Desflurane is risk factor for postoperative delirium in older patients' independent from intraoperative burst suppression duration.

Background: Postoperative Delirium (POD) is the most frequent neurocognitive complication after general anesthesia in older patients. The development of POD is associated with prolonged periods of burst suppression activity in the intraoperative electroencephalogram (EEG). The risk to present burst suppression activity depends not only on the age of the patient but is also more frequent during propofol anesthesia as compared to inhalative anesthesia. The aim of our study is to determine, if the risk to develop POD differs depending on the anesthetic agent given and if this correlates with a longer duration of intraoperative burst suppression. Methods: In this secondary analysis of the SuDoCo trail [ISRCTN 36437985] 1277 patients, older than 60 years undergoing general anesthesia were included. We preprocessed and analyzed the raw EEG files from each patient and evaluated the intraoperative burst suppression duration. In a logistic regression analysis, we assessed the impact of burst suppression duration and anesthetic agent used for maintenance on the risk to develop POD. Results: 18.7% of patients developed POD. Burst suppression duration was prolonged in POD patients (POD 27.5 min ± 21.3 min vs. NoPOD 21.4 ± 16.2 min, p < 0.001), for each minute of prolonged intraoperative burst suppression activity the risk to develop POD increased by 1.1% (OR 1.011, CI 95% 1.000-1.022, p = 0.046). Burst suppression duration was prolonged under propofol anesthesia as compared to sevoflurane and desflurane anesthesia (propofol 32.5 ± 20.3 min, sevoflurane 17.1 ± 12.6 min and desflurane 20.1 ± 16.0 min, p < 0.001). However, patients receiving desflurane anesthesia had a 1.8fold higher risk to develop POD, as compared to propofol anesthesia (OR 1.766, CI 95% 1.049-2.974, p = 0.032). Conclusion: We found a significantly increased risk to develop POD after desflurane anesthesia in older patients, even though burst suppression duration was shorter under desflurane anesthesia as compared to propofol anesthesia. Our finding might help to explain some discrepancies in studies analyzing the impact of burst suppression duration and EEG-guided anesthesia on the risk to develop POD.

Rhythmic electrographic discharges during deep hypothermic circulatory arrest.

OBJECTIVE: The main objective of this study is to examine the prevalence and timing of rhythmic electrographic discharges and periodic sharp transients during aortic arch repair surgeries using DHCA as detected by continuous intraoperative encephalogram (EEG) and correlate it with outcome. METHODS: Electronic medical records and the intraoperative EEGs of 32 patients who underwent aortic arch reconstruction with DHCA were reviewed. Preoperative patient characteristics, intraoperative data, and postoperative outcomes were examined. EEGs were graded based on the frequency of sharp transients (grade 0-2) and/or the presence of rhythmic electrographic discharges (grade 3). RESULTS: Periodic sharp transients were seen in 30/32 cases. Grade 1 and grade 2 activations were more prominent during cooling at nasopharyngeal temperature of 23.9±4.01 °C (mean±SDV). Rhythmic electrographic discharges occurred in seven patients and were exclusively seen during cooling at nasopharyngeal temperatures below 28 °C except in one case during rewarming at nasopharyngeal temperatures of 22°C. No patient with rhythmic discharges developed postoperative clinical neurologic deficit or seizures. CONCLUSIONS: Periodic sharp transients occurred in almost all cases during induction of deep hypothermia. This activity was not associated with postoperative neurologic deficit. SIGNIFICANCE: Clinical neurophysiologists, technicians and surgeons need to be aware that low amplitude periodic sharp transients and rhythmic electrographic discharges are common during DHCA, yet have no apparent clinical significance.

Intraoperative electroencephalography predicts postoperative seizures in infants with congenital heart disease.

BACKGROUND: During the surgical repair of infants with congenital cardiac defects, there can be periods of decreased cerebral blood flow, particularly during deep hypothermic circulatory arrest. As a result, these infants are at increased risk for seizures and long-term neurodevelopmental difficulties. METHODS: Thirty-two infants with congenital heart disease had continuous video-electroencephalographic (EEG) monitoring pre-, intra-, and postoperatively for 48 hours after surgery. RESULTS: For patients requiring deep hypothermic circulatory arrest (n = 17) the EEG pattern for all patients became suppressed and eventually isoelectric below 25 °C. Two of the 32 infants had electrical seizures within the 48-hour monitoring period. Both required deep hypothermic circulatory arrest, and the burst pattern during recovery had rhythmic, sharp components that were high amplitude and often asynchronous between the hemispheres. The interval between the onset of seizure activity and initiation of the sharp burst pattern during surgery was 29 and 40 hours. This pattern was not observed during isoelectric recovery from infants who did not develop postoperative seizures. CONCLUSIONS: The EEG in infants during deep hypothermic circulatory arrest displayed predictable changes. We identified an electroencephalographic pattern following the isoelectric period that may predict seizure development in the subsequent 48 hours.