title: Effects of Moderate Hyperventilation on Jugular Bulb Gases under Propofol or Isoflurane Anesthesia during Supratentorial Craniotomy.
abstract: BACKGROUND
  The optimal ventilated status under total intravenous or inhalation anesthesia in neurosurgical patients with a supratentorial tumor has not been ascertained. The purpose of this study was to intraoperatively compare the effects of moderate hyperventilation on the jugular bulb oxygen saturation (SjO 2 ), cerebral oxygen extraction ratio (O 2 ER), mean arterial blood pressure (MAP), and heart rate (HR) in patients with a supratentorial tumor under different anesthetic regimens.
  
  
  METHODS
  Twenty adult patients suffered from supratentorial tumors were randomly assigned to receive a propofol infusion followed by isoflurane anesthesia after a 30-min stabilization period or isoflurane followed by propofol. The patients were randomized to one of the following two treatment sequences: hyperventilation followed by normoventilation or normoventilation followed by hyperventilation during isoflurane or propofol anesthesia, respectively. The ventilation and end-tidal CO 2 tension were maintained at a constant level for 20 min. Radial arterial and jugular bulb catheters were inserted for the blood gas sampling. At the end of each study period, we measured the change in the arterial and jugular bulb blood gases.
  
  
  RESULTS
  The mean value of the jugular bulb oxygen saturation (SjO 2 ) significantly decreased, and the oxygen extraction ratio (O 2 ER) significantly increased under isoflurane or propofol anesthesia during hyperventilation compared with those during normoventilation (SjO 2 : t = -2.728, P = 0.011 or t = -3.504, P = 0.001; O 2 ER: t = 2.484, P = 0.020 or t = 2.892, P = 0.009). The SjO 2 significantly decreased, and the O 2 ER significantly increased under propofol anesthesia compared with those values under isoflurane anesthesia during moderate hyperventilation (SjO 2 : t = -2.769, P = 0.012; O 2 ER: t = 2.719, P = 0.013). In the study, no significant changes in the SjO 2 and the O 2 ER were observed under propofol compared with those values under isoflurane during normoventilation.
  
  
  CONCLUSIONS
  Our results suggest that the optimal ventilated status under propofol or isoflurane anesthesia in neurosurgical patients varies. Hyperventilation under propofol anesthesia should be cautiously performed in neurosurgery to maintain an improved balance between the cerebral oxygen supply and demand.
authors.forename: Lan
authors.initials: L
authors.lastname: Meng
authors.forename: Shu-Qin
authors.initials: SQ
authors.lastname: Li
authors.forename: Nan
authors.initials: N
authors.lastname: Ji
authors.affiliation: Department of Anesthesiology and Pain Management, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Luo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D062186:Arterial Pressure / Q000502:physiology; D001784:Blood Gas Analysis; D003399:Craniotomy / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006985:Hyperventilation / Q000139:chemically induced* / Q000503:physiopathology*; D007530:Isoflurane / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000008:administration & dosage / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D007530:Isoflurane; D015742:Propofol