Effect of Epidural Analgesia on Burst Suppression

Postoperative delirium (POD) is an acute cognitive disorder characterized by inattention, disorganized thinking, and a fluctuating course that develops over hours or days. Although delirium depends on the type of surgery, it is a common postoperative complication with an incidence of 10%-70%. POD causes an increase in mortality, morbidity and health care costs. Risk factors for POD; age, type and duration of surgery, inadequate pain control, type of anesthesia, anemia, transfusion, and preoperative cognitive impairment. In recent years, it has been emphasized that POD can be reduced with the widespread use of electroencephalogram (EEG) based anesthesia management and optimization of anesthetic drugs according to EEG patterns. EEG consists of 6 waveforms: slow, delta, theta, alpha, beta and gamma. Behavioral and neurophysiological patterns caused by anesthetic drugs are associated with different electroencephalogram waveforms. Recent developments in the introduction of EEG-based monitors have made significant contributions to the understanding of the fundamental changes in brain activity caused by anesthetic agents. Today, there are EEG-based anesthesia depth monitors such as bispectral index (BIS) (Medtronic, USA) or Sedline (Masimo Irvine CA). These monitors make it easier to optimize the depth of anesthesia with the numerical data obtained as a result of some calculations as well as the raw EEG. The burst suppression (BS) pattern on the EEG shows a decrease in brain neuronal activity and metabolic activity. Burst suppression can be induced by anesthetic drugs that modulate γ-aminobutyric acid type A receptors. Although sometimes deliberately induced for therapeutic purposes to treat refractory status epilepticus or increased intracranial pressure, burst suppression is generally considered potentially harmful and should be avoided.Studies conducted in recent years have shown the relationship between intraoperative burst suppression (BS) and POD. POD; It can be reduced by continuous EEG monitoring, reducing the dose of propofol, preferring regional anesthesia, effective postoperative pain control, early mobilization, and early postoperative discharge. Interventions that can reduce the development of postoperative delirium will be important for public health. Epidural analgesia can be used effectively in perioperative analgesia. It has been reported in the literature that epidural analgesia combined with general anesthesia reduces the amount of hypnotic drug required to achieve similar depth of anesthesia compared to general anesthesia alone. There is no study in the literature on whether the combination of epidural analgesia and general anesthesia reduces BS in EEG-based anesthesia applications. Our primary aim in this study is to evaluate whether the combination of general anesthesia and epidural analgesia reduces BS in EEG-based anesthesia in patients undergoing total hip and knee arthroplasty.