Related Experiment Video

Updated: Jan 18, 2026

Application of Dixon's Up-and-Down Design to Estimate the Minimum Alveolar Concentration of Sevoflurane in Rats with Refined Movement Classification
03:02

Application of Dixon's Up-and-Down Design to Estimate the Minimum Alveolar Concentration of Sevoflurane in Rats with Refined Movement Classification

Published on: July 25, 2025

521

Effects of midazolam and nitrous oxide on the minimum anesthetic concentration of isoflurane in the ball python

Cédric B Larouche1, Craig Mosley2, Hugues Beaufrère3

  • 1Toronto Zoo, Scarborough, ON, Canada; Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.

Veterinary Anaesthesia and Analgesia
|October 1, 2019
PubMed
Abstract

Insights

Midazolam significantly reduced the minimum anesthetic concentration of isoflurane (MAC_ISO) by 57% in ball pythons. Nitrous oxide (N2O) provided a smaller, yet significant, 17% reduction in MAC_ISO.

Area of Science:

  • Veterinary Anesthesiology
  • Herpetological Medicine
  • Comparative Physiology

Background:

  • Anesthetic protocols in reptiles, particularly ball pythons (Python regius), require careful consideration due to species-specific metabolic rates and drug responses.
  • Isoflurane is a common inhalant anesthetic, but its minimum anesthetic concentration (MAC_ISO) can be influenced by co-administered agents.
  • Understanding synergistic or additive effects of premedications and adjuncts is crucial for optimizing anesthetic safety and efficacy in exotic species.

Purpose of the Study:

  • To determine the impact of midazolam and nitrous oxide (N2O) on the minimum anesthetic concentration of isoflurane (MAC_ISO) in ball pythons.
  • To compare the dose-sparing effects of midazolam and N2O when used as premedication or adjuncts to isoflurane anesthesia.
  • To provide data that can inform anesthetic protocols for ball pythons and potentially other reptilian species.

Main Methods:

  • A prospective, crossover, randomized, semi-blinded study was conducted on nine healthy adult female ball pythons.
  • Three anesthetic protocols were evaluated: midazolam with isoflurane-oxygen (MID-O2), saline with isoflurane-oxygen (SAL-O2), and saline with isoflurane and 50% nitrous oxide (SAL-N2O).
  • MAC_ISO was determined using a bracketing technique with logistic regression, and electrical stimulation served as the supramaximal stimulus. Blood-gas analysis was performed.

Main Results:

  • The MAC_ISO in ball pythons at a body temperature of approximately 30°C was 1.11% for SAL-O2.
  • Midazolam (MID-O2) significantly decreased MAC_ISO by 57% to 0.48% (p < 0.001).
  • Nitrous oxide (SAL-N2O) resulted in a significant but more modest decrease in MAC_ISO by 17% to 0.92% (p = 0.016). PO2 was lower in MID-O2 and SAL-N2O groups.

Conclusions:

  • Midazolam demonstrates a potent dose-sparing effect on isoflurane MAC in ball pythons.
  • Nitrous oxide offers a moderate MAC-reducing effect in this species.
  • The determined MAC_ISO values for isoflurane in ball pythons are lower than previously reported for other reptiles, highlighting species-specific anesthetic requirements.
Keywords:
blood gasinhalation anesthesiaminimum alveolar concentrationreptilesedativesnake

More Related Videos

Cavernous Nerve Stimulation and Recording of Intracavernous Pressure in a Rat07:43

Cavernous Nerve Stimulation and Recording of Intracavernous Pressure in a Rat

Published on: April 23, 2018

13.4K
Assessing Changes in Volatile General Anesthetic Sensitivity of Mice after Local or Systemic Pharmacological Intervention08:49

Assessing Changes in Volatile General Anesthetic Sensitivity of Mice after Local or Systemic Pharmacological Intervention

Published on: October 16, 2013

14.4K

Related Concept Videos

Inhalational Anesthetics: Overview01:20

Inhalational Anesthetics: Overview

Inhalation anesthetics are drugs that induce general anesthesia upon inhalation. They work by increasing the sensitivity of GABAA receptors or inhibiting NMDA receptors, leading to a decrease in central nervous system activity. The depth of anesthesia can be rapidly adjusted by changing the concentration of the inhaled gas. Some common examples of inhalational anesthetics include volatile liquids like isoflurane, desflurane, sevoflurane and gases like xenon and nitrous oxide. Isoflurane, a...
1.0K
Parenteral Anesthetics: Overview01:24

Parenteral Anesthetics: Overview

Intravenous anesthetics are drugs administered parenterally to induce anesthesia or sedation. Propofol is a widely used agent formulated as a 1% emulsion in soybean oil, glycerol, and egg phosphatide. It induces rapid anesthesia primarily due to its rapid distribution from the bloodstream to target tissues and is metabolized in the liver. However, it can cause significant pain on injection and hypertriglyceridemia. Fospropofol, a water-based prodrug of propofol, lacks these adverse effects.
611
Stages of General Anesthesia01:22

Stages of General Anesthesia

Various sedation levels offer significant advantages in facilitating procedural interventions for patients undergoing medical or invasive surgical procedures. These levels span from anxiolysis to general anesthesia, providing a spectrum of sedative effects to cater to specific patient needs. Anxiolysis reduces anxiety and is achieved through minimal sedation, enabling patients to remain awake and responsive while feeling more at ease during the procedure. This level can benefit minor...
1.5K
General Anesthesia: Overview01:24

General Anesthesia: Overview

Anesthesia is a medical procedure that uses drugs for CNS suppression to enable painless surgeries and procedures. The selection of anesthetics is influenced by their pharmacokinetic properties, side effects, and patient characteristics. Various types of anesthesia include general, local, regional, spinal, and inhalational.
General anesthesia induces unconsciousness in the whole body, while the others target specific areas or sensations. It is administered to minimize adverse effects, maintain...
593
Local Anesthetics: Clinical Application as Spinal Anesthesia01:11

Local Anesthetics: Clinical Application as Spinal Anesthesia

Spinal anesthetics are given during lower abdomen and limb surgeries to block sensory and motor neurons. They are administered in the mid to low lumbar regions, primarily acting on the cauda equina's nerve roots. The blockade level depends on the local anesthetic (LA) concentration. Usually, low LA concentrations are sufficient to block sensory fibers, while only high LA concentrations block motor fibers. Other factors like injection volume and speed, the patient's posture, and the drug...
1.3K
Skeletal Muscle Relaxants: Therapeutic Uses01:31

Skeletal Muscle Relaxants: Therapeutic Uses

Skeletal muscle relaxants are used to relax muscle tone and alleviate painful muscle contractions. However, the choice of skeletal muscle relaxants depends on the duration of the surgical procedure in order to minimize potential side effects. Skeletal muscle relaxants like neuromuscular blocking agents [NMBAs] are commonly employed as adjuvants alongside general anesthetics in clinical settings. NMBAs are also used to maintain controlled ventilation during surgery of the larynx or pharynx...
918