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Clinical Applications - Brain Death

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Brain death is an irreversible end of brain activity due to total cerebral circulatory arrest. The cerebral blood flow circulation is enabled thanks to the existence of cerebral perfusion pressure (CPP), the CPP is a function of the mean arterial blood pressure (MABP) and the intracranial pressure (ICP)

CPP=MABP-ICP

Usually brain death is a consequence of increased intracranial pressure (ICP), elevated ICP can be caused due to various reasons such as: metabolic, toxic, traumatic head injury, infectious, neoplastic and idiopathic (tumors). When the ICP reaches a level which is equal or higher than the mean arterial blood pressure (MABP) the blood flow circulation in the brain will arrest and the brain will die.

Determination of brain death becomes very important in modern medicine due to its role for saving lives through organ transplantations. Today in most countries, the national ministry of health determines a specific protocol for diagnosis and determination of brain death, in all protocols there will be the obligation to use a medical device. Transcranial Doppler (TCD) is one of the most common medical devices to be used for diagnosis and support decision tool for brain death due to its unique effect on cerebral blood flow pattern.

In TCDs' brain death diagnosis examination the operator is required to examine the anterior and posterior cerebral circulation thoroughly, when each blood vessel is examined for at least 3 minutes and the whole examination length should be at least half an hour. If a complete circulatory arrest is existing we will find patterns of flow cessation, oscillating patterns with negative flow in diastole, and short systolic spikes (<50cm/sec).

to and fro

“To and Fro” Waveform
Pattern- Oscillating patterns with negative flow in diastole when ICP becomes
higher than diastolic ABP (irreversible)

 

short systolic spikes

Short systolic spikes

The Digi-Lite TCD is used as a diagnostic tool for complete cerebral circulatory arrest in many countries around the world thanks to its very high sensitivity (97%) and specificity (100%), its state of the art advanced summary screen gives the physician the complete data of the anterior and posterior cerebral circulation. The TCD can be used at the patients' bedside, it is repeatable, cost effective, non-invasive, no pharmacological effect on the test, and no need to use contrast agents that can harm the kidneys.

Complete cerebral circulatory arrest Summary screen

Complete cerebral circulatory arrest Summary screen