[Cardiovascular adaptation of the newborn to stress situations: effects of hypoxia on newborn and 14-day-old piglets (author's transl)].

-Newborn and 14-day-old piglets (in a developmental stage equivalent to that of a 3-month-old infant) compensate sustained hypoxemia by increasing cardiac performance. -This compensation can be maintained for only roughly 30 min. -Newborn piglets free from hypoxemia are able to tolerate the stress of anesthesia, artificial respiration, and operation significantly longer than those with additional hypoxemia. -14 day-old piglets without hypoxemia are not able to tolerate the stress of anesthesia, artificial respiration, and operation longer than those with additional hypoxemia. -The reactions of the cardiovascular system to anesthesia, artificial respiration, and operation in present or absent additional hypoxemia are qualitatively identical and are also identical in time in the newborn hypoxic, the 14-day-old hypoxic, and normoxic animals, whereas they appear significantly later in newborn control piglets.