Relationship between pupil size and acetylcholinesterase activity in patients exposed to sarin vapor.

Intensive care medicine

PubMedID: 9347376

Nozaki H, Hori S, Shinozawa Y, Fujishima S, Takuma K, Kimura H, Suzuki M, Aikawa N. Relationship between pupil size and acetylcholinesterase activity in patients exposed to sarin vapor. Intensive Care Med. 1997;23(9):1005-7.
OBJECTIVE
To elucidate the effect of sarin vapor on pupil size and erythrocyte acetylcholinesterase activity (AchE).

DESIGN
Retrospective observational survey.

SETTING
Emergency department of an urban teaching hospital.

PATIENTS
80 patients who were exposed to sarin in a terrorist attack in Tokyo subways.

MEASUREMENTS AND RESULTS
Pupil size and AchE activity on the day of exposure were measured. Among the 80 patients, the pupils were miotic (< 3 mm) in 50 patients (62.5%), while AchE activity was below the normal range (< 1.2 U) in 34 patients (42.5%). AchE was significantly lower in the miotic group than in the group with normal pupils (1.0 +/- 0.5 U vs 1.5 +/- 0.3 U, p < 0.01). In the miotic group, AchE activity was lower than normal in 32 patients (64.0%) but was decreased in only 2 patients in the normal pupil group (6.7%) (p < 0.01).

CONCLUSIONS
Miosis is a more sensitive index of exposure to sarin vapor than erythrocyte AchE. Systemic poisoning is apparently less likely to develop if the patient's pupil size is normal on arrival at the hospital.