What is Ketamine?

• Rapidly acting NMDA receptor antagonist that can be used for Induction of General AnesthesiaInduction of General Anesthesia
  Introduction
  The start of a case represents one of the highest risk periods in the operation.
  
  After a surgical time-out, the tools required for a safe induction can be remembered with the MDSOLES ..., sedation, and Pain ManagementPain Management
  Introduction
  Pain management can be a complex topic in anesthesia. Patient factors, like age, comorbidities, and pre-existing chronic pain can help guide analgesia during the operative period. Surg...

Mechanism of Action & Pharmacokinetics ¹²

• Ketamine acts in a noncompetitive antagonistic mechanism of the NMDA receptor
• Secondary effects at the opiate, muscarinic, cholinergic and serotonergic receptors

Pharmacodynamics ^{1 2 3}

Cardiovascular

• Inhibits reuptake of norepinephrine which stimulates the sympathetic nervous system.
  • Transient increase in HR, BP, SVR
  • Can lead to increased coronary blood flow and myocardial oxygen demand.
• Generally, ketamine is a hemodynamically stable induction agent. If a patient is sick and has little catecholamine reserves, hypotension can occur with administration

Respiratory

• Minimal impact on respiratory drive & minute ventilation
• airway reflexes preserved; however, large doses can lead to an impaired airway
• Produces bronchodilation
• Increases airway secretions

Central Nervous System

• Increases cerebral metabolic rate and cerebral blood flow thereby increasing cerebral vasodilation
• Cataleptic state without amnesia can occur
  • hallucinations, delirium, dissociative are all possible
• Anticonvulsant properties
• Increased tone which can manifest as myoclonic contraction and vocalization

Indications ³

Anesthetic Indications

• Induction of General AnesthesiaInduction of General Anesthesia
  Introduction
  The start of a case represents one of the highest risk periods in the operation.
  
  After a surgical time-out, the tools required for a safe induction can be remembered with the MDSOLES ...
• Short term sedation and analgesia during procedures or other clinical indications
• Pain ManagementPain Management
  Introduction
  Pain management can be a complex topic in anesthesia. Patient factors, like age, comorbidities, and pre-existing chronic pain can help guide analgesia during the operative period. Surg...

Other Indications

• Treatment of refractory depression and suicidal ideation
• Widely used in the emergency department in short cases requiring short term anesthetic, such as fracture reductions

Dosing ²

• Induction doses are 1 - 2 mg/kg IV or 3-5 mg/kg IM
• Analgesia doses are 0.15 - 0.25 mg/kg IV as a push or 0.1-0.3 mg/kg/hour
• Half-life of redistribution = 11 - 16 minutes
• Half-life of elimination = 2 - 4 hours

Complications ^{2 3}

• dysphoria at intermediate dosing can be profound
  • analgesic doses generally tolerated well, high doses lead to complete sedation
• Most commonly, patients can experience nausea, vomiting, drowsiness and confusion
• Increased muscular tone with myoclonic contractions resembling seizures
• Use with caution in cardiac disease due to stimulatory effects

References