Department of Anesthesiology and Critical Care Medicine
Chief, Division of Adult Anesthesia
The Johns Hopkins University School of Medicine
Sheikh Zayed Tower
1800 Orleans Street
Baltimore, MD 21287
The primary focus of Dr. Hogue’s research is the study of methods to improve outcomes from cardiovascular surgery with a particular focus on brain and kidney injury. In particular, he and his colleagues are investigating methods to monitor cerebral blood flow autoregulation noninvasively and in real time. Normally, blood flow to the brain is kept constant across a range of blood pressures to ensure adequate blood flow that meets the metabolic demands of the brain. This process is termed cerebral autoregulation. When blood pressure is below the limits of autoregulation, blood flow to the brain is directly related to blood pressure: the lower the blood pressure, the lower the blood flow. This condition could predispose patients to stroke, especially those who have cerebral vascular disease. Conversely, when blood pressure is above the upper limit of autoregulation, brain blood flow exceeds metabolic needs. This condition may lead to brain edema and possibly cerebral microembolisms that contribute to brain injury.
Dr. Hogue and collaborators at the University of Cambridge, England, have developed a method to monitor cerebral autoregulation noninvasively by using near-infrared spectroscopy (NIRS). Two, self-adhesive sensors are placed on the patient’s forehead and connected to an oximetry monitor. Clinical and laboratory experiments have shown that processing of the NIRS signals collected provides an acceptable surrogate for monitoring changes in cerebral blood flow. Hogue and his colleagues believe that the this approach can be used to optimize an individual patient’s blood pressure to avoid loss of cerebral autoregulation, particularly during procedures such as cardiopulmonary bypass.