Monitoring: Equipment and Computers
Background: Several studies have been published, showing that a number of postoperative outcome parameters depend on the level of anaesthesia and analgesia during surgery. This study is a database study where the EEG data recorded and published previously (1) were analyzed using the qCON level of consciousness algorithm (Quantium Medical, Barcelona, Spain). The objective of the study was to evaluate a possible relation between the depth of anaesthesia assessed with the qCON and the consumption of morphine postoperatively.
Methods: This database study was prospective, observer blinded and included 50 women scheduled for elective abdominal hysterectomy. Anaesthesia was induced using propofol and remifentanil. Before leaving the recovery room the patients were provided with a programmed patient-controlled pump (PCA), which was only activated on demand. The EEG were registered from just before induction of anaesthesia and during the whole procedure, but the anaesthesiologist did not have access to the monitor.
Results: Seven patients were exluded from the study. The 43 patients who complied with the protocol were divided into two groups: Group High (n=12) with a mean qCON>55 of the registration time and Group Low (n=31) with a mean qCON< 55. Group High had significantly higher opioid requirements (0.23(0.05) mg/kg vs 0.17(0.1) mg/kg ) in the recovery and activated the PCA-pump more frequently during the first 24 postoperative hours. The reduction in morphine consumption was 25 %.
Conclusion: The results indicate that the peroperative depth of anaesthesia assessed with the qCON may reduce the postoperative analgesic requirements. A more advanced model using features extracted from the qCON index may lead to a more precise prediction of the opioid consumption, rather than only high and low.
1. Peroperative depth of anaesthesia may influence postoperative opioid requirements. Henneberg SW, Rosenberg D, Weber Jensen E, Ahn P, Burgdorff B, Thomsen LL. Acta Anaesthesiol Scand.2005 Mar;49(3):293-6.