The effect of dexmedetomidine on electrocorticography in patients with temporal lobe epilepsy under sevoflurane anesthesia.

BACKGROUND: Although dexmedetomidine is often used in neuroanesthesia and neuronal critical care practice, its effect on cerebral electrical activity in those with an abnormal electroencephalogram is not known. The electrocorticogram (ECoG), a sensitive method for examining the effect of drugs on cerebral electrical activity and surgical treatment for epilepsy, is usually guided by monitoring of the ECoG. We investigated the effect of dexmedetomidine on ECoG in patients with epilepsy undergoing surgery with sevoflurane. METHODS: Patients with medically intractable temporal lobe epilepsy undergoing resection of the epileptic foci (n = 11) were enrolled. Under general anesthesia with 2.5% sevoflurane and end-tidal carbon dioxide tension at 30 mm Hg, ECoG was recorded by strip electrodes with eight contacts placed on the mesial temporal lobe ipsilateral to the epilepsy foci. Dexmedetomidine was given as a computer-controlled infusion to achieve target plasma concentrations of 0.5 and 1.5 ng/mL. Each concentration was maintained for 20 min and ECoG was recorded before infusion of dexmedetomidine and between the 10th and 20th min after starting infusion. The median frequency of ECoG, spectral power density of each spectral band, and number of spikes at each concentration of dexmedetomidine were compared by Kruskal-Wallis test, followed by Student-Newman-Keuls test. RESULTS: The median frequency of ECoG in 88 leads from all leads from all patients was significantly decreased by 1.5 ng/mL of dexmedetomidine compared with those at baseline and 0.5 ng/mL (P = 0.003 and 0.03, respectively); however, spectral power densities in the frequency bands: delta (<4 Hz), theta (> or =4 and <8 Hz), alpha (> or =8 and <13 Hz), and beta (> or =13 Hz), were not changed. Neither the number of leads with spikes nor the number of spikes in all leads and in the lead with highest number of spikes at baseline was affected by dexmedetomidine. CONCLUSIONS: Dexmedetomidine at plasma concentrations of 0.48 and 1.60 ng/mL decreased the median frequency of ECoG, but did not affect spike activity in patients with temporal lobe epilepsy anesthetized with 2.5% sevoflurane.

Early continuous venovenous hemodialysis in dialysis-dependent patients after cardiac surgery: safety and efficacy.

OBJECTIVES: The present study assessed the safety and efficacy of continuous venovenous hemodialysis (CVVHD) early after cardiac surgery. DESIGN: Retrospective database and medical record review. SETTING: University teaching hospital. PARTICIPANTS: Forty-five dialysis-dependent patients who underwent cardiac surgery with cardiopulmonary bypass. INTERVENTIONS: CVVHD was begun postoperatively after confirmation of hemostasis, irrespective of circulatory status. In the last 5 patients, the ratio of extravascular lung water (EVLW) to intrathoracic blood volume (ITBV) was measured using a single-indicator thermodilution catheter and compared with patients of normal renal function undergoing cardiac surgery. MEASUREMENTS AND MAIN RESULTS: CVVHD was started at 4 hours after ICU admission. The maximum decrease in blood pressure within 60 minutes after initiation of CVVHD was 11 +/- 9 mmHg in the unstable hemodynamics group (defined as patients who required continuous intravenous adrenaline or intra-aortic balloon pump on admission to the ICU [n = 15]) and 7 +/- 8 mmHg in the stable hemodynamics group (n = 30, not significant). Circulatory status and oxygenation improved significantly 12 hours after CVVHD initiation in the unstable hemodynamics group. Blood volume from the chest tube did not increase after CVVHD. Early mortality (2.2%) was lower than that reported previously. The EVLW/ITBV ratio after ICU admission in dialysis-dependent patients was significantly higher than in patients with normal renal function. CONCLUSIONS: Early CVVHD after cardiac surgery in dialysis-dependent patients was safe and effective. There was no associated increased postoperative bleeding or hemodynamic instability. Fluid removal improved respiratory status, particularly in patients requiring circulatory assistance, and overall early morality rates were lower that those previously published.

[The use of questionnaires for rotating residents in evaluating training in anesthesiology].

BACKGROUND: We prepared questionnaires for the rotating residents during their assignment for anesthesiology in the novel Japanese residency programs for the year 2004. METHODS: Questionnaires consisting of 39 items with 235 model answers for these items were prepared. The residents underwent three interviews by these questionnaires over the three-month training period. The number of correct answers for these questionnaires was recorded and evaluated using a computer database software. RESULTS: There was no significant correlation between the results of these questionnaires and the subjective evaluation by supervisors conducted during clinical training. On stepwise regression analysis, the results of the questionnaires for "American Society of Anesthesiologists Physical Status", "contraindications for epidural anesthesia", "complications of general anesthesia" and "initial procedures for patients in the operating room" correlated with the subjective evaluation by supervisors. CONCLUSIONS: Stepwise regression analysis was shown to be helpful in improving the questionnaires regarding the training in anesthesiology.

Duration of dialysis is a significant predictor of prolonged postoperative mechanical ventilation in dialysis-dependent patients undergoing cardiac surgery.

Prolonged mechanical ventilation is reported to correlate with increased risk of mortality after cardiac surgery. We designed the present study to determine the preoperative and intraoperative risk factors that could predict postoperative prolonged mechanical ventilation in dialysis-dependent patients undergoing cardiac surgery with cardiopulmonary bypass. Forty-four dialysis-dependent patients were divided into two groups; patients of group E were tracheally extubated within 24 h after admission to the intensive care unit postoperatively (n = 19) and patients of group L (n = 25) required more than 24 h of mechanical ventilation. All patients received hemofiltration during cardiopulmonary bypass and continuous veno-venous hemodialysis postoperatively. A multiple logistic regression analysis showed that duration of dialysis (>10 yr) and duration of surgery (>8 h) were independent risk factors of prolonged mechanical ventilation (>24 h). On admission to the intensive care unit, Pao2/Fio2 of group L was significantly lower than that of group E (294 +/- 135 versus 415 +/- 99 mm Hg) and the circulatory status of group L was worse than that of group E. The median (interquartile range) duration of intensive care unit stay in group E was 3 (3.00) days, which was significantly shorter than that of group L (5 [2.75] days). It is possible that longer surgery increases the likelihood of cardiac dysfunction and poor oxygenation in patients with a long history of dialysis.

Cesarean section at 28 weeks' gestation with resection of pheochromocytoma: perioperative antihypertensive management.

Pregnancy complicated by pheochromocytoma is potentially fatal. Pregnancy and labor increase the risk of hypertensive crisis as it may occur with the sudden release of catecholamine accompanying uterine contractility and straining. However, antepartum diagnosis reduces both maternal and fetal mortality, allowing for safe cesarean section and resection of tumor. We describe the management of perioperative hypertension for combined cesarean section and pheochromocytoma resection.

Dexmedetomidine decreases the convulsive potency of bupivacaine and levobupivacaine in rats: involvement of alpha2-adrenoceptor for controlling convulsions.

Dexmedetomidine, a highly selective alpha(2)-adrenoceptor agonist, is used in combination with local anesthetics for sedation and analgesia. We tested the hypothesis that dexmedetomidine used for sedation alters the convulsive potency of racemic bupivacaine and levobupivacaine in awake, spontaneously breathing rats. In the first experiments, male Sprague-Dawley rats were randomly divided into six groups: bupivacaine with no dexmedetomidine (bupivacaine control; BC), bupivacaine with small-dose dexmedetomidine (BS), bupivacaine with large-dose dexmedetomidine (BL), levobupivacaine with no dexmedetomidine (levobupivacaine control; LC), levobupivacaine with small-dose dexmedetomidine (LS), and levobupivacaine with large-dose dexmedetomidine (LL) (n = 10 for each group). Continuous infusion of dexmedetomidine (Groups BC and LC, 0 microg x kg(-1) x h(-1); Groups BS and LS, 3.6 microg x kg(-1) x h(-1); and Groups BL and LL, 10.8 microg x kg(-1) x h(-1)) was started after bolus injection (Groups BC and LC, 0 microg/kg; Groups BS and LS, 0.5 microg/kg; and Groups BL and LL, 1.5 microg/kg). Fifteen minutes after the start of the dexmedetomidine infusion, continuous infusion of bupivacaine (Groups BC, BS, and BL) or levobupivacaine (Groups LC, LS, and LL) at 1 mg x kg(-1) x min(-1) was started and continued until tonic/clonic convulsions occurred. Dexmedetomidine achieved significantly different sedation levels both in Groups BC, BS, and BL and in Groups LC, LS, and LL (P < 0.05). Convulsive doses of bupivacaine and levobupivacaine were significantly larger in Groups BL and LL than in Groups BC and LC, respectively (P < 0.01 for both). Concentrations of bupivacaine and levobupivacaine in plasma and in brain at the onset of convulsions were also larger in Groups BL and LL than in Groups BC and LC (P < 0.01 for both). In the second experiment, yohimbine (1 mg/kg) administered 10 min before and 5 min after the start of dexmedetomidine infusion completely reversed the sedative effect of dexmedetomidine (bolus 1.5 microg/kg, followed by 10.8 microg x kg(-1) x h(-1)). Convulsive doses and plasma and brain concentrations of bupivacaine and levobupivacaine at the onset of convulsions in rats receiving yohimbine and dexmedetomidine were significantly smaller than in those receiving only dexmedetomidine (P < 0.05 for all) and were similar to those without dexmedetomidine or yohimbine. We conclude that dexmedetomidine used for sedation decreases the convulsive potency of both bupivacaine and levobupivacaine in rats. Alpha(2)-adrenoceptor agonism may be involved in this anticonvulsant potency.