title: Using the relationship between brain tissue regional saturation of oxygen and mean arterial pressure to determine the optimal mean arterial pressure in patients following cardiac arrest: A pilot proof-of-concept study.
abstract: Prospectively assess cerebral autoregulation and optimal mean arterial pressure (MAPOPT) using the dynamic relationship between MAP and regional saturation of oxygen (rSO2) using near-infrared spectroscopy.
  
  
  
  Feasibility study of twenty patients admitted to the intensive care unit following a cardiac arrest. All patients underwent continuous rSO2 monitoring using the INVOS(®) cerebral oximeter. ICM+(®) brain monitoring software calculates the cerebral oximetry index (COx) in real-time which is a moving Pearson correlation coefficient between 30 consecutive, 10-s averaged values of MAP and correspond rSO2 signals. When rSO2 increases with increasing MAP (COx ≥0.3), cerebral autoregulation is dysfunctional. Conversely, when rSO2 remains constant or decreases with increasing MAP (COx <0.3), autoregulation is preserved. ICM+(®) fits a U-shaped curve through the COx values plotted vs. MAP. The MAPOPT is nadir of this curve.
  
  
  
  The median age was 59 years (IQR 54-67) and 7 of 20 were female. The cardiac arrest was caused by myocardial infarction in 12 (60%) patients. Nineteen arrests were witnessed and return of spontaneous circulation occurred in a median of 15.5min (IQR 8-33). Patients underwent a median of 30h (IQR 23-46) of monitoring. COx curves and MAPOPT were generated in all patients. The mean overall MAP and MAPOPT were 76mmHg (SD 10) and 76mmHg (SD 7), respectively. MAP was outside of 5mmHg from MAPOPT in 50% (SD 15) of the time. Out of the 7672 5-min averaged COx measurements, 1182 (15%) were at 0.3 or above, indicating absence of autoregulation. Multivariable polynomial fractional regression demonstrated an increase in COx with increasing temperature (P=0.008).
  
  
  
  We demonstrated the feasibility to determine a MAPOPT using cerebral oximetry in patients after cardiac arrest.
authors.affiliation: Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Mypinder S
authors.initials: MS
authors.lastname: Sekhon
authors.affiliation: Neurocritical Care Unit, Addenbrooke's Hospital, Cambridge University Hospitals Trust, Cambridge University, Cambridge, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Smielewski
authors.affiliation: Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Tahara D
authors.initials: TD
authors.lastname: Bhate
authors.affiliation: Centre for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada.
authors.forename: Penelope M
authors.initials: PM
authors.lastname: Brasher
authors.affiliation: Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Denise
authors.initials: D
authors.lastname: Foster
authors.affiliation: Neurocritical Care Unit, Addenbrooke's Hospital, Cambridge University Hospitals Trust, Cambridge University, Cambridge, United Kingdom.
authors.forename: David K
authors.initials: DK
authors.lastname: Menon
authors.affiliation: Neurocritical Care Unit, Addenbrooke's Hospital, Cambridge University Hospitals Trust, Cambridge University, Cambridge, United Kingdom.
authors.forename: Arun K
authors.initials: AK
authors.lastname: Gupta
authors.affiliation: Brain Physics Lab, Division of Neurosurgery, Cambridge University Hospitals Trust, Cambridge University, Cambridge, United Kingdom.
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.affiliation: Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: William R
authors.initials: WR
authors.lastname: Henderson
authors.affiliation: Division of Cardiology, Department of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Gin
authors.affiliation: Division of Cardiology, Department of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Graham
authors.initials: G
authors.lastname: Wong
authors.affiliation: Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada; Centre for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada; Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada. Electronic address: donald.griesdale@vch.ca.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Griesdale
mesh_terms: D000368:Aged; D062186:Arterial Pressure / Q000502:physiology*; D001921:Brain / Q000378:metabolism*; D005240:Feasibility Studies; D005260:Female; D006323:Heart Arrest / Q000378:metabolism* / Q000503:physiopathology; D006706:Homeostasis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010100:Oxygen / Q000032:analysis*; D010865:Pilot Projects; D011446:Prospective Studies
chemical_list: D010100:Oxygen
keywords: Cardiac arrest; Cerebral autoregulation; Cerebral oximetry