What are the uses and dosing guidelines for ketamine in medical settings?

Ketamine Uses and Dosing Guidelines in Medical Settings

Ketamine is recommended for specific clinical scenarios including anesthesia induction/maintenance, pain management in high-risk surgeries, and treatment of refractory pain, with dosing tailored to the clinical indication. 1, 2

Approved Indications

• Ketamine is FDA-approved as a sole anesthetic agent for diagnostic and surgical procedures that don't require skeletal muscle relaxation 2
• It can be used for induction of anesthesia prior to other general anesthetic agents 2
• It serves as a supplement to other anesthetic agents 2

Anesthesia Dosing

• Intravenous induction: 1-4.5 mg/kg (average 2 mg/kg) administered slowly over 60 seconds to produce 5-10 minutes of surgical anesthesia 2
• Intramuscular induction: 6.5-13 mg/kg (typically 9-13 mg/kg) producing surgical anesthesia within 3-4 minutes, lasting 12-25 minutes 2
• Maintenance: Repeat increments of one-half to full induction dose as needed 2

Perioperative Pain Management

• Intraoperative use: Small doses of ketamine are recommended in two specific scenarios: 1

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

• Dosing for perioperative pain: 1

  • Maximum dose of 0.5 mg/kg/h after anesthesia induction
  • Continuous infusion at 0.125-0.25 mg/kg/h
  • Infusion should be stopped 30 minutes before the end of surgery

Acute Pain Management

• For severe acute pain management, subanesthetic doses include: 1
  • Boluses <0.35 mg/kg
  • Infusions at 0.5-1 mg/kg/h
  • When used in IV-PCA (patient-controlled analgesia): 1-5 mg per dose 1

Chronic Pain Applications

• Ketamine has shown efficacy in treating neuropathic pain conditions through NMDA receptor antagonism 3
• Short-term infusions provide analgesia during administration, while prolonged infusions (4-14 days) may produce analgesic effects lasting up to 3 months 3

Administration Routes

• Primarily administered intravenously or intramuscularly (FDA-approved routes) 2
• Alternative routes reported in literature include oral, intranasal, rectal, subcutaneous, transdermal, and sublingual 4, 5
• Oral ketamine may be effective at doses 30-40% lower than parenteral doses 6

Special Considerations and Precautions

• Must be administered by or under direction of physicians experienced with general anesthetics 2
• Continuous vital sign monitoring is mandatory 2
• Emergency airway equipment must be immediately available 2
• The 100 mg/mL concentration requires proper dilution for IV administration 2
• Consider administering an antisialagogue prior to induction due to potential for salivation 2

Contraindications and Cautions

• Should not be used in patients with uncontrolled cardiovascular disease, pregnancy, active psychosis, severe liver dysfunction, or high intracranial/ocular pressure 1
• Continuation of ketamine treatment in the postoperative period increases risk of hallucinations without significantly enhancing analgesic effect 1
• Consider co-administration of benzodiazepines to minimize psychotomimetic side effects 2, 3, 6

Unique Benefits

• Produces bronchodilation, making it suitable for patients with asthma or acute bronchial constriction 4
• Maintains hemodynamic stability, making it appropriate for patients with unstable hemodynamics 4
• Lower risk of respiratory depression with relatively preserved airway reflexes compared to other anesthetics 4

Monitoring and Safety

• Close monitoring is mandatory, particularly for CNS, hemodynamic, renal, and hepatic symptoms 3
• In individuals with chronic ketamine use, monitor for genitourinary pain and consider cessation if symptoms persist 2
• Regular assessment of sedation levels and respiratory status is essential 1