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.
Labored breathing is distinguished from shortness of breath or dyspnea, which is the sensation of respiratory distress rather than a physical presentation. Still, many simply define dyspnea as difficulty in breathing without further specification, which may confuse it with e.g. labored breathing or tachypnea (rapid breathing). Labored breathing has occasionally been included in the definition of dyspnea as well.