An Experimental Study on the Changes of Rabbit EEG by Reoxygenation after the Exposure to Carbon Monoxide

BACKGROUND: Hyperbaric oxygen (HBO) therapy is applied for the treatments of various diseases inducing hypoxic states. However, reoxygenation of previously hypoxic tissue results in significant tissue damages through the mechanisms of oxygen toxicity. The authors investigated the characteristics of the EEG changes by hyperbaric oxygenation after the exposure to carbon monoxide, and the protective effects of allopurinol, an inhibitor of xanthine oxidase (XO), to the brain. METHODS: Sixty eight male rabbits of New Zealand white weighing 1,350-2,000 gm, were used. The rabbits were divided in 4 groups and measured EEG for 21 hours of experiments. RESULT: The delta waves were significantly increased and alpha waves significantly decreased, during CO exposure, HBO exposure only, and HBO exposure after CO exposure (P< 0.05 in all groups). The wave changes were most remarkable in CO-HBO group, and in this case the changes continued to the last period of the ambient air exposure stage. The brain injury did not decrease as appeared in EEG changes in rabbits treated with allopurinol. This result suggests that many other mechanisms might be involved in CO-HBO condition. The paroxysmal electrical discharges were mostly appeared during or after HBO exposure stages. CONCLUSION: The changes of EEG characteristic in hyperbaric oxygenation are the increase of delta wave and electrical paroxysmal discharges. There is no protective effect of allopurinol to the brain, which suggests that many other mechanisms other than XO might be involved.

Analysis of Contaminated Ground Water Inducing Methemoglobinemia and Epidemiologic Investigation of Contaminated Ground Water

PURPOSE: Drining of Nitrate-contaminated water has been the most common cause of acquired methemoglobinemia. We had cyanotic infant diagnosed as methemoglobinemia caused by feeding with powdered formula mixed with nitrate-contaminated ground water. METHODS: We had done epidemiologic investigation to identify the cause of an infant's methemoglobinemia. Analysis of ground water and blood test of involved family members and neighbors were performed RESULTS: Analysis of the 8 household ground water revealed high level of nitrate(29837 ppm), indicating contamination of water as the cause of methemoglobinemia. We had done blood tests to evaluate the methemoglobin level of 65 people in the neighborhood ; among them, there was no infant and we could not find another cyanotic case of methemoglobinemia. They had normal blood level of methemoglobinemic concentration. CONCLUSIONS: If ground water will be used for drinking water, especially for formula water, epidemiologic investigation and analysis of ground waters should be recommended.

Epidemiologic investigation to identify the cause of an infant methemoglobinemia / 예방의학회지

Epidemiologic investigation was conducted on January, 1993 in Seoul to identify the cause of an infant methemoglobinemia. Field investigation of the area of outbreak, survey of household and family members, analysis of ground water, and blood tests of involved family members were performed. Following results were obtained. On analyzing the quality of the ground water on patients's household high levels of nitrate was found indicating contamination of water as the cause of a methemoglobinemia outbreak. On analyzing the quality of the ground waters on seven other places within the neighborhood five were contaminated by nitrate in concentration that exceeded the permissible limit implying presence nearby source of contamination. Sources of contamination were thought to be originating from human waste in conventional bathroom facilities, chicken manure used in nearby orchards and plant fields or fertilizers. But the results of water analysis with presence of bacteria or E.coli, concentration of potassium, phosphate and the past history of diarrhea among family members, chicken manure suggested the most possible source of contamination. To evaluate the health status of members in the neighborhood past history was reviewed revealing no prior existence of patient with cyanosis and 65 people in the neighborhood had normal levels of methemoglobin concentration in their blood. Conclusively, the ground water on patient's household was contaminated with nitrate and despite provision of adequate water supply, family members of the patient along with distrust in the water supply system had used ground water as their source of drinking water resulting of methemoglobinemia. Many suburban area of Seoul and country side thought to be having similar problems concerning contaminated ground water supply and dormant outbreak of patients as a result of the drinking of the contaminated water. Epidemiologic investigation and water analysis of ground waters are advised.