The nurse is caring for a neonate undergoing phototherapy. What action does the nurse include on the infant's care plan?

Choice A) dilates the bronchioles, decreasing airway resistance: This is not the correct function of surfactant.

Surfactant is a substance that reduces the surface tension of the fluid that lines the alveoli, which are the tiny air sacs in the lungs where gas exchange occurs. Surfactant does not affect the diameter of the bronchioles, which are the small airways that branch from the bronchi. Bronchodilation and bronchoconstriction are regulated by the autonomic nervous system and various mediators, such as histamine, epinephrine, and acetylcholine.

Choice B) provides transportation for oxygen to enter the blood supply: This is not the correct function of surfactant. Surfactant does not transport oxygen or any other gas. Oxygen diffuses from the alveoli into the capillaries, where it binds to hemoglobin in the red blood cells. The red blood cells then transport oxygen to the tissues via the blood circulation. Surfactant does not play a role in this process.

Choice C) keeps the alveoli open during expiration: This is the correct function of surfactant. Surfactant prevents the alveoli from collapsing during expiration by lowering the surface tension of the fluid that lines them. This allows for easier breathing and better gas exchange. Without enough surfactant, the alveoli tend to collapse and stick together, causing atelectasis, which is a condition where some or all of a lung collapses. Atelectasis can lead to hypoxia, respiratory distress, and infection.

Choice D) causes increased permeability of the alveoli: This is not the correct function of surfactant. Surfactant does not increase or decrease the permeability of the alveoli, which is the ability of substances to pass through them.

Permeability of the alveoli depends on several factors, such as pressure gradients, solubility, molecular size, and membrane thickness. Increased permeability of the alveoli can occur in conditions such as acute respiratory distress syndrome (ARDS), where fluid leaks into the alveolar space and impairs gas exchange. Surfactant does not cause this condition, but it can be affected by it.

Choice A: This is incorrect because weight less than the 10th percentile (SGA) means that the infant is smaller than expected for the gestational age, but not necessarily low birth weight. SGA infants may have intrauterine growth restriction due to maternal, placental, or fetal factors, but they may also be constitutionally small. SGA infants are at risk for hypoglycemia, hypothermia, polycythemia, and perinatal asphyxia.

Choice B: This is incorrect because weight greater than the 90th percentile means that the infant is larger than expected for the gestational age, but not necessarily high birth weight. Infants with weight greater than the 90th percentile are called large for gestational age (LGA) or macrosomic. LGA infants may have maternal diabetes, genetic factors, or post-term pregnancy as causes, but they may also be constitutionally large. LGA infants are at risk for birth trauma, shoulder dystocia, hypoglycemia, and respiratory distress.

Choice C: This is incorrect because weight between the 10th and 90th percentile means that the infant is appropriate for the gestational age (AGA), but not necessarily normal birth weight. AGA infants have a weight that matches their gestational age and are considered healthy and well-nourished. However, some AGA infants may have low or high birth weight depending on their gestational age at birth.

Choice D: This is the correct answer because low birth weight (LBW) is defined as a weight of 2500g or less at birth, regardless of the gestational age. LBW infants may be preterm (born before 37 weeks of gestation), term (born between 37 and 42 weeks of gestation), or post-term (born after 42 weeks of gestation). LBW infants are at risk for infection, bleeding, jaundice, and neurodevelopmental problems.