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.
Congenital central hypoventilation syndrome (CCHS) is a disorder that affects breathing. People with this disorder take shallow breaths (hypoventilate), especially during sleep, resulting in a shortage of oxygen and a buildup of carbon dioxide in the blood.n some milder cases, CCHS may be diagnosed later in life. In addition to the breathing problem, people with this disorder may have difficulty regulating their heart rate and blood pressure, for example in response to exercise or changes in body position.