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Pupil diameter and light reaction during cardiac arrest and resuscitation

Zhao, Danhong MD, PhD; Weil, Max Harry MD, PhD, FCCM; Tang, Wanchun MD, FCCM; Klouche, Kada MD; Wann, Shue-Ren MD

Laboratory Investigations

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.

Design Controlled experimental study.

Setting Animal research laboratory at a university-affiliated research institute.

Subjects Fifteen domestic male pigs weighing between 33 and 40 kg.

Interventions 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.

Measurements and Main 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.

From the Institute of Critical Care Medicine (Drs. Zhao, Weil, Tang, Klouche, and Wann), Palm Springs, CA; and the Keck School of Medicine of the University of Southern California (Drs. Weil and Tang), Los Angeles, CA.

Supported, in part, by grant RO1 HL-54322 from the National Institutes of Health, Heart, Lung and Blood Institute, and by the Rosse Family Charitable Foundation.

Eye signs served as a noninvasive, real-time indicator of the effectiveness of cardiopulmonary resuscitation and predicted the likelihood of successful resuscitation.

© 2001 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins