Haemodynamic and EEG changes during rapid-sequence induction of anaesthesia.

The relationship between the changes in haemodynamic function and the electroencephalogram (EEG) during rapid-sequence induction of anaesthesia was studied in 15 ASA I patients. Anaesthesia was induced with a bolus thiamylal (5 mg.kg-1 iv) followed by succinylcholine (1 mg.kg-1). Tracheal intubation was attempted one minute after the injection of succinylcholine. The EEG was monitored by a computerized aperiodic analysis device, the Lifescan (Neurometrics, San Diego, CA) using the activity edge (AE) to detect brain electrical activity. After induction of anaesthesia, systolic blood pressure (sBP) decreased by 11% from the baseline value, and the AE decreased from 13.0 Hz to 3.4 Hz. Following tracheal intubation, the sBP increased from the post-induction values by 44% (P < 0.05), and the AE increased to 13.1 Hz (P < 0.05) simultaneously. In conclusion, rapid-sequence induction using thiamylal (5 mg.kg-1) caused depression in brain activity as assessed by AE, while laryngoscopy and tracheal intubation caused an increase in activity. This indicates that this dose of thiamylal for rapid-sequence induction may not be sufficient to sustain an adequate anaesthetic level and blunt the haemodynamic responses to intubation.