Ambulatory Blood Pressure Monitoring

Whilst 24-hour ABPM observation is routine, there are several shortcomings with the current generation of automated oscillometric measurement systems. The root of many of these shortcomings is in the use of traditional motor-driven diaphragm pumps, which are bulky, noisy, vibrate and introduce pulsation in the airflow. Disc Pump from TTP Ventus is a novel, piezoelectric micropump whose unique combination of features addresses many of the disadvantages of diaphragm pumps, enabling compact, silent, arm-worn modules, measurement on inflation and constant inflation rates.

Measurement on inflation
Unlike conventional pumps, Disc Pump does not introduce pulsation in the airflow, allowing the oscillometric signal to be measured during cuff inflation. This has the added benefit that the cuff pressure need not exceed the systolic pressure by much, minimising the compression forces applied to the patient.

Constant inflation rate
Thanks to its high-precision control, Disc Pump can be controlled to deliver a constant inflation rate—this can be time-based (mmHg per second) and mirror the rule-of-thumb 2-3 mmHg/s deflation rate used by many systems (see graph for example), or a pulse-rate based adaptive approach (mmHg per heartbeat). The ability to control (and adapt) the inflation rate allows system designers to optimise the measurement for each patient, thereby maximising accuracy.

Graph: blood pressure measurement taken during cuff inflation with Disc Pump, with the pump controlled to achieve a constant inflation rate of 3 mmHg/s. The lack of pulsation from the pump enables clear measurement of the arterial pulse pressure, from which the oscillation envelope and blood pressure can be extracted.

Create compact wearable systems
Disc Pump weighs just 5 g (1/5 oz) and occupies a volume of 7 cm3, allowing it to be integrated into a module on the brachial cuff—thereby enabling the removal of the bulky pump module, its strap, and the hose connecting it with the cuff.

Improved accuracy
The removal of the host linking the cuff and pump isn't just advantageous to the user experience. Given that any inadvertent pressure applied to this hose can interfere with the measurement, the revised architecture offers a more robust solution - not least during the night, when the hose can become kinked during sleep.

Silent operation
Disc Pump's ultrasonic operation is inaudible and vibration-free, allowing the pump module to operate with disturbing the user's sleep—allowing the system to capture a true picture of blood pressure during an uninterrupted night.

Above: Traditional 24-hour ambulatory blood pressure systems have a belt or strap-worn pump module connected to a brachial cuff via a long hose, which can be inconvenient to the user. Disc Pump, on the other hand, is compact, lightweight, and does not create sound or vibration during operation – enabling it to be mounted directly onto a brachial cuff.

How can I test the pump?
Our standard series configuration models (XP-S2-007 and BL-S2-012) are best suited to blood pressure applications—with our high-flow variants of those models suitable for more demanding requirements (XP-S2-028 and BL-S2-030).

For initial testing, we offer an evaluation kit which contains everything you need to get started, including two pumps, drive electronics, PC software (configuration, control and datalogging) and an accessories kit. The drive electronics can be controlled in a variety of ways, including providing a 0 to 2.5V signal that can be mapped to a pressure target; the evaluation kit can then control the output of the pump to reach the target pressure. This opens up the ability to carry out constant rate inflation testing, by supplying a triangle or saw-tooth waveform to the analog input.

Head over to our products page to learn more about our product range, download datasheets and to request a quotation today.

TTP Ventus' Disc Pump Evaluation Kit

learn more about the evaluation kit