Cerebral blood flow (CBF) is the amount of blood supplied to the brain tissue in a given time.

An optimal CBF is essential to provide adequate oxygen to the brain tissue

The normal CBF value is ~50ml/100g/min or 700 ml/min, accounting for ~14 % of the cardiac output.

Within the limits of systemic mean arterial pressure (MAP), the brain alters the cerebral vascular resistance (CVR) to keep the CBF constant.

Formula used:

The CBF is most commonly calculated using the Kety-Schmidt technique

• Cerebral Blood Flow (CBF) = (MAP - ICP)/CVR
• MAP (Mean art press)= DBP+[1/3(SBP-DBP)]

Data the user will need:

• Systolic blood pressure (SBP); units are mmHg
• Diastolic blood pressure (DBP); units are mmHg
• Intracranial pressure (ICP); units are mmHg
• Cerebral vascular resistance (CVR); units are dynes = mmHg/mL/min

Abbreviations used:

• CBF = Cerebral blood flow
• CVR = Cerebral vascular resistance
• DBP = Diastolic blood pressure
• ICP = Intracranial pressure
• MAP = Mean arterial pressure
• SBP = Systolic blood pressure

Interpretation:

User need to enter the above mentioned values, which are used in the formulas given below

• CBF = (MAP - ICP)/CVR
• MAP = DBP+[1/3(SBP-DBP)]

References:

Anaesthesia UK. Cerebral Blood Flow. http://www.anaesthesiauk.com/article.aspx?articleid=100754. Updated January 16, 2007. Last accessed April 16, 2013.