Which one of the following is true of hyaline membrane disease of the newborn –
**Core Concept**
Hyaline membrane disease (HMD) of the newborn, also known as respiratory distress syndrome (RDS), is a condition characterized by the inability of the lungs to expand and exchange gases due to a deficiency of surfactant. Surfactant is a complex mixture of phospholipids and proteins that reduces surface tension in the alveoli, allowing them to expand and re-expand during breathing.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of HMD. The condition occurs in premature infants due to a deficiency of surfactant, which is produced by type II pneumocytes in the lungs. Surfactant reduces the surface tension in the alveoli, allowing them to expand and re-expand during breathing. In the absence of sufficient surfactant, the alveoli collapse, leading to respiratory distress. This is why surfactant replacement therapy is often used to treat HMD in premature infants.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because HMD is not caused by an excess of surfactant. The condition occurs due to a deficiency of surfactant.
* **Option B:** This option is incorrect because HMD is not caused by an obstruction in the airways. The condition occurs due to the inability of the lungs to expand and exchange gases.
* **Option C:** This option is incorrect because HMD is not caused by an infection. The condition is a congenital disorder that occurs due to a deficiency of surfactant.
**Clinical Pearl / High-Yield Fact**
Premature infants with HMD often require mechanical ventilation and surfactant replacement therapy to improve lung function and gas exchange. It is essential to recognize the clinical signs of HMD, such as tachypnea, grunting, and nasal flaring, to provide timely intervention and improve outcomes.
**Correct Answer:** D.