title: Cerebral desaturation during cardiac arrest: its relation to arrest duration and left ventricular pump function.
abstract: OBJECTIVE
  To determine the impact of brief periods of cardiac arrest (CA) on regional cerebral oxygen saturation (rSO2) in patients with low left ventricular ejection fraction (LVEF <30%).
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Cardiac surgery room at a university hospital.
  
  
  METHODS
  Seventy-seven consecutive patients undergoing elective implantation of a cardioverter/defibrillator in monitored anesthesia care. According to preoperative assessments, left ventricular function was classified as normal (LVEF >50%), moderately impaired (LVEF 30%-50%), or severely reduced (LVEF <30%).
  
  
  METHODS
  None.
  
  
  RESULTS
  rSO2 was determined during threshold testing with concomitant induction of CA. In patients with LVEF <30%, mean baseline rSO2 (59%) was already below the lower range of normal despite normal arterial blood pressure, heart rate, and arterial oxygen saturation. rSO2 increased by 6% after 6 L/min oxygen insufflation (p < 0.05) and dropped again in each group after CA, reaching a nadir after successful defibrillation. Patients with LVEF <30% and baseline rSO2 <63% exhibited the lowest values. They also showed the highest incidence (11%) of critical cerebral desaturations (i.e., >20% drop from baseline or rSO2 value <50%). rSO2 in patients with LVEF <30% was always below that determined in patients with LVEF >30% (p < 0.05). There was a strong correlation between rSO2 values before CA and rSO2 nadir (p < 0.05). The drop in rSO2 was only moderately related to the brief CAs (p < 0.05).
  
  
  CONCLUSIONS
  These findings demonstrate that severely compromised left ventricular pump function is associated with diminished rSO2. As these patients seem to be more susceptible to critical desaturations, they may be prone to severe tissue hypoxemia unless adequate oxygen delivery is reestablished rapidly. This may contribute to the poor neurologic outcome after successful resuscitation in patients with LVEF <30%.
authors.affiliation: Division of Cardiothoracic and Vascular Anesthesia and Intensive Care Medicine, Medical University Hospital Vienna, Austria.
authors.forename: Keso
authors.initials: K
authors.lastname: Skhirtladze
authors.forename: Beatrice
authors.initials: B
authors.lastname: Birkenberg
authors.forename: Bruno
authors.initials: B
authors.lastname: Mora
authors.forename: Andrea
authors.initials: A
authors.lastname: Moritz
authors.forename: Ismail
authors.initials: I
authors.lastname: Ince
authors.forename: Hendrik J
authors.initials: HJ
authors.lastname: Ankersmit
authors.forename: Barbara
authors.initials: B
authors.lastname: Steinlechner
authors.forename: Barbara
authors.initials: B
authors.lastname: Szeinlechner
authors.forename: Martin
authors.initials: M
authors.lastname: Dworschak
mesh_terms: D000368:Aged; D001794:Blood Pressure; D001921:Brain / Q000378:metabolism*; D005260:Female; D006323:Heart Arrest / Q000503:physiopathology*; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D014693:Ventricular Fibrillation / Q000503:physiopathology; D016277:Ventricular Function, Left