A newborn developed respiratory distress. Which of the following ors Respiratory distress syndrome?
**Core Concept**
Respiratory distress syndrome (RDS) in newborns is primarily caused by a deficiency of pulmonary surfactant. Surfactant is a complex mixture of phospholipids and proteins that reduces surface tension within the alveoli, facilitating lung expansion and gas exchange during breathing.
**Why the Correct Answer is Right**
Surfactant deficiency leads to increased surface tension, causing alveolar collapse and atelectasis. This results in the characteristic findings of RDS, including tachypnea, grunting, and difficulty expanding the lungs. Type II pneumocytes produce surfactant in the fetal lung, but the process is immature at birth. Premature infants are particularly susceptible to surfactant deficiency due to their underdeveloped lungs. Surfactant therapy is a common treatment for RDS in preterm infants.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the pathophysiology of RDS. While cardiac issues can cause respiratory distress, they are not the primary cause of RDS.
**Option B:** Hypoxia can cause respiratory distress, but it is not the primary cause of RDS. RDS is characterized by a specific deficiency of surfactant, not a lack of oxygen.
**Option C:** Meconium aspiration syndrome (MAS) is a different condition that can cause respiratory distress in newborns. While it can present with similar symptoms, MAS is caused by the inhalation of meconium, not surfactant deficiency.
**Clinical Pearl / High-Yield Fact**
Premature infants with RDS often require surfactant replacement therapy to improve lung function and reduce the risk of mortality.
**Correct Answer:** C. Meconium aspiration syndrome