Ballistocardiography: Under the Hood
Piezoelectric sensors are devices that convert changes in pressure, strain, temperature, and acceleration into electrical charge. These sensors can be embedded in common objects such as a chair or a bed to provide a graphical representation of heartbeat-induced micro-movements of the human body.
This method of monitoring the vital statistics of patients using piezoelectric sensors is based on the principle of Ballistocardiography (BCG). It is a non-invasive technique that is used to produce a graphical representation of the repetitive motions of the human body. With every heartbeat, the body recoils with the ejection of blood into the pulmonary artery. These cardiogenic movements of the body can be monitored with high levels of accuracy.
BCG measurements are taken by analyzing several wave patterns that originate from the ballistic collision of blood against the wall of the pulmonary artery, most notable of which are the ‘I’, ‘J’ and ‘K’ waves. Although the origin of these waves is unknown, it is possible to create simple mathematical models of the BCG waveform. This allows doctors to monitor the heart activity of a patient to determine the cardiovascular health and onset of diseases making it an effective tool for remote patient monitoring (RPM) services.
BCG as an Effective Tool for Remote Patient Monitoring
Recent applications of BCG have been centered around the advancements that have happened with Piezoelectric sensors. By combining the efficiency and accuracy of these sensors with the power of new digital data processing methods such as big data analytics, researchers have managed to achieve previously unexplored levels of reliability and precision in the monitoring of the cardiac activity of a patient. RPM equipment based on ballistocardiography can now predict diseases related to heart contractility and indicate the onset of abnormalities in heart activity by recording BCG waveforms.
BCG enables measurements without the need for medical staff which greatly reduces the stress caused by medical examinations in a patient, thereby also reducing their involuntary psychophysiological responses. Such effectiveness of BCG based RPM services is set to revolutionize personalized healthcare shortly.
Current Challenges with Remote Patient Monitoring
Existing technologies for RPM services use sensors that are mounted to the body of the patient. Despite paving the way for revolutionary means of monitoring patient health, the combination of wearable sensors and software packages to monitor the vital signs of a patient can be a source of failure and false alarms, themselves. The other operational challenges that are associated with current RPM services as follows:-
Patient Acclimatization to Sensors and Wearable Devices: Comfort, usability, water-resistance, and ease of use are the four primary challenges that patients come across when participating in an RPM program. Not all patients find the constant use of wearables comfortable, which can botch the effectiveness of a care plan that leverages RPM services to improve patient outcomes.
Data Accuracy: RPM systems require calibration from time to time along with software updates for the systems that drive them. This leaves them susceptible to issues related to accuracy when they are not updated as per the schedule set by the manufacturer.
Training and Adaptability: The complexity of RPM devices and multiplicity of sensors that are an integral part of them requires patients to be trained. This further increases the difficulty levels involved in getting patients to adapt to RPM initiatives.
Network Availability and Connectivity: Most RPM devices are wifi enabled or require a network that is capable of transmitting data packets to the device and the computer that drives them. Interruptions in these networks could hamper treatment, especially in the case of patients with serious heart conditions such as arrhythmia.
Adopting BCG in RPM Services
Chair and bed-based systems based on embedded piezoelectric films comprising of homogeneous surface layers are already out on the market. These films are made up of multiple thin thermoplastic polymer layers with air voids in them. When pressure is applied on these layers, the deformation in the arrangement of the air voids creates electrical charges. The fluctuation in these electrical charges caused by the micromovement of the body can be constantly monitored to gather biological parameters and vital signals of a patient.
This enables doctors to measure the heart rate variability (HRV) and blood pressure variability (BPV), two critical parameters which present significant indications about the cardiovascular activity. BPV, in particular, correlates closely with organ damage and triggers of vascular events that lead to cardiac arrest. The sensitivity of the piezoelectric devices used in the monitoring of these patient vitals makes them more accurate and reliable.
With the increased adoption of BCG based kits in RPM services, the costs involved in the manufacture of piezoelectric sensors is poised to go down due to the increase in demand for these devices. Since they are not required to be worn at all times and are simple to install and use, patients would hardly take any time to get used to them. Moreover, their inconspicuous nature and accuracy in monitoring cardiac health make them a seamless fit into the efforts of the existing RPM initiatives from care providers in the current industry settings.
Amit Manral