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 sleep apnea (both central sleep apnea and obstructive sleep apnea). During sleep, the brain instructs the muscles of breathing to take a breath. Central sleep apnea (CSA) occurs when the brain does not send the signal to the muscles to take a breath and there is no muscular effort to take a breath.