The effects of dexmedetomidine on liver ischemia-reperfusion injury in rats.

BACKGROUND: Ischemia-reperfusion (IR) injury of the liver may cause various types of damage to hepatic tissues. It can affect the prognosis of patients and the success of an operation. Dexmedetomidine is a selective α2 receptor agonist. We investigated whether dexmedetomidine provides protection against IR-induced liver injury in rats. METHODS: Forty rats were divided equally into four groups. In group 1, the liver was manipulated after the laparotomy, and no occlusion of the vessels of the liver was performed. In group 2, once the abdomen was opened, 60 min of ischemia and 60 min of reperfusion were applied according to the segmental hepatic ischemia model. In group 3, 10 µg/kg of dexmedetomidine was injected into the peritoneal cavity 30 min before ischemia. In group 4, 100 µg/kg of dexmedetomidine was injected into the peritoneal cavity 30 min before ischemia. Further procedures in groups 3 and 4 were the same as those of group 2. After the experiment was completed, the rats were killed. Liver tissues were removed and stored until biochemical and histologic assessments were performed. RESULTS: The malondialdehyde level in group 2 was higher than that of groups 1, 3, and 4 (P = 0.001, P = 0.000, and P = 0.000, respectively). Superoxide dismutase, catalase, and glutathione levels in group 2 were lower than those in group 1 (P = 0.001, P = 0.027, and P = 0.014, respectively). Superoxide dismutase and catalase levels in group 4 were higher than those in group 2 (P = 0.002 and P = 0.000, respectively). GSH levels in groups 3 and 4 were higher than those in group 2 (P = 0.049 and P = 0.006, respectively). A lower glutathione peroxidase level was detected in groups 2 and 3 than that in group 1 (P = 000). Group 4 demonstrated an increase in glutathione peroxidase levels compared with group 3 (P = 0.014). The histologic injury scores in groups 2-4 were higher than those in group 1 (P = 0.003, P = 0.002, and P = 0.001, respectively). However, the histologic injury scores were lower in groups 3 and 4 than those in group 2 (P = 0.003 and P = 0.002, respectively). CONCLUSIONS: This study showed that dexmedetomidine may protect the liver against IR injury in rats.

The effects of cognitive impairment on anaesthetic requirement in the elderly.

CONTEXT: Patients with dementia have a lower bispectral index score (BIS) when awake than age-matched healthy controls. OBJECTIVES: The primary aim was to compare the BIS and the dose of propofol required for induction in patients suffering from cognitive impairment with that in those who had normal cognitive function. This study also evaluated the effects of cognitive impairment in the elderly on anaesthetic agent consumption during surgery and on emergence from anaesthesia. DESIGN AND SETTING: This randomised controlled study was carried out in a university hospital. Patients over 65 years of age, ASA I-II and scheduled for elective orthopaedic procedures were allocated to one of two groups. INTERVENTIONS: Patients (n = 92) were allocated according to their Mini Mental State Examination score: 25 or higher (group 1) or 21 or less (group 2). All patients received propofol 0.5 mg kg(-1) following the commencement of a remifentanil infusion at 0.5 µg kg(-1) min(-1). After incremental doses of propofol up to loss of consciousness, a propofol infusion was started at 75 µg kg(-1) min(-1). Propofol and remifentanil infusion doses were adjusted to keep the BIS value between 45 and 60 during surgery. MAIN OUTCOME MEASURE: MMSE score was evaluated 24 h before and after surgery. The anaesthetic consumption, mean arterial pressure, HR and BIS values of the patients were recorded. RESULTS: Before surgery, mean Mini Mental State Examination scores were 26.8 ± 1.6 and 16.6 ± 4.2 in group 1 and 2, respectively. These returned to baseline value 24 h after surgery in group 1 (26.6 ± 1.5) and group 2 (15.6 ± 4.3). Before induction, four of 45 patients (8.9%) in group 1 had a BIS value less than 93 compared with 13 of 47 (27.7%) in group 2 (P = 0.02). The mean BIS value was significantly lower in group 2 than in group 1 before induction, during loss of consciousness, 3 and 5 min after discontinuation of the anaesthetic agents and before extubation (P < 0.05). The induction dose of propofol was lower in group 2 than in group 1 (P = 0.02). The eye opening time was significantly longer in group 2 than in group 1 (P = 0.03). CONCLUSION: The baseline BIS value was lower in patients with cognitive impairment than in those with normal cognitive function. The former received less propofol during induction and eye opening time was longer. On the basis of our findings from the recovery period, we suggest that the recommended target BIS value for adequate anaesthesia in the general population is inappropriate for patients with cognitive impairment.

Sevoflurane as an alternative anaesthetic for electroconvulsive therapy.

OBJECTIVES: The aim of this study was to investigate the effects of sevoflurane and propofol used in electroconvulsive therapy (ECT) on hemodynamic variables and duration of seizure activity and recovery profiles. METHODS: Sixteen patients who were not premedicated, with a mean age 27.1 years, were enrolled in this prospective open trial, receiving a total of 64 ECT treatments. Each patient was given the following 2 anesthetic regimens in random order: In group S, anesthesia was induced with 7% sevoflurane in 100% oxygen at 6 L min fresh gas flow until the loss of consciousness and 1.5 mg kg propofol in group P. Adequate muscle relaxation was achieved with suxamethonium, 1.0 - 1.2 mg kg. Noninvasive mean arterial pressure (MAP) and heart rate (HR) values, duration of motor seizure activity, and recovery times were recorded. RESULTS: The mean motor seizure duration was significantly longer with sevoflurane (mean [SD]: 43.09 [16.6] s) than with propofol (28.91 [7.9] s; P < 0.05). The MAP 1 minute and 10 minutes after ECT (101.25 [7.5] mm Hg and 100.16 [11.0] mm Hg, respectively) was significantly increased compared with before ECT (94.56 [6.9] mm Hg) in sevoflurane group (P < 0.05). Time to spontaneous breathing, eye opening and obeying commands, and changes in MAP and HR during and after ECT were similar in both regimens. CONCLUSION: Induction with 7% sevoflurane allows prolonged duration of motor seizures in ECT. We concluded that induction of anesthesia with sevoflurane inhalation is a reasonable alternative for patients undergoing ECT.