Creating Accurate Blood Pressure Sensors for Medical Equipment

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In the medical industry, blood pressure monitoring is essential. Readings are used to evaluate general health and diagnose diseases. High blood pressure, otherwise known as hypertension, is a serious health risk and can also be indicative of other health problems.1

Thus, accurate and reliable blood pressure monitoring data is essential to ensure positive health outcomes for patients. Blood pressure monitoring is not only necessary for standard use but is critical when it comes to monitoring a patient’s condition online during critical surgical operations.

Extracorporeal membrane oxygenation (ECMO) is a crucial medical application that necessitates precise online monitoring. ECMO is used throughout certain surgical procedures where the patient’s heart and lung functions are compromised or for critically ill patients.

In an ECMO machine, blood is pumped outside the body for carbon dioxide removal and reoxygenation before returning it to the patient.2  ECMO is a feasible substitute for mechanical ventilation as it is able to reduce lung damage invoked by the positive pressure used in these methods.

Blood pressure monitoring equipment is essential when it comes to monitoring a patient’s condition and the ECMO machine itself.3 A typical healthy blood pressure level is traditionally lower than 120/80 mmHg. However, low blood pressure can be seen to fall as low as 90/60 mmHg.

In applications such as ECMO, blood pressure monitors with an extended reading range can be highly beneficial.

ECMO Machine featuring the BP Series extended range pressure sensor.

Merit Sensor Systems

Merit Sensor Systems is a globally renowned, industry-leading company with experience designing and producing highly accurate, piezoresistive technology-based pressure sensors. The company provides pressure sensors for blood pressure monitoring applications and a range of medical equipment.

The patient’s blood pressure measurements can be significantly impacted by the resting environment. One way in which data quality can be improved is by ambulatory blood pressure testing, in which portable devices are used to record blood pressure measurements throughout the day.4

MEMS piezoresistive sensors and assemblies, such as the BP Series, are ideally suited for portable blood pressure monitoring applications due to their compact sensor footprints.

Merit Sensor has a variety of sensors available for blood pressure monitoring applications. These include the BP Series, which operates in normal pressure ranges, and an extended range version suited for applications such as ECMO, where measurements must be taken over a wide range of -500 – 1000 mmHg.

The BP + T is designed for ultra-compact applications which additionally measure temperature ranges.

BP Series Sensors

Blood pressure monitoring sensors from Merit Sensor are ideal for invasive blood pressure monitoring applications and measurements, such as ECMO.

The standard BP Series configuration BP0001 covers the pressure range of -30 to 300 mmHg, providing a reliable signal that does not need any temperature correction (operating temperature 15-40 °C).

An ultra-compact sensor with an extremely robust design, the sensor is suitable for burst pressure readings up to 800 psi. Additionally, it is compliant with AAMI BP22 and RoHS standards.

Sensors provided by Merit Sensor Systems can be easily integrated into a range of medical devices, with standard solder pads providing connectivity. The standard seal diameter is 4.8 mm (BP0001), and a smaller seal diameter of 3.2 mm (BP0002), which minimizes the device’s overall footprint.

The small seal diameter in the sensors lowers the amount of blood in contact with the sensor, minimizing the risk of clotting or coagulation, which can decrease overall blood flow and cause problems with readings.

Alongside the sensor, a media-compatible medical dielectric gel is utilized for medical applications. The BP Series also includes an IMDS file for rapid and easy media compatibility verification, minimizing the time required to develop device prototypes.

       

BP Series 4.8mm Standard Seal Diameter               BP Series 3.2mm Small Seal Diameter

Extended Range

The BP Series Extended configuration provides measurements in the range of -500-1000 mmHg and can be used in applications such as ECMO. The system operates at a broader pressure range than the standard configuration.

The blood pressure monitoring sensors from Merit Sensor Systems are designed to handle high-pressure conditions and provide accurate readings over their entire operational range.

With an extended product shelf life of up to three years, the solutions offered by Merit Sensor Systems extend the lifespan of medical devices and ensure that pressure monitors remain functional, whether they are used as short-term or long-term solutions.

BP Series Extended Pressure Range Statistics

The graph below shows the over-pressure specifications limits for the BP Series Extended between -500 to 1000 mmHg. The test results are available in the Overpressure/Accuracy Report.

The BP + T sensor, which integrates pressure and temperature measurements in one device, is available as an upgrade option. The BP + T sensor is a direct in-flow measurement sensor that can monitor pressure and temperature at a single location.

The temperature reading is directly proportional to the Ohmic reading of the embedded thermistor, which is coated with a media-compatible substance. Two additional pads provide the temperature-measuring electrical connection (Kelvin-Point).

The BP + T sensor is also geometrically compatible with the BP0001 and overall BP Series configurations. The 3D-Model files are available for the verification of this integration capability.

Blood Pressure + Temperature Series

Applications

Merit Sensor’s devices are currently used in several novel lung support therapies and blood pressure sensors as part of lightweight and portable emergency response cardiopulmonary support systems.

The blood pressure sensors from Merit Sensor Systems are high quality and can handle the pressure peaks encountered in ECMO applications. Additionally, the sensors are cost-effective, even for disposable medical devices.

Contact Merit Sensor to find out which of its pressure sensors is the best option for your blood pressure monitoring application and how to benefit from its technical expertise and support.

Merit Sensor’s robust, reliable sensors offer clinical experts the highest quality assurance for medical applications.

References and Further Reading

  1. Elliott, W. J. (2003). The Economic Impact of Hypertension. The Journal of Clinical Hypertension, 5(3), 3–13. https://doi.org/10.1111/j.1524-6175.2003.02463.x
  2. Patel, A. R., Patel, A. R., Singh, S., Singh, S., & Khawaja, I. (2019). Applied Uses of Extracorporeal Membrane Oxygenation Therapy Different modes of ECMO therapy. Cureus, 11(7), e5163. https://doi.org/10.7759/cureus.5163
  3. Mossadegh, C. (2017). Monitoring the ECMO. In: Mossadegh, C., Combes, A. (eds) Nursing Care and ECMO. Springer, Cham. https://doi.org/10.1007/978-3-319-20101-6_5
  4. Turner, J. R., Viera, A. J., & Shimbo, D. (2015). Ambulatory Blood Pressure Monitoring in Clinical Practice: A Review. The American Journal of Medicine, 128(1), 14–20. https://doi.org/10.1016/j.amjmed.2014.07.021