Neurosurgery in the sitting position offers advantages for certain operations. However, the approach is associated with potential complications, in particular venous
air embolism. As the venous pressure at
wound level is usually negative, air can be entrained. This air may follow any of four pathways. Most commonly it passes through the right heart into the pulmonary circulation, diffuses through the alveolar-capillary membrane and appears in expelled gas. It may pass through a pulmonary-systemic shunt such as a probe
patent foramen ovale (paradoxical
air embolism); it may collect at the superior vena cava-right atrial junction. Rarely it may traverse through lung capillaries into the systemic circulation. Many monitors, such as the precordial Doppler; capnography, pulmonary artery
catheter; transoesophageal echocardiography are useful for venous
air embolism detection, with transoesophageal echocardiography being today's gold standard. Various manoeuvres, including neck compression and volume loading, are also useful in reducing the incidence of venous
air embolism. Volume loading, in particular; is very helpful as it reduces the risk of
hypotension. Other particular concerns to the anaesthetist are
airway management, avoidance of
pressure injuries, and the risk of
pneumocephalus, oral
trauma, and
quadriplegia. Newer anaesthetic agents have made the choice of anaesthetic technique easier. An appreciation of the implications of neurosurgery in the sitting position can make the procedure safer