In cerebral ischaemia, microglia, resident brain macrophages become activated and release detrimental neurotoxic mediators like proinflammtory cytokines, superoxide, nitric oxide (NO), TNF-[alpha] and proteases (42-44).
Other proteases that play a leading role in disruption of blood brain barrier are matrix metalloproteases which contribute to secondary brain damage in cerebral ischaemia (49).
Design of ESPRIT: an international randomized trial for secondary prevention after non-disabling cerebral ischaemia
of arterial origin.
When autoregulation is impaired, increased blood pressure may lead to increased cerebral blood volume (and ICP) and vasogenic oedema, while decreased blood pressure may lead to cerebral ischaemia at unpredictable levels of cerebral perfusion pressure (CPP).
Patients may develop cerebral ischaemia, vasospasm, or cerebral hyperaemia, each of which has unique implications for brain metabolism and the management of ICP.
As MAP continues to decrease, CBF is also reduced, predisposing patients to cerebral ischaemia.
In a similar manner, transcranial Doppler is an effective bedside tool that has been used as an intraoperative monitor of cerebral ischaemia, particularly in the setting of carotid surgery (36).
While it is now recommended in the Surviving Sepsis Campaign Guidelines to maintain the MAP higher than 65 mmHg in order to avoid tissue hypoperfusion, it appears essential when PRES is suspected in relation to sepsis, to increase mean arterial pressure up to at least 105 mmHg to prevent cerebral ischaemia
We report a case of a one-year-old female who had a sudden decrease in bispectral index (BIS) during emergence from anaesthesia, which may have been due to global cerebral ischaemia.
Unusually low BIS values have been previously reported during episodes of cerebral ischaemia (1, 2).
Although a patent foramen ovale is common in healthy individuals, it is most unusual for cerebral ischaemia to be caused by paradoxical embolism from the right to the left side of the heart.
A haematological disorder may also exacerbate any ischaemia caused by co-existent thromboembolism or any other cause of cerebral ischaemia.