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Biochemical Adaptations to Early Extrauterine Life
Published in Emilio Herrera, Robert H. Knopp, Perinatal Biochemistry, 2020
José M. Medina, Carlos Vicario, María C. Juanes, Emilio Fernández
Transition to the extrauterine life is associated with striking changes in the metabolism of the newborn. Thus, during gestation most of fetal requirements are fulfilled by the mother who supplies not only the nutrients necessary for fetal development but also carries out thermogenesis and waste product excretion. However, immediately after delivery the newborn has to take over these metabolic duties and face a fat-rich diet such as milk the metabolism of which depends on sophisticated biochemical processes. These extraordinary changes require special and synchronous mechanisms which must account for the modulation of metabolism toward the proper adaptation of the newborn to the new biochemical environment. In addition to these changes, the brain has to continue its development under these circumstances. This is the case of the human and rat brain which accomplish full maturation after delivery. In these species the adaptations to extrauterine life have to be compatible with brain development; if not, the finest modulation of biochemical mechanism would eventually result in a seriously handicapped newborn. It should be stressed that any step omitted in brain development cannot be regained and would result in permanent damage to the newborn.
Hypoglycaemia in the newborn
Published in Michael S. Marsch, Janet M. Rennie, Phillipa A. Groves, Clinical Protocols in Labour, 2020
Michael S. Marsch, Janet M. Rennie, Phillipa A. Groves
Healthy term babies, particularly those who breastfeed on demand, have significantly lower blood glucose concentrations than formula fed babies in the first 2-3 days of life.1 They also have raised ketone body concentrations, reflecting their ability to mobilize alternative sources of fuel for energy. This is part of the normal physiological adaptation to extrauterine life by the newborn.
Etiology of Neonatal Respiratory Distress Syndrome and the Assessment of Lung Maturity
Published in Jacques R. Bourbon, Pulmonary Surfactant: Biochemical, Functional, Regulatory, and Clinical Concepts, 2019
Michel Dehan, Jeanne Francoual, Marie Claire Imbert, Benoit Denizot
Several factors account for the particular frequency of RD in the neonatal period, including the complexity of mechanisms which allow adaptation to extrauterine life; the disclosure of abnormalities which were silent in utero; the fragility and lability of the mechanisms controlling homeostasis; the susceptibility of neonates to infections; and last but not least, principally in the prematurely born infant, the immaturity of respiratory function. This means that a large number of illnesses, whether of respiratory or of extrapulmonary origin, may have consequences on respiratory gas exchanges. Their issues are potentially critical, mostly at the brain level. The purpose of this chapter is to present briefly the diverse types of RD and their etiologies, with particular emphasis on the idiopathic respiratory distress syndrome (RDS) of the newborn. The central role of surfactant is considered on the one hand for its implication in the physiopathology of the disease and on the other as a specific criterion for evaluating fetal or neonatal lung maturity.
Clinical considerations when treating neonatal aspiration syndromes
Published in Expert Review of Respiratory Medicine, 2019
Andrea Calkovska, Daniela Mokra, Vladimir Calkovsky, Katarina Matasova, Mirko Zibolen
The neonatal airways are safeguarded by protective and defensive airway reflexes, but differences exist between full-term and preterm neonates. In neonates with a mean gestational age of 34 weeks and physiological adaptation to extrauterine life, Kratschmer apneic reflex would be possible to evoke in response to chemical stimulation of the nasal trigeminal afferents with menthol fumes and nasal drops [2]. Mechanical stimulation of the nasal mucosa can elicit a modified sneeze reflex without pronounced deep inspiration, which is typical for sneezing later in life. During oropharyngeal stimulation, the inspiratory component of responses is intensified with respect to amplitude and duration. It was suggested that these independent inspiratory reactions may, to some extent, be co-responsible for the high incidence of aspirations in the neonatal period. In premature neonates with respiratory distress syndrome (RDS), the expulsive component of sneezing and crying is weaker, with the inspiratory component of sneezing and coughing stronger than in controls without RDS [11].