Can the CSM be used when the agents are Ketamine or Nitrous Oxide (N2O)?
As opposed to most commonly used volatile and intravenous hypnotic agents, Ketamine is a “dissociative” drug. It activates some areas of the brain while inhibiting others. The result is an altered EEG signal. For this reason the CSM (as well as all EEG-based monitors for depth of anaesthesia) cannot provide reliable information on these patients. Nitrous Oxide is primarily used as an analgesic drug. The CSM responds to hypnotic agents. You will find NO changes in EEG (CSI) using N2O alone (normal doses), but you will find changes in the CSI in combination with a narcotic, as N2O potentiates its effect.
