Fetal Asphyxia and the Primate Colony in Puerto Rico

Abstract

From an historical perspective, asphyxia in the newborn infant presents a number of issues. Although defined as “pathological changes caused by lack of oxygen in respired air, resulting in hypoxia and hypercapnia” (Dorland 2007, p. 167), the term is used differently by physiologists, clinicians, and pathologists. In Greek the term means “a stopping of the pulse,” thus strictly speaking, the word asphyxia is an “infelicity of etymology” (Eastman 1936b, p. 274). As with many definitions, however, once it has been accepted, it may be altered to fit the circumstances. For instance, obstetrical asphyxia is “an imprecise term… frequently based on low Apgar scores alone…” (Cunningham et al. 1989, p. 597). Some prefer the term “neonatal or perinatal depression” (Reece and Hobbins 2007, p. 1234). According to a task force of the World Federation of Neurology Group, it is a “… condition of impaired blood gas exchange leading, if it persists, to progressive hypoxemia and hypercapnia” (Bax and Nelson 1993, p. 1022). For the neonatologist, asphyxia is applied to “infants who require more than one minute of positive pressure ventilation before the occurrence of sustained respiration.” No reference is made to blood gas values. In contrast, hypoxia is the case in which deficient oxygen in the blood (hypoxemia) is associated with the O₂ supply to tissues being reduced below physiologic levels, despite adequate perfusion. Commonly associated with conditions of impaired placental exchange of O₂, asphyxia may result from abruptio placentae [premature separation of the placenta from the uterine wall], prolapse of the umbilical cord, maternal shock with hypotension, carbon monoxide intoxication, and other conditions. As noted below, a link between reduced fetal oxygenation and the development of perinatal complications such as intrauterine growth restriction and subsequent neurodevelopmental handicaps has long been established (Figs. 5.1 and 5.2).