From the Guidelines
A pneumatocele is a thin-walled, air-filled cyst or cavity that develops within the lung tissue, typically as a complication of pneumonia, trauma, or mechanical ventilation, and is associated with a high morbidity and mortality in immunocompromised patients, such as those with AIDS. The formation of pneumatoceles is often seen in the context of necrotizing alveolitis, where the sub-pleural pulmonary parenchyma is replaced by necrotic tissue and cysts, as described in the context of Pneumocystis carinii pneumonia (PCP) 1. Some key characteristics of pneumatoceles include:
- They can vary in size from a few millimeters to several centimeters
- They may be single or multiple
- They are most commonly seen in children following staphylococcal pneumonia, though they can occur with other infectious agents like Pneumocystis jirovecii in immunocompromised patients
- Most pneumatoceles resolve spontaneously within weeks to months without specific treatment, requiring only monitoring with serial chest imaging 1. However, larger pneumatoceles may cause respiratory distress by compressing surrounding lung tissue or may rupture, leading to pneumothorax, which can be particularly problematic in patients with AIDS-related pneumothorax, who have a higher hospital mortality, a higher incidence of bilateral and recurrent pneumothoraces, and more prolonged air leaks 1. In severe cases where the pneumatocele causes significant symptoms or complications, interventions such as percutaneous drainage or surgical resection might be necessary, especially in immunocompromised patients where the risk of morbidity and mortality is higher 1.
From the Research
Definition and Characteristics of Pneumatocele
- A pneumatocele is an air-filled, thin-walled cavity that develops within the lung parenchyma 2, 3, 4, 5.
- Pneumatoceles are also known as pneumatic cysts in the lung 2.
- They can be gas-filled cysts within the lung parenchyma, resulting from ventilator-induced lung injury and air-leak in premature infants with respiratory distress syndrome 4.
Causes and Associations of Pneumatocele
- Pneumatoceles typically develop as a complication of pneumonia, but they may also result from infections, trauma, or positive pressure ventilation 2, 5.
- They can occur infrequently in neonates and infants, often as a complication of positive pressure ventilation, air leak syndrome, or ventilator-associated pneumonia 3.
- Pneumatoceles are associated with significant mortality, similar to other intrathoracic air-leaks, and are markers for ventilator-induced lung injury 4.
- Post-traumatic pneumatocele and hemato-pneumatocele of the lung can develop after thoracic trauma, with a direct violent impact on the pliable lung wall 6.
Clinical Implications and Treatment of Pneumatocele
- The clinical implications of pneumatoceles can be minimal, with a favorable evolution and restitution of the integrity of the pulmonary parenchyma after several weeks, often without the need for therapeutic intervention 6.
- However, large pneumatoceles may lead to acute cardiorespiratory insufficiency and may require drainage under computerized tomography, fluoroscopic guidance, or bedside ultrasound guidance 3, 5.
- Conservative management with reduction in mean airway pressure can be effective in the resolution of pneumatoceles, and interventional decompression of the pneumatocele is generally not necessary 4.