Neuroanesthesia Exam 1 Study Guide

Neuroanesthesia

• Circulatory Steal Phenomena: Increase in cerebral blood flow (CBF) in normal tissue rather than ischemic tissue, seen with vasodilators (VA's).
• Luxury Perfusion: CBF exceeds cerebral metabolic rate of oxygen (CMRO2), also seen with VA's.
• Robin Hood Effect: "Reverse steal" phenomenon, where blood flow is redistributed from "rich" areas to ischemic areas, seen with barbiturates.
• "Triple H" Therapy: Primary treatment for ischemic neurologic deficits caused by cerebral vasospasm, consisting of hypertension, hypervolemia, and hemodilution.
• Trigeminal Cardiac Reflex: Massive parasympathetic outflow (bradycardia) seen with opening and closing of dura.
• Artery of Adamkiewicz: Largest segmental medullary artery, supplies anterior and posterior portions of the spinal cord (lower 2/3, lumbosacral region, T11-L2).
• Neurovascular Coupling: Cerebral metabolic rate (CMR) changes affect proportional change in CBF.
• Intracranial Hypertension: Intracranial pressure (ICP) increases, resulting in reduced cerebral perfusion pressure (CPP) and oxygen delivery, leading to cerebral ischemia.
• Monro-Kellie Doctrine: Increases in volume of one intracranial component are compensated by decreases in another component.

Blood-Brain Barrier (BBB) and Blood-CSF Barrier

• BBB: Consists of tight junctions in endothelium, lipid bilayer, and astrocytes, which aid in maintenance.
• CSF: Cushions and buoys the brain, and serves as an excretory pathway.
• Blood-CSF Barrier: Free movement of water and lipophilic substances, but selective transport of ions, glucose, and amino acids.

Cerebral Protection

• Aims: Limiting or reducing ischemic injury via physiologic and pharmacologic techniques.
• Hypothermia: Gold standard among protective techniques, with a 5% change in CMR for every 1°C change in temperature.
• Glucose: Normalization of glucose recommended during cerebral ischemia, as excessive glucose availability can be detrimental.

Blood Distribution to Cerebral Cortex

• Venous Drainage: All venous blood ultimately drains via the internal jugular (IJ) vein.
• Arterial Supply: Anterior and posterior supply, which converge at the circle of Willis.

Anesthetic Considerations

• Alzheimer's: Avoid succinylcholine, avoid anticholinergics, and avoid GETA, as it tends to exacerbate symptoms.
• Parkinson's: Continue Parkinson's medications, avoid butyrophenones and dopamine antagonists, and ensure adequate reversal of neuromuscular blockade.
• Eaton-Lambert: Patients are sensitive to both succinylcholine and non-depolarizing neuromuscular blockers, and require increased dosages of reversal agents.

Miscellaneous Equipment

• Mapleson Systems: Breathing tubing, fresh gas inlet, adjustable pressure-limiting valves (APL)/expiratory valve, and reservoir bag.
• Neuromonitoring: EEG, SSEP, MEP, and BAEP.

Neuromonitoring Pharmacology

• Volatile Anesthetics (VA's): Produce progressive slowing of EEG until burst suppression.
• Intravenous Anesthetics: Ketamine, dexmedetomidine, and opioids affect EEG differently.

Cardiac Implantable Electronic Devices (CIEDs)

• Pacemaker Coding: Position 1-4, which indicate the chamber paced, sensed, response to sensing, and rate modulation, respectively.
• Rate Modulation: Increases supply based on patient demand/activity.
• Magnets: Affect pacemaker and ICD function.

Infection Control

• Transmission-Based Precautions: Contact, droplet, and airborne precautions, with corresponding personal protective equipment (PPE).
• Chlorhexidine vs Povidone-Iodine: Chlorhexidine is preferred for skin preparation in invasive procedures, while povidone-iodine is preferred for neuraxial procedures.

Enhanced Recovery After Surgery (ERAS)

• Surgical Stress Response: Neuroendocrine-metabolic, inflammatory-immune, and catabolic responses to surgical trauma.
• Components of ERAS Protocol: Preoperative, intraoperative, and postoperative components, including education, optimization, medication management, and multimodal analgesia.