Yes, ketamine is used for general anesthesia and has been since the 1960s. It remains one of the most versatile anesthetic agents available, listed on the World Health Organization’s Essential Medicines List since 1984 specifically as an injectable general anesthetic. What makes ketamine unusual is that it works through an entirely different brain mechanism than most other anesthetics, giving it a unique set of advantages that make it the preferred choice in specific clinical situations.
How Ketamine Works Differently
Most general anesthetics, like propofol, work by enhancing the brain’s natural braking system. They amplify inhibitory signals until consciousness shuts down. Ketamine takes a different route. It blocks a receptor involved in excitatory signaling, essentially cutting off one of the brain’s main communication channels rather than turning up the “off switch.”
At low doses, this blockade produces sedation, pain relief, and a strange sense of disconnection from the body and environment. At higher doses, it produces profound unconsciousness with strong pain control. This is why ketamine anesthesia is called “dissociative anesthesia,” a term that distinguishes it from the deep, quiet suppression caused by other agents. Patients under ketamine may keep their eyes open, move slightly, or appear to be in a trance-like state rather than fully “asleep” in the traditional sense.
This mechanism also creates unusual brain wave patterns. Rather than simply quieting brain activity, ketamine generates bursts of gamma and slow-delta oscillations through interactions between excitatory and inhibitory brain circuits. These patterns are fundamentally different from those seen under propofol or other conventional anesthetics, which is one reason monitoring ketamine anesthesia requires experienced interpretation.
Why Ketamine Is Chosen Over Other Anesthetics
Ketamine’s biggest advantage is what it doesn’t do. Unlike propofol or opioid-based approaches, ketamine stimulates rather than suppresses breathing. Research published in Anesthesiology found that ketamine increased airflow, breathing rate, and effective inspiratory time by 1.5 to 2 times compared to baseline. It also boosted the activity of the tongue muscle responsible for keeping the airway open by 1.5 to 5 times the levels seen during propofol-induced unconsciousness. In practical terms, a patient under ketamine is far less likely to stop breathing or have their airway collapse.
Ketamine also raises blood pressure, heart rate, and cardiac output by triggering the release of the body’s own adrenaline-like hormones. For a healthy patient undergoing elective surgery, this effect is unwanted. But for someone who has lost blood from a traumatic injury and whose blood pressure is already dangerously low, ketamine can maintain circulation where other anesthetics would cause cardiovascular collapse. This makes it the anesthetic of choice for hemodynamically unstable trauma patients.
There is one important caveat: in patients whose adrenaline reserves are already exhausted from prolonged shock or critical illness, ketamine’s direct effect on the heart is actually slightly depressive. The stimulating effects depend on the body having stress hormones left to release.
Where Ketamine Is the Primary Choice
Several clinical settings rely heavily on ketamine as a first-line anesthetic:
- Trauma and emergency medicine. Ketamine’s ability to maintain blood pressure and breathing makes it ideal for rapid sequence intubation in injured patients. It can be given intravenously, intramuscularly, through a bone (intraosseous), or even as a nasal spray, which gives providers options when IV access is difficult.
- Military and combat medicine. Tactical Combat Casualty Care guidelines recommend ketamine for casualties with moderate to severe pain. Its hemodynamic and respiratory stability, combined with flexible dosing routes, makes it practical in austere field conditions where monitoring equipment is limited.
- Pediatric procedures. Ketamine serves as an alternative to opioid-based sedation in children over 3 months of age, particularly for painful procedures like fracture reduction or burn care. The intramuscular route is especially useful in young children where starting an IV can be challenging.
- Low-resource settings. In hospitals without ventilators or advanced airway equipment, ketamine’s preservation of spontaneous breathing allows surgery to proceed safely. This is a major reason the WHO has kept it on the Essential Medicines List for four decades.
- Brief painful procedures. For short procedures involving musculoskeletal injuries or burns, ketamine provides both unconsciousness and pain relief in a single drug, avoiding the need for separate sedatives and painkillers.
Dosing and How It’s Given
For inducing general anesthesia, the standard intravenous dose ranges from 1 to 4.5 mg per kilogram of body weight, given slowly. When combined with a sedative like midazolam, lower doses of 0.5 to 2 mg/kg are often sufficient. For intramuscular injection, the doses are higher (6.5 to 13 mg/kg) because the drug absorbs more slowly through muscle tissue.
The intramuscular option is a significant practical advantage. Most other induction agents require IV access, which can be difficult to establish in children, burn patients, or trauma victims in the field. A ketamine injection into the thigh muscle can have a patient sedated within minutes.
Emergence Reactions: The Main Drawback
The most well-known side effect of ketamine anesthesia is what clinicians call emergence phenomena. As the drug wears off, 10% to 20% of adult patients experience vivid dreams, hallucinations, confusion, or agitation. These reactions can be distressing but are typically short-lived.
To reduce this risk, a sedative is commonly given alongside ketamine. One popular approach combines ketamine with propofol in a 1:1 ratio, a mixture sometimes called “ketofol.” The propofol counteracts ketamine’s tendency to cause nausea and psychological disturbance, while ketamine adds pain relief that propofol lacks and reduces the respiratory depression propofol can cause. This combination allows lower doses of each drug, widening the margin of safety. The result is effective sedation with fewer airway complications and a shorter recovery time compared to using ketamine alone.
Situations Where Ketamine Is Avoided
Ketamine’s stimulating cardiovascular effects, while helpful in trauma, make it a poor fit for patients with uncontrolled high blood pressure, certain heart conditions, or situations where a spike in heart rate could be dangerous. It was also historically considered strictly off-limits in patients with head injuries due to concerns about raising pressure inside the skull. That view has softened considerably over the past two decades, with military and civilian trauma data supporting its safety in head-injured patients when used appropriately. Current joint position statements endorse ketamine for prehospital and hospital treatment of acute trauma patients, including pediatric patients with head injuries in combat settings.
Patients with a history of psychosis or severe psychiatric illness are generally not ideal candidates, given ketamine’s psychoactive properties. And because ketamine increases secretions in the mouth and airways, medications to dry these secretions are often given beforehand to reduce the risk of coughing or airway irritation.
What Recovery Feels Like
Waking up from ketamine anesthesia feels different from waking up after propofol. Rather than a clean transition from unconscious to alert, patients often pass through a dreamlike period that can last 15 to 45 minutes. Some people find these dreams pleasant or neutral; others find them unsettling. The disorientation typically clears within an hour or two, though some grogginess may linger.
For the majority of patients (80% to 90%) who don’t experience significant emergence reactions, recovery is smooth but noticeably different from the “lights off, lights on” quality of propofol. Being in a calm, quiet environment during recovery helps, and many clinicians minimize stimulation during the wake-up period to reduce the chance of agitation.