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.
An abnormal type of breathing seen especially in comatose patients, characterized by alternating periods of shallow and deep breathing. Cheyne-Stokes respiration (CSR) an abnormal pattern of respiration, characterized by alternating periods of apnea and deep, rapid breathing. The respiratory cycle begins with slow, shallow breaths that gradually become abnormally rapid and deep.