Ketamine's Hemodynamic Effects

Introduction to Hemodynamic Effects

Ketamine produces a dose-dependent increase in heart rate, blood pressure, and cardiac output through stimulation of the sympathetic nervous system, according to the American Gastroenterological Association 1, 2

Ketamine causes less hypotension than etomidate in septic patients (51% vs 73%), as reported by the Society of Critical Care Medicine 3, 4
Conversely, ketamine is associated with higher rates of post-RSI hypotension compared to etomidate (OR 2.7) in septic patients, also reported by the Society of Critical Care Medicine 3, 4, 5
In emergency department settings, peri-intubation hypotension rates were higher with ketamine (18.3%) than with etomidate (12.4%), according to the Society of Critical Care Medicine 3, 4, 5

The European Society of Cardiology recommends avoiding ketamine in patients with ischemic heart disease, cerebrovascular disease, or hypertension due to its potential cardiovascular stimulant effects 1, 6
In patients with sepsis or critical illness, the hemodynamic response to ketamine may be blunted or even reversed, as reported by the Society of Critical Care Medicine 3, 4, 5

Ketamine is associated with relative hemodynamic stability, making it an attractive induction drug for trauma care 7
Historically, there have been concerns about using ketamine in patients with head injury because of the risks of increased intracranial pressure, but these concerns are of little practical significance, and ketamine is now frequently used in pre-hospital emergency anesthesia (PHEA) in patients with head injury 7
Ketamine is now frequently used in pre-hospital emergency anesthesia (PHEA) in patients with head injury, and its administration was not associated with worse survival or disability in traumatic brain injury patients 7

The American Society of Anesthesiologists recommends ketamine for patients with brain injury due to its unique hemodynamic benefits, including maintaining or increasing cerebral perfusion pressure, and providing relative hemodynamic stability through sympathomimetic effects 8
The World Health Organization suggests that ketamine does not increase intracranial pressure compared to opioids, with a meta-analysis showing a mean difference of 1.94 mmHg (95% CI, -2.35, 6.23; P = 0.38) 9
The American College of Emergency Physicians states that ketamine can be used for postoperative pain management, with boluses of less than 0.35 mg/kg or infusions at 0.5-1 mg/kg/h 9
The FDA recommends avoiding ketamine in patients with uncontrolled cardiovascular disease, active psychosis, severe liver dysfunction, or high ocular pressure 9
The European Society of Anaesthesiology notes that ketamine's sympathomimetic effects may be disadvantageous after resuscitation from cardiac arrest or in patients with severe cardiac disease, producing dose-dependent increases in heart rate, blood pressure, and cardiac output 8, 10, 11
The American Academy of Neurology reports that emergence reactions occur in 10-30% of adults receiving ketamine, manifesting as floating sensations, vivid dreams, hallucinations, and delirium, and can be minimized with co-administration of midazolam 10, 11

High intracranial pressure is not considered an absolute contraindication by recent evidence, as ketamine does not increase ICP compared to opioids, according to the World Journal of Emergency Surgery 12
Active psychosis is a relative contraindication, as emergence reactions can occur in 10-30% of adults, but can be minimized with co-administration of benzodiazepines, as noted in the World Journal of Emergency Surgery 12
Severe liver dysfunction is a relative contraindication, as ketamine undergoes extensive hepatic metabolism, according to the World Journal of Emergency Surgery 12
Pregnancy is a contraindication, as all ketamine formulations are contraindicated in women who are or may become pregnant, as stated in the World Journal of Emergency Surgery 12 and Diabetes Care 13

The American College of Obstetricians and Gynecologists and other guideline societies may have specific recommendations for ketamine use in pregnancy, but according to Diabetes Care, ketamine is contraindicated in pregnant women 13
The FDA and other regulatory agencies contraindicate ketamine in patients with certain conditions, including severe liver dysfunction and pregnancy, as noted in the World Journal of Emergency Surgery 12 and Diabetes Care 13

In critically ill patients with depleted catecholamine stores, including those with chronic cardiovascular disease, ketamine's hemodynamic response may be blunted or even reversed, leading to hypotension and potential cardiac arrest, as noted by the Society of Critical Care Medicine 14, 15

The expected blood pressure increase with ketamine may not occur in patients with depleted catecholamine stores, and paradoxical hypotension can develop, according to the Society of Critical Care Medicine 14, 15
Cardiac decompensation may result from ketamine's hemodynamic effects in compromised patients, highlighting the need for careful patient selection and monitoring, as recommended by the American Heart Association 14, 15