Temporal profiles of aquaporin 4 expression and astrocyte response in the process of brain damage in fat embolism model in rats.

PURPOSE: Fat embolism syndrome is a serious complication observed after trauma, orthopedic surgery, and cardiac surgery. We investigated brain damage in relationship to temporal profiles of water channel aquaporin 4 (AQP4) and astrocyte response to fat embolism in rats. METHODS: Triolein (2 microl) was injected into the right internal carotid artery in rats. Neurological outcome (score: range, 0-5 = no deficit-dead), brain water content, histopathology, and immunohistochemistry for AQP4 and glial fibrillary acidic protein (GFAP) were evaluated at 2 h (2 h group, n = 12), 24 h (24 h group, n = 12), and 72 h (72 h group, n = 12) after triolein injection. Saline was injected in the control (C) group (n = 12). RESULTS: Neurological deficit score (median score of 2) and brain water content (mean value, 86.2%) increased significantly at 2 h with no progressive increase over 72 h. Damaged tissues with shrunken and triangular-shaped neurons with vacuole degeneration in cytoplasm and halo formation were distributed mainly, but not exclusively, to the ipsilateral hemisphere and were associated with increase in infiltration of inflammatory cells during the time course. Increases in immunostaining for AQP4 and GFAP were observed in the peri-affected region but not in the core. Reactive astrocytes with hypertrophy and dendrite elongation were detected at 72 h in the peri-affected region. CONCLUSION: The results suggest that brain damage with edema is induced very rapidly after triolein injection in association with increase in AQP4 expression and GFAP in the peri-affected region.

Infusion rate of propofol and jugular venous oxygen saturation.

We compared jugular venous blood oxygen saturation (Sj(O) (2)) and the arterial-to-jugular-bulb venous oxygen content difference (AjD(O) (2)) between bispectral index (BIS) values of 40 and 60, adjusted by the infusion rate of propofol. Eighteen postoperative neurosurgical patients (Glasgow Coma Scale [GCS] scores, 11-15) were enrolled. Normocapnia, normothermia, and a mean arterial blood pressure greater than 70 mmHg were maintained. At BIS values of 40 and 60, hemoglobin, oxygen saturation, and the oxygen partial pressure of arterial and jugular venous blood were measured. Sj(O) (2) at BIS40 (58 +/- 9%) was significantly (P < 0.01) lower than that at BIS60 (63 +/- 10%), and AjD(O) (2) at BIS40 (6.3 +/- 1.5 ml.dl(-1)) was significantly (P < 0.01) higher than that at BIS60 (5.7 +/- 1.5 ml.dl(-1); mean +/- SD). At BIS40, status defined as Sj(O) (2) less than 50% was observed in 3 patients, while this status was observed in 1 patient at BIS60. In conclusion, in patients with postoperative neurosurgical surgery (GCS scores, 11-15), decreases of propofol infusion to adjust the BIS value from 40 to 60 increase the cerebral oxygen balance.

[Anesthetic management of a patient undergoing PTA stent placement for right common carotid artery stenosis].

A 60-year-old man underwent percutaneous transluminal angioplasty (PTA) stent replacement of the right common carotid artery. Preoperative angiogram revealed bilateral vertebral artery occlusion and 50% stenosis in contralateral internal carotid artery. Anesthesia was induced and maintained with fentanyl and propofol by TCI. rSO2, BIS and EEG were monitored. Moderate hypothermia (33-35 degrees C) was induced by concomitant use of milrinone. Edaravone, a novel free radical scavenger, and Sendai cocktail were administered before interruption of carotid flow. During 5 minutes of test occlusion by balloon, right rSO2 decreased from 61% to 49% and EEG showed slow waves with decreased amplitude. Therefore we decided to perform PTA and stenting separately. Right rSO2 decreased from 62% to 48% during PTA (6 min occlusion), while rSO2 decreased from 66% to 50% during stenting (7.5 min occlusion). EEG also showed the similar changes as observed during test occlusion. After the procedures, rSO2 and EEG recovered in a short time. Postoperative angiogram showed an improvement of carotid artery stenosis and intracranial vessels showed no branch occlusion. Patient was maintained hypothermic (35 degrees C) for 2 days after surgery. He recovered without additional neurological complications. We found that rSO2 was a useful, real-time and non-invasive method for evaluation of cerebral ischemia in our patient.

Changes in the bispectral index during intraabdominal irrigation in patients anesthetized with nitrous oxide and sevoflurane.

Surgical stimulation typically results in an activation of electroencephalographic activity. In some instances, painful stimulation in the presence of inadequate anesthesia results in a suppression of the electroencephalogram. This phenomenon has been referred to as a "paradoxical arousal." In our daily practice, we have noted a marked decrease in the bispectral index (BIS) with large delta waves during abdominal surgery when the abdominal cavity was irrigated with normal saline. In the present study, we sought to evaluate changes in BIS during intraabdominal irrigation. Eighteen ASA physical status I-II patients scheduled for elective abdominal surgery were enrolled in the study and allocated randomly to the control group (group C) or the fentanyl group (group F). Anesthesia was induced with 3 mg/kg of thiopental and was maintained with sevoflurane and 50% nitrous oxide. BIS, 95% spectral edge frequency (SEF95), and burst-suppression ratio were recorded using a BIS monitor. Near the end of the procedure, but before irrigation of the abdominal cavity, 1.5 microg/kg fentanyl was given IV to group F. There was no significant change in BIS or SEF95 in group F patients during subsequent irrigation of the abdominal cavity. In contrast, BIS and SEF95 decreased significantly after start of irrigation in group C patients. These data show that the stimulation occurring during intraabdominal irrigation might cause a paradoxical arousal response, as evidenced by a decrease in processed electroencephalographic parameters. Pretreatment with fentanyl suppressed these changes. Anesthesiologists should be aware of this paradoxical arousal response to avoid an inappropriate decrease in the anesthetic concentration in such situations.

Are serum S100beta proteins and neuron-specific enolase predictors of cerebral damage in cardiovascular surgery?

OBJECTIVE: To examine whether serum concentrations of S100beta protein and neuron-specific enolase (NSE) are predictors of cerebral damage in cardiovascular surgery. DESIGN: Prospective clinical study. SETTING: University hospital. PARTICIPANTS: Eighteen patients with conventional cardiopulmonary bypass (CPB), 7 with selective cerebral perfusion (SCP), and 3 volunteers (blood samples). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: S100beta and NSE were measured in the blood obtained at 7 time points during and after operation. The concentrations of these markers in the blood from the surgical field and the cell-saver device, and the influence of graded hemolysis (in vitro) on the concentrations of these proteins were also examined. The mean values of S100beta in the CPB group (2.08 +/- 2.00 ng/mL) and the SCP group (1.46 +/-0.77 ng/mL) were highest after aortic declamping and after termination of SCP, respectively. The mean values of NSE in the CPB group (29.1 +/- 14.0 ng/mL) and the SCP group (31.2 +/- 13.6 ng/mL) were highest after termination of CPB and at the end of the operation, respectively. Three patients suffered from cerebral complications, but the elevation of these markers during operation was indistinguishable from those in the other patients. Peak concentrations of S100beta protein in the CPB group and NSE in the SCP group were correlated with the duration of aortic cross-clamping and CPB, respectively. S100beta protein and NSE concentrations in the blood from the surgical field were significantly larger than those in arterial blood, whereas the concentrations in the blood in the cell-saving device were not elevated. The concentration of S100beta protein was not influenced by the extent of hemolysis, whereas NSE concentration was markedly elevated by hemolysis. CONCLUSION: A large part of the increases in S100beta protein and NSE during CPB and SCP is not attributed to neuronal damage, but to contamination with the blood from the surgical field. To determine whether these markers are useful to predict neurologic complications, it will be necessary to exclude contamination from the surgical field as observed in the present study.

[Efficacy of bispectral index monitoring in improving anesthetic management, economics, and use of the operating theater].

This study was designed to assess the efficacy of bispectral index (BIS) monitoring in reducing the amount of volatile anesthetics used and improving recovery profiles. Sixty patients (ASA physical status 1 or 2) undergoing various surgical procedures under sevoflurane/nitrous oxide anesthesia were studied. The patients were randomly assigned to two groups of which anesthesia was carried out with (BIS group) or without (control group) monitoring BIS, and in the latter, anesthesiologist was blinded to the BIS values. In the BIS group, sevoflurane concentration was adjusted to achieve target BIS values between 40-60 during surgery and 60-75 during the final 15 min of the surgery. Drug usage, incidence of intraoperative complications, and recovery parameters were recorded. Demographics were similar between the groups. The BIS values in the BIS group were significantly higher compared with those of control group in which BIS values were blinded during anesthesia. The sevoflurane consumption in the BIS group (17 +/- 3 ml.h-1) was lower than control group (22 +/- 3 ml.h-1). Compared with control group, the patients in BIS group were extubated earlier and became eligible for discharge earlier from recovery room than control group. There was no significant difference in the incidence of intraoperative complications between the groups. Titrating sevoflurane concentration with BIS monitoring during anesthesia decreased anesthetic consumption and improved recovery compared with standard clinical practice.