amnion. the innermost fetal membrane, which forms a sac filled with amniotic fluid that surrounds the embryo and later the fetus; as it enlarges it gradually obliterates the chorionic cavity and enfolds the umbilical cord. Called also bag of waters.
cluster breathing. cluster breathing. a breathing pattern in which a closely grouped series of respirations is followed by apnea. The activity is associated with a lesion in the lower pontine region of the brainstem. See also Biot's respiration, Cheyne-Stokes respiration.
Mixed apnea. â¢ A of the event, followed by a gradual increase in effort which eventually breaks the apnea. Hypopnea: â¢ Partial airway collapse causing shallow breathing (airflow reduced by at least 30-50%) during sleep, lasting 10 seconds or longer, usually associated with a fall in blood oxygen saturation.