The chapter explores the application of continuous positive airway pressure (CPAP) in pleural thoracentesis to improve patient outcomes. Thoracentesis, a standard procedure to evacuate pleural effusion or pneumothorax, carries risks like re-expansion pulmonary oedema (REPE) and other complications. These complications often result from rapid lung expansion following fluid removal, creating negative intrathoracic pressure. The CPAP’s efficacy in stabilising intrathoracic pressure and minimising adverse effects enhances oxygenation and alveolar recruitment, mitigating the risk of hypoxemia and intrapulmonary shunt. It also regulates sympathetic activity, improving patient comfort and pulmonary function. Clinical evidence suggests CPAP can safely counteract pleural pressure drops. Studies have shown that using CPAP during thoracentesis increases the volume of fluid drained and decreases the risk of REPE. The randomised trials demonstrate that CPAP maintains pleural compliance at low positive pressures and ensures steady lung re-expansion. The findings indicate that CPAP may offer a strategic advantage, particularly for high-risk patients, such as those with extensive effusions or compromised respiratory function. However, further research is needed to establish guidelines and optimise CPAP settings for clinical scenarios.