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Volatile Organic Anesthetic

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Volatile Organic Anesthetic, Volatile Liquid Anesthetic Agent, Halothane, Fluothane, Enflurane, Ethrane ( C0701979), Isoflurane, Forane, Desflurane, Suprane, Sevoflurane, Ultane

  • Indications
  1. General Anesthetic Gas
  • Contraindications
  1. Malignant Hyperthermia Family History or personal history
  • Definitions
  1. Ether
    1. Organic compounds in which two carbon atoms are linked through an oxygen atom (C-O-C)
    2. Diethyl ethers have historically been used as inhaled Anesthetics
  • Background
  1. Newer inhaled Anesthetics (Desflurane, Sevoflurane) are fully fluorinated analogs of Isoflurane
    1. Isoflurane (partially fluorinated) required a longer recovery period (esp. in obese patients) than these newer analogs
    2. These newer agents are also not flammable (contrast with Nitrous Oxide)
  2. Older agents (Halothane, Enflurane) are not in typical modern use in the U.S.
    1. These older agents were associated with a greater degree of myocardial depression and adverse effects
  3. First inhalation Anesthetic was ether
    1. Ether was synthesized in 1540, and was first used for medical Anesthesia in the U.S. in the 1840s
    2. Nitrous Oxide was also used during this time period, first used in 1772
    3. Chaturvedi (2011) Med J Armed Forces India 67(4):306-8 +PMID: 27365835 [PubMed]
  • Mechanism
  1. Ethers with general Anesthetic (Sedative, hypnotic effects) and Skeletal Muscle Relaxant properties
    1. Most inhaled Anesthetics are fluorinated
  2. Inhalational agents are supplied as liquids and are vaporized to gas for inhalation
    1. CNS concentrations are directly related to alveolar concentrations
    2. Minimal alveolar concentration (MAC) reflects level at which 50% of patients will not move with painful stimulus
  3. Blocks release and re-uptake of Neurotransmitters at post-synaptic terminals and decreases conductance
  4. May affect Neuron ion channels and may also activate GABA Receptors
  • Medications
  • Sevoflurane
  1. Minimum Alveolar Concentration: 1.8%
  2. Used in the U.S. since the 1990s and is among the most commonly used inhalational Anesthetics for surgery
  3. Safety
    1. Pregnancy Category C
    2. Unknown safety in Lactation
  • Medications
  • Desflurane
  1. Minimum Alveolar Concentration: 6.0%
  2. Safety
    1. Pregnancy Category B
    2. Considered safe in Lactation
  3. Precautions
    1. Laryngospasm is common (avoid in pediatrics)
    2. Avoid as sole Anesthetic in Coronary Artery Disease
  • Medications
  • Isoflurane
  1. Older agent, replaced by Desflurane and Sevoflurane
  2. Minimum Alveolar Concentration: 1.15%
  3. Safety
    1. Pregnancy Category C
    2. Unknown safety in Lactation
  4. Adverse Effects
    1. Longer recovery period than newer agents (esp. in Obesity)
  • Pharmacokinetics
  1. Isoflurane undergoes minimal metabolism (hence fewer adverse effects than Halothane or Enflurane)
  2. All volatile Anesthetics deposit in fatty tissue
  • Adverse Effects
  1. Cardiovascular
    1. Myocardial Depression, decreased contractility and decreased mean arterial pressure
    2. Decreased Vascular resistance
    3. Myocardial Catecholamine sensitization
  2. Respiratory
    1. Respiratory depression
    2. Bronchodilation
  3. Other Serious Effects
    1. Malignant Hyperthermia (all volatile Anesthetics)
    2. Allergic Hepatotoxicity (Halothane)
    3. Enflurane (Nephrotoxicity)
    4. Diffuse Alveolar Hemorrhage (Sevoflurane)
      1. Ahmed-Khan (2023) Arch Clin Cases 10(1): 29-31 [PubMed]
  • Resources
  1. Desflurane (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=21ba0e18-3dbc-4feb-a3a4-f6470c00910a
  2. Isoflurane (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2dd44148-5818-42f3-8b6e-75000e4fe55a
  3. Sevoflurane (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3dbab949-6ab7-4040-9c81-314e5bb61d41
  • References
  1. Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 56-7
  2. Smith (2023) General Anesthesia for Surgeons, StatPearls, Treasure Island, FL
    1. https://www.ncbi.nlm.nih.gov/books/NBK493199/