Cerebral Perfusion Pressure - Definitions - By Intracranial Pressure

By Intracranial Pressure

An alternative definition of CPP is:

where:

MAP is mean arterial pressure

ICP is intracranial pressure

This definition may be more appropriate if considering the circulatory system in the brain as a Starling resistor, where an external pressure (in this case, the intracranial pressure) causes decreased blood flow through the vessels. In this sense, more specifically, the cerebral perfusion pressure can be defined as either:

(if ICP is higher than JVP)

orL

(if JVP is higher than ICP).

Physiologically, increased intracranial pressure (ICP) causes decreased blood perfusion of brain cells by mainly two mechanisms:

• Increased ICP constitutes an increased interstitial hydrostatic pressure that, in turn, causes a decreased driving force for capillary filtration from intracerebral blood vessels.
• Increased ICP compresses cerebral arteries, causing increased cerebrovascular resistance (CVR).