A single intravenous dose of esketamine (0.25 mg/kg) given before anesthesia induction lowers the risk of postoperative delirium in adults undergoing on-pump cardiac valve surgery. In a randomized controlled trial of 112 patients (average age 52 years, 53.6% female), delirium occurred in 23.2% of those given esketamine versus 44.6% in the placebo group, a relative risk reduction of about half. Esketamine also reduced the number of patients with multiple delirium episodes and the hyperactive subtype. The results suggest esketamine is an effective preventive intervention for delirium in this surgical population.
A low-dose ketamine infusion in the intensive care unit (ICU) after surgery reduced fentanyl consumption by 15% (68 µg over 24 hours) compared with placebo, a small but statistically significant opioid-sparing effect. The effect appeared stronger in patients who had intraabdominal surgery. Pain and sedation scores did not differ between groups, and no acute adverse effects were observed. However, a secondary follow-up (average 43 months later) of 45 patients found that those who received ketamine reported a higher incidence of frightening and delusional memories of their ICU stay (65% vs 41%). Low-dose ketamine modestly reduces opioid use but may increase the risk of traumatic memories after critical illness.
Psychostimulants like amphetamines, cocaine, and entactogens pose challenges for anesthesia providers because each subclass has unique receptor activity and effects. These substances alter how anesthetic agents, adjuvants, and pain medications work, complicating perioperative care. The article reviews the epidemiology, pharmacology, and clinical implications of acute or chronic psychostimulant exposure, providing a foundation for safe management during surgery.