A pneumothorax, often called a collapsed lung, is a condition affecting newborns, frequently managed in neonatal intensive care units (NICUs). It represents an abnormal collection of air inside the chest cavity but outside the lung itself. This condition requires careful monitoring and sometimes intervention to ensure the newborn can breathe effectively.
Defining Neonatal Pneumothorax
A pneumothorax is the presence of air in the pleural space, the area between the lung’s surface and the inner wall of the chest. This air accumulates when tiny air sacs, called alveoli, rupture, allowing air to leak out. As air collects in the pleural space, it exerts pressure on the lung, causing it to partially or completely collapse. This condition occurs in up to 1–2% of full-term newborns, with higher rates in sick infants.
The severity depends on the volume of air leaked and the resulting pressure on the lung and heart. A simple pneumothorax involves a small air leak that may cause minimal or no symptoms. If air continues to build up without an exit, it creates a one-way valve effect, leading to a tension pneumothorax. This is an emergency where pressure can shift the heart and major blood vessels, impairing lung and heart function.
Why Pneumothorax Occurs in Newborns
The underlying cause of neonatal pneumothorax is the rupture of alveoli, which are delicate structures vulnerable in newborns. During the transition from fluid-filled lungs in the womb to air-filled lungs after birth, a significant pressure change occurs. This initial high-pressure demand to expand previously uninflated lungs can cause a spontaneous air leak, even in healthy full-term infants.
The risk increases when the newborn has an underlying lung disease that makes the tissues stiff or less compliant. Respiratory Distress Syndrome (RDS), common in premature babies, is a factor because their lungs lack sufficient surfactant, which helps the alveoli stay open. Meconium aspiration syndrome, where the baby inhales its first stool, can also cause airway obstruction and uneven air trapping, leading to alveolar overexpansion and rupture.
A mechanical risk factor is the use of positive pressure ventilation, such as Continuous Positive Airway Pressure (CPAP) or mechanical ventilators. While these devices are life-saving, the forced air pressure can exceed the tolerance of the fragile alveolar walls. Factors like prolonged inspiratory time, high mean airway pressure, and poor synchronization further contribute to the risk of an air leak.
Identifying Signs and Confirming the Diagnosis
The earliest signs of a pneumothorax are often difficulty breathing, though small air leaks may be asymptomatic. The infant may breathe rapidly (tachypnea) or demonstrate labored breathing. A newborn might emit a grunting sound when breathing out, which is the body’s attempt to keep the airways open.
Visible indicators include flaring of the nostrils and the use of accessory muscles, seen as retractions or pulling in of the skin between the ribs or below the breastbone with each breath. If the air accumulation is large, the baby may develop cyanosis (a bluish tint to the skin or lips) due to low oxygen levels. In severe cases, the affected side of the chest might appear larger or show diminished movement compared to the unaffected side.
Physicians suspect a pneumothorax when they listen to the chest and hear diminished or absent breath sounds on one side. A quick, bedside diagnostic method is transillumination, where a fiber-optic light is placed against the baby’s chest in a darkened room. Air in the pleural space scatters the light, causing the affected side to glow more brightly. The definitive diagnosis is confirmed with a chest X-ray, which clearly visualizes the pocket of air and the extent of the lung collapse.
Medical Management and Expected Recovery
The treatment strategy is determined by the size of the air leak and the severity of the symptoms. For small, asymptomatic pneumothoraces, especially in full-term infants without underlying respiratory issues, the air may be reabsorbed by the body over several days. Conservative management involves close observation and sometimes supplemental oxygen to assist the process.
If the pneumothorax is large or causing respiratory distress, the air must be actively removed to allow the lung to re-expand. An immediate, temporary measure for a tension pneumothorax is needle aspiration (thoracentesis), where a small needle is inserted to quickly draw out the trapped air. For persistent or larger air leaks, a chest tube (thoracostomy) is placed between the ribs and connected to a drainage system until the lung heals and the air leak stops.
The prognosis for newborns who develop a pneumothorax is generally favorable, especially for term infants without other major health issues. Most infants recover completely, focusing on managing the acute complication and treating any underlying lung disease. While mortality rates are higher in premature or very low birth weight infants requiring mechanical ventilation, the majority successfully recover and are discharged.