Increased Intracranial Pressure (anatomy and monitoring)

Near Skull

Dura Mater

Deeper

Subarachnoid Space

Ventricles

Three components of ICP

Brain tissue (80%)

Blood (10%)

CSF (10%)

The ability of the body to compensate by adjusting the levels of the three components

Intracranial COMPLIANCE (we want equilibrium… when others rise others must accommodate by decreasing)

Skull

Fixed Rigid Immovable “Box”

Limited Space

“Apartment”

What can occur when there is a loss of compliance?

Cerebral Herniation Sydrome

What happens during cerebral herniation syndrome

Brain tissue is displaced → brainstem compressed → BRAIN DEATH

Risk factors for ICP

Brain Bleed (Hemorrhage)

Hematoma (Above/Below Dura Mater)

Hydrocephalus (High CSF)

Encephalitis/Meningitis (Infection)

Tumor (takes up space)

TBI

What is the gold standard for ICP monitoring?

Intraventricular Catheter

Where is the intraventricular catheter placed?

In the VENTRICAL (lateral) of brain

What are the benefits of an intraventricular catheter?

It can monitor and DRAIN CSF (measure CSF output)

• other methods cannot drain

A GCS score of ____ or less requires an ICP monitor to be placed

8 

8 or less is indicative of SEVERE neurological issues

Normal Glasgow Coma Scale

15

Normal ICP

0-15 mmHg

Normal Cerebral Perfusion Pressure (CPP)

generally maintained above 60 mmHg

Equation for CPP

MAP - ICP = CPP

Measuring scale for external ventricular drains

mmHg

cm H2O

How can over drainage be prevented?

Maintain proper leveling of the drainage system (level at the external auditory meatus)

Proper adjustment of the drainage burette at the ordered level ABOVE the external auditory meatus

How should the patient be positioned?

Semi fowlers: 30-45 degrees

Patients head midline

Avoid sharp Hip flexion

Why should the patient’s head by midline?

Facilitate drainage of blood from JUGULAR venous system (decrease ICP)

Why should the patient avoid sharp hip flexion?

Ensures that large veins in the abdomen are not compressed → decreasing venous return

What can happen if the patient is positioned TOO HIGH?

False LOW ICP

the pressure reading will be falsely low, leading to a failure to detect and treat high ICP

What can happen if the Patient is positioned TOO LOW?

False HIGH ICP

A falsely high reading can lead to unnecessary interventions to lower ICP, such as administering medications or draining cerebrospinal fluid (CSF), which puts the patient at risk.