title: Changes of regional cerebral oxygen saturation during spinal anesthesia.
abstract: BACKGROUND
  During spinal anesthesia, hemodynamic status is routinely monitored, but this may not give an accurate assessment of cerebral oxygenation. Cerebral oximetry, facilitated by using a near-infrared spectroscope, is a way of estimating regional cerebral oxygen saturation (SrO2). We designed this prospective clinical study to determine whether the changes in mean arterial pressure (MAP) and heart rate (HR) could predict changes in SrO2 during spinal anesthesia.
  
  
  METHODS
  The study sample available for analysis included 45 patients, ASA class I to II, who were scheduled for elective ureteroscopic surgery requiring spinal anesthesia. Spinal anesthesia was performed with 12 mg 0.5% hyperbaric bupivacaine injected intrathecally via L3-4 or L4-5 interspace. MAP, HR, oxygen saturation by pulse oximeter, and SrO2 by near-infrared spectroscope were recorded every 2 min throughout the procedure.
  
  
  RESULTS
  SrO2 was tested by the Shapiro-Wilk test and the results departed from the multivariate normal distribution. The method of generalized estimating equations (GEE) was then used to estimate the model. The output of the GEE analysis for the time-lag model showed that there were relationships between SrO2 and two predictors (MAP and HR) with the correction of the baseline values. All the parameters were significant at a level of 5%. The effects of the decreases of MAP and HR on SrO2 lasted continuously for at least 6 min.
  
  
  CONCLUSIONS
  Based on the time-lag pattern between two predictors (MAP and HR) and SrO2 during spinal anesthesia, we ventured to conclude that a change in MAP or HR caused a significant decrease in SrO2. Since no patient developed any neurologic complication perioperatively, further study must be performed to elucidate the clinical importance of our findings.
authors.affiliation: Department of Anesthesiology, Mackay Memorial Hospital, Taitung, ROC.
authors.forename: Li-Chuan
authors.initials: LC
authors.lastname: Chu
authors.forename: Yung-Wei
authors.initials: YW
authors.lastname: Hsu
authors.forename: Tzu-Chi
authors.initials: TC
authors.lastname: Lee
authors.forename: Yuan-Chi
authors.initials: YC
authors.lastname: Lin
authors.forename: Chun-Jen
authors.initials: CJ
authors.lastname: Huang
authors.forename: Chien-Chuan
authors.initials: CC
authors.lastname: Chen
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Hung
mesh_terms: D000328:Adult; D000368:Aged; D000775:Anesthesia, Spinal; D001794:Blood Pressure; D001921:Brain / Q000378:metabolism*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000378:metabolism*; D011446:Prospective Studies
chemical_list: D010100:Oxygen