Biosciences, Bioengineering, and Pharmaceutical Research

SwRI provides expertise in electronics design, software and algorithm development, and research in optics, materials engineering, and testing aimed at the development of new types of medical instrumentation. SwRI's laboratories are used to test the safety and efficacy of new medical devices in order to meet the regulatory requirements of government agencies in domestic and international markets. In addition, Institute bioscientists measure the effects of candidate drugs to increase effective delivery and allow biotechnical and pharmaceutical companies to begin human clinical trials.

Bioengineering

Heat stroke, a serious and sometimes fatal illness, can occur in individuals subjected to extreme heat and humidity without protection. SwRI engineers have developed a handheld heat stress monitor that combines environmental readings with programmed personal data to calculate optimum work and rest cycles and hourly water intake requirements for an individual. The device measures ambient air temperature, relative humidity, solar radiation, and wind speed. Efforts are under way to miniaturize the device and enhance its functionality with field-upgradeable software and sensors to measure barometric pressure and altitude. The finished device will weigh less than one pound and will be small enough to fit in a typical shirt pocket.

SwRI engineers have developed a handheld heat stress monitor that measures air temperature, relative humidity, solar radiation, and wind speed. Engineers are miniaturizing the device to be small enough to fit in a shirt pocket and weigh less than one pound.

The Institute continued to develop devices and improve methods for measuring cardiac output. Typical cardiac measurements are taken by injecting cold saline (injectate) through a pulmonary artery catheter into the right atrium (RA) of the heart. Blood temperature is measured over time downstream in the pulmonary artery (PA) in order to determine cardiac output. Conventional cardiac output computers measure the injectate temperature externally, or outside the body, before it is injected into the catheter. SwRI software engineers developed an algorithm for a revolutionary cardiac output computer that determines cardiac output based on PA blood temperature distribution and injectate temperature, measured within the RA, which alleviates the need for external injectate temperature sensors. The software also simultaneously displays graphs of the temperature changes of the blood within the PA and the injectate temperature through internal catheter temperature sensors. In a clinical study of the cardiac output computer for which SwRI provided technical expertise, physicians demonstrated the effectiveness of the algorithm in producing accurate and reproducible cardiac output readings. Physicians also showed how the software algorithm, with its ability to display the various temperature waveforms, effectively facilitated clinician training and quality control measures.

Heart pacemakers now contain microprocessors to control the patient's heartbeat. Physicians today can communicate with the pacemaker's microprocessors noninvasively. The procedure, called programming, uses a separate device known as a programmer to transmit commands to the implanted unit. This allows the physician to modify the pacemaker therapy to match the changing needs of the patient. SwRI software engineers have developed the software for an advanced touch-screen programmer. The software, being "mission critical," contains sophisticated checks to prevent mis-programming. The software is expected to be complete before the end of 1997.

Building on the Institute's experience in cardiovascular monitoring, engineers are developing an inexpensive method for measuring cardiac output, combining sophisticated signal processing techniques with commonly available patient data to determine this measurement of the heart's pumping ability.

The Institute evaluated the performance and biocompatibility of new oximeters and cardiopulmonary bypass equipment in human blood using laboratory bench blood flow circuits. In vitro bench circuits control blood oxygen saturation, total hemoglobin, pH, blood flow rate, and temperature within specified limits. Scientists measured blood properties including cell counts, hemolysis, and clotting rates from specimens removed from the circuit. Using a bench circuit, Institute engineers also evaluated the biocompatibility of a blood substitute under development for use in open heart surgery. The blood substitute was exposed to cardiopulmonary bypass equipment such as tubing, connectors, and filters. Results of the study were used to gain approval for use of the blood substitute in clinical trials.

Heart catheters require safety and efficacy data prior to market approval. SwRI designed and fabricated a custom test system for a client to simulate the mechanical and electrical conditions experienced within the heart. Using the system, engineers conducted long-term failure analysis of catheters being developed to map electrical impulses of the heart.

Research and development resumed for improving the accuracy and monitoring capabilities of the SwRI oscillometric blood pressure monitoring method. In recent years, this widely used blood pressure measurement method has been combined with electrocardiogram (ECG) and pulse oximeter measurements to produce multifunction patient monitors. This has provided the opportunity to use information from the ECG and pulse plethysmograph to produce more accurate blood pressure measurements. Further, rule-based logic methods, combining information from all three measurements, have been applied to provide the caregiver with more informative descriptions of the patient's health status. SwRI's initial work has produced three patent applications, and work in progress is expected to produce further advancements in critical care patient monitoring.

Often, the amount of blood pumped by the heart, or cardiac output, must be monitored continually when patients are in intensive care units or operating rooms. Through an internal research project, Institute engineers and scientists are developing a sophisticated computer algorithm that continually computes cardiac output by using blood pressure measurements. These measurements are cost-effective and can be read noninvasively.

SwRI bioengineers are combining common physiological measurements such as electrocardiograms, cardiac outputs, blood pressure levels, and blood oxygen content levels taken in hospital intensive care units to produce new patient status information for the physician. These new information systems not only detect clinical problems as they occur, but can predict problems before they occur, allowing physicians and other health care providers to monitor more patients and respond more quickly to anticipated problems.

Biosciences

SwRI bioscientists administered candidate drugs to primates with the potential to revolutionize the treatment of serious diseases such as Parkinson's disease, Alzheimer's disease, cancer, and AIDS. State-of-the-art methods, such as magnetic resonance imaging (MRI), are used to produce individualized coordinates for a cannula which is entered into the lateral ventricle of the brain to infuse the candidate drugs. Additional SwRI studies measured the effects of various candidate drugs on the cardiovascular, immune, hematopoietic, and central nervous systems as well as general health. The results of SwRI safety assessments can be critical to gaining Food and Drug Administration approval to begin human Phase I drug trials.

In a continued study with the University of Texas Health Science Center at San Antonio, scientists used a novel neurobehavioral task to measure cognitive and performance abilities in rodents with different histories of exposure to toluene. Rodents received different toluene exposures and were evaluated to examine how the initial, acute effects of the chemical altered the effects of subsequent low-dose exposure. These studies will help scientists better understand chemical sensitivity problems related to Gulf War syndrome and other neurological disorders.

In a new experiment, SwRI bioscientists performed specialized in vivo tests on baboons to develop and test the safety of a new generation of blood thinners that help in the treatment and prevention of stroke, heart attacks, and other clotting disorders.

To increase the effectiveness of chemotherapy and to better understand its side effects, SwRI scientists evaluated the interactions and dosing schedules of several anti-cancer drugs in an animal model. Researchers investigated how multiple anti-cancer drugs could influence the length of time each drug stays in the body, which could be used to increase drug effectiveness.

1997 Annual Report SwRI Home