Plasma norepinephrine in sleep apnea syndrome

In 8 male patients suffering from sleep apnea syndrome, plasma norepinephrine (NE) levels were examined. At 22.00 and at 6.30 blood samples were obtained. In 3 cases, plasma NE levels displayed little changes between 22.00 and 6.30. In 2 cases, plasma NE levels at 6.30 increased 20% compared with those at 22.00. In 3 cases, plasma NE levels at 6.30 increased more than 40%. No significant correlation between apnea index and plasma NE levels was observed. Total time under 90% arterial oxygen saturation (SaO2) significantly correlated with the ratio of plasma NE levels at 6.30 to those at 22.00. In 2 cases of the 8 patients blood samples were drawn hourly (22.00-6.00) and at 6.30. In these 2 cases, when SaO2 decreased, plasma NE levels tended to increase. It is concluded that in sleep apnea syndrome plasma NE levels increased during sleep and did not correlate with apnea index but with oxygen desaturation.