Using Pressure Transducers for Noninvasive Heart and Respiratory Monitoring

Abstract

Detecting heart and respiratory rates is an essential means of providing emergency medical care. Current methods of detecting such signals include the widely used electrocardiography (ECG) method. Other more manual methods of heart and respiratory rate estimation require a practitioner to constantly observe the patient. These methods are time consuming and detract valuable time from emergency medical care. This thesis presents a novel, hands off, heart and respiratory monitor (HARMONI). It uses pressure transducers and medical tubing placed on a person's chest. The tubing is plugged off at one end, and then attached to a pressure transducer at the other end. The transducer sees spikes in voltage whenever the pressure inside the tubing changes. Heart and respiratory rates both cause expansion in the chest, increasing the pressure in the tubing, and causing the transducer to see a change in voltage. The method was first validated, and then tested in a simulated environment. Finally, the device was transformed in to a full system prototype. Human tests were conducted to correlate the signal with that of an industry standard ECG device. This thesis explains how heart and respiratory rates can be derived using signal processing techniques and a simple non-invasive sensor. This device is a rapidly deployable tool that has the potential to save lives specifically in mass casualty situations. It would be a force multiplier, allowing a single responder to monitor multiple casualties, saving time and lives.