Intravenous Anesthetic Agents - Uses, Types, Characteristics, Indications, and Contraindications

Introduction

Intravenous anesthetic agents are used in surgery to provide unconsciousness to the patient. There are different types of anesthetic agents used in surgery. The topic explains their use, side effects, and contraindications. The new innovative drugs are also listed below, which have overcome traditional drug drawbacks.

What Are Intravenous Anesthetic Agents?

Intravenous anesthetic agents are the drugs used to deliver to the patient's body by injecting into veins. They help to make the patient unconscious while surgery is ongoing. Some commonly used intravenous anesthetic agents are Propofol, Etomidate, Ketamine, and Barbiturates. They are directly delivered into the blood circulation. So, they have a rapid rate of onset. They travel from the site of an injection directly to the brain.

What Are the Uses of Intravenous Anesthetic Agents?

Intravenous anesthetic drugs are used:

• To provide anesthesia or maintain anesthesia.

• Single-use in short procedures.

• To keep the anesthesia for lengthy surgical procedures.

• To sedate the patient.

How Are Intravenous Anesthetic Agents Classified?

Intravenous anesthetic drugs are classified as:

1. Inducing Agents - These drugs are used initially in general anesthesia to induce anesthetic effects. Drugs like Thiopentone, Methohexitone, Propofol, and Etomidate come under it.

2. Slower Acting Agents - These drugs have a slower rate of action and thus help maintain general anesthesia. Drugs like Diazepam and Midazolam come under slow-acting agents.

What Are the Ideal Characteristics of Intravenous Anesthetic Agents?

Characteristics of intravenous anesthetic agents are:

• It should be safe to use.

• It should not cause any pain on injection.

• It should not have any severe effects on use.

• It should have a rapid rate of induction.

• It should have analgesic and antiepileptic properties.

• It should have minimal effects on the respiratory system and intracranial brain pressure.

• It should be safe for children, the elderly, and pregnant women.

What Are the Different Types of Intravenous Anesthetic Agents?

There are many intravenous anesthetics agents. Some of the commonly used anesthetics are:

Propofol - Propofol is the most frequently used anesthetic agent.

Indications -

• When early recovery from consciousness is required.

• Sedation in regional anesthesia and intensive care units.

• In cases of epilepsy.

Adverse Effects -

• Hypotension.

• Respiratory depression.

• Slow heart rate.

• Muscle twitching.

• Anaphylaxis (allergic reaction).

Contraindications -

• Hypersensitivity.

They are managed by discontinuation of Propofol along with supportive care.

Barbiturates - Thiopental, Methohexital, and Phenobarbital are common barbiturates in use. They are short-acting drugs.

Indications -

• Epilepsy.

• Sleep disorders.

• Maintenance of general anesthesia in intensive care units.

Side effects -

• Respiratory depression.

• Low blood pressure (hypotension).

Contraindications -

• Asthma patients.

• Acute porphyrias.

Benzodiazepines - Diazepam, Lorazepam, Midazolam and Chlordiazepoxide are under the benzodiazepine group. Midazolam is commonly used.

Indications -

• Induction of general anesthesia.

• Conscious sedation.

• Muscle spasticity.

• Anxiety.

Side Effects -

• Respiratory depression.

• Confusion.

• Headache.

• Fainting.

• Diarrhea.

• Chest muscle constriction.

Contraindications -

• Hypersensitivity to benzodiazepines.

• Glaucoma.

They are managed by the antidote Flumazenil.

Ketamine - Ketamine can alone be used in general anesthesia. Its acting is also short.

Indications -

• Induction and maintenance of anesthesia.

• Chronic pain.

• Epilepsy cases.

Side Effects -

• Increased intracranial pressure (pressure in the brain).

• Respiratory depression.

• Apnea.

Contraindication -

• Any allergy or hypersensitivity.

• Pregnancy in women.

• Heart disease.

Etomidate - It has a duration of ultra short-acting and rapid metabolism.

Indication -

• Onset and recovery rates are rapid in procedural sedation.

• Cushing syndrome cases.

Side Effects -

• Low blood pressure (hypotension).

• Postoperative nausea and vomiting.

• Adrenal gland suppression.

Contraindications

• Any previous infection in the body (sepsis).

• Chronic kidney disease.

• Liver disease.

Fentanyl - It is commonly used as an opioid.

Indications -

• In general anesthesia.

• As sedatives.

• As analgesics for pain relief.

Side Effects -

• Respiratory depression.

• Confusion, drowsiness.

• Nausea and vomiting.

• Hallucinations.

• Constipation.

Contraindications -

• In patients who cannot tolerate opioids.

• Liver failure patients.

• Asthma patients.

• Head trauma patients.

• Patients suffering gastrointestinal problems.

It is managed by Naloxone.

What Are the Advantages of Intravenous Anesthetic Agents?

The advantages of intravenous anesthetic agents are:

• Short-time surgeries.

• Outpatient surgeries.

• Surgeries that do not require muscle relaxation.

• They do not require special equipment to deliver anesthesia.

• It does not have any risk of fire.

• They do not pollute the environment as gasses do.

What Are the Disadvantages of Intravenous Anesthetic Agents?

Disadvantages of intravenous anesthetic agents are:

• The intravenous anesthetic can not be used in complicated surgeries.

• They can not be used in patients with respiratory and circulatory problems.

• Intravenous agents should be cautiously used in patients with kidney and liver problems.

• Overdose of the drug can be seen in elderly patients.

• Hypersensitivity symptoms like redness, rash, or itchiness on the skin can develop.

What Are the New Innovative Drugs in Intravenous Anesthetic Agents?

New drugs are formed to lower the side effects of the existing drugs and improve their results. Some new innovative drugs used as intravenous anesthetic agents are:

• Remimazolam - It is a derivative of Midazolam. Midazolam has drawbacks, like a lack of analgesia and prolonged recovery time. These drawbacks are now overcome with new innovative drugs like Remimazolam. Remimazolam is a short-acting drug that is used in liver and kidney patients. It has the combined property of Remifentanil and Midazolam. As a result, it has a more rapid onset and quicker recovery. It is mainly used in procedural sedation.

• ADV6209 - It is a derivative of Midazolam that can be orally consumed. It is innovative to use in child patients.

• Methoxycarbonyl Etomidate (MOC-Etomidate) - It is an Etomidate derivative to overcome the adrenal suppression effect of the Etomidate.

• 2, Disubstituted alkylphenols - It is a new Propofol derivative.

• AZD-3043 - It is a new Propofol alternative drug. They have a rapid onset of action with a faster recovery rate and minimal effects on the respiratory and cardiovascular systems.

Which Is the Better Way to Deliver Anesthesia Gas or Injection?

As intravenous anesthetic agents are injected into the arm directly into blood circulation, their onset rate is more rapid than gasses. However, gasses are used preferably for child patients to initially manage them to sleep before surgery. Nowadays, total intravenous anesthesia has been growing in demand. Total intravenous uses a combination of intravenous agents, but it is only applicable during general anesthesia. The use of total intravenous is better than gasses as no heavy equipment is needed in them, and it can be used in outpatient services easily.

Conclusion

Intravenous anesthetic agents are used in sedation and general anesthesia practices. These agents are classified into two types: inducing and slower-acting drugs. Widely used intravenous anesthesia are Propofol, Ketamine, and Midazolam. Innovative new medicines are formed to overcome the adverse effects of intravenous agents like Remimazolam and AZD-3043.