Effect of hypoxia on periodic limb movement in sleep related breathing disorders

Introduction: the relationship between periodic limb movements during sleep (plms) and sleep related breathing disorder (srbd) is not clear. factors affecting the occurrence of plms in patients with srbd,and a possible relation of plms and sleep related hypoxia in patients with obstructive sleep apnea syndrome and sleep related hypoventilation-hypoxemic syndromes was investigated. methods: patients with snoring and/or witnessed apnea were tested with polysomnography. respiratory events and plms were scored. serology and arterial blood lactate levels were measured. results: 80 patients,58 male and 22 female were included (mean age: 49.1 years,sd: 9.0). 62 had srbd and 18 had no srbd,where 29 were in periodic limb movement index over and equal to 15 (plmi≥15) group and 51 were in the plmi below 15 (plmi<15) group. the rate of sleep-time spent below 90% oxygen saturation (t90%) and t80% were significantly higher in patients with plmi≥15 than patients with plmi<15. plmi<15 group spent longer time in nrem iii than plmi≥15 group. apnea hypopnea index,the rate of sleep-time spent below 90% oxygen saturation (t90%),t80%,t70%,ess and sleep nrem i-ii% were significantly higher in patients with plmi≥15 plus srbd,than patients with plmi≥15 without srbd. plmi was not correlated with overnight lactate change. conclusion: as the rate of sleep-time spent below 90% oxygen saturation is longer in patients with plmi≥15 than plmi<15,hypoxemia may play role in the pathophysiology of plms. further studies with nasal cpap treatment would reveal more information about the etiopathogenesis of plms in srbd.