What it's for (Indications)
- Enflurane, a halogenated ether, is indicated for the induction and maintenance of general anesthesia.
- It provides dose-dependent central nervous system depression, leading to unconsciousness and immobility.
- Additionally, enflurane produces skeletal muscle relaxation suitable for many surgical procedures.
- Historically, it was widely used; however, its use has significantly declined with the introduction of newer volatile anesthetics possessing more favorable pharmacokinetic and safety profiles.
- It achieves these effects by profoundly depressing neural activity across various brain regions necessary for consciousness and pain perception.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | Dosage of enflurane is highly individualized and must be precisely controlled using a calibrated vaporizer. For induction of anesthesia, concentrations typically range from 0.5% to 4.5% in oxygen or an oxygen/nitrous oxide mixture, titrated slowly to effect based on the patient's age, physical status, and desired speed of induction. For maintenance, concentrations generally range from 0.5% to 3.0%, adjusted to maintain the desired depth of anesthesia, surgical stimulation, and muscle relaxation. The minimum alveolar concentration (MAC) for enflurane is approximately 1.68% in 100% oxygen for a 40-year-old adult, varying with age, concomitant medications, and patient comorbidities. Due to its cardiovascular and respiratory depressant effects, careful titration to the desired depth of anesthesia while continuously monitoring vital signs is imperative. |
Safety & Warnings
Common Side Effects
- Common side effects associated with enflurane administration include dose-dependent hypotension, profound respiratory depression (often necessitating ventilatory support), nausea, vomiting, and shivering during emergence from anesthesia.
- Less common but more serious adverse effects include malignant hyperthermia (as a potent trigger), dose-dependent seizure activity (especially with hyperventilation or high concentrations), renal dysfunction (due to fluoride metabolism), transient elevations in liver enzymes, and an increase in intracranial pressure.
- Cardiac arrhythmias, while possible, are less frequent than with some other halogenated agents, but vigilance for their occurrence is still required.
- Other potential effects include cerebral vasodilation and increased cerebral blood flow.
Serious Warnings
- Black Box Warning: **Serious Warnings:** **Malignant Hyperthermia (MH) Trigger:** Enflurane is a well-established and potent trigger for malignant hyperthermia (MH), a rare but life-threatening pharmacogenetic disorder characterized by a rapid, uncontrolled hypermetabolic state in skeletal muscle. This syndrome can manifest with tachycardia, hypercarbia, metabolic acidosis, muscle rigidity, hyperthermia, and rhabdomyolysis, potentially leading to renal failure, cardiac arrest, and death. Clinicians administering enflurane must be acutely aware of this risk and be fully prepared for immediate diagnosis and management, including discontinuation of all triggering agents, prompt administration of intravenous dantrolene sodium, and aggressive supportive therapy to control acidosis, hyperkalemia, and hyperthermia. A comprehensive personal and family history screening for MH susceptibility is paramount prior to anesthetic administration. Vigilant intraoperative monitoring for early signs of MH is essential. **Seizure Activity:** Enflurane has the potential to induce dose-dependent seizure activity, particularly when administered at higher concentrations or in conjunction with hypocapnia resulting from hyperventilation. Patients with a known history of epilepsy or other seizure disorders are at an increased risk. While electroencephalographic (EEG) changes suggestive of seizure activity are often observed, overt clinical convulsions may not always be present. Prudent use dictates employing the lowest effective concentration to achieve the desired anesthetic depth and avoiding excessive hyperventilation. Close neurological monitoring is advised, especially in susceptible individuals. The potential for cerebral irritation and increased intracranial pressure must be considered. **Renal Toxicity:** Although less nephrotoxic than some earlier halogenated ethers, enflurane undergoes hepatic metabolism to release inorganic fluoride ions. Elevated serum fluoride concentrations, particularly after prolonged administration or in patients with pre-existing renal impairment, have been associated with a potential for dose-dependent renal dysfunction. While overt high-output renal failure is rare with current usage practices, caution is advised in patients with compromised kidney function. Close monitoring of renal parameters is recommended, and alternative anesthetic agents should be considered in high-risk populations or for prolonged procedures. **Cardiovascular and Respiratory Depression:** Enflurane exerts profound dose-dependent depressant effects on the cardiovascular and respiratory systems. It can significantly reduce myocardial contractility, leading to hypotension and decreased cardiac output. Simultaneously, it causes marked respiratory depression, necessitating careful monitoring of ventilation and frequently requiring assisted or controlled mechanical ventilation. These physiological alterations demand continuous hemodynamic and ventilatory monitoring throughout the anesthetic period, with immediate access to resuscitative equipment and medications to manage severe bradycardia, hypotension, or respiratory compromise.
- Beyond the serious warnings detailed in the specific section, other important considerations for enflurane include its potential to cause significant myocardial depression and dose-dependent hypotension, requiring careful fluid management and, occasionally, vasopressor support to maintain hemodynamic stability.
- It is a potent respiratory depressant, necessitating continuous monitoring and active management of ventilation to prevent hypoxia and hypercarbia.
- Enflurane can also increase cerebral blood flow and intracranial pressure, warranting extreme caution in patients with pre-existing intracranial pathology where such increases could be detrimental.
- Its use in obstetrics can lead to dose-dependent uterine relaxation, increasing the risk of postpartum hemorrhage.
- Enflurane potentiates the effects of non-depolarizing neuromuscular blockers and other central nervous system depressants, requiring dosage adjustments of these concomitant medications to avoid prolonged paralysis or excessive sedation.
- Close monitoring of all physiological parameters is essential throughout the anesthetic period.
How it Works (Mechanism of Action)
Enflurane produces general anesthesia through a complex and multifactorial interaction with various neural targets in the central nervous system. Its primary mechanism is believed to involve potentiation of inhibitory neurotransmission, particularly by enhancing the activity of gamma-aminobutyric acid (GABA) at GABA-A receptors, increasing the influx of chloride ions into neurons. This leads to hyperpolarization and widespread neuronal inhibition, resulting in unconsciousness, immobility, and amnesia. Additionally, enflurane modulates other ion channels, such as potassium channels, and inhibits excitatory neurotransmitter receptors, including N-methyl-D-aspartate (NMDA) receptors. These combined effects result in profound neuronal depression. It also causes dose-dependent depression of myocardial contractility and vascular smooth muscle relaxation, contributing to its hypotensive effects, and directly depresses the respiratory drive, affecting the chemoreceptors and central respiratory centers.
Commercial Brands (Alternatives)
No other brands found for this formula.