Count to 10 - Anaesthetic Primary Podcast EP39 – Cerebral Blood Flow, ICP & Spinal Cord Perfusion | Anaesthetic Primary Topic | Neurophysiology & Pain | CT10
Jul 19, 2025
The discussion dives into the fascinating world of neurophysiology, focusing on intracranial pressure (ICP) and cerebral blood flow (CBF). Key concepts include the Monro-Kellie Doctrine and how ICP is measured. The host explains Cushing's reflex and emergency management strategies. Listeners will learn about the interplay between CO2, O2, and CBF, as well as how anesthetic drugs influence these dynamics. Spinal cord perfusion is also covered, emphasizing its continuous link to brain physiology, alongside practical insights for exam preparation.
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Monroe‑Kelly Basis Of ICP
- Intracranial pressure (ICP) reflects hydrostatic pressure inside a fixed-volume skull and normally ranges 5–15 mmHg.
- The Monroe-Kelly doctrine states increases in brain, blood, or CSF volume must be compensated or ICP will rise.
Act Before Exponential ICP Rise
- Early compensation for rising ICP uses CSF translocation and vascular adjustments; late compensation fails as ICP approaches ~20 mmHg.
- Act quickly before the exponential ICP rise and decompensation at ~50 mmHg to avoid global ischemia.
Respond Fast To Cushing's Reflex
- When Cushing's reflex appears (hypertension, bradycardia), urgently lower ICP by altering brain volume, CSF, or blood volume.
- Use steroids for tumour edema, EVD for CSF, and mannitol/hypertonic saline for acute management.