Patient-centric design for a medical device will enhance user adherence and satisfaction but should not come at the cost of device functionality. This can create a tricky balancing act for designers, who strive for smaller, quieter, more precise systems.
In this example, we look at several shortcomings with the current generation of Ambulatory Blood Pressure Monitoring [ABPM] devices – otherwise known as automated oscillometric measurement systems – and demonstrate how swapping out certain components can simplify the system architecture to achieve a more patient-centric device design.
Assessing Device Performance – The Current Standard
During a 24-hour ABPM observation, a patient’s blood pressure is measured at regular intervals throughout the day and night as they go about their normal daily business. The measurements taken help healthcare professionals build an accurate patient health profile and diagnosis.
Current ABPM devices involve the patient wearing a cuff around their arm that is connected via tubing to a portable device, worn around the neck or waist. These ABPM systems commonly use traditional motor-driven diaphragm pumps that rely on the bulk compression of air within a cavity to create pressure, which, in turn, creates a pulsed flow, noise and vibration.
Resulting devices can be bulky, noisy, and uncomfortable. They can also skew readings through design fault – for example, kinks in the tubing when the patient is sleeping can interrupt cuff inflation and void measurements.
Collaborating with our Customers
Early on we identified that incorporating a disc pump into an ABPM system provided opportunities for our customers to elevate their device design.
This is because, in contrast to conventional air pumping mechanisms, the disc pump doesn’t rely on the bulk compression of air within a cavity. Instead, the micropump generates a high amplitude, high frequency acoustic standing wave in a specially designed acoustic cavity. The pump runs at a frequency of around 21kHz, a frequency above the range of human hearing and as it cycles at over 21,000 times per second, the resultant air flow is effectively pulsation free. The piezo drive also has very little mass and inertia so the pump can respond to set point changes within just a few milliseconds, helping to improve system response times and control.
As a result, it is possible to measure the oscillometric signal whilst inflating the cuff. The cuff pressure need not exceed the systolic pressure by much, minimising the compression forces applied to the patient.
By taking the measurement on inflation, you remove the need for a check valve to hold the pressure as seen in traditional BPM systems. Using a disc pump can also remove the need for a proportional valve that is often used to control the vent speed in the cuff.
To further help with the integration and reduction of system size, we created a manifold that incorporated a disc pump and a valve for a ‘plug ‘n’ play’ solution that integrates with other components quickly & easily.
Due to the silent operation and lack of mechanical vibration with disc pump, our customers can:
- Create a fully integrated, arm-worn pump module with a compact and lightweight form that is MRI compatible
- Enhance measurement accuracy with the removal of the hose and the added ability to drive adaptive inflation rates
- Improve patient comfort through silent operation and the ability to carry out BP measurement on inflation due to lack of mechanical vibration
- Simplify system architecture with the removal of components to miniaturise the system
Testing Made Easy with The Development Kit
Our Development Kit allows you to evaluate both the valves and disc pumps so you can be up and running with a test BPM system in no time at all.
From that point onwards, we can walk you through a typical design journey integrating a disc pump and valves, as well as provide direct and sustained engineering support and free resources to help with all aspects of development.
If you have a project you are interested in using disc pump in, get in touch, or if you would like to learn more about our Development Kit, click here.
