Ketamine Use in the Cardiovascular Intensive Care Unit (CVICU)
Ketamine is recommended as an adjunctive agent for sedation and analgesia in the CVICU, particularly to reduce opioid requirements and provide pain relief when pain is refractory to opioids and other agents. 1
Mechanism and Benefits
- Ketamine functions as an N-methyl-D-aspartate/glutamate receptor (NMDA) antagonist that interferes with normal excitatory effects of glutamate and aspartate while also interacting with opioid receptors 1
- Unlike conventional sedatives, ketamine preserves pharyngeal and laryngeal protective reflexes, lowers airway resistance, increases lung compliance, and is less likely to produce respiratory depression 2
- Ketamine causes sympathetic stimulation, which may help maintain hemodynamic stability in critically ill patients 2, 3
Dosing Recommendations for CVICU
- For sedation and analgesia: Sub-anesthetic doses (0.1-0.5 mg/minute as a microdrip infusion) can be administered with opioids to help reduce the overall opioid dose 1, 4
- For induction: 1-2 mg/kg IV when used as an induction agent 4
- For continuous infusion: 0.5 mg/kg IV bolus followed by 1-2 μg/kg/min infusion as an adjunct to opioid therapy 5, 6
Administration Protocol
- Continuous monitoring of vital signs, including oxygen saturation, heart rate, and blood pressure, is required during ketamine administration 5
- Ketamine should be administered by or under the direction of physicians experienced in the administration of general anesthetics, maintenance of a patent airway, and oxygenation and ventilation 4
- Emergency airway equipment must be immediately available 4
Clinical Applications in CVICU
- Opioid-sparing effect: Ketamine can decrease the overall quantity of opioids administered and reduce the incidence and severity of opioid-related side effects 1, 6
- Hemodynamic stability: A trend toward decreased vasopressor requirements has been observed in septic shock patients receiving ketamine sedation 3
- Refractory pain management: Particularly useful when pain is refractory to opioids and other agents 1
Potential Side Effects and Precautions
- Psychotomimetic side effects (dysphoria, nightmares, hallucinations) may occur, especially at higher ketamine doses 1
- Concern for these adverse psychotropic effects and delirium is a major limiting factor in ketamine use among intensivists 7
- Consider co-administration with a benzodiazepine to reduce the risk of emergence reactions 4
- Use with caution in patients with ischemic heart disease, cerebrovascular disease, or hypertension 5
Special Considerations for CVICU Patients
- Ketamine may be particularly beneficial in patients with asthma exacerbation, opioid tolerance, or severe acute respiratory distress syndrome 7
- The drug's unique pharmacological profile makes it an appealing alternative for analgosedation in hemodynamically unstable patients 2, 3
- Due to its lipophilicity and large volume of distribution, ketamine can accumulate with sustained infusions, requiring careful monitoring and dose adjustments 2