Inhalational Anesthetic Agents

Desflurane, CF₃-CFH-O-CF₂H

Physical Properties

• vapor pressure = 681 mmHg at 20 degrees C so
• boils at room temperature at high altitudes (eg, Denver, Colorado), and
• requires special vaporizer
• low solubility permits rapid changes in p_A and thus p_Brain
• pungent and irritating to the airway

Organ System Effects

• similar to isoflurane (but does NOT increase coronary artery blood flow)
• cardiac output no more than slightly depressed at 1-2 MAC
• rapid increases in p_a may -> pronounced tachycardia and hypertension

• fast, shallow breathing with incresased p_aCO₂
• airway irritation
  • salivation
  • breath-holding
  • coughing
  • laryngospasm

• general anesthesia, MAC = 6.0
• cerebral vasodilator, increases CBF and ICP
• marked decrease in CMRO₂ tends to cause compensatory vasoconstriction
• EEG effects similar to isoflurane

Biotransformation and Toxicity

• minimal metabolism in vivo
• degraded (more than other agents) to potentially harmful levels of carbon monoxide by desiccated carbon dioxide absorbent
  • especially by barium hydroxide lime, but also by sodium and potassium hydroxide
  • use of calcium hydroxide minimizes this degradation problem

Contraindications

• malignant hyperthermia susceptibility
• hypovolemia
• intracranial hypertension

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