How is CPP calculated?

Cerebral Perfusion Pressure (CPP) is calculated using the formula where Mean Arterial Pressure (MAP) is subtracted by Intracranial Pressure (ICP). This method is critical because it determines the pressure gradient driving blood flow to the brain, which is vital for maintaining adequate cerebral perfusion and ensuring that the brain receives enough oxygen and nutrients.

The rationale behind this calculation is that CPP reflects the net pressure available for perfusing the brain tissue. When the ICP is elevated, it can compress cerebral blood vessels, thereby reducing blood flow to the brain. Thus, it is essential to assess how much pressure is available for cerebral perfusion after accounting for the pressure exerted by the skull contents.

The other methods mentioned in the options would not yield a meaningful value for cerebral perfusion. For instance, adding ICP to MAP or subtracting MAP from ICP does not reflect the actual perfusion pressure necessary for cerebral health. Similarly, merely adding Diastolic Blood Pressure (DBP) to MAP lacks relevance to cerebral perfusion analysis. Therefore, the formula correctly reflects the critical balance needed to assess adequate cerebral blood flow.