Aneurysmal subarachnoid haemorrhage and the anaesthetist.

The anaesthetist may be involved at various stages in the management of subarachnoid haemorrhage (SAH). Thus, familiarity with epidemiological, pathophysiological, diagnostic, and therapeutic issues is as important as detailed knowledge of the optimal intraoperative anaesthetic management. As the prognosis of SAH remains poor, prompt diagnosis and appropriate treatment are essential, because early treatment may improve outcome. It is, therefore, important to rule out SAH as soon as possible in all patients complaining of sudden onset of severe headache lasting for longer than an hour with no alternative explanation. The three main predictors of mortality and dependence are impaired level of consciousness on admission, advanced age, and a large volume of blood on initial cranial computed tomography. The major complications of SAH include re-bleeding, cerebral vasospasm leading to immediate and delayed cerebral ischaemia, hydrocephalus, cardiopulmonary dysfunction, and electrolyte disturbances. Prophylaxis and therapy of cerebral vasospasm include maintenance of cerebral perfusion pressure (CPP) and normovolaemia, administration of nimodipine, triple-H therapy, balloon angioplasty, and intra-arterial papaverine. Occlusion of the aneurysm after SAH is usually attempted surgically ('clipping') or endovascularly by detachable coils ('coiling'). The need for an adequate CPP (for the prevention of cerebral ischaemia and cerebral vasospasm) must be balanced against the need for a low transmural pressure gradient of the aneurysm (for the prevention of rupture of the aneurysm). Effective measures to prevent or attenuate increases in intracranial pressure, brain swelling, and cerebral vasospasm throughout all phases of anaesthesia are prerequisite for optimal outcome.