Gravitational Ischemia in the Brain—May Contribute to Delirium and Mortality in the Intensive Care Unit

Highlights

Gravitational ischemia in the brain results from the mass effect of one part of the brain upon another in a gravitational field

The finding that hypoactive delirium was more associated with mortality was consistent with hypoactive patients spending more time in a single body position

Decreased arterial CO₂ in the brain causes vasoconstriction, which reduces blood flow and worsens ischemia in medullary autonomic nuclei

Brainstem focal ischemia may result in the initiation of intense autonomic discharges, which can occasionally be fatal

Abnormal neural discharge to the heart via dorsal motor nucleus of vagus nerve would result in arrhythmias and sudden death