What are the guidelines for using ketamine (Ketamine) for anesthesia and pain management?

Guidelines for Ketamine Use in Anesthesia and Pain Management

Ketamine is recommended for anesthesia induction and maintenance, as well as for pain management in specific clinical scenarios, with dosing and administration protocols tailored to the clinical context. 1

Indications for Ketamine Use

Anesthesia

• FDA-approved indications 1:
  • As a sole anesthetic agent for diagnostic and surgical procedures not requiring skeletal muscle relaxation
  • For induction of anesthesia before administering other general anesthetic agents
  • As a supplement to other anesthetic agents

Pain Management

• Recommended for intraoperative use in two specific situations 2:

  1. Surgery with high risk of acute pain or chronic postoperative pain
  2. Patients vulnerable to pain, particularly those taking long-term opioids or with opioid addiction

• Additional pain indications 3:

  • Treatment-resistant pain with inadequate control despite high-dose opioids
  • Opioid tolerance or hyperalgesia
  • Neuropathic pain components

Dosing Guidelines

Anesthesia Dosing

• Intravenous induction: 1-4.5 mg/kg (average 2 mg/kg) for 5-10 minutes of surgical anesthesia 1

  • Administer slowly over 60 seconds to prevent respiratory depression
  • Alternative: 0.5 mg/kg/min as intravenous infusion

• Intramuscular induction: 6.5-13 mg/kg 1

  • 9-13 mg/kg typically produces surgical anesthesia within 3-4 minutes
  • Effect usually lasts 12-25 minutes

• Maintenance: Repeat increments of one-half to full induction dose as needed 1

Pain Management Dosing

• Intraoperative anti-hyperalgesic use 2:

  • Maximum dose: 0.5 mg/kg/h after anesthesia induction
  • Continuous infusion: 0.125-0.25 mg/kg/h
  • Stop infusion 30 minutes before end of surgery

• Acute pain management 3:

  • Initial dose: 0.5 mg/kg IV bolus
  • Maintenance: 1-2 μg/kg/min infusion
  • For breakthrough pain in PACU: 0.5 mg/kg titrated to effect
  • For S-ketamine: Consider reduced dose of 0.25-0.5 mg/kg

Administration Considerations

Route of Administration

• Intravenous: Most common route for anesthesia and perioperative pain management 1, 4
• Intramuscular: Effective for induction when IV access is challenging 1
• Alternative routes with demonstrated efficacy 4:
  • Subcutaneous
  • Intranasal
  • Oral/sublingual/transmucosal (lower bioavailability due to first-pass metabolism) 5

Administration Precautions

• Must be administered by or under direction of physicians experienced in:

  • Administration of general anesthetics
  • Maintenance of patent airway
  • Oxygenation and ventilation 1

• Required safety measures 1:

  • Continuous vital sign monitoring
  • Immediate availability of emergency airway equipment
  • Proper dilution of 100 mg/mL concentration before IV administration
  • Use immediately after dilution

• Premedication: Administer an antisialagogue prior to induction to manage potential salivation 1

Clinical Benefits and Outcomes

Anesthesia Benefits

• Produces hemodynamically stable anesthesia via central sympathetic stimulation 5
• Maintains airway tone, respiratory drive, and hemodynamic stability 6
• Does not affect respiratory function significantly 5

Pain Management Benefits

• Short-term benefits 2:

  • Decreases acute pain intensity for 24 hours
  • Reduces morphine consumption (mean drop of 15 mg in 24 hours)
  • Decreases risk of postoperative nausea and vomiting

• Long-term benefits 2:

  • Estimated 30% decrease in incidence of chronic pain three months after surgery (low level of evidence)

Adverse Effects and Monitoring

Common Adverse Effects

• Psychotomimetic effects (dysphoria, nightmares, hallucinations) 3
• Nausea 3
• Purposeless and tonic-clonic movements of extremities during anesthesia 1
• Neuropsychological manifestations during emergence 1

Serious Concerns

• Potential for genitourinary pain with chronic use 1
• Risk of abuse with long-term or domiciliary treatment 4

Monitoring Requirements

• Vital sign monitoring during administration 3
• Assessment of sedation levels and respiratory status 3
• Monitoring for at least 2 hours after administration for dissociative effects 3

Special Considerations

Contraindications and Cautions

• Use with caution in patients with:

  • Uncontrolled cardiovascular disease
  • Pregnancy
  • Active psychosis
  • Severe liver dysfunction
  • High intracranial or ocular pressure 3
  • Chronic alcoholism or acute alcohol intoxication 3

• Not recommended for:

  • Patients who have not followed nil per os guidelines 1
  • Use alone in procedures involving pharynx, larynx, or bronchial tree 3

Adjunctive Therapies

• Consider benzodiazepine administration to prevent neuropsychological manifestations during emergence 1

Long-term Use Considerations

• Continuation of ketamine treatment in the postoperative period increases risk of hallucinations without significantly enhancing analgesic effect 2
• Consider cessation if genitourinary pain continues in the setting of other genitourinary symptoms 1
• Safety issues in long-term use remain to be fully resolved 5

Ketamine's unique pharmacological profile makes it valuable in both anesthesia and pain management, but proper patient selection, dosing, and monitoring are essential to maximize benefits while minimizing risks.