Nobukatsu Takasu

Report on 640 victims of the Tokyo subway sarin attack

Abstract [Okumura T, Takasu N, Ishimatsu S, Miyanoki S, Mitsuhashi A, Kumada K, Tanaka K, Hinohara S: Report on 640 victims of the Tokyo subway sarin attack. Ann Emerg Med August 1996;28:129-135.] See related editorial, Chemical Agent Terrorism.

Asymptomatic sequelae to acute sarin poisoning in the central and autonomic nervous system 6 months after the Tokyo subway attack

Abstract Six to eight months after the Tokyo subway attack in March 1995, the neurophysiological effects of acute sarin poisoning were investigated in 18 passengers exposed to sarin (sarin cases) in the subways to ascertain the focal or functional brain deficits induced by sarin. The event-related and visual evoked potentials (P300 and VEP), brainstem auditory evoked potential, and electrocardiographic R-R interval variability (CVRR), together with the score on the posttraumatic stress disorder (PTSD) checklist, were measured in the sarin cases and the same number of control subjects matched for sex and age. None of the sarin cases had any obvious clinical abnormalities at the time of testing. The P300 and VEP (P100) latencies in the sarin cases were significantly prolonged compared with the matched controls. In the sarin cases, the CVRR was significantly related to serum cholinesterase (ChE) levels determined immediately after exposure; the PTSD score was not significantly associated with any neurophysiological data despite the high PTSD score in the sarin cases. These findings suggest that asymptomatic sequelae to sarin exposure, rather than PTSD, persist in the higher and visual nervous systems beyond the turnover period of ChE; sarin may have neurotoxic actions in addition to the inhibitory action on brain ChE.

Chronic neurobehavioral effects of Tokyo subway sarin poisoning in relation to posttraumatic stress disorder.

Chronic neurobehavioral effects of acute sarin poisoning were evaluated in 9 male and 9 female patients who were exposed to sarin poisoning in the Tokyo subway incident in Japan. The investigators used nine neurobehavioral tests, as well as a posttraumatic stress disorder checklist, 6-8 mo after the poisoning occurred. Serum cholinesterase activity in patients on the day of poisoning (i.e., March 20, 1995) ranged from 13 to 131 IU/l (mean=72.1 IU/l). The results of analysis covariance, in which age, education level, alcohol consumption, and smoking status (covariates) were controlled in 18 sarin cases and in 18 controls, showed that the score on the digit symbol (psychomotor performance) test was significantly lower in the sarin cases than in controls. Nonetheless, the scores for the General Health Questionnaires, fatigue of Profile of Mood States, and posttraumatic stress disorder checklist were significantly higher in the sarin cases than controls. The investigators added posttraumatic stress disorder to the covariates, and only the score on the digit symbol test was significantly lower in sarin cases. In addition, the results of stepwise multiple regression analysis in 18 sarin cases revealed that scores for the General Health Questionnaires, fatigue of Profile of Mood States (i.e., fatigue, tension-anxiety, depression, and anger-hostility)-together with the paired-associate learning test-were associated significantly with posttraumatic stress disorder. The association did not remain significant for the digit symbol test score. Perhaps a chronic effect on psychomotor performance was caused directly by acute sarin poisoning; on the other hand, the effects on psychiatric symptoms (General Health Questionnaire) and fatigue (Profile of Mood States) appeared to result from posttraumatic stress disorder induced by exposure to sarin.

Chronic neurobehavioral and central and autonomic nervous system effects of Tokyo subway sarin poisoning.

To evaluate delayed (prolonged) neurobehavioral and neurophysiological effects of acute sarin poisoning, nine male and nine female patients of the Tokyo subway sarin poisoning in Japan were examined by neurobehavioral tests, posttraumatic stress disorder (PTSD) checklist, brain evoked potentials, computerized static posturography, and electrocardiographic R-R interval variability, 6-8 months after the poisoning. Their serum cholinesterase activities on the day of the poisoning (March 20, 1995) were 13-131 (mean 72.1) IU/L. The results suggested delayed effects on psychomotor performance, the higher and visual nervous system and the vestibulo-cerebellar system with psychiatric symptoms resulting from PTSD.

A preliminary study on delayed vestibulo-cerebellar effects of Tokyo Subway Sarin Poisoning in relation to gender difference: frequency analysis of postural sway.

To evaluate delayed (long-term) effects of acute sarin poisoning on postural balance, nine male and nine female victims of the Tokyo Subway Sarin Poisoning in Japan (sarin cases) were examined by computerized posturography 6-8 months after the poisoning. Their plasma cholinesterase activities (ChE) on the day of the poisoning (March 20, 1995) were 13-95 (mean 68.2) IU/l for females and 19-131 (mean 75.9) IU/l for males, which were not significantly different between the two sexes. In females, the postural sway of low frequency (0-1 Hz) in the anterior-posterior direction and area of sway with eyes open was significantly larger in the cases than in the controls. Romberg quotients for the low-frequency sway in the anterior-posterior direction for females and low-frequency sway and length of sway in the medio-lateral direction for males were significantly related to log ChE. It is suggested that a delayed effect on the vestibulo-cerebellar system was induced by acute sarin poisoning; females might be more sensitive than males.

A New Method for Predicting the Outcome and Survival Period in Paraquat Poisoning

1 To elucidate the importance of lung damage in the prognosis of paraquat poisoning, the respiratory index (RI: A-aDO2/PO2) was analysed in 51 patients with paraquat poisoning. 2 Progressive deterioration of the RI was observed in 43 non-survivors, but not in 8 survivors. In addition, the RI of non-survivors became greater than 1.5 in the course of their poisoning, while that of the survivors remained less than 1.5. 3 The level of the RI (i.e. whether it became greater than 1.5 or not) was found to be a good indicator for the prognosis for life. 4 The RI-time, defined as the time taken from ingestion for the RI to be greater than 1.5, was found to be a good indicator for predicting the survival period in fatal cases. 5 As a result, we conclude that it is important and useful to examine a series of RI and the RI-time in poisoned patients not only to provide proper respiratory care, but also to predict outcome and survival period.

Evaluation of Severity Indexes of Patients with Paraquat Poisoning

1 Three indexes for evaluating the severity of paraquat poisoning based on plasma-paraquat concentration are presently in use; the curves of Proudfood et al. and Scherrmann et al. and the SIPP. Their effectiveness in determining the prognosis of patients with paraquat poisoning was evaluated. 2 To determine which index was more accurate, contingency tables of the three indexes were obtained and compared; Proudfoots curve vs the SIPP Scherrmanns curve vs the SIPP. Proudfoots curve and the SIPP were applied to patients admitted within 24 h after intoxication. Scherrmanns curve and the SIPP were applied to patients admitted more than 24 h after intoxication. The proportions of patients with true positive and true negative results to total patients were compared by a ratio test. 3 Proudfoots curve was found to be more accurate than the SIPP for predicting the prognosis of patients admitted within 24 h (P < 0.05). No significant difference, however, was noted between Scherrmanns curve and the SIPP in determining the prognosis of patients admitted after more than 24 h. 4 In conclusion, Proudfoots curve proved a better index for predicting the outcome of patients who were admitted within 24 h. However, for the prognosis of patients admitted more than 24 h after the ingestion of paraquat, further study is required.

Acute and chronic effects of sarin exposure from the Tokyo subway incident

The Tokyo subway sarin attack was the second documented incident of nerve gas poisoning in Japan. The St. Lukes International Hospital received 640 patients on the day of the attack. Reduction in plasma cholinesterase (ChE) activity was generally associated with the severity of acute signs of toxicity. With time and treatment, the value rose quickly. To evaluate possible residual signs of symptoms 1 year after the attack, we sent questionnaires to the victims; of 303 respondents, 45% still had some symptoms including eye problems, easy fatigability, headache, and fear. Therefore, we conducted a study in collaboration with investigators at the Tokyo University Department of Public Health to evaluate possible long-term neuropsychological sequelae. The findings suggest the need to closely follow such patients for possible persistent functional changes.

Necrotizing Fasciitis Rapidly Diagnosed by Aspiration Cytology

A case of necrotizing fasciitis caused by beta hemolytic streptococci is reported. A 66‐year‐old man was admitted because of pain and swelling in the right buttock. Rapid application of aspiration cytology made it possible to diagnose necrotizing fasciitis with bacterial infection. Unfortunately, however, the patient died of cardiac arrest due to hyperpotassemia 11 h after admission. Mortality from this disease is most often related to failure in recognizing it early. Rapid diagnosis and early treatment is mandatory in order to save the patients’life. We emphasize the usefulness of rapid aspiration cytology, despite the unfortunate outcome in the present case. Acta Pathol Jpn 41: 567 572, 1991.

Lessons Learned from the Tokyo Subway Sarin Attack

On the morning of 20 March 1995, sarin was released in the Tokyo Subway System. There had never been such a large scale act of urban terrorism using a nerve gas. There are many lessons to be learned from Tokyo Subway Sarin Attack. Two major lessons can be cited in summary: 1) Absence of decontamination — In total, 1,364 EMTs were dispatched, and among them, 135 were secondarily affected. At St. Lukes hospital, 23% of the medical staff complained of symptoms and signs of secondary exposure. Fortunately, nobody died from the secondary exposure. The religious cult used a 30% sarin solution. If they had used a 100% sarin solution, the outcome would have been much more tragic — secondarily exposed prehospital and medical staff would have been killed. This is the reason for the development of decontamination facilities and the use of personal protective equipment (PPE) in the prehospital and hospital settings; and 2) Confusion of information and lack of coordination among related organizations — Japan is a highly vertically structured society. Fire departments, police, metropolitan governments, and hospitals acted independently without coordination. After the attack, the Japanese government developed the Severe Chemical Hazard Response Team. The Prime Ministers office created a National Security and Crisis Management Office that calls realistic desktop hazmat drills involving the concerned organizations and specialists.