title: The Modified Apnea Test During Brain Death Determination: An Alternative in Patients With Hypoxia.
abstract: BACKGROUND
  Conventional apnea testing in patients with severe hypoxemia or hemodynamic instability with removal from the ventilator support is unsafe. We describe an alternative approach to apnea testing, which may be used in patients with hypoxia unable to undergo conventional apnea testing.
  
  
  METHODS
  Case Report. A 42-year-old man had a severe traumatic brain injury resulting in diffuse cerebral edema and subarachnoid hemorrhage with herniation. His presentation was complicated by hypoxic respiratory failure from pulmonary contusions and hemorrhagic shock. On hospital day 2, the patient lost brain stem reflexes. Brain death testing with conventional apnea testing was attempted but aborted due to hypoxia.
  
  
  RESULTS
  A modified apnea test was applied, which had been approved by appropriate hospital committees including critical care operations, ethics, and the brain death protocol council. Minute ventilation was gradually decreased by ≥50% to attain a PaCo2 level ≥20 mm Hg above baseline. The ventilation mode was then switched from volume control to continuous positive airway pressure while observing the patient for signs of respiration for a duration of 60 seconds.
  
  
  CONCLUSIONS
  The modified apnea test does not require circuit disconnection and can be successfully applied to determine brain death without compromising safety in high-risk patients having severe hypoxia.
authors.affiliation: Department of Neurology (Neurocritical Care), University of Massachusetts Medical School, Worcester, MA, USA.
authors.forename: Aditi
authors.initials: A
authors.lastname: Ahlawat
authors.affiliation: Department of Neurology (Neurocritical Care), University of Massachusetts Medical School, Worcester, MA, USA Department of Surgery, University of Massachusetts Medical School, Worcester, MA, USA.
authors.forename: Raphael
authors.initials: R
authors.lastname: Carandang
authors.affiliation: Department of Anesthesia/Critical Care, University of Massachusetts Medical School, Worcester, MA, USA.
authors.forename: Stephen O
authors.initials: SO
authors.lastname: Heard
authors.affiliation: Department of Neurology (Neurocritical Care), University of Massachusetts Medical School, Worcester, MA, USA Department of Surgery, University of Massachusetts Medical School, Worcester, MA, USA Department of Anesthesia/Critical Care, University of Massachusetts Medical School, Worcester, MA, USA susanne.muehlschlegel@umassmemorial.org.
authors.forename: Susanne
authors.initials: S
authors.lastname: Muehlschlegel
mesh_terms: D000328:Adult; D001049:Apnea / Q000175:diagnosis*; D001784:Blood Gas Analysis / Q000379:methods*; D001926:Brain Death / Q000175:diagnosis*; D001930:Brain Injuries / Q000150:complications* / Q000503:physiopathology; D002245:Carbon Dioxide / Q000032:analysis; D045422:Continuous Positive Airway Pressure; D017809:Fatal Outcome; D006801:Humans; D000860:Hypoxia; D008297:Male; D012119:Respiration; D012129:Respiratory Function Tests / Q000379:methods*
chemical_list: D002245:Carbon Dioxide
keywords: apnea testing; brain death; neurocritical care