From the Guidelines
External pressure causing atelectasis primarily comes from conditions that compress the lung tissue from outside, such as pleural effusion, pneumothorax, large tumors, and abdominal distention, which can be managed by addressing the underlying cause and supporting oxygenation, as suggested by experts in the field 1.
Causes of External Pressure
Some of the key causes of external pressure leading to atelectasis include:
- Pleural effusion (fluid accumulation between the lung and chest wall)
- Pneumothorax (air in the pleural space)
- Large tumors in the chest cavity
- Enlarged organs like the heart or liver pushing against the lungs
- Significant chest trauma with rib fractures
- Abdominal distention from ascites, pregnancy, or obesity
- Tight chest bandages or casts
- Prolonged positioning during surgery, especially in obese patients
Mechanism of Atelectasis
These external pressures prevent normal lung expansion during breathing, causing air to be absorbed from the affected alveoli without being replaced, leading to collapse of lung tissue, as explained in the context of mechanical ventilation in ARDS patients 1.
Management and Treatment
Treatment involves addressing the underlying cause of external pressure while supporting oxygenation, and may require procedures to remove fluid, air, or masses compressing the lung, with the goal of improving gas exchange and reducing the risk of ventilator-induced lung injury, as discussed in the management of hemodynamics in ARDS patients 1.
Key Considerations
It is essential to consider the hemodynamic effects of mechanical ventilation, including the impact of positive end-expiratory pressure (PEEP) on pulmonary vascular resistance and the importance of monitoring hemodynamics to optimize perfusion and minimize the risk of ventilator-induced lung injury, as highlighted in recent studies 1.
From the Research
External Pressure and Atelectasis
- External pressure can cause atelectasis, which is the collapse or closure of a lung resulting in reduced or absent gas exchange [(2,3,4,5,6)].
Types of External Pressure
- Continuous positive airway pressure (CPAP) is a type of external pressure that can be used to prevent or treat atelectasis [(2,3)].
- Noninvasive pressure support ventilation (NIPSV) is another type of external pressure that can be used to improve the evolution of atelectasis 2.
- Positive end-expiratory pressure (PEEP) is a type of external pressure that can be applied with a face mask to increase functional residual capacity 5.
- Positive expiratory pressure (PEP) is a type of external pressure that can be used to promote lung expansion 6.