From the Research
The Macklin effect is a pathophysiological process where air escapes from ruptured alveoli in the lungs and travels along the bronchovascular sheaths toward the mediastinum, causing pneumomediastinum, and is closely correlated with pneumomediastinum in acutely ill intubated patients with COVID-19 infection, as shown in a recent study 1. The Macklin effect typically occurs when increased alveolar pressure leads to alveolar rupture, allowing air to dissect along the perivascular spaces into the mediastinum. Some key points to consider about the Macklin effect include:
- It is commonly seen in conditions involving barotrauma, such as mechanical ventilation with high pressures, asthma exacerbations, or blunt chest trauma 2.
- It can also occur during activities that involve Valsalva maneuvers like intense coughing, vomiting, or childbirth.
- The escaped air may further dissect into the neck (causing subcutaneous emphysema), the pleural space (causing pneumothorax), or even the retroperitoneum.
- Management typically involves treating the underlying cause, providing supportive care, and monitoring for complications, as most cases of pneumomediastinum from the Macklin effect resolve spontaneously without specific intervention 2. In terms of diagnosis, the Macklin effect can be identified on chest CT scans, and patients with this effect on chest CT scan had a 90% rate of pneumomediastinum, as shown in a study 1. The Macklin effect may be a strong radiographic biomarker for pulmonary barotrauma, most strongly correlating with pneumomediastinum, and future critical care treatment algorithms may include the Macklin sign for clinical decision making and prognostication 1.