Raised intrathoracic pressure refers to an increase in pressure within the thoracic cavity, which can occur due to conditions such as tension pneumothorax or severe asthma exacerbations. This elevation can compromise venous return to the heart, leading to decreased cardiac output and potential cardiovascular collapse. Clinically, it is crucial to recognise and address raised intrathoracic pressure promptly, as it can result in life-threatening complications like respiratory failure or shock.