Pneumothorax What is a bleb and how is this different from a bulla? Spontaneous primary pneumothoraces often arise from the rupture of a subpleural bleb. These are small pockets of air less than 1-2 cm in diameter and if they rupture, the air from the bleb can escape into the pleural space, giving rise to a pneumothorax. Blebs are more common in young, thin patients and occur as a result of alveolar sacs rupturing if their elastic membrane is overstretched. Blebs differ from bullae, with the latter being larger and associated with emphysema. Blebs are smaller and seen in healthy individuals. Can you explain the different types of pneumothorax? Pneumothorax describes the presence of air in the pleural space. These can be divided into spontaneous (primary and secondary), and traumatic pneumothoraces. A spontaneous pneumothorax occurs in the absence of trauma and is classed as primary if the patient has no underlying lung disease. A secondary spontaneous pneumothorax according to the BTS is defined as a pneumothorax which occurs in the presence of underlying lung disease or if the patient is above 50 with a smoking history. A traumatic pneumothorax can lead to a tension pneumothorax or a simple (non-tension) pneumothorax. What is VATS and talc pleurodesis? In patients with recurrent pneumothoraces, patients may need definitive management to obliterate the pleural space (pleurodesis) to prevent further episodes. Talc is an irritant that is inserted via a chest drain into the pleural space with the subsequent inflammatory reaction causing obliteration of the pleural space. It can also be inserted via VATS. VATS (video-assisted thoracoscopic surgery) describes an endoscopic procedure whereby a small scope can be passed into the thorax and either talc can be inserted to cause pleurodesis, or in some cases a pleurectomy may be performed. Pulmonary Embolism When do you do a V/Q scan over a CTPA scan In pregnancy, CTPA poses a greater risk to the mother compared to a V/Q scan as it is associated with an increased risk of breast cancer. However, the V/Q scan poses a greater risk to the baby, increasing the risk of childhood cancer. The RCOG do not give definitive guidelines and advise following local protocol. Would you commence LMWH whilst starting warfarin? This is referred to as ‘bridging’. The reason it is required is because it takes about 5 days for warfarin to reach the INR range of 2-3. Hence, patients will be subtherapeutic in this timeframe and are therefore given LMWH to ensure they are adequately anticoagulated for the first 5 days. Additionally, in the first few days of starting warfarin, patients are actually prothrombotic as protein C and S, vitamin K dependent anticoagulants, are diminished in relation to the coagulation factors II, VII, IX and X, which have a longer half-life. This shifts patients into a prothrombotic state, further emphasising the need for bridging. In reality, bridging is not always conducted in clinical practice and requires the clinician to determine the risk of bleeding being on 2 anticoagulants in relation to the risk of thromboembolism. Why choose a DOAC over warfarin? DOACs are starting to be used more commonly for VTE in comparison to warfarin. The reason for this is that DOACs do not require the extensive monitoring that warfarin does. .