[P300 latency in patients with respiratory insufficiency due to sequelae of pulmonary tuberculosis].

We studied latent (mild) pulmonary encephalopathy in 14 patients with mild chronic respiratory insufficiency due to the sequelae of pulmonary tuberculosis. All of the patients were between 49 and 62 (mean age: 57.9). None of them had any impairment of daily activities and apparently had a clear consciousness. First, the P300 component evoked by auditory stimuli was examined. Immediately after that, the PO2, PCO2, pH were measured. Then the Hasegawa's dementia scale, the mini-mental state, the "Kanahiroi" test, Zung's depression score, digit span test were also assessed in the 14 patients. P300 components in 7 age-matched normal volunteers were also examined and compared with those in the 14 patients. The mean P300 latency in the patients were significantly prolonged compared with that in the normal volunteers (p less than 0.01). The P300 latency was well correlated with the PCO2, PO2, pH. The results of the "Kanahiroi" test also correlated with these parameters. We suggest that patients with mild respiratory insufficiency due to the sequelae of pulmonary tuberculosis often have latent (mild) pulmonary encephalopathy, and that P300 latency and the "Kanahiroi" test are very useful to detect and evaluate such latent pulmonary encephalopathy.