Slow EEG-power spectra correlate with haemodynamic changes during laryngoscopy and intubation following induction with fentanyl or sufentanil.

We studied nociception-associated arousal following laryngoscopy and intubation in patients scheduled for elective open heart surgery, using EEG power spectra and hemodynamics. Either fentanyl (7 micrograms/kg; n = 30) or sufentanil (1 microgram/kg; n = 30) were given in a randomized fashion to induce anesthesia in heavily premedicated patients, followed by pancuronium bromide (100 micrograms/kg). EEG-power spectra (delta, theta, alpha, beta) as well as mean arterial blood pressure (MAP) and heart rate (HF) were measured at the following end-points: before the induction of anesthesia (control), 1 and 10 minutes after laryngoscopy and intubation (L & I). Linear regression analysis was computed to determine which of the EEG power spectra was most sensitive to detect insufficient blockade of nociceptive-related arousal when correlated with haemodynamics. In the fentanyl group the change in HF closely correlated with the decrease of power in the slow delta- and theta-domain (r2 = 0.98 and r2 = 0.89 respectively) of the EEG. The change in MAP also closely correlated with a decrease in the slow delta- and theta-domain (r2 = 0.97 and r2 = 0.99 respectively). There was little correlation in regard to spectral edge frequency (SEF) and HF and MAP changes (r2 = 0.36 and r2 = 0.12 respectively). In the sufentanil group the change in HF correlated closely with an increase of power in the fast alpha and a decrease in the slow theta-domain (r2 = 0.91 and r2 = 0.98 respectively) of the EEG. The changes in MAP closely correlated with an increase in the fast alpha-band a decrease in the slow theta-domain (r2 = 0.98 and r2 = 0.73 respectively). Also there was little correlation of SEF with HF and MAP changes (r2 = 0.09 and r2 = 0.02 respectively). Among the EEG-spectra, reduction of power in the slow delta- and theta-bands are the most sensitive parameters to determine insufficient antinociception of opioids commonly used for the induction in cardiac anesthesia. Increase of power in the alpha-band seems to be closely correlated with cortical reactivation and reduction of hypnosis, while a reduction of power especially in the deltabut more so in the theta-band of the EEG reflects nociception related arousal.

[Somatosensory evoked potentials (SEP) by isoflurane and enflurane in cardiosurgical interventions]. / Somatosensorisch-evozierte Potentiale (SEP) unter Isofluran und Enfluran bei kardiochirurgischen Eingriffen.

In the order to gain further insight into the sensory nervous pathways during enflurane- and isoflurane anaesthesia, two different concentrations (1 and 2 vol.%) of the anaesthetics were given to patients during extracorporeal circulation in normothermia and normocarbia, while somatosensory-evoked potentials (SEP) were recorded. As SEP-changes either reflect a change in functional integrity of the sensory nervous pathways (amplitude suppression) and a change in the speed of conduction (latency changes), the central effects of the volatile anaesthetics could be more fully evaluated. Isoflurane as well as enflurane induced a concentration-related change in latency especially of the late N100-component. However, in contrast to isoflurane administration the isomer enflurane in the high concentration range (2 vol.%) induced an increase of amplitudes of the early N20 and late N100-peak. Such an increase in amplitudes is interpreted as a disinhibition of medullary inhibitory centres, a possible premonitory sign of epileptogenic cortical activity, which already had been observed by various investigators.

[Cardiac pacemaker in the perioperative phase]. / Herzschrittmacher in der perioperativen Phase.

The anaesthesiologist is faced with a growing number of patients in need of cardiac pacing with systems of increasing complexity. This includes patients seen for de novo pacemaker implantation, patients with permanent pacemakers in place or patients requiring temporary pacing as an emergency or after cardiac surgery. This review article is intended to provide the anaesthesiologist with the information necessary to evaluate and treat such patients. Emphasis is laid on haemodynamic problems and possible pacemaker failure due to electromagnetic interference.

Enflurane in cardiac surgery.

Due to its advantageous properties the volatile anesthetic enflurane is used as the main agent for all routine open heart cases in our department. The technique consists of the induction of the heavely premedicated patient with fentanyl (10 micrograms/kg i.v.) followed by pancuroniumbromide (100 micrograms/kg i.v.). For the maintenance of anesthesia, i.e. before, during, and after cardio-pulmonary bypass, enflurane together with nitrous-oxide (up to 66%) is used, in a concentration between 1.0-2.0 vol%. Compared to other volatile anesthetics we foster a technique with enflurane because it has following advantages: 1. Less negative inotropic effect on the myocardium. 2. Less tendency for ventricular arrhythmia. 3. Fast onset of action. 4. Fast recovery from the anesthetic state. 5. Spontaneous post-operative respiration. 6. Lesser incidence of toxic hepatitis (Acta anaesth. belg., 1982, 33, 141-155).