Nalbuphine reverses fentanyl-related EEG-changes in man

Nalbuphine, chemically related to naloxone however, with mixed agonist-antagonist activity, was considered to be of clinical interest in reversing opioid anesthesia. In an open-end study 15 patients (mean age 40 years) undergoing orthopedic surgery received nalbuphine (0.1 mg/kg) after fentanyl (total dose 17.4 micrograms/kg over a mean of 95 min). In order to establish the state of vigilance, continuous EEG-recording of the posterior region of the cortex (P3-O1) was done with the aid of power spectral analysis using fast Fourier transformation (FFT). Additionally blood pressure and heart rate were measured. The observed effects were compared with the awake unpremedicated preoperative state. In the EEG nalbuphine reversed the anesthesia-related increase in power in the delta (0.25-4 Hz) and decrease in alpha (8-12 Hz), beta 3 (20-25 Hz) and beta 4 (25-32 Hz) domain. After the 45th minute delta significantly increased while power in the beta-band unsignificantly dropped. Power in the alpha-band remained elevated throughout the whole postoperative period. In regard to blood pressure measurements nalbuphine induced an increase in systolic, diastolic pressure and heart rate 15% above control. These parameters declined towards the 30th minute; only heart rate reached predrug values at the 45th minute. With the aid of EEG-power spectral analysis it was demonstrated that nalbuphine seems a valuable tool for the reversal of opioid-induced cortical depression.