[A case of obstructive sleep apnea syndrome with increased lung water content during sleep]

A 57-year-old man was admitted complaining of sleep disturbance. All night polysomnography showed a pattern of obstructive sleep apnea. We performed 201Tl scintigraphy to evaluate hemodynamic change and degree of stress on the right ventricle during sleep, and compared it with a 201Tl scintigram during wakefulness. We recognized 201Tl uptake by the lung in the 201Tl scintigram during sleep, but not during wakefulness. To determine the mechanism of 201Tl uptake by the lung during sleep, we measured lung water content during sleep by double indicator dilution method (Nihon Koden, NTV-1100). We recognized an increase of lung water content during sleep. We consider that the increase of lung water content during sleep is caused by sleep apnea, probably by hemodynamic change due to negative pleural pressure swings during sleep apnea.