Bioengineering

SwRI provides expertise in medical device design and product development, including software and algorithm development, electronics design, product packaging, and testing. The Institute continues its leadership in blood pressure, cardiac output, pulse oximetry, and vital signs monitor development. SwRI's Bioengineering Department became ISO 9001 and EN 46001 certified in 1998. Taking advantage of the Institute's multidisciplinary strengths, SwRI scientists and engineers this year applied numerical modeling techniques to quantify differences in the risk of ejection seat injuries among male and female military aviators.

Institute biomedical engineers are collaborating with San Antonio neonatologists to develop an intelligent software program to identify apnea, or cessation of breathing, in premature infants. Up to half of prematurely born babies develop serious apnea problems and must be closely monitored in neonatal intensive care units. Automated detection of apnea would not only reduce workload, but also provide for more timely alerts when the problem occurs.

The Institute continues to design and develop software for cardiology applications. The field of heart electrophysiology (EP) has seen the development of numerous new technologies and patient treatments. Software serves an integral role in many of the new EP devices, which include implantable cardioverter defibrillators (ICD) and radio frequency ablation catheter systems. In the hospital, large amounts of data are collected during many of these new EP procedures. The Institute provided networking and database expertise for a hospital information system that serves as a central repository for cardiology data. SwRI software engineers also supplied expertise for the design and development of pacemaker programmers. Physicians use programmers to noninvasively transmit commands, such as heart rate settings, to an implanted pacemaker.

Balloon angioplasty in the carotid arteries to the brain involves significant risks. Blood clots and other particles may be dislodged by the inflated balloon, travel to the brain, and cause a stroke. The OmniFilter™, a patented percutaneous guidewire microfilter product, is designed to convert a standard guidewire into a temporary filter to prevent blood clots from reaching various organs of the body. The guidewire microfilter is positioned downstream from a balloon catheter to capture unsafe particles dislodged during angioplasty procedures. The Institute is translating the design concept into a medical product able to collect particles while maintaining adequate blood flow, and without causing injury to the blood vessel.

Pulse oximeters have found rapid acceptance among medical practitioners who value their ability to monitor the amount of oxygen, in terms of percent of capacity, in the blood. However, it is difficult for current pulse oximeters to function properly when in motion resulting from factors such as the patient moving a hand, shivering, or being transported in an emergency vehicle. Institute bioengineers are developing computer algorithms that remove these motion indications from the oximeter signals, allowing the device to compute oxygen saturation even during significant motion. The unique design of the motion artifact rejection system allows for easy integration into new or existing pulse oximeters.

Institute engineers have continued to improve the accuracy and capabilities of the SwRI oscillometric blood pressure monitoring system. The system uses electrocardiogram and pulse oximeter measurements to correct for errors produced by abnormal heartbeats (arrhythmia) and rapidly changing blood pressure during measurement. The SwRI-developed methods have been incorporated into medical monitoring products expected to reach the market following regulatory approval.

The Institute's extensive bioengineering test facilities provide for a wide range of laboratory and bench-top biocompatibility tests. Here, a new oxygenator for a cardiopulmonary bypass system is being tested in a flow loop using human blood.

Blood pressure measured on the arm or wrist is different from the blood pressure at the heart. Alterations in blood pressure are produced by the mechanics of wave propagation through the arteries and, as a result, peripheral blood pressures do not always accurately represent a patient's cardiovascular state. SwRI engineers have developed methods for noninvasively determining the central aortic blood pressure. Using mathematical models of the cardiovascular system to correct radial blood pressure signals, these innovative methods are able to produce accurate, continuous estimates of aortic pressure.

For the Naval Air Warfare Center (NAWC), SwRI engineers are working to quantify the increase, or decrease, in risk of injury between male and female pilots. Because ejection systems are designed for the average male aviator, it is possible that females could be more prone to injury during ejection because of their smaller physical size. Since many injuries localize in the cervical (neck) spine region, SwRI has begun work to develop a numerical model from computerized tomography scan "slices" from a representative set of males and females. Uncertainties, whether due to the systematic size difference between males and females or to the inherent randomness in configuration of the spinal components or physical properties, will be simulated by analyzing the model using SwRI-developed advanced probabilistic analysis techniques. With the difference in risk of injury between male and female pilots in hand, NAWC will be better equipped to recommend changes in ejection systems to reduce risks for female aviators.

1998 Annual Report SwRI Home