Shedding (infrared) light on the septic brain.

The brain in sepsis Intensive care clinicians will be familiar with the acute brain syndrome observed in patients with sepsis, variously described as “septic encephalopathy” or “sepsis-associated brain dysfunction”.1 Less well appreciated are the long-term morbidity and mortality associated with this condition. Enduring, newonset, moderate-to-severe cognitive impairment is seen in at least 10% of survivors of severe sepsis, with a corresponding increase in new, significant, functional limitations.2 A variety of pathophysiological processes may contribute to brain injury in sepsis. These include the direct effects of inflammation, oedema and cellular dysfunction on the brain — the “neuro-inflammatory response” — as well as the indirect effects of systemic hypotension, hypoxaemia and metabolic derangement.3 The net result includes microglial activation, disruption of the blood–brain barrier, deficit in cholinergic function and ultimately neuronal apoptosis.4