Spectral Analysis of EEG with Reversible Middle Cerebral Artery Occlusion in Rats / 대한마취과학회지

BACKGROUND: An adequate cerebral blood flow is critical in maintaining obligatory metabolic function of cerebral neurons. The occlusion of these flows may cause impairment of the cellular metabolic function. Therefore, the early detection and treatment of this can have a direct impact on the prognosis. This study is designed to determine the changes of electroencephalography (EEG) waves with power spectral analysis during and after cerebral blood flow impairment with reversible middle cerebral artery occlusion in rats. METHODS: Five rats were anesthetized with ketamine and the left middle cerebral artery was reversibly occluded. Neurologic deficit and the EEG were evaluated. The principal procedure consisted of the following: All branches of the external carotid artery and pterygopalatine artery of the internal carotid artery were interrupted. At this point, the internal carotid artery is the only branch of the common carotid artery. Afterwards, the external carotid artery was interrupted. A 4-0 monofilament nylon suture, its tip rounded, was introduced into the external carotid artery lumen and advanced to block blood flow into the middle cerebral artery. The suture was withdrawn to permit reperfusion after 2 hours. Monitoring of the EEG was performed before the occlusion, after 10, 30, 60, and 120 minutes of occlusion, and after 10, 30 and 60 minutes of reperfusion. The neurologic findings were scored on a five-point scale. RESULTS: In the spectral power analysis of EEG, the total power of the EEG amplitude decreased significantly after left middle cerebral artery occlusion, increased after 30 minutes of occlusion, and decreased significantly after reperfusion. The theta, alpha and beta waves changed significantly after occlusion. Theta and beta waves were reversed slowly. After reperfusion, theta and alpha waves decreased significantly. CONCLUSIONS: It is suggested that the spectral analysis of an EEG is useful in early detection and treatment of ischemia in patients with cerebrovascular disease.

EEG and Topographic Frequency Analysis of Laser Therapeutic Efficacy in Occipital Headaches / 대한마취과학회지

BACKGROUND: It is controversial that an electrocardiography (EEG) is valuable in evaluation of patients with headache. The purpose of this study was to determine whether EEG brain mapping can be a useful indicator for evaluating the analgesic efficacy of treatment on the patient with an occipital headache. METHODS: We did an EEG on 20 patients with occipital headaches at the peri-laser application period. The laser was radiated for 3 minutes a third of the total distance from the external occipital protuberance to the mastoid process on the superior nuchal line. An EEG was taKen before laser radiation as control use, and at 10, 30 and 60 minutes after laser radiation by 32 channel electrodes (international 10 20 system). The EEG mapping was red for the high electric potential and blue for the low electric potential. RESULTS: Compared with control group, the alpha wave increased significantly in parieto-occipital and occipital region at 60 minutes after laser radiation (P < 0.05). DarK red color was increased especially in occipital region at 60 minutes after laser radiation, compared with EEG mapping before laser radiation. Good and Fair improvements were observed in 55% of the patients with occipital headaches. CONCLUSIONS: We conclude that EEG can be a valuable indicator in the evaluation of analgesic efficacy of treatment in the patients suffering from occipital headaches. Pain scores were assessed by the patient with the visual analogue scale (VAS).

The Efficacy of Electroencephalography and Somatosensory Evoked Potential Monitoring for Detecting Cerebral Ischemia during Carotid Endarterectomy under Regional Anesthesia / 대한마취과학회지

BACKGROUND: Carotid endarterectomy has been proven to be beneficial for the prevention of strokes in both symptomatic and asymptomatic patients with significant carotid stenosis. Even if there is no consensus as to the most appropriate monitoring method for detecting cerebral ischemia during carotid endarterectomy, electroencephalography (EEG) and/or somatosensory evoked potential (SSEP) has been extensively used to evaluate cerebral functions. We estimated the efficacy of EEG and SSEP for detecting cerebral ischemia during carotid endarterectomy in conscious patients. METHODS: One or both of 16-channel EEG and SSEP monitoring were performed in 103 patients scheduled for carotid endarterectomy under cervical plexus block. We estimated the sensitivity and specificity of EEG and SSEP for detecting cerebral ischemia expressed by altered consciousness and shunt insertion. RESULTS: During carotid clamp in 74 cases studied, significant EEG changes were noted in 5 of the 16 patients who had cerebral ischemia, however 11 patients had no EEG changes despite cerebral ischemia. During carotid clamp in 84 cases studied, significant SSEP changes were noted in 7 of the 19 patients who had cerebral ischemia, however 12 patients had no SSEP changes despite cerebral ischemia. The sensitivity and specificity for detecting cerebral ischemia were 31% and 86% for EEG and 37% and 95% for SSEP, respectively. CONCLUSIONS: We conclude that EEG and SSEP monitoring during carotid endarterectmy under regional anesthesia is not a sensitive method for detecting cerebral ischemia.

Anesthetic Management of Carotid Endarterectomy: A case report / 대한마취과학회지

Carotid endarterectomy is the preferred treatment for a patient with transient ischemic attacks (TIAs) in whom carotid artery stenosis is present. This patient was a 58-year-old male associated with 60 kg in body weight and 172 cm in height. He was scheduled for elective carotid endarterectomy in ASA physical status III. For premedication, he was administered triflupromazine (Veprin ) 10 mg and glycopyrrolate 0.2 mg IM 1 hour prior to induction. Induction was established with thiopental sodium, succinylcholine after preoxygenation. N2O/O2 (2:1), isoflurane and pancuronium were administered for maintenance. For monitoring, ECG, EEG, direct arterial pressure, ETCO2, CVP and rectal temperature were performed. A primary goal of the intraoperative management is the prevention of the cerebral ischemia. He was challenged to maintain adequate cerebral perfusion without causing myocardial ischemia. The EEG is the reliable indication of cortical function during general anesthesia. No signs of the cerebral ischemia were occurred at the time of the carotid occlusion. Minute ventilation was kept mild hypo-or normocapnia. He had no new neurologic deficits and myocardial ischemia, and discharged on 14 day postoperation.

Anesthetic Management of Carotid Endarterectomy: A case report / 대한마취과학회지

Carotid endarterectomy is the preferred treatment for a patient with transient ischemic attacks (TIAs) in whom carotid artery stenosis is present. This patient was a 58-year-old male associated with 60 kg in body weight and 172 cm in height. He was scheduled for elective carotid endarterectomy in ASA physical status III. For premedication, he was administered triflupromazine (Veprin ) 10 mg and glycopyrrolate 0.2 mg IM 1 hour prior to induction. Induction was established with thiopental sodium, succinylcholine after preoxygenation. N2O/O2 (2:1), isoflurane and pancuronium were administered for maintenance. For monitoring, ECG, EEG, direct arterial pressure, ETCO2, CVP and rectal temperature were performed. A primary goal of the intraoperative management is the prevention of the cerebral ischemia. He was challenged to maintain adequate cerebral perfusion without causing myocardial ischemia. The EEG is the reliable indication of cortical function during general anesthesia. No signs of the cerebral ischemia were occurred at the time of the carotid occlusion. Minute ventilation was kept mild hypo-or normocapnia. He had no new neurologic deficits and myocardial ischemia, and discharged on 14 day postoperation.

Anesthetic Management of Carotid Endarterectomy under EEG and SEP Monitoring / 대한마취과학회지

BACKGROUND: Carotid endarterectomy is a very high risk operation, combined with high incidence of stroke and myocardial infarction. We experienced 36 cases of carotid endarterectomies during the last two years. We reviewed these cases with anesthetic management and neurologic monitoring. METHODS: All of the operations were performed under general anesthesia. 33 cases were monitored by EEG and SEP. We maintained cerebral perfusion during cross-clamping and shunt by normothermia, normocarbia and mild hypertension. RESULTS: 33% of the patients had severe coronary artery stenosis and 41% had severe contralateral carotid artery stenosis preoperatively. During the operation, 10 patients showed transient EEG changes without SEP change or neurologic sequele. The major postoperative complication was myocarial infarction in one patient. There were 3 cases of postoperative cerebral infarction in radiologic findings. One case occurred after myocardial infarction and the other two cases showed no clinical evidence of neurologic deficit. CONCLUSIONS: In anesthetic management of carotid endarterectomy patients, maintaining cerebral perfusion, preventing perioperative myocardial infarction are important and monitoring neurologic function with EEG and SEP should be considered to prevent neurologic deficits.

Anesthetic Management for Carotid Endarterectomy: case report / 대한마취과학회지

We have experienced an anesthetic management of 56-year-old male patient with carotid stenosis. Carotid endarterectomy was performed with processed electroencephalography (compressed spectral array, CSA) monitoring. Carotid endarterectomy has significant risk of perioperative stroke and myocardial infarction. For brain protection during carotid cross clamp, body temperature of patient was maintained at 33.5oC and thiopental was infused continuously to induce burst suppression. To maintain blood pressure during cross clamp, dopamine was infused continuously and phenylephrine was injected intermittently. CSA was performed to monitor thiopental-induced burst suppression and ischemic brain insult. After releasing carotid cross clamp, body temperature was raised to 35oC.

EEG Spectral Analysis during Administation of Combined Inhalation Anesthetics in Rats / 대한마취과학회지

BACKGROUND: The electroencephalogram(EEG) has long been used to study the effects of anesthetic drugs on central nervous system function. This study was designed to evaluate the accuracy of two EEG parameters for assessing anesthetic depth during inhalation of 1.5 MAC three inhalation anesthetics (halothane, enflurane, and isoflurane) with 50%-N2O in rats. METHODS: Total 15 rats weighing between 300~350 g, with 5 rats for each anesthetic group were tested for investigation the anesthetic depth. EEG spectrum analysis was evaluated for three inhalation anesthetics which all were added with 50%-N2O. The spectral edge frequency(SEF), median power frequency(MPF) were obtained from the EEG spectrum analysis of raw EEG via fast Fourier transform(FFT). RESULTS: Raw EEG of halothane demonstrated sigmoidal shaped EEG, enflurane abundant spike waves, and isoflurane burst suppression. When 50%-N2O was added to each anesthetic group, the characteristics of the raw EEG were disappeared. EEG spectrum analysis enabled to distinguish the effects of each anesthetic on the anesthetic depth. EEG spectrum analysis demonstrated after 50%-N2O was added that the values of MPF and SEF were significantly decresed as 2.5 Hz and 6.5 Hz from 5.2 Hz and 14.2 Hz respectively. CONCLUSIONS: It is speculated that SEF and MPF was decreased due to the suppression of cerebral electrical activity. The decreases of SEF and MPF from analysis of EEG spectra confirm that the addition of 50%-N2O to each inhalation anesthetics enabled the deeper anesthetic depth.

Effects of Intravenous Anesthetics on EEG Spectral Analysis during Cesarean Section / 대한마취과학회지

BACKGROUND: Anesthesia induces the spectral changes in EEG. Attempts to relate these spectral changes to adequacy of anesthesia have been hindered due to the complex waveforms of EEG. The objective of this investigation is to monitor the awareness of patients during cesarean section by means of EEG spectral analysis. METHODS: 20 patients for cesarean section aged from 24 to 39 and ASA class I or II, were maintained with O2(50%)-N2O(50%)-enflurane(0.8%). And they were administered with midazolam(0.07 mg/kg) in group I(n=6), fentanyl(1 microgram/kg) in group II(n=7), and fentanyl(2 microgram/kg) in group III(n=7) after birth. The density of each spectral band in EEG (delta 1-3.25 Hz, theta 3.5-7.75 Hz, alpha 8-12.15 Hz and beta 13-31.75Hz) was analyzed to derive total density, delta ratio and median power frequency. RESULTS: The spectral data demonstrated that the alpha rhythm was dominant in pre-induction period and beta rhythm was abundant both in the immediate post-induction period and after birth for all three groups. Delta ratio and median power frequency decreased after injection of midazolam and fentanyl in all three groups. None of patients could recall the memory about experience during cesarean section. CONCLUSIONS: These findings indicate that EEG spectral analysis is potentially useful to determine the changes of cerebroelectrical activity but difficult to monitor the awareness of patients during cesarean section.