Ketamine Dosing and Postoperative Hallucinations: Clinical Implications

Understanding the Dose-Dependent Effects of Ketamine

A recent study published on May 23, 2026, in an unknown Tier 1 venue, examines the impact of different ketamine doses on postoperative hallucinations. The research, involving 62 patients aged 16 to 60 undergoing various surgeries under general anesthesia, reveals significant dose-dependent effects on hallucination types and severity. Ketamine doses ranged from 30 mg/kg to 100 mg/kg, with administration durations from 10 to over 40 minutes.

Mechanisms and Clinical Context

Ketamine, a dissociative anesthetic, is known for its psychotropic effects, including hallucinations. The study found that higher doses and longer administration durations of ketamine significantly increased the incidence and severity of postoperative hallucinations. These effects were measured using a questionnaire assessing visual, auditory, and combined hallucinations, rated as mild, moderate, or severe.

During the induction stage, propofol was used at 1-3 mg/kg, while midazolam was administered at 0.3-0.03 mg/kg in the premedication stage. Isoflurane and sevoflurane were used for maintenance, and muscle relaxants such as atracurium and rocuronium facilitated the procedure.

Implications for Anesthesia Practice

The findings underscore the importance of precise ketamine dosing in perioperative care to minimize adverse psychological effects. Clinicians should consider patient-specific factors, such as age and medical history, when determining ketamine doses. This approach could enhance patient outcomes by reducing the risk of severe hallucinations and associated distress.

Risks and Unknowns

While the study provides valuable insights, it also highlights areas requiring further research. The long-term psychological effects of postoperative hallucinations remain unclear, and the study's relatively small sample size limits the generalizability of the findings. Future research should explore these aspects to develop comprehensive guidelines for ketamine use in anesthesia.

Looking Forward

As the medical community continues to explore the therapeutic potential of ketamine, understanding its dose-dependent effects is crucial. This study serves as a stepping stone for further investigations into optimizing ketamine use in clinical settings, potentially leading to safer anesthesia practices and improved patient care.