#432: Intro to Anesthetic Gases

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If you’re heading into a perioperative clinical rotation or exam, or are transitioning to surgical nursing or PACU nursing, this lesson provides an overview of anesthetic gases.

What are anesthetic gases?

Anesthetic gases (also known as inhaled anesthetics) are substances used to produce anesthesia for surgery. They quickly enter arterial blood via pulmonary circulation, allowing for efficient induction and discontinuation.

How do anesthetic gases work?

Anesthetic gases depress neurotransmission of excitatory paths involving acetylcholine, glutamate, and serotonin within the central nervous system (CNS). They also augment inhibitory signals including chloride and potassium channels. These disruptions induce a state of unconsciousness, immobility and amnesia. Some inhaled anesthetics can also have an analgesic effect.

Two types of anesthetic gases

There are two types of anesthetic gases – volatile and non-volatile.

• Volatile anesthetics have low vapor pressure and a high boiling point. This means they are liquid at room temperature and must be vaporized for administration. The volatile anesthetic gases are halothane, isoflurane, desflurane, and sevoflurane. Notice they all end in “ane.”
• Non-volatile anesthetics have high vapor pressure and a low boiling point. This means they are in gas form at room temperature. Nitrous oxide is a non-volatile anesthetic gas and is used frequently in dentistry as well as a component of general anesthesia.

Key points about anesthetic gases

One thing to know about the volatile anesthetic gases is that they can trigger a condition called malignant hyperthermia. Malignant hyperthermia is a dangerous reaction that leads to a hypermetabolic state. Complications include hyperthermia, hyperkalemia, myoglobinuria, cardiac arrhythmias, acute renal failure, DIC, metabolic acidosis, and death. Nitrous oxide, which is a non-volatile gas, does not trigger this reaction.

Halothane key points

• Highest likelihood of all volatile gases to trigger malignant hyperthermia
• Not to be used in patients with liver dysfunction, reduced ejection fraction or pheochromocytoma
• Can cause fulminant liver necrosis
• Not commonly used

Isoflurane key points

• Pungent odor and can cause bronchospasm or laryngospasm
• Avoided in patients with restrictive airway disease (asthma, COPD)
• Typically used for maintenance (not induction)
• Can cause reflex tachycardia

Desflurane key points

• Similar to isoflurane (above)
• Highest risk for carbon monoxide poisoning due to byproducts of the gas

Sevoflurane key points

• Sweet smelling and suitable for mask induction
• Often used with pediatrics
• Less risk for laryngospasm (but it can still occur)
• Considered the safest volatile gas for patients with asthma
• Byproducts do not create carbon monoxide
• Avoided in patients with renal disease
• The most commonly used inhaled anesthetic

Nitrous oxide key points

• Can increase ICP
• The least potent of inhaled anesthetics, so it must be combined with other agents
• Avoided in pneumothorax, bowel obstruction, middle ear surgery (it expands air space)
• Risk of diffusion hypoxia when discontinued, so maintain patient on 100% FiO2 for a few minutes

Anesthetic gas adverse effects

Adverse effects of anesthetic gases include postoperative nausea and vomiting (PONV), bronchospasm, laryngospasm, and hypotension. These are the things you’re watching for in the post anesthesia period:

• PONV – Prophylactic antiemetics should be administered such as ondansetron (Zofran), metoclopramide (Reglan), dexamethasone, scopolamine patch, and aprepitant (Emend).
• Bronchospasm and laryngospasm – Sevoflurane and nitrous oxide are the least likely to cause airway irritation.
• Hypotension – Volatile anesthetics reduce SVR, leading to hypotension. The effect is more profound in hypovolemic patients.

Anesthetic gas complications

Complications of anesthetic gases can vary based on which agent is used.

• Nephrotoxicity with sevoflurane
• Carbon monoxide poisoning with desflurane
• Hematotoxicity with prolonged exposure to nitrous oxide
• Hepatotoxicity and reduced cardiac output with halothane

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Resources:

Clar, D. T., Patel, S., & Richards, J. R. (2025). Anesthetic Gases. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK537013/

Edgington, T. L., Muco, E., & Maani, C. V. (2025). Sevoflurane. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK534781/

Hoggard, A., Shienbaum, R., Mokhtar, M., & Singh, P. (2025). Gaseous Anesthetics. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK539880/

Miller, A. L., Theodore, D., & Widrich, J. (2025). Inhalational Anesthetic. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK554540/

Last Updated on August 28, 2025 by Maureen Osuna, MSN, RN