Bethesda, MD -- Sleep apnea/hypopnea syndrome is characterized by repetitive upper airway obstruction with ensuing cyclical hypoxia, or a decreased level of oxygen in the blood. Repetitive hypoxia is followed by persistently increased ventilatory motor output, commonly referred to as long-term facilitation (LTF). This excitatory mechanism occurs after repetitive stimulation of the carotid bodies as ventilation returns to baseline over a long duration, up to several hours.
LTF is drawn out by repetitive hypoxia during sleep, but only in those who snore regularly and have evidence of inspiratory (timed during inhalation) flow limitation during sleep. Given the occurrence of repetitive hypoxemia in patients with sleep apnea, researchers set out to investigate the occurrence of LTF in patients with obstructive sleep apnea/hypopnea syndrome (OSA).
A new study tested the hypothesis that episodic hypoxic exposure activates LTF in OSA patients during stable non-rapid eye movement (NREM) sleep. The study was undertaken by inducing repetitive hypoxia in OSA patients using nasal continuous positive airway pressure (CPAP) to maintain upper airway patency and stable sleep state for the duration of the experiments.
The authors of the study, Long-term Facilitation in Obstructive Sleep Apnea Patients During NREM Sleep, are Salah E. Aboubakr, Amy Taylor, Reason Ford, Sarosh Siddiqi, and M. Safwan Badr, all from the Medical Service, John D. Dingell Veterans Affairs Medical Center, and the Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan. The study is published in the December 2001 edition of the Journal of Applied Physiology.
The 11 test subjects selected or this study had recently documented and untreated sleep apnea. Subjects with other medical problems, such as daytime hypoxemia or cor pulmonale (hypertr
Contact: Donna Krupa
American Physiological Society