A newborn is lying in a crib near an exterior wall and large window in winter.
The infant's temperature is 97.0°F (36.1°C). Which heat loss mechanism is responsible?
Convection.
Radiation.
Evaporation.
Conduction.
The Correct Answer is B
Choice A rationale
Convection involves the loss of heat due to air currents moving across the infant's skin. While some air movement is always present, the primary risk for heat loss associated with proximity to a large cold exterior wall and window in a winter environment is the transfer of heat to those large, unheated, non-contact surfaces through radiation, not typically a draft.
Choice B rationale
Radiation is the transfer of heat from a warm object (the infant) to a cooler solid object (the exterior wall and large window) that is not in direct contact with the body. These large, cold surfaces act as heat sinks, causing the infant to lose body heat significantly via electromagnetic waves, a major mechanism of heat loss in a crib placement next to an outside wall.
Choice C rationale
Evaporation is the heat loss caused by the vaporization of moisture (like sweat or bath water) from the skin surface. While this mechanism is always a factor, it is not primarily responsible for the temperature drop in this specific scenario, which emphasizes the environmental factors of the cold wall and window near the crib.
Choice D rationale
Conduction involves the loss of heat through direct contact with a cooler surface, such as the crib mattress or cold linens. Since the scenario describes the infant being near an exterior wall and window, which are not touching the infant, conduction is not the mechanism responsible for this particular drop in temperature.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A rationale
Mild irritability and crying are non-specific signs that can occur for various reasons in a newborn. While they may accompany overheating, they are not the most immediate and critical indicators of a severe thermal regulation problem requiring emergency intervention compared to physiological signs of excessive heat.
Choice B rationale
Slight sweating in a newborn is generally an unreliable or late indicator of overheating because neonates have immature sweat glands, especially in the first few days of life, and their primary mechanism for heat loss is evaporation, not sweating. Therefore, relying on this finding alone could lead to a delayed response to a potentially dangerous rise in core temperature.
Choice C rationale
An axillary temperature of 99.8°F (37.6°C) is slightly elevated but remains within or very close to the upper limits of the normal range for a newborn, which is typically considered to be 97.7°F to 99.5°F (36.5°C to 37.5°C). While requiring monitoring, this temperature does not indicate a hyperthermic crisis as severely as the combination of flushed skin and tachycardia.
Choice D rationale
Flushed skin is a sign of peripheral vasodilation, an attempt by the body to increase heat loss, and an increased heart rate (tachycardia) is a compensatory response to metabolic stress and increased oxygen demand caused by the elevated core temperature. These are immediate and highly concerning signs of hyperthermia, indicating that the body's compensatory mechanisms are actively engaged and immediate cooling measures are necessary to prevent neurological injury.
Correct Answer is B
Explanation
Choice A rationale
A newborn should typically feed every 2 to 3 hours, or 8 to 12 times in a 24-hour period. Sleeping for 8 hours straight between feedings, especially in the early weeks, may indicate insufficient milk intake, especially if the baby has not regained birth weight, and should be reported to a healthcare provider.
Choice B rationale
Adequate output is the most reliable indicator of sufficient milk transfer and intake in the newborn. A baby who is content after most feedings and produces 6 to 8 wet diapers (urine should be pale/clear) and 3 to 4 loose, yellow stools in a 24-hour period by day 4 of life is generally receiving enough breast milk.
Choice C rationale
Newborns usually experience a normal physiologic weight loss, losing 5.
Choice D rationale
While feeding frequently is normal, only feeding every 3 to 4 hours may not be adequate for all newborns, especially in the first few weeks as the mother establishes her milk supply and the baby is learning to feed. Newborns should be fed on demand whenever they show feeding cues, which is often 8 to 12 times a day.
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