Time course of changes in cerebral blood flow velocity after tourniquet deflation in patients with diabetes mellitus or previous stroke under sevoflurane anesthesia

Perioperative care of patients with recent stroke undergoing nonemergent, nonneurological, noncardiac, nonvascular surgery: a systematic review and meta-analysis

PURPOSE OF REVIEW

To systematically review and perform a meta-analysis of published literature regarding postoperative stroke and mortality in patients with a history of stroke and to provide a framework for preoperative, intraoperative, and postoperative care in an elective setting.

RECENT FINDINGS

Patients with nonneurological, noncardiac, and nonvascular surgery within three months after stroke have a 153-fold risk, those within 6 months have a 50-fold risk, and those within 12 months have a 20-fold risk of postoperative stroke. There is a 12-fold risk of in-hospital mortality within three months and a three-to-four-fold risk of mortality for more than 12 months after stroke. The risk of stroke and mortality continues to persist years after stroke. Recurrent stroke is common in patients in whom anticoagulation/antiplatelet therapy is discontinued. Stroke and time elapsed after stroke should be included in the preoperative assessment questionnaire, and a stroke-specific risk assessment should be performed before surgical planning is pursued.

SUMMARY

In patients with a history of a recent stroke, anesthesiology, surgery, and neurology experts should create a shared mental model in which the patient/surrogate decision-maker is informed about the risks and benefits of the proposed surgical procedure; secondary-stroke-prevention medications are reviewed; plans are made for interruptions and resumption; and intraoperative care is individualized to reduce the likelihood of postoperative stroke or death.

A study of optimal concentration range and time window of sevoflurane preconditioning for brain protection in MCAO rats

Background

Sevoflurane preconditioning improves brain function in MCAO rats, and there are several methods for determining appropriate concentration and time windows for preconditioning. This study investigated the brain protective effects with a single sevoflurane preconditioning at different concentrations and different time windows on MCAO rats.

Methods

Adult Sprague-dawley rats were randomly assigned to 14 groups. The rats in the sevoflurane preconditioning group inhaled 0.5 MAC, 1.0 MAC, and 1.3 MAC sevoflurane, respectively for 3 h, and then MCAO models were established at 6 h, 12 h, 24 h, and 48 h. MCAO and sham groups underwent no preconditioning with sevoflurane. The neurological severity score, cerebral infarct volume and brain water content of the rats were measured 24 h after reperfusion.

Results

After inhalation of 1.3 MAC sevoflurane for 3 h of preconditioning, the MCAO model was established after 24 h. This preconditioning improved the neurological severity score, reduce cerebral infarct volume and brain water content in MCAO rats. After inhalation of 1.0 MAC sevoflurane for 3 h of preconditioning, MCAO model established after 24 h reduced the cerebral infarct volume and brain water content of MCAO rats, but the neurological severity score showed no significant improvement, and no significant brain protective effects were observed at other concentrations and time windows.

Conclusions

These results suggested that after inhalation of 1.3 MAC sevoflurane for 3 h of preconditioning, MCAO model established after 24 h demonstrated significant brain protective effects in MCAO rats.

The effect of focal cerebral ischemia-reperfusion injury on TLR4 and NF-κB signaling pathway

The present study analyzed the change of Toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) expression in focal cerebral ischemia-reperfusion injury model. A sample of 36 Sprague-Dawley rats were randomly selected and divided into sham operation group (group S), control group (group C) and Chrysanthemum ester group (NF-κB inhibitor, group CE), each group consisted of 12 rats. The rat model of focal cerebral ischemia-reperfusion was established. The physiological indexes and neurological severity score of rats was recorded by a double-blind method. The cerebral infarction area was evaluated by triphenyltetrazole oxide (TTC) staining on brain slices. Apoptosis was evaluated by TUNEL staining. Semi-quantitative PCR and western blot analysis was used to measure the expression of TLR4 and NF-κB. The neurological severity score of rats in group C and CE were found to be significantly lower than group S (P<0.01). The TTC staining results showed that group C and CE had different levels of cerebral infarction but the area of infarction in group CE was significantly lower than group C (P<0.01). In addition, the number of TUNEL positive cells in group CE was significantly lower than group C (P<0.01). Semi-quantitative PCR and westernblot analysis results showed that the expression of NF-κB and TLR4 of group S was significantly lower than that of group C and group CE (P<0.01), the relative expression of NF-κB and TLR4 of group CE was significantly lower than that of group C (P<0.01). Moreover, the expression of NF-κB p65/p50 of group CE and group C was significantly higher than that of group S (P<0.01). This study concludes that the focal cerebral ischemia-reperfusion injury in rats can cause brain damage and cell apoptosis. This effect might be associated to the increased expression of NF-κB and TLR4, and the activation of TLR4/NF-κB signaling pathway.

Effects of sevoflurane on rats with ischemic brain injury and the role of the TREK-1 channel

The purpose of this investigation was to determine the effects of sevoflurane on rats with ischemic brain injury and to determine the potential role of the TREK-1 channel in this process. Normal rats were randomly divided into three groups: Sham operation, sevoflurane anesthesia or chloral hydrate anesthesia group, an additional group of TREK-1 knockout rats were also studied. Semi-quantitative PCR and western blot analysis confirmed the lack of TREK-1 expression in the brain of TREK-1 knockout rats. The thread-tie method was used to establish middle cerebral artery occlusion (MCAO) model to induce cerebral ischemic brain injury. All rates were treated for 4 days prior to ischemia (for 2 h) followed by a 24 h reperfusion period. Physiological indexes of rats in each group both prior to and after surgery showed no statistical difference (P>0.05). Neurological function was scored both before (no statistical difference) and after surgery where it was found to be significantly better (lower score) in the sevoflurane anesthesia group than in chloral hydrate anesthesia and TREK-1 knockout groups (P<0.01). The area of cerebral infarction was measured by triphenyl tetrazolium chloride staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay to detect the apoptosis of brain cells. TTC staining showed different degrees of cerebral infarction in the various groups; the area of cerebral infarction in sevoflurane anesthesia group was significantly lower than that in chloral hydrate anesthesia and TREK-1 knockout groups (P<0.01). TUNEL assay showed that the number of TUNEL-positive cells was significantly lower in sevoflurane anesthesia group than in TREK-1 knockout and chloral hydrate anesthesia groups (P<0.01). In conclusion, results from this investigation showed that sevoflurane can protect the nerve function of rats with cerebral ischemic brain injury possibly by affecting the expression of proteins involved in the TREK-1 signaling pathway.