Blood Pressure Monitoring Tool
- Created: Sunday, 01 May 2011
A computer control mouse device includes a sphygmomanometer and software package to take recordings and store them as digital data.
The MDMouse system incorporates a pre-existing medical device into a conventional computer control mouse. The tool is designed to measure blood pressure outside of the medical environment, and to provide that information for use by individuals, clinical evaluation companies (CROs), healthcare providers, and healthcare payers.
The system consists of a computer control mouse device that includes a blood pressure monitor and an application software package that resides on a PC where the blood pressure readings are displayed. The software application
for the MDMouse system displays the blood pressure readings to the user and provides a means of maintaining records and allowing the user to access past readings at any time. In addition, the software allows the user to direct his/her records to a third party, such as a physician or insurance company, or in the event of use for clinical studies, the data can go directly to the study sponsor. Other features of the system include the ability to set alarms to remind the user to take his or her blood pressure or medications, or set up doctor’s appointments.
The MDMouse system is easy to use and readily available to the patient. In today’s world, patients are in front of their computers regularly; this device makes it convenient for them to take blood pressure readings without leaving their chairs. Additionally, there is significantly greater accuracy in machine-to-machine communication, as used by the MDMouse system, as opposed to relying on patients to write down their readings and then consolidate them on a monthly basis. The blood pressure readings go directly from the MDMouse system sensor to the computer for recording on the hard drive — there is no human interaction required and none allowed. This information can be easily inserted into an Electronic Health Record (EHR) system. Once EHR systems are fully implemented in the U.S., it will be imperative that all the blood pressure monitors do what the MDMouse system already accomplishes: automatically move the data collected remotely into those EHR systems.
Inside a standard-sized computer mouse is a blood pressure finger cuff that is placed over the index finger to allow blood pressure measurement. Additional components include a pneumatic pump to inflate and deflate the cuff and a pressure sensor to identify the pulse during cuff deflation, thus allowing for measurement of blood pressure by a standard method (the “oscillometric” method). These components, and the electrical power source and processing capabilities of the computer to which the MDMouse hardware is attached, comprise a highly accurate sphygmomanometer. The PC, using the installed MDMouse software, along with the MDMouse device, will perform the calculations necessary to turn the digital data obtained by the sensor into useful information for display on the PC.
The hardware consists of the following elements: a commercially available optical mouse and an electronic sphygmomanometer. The electronic sphygmomanometer consists of a pressure cuff assembly that has the following components: inflatable air bag, a solenoid, an extender arm, a motorized air pump, a pressure sensor, and a release valve.
The solenoid and the extender arm are used to extend the cuff assembly out of the mouse housing so it can be used for taking blood pressure. The air pump provides the pressurized air to selectively expand the air bag so that it grasps the user’s finger when it is inserted into the finger cuff. The pressure sensor senses the pressure at the interface between the air bag and the finger surface. The release valve is used to release air from the air bag at a rate that is related to how the pressure sensor oscillometrically senses the systolic and diastolic blood pressure at the finger.
The blood pressure monitoring components that are situated in the mouse housing receive commands from the application software such as “start monitoring” to begin each testing session and that software also receives back the readings taken by the sensors in the mouse. That data communication is done through an MCA and USB to the UART bridge using the PC’s USB port.
The actual taking of an individual’s blood pressure using the MDMouse device proceeds as follows: The pressure of the cuff against the finger inserted into the cuff opening is initially increased until arterial vessel pulsation is beyond cutoff (total occlusion or shutdown of the artery). The cuff pressure is then slowly decreased until the first detection of arterial vessel pulsation occurs (the first pumping of the heart also commonly known as Korotkoff Phase I). The corresponding cuff pressure at this point will be substantially equal to systolic blood pressure, which is the pressure when the heart is pumping.
As cuff pressure continues to decrease, arterial vessel pulsations will eventually become undetectable through the cuff because of the lack of adequate cuff pressure to sense those pulsations (commonly known as Korotkoff Phase V). The pressure of the cuff at this point will be substantially equal to diastolic blood pressure — the pressure when the heart is at rest. The frequency of pulsations sensed between the systolic and diastolic pressures is measured and is substantially equal to the heartbeat rate or pulse rate of the individual. These two cuff pressures and the pulsation frequency are measured and captured by the MDMouse application software.