard score). Also, depending on the distribution of the weight_m, other types of transformations can be applied, such as log transformations.

In view of the foregoing, a larger motion value (motion_r) leads to a smaller motion weighted value (weight_m) such that an abnormal physiological measurement will have a minor influence or will be ignored for determining when to trigger an alarm. A smaller motion value (motion_r) will lead to a larger motion weighted value (weight_m) for abnormal physiological measurements that are detected when there is little or no patient motion. The motion weighted values (weight_m) are then used by the alarm delay algorithm, which can be performed by the alarm management application <NUM> to determine when to trigger or delay an alarm.

<FIG> illustrates an example of a method <NUM> of dynamic ranking of redundant physiological sensors performed by the monitoring device <NUM>. The method <NUM> is performed for physiological variables that are captured by multiple sensors in the system <NUM>. The method <NUM> assigns sensor confidence levels that are based on motion artifacts detected in accordance with any of the methods described above. The sensor confidence levels can be used to adjust a redundant sensor ranking to reduce inaccurate measurements used for alarm decisions. Thus, the method <NUM> can be used to reduce false alarms, and thereby reduce alarm fatigue.

The method <NUM> includes an operation <NUM> of receiving motion artifacts from the sensors in the system <NUM>. As described above, the motion artifacts are determined from raw data acquired from the sensors in the system <NUM> (e.g., pressure sensor <NUM>, ECG sensor <NUM>) that are used to measure physiological variables (e.g., blood pressure, electrocardiogram readings), such that the sensors are used as both physiological and motion sensors. This can eliminate the need for a dedicated motion sensor, and thus reduce the number of sensors used by the system <NUM>.

Next, the method <NUM> proceeds to operation <NUM> of checking for sensors that measure physiological variables in the same location of the determined motion artifact. When no other sensor is in the same location of the determined motion value (i.e., "No" at operation <NUM>), the method <NUM> returns to operation <NUM> and continues receiving motion artifacts.

When at least one other physiological sensor is determined to be in the same location of the detected motion value (i.e., "Yes" at operation <NUM>), the method <NUM> proceeds to an operation <NUM> of adjusting confidence levels of one or more physiological variables that are measured by sensors in the same location as the determined motion artifact.

Referring back to <FIG> and <FIG>, there are multiple sensors that can measure physiological variables redundantly. For example, heart rate can be determined from data acquired from the ECG sensor <NUM>, SpO2 sensor <NUM>, or contact-free sensor <NUM>. Thus, there are at least three sets of redundant heart rate measurements: a first set determined from data acquired from the ECG sensor <NUM>, a second set determined from data acquired from the SpO2 sensor <NUM>, and a third set determined from data acquired from the contact-free sensor <NUM>.

As another example, the respiration rate of the patient P can be determined from data acquired from the etO2 sensor <NUM> and from data acquired the contact-free sensor <NUM>. Thus, there are two sets of redundant respiration rate measurements: a first set determined from the etO2 sensor <NUM> data, and a second set determined from the contact-free sensor <NUM> data.

In some examples, each sensor has a default confidence level such that certain sensors are preferred over others for measuring certain physiological variables, when there are redundant sensors that can measure the same physiological variable. For example, the ECG sensor <NUM> may be preferred for measuring the heart rate over other sensors such as the SpO2 sensor <NUM>, which can also be used to measure heart. Alternatively, in some instances, the SpO2 sensor <NUM> may be preferred for measuring the heart rate over other sensors such as the ECG sensor <NUM>.

In operation <NUM>, the method <NUM> lowers the confidence level for sensors that measure physiological variables in the same location as the determined motion artifact. As an illustrative example, when a motion artifact is determined to be on the left arm of the patient (e.g., from raw ECG signals that are collected from an electrode <NUM> attached to the left arm of the patient), and the SpO2 sensor <NUM> is also attached to the left arm of the patient (see <FIG>), the data acquired from the SpO2 sensor <NUM> is given a lower confidence level because of potential influence by the detected motion artifact, such that it may be inaccurate and cause a false alarm.

Next, the method <NUM> includes an operation <NUM> of updating a redundant sensor ranking for physiological variables captured by multiple sensors. In example described above where the heart rate measurements from the SpO2 sensor <NUM> are given a lower confidence level because the SpO2 sensor <NUM> is located where a motion artifact is detected, the SpO2 sensor <NUM> is given a lower ranking than the other sensors that can be used to measure heart rate that are not affected by the motion artifact such as the ECG sensor <NUM> which uses an electrode attached to the chest of the patient P to measure heart rate, or the contact-free sensor <NUM> which can continuously monitor the heart rate without physically contacting the patient.

The redundant sensor ranking can be used to select certain sensors over other sensors to measure the physiological variables. For example, the monitoring device <NUM> can select the ECG sensor <NUM> or the contact-free sensor <NUM> to measure the heart rate of the patient over the SpO2 sensor <NUM> because the ECG sensor <NUM> and the contact-free sensor <NUM> each have a higher ranking than the SpO2 sensor <NUM>, based on the location of the motion artifact.

<FIG> illustrates an example of redundant physiological variables displayed on the display device <NUM> of the monitoring device <NUM>. In this example, heart rate measurements from the SpO2 sensor <NUM> have a larger variance than the heart rate measurements from the ECG sensor <NUM>. This can result from motion artifacts having a stronger influence on the date acquired from the SpO2 sensor <NUM>, than on the data acquired from the ECG sensor <NUM>. Thus, in this example, the heart rate measurements from the SpO2 sensor <NUM> are assigned a lower confidence level than the heart rate measurements from the ECG sensor <NUM>. As a result, the ECG sensor <NUM> can be assigned a higher redundant sensor ranking than the SpO2 sensor <NUM>, such that the ECG sensor <NUM> is selected over the SpO2 sensor <NUM> for measuring heart rate.

Claim 1:
A patient monitoring device (<NUM>), comprising:
at least one processing device (<NUM>); and
a memory device (<NUM>) storing instructions which, when executed by the at least one processing device (<NUM>), cause the at least one processing device (<NUM>) to:
initiate an interval mode (<NUM>) that includes measuring blood pressure at predetermined intervals over a predetermined period of time;
take a first blood pressure measurement (<NUM>) at one of the predetermined intervals;
determine whether the first blood pressure measurement is abnormal (<NUM>);
take a second blood pressure measurement (<NUM>) after a predetermined delay when the first blood pressure measurement is determined abnormal;
compare the first blood pressure measurement to the second blood pressure measurement (<NUM>) wherein if the second blood pressure measurement is within a predefined threshold of the first blood pressure measurement, the first blood pressure measurement is confirmed as abnormal; and
trigger an alarm (<NUM>) when the first blood pressure measurement is confirmed as abnormal.