Computational Physiology Laboratory

Center for Biomedical Engineering University of Kentucky

Research in this laboratory uses advanced methods of signal processing and computational modeling to detect and diagnose abnormal physiological behaviors that result from disease or injury. Our current interests focus on: (i) heart and brain injury resulting from carbon monoxide poisoning, and; (ii) abnormal electrical activation of the brain associated with sleep-disordered breathing. Our research involves intensive mathematical modeling using the ACSL simulation suite and Comsol Multiphysics, and state-of-the-art signal processing using MATLAB and IDL.

Research Projects

Carbon Monoxide (CO) Poisoning

Carbon monoxide -- a colorless, tasteless and odorless gas -- is often referred to as an invisible killer as it is difficult to detect. CO is generated in toxic amounts by internal-combustion engines, faulty fossil-fuel heating systems, fires, and emissions from automobiles. CO poisoning kills ~4000 persons per year in the US. Also, exposure to carbon monoxide continues to be a significant occupational health concern. In fact, CO is the most common cause of work-related inhalation fatalities. CO binds to hemoglobin molecules in the blood and inhibits their ability to transport oxygen from the lungs to body tissues. The morbidity and mortality resulting from CO exposures are due primarily to the effects of severe lack of oxygen on the heart and central nervous system.

Our current work in this area focusses on the use of mathematical models to predict the degree of impairment of oxygen delivery to the heart and brain in CO poisoned patients.

Our recent publications in this area:

• Bruce, E. N., M. C. Bruce, and K. Erupaka. Prediction of the Rate of Uptake of Carbon Monoxide From Blood by Extravascular Tissues. Respir. Physiol. Neurobiol. 161: 142-159, 2008.
• Bruce, M. C., and E. N. Bruce. Analysis of factors that influence rates of carbon monoxide uptake, distribution, and washout from blood and extravascular tissues using a multicompartment model. J. Appl. Physiol. 100(4): 1171-1180, 2005.
• Erupaka K., M. C. Bruce, and E. N. Bruce. Extravascular Burden of Carbon Monoxide (CO) During CO Exposure and Washout, Society for Mathematical Biology, Raleigh, NC; Aug. 1-4, 2006.
• Bruce, E. N., and M. C. Bruce. A multicompartment model of carboxyhemoglobin and carboxymyoglobin responses to inhalation of carbon monoxide. J. Appl. Physiol. 95: 1235-1247, 2003.

  Learn more about our research on CO poisoning by clicking on Carbon Monoxide Research on our home page.

  Sleep and EEG Research

  Sleep-disordered breathing (SDB) is a clinical abnormality in which a patient experiences repeated episodes of insufficient breathing during sleep. These events can lead to inadequate levels of blood oxygen (hypoxia), which may cause tissue injury in the brain, and to arousals, which disrupt sleep and cause sleep fragmentation. Serious SDB occurs in about 4% of the population, being more prevelant in males, and mild SDB may be present but largely undiagnosed in 15% of the population. Obstructive sleep apnea syndrome (OSAS) is a form of SDB in which breathing is reduced or blocked by obstruction of the upper airway due to encroachment of soft tissues into the airway lumen. Aging is associated with major changes in the quality of sleep. The resulting problems are widespread, as more than 80% of adults 65 yr and older report some degree of sleep disruption. The incidence of sleep fragmentation and the frequency of arousals and awakenings increase significantly with age. Hypoxia and sleep fragmentation each contribute to the neurological and related morbidities asociated with SDB and aging - memory and executive impairment, psychosocial difficulties, daytime sleepiness, and excessive rate of accidents. Our current work in this area focusses on diagnosing the causes and consequences of SDB through novel signal processing of electroencephalogram (EEG) signals.

  Our recent publications in this area:

  Bruce, E. N. Mechanisms and consequences of sleep apnea and periodic breathing. European Union "Marie Curie Training Event ", Biomedical Modeling and Cardiovascular-respiratory Control, University of Graz, Austria; Aug. 1-4, 2007.

  Mathew B, Hudgel D, Bruce M, and Bruce E. Entropy of electroencephalogram (EEG) signals varies with sleep state. Experim. Biology Conf., San Francisco, CA, April 1-4, 2006.

  Alonso, J. F., M. A. Mañanas, D. Hoyer, Z. L. Topor, E. N. Bruce. Evaluation of Respiratory Muscles Activity by means of Cross Mutual Information Function at Different Levels of Ventilatory Effort. IEEE Trans Biomed Engrg (in press)

  Learn more about our research on EEG analyses in sleep by clicking on EEG/Sleep Research on our home page. The link Sleep apnea/Control of breathing contains PDF files of some of our papers related to control of breathing in sleep.