Being a critical care nurse, it is vital to understand how to recognize if your patient has elevated ICP.  A good understanding of your patient’s vitals and baseline assessment will be essential in monitoring your patient.

Signs of Intracranial Hypertension

Cushing’s Triad

• Wide pulse pressure with an increased systolic blood pressure and decreased diastolic pressure
  • Increased sympathetic tone increases the SBP
• Bradycardia
  • High pressure is detected by the baroreceptors in the carotid arteries and aortic arch, sending messages to the brain stem stimulating the vagus nerve to reduce the heart rate
• Irregular breathing, may progress to apnea
  • High pressure is detected in the brain stem medulla creating an abnormal breathing pattern

Why is Cushing’s Triad bad?

It is signalling brain stem compression. THIS IS VERY BAD, signalling impending brain herniation which is fatal, occurring in seconds to minutes.

Intracranial Pressure (ICP):

• Normal values:
  • 0  – 15 mm Hg
• Treatment is indicated if sustained > 20 – 25 mm Hg

Cerebral Perfusion Pressure (CPP)

• Pressure needed to perfuse the brain
• MAP – ICP = CPP
• Goal = > 60
• Normal CPP: 60 – 80 mm Hg
• Often we target the MAP to be 70 – 100 mm Hg

*** The CPP is more dynamic than we thought  and the mean arterial blood pressure decreases 10 to 15 mm Hg before getting to the brain.

• Use CPPot if technology is available or transcranial doppler (TCD) although TCD is only a snapshot in time

Stay tuned for our last stroke series blog on Management of Intracranial Hypertension coming soon!

References:

Intracranial Pressure Monitoring: Background, Indications, Contraindications

Evaluation and management of elevated intracranial pressure in adults – UpToDate

Management of acute moderate and severe traumatic brain injury in adults – UpToDate

Monro-Kellie 4.0: moving from intracranial pressure to intracranial dynamics | Critical Care | Springer Nature Link