title: Functional near-infrared spectroscopy for the measurement of propofol effects in conscious sedation during outpatient elective colonoscopy.
abstract: Endoscopic procedures performed in the United States routinely involve the use of conscious sedation as standard of care. The use of sedation reduces patient discomfort and anxiety while improving the technical quality of the procedure, and as a result, over 98% of clinicians have adopted the practice. The tremendous benefits of sedation are offset by heightened costs, increased patient discharge time, and cardiopulmonary complication risks. The inherent liabilities of putting patients under sedation have necessitated a large number of physiological monitoring systems in order to ensure patient comfort and safety. Currently American Society of Anesthesiologist (ASA) guidelines recommend monitoring of pulse oximetry, blood pressure, heart rate, and end-tidal CO2; although important safeguards, these physiological measurements do not allow for the reliable assessment of patient sedation. Proper monitoring of patient state ensures procedure quality and patient safety; however no "gold-standard" is available to determine the depth of sedation which is comparable to the anesthesiologist's professional judgment. Developments in functional near-infrared spectroscopy (fNIRS) over the past two decades have introduced cost-effective, portable, and non-invasive neuroimaging tools which measure cortical hemodynamic activity as a correlate of neural functions. Anesthetic drugs, such as propofol, operate by suppressing cerebral metabolism. fNIRS imaging methods have the ability to detect these drug related effects as well as neuronal activity through the measurement of local cerebral hemodynamic changes. In the present study, 41 patients were continuously monitored using fNIRS while undergoing outpatient elective colonoscopy with propofol sedation. The preliminary results indicated that oxygenated hemoglobin changes in the dorsolateral prefrontal cortex, as assessed by fNIRS were correlated with changes in response to bolus infusions of propofol, whereas other standard physiological measures were not significantly associated.
authors.affiliation: School of Biomedical Engineering, Science & Health Systems, Drexel University, Philadelphia, PA, USA. Electronic address: Adrian.B.Curtin@drexel.edu.
authors.forename: Adrian
authors.initials: A
authors.lastname: Curtin
authors.forename: Kurtulus
authors.initials: K
authors.lastname: Izzetoglu
authors.forename: James
authors.initials: J
authors.lastname: Reynolds
authors.forename: Radha
authors.initials: R
authors.lastname: Menon
authors.forename: Meltem
authors.initials: M
authors.lastname: Izzetoglu
authors.forename: Mary
authors.initials: M
authors.lastname: Osbakken
authors.forename: Banu
authors.initials: B
authors.lastname: Onaral
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D002245:Carbon Dioxide / Q000097:blood; D003113:Colonoscopy / Q000379:methods*; D016292:Procedural Sedation; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010045:Outpatients; D015742:Propofol / Q000494:pharmacology*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D055815:Young Adult
chemical_list: D006993:Hypnotics and Sedatives; D002245:Carbon Dioxide; D015742:Propofol
keywords: Outpatient endoscopy; Propofol; Sedation monitoring; fNIRS