Pupil diameter for confirmation of brain death in adult organ donors in Japan

Aim The criteria for brain death in Japan include a bilateral pupil diameter of ≥4 mm. We evaluated the appropriateness of a 4-mm pupil diameter in adult brain-dead donors in Japan. Methods We retrospectively reviewed the records of 148 consecutive adult brain-dead donors with an average age of 46 years. All records were anonymously registered to the Japanese Ministry of Health, Labour and Welfare (the Japanese Ministry of Health and Welfare before 2001) from the various designated emergency institutes that performed organ donation under brain death from 1999 to 2012 in Japan. Results All donors had a Glasgow Coma Scale score of 3, absence of all seven brain stem reflexes, an isoelectric electroencephalogram for >30 min, and apnea as tested by the standard method. All of these examinations were repeated approximately 6 h later for confirmation. The pupil diameter (average ± standard deviation) was 6.1 ± 1.1 mm at the first assessment and 6.4 ± 1.1 mm approximately 6 h later. The 95% probability distribution as calculated by statistical analysis was 3.93-8.30 mm in the left eye and 3.88-8.28 mm in the right eye in the first assessment, and 4.25-8.58 mm in the left eye and 4.32-8.43 mm in the right eye approximately 6 h later. Conclusion Despite the various original causes of brain death, we conclude that a pupil diameter of ≥4 mm is a reasonable criterion for brain death in adults.