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Ketamine: Effect on BIS

Numerous studies and meta-analysis have documented an increase in bispectral index (BIS) values on patients who receive ketamine. This increase has been noted in patients maintained on both intravenous and inhalational anesthesia. Furthermore, Sakai et al. examined the effects of ketamine on BIS values when various clinical end points were reached: response to verbal commands, eyelash reflex, response to nasal mucosa stimulation. Similarly, patients receiving a ketamine bolus with a propofol infusion had higher BIS values at loss of the above clinical end points compared to those receiving only a propofol infusion.


  1. Hans P, Dewandre PY, Brichant JF, Bonhomme V. Comparative effects of ketamine on Bispectral Index and spectral entropy of the electroencephalogram under sevoflurane anaesthesia. Br J Anaesth. 2005; 94(3). 336-40 Link
  2. Hayashi K, Tsuda N, Sawa T, Hagihira S. Ketamine increases the frequency of electroencephalographic bicoherence peak on the alpha spindle area induced with propofol. Br J Anaesth. 2007; 99(3). 389-95 Link
  3. Hirota K, Kubota T, Ishihara H, Matsuki A. The effects of nitrous oxide and ketamine on the bispectral index and 95% spectral edge frequency during propofol-fentanyl anaesthesia. Eur J Anaesthesiol. 1999; 16(11). 779-83 Link
  4. Sakai T, Singh H, Mi WD, Kudo T, Matsuki A. The effect of ketamine on clinical endpoints of hypnosis and EEG variables during propofol infusion. Acta Anaesthesiol Scand. 1999; 43(2). 212-6 Link