Chapter 19: Normal Newborn: Processes of Adaptation Flashcards
Asphyxia
Low blood oxygen and high blood and tissue carbon dioxide levels
Brown fat
Tissue designed for newborn heat production
Jaundice
Bilirubin staining of the skin and sclerae
Kernicterus
Permanent neurologic damage from bilirubin
Neutral thermal environment
Surroundings in which the infant can maintain a stable temperature with minimal oxygen consumption and a low metabolic rate.
Surfactant
Slippery substance that reduces surface tension in lung alveoli
Explain how each factor helps the newborn initiate respirations:
a. Chemical:
b. Mechanical:
c. Thermal:
d. Sensory:
a. Chemical: Decreased blood oxygen and pH and increased blood carbon dioxide stimulate the respiratory center in the medulla. Cutting the umbilical cord vessels may end the flow of a substance from the placenta that inhibits respirations.
b. Mechanical: Fetal chest compression during vaginal birth forces a small amount of lung fluid from the chest and draws air into the lungs when the pressure is released.
c. Thermal: The sudden change in environmental temperature at birth stimulates skin sensors, which then stimulate the brain’s respiratory center.
d. Sensory: Sensory stimuli to breath include drying, holding, sounds, smells, and light.
Why is adequate functional residual capacity in the lungs important?
Residual air in the lungs allows the alveoli to remain partly expanded after exhalation. This reduces the work necessary to expand the alveoli with each breath.
What are characteristics that predispose newborns to heat loss?
Thin skin; blood vessels near the surface; little insulating subcutaneous white fat; heat readily transferred from internal organs to skin; greater ration of surface area to body mass.
Describe each method whereby the newborn can lose heat. Which can also be methods of heat gain?
Evaporation occurs when wet surfaces are exposed to air and the surfaces dry.
Conduction occurs when the infant has direct contact with a cool surface or object.
Convection refers to heat loss to air currents near the infant.
Radiation refers to heat loss when the infant is near, but not touching, a cold surface.
All methods except evaporation can also be sources of heat gain, such as contact with warm blankets of exposure to warmed air currents or heat from a radiant warmer.
How does brown fat help the newborn maintain body temperature? Under what circumstances can newborns have inadequate brown fat, and why?
Brown fat is metabolized to generate heat, which is transferred to the blood vessels running through it and then circulated to the rest of the body. Infants who may have inadequate brown fat include preterm infants who may not have accumulated brown fat and those with intrauterine grown restriction whose stores were depleted.
Explain the relationship among oxygenation, body temperature, glucose stores, and bilirubin levels in the newborn.
Heat production requires oxygen for metabolism, which can exceed the infant’s capacity to supply the oxygen. Cold stress decreases the production of surfactant, which can cause respiratory difficulty. Glucose use is accelerated when the metabolic rate rises to produce heat, possibly depleting these stores and resulting in hypoglycemia. Metabolism of glucose and brown fat without adequate oxygen causes increased production of acids. These acids may cause jaundice because the interfere with transport of bilirubin to the liver, where it can be conjugate and excreted. Metabolic acidosis could also occur.
Compare normal values for fetal and adult erythrocyte, hemoglobin, and hematocrit levels.
Values for all three are higher in the newborn than in the older infant or adult. The fetus needs these higher levels to supply adequate oxygen to the tissues because the partial pressure of oxygen in fetal blood is lower than in the adult.
How would you explain the prophylactic neonatal vitamin K injection to new parents?
Newborns may have a problem with bleeding because they have a temporary lack of vitamin K, which is necessary for clotting. One injection of vitamin K given shortly after birth provides the newborn with vitamin K until the intestines are able to make it.
What glucose level on a screening test requires further follow-up?
Glucose lower than 40-45 mg/dL