May 2026 - Tension Pneumothorax in a Preterm Infant: Integrating Lung POCUS and Serial Radiography

Case Summary

This case highlights the rapid deterioration of a 26 week, 800 g preterm infant with evolving respiratory failure secondary to a large right-sided tension pneumothorax. The case demonstrates how bedside lung ultrasound complemented serial chest radiography to rapidly confirm the diagnosis, assess severity, and guide urgent procedural management in a critically ill neonate.

Clinical Situation

The infant, born at 26 weeks’ gestation with a birth weight of 800 g, was initially intubated on day 1 of life for surfactant-deficient respiratory distress syndrome. Over the following hours, the infant developed escalating oxygen requirements despite ventilatory adjustments and administration of a second dose of surfactant following repositioning of a deep endotracheal tube identified on chest radiography. Bedside lung POCUS was performed during an episode of acute decompensation while the infant was receiving 100% FiO2 with severe pre- and post-ductal hypoxemia. Following surfactant administration, there was a transient improvement in oxygen saturations (from approximately 70% to 85%), but this was rapidly followed by worsening respiratory failure and hemodynamic instability (dropping blood pressure). Lung ultrasound of the right hemithorax demonstrated absent lung sliding with a barcode/stratosphere sign on M-mode, confirming pneumothorax. In contrast, the contralateral lung demonstrated preserved lung sliding with a normal seashore sign, although the left lung fields showed a heterogeneous score 2–3 pattern characterized by coalescent B-lines and scattered subpleural air bronchograms consistent with evolving surfactant-deficient lung disease. These findings rapidly supported the diagnosis of a clinically significant right-sided air leak syndrome. Chest radiography confirmed a large right pneumothorax with marked hyperexpansion of the right hemithorax and compression of the contralateral lung. An urgent needle decompression was performed with evacuation of 14 mL of air, resulting in transient improvement. However, repeat POCUS and chest radiography demonstrated rapid re-accumulation of the pneumothorax, prompting insertion of a right-sided chest tube under sterile conditions. Following drainage, the infant demonstrated immediate clinical improvement with rapid reduction in FiO2 requirements from 100% to 28%, improved blood pressure, better perfusion, and recovery of urine output. Repeat lung ultrasound demonstrated restoration of lung sliding without residual pneumothorax, while post-drainage chest radiography confirmed re-expansion of the right lung and appropriate chest tube position. This case illustrates several important teaching points in neonatal POCUS and air leak physiology. First, lung ultrasound can rapidly confirm pneumothorax at the bedside in unstable neonates and may identify clinically significant air leaks before repeat radiography is obtained. Second, interpretation of lung findings must always be integrated with airway positioning and ventilator mechanics, particularly in extremely preterm infants where small endotracheal tube position changes may substantially alter regional ventilation and predispose to asymmetric overdistension. Finally, serial multimodal assessment integrating clinical examination, radiography, and bedside ultrasound provides valuable physiologic information that can accelerate diagnosis and guide timely intervention in critically ill neonates.

Post-Drainage POCUS & X-ray:

A follow-up POCUS demonstrated resolution of the pneumothorax, with the return of lung sliding (only a small physiological sliver remained at the diaphragmatic level on the right side). Repeat blood gases and X-rays confirmed the chest tube and ETT were in good position, with persistent but manageable mild hyperinflation on HFJV.

Outcome

Following the chest tube insertion, the infant exhibited immediate clinical recovery:

• Respiratory: FiO2 was rapidly weaned from 100% down to 50%, and later to 28-30%. The right chest tube was placed on suction and stopped bubbling a few minutes post-insertion.

• Hemodynamic: Blood pressures normalized

POCUS Pearls: Neonatal Pneumothorax

1. Speed to Diagnosis: In a rapidly deteriorating neonate with cardiorespiratory compromise, lung POCUS can facilitate the rapid bedside detection of an underlying pneumothorax. However, ultrasound alone may not always provide full appreciation of the overall size and extension of the pneumothorax. A systematic examination of multiple lung regions and segments may help estimate the distribution and extent of pleural air. When clinical circumstances permit, chest radiography can further support the diagnosis, assess the degree of lung collapse and mediastinal shift, and help guide procedural planning while preparing for needle decompression or chest tube drainage depending on the severity of the infant’s clinical condition.

2. The Barcode Sign: On M-mode, the normal "Seashore sign" (granular appearance below the pleural line indicating motion) is replaced by the "Barcode" or "Stratosphere sign" (parallel horizontal lines throughout), suggesting the absence of pleural sliding.

3. A-Lines vs. B-Lines: In a pneumothorax, air fills the pleural space, reflecting all ultrasound waves. This completely obscures any B-lines (which require a dense lung/pleural interface) and exclusively displays A-lines.

4. It is important to remember that even a single B-line essentially excludes a pneumothorax at that location. This highlights why systematic use of M-mode is important to reduce diagnostic uncertainty. In practice, the diagnosis of pneumothorax should not rely on a single isolated finding, but rather on the integration of multiple concordant signs: absence of B-lines, absence of pleural line shimmering/sliding, and the presence of a barcode (stratosphere) sign on M-mode.

Conclusion

In the setting of sudden respiratory and hemodynamic deterioration, lung POCUS enables rapid bedside diagnosis of pneumothorax, facilitating timely recognition and immediate intervention. The earliest B-mode finding is the loss of the normal shimmering movement between the visceral and parietal pleura, reflecting absence of lung sliding. On M-mode, the normal “seashore sign,” characterized by a granular appearance below the pleural line generated by lung motion, is replaced by parallel horizontal lines extending throughout the field depth — the classic “barcode” or “stratosphere” sign — confirming absent pleural sliding. Air within the pleural space strongly reflects ultrasound waves, producing repetitive horizontal A-lines that are equidistant from one another. As a result, pneumothorax classically demonstrates a pattern dominated by reverberating A-lines. In contrast, the presence of even a single B-line effectively excludes pneumothorax at that exact intercostal space, as B-lines require contact between the visceral and parietal pleura to generate the tissue–air interface necessary for their formation. Identification of the transition point between normal lung sliding and absent sliding — the “lung point” — may further help estimate the extent of the pneumothorax. A tension pneumothorax is not solely a respiratory event but also a major hemodynamic emergency. Progressive elevation in intrathoracic pressure impairs systemic venous return, reduces right ventricular preload, and may precipitate secondary left ventricular dysfunction with systemic hypotension and poor end-organ perfusion. Integrating a focused cardiac POCUS assessment alongside the lung examination may therefore provide important physiologic insight into the severity of cardiovascular compromise and help assess recovery following drainage. Importantly, POCUS also provides real-time procedural feedback. Following needle decompression or chest tube insertion, repeat lung ultrasound should demonstrate restoration of lung sliding and reappearance of the normal seashore sign on M-mode, confirming successful evacuation of pleural air and lung re-expansion.