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.
Sleep apnea is a common disorder in which patients have one or more pauses in breathing or shallow breaths during sleep. These pauses can last from a few seconds to several minutes, occurring 30 times or more per hour. Typically, normal breathing starts again in conjunction with a loud snort, choking, or gasping sound.