title: Pupil diameter and light reaction during cardiac arrest and resuscitation.
abstract: OBJECTIVE
  Traditionally, both pupil diameter and reaction to light have been examined to confirm the diagnosis of death. In the present study, we investigated quantitative changes in pupil diameter and light reaction for assessing the efficacy of cardiopulmonary resuscitation (CPR) and as a predictor of outcome.
  
  
  METHODS
  Controlled experimental study.
  
  
  METHODS
  Animal research laboratory at a university-affiliated research institute.
  
  
  METHODS
  Fifteen domestic male pigs weighing between 33 and 40 kg.
  
  
  METHODS
  Ventricular fibrillation was induced with an alternating current delivered to the right ventricular endocardium. After 7 mins of untreated ventricular fibrillation, chest compression and mechanical ventilation were initiated and maintained for 6 mins. Restoration of spontaneous circulation then was attempted by electrical defibrillation.
  
  
  RESULTS
  Spontaneous circulation was reestablished in 9 of 15 animals. Pupils were fully dilated, and pupillary reaction to light was absent in 7 of the 9 resuscitated animals during untreated cardiac arrest. Progressive decreases in pupil diameter were observed together with restoration of light reaction during CPR, in each animal that was successfully resuscitated. When the pupils remained dilated and unreactive after 6 mins of CPR, resuscitation efforts were uniformly unsuccessful. A highly significant linear correlation between coronary perfusion pressure generated during precordial compression and pupil diameter was documented. Both were predictive of outcome.
  
  
  CONCLUSIONS
  Dynamic changes of pupil diameter and reactions to light during cardiac arrest and resuscitation were correlated with coronary perfusion pressure, and both predicted the likelihood that spontaneous circulation and cerebral function would be restored.
authors.affiliation: Institute of Critical Care Medicine, Palm Springs, CA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Zhao
authors.forename: M H
authors.initials: MH
authors.lastname: Weil
authors.forename: W
authors.initials: W
authors.lastname: Tang
authors.forename: K
authors.initials: K
authors.lastname: Klouche
authors.forename: S R
authors.initials: SR
authors.lastname: Wann
mesh_terms: D000818:Animals; D016009:Chi-Square Distribution; D006323:Heart Arrest / Q000150:complications* / Q000628:therapy*; D008297:Male; D010775:Photic Stimulation; D011237:Predictive Value of Tests; D011681:Pupil Disorders / Q000209:etiology*; D012151:Resuscitation / Q000379:methods*; D013552:Swine