Brain injury during cardiac surgery results primarily from cerebral embolism and/or reduced cerebral blood flow (CBF). The latter is of particular concern for the growing number of surgical patients who are aged and/or who have cerebral vascular disease. Normally, CBF is physiologically autoregulated (or kept constant) within a range of blood pressures, allowing for stable cerebral O2 supply commensurate with metabolic demands. Cerebral autoregulation is impaired in patients who are undergoing cardiac surgery and have cerebral vascular disease or many other conditions. Such impairment could lead to brain injury because current practices of targeting low mean arterial blood pressure empirically (usually 50-70 mmHg) during cardiopulmonary bypass (CPB) may expose patients with impaired cerebral autoregulation to cerebral hypoperfusion. The hypothesis of this study is that targeting mean arterial pressure during CPB to a level above an individual's lower autoregulatory threshold reduces the risk for early neurologic complications from cardiac surgery or postoperative cognitive decline. Cerebral autoregulation will be monitored in real time by using software that continuously compares the relation between arterial blood pressure and low-frequency changes in transcranial Doppler measured cerebral blood flow velocity as well as cerebral oximetry measured with near infrared spectroscopy using methods we have validated. The primary endpoint of the study will be a composite outcome of clinical stroke, and/or new ischemic brain lesions detected with diffusion-weighted magnetic resonance (MR) imaging, and/or cognitive decline from baseline at 4 to 6 weeks after surgery. We will further assess for a relationship between blood pressure below the limits of autoregulation and delirium, an end-point associated with morbidity and mortality. Brain injury from cardiac surgery is an important source of operative mortality, prolonged hospitalization, increased healthcare expenditure, and impaired quality of life. Developing strategies to reduce the burden of this complication has wide public health implications and is within the mission of the NHLBI.

Public Health Relevance

Neurological complications from cardiac surgery are an important source of operative mortality, prolonged hospitalization, healthcare expenditure, and impaired quality of life. New strategies of care are needed to avoid rising complications for the growing number of aged patients undergoing cardiac surgery. This study will evaluate novel techniques that could be widely used to reduce brain injury that results from inadequate brain blood flow during surgery.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL092259-06A1
Application #
8757012
Study Section
Clinical and Integrative Cardiovascular Sciences Study Section (CICS)
Program Officer
Charette, Marc F
Project Start
2008-04-01
Project End
2019-06-30
Budget Start
2014-08-08
Budget End
2015-06-30
Support Year
6
Fiscal Year
2014
Total Cost
$316,463
Indirect Cost
$62,543
Name
Johns Hopkins University
Department
Anesthesiology
Type
Schools of Medicine
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21218
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Hori, Daijiro; Hogue Jr, Charles W; Shah, Ashish et al. (2015) Cerebral Autoregulation Monitoring with Ultrasound-Tagged Near-Infrared Spectroscopy in Cardiac Surgery Patients. Anesth Analg 121:1187-93
Maxwell, Bryan G; Hogue Jr, Charles W; Pronovost, Peter J (2015) Does it matter who the anesthesiologist is for my heart surgery? Anesth Analg 120:499-501

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