Effects of propofol on lactate accumulation and oedema formation in focal cerebral ischaemia in hyperglycaemic rats

Randomized Trial to Compare Plasma Glucose Trends in Patients Undergoing Surgery for Supratentorial Gliomas under Maintenance of Sevoflurane, Desflurane, and Propofol

Background

Anesthetic agents influence the glycemic response by affecting the neuroendocrine surgical response or directly modifying pancreatic insulin release. Due to chances of neuronal damage, intraoperative hyperglycemia and hypoglycemia both are detrimental for patients undergoing neurosurgeries. Inhalational (sevoflurane and desflurane) and intravenous (propofol) agents have been found to raise intraoperative glucose levels in nonneurological surgeries.

Aim

We aimed to compare the intraoperative glucose levels in supratentorial glioma surgeries under the maintenance of three anesthetic agents such as sevoflurane, desflurane, and propofol.

Materials and Methods

This randomized trial was conducted with 90 nondiabetic adults with supratentorial glioma. Thirty patients were allocated randomly to the three groups receiving sevoflurane, desflurane, and propofol. Baseline and hourly plasma glucose levels were recorded. Postoperatively, the time required to achieve an Aldrete score of 9 and complications were assessed.

Results

Baseline plasma glucose levels were 111.23 ± 11.67, 109.47 ± 19.75, and 111.7 ± 13.88 mg/dL (P = 0.84) in sevoflurance, desflurane, and propofol group, respectively. All of them showed an elevation of plasma glucose in relation to the time of surgery with variable trends. In the 4^th and 5^th h, the elevations in the inhalational groups (sevoflurane and desflurane) were significantly higher than the propofol group (P = 0.003 and 0.002, respectively). The time for achieving Aldrete's score of 9 was higher in the propofol group (P < 0.0001). No differences were observed in the duration of hospital stay or complications.

Conclusions

Maintenance of anesthesia in nondiabetic patients showed clinically modest rise of plasma glucose which is higher in patients under sevoflurane and desflurane than under propofol. However, the immediate recovery was faster with inhalational agents compared to propofol-based anesthesia.

Metabolic reprogramming by the pyruvate dehydrogenase kinase-lactic acid axis: Linking metabolism and diverse neuropathophysiologies

Emerging evidence indicates that there is a complex interplay between metabolism and chronic disorders in the nervous system. In particular, the pyruvate dehydrogenase (PDH) kinase (PDK)-lactic acid axis is a critical link that connects metabolic reprogramming and the pathophysiology of neurological disorders. PDKs, via regulation of PDH complex activity, orchestrate the conversion of pyruvate either aerobically to acetyl-CoA, or anaerobically to lactate. The kinases are also involved in neurometabolic dysregulation under pathological conditions. Lactate, an energy substrate for neurons, is also a recently acknowledged signaling molecule involved in neuronal plasticity, neuron-glia interactions, neuroimmune communication, and nociception. More recently, the PDK-lactic acid axis has been recognized to modulate neuronal and glial phenotypes and activities, contributing to the pathophysiologies of diverse neurological disorders. This review covers the recent advances that implicate the PDK-lactic acid axis as a novel linker of metabolism and diverse neuropathophysiologies. We finally explore the possibilities of employing the PDK-lactic acid axis and its downstream mediators as putative future therapeutic strategies aimed at prevention or treatment of neurological disorders.

Influence of two anesthetic techniques on blood sugar level in head injury patients: A comparative study

BACKGROUND

Head injury presents a major worldwide social, economic, and health problem. Hyperglycemia is a significant indicator of the severity of injury and predictor of outcome, which can easily be prevented. There has been a long-standing controversy regarding the use of inhalational or intravenous (i.v.) anesthetic agents for surgery of head injury cases and impact of these agents on blood sugar level.

AIMS AND OBJECTIVES

The aim of this study is to find out anesthetic drugs and technique having minimal or no effect on the blood sugar, and Glasgow Coma Scale (GCS) of patients with a head injury by comparing two types of anesthetic techniques in surgery of head injury patients.

MATERIALS AND METHODS

This was a prospective, randomized, and comparative study, conducted on 60 adult head injury patients. The patients were divided into two groups of 30 each. Group I patients received induction with sevoflurane and then had O2 + air + sevoflurane for maintenance with controlled ventilation. Group II patients received induction with i.v. propofol and then had O2 + air + propofol for maintenance with controlled ventilation. Injection fentanyl was used in both the groups at the time of induction and in intermittent boluses in maintenance. In observation, blood sugar level and mean arterial pressure were assessed at different time periods perioperatively in both groups while GCS was analyzed pre- and post-operatively.

STATISTICAL ANALYSIS

Statistical analysis was performed by Microsoft Excel 2010 using t-test for comparison between the two groups and Z-test for comparison of proportions.

RESULTS AND CONCLUSION

Blood sugar level was found significantly higher in patients of sevoflurane group at 30 min after induction, at the end of surgery, and 1 h after the end of anesthesia than propofol group patients. This increase of blood sugar level did not have any significant alteration in the GCS profile of the patients in sevoflurane group as compared to propofol group patients. Nausea and vomiting were found more in sevoflurane group while hypotension and bradycardia were found more with propofol group.

The Effects of Propofol and Isoflurane on Blood Glucose during Abdominal Hysterectomy in Diabetic Patients

BACKGROUND

Acute hyperglycemia in the perioperative period is associated with significantly increased complications. In few human studies the effects of propofol and inhalational anesthetic on the glucose metabolism were compared. In this study we evaluated the effect of propofol and isoflurane on blood glucose during abdominal hysterectomy in diabetic patients.

METHODS

After approval by the Ethical Committee and written informed consent, thirty 35 to 65 years old diabetic women underwent for elective abdominal hysterectomy under general anesthesia were studied in this randomized single blind clinical trial study. The plasma glucose was maintained at 100 to 180 mg/dL during the operation. Anesthesia protocol was similar in two groups except maintenance of anesthesia that was with infusion of propofol in the propofol group and with isoflurane in the isoflurane group. Blood glucose level and the rate of insulin intake during surgery compared between two groups.

RESULTS

Mean blood glucose before induction of anesthesia did not have significant difference between two groups, but 60 and 90 minutes after starting the operation blood glucose in the propofol group was significantly lower than isoflurane group. Also with using Repeated Measure test, two groups was significantly different according to blood glucose (P=0.045). Mean of administration of insulin during the surgery did not have significant difference between two groups by using repeated measure test and P=0.271. Also mean of bispectral index in different times during the surgery between two groups didn't have significant difference (P=0.35 repeated measure test).

CONCLUSION

Blood glucose increased during maintenance of anesthesia with isoflurane compared to propofol during the surgery.

Cognitive function and oxidative stress after carotid endarterectomy: comparison of propofol to sevoflurane anesthesia

OBJECTIVE

To examine the antioxidant role of propofol in ischemia-reperfusion during carotid endarterectomy (CEA) and its influence on cognitive dysfunction after CEA.

DESIGN

A randomized prospective study.

SETTING

Single-center study in a university hospital.

PARTICIPANTS

Forty-four patients.

INTERVENTIONS

Patients underwent elective CEA under general anesthesia with either sevoflurane (group S, n = 21) or propofol (group P, n = 23).

MEASUREMENTS AND MAIN RESULTS

Cognitive function was assessed with the Mini-Mental State Examination (MMSE) before CEA, 1 hour after CEA, and 24 hours after CEA. Blood samples from the radial artery and the internal jugular vein were drawn before carotid clamping and 5 minutes following unclamping, and peripheral blood was obtained 24 hours postoperatively. Samples were analyzed for lactate, S100B, and P-selectin concentrations and for the antioxidative markers malondialdehyde/low-density lipoprotein ratio and nitrate + nitrite concentrations. Compared with group S, patients in group P exhibited a greater increase in their MMSE values 24 hours postoperatively. Patients who had their MMSE performance reduced at 24 hours also were significantly fewer in group P (13% v 43% in group S, p<0.05). Significantly lower levels of lactate and S100B were observed in arterial and jugular vein samples in group P. In addition, the jugular vein-arterial differences of malondialdehyde-to-low-density lipoprotein ratio and nitrates + nitrites concentrations were lower during propofol anesthesia.

CONCLUSIONS

Propofol seemed to improve cognitive performance after CEA. This improvement was associated with decreased indices of ischemic cerebral damage and seemed to be due to antioxidative effect in the ischemic cerebral circulation.

Neuroprotective effects of propofol in acute cerebral injury

Propofol (2,6-diisopropylphenol) is one of the most popular agents used for induction of anesthesia and long-term sedation, owing to its favorable pharmacokinetic profile, which ensures a rapid recovery even after prolonged administration. A neuroprotective effect, beyond that related to the decrease in cerebral metabolic rate for oxygen, has been shown to be present in many in vitro and in vivo established experimental models of mild/moderate acute cerebral ischemia. Experimental studies on traumatic brain injury are limited and less encouraging. Despite the experimental results and the positive effects on cerebral physiology (propofol reduces cerebral blood flow but maintains coupling with cerebral metabolic rate for oxygen and decreases intracranial pressure, allowing optimal intraoperative conditions during neurosurgical operations), no clinical study has yet indicated that propofol may be superior to other anesthetics in improving the neurological outcome following acute cerebral injury. Therefore, propofol cannot be indicated as an established clinical neuroprotectant per se, but it might play an important role in the so-called multimodal neuroprotection, a global strategy for the treatment of acute injury of the brain that includes preservation of cerebral perfusion, temperature control, prevention of infections, and tight glycemic control.

The intravenous anesthetic propofol inhibits hypoxia-inducible factor 1 activity in an oxygen tension-dependent manner

Hypoxia elicits a wide range of responses that occur at different organizational levels in the body. Hypoxia is not only a signal for energy conservation and metabolic change, but triggers expression of a select set of genes. The transcription factor hypoxia-inducible factor 1 (HIF-1) is now appreciated to be a master factor of the gene induction. Although knowledge on molecular mechanisms of HIF-1 activation in response to hypoxia is accumulating, the molecular mechanism of maintenance of HIF-1 activity under normoxic conditions remains to be elucidated. We demonstrate that the intravenous anesthetic propofol reversibly inhibits HIF-1 activity and the gene expression mediated by HIF-1 by blocking the synthesis of the HIF-1alpha subunit under 20% or 5% O2 conditions, but not under 1% O2 conditions.

Le propofol et l'AIVOC en neuro-anesthésie

Propofol is an intravenous anaesthetic agent, which presents interesting features for its use in neuro-anaesthesia: it is a powerful hypnotic that does not increase the intracranial pressure. The delay of recovery is short even after several hours of continuous infusion. This is essential for a fast neurologic examination. Continuous infusion should be preferred to bolus in order to prevent hypotension and decrease of the cerebral perfusion pressure. Target-controlled infusion models based on effect site concentrations are now available through several softwares. This technique appears especially useful for awake craniotomy and functional neurosurgery. The level of consciousness is easily fixed between deep anaesthesia and light sedation permitting to ask the patient to move following orders. A sedation controlled by the patient himself is even possible.

Evaluation of two-dimensional L-COSY and JPRESS using a 3 T MRI scanner: from phantoms to human brain in vivo

Localized versions of two-dimensional (2D) magnetic resonance spectroscopic (MRS) sequences, namely JPRESS and L-COSY, have been implemented on a whole-body 3T MRI/MRS scanner. Volume selection was achieved using three slice-selective radio-frequency (RF) pulses: 90 degrees-180 degrees-180 degrees in JPRESS and 90 degrees-180 degrees-90 degrees in L-COSY with a CHESS sequence prior to voxel localization for global water suppression. The last 180 degrees RF pulse was used for resolving the J-coupled cross peaks in JPRESS, whereas the last 90 degrees RF pulse was used for coherence transfer between J-coupled metabolites in L-COSY. A head MRI coil for 'transmission' and a 4 inch receive surface coil for 'reception' or a head coil transmit/receive were used. A total of 16 healthy volunteers were investigated using these 2D MRS sequences. Voxel sizes of 18 and 27 ml were localized in the occipito-parietal gray and white matter regions and the total duration for each 2D signal acquisition was typically 35 min. Compared with 2D L-COSY, reduced spectral width along the second spectral dimension and shorter 2D spectral acquisition were the major advantages of 2D JPRESS. In contrast, increased spectral width along the new spectral dimension in L-COSY resulted in an improved spectral dispersion enabling the detection of several brain metabolites at low concentrations that have not been resolved using the conventional one-dimensional (1D) MRS techniques. Due to increased sampling rate, severe loss of metabolite signals due to T2 during t1 was a major drawback of 2D JPRESS in vivo.

1,3-Dinitrobenzene inhibits mitochondrial complex II in rat and mouse brainstem and cortical astrocytes

1,3-Dinitrobenzene (DNB) produces edematous, glio-vascular lesions that are initially confined to brainstem nuclei with high energy requirements in rats and mice. Perturbation of energy producing processes in the cell is known to induce formation of the mitochondrial permeability transition pore (mtPTP) complex. Selective vulnerability of brainstem astrocytes to DNB is mediated by a 10-fold lower threshold for opening of the cyclosporin A-inhibitable mitochondrial permeability transition (MPT) pore than their cortical counterparts. Other nitrocompounds, such as 3-nitropropionic acid, selectively interfere with regional energy metabolism, including mitochondrial succinate dehydrogenase activity. However, the link between DNB-induced onset of the MPT and disruption of energy producing processes in the astrocyte remains unclear. The effects of DNB on succinate dehydrogenase activity were evaluated in cultured neonatal rat and mouse brainstem and cortical astrocytes. Both histochemical and spectrophotometric assays confirmed significant temporal inhibition of SDH activity in brainstem and cortical astrocytes 0.5, 2 and 5h following exposure to 100 microM DNB in vitro. Although DNB-induced inhibition of SDH was significantly decreased by CsA pretreatment in brainstem astrocytes after 0.5 and 2h and with a second pore inhibitor, bongkrekic acid (BKA) after 5h, both inhibitors failed to reduce inhibition of SDH activity in cortical astrocytes. These data suggest that DNB-induced inhibition of SDH may be independent of differential regional activation of the mtPTP complex in astrocytes and that an unidentified cyclosporin A-inhibitable factor mediates DNB-induced loss of SDH function.

Anti-epileptic drugs as possible neuroprotectants in cerebral ischemia

Many similarities exist between cerebral ischemia and epilepsy regarding brain-damaging and auto-protective mechanisms that are activated following the injurious insult. Therefore, drugs that are effective in minimizing seizure-induced brain damage may also be useful in minimizing ischemic injury. Use of such drugs in stroke victims may have important clinical and financial advantages. Therefore, the authors conducted a Medline search of studies involving the use of anti-epileptic drugs (AEDs) as possible neuroprotectants and summarize the data. Most AEDs have been tested in animal models of focal or global ischemia and some were already tested in humans, for a possible neuroprotective effect. The existing data is rather scant and insufficient but it appears that only drugs that have multiple mechanisms of action seem to have some potential in conferring a degree of neuroprotection that could be clinically applicable to stroke patients. In conclusion, some of the newer AEDs show promise as possible neuroprotectants in the setup of acute ischemic stroke but more studies are needed before clinical trials in humans could be undertaken.