Hypothesis

THE LUXURY-PERFUSION SYNDROME AND ITS POSSIBLE RELATION TO ACUTE METABOLIC ACIDOSIS LOCALISED WITHIN THE BRAIN

TCD is a portable, repeatable, non-invasive technique in the bedside assessment and monitoring of cerebral blood flow with high temporal resolution. Since its introduction into neurological practice in the 1980s, transcranial Doppler ultrasonography has become an indispensable method of non-invasive examination of the cerebral circulation and an indispensable tool in emergency neurology. In the current review, we presented the principles and technical nuances of the use of TCD, as well as the indispensability of TCD in the treatment of patients with traumatic brain injury. We have studied the usefulness of this tool for assessing hypoperfusion, the development of cerebral vasospasm, non-invasive determination of intracranial pressure (ICP), and predicting the patient’s outcome at TBI, as well as studying the state of cerebral autoregulation.

Serum levels of carbon dioxide (CO₂) closely regulate cerebral blood flow (CBF) and actively participate in different aspects of brain physiology such as hemodynamics, oxygenation, and metabolism. Fluctuations in the partial pressure of arterial CO₂ (PaCO₂) modify the aforementioned variables, and at the same time influence physiologic parameters in organs such as the lungs, heart, kidneys, and the gastrointestinal tract. In general, during acute brain injury (ABI), maintaining normal PaCO₂ is the target to be achieved. Both hypercapnia and hypocapnia may comprise secondary insults and should be avoided during ABI. The risks of hypocapnia mostly outweigh the potential benefits. Therefore, its therapeutic applicability is limited to transient and second-stage control of intracranial hypertension. On the other hand, inducing hypercapnia could be beneficial when certain specific situations require increasing CBF. The evidence supporting this claim is very weak. This review attempts providing an update on the physiology of CO₂, its risks, benefits, and potential utility in the neurocritical care setting.