Sevoflurane but not propofol increases interstitial glycolysis metabolites availability during tourniquet-induced ischaemia-reperfusion

Influence of anesthesia type on post-reperfusion syndrome during liver transplantation: a single-center retrospective study

Background

Post-reperfusion syndrome (PRS) results in sudden hemodynamic instability following graft reperfusion. Although PRS is known to influence outcomes following liver transplantation, little is known regarding the effects of anesthetics on PRS. This study investigated the association between the type of anesthetic agent and PRS in liver transplantation.

Methods

This single-center retrospective cohort study included patients who underwent liver transplantation between June 2016 and December 2019. Patients were divided into sevoflurane and propofol groups according to the anesthetic agent used. Stabilized inverse probability of treatment weighting (IPTW) analysis was performed to investigate the association between PRS identified based on blood pressure recordings and the type of anesthesia. Associations between the anesthetic agent and the duration of hypotension as well as early postoperative outcomes were also investigated.

Results

Data were analyzed for 398 patients, 304 (76.4%) and 94 (23.6%) of whom were anesthetized with propofol and sevoflurane, respectively. PRS developed in 40.7% of the 398 patients. Following stabilized IPTW analysis, the association with PRS was lower in the sevoflurane group than in the propofol group (odds ratio, 0.47; P = 0.018). However, there was no association between the type of anesthetic used and early postoperative outcomes.

Conclusions

The association of PRS was lower in the sevoflurane group than in the propofol group. However, there was no association between the type of anesthetic and the early postoperative outcomes. Further studies are required to determine the optimal anesthetic for liver transplantation.

A preliminary study to assess neutrophil and endothelial response to knee arthroplasty with the use of a tourniquet : effects of spinal or sevoflurane anesthesia

Background : During orthopedic surgery, the use of a pneumatic tourniquet results in side effects secondary to ischemia-reperfusion phenomena. We tested the hypothesis that total knee arthroplasty with a tourniquet is associated with increase in plasma concentrations of biomarkers of neutrophil activation and endothelial injury. The second aim was to compare these changes during spinal or general inhalational anesthesia. Methods : 40 adult ASA I-II patients scheduled for total knee arthroplasty with a tourniquet under spinal or sevoflurane anesthesia were included. Venous blood samples were collected before surgery, 1 h, 3 h, and 24 h after tourniquet deflation. To assess neutrophil activation, plasma concentrations of total and active fractions of myeloperoxidase, as well as elastase concentrations and proteolytic activity were measured. Endothelial injury was assessed by measurement of plasma concentrations of syndecan-1, soluble thrombomodulin, soluble E-selectin, and vascular endothelial growth factor. Results were analyzed with a two-way analysis of variance. P< 0.05 was considered statistically significant. Results : Plasma concentrations of active but not total myeloperoxidase and elastase significantly increased following tourniquet deflation. The level of syndecan-1, soluble thrombomodulin, soluble E-selectin, but not vascular endothelial growth factor, significantly decreased postoperatively. These changes of biomarkers were similar during spinal and sevoflurane anesthesia. Conclusions : Total knee arthroplasty with pneumatic tourniquet is associated with systemic release of markers of neutrophil activation which was comparable during spinal or sevoflurane anesthesia. Systemic expression of endothelial injury was not detected in our clinical conditions.

Intravenous versus inhalational maintenance of anaesthesia for postoperative cognitive outcomes in elderly people undergoing non-cardiac surgery

BACKGROUND

The use of anaesthetics in the elderly surgical population (more than 60 years of age) is increasing. Postoperative delirium, an acute condition characterized by reduced awareness of the environment and a disturbance in attention, typically occurs between 24 and 72 hours after surgery and can affect up to 60% of elderly surgical patients. Postoperative cognitive dysfunction (POCD) is a new-onset of cognitive impairment which may persist for weeks or months after surgery.Traditionally, surgical anaesthesia has been maintained with inhalational agents. End-tidal concentrations require adjustment to balance the risks of accidental awareness and excessive dosing in elderly people. As an alternative, propofol-based total intravenous anaesthesia (TIVA) offers a more rapid recovery and reduces postoperative nausea and vomiting. Using TIVA with a target controlled infusion (TCI) allows plasma and effect-site concentrations to be calculated using an algorithm based on age, gender, weight and height of the patient.TIVA is a viable alternative to inhalational maintenance agents for surgical anaesthesia in elderly people. However, in terms of postoperative cognitive outcomes, the optimal technique is unknown.

OBJECTIVES

To compare maintenance of general anaesthesia for elderly people undergoing non-cardiac surgery using propofol-based TIVA or inhalational anaesthesia on postoperative cognitive function, mortality, risk of hypotension, length of stay in the postanaesthesia care unit (PACU), and hospital stay.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 11), MEDLINE (1946 to November 2017), Embase (1974 to November 2017), PsycINFO (1887 to November 2017). We searched clinical trials registers for ongoing studies, and conducted backward and forward citation searching of relevant articles.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) with participants over 60 years of age scheduled for non-cardiac surgery under general anaesthesia. We planned to also include quasi-randomized trials. We compared maintenance of anaesthesia with propofol-based TIVA versus inhalational maintenance of anaesthesia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data, assessed risk of bias, and synthesized findings.

MAIN RESULTS

We included 28 RCTs with 4507 randomized participants undergoing different types of surgery (predominantly cardiovascular, laparoscopic, abdominal, orthopaedic and ophthalmic procedures). We found no quasi-randomized trials. Four studies are awaiting classification because we had insufficient information to assess eligibility.All studies compared maintenance with propofol-based TIVA versus inhalational maintenance of anaesthesia. Six studies were multi-arm and included additional TIVA groups, additional inhalational maintenance or both. Inhalational maintenance agents included sevoflurane (19 studies), isoflurane (eight studies), and desflurane (three studies), and was not specified in one study (reported as an abstract). Some studies also reported use of epidural analgesia/anaesthesia, fentanyl and remifentanil.We found insufficient reporting of randomization methods in many studies and all studies were at high risk of performance bias because it was not feasible to blind anaesthetists to study groups. Thirteen studies described blinding of outcome assessors. Three studies had a high of risk of attrition bias, and we noted differences in the use of analgesics between groups in six studies, and differences in baseline characteristics in five studies. Few studies reported clinical trials registration, which prevented assessment of risk of selective reporting bias.We found no evidence of a difference in incidences of postoperative delirium according to type of anaesthetic maintenance agents (odds ratio (OR) 0.59, 95% confidence interval (CI) 0.15 to 2.26; 321 participants; five studies; very low-certainty evidence); we noted during sensitivity analysis that using different time points in one study may influence direction of this result. Thirteen studies (3215 participants) reported POCD, and of these, six studies reported data that could not be pooled; we noted no difference in scores of POCD in four of these and in one study, data were at a time point incomparable to other studies. We excluded one large study from meta-analysis because study investigators had used non-standard anaesthetic management and this study was not methodologically comparable to other studies. We combined data for seven studies and found low-certainty evidence that TIVA may reduce POCD (OR 0.52, 95% CI 0.31 to 0.87; 869 participants).We found no evidence of a difference in mortality at 30 days (OR 1.21, 95% CI 0.33 to 4.45; 271 participants; three studies; very low-certainty evidence). Twelve studies reported intraoperative hypotension. We did not perform meta-analysis for 11 studies for this outcome. We noted visual inconsistencies in these data, which may be explained by possible variation in clinical management and medication used to manage hypotension in each study (downgraded to low-certainty evidence); one study reported data in a format that could not be combined and we noted little or no difference between groups in intraoperative hypotension for this study. Eight studies reported length of stay in the PACU, and we did not perform meta-analysis for seven studies. We noted visual inconsistencies in these data, which may be explained by possible differences in definition of time points for this outcome (downgraded to very low-certainty evidence); data were unclearly reported in one study. We found no evidence of a difference in length of hospital stay according to type of anaesthetic maintenance agent (mean difference (MD) 0 days, 95% CI -1.32 to 1.32; 175 participants; four studies; very low-certainty evidence).We used the GRADE approach to downgrade the certainty of the evidence for each outcome. Reasons for downgrading included: study limitations, because some included studies insufficiently reported randomization methods, had high attrition bias, or high risk of selective reporting bias; imprecision, because we found few studies; inconsistency, because we noted heterogeneity across studies.

AUTHORS' CONCLUSIONS

We are uncertain whether maintenance with propofol-based TIVA or with inhalational agents affect incidences of postoperative delirium, mortality, or length of hospital stay because certainty of the evidence was very low. We found low-certainty evidence that maintenance with propofol-based TIVA may reduce POCD. We were unable to perform meta-analysis for intraoperative hypotension or length of stay in the PACU because of heterogeneity between studies. We identified 11 ongoing studies from clinical trials register searches; inclusion of these studies in future review updates may provide more certainty for the review outcomes.

Stress-induced hyperglycaemia and venous thromboembolism following total hip or total knee arthroplasty

Stress-induced hyperglycaemia is common during orthopaedic surgery. In addition, hyperglycaemia activates coagulation. The aim of the study was to assess whether stress-induced hyperglycaemia is associated with symptomatic or asymptomatic venous thromboembolism (VTE) following orthopaedic surgery. We performed post-hoc analyses in the four RECORD studies (REgulation of Coagulation in major Orthopaedic surgery reducing the Risk of Deep venous thrombosis and pulmonary embolism). Separate analyses were performed for patients undergoing elective total hip or knee replacement. Outcome measures were symptomatic VTE and “total VTE” (defined as the composite of symptomatic VTE, asymptomatic DVT assessed by per protocol venography and all cause mortality). Glucose levels were measured pre-op and 6 hours post-op, categorised into quartiles, based on the distribution in the respective cohorts. The influence of glucose, adjusted for body mass index, age, gender and diabetes mellitus on VTE was assessed by logistic regression analyses. A total of 12,383 patients were eligible for assessment of symptomatic VTE, and 8,512 patients were eligible for assessment of total VTE. Increased glucose levels after total hip replacement were associated with total VTE; adjusted odds ratio (OR) highest versus lowest quartile 1.9 (95% confidence interval [CI] 1.3 to 3.0). Furthermore, increase in glucose levels during total hip replacement was associated with total VTE (OR highest versus lowest quartile 1.8 (95%CI 1.2 to 2.8). This was not observed in patients undergoing total knee replacement, probably due to differences in the applied surgical procedures.

Effects of inhalation of low-dose nitrite or carbon monoxide on post-reperfusion mitochondrial function and tissue injury in hemorrhagic shock swine

Introduction

Tissue reperfusion following hemorrhagic shock may paradoxically cause tissue injury and organ dysfunction by mitochondrial free radical expression. Both nitrite and carbon monoxide (CO) may protect from this reperfusion injury by limiting mitochondrial free radial production. We explored the effects of very small doses of inhaled nitrite and CO on tissue injury in a porcine model of hemorrhagic shock.

Methods

Twenty pigs (mean wt. 30.6 kg, range 27.2 to 36.4 kg) had microdialysis catheters inserted in muscle, peritoneum, and liver to measure lactate, pyruvate, glucose, glycerol, and nitrite. Nineteen of the pigs were bled at a rate of 20 ml/min to a mean arterial pressure of 30 mmHg and kept between 30 and 40 mmHg for 90 minutes and then resuscitated. One pig was instrumented but not bled (sham). Hemorrhaged animals were randomized to inhale nothing (control, n = 7), 11 mg nitrite (nitrite, n = 7) or 250 ppm CO (CO, n = 5) over 30 minutes before fluid resuscitation. Mitochondrial respiratory control ratio was measured in muscle biopsies. Repeated measures from microdialysis catheters were analyzed in a random effects mixed model.

Results

Neither nitrite nor CO had any effects on the measured hemodynamic variables. Following inhalation of nitrite, plasma, but not tissue, nitrite increased. Following reperfusion, plasma nitrite only increased in the control and CO groups. Thereafter, nitrite decreased only in the nitrite group. Inhalation of nitrite was associated with decreases in blood lactate, whereas both nitrite and CO were associated with decreases in glycerol release into peritoneal fluid. Following resuscitation, the muscular mitochondrial respiratory control ratio was reduced in the control group but preserved in the nitrite and CO groups.

Conclusions

We conclude that small doses of nebulized sodium nitrite or inhaled CO may be associated with intestinal protection during resuscitation from severe hemorrhagic shock.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0903-z) contains supplementary material, which is available to authorized users.

The comparison of the effects of sevoflurane inhalation anesthesia and intravenous propofol anesthesia on oxidative stress in one lung ventilation

BACKGROUND

The aim of this study is to compare the effects of sevoflurane and propofol on one lung ventilation (OLV) induced ischemia-reperfusion injury (IRI) by determining the blood gas, ischemia-modified albumin (IMA), and malonyldialdehyde (MDA).

MATERIAL AND METHODS

Forty-four patients undergoing thoracic surgery with OLV were randomized in two groups (sevoflurane Group S, propofol Group P). Anesthesia was inducted with thiopental and was maintained with 1-2.5% of sevoflurane within the 40/60% of O2/N2O mixture in Group S. In Group P anesthesia was inducted with propofol and was maintained with infusion of propofol and remifentanil. Hemodynamic records and blood samples were obtained before anesthesia induction (t 1), 1 min before two lung ventilation (t 2), 30 min after two lung ventilation (t 3), and postoperative sixth hours (t 4).

RESULTS

Heart rate at t 2 and t 3 in Group P was significantly lower than that in Group S. While there were no significant differences in terms of pH and pCO2, pO2 at t 2 and t 3 in Group S was significantly lower than that in Group P. IMA levels at t 4 in Group S were significantly lower than those in Group P.

CONCLUSION

Sevoflurane may offer protection against IRI after OLV in thoracic surgery.

Ischemia-reperfusion injury and volatile anesthetics

Ischemia-reperfusion injury (IRI) is induced as a result of reentry of the blood and oxygen to ischemic tissue. Antioxidant and some other drugs have protective effect on IRI. In many surgeries and clinical conditions IRI is counteract inevitable. Some anesthetic agents may have a protective role in this procedure. It is known that inhalational anesthetics possess protective effects against IRI. In this review the mechanism of preventive effects of volatile anesthetics and different ischemia-reperfusion models are discussed.

The effects of spinal, inhalation, and total intravenous anesthetic techniques on ischemia-reperfusion injury in arthroscopic knee surgery

PURPOSE

To compare the effects of different anesthesia techniques on tourniquet-related ischemia-reperfusion by measuring the levels of malondialdehyde (MDA), ischemia-modified albumin (IMA) and neuromuscular side effects.

METHODS

Sixty ASAI-II patients undergoing arthroscopic knee surgery were randomised to three groups. In Group S, intrathecal anesthesia was administered using levobupivacaine. Anesthesia was induced and maintained with sevoflurane in Group I and TIVA with propofol in Group T. Blood samples were obtained before the induction of anesthesia (t1), 30 min after tourniquet inflation (t2), immediately before (t3), and 5 min (t4), 15 min (t5), 30 min (t 6), 1 h (t7), 2 h (t8), and 6 h (t9) after tourniquet release.

RESULTS

MDA and IMA levels increased significantly compared with baseline values in Group S at t2-t 9 and t2-t7. MDA levels in Group T and Group I were significantly lower than those in Group S at t2-t8 and t2-t9. IMA levels in Group T were significantly lower than those in Group S at t2-t7. Postoperatively, a temporary 1/5 loss of strength in dorsiflexion of the ankle was observed in 3 patients in Group S and 1 in Group I.

CONCLUSIONS

TIVA with propofol can make a positive contribution in tourniquet-related ischemia-reperfusion.

Tourniquet-induced ischemia-reperfusion injuries during extremity surgery at children's age: impact of anesthetic chemical structure

OBJECTIVES

The aim of this study was to determine the relationship between the antioxidant profile of anesthetics and its relation to total antioxidant capacity (TAC) of plasma in children who underwent tourniquet-induced ischemia-reperfusion (IR) injury during extremity operations.

METHODS

Children were randomized into three groups: general inhalational anesthesia with sevoflurane (group S), total intravenous anesthesia (TIVA) with propofol (group T), and regional anesthesia (group R). Venous blood samples were obtained before peripheral nerve block and induction of general anesthesia (baseline), 1 minute before tourniquet release (BTR), and 5 and 20 minutes after tourniquet release (ATR). Plasma TAC as well as antioxidant potential of propofol, thiopental, and bupivacaine were measured using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay.

RESULTS

Plasma TAC in group T was increased significantly at 20 minutes ATR in comparison with basal and BTR values, and also was significantly higher in comparison with plasma TAC in groups S and R measured at the same time point. The radical scavenging activity of anesthetics in vitro indicated that only propofol possessed a significant antioxidative activity in the reaction with DPPH radical in comparison with thiopental and bupivacaine.

DISCUSSION

These data confirm that TIVA with propofol attenuates oxidative stress related to tourniquet-induced ischaemia-reperfusion injury in children.

Microarray analyses of genes regulated by isoflurane anesthesia in vivo: a novel approach to identifying potential preconditioning mechanisms

BACKGROUND

Although general anesthetics are recognized for their potential to render patients unconscious during surgery, exposure can also lead to long-term outcomes of both cellular damage and protection. As regards the latter, delayed anesthetic preconditioning is an evolutionarily conserved physiological response that has the potential for protecting against ischemic injury in a number of tissues. Although it is known that delayed preconditioning requires de novo protein synthesis, knowledge of anesthetic-regulated genes is incomplete. In this study, we used the conserved nature of preconditioning to analyze differentially regulated genes in 3 different rat tissues. We hypothesized that by selecting those genes regulated in multiple tissues, we could develop a focused list of gene candidates potentially involved in delayed anesthetic preconditioning.

METHODS

Young adult male Sprague-Dawley rats were anesthetized with a 2% isoflurane/98% air mixture for 90 minutes. Immediately after anesthetic exposure, animals were euthanized and liver, kidney, and heart were removed and total RNA was isolated. Differential gene expression was determined using rat oligonucleotide gene arrays. Array data were analyzed to select for genes that were significantly regulated in multiple tissues.

RESULTS

All 3 tissues showed differentially regulated genes in response to a clinically relevant exposure to isoflurane. Analysis of coordinately regulated genes yielded a focused list of 34 potential gene candidates with a range of ontologies including regulation of inflammation, modulation of apoptosis, regulation of ion gradients, and maintenance of energy pathways.

CONCLUSIONS

Through using an analysis approach focusing on coordinately regulated genes, we were able to generate a focused list of interesting gene candidates with potential to enable future preconditioning studies.

Potential non-hypoxic/ischemic causes of increased cerebral interstitial fluid lactate/pyruvate ratio: a review of available literature

Microdialysis, an in vivo technique that permits collection and analysis of small molecular weight substances from the interstitial space, was developed more than 30 years ago and introduced into the clinical neurosciences in the 1990s. Today cerebral microdialysis is an established, commercially available clinical tool that is focused primarily on markers of cerebral energy metabolism (glucose, lactate, and pyruvate) and cell damage (glycerol), and neurotransmitters (glutamate). Although the brain comprises only 2% of body weight, it consumes 20% of total body energy. Consequently, the ability to monitor cerebral metabolism can provide significant insights during clinical care. Measurements of lactate, pyruvate, and glucose give information about the comparative contributions of aerobic and anaerobic metabolisms to brain energy. The lactate/pyruvate ratio reflects cytoplasmic redox state and thus provides information about tissue oxygenation. An elevated lactate pyruvate ratio (>40) frequently is interpreted as a sign of cerebral hypoxia or ischemia. However, several other factors may contribute to an elevated LPR. This article reviews potential non-hypoxic/ischemic causes of an increased LPR.

Biomarkers of Oxidative Stress and Endothelial Dysfunction After Tourniquet Release in Children

Pneumatic tourniquets are widely used in pediatric extremity surgery to provide a bloodless field and facilitate dissection. This prospective study was carried out to examine possible effect of different anesthesia techniques on oxidative stress and endothelial dysfunction connected with ischemia-reperfusion injury during extremity operations at children's age. Patients were randomized into three groups of 15 patients each: general inhalational anesthesia with sevoflurane (group S), total intravenous anesthesia with propofol (group T) and regional anesthesia (group R). Venous blood samples for determination of the malondialdehyde in plasma and erythrocytes, protein carbonyl groups concentration as well as plasma nitrites and nitrates level and xanthine oxidase activity were obtained at four time points: before peripheral nerve block and induction of general anesthesia (baseline), 1 min before tourniquet release, 5 and 20 min after tourniquet release. This study demonstrates that total intravenous anesthesia with propofol and regional anesthesia techniques provide better antioxidant defense and reduce endothelial dysfunction than general inhalational anesthesia with sevoflurane during tourniquet application in pediatric extremity surgery.

Bioenergetic homeostasis decides neuroprotection or neurotoxicity induced by volatile anesthetics: a uniform mechanism of dual effects

The commonly used volatile anesthetic isoflurane or sevoflurane has been shown to be both neuroprotective and neurotoxic in various cell cultures and animal models. Some possible mechanisms have been raised to elucidate volatile anesthetics-induced neuroprotection or neurotoxicity, respectively. However, none of these can reconcile the linkage between their dual effects. Similar to volatile anesthetics, some drugs and nonpharmacological factors also can produce neuroprotection and neurotoxicity, which is associated with bioenergetic metabolism of neuronal cells. Here we present a uniform mechanism, bioenergetic homeostasis hypothesis, to explain neuroprotection and neurotoxicity induced by volatile anesthetics. The numerous evidences have shown that volatile anesthetics could affect mitochondrial electron transport complexes and glycolysis related pathways in cells, which could alter intracellular calcium homeostasis, ROS production and adenosine triphosphate (ATP) synthesis. Duration and concentration of exposure to volatile anesthetics could play a role on severity of bioenergy inhibition. Mild bioenergetic metabolism inhibition trigger signaling events involving preconditioning on neurons, and further bioenergy impairment could lead to neuronal cellular apoptosis, inhibition of neurogenesis and elevated β-Secretase, which drive pathogenesis of neurodegeneration.

Enhanced glucose uptake via GLUT4 fuels recovery from calcium overload after ischaemia-reperfusion injury in sevoflurane- but not propofol-treated hearts

BACKGROUND

So far, no study has explored the effects of sevoflurane, propofol, and Intralipid on metabolic flux rates of fatty acid oxidation (FOX) and glucose oxidation (GOX) in hearts exposed to ischaemia-reperfusion.

METHODS

Isolated paced working rat hearts were exposed to 20 min of ischaemia and 30 min of reperfusion. Peri-ischaemic sevoflurane (2 vol%) and propofol (100 µM) in the formulation of 1% Diprivan(®) were assessed for their effects on oxidative energy metabolism and intracellular diastolic and systolic Ca(2+) concentrations. Substrate flux was measured using [(3)H]palmitate and [(14)C]glucose and [Ca(2+)] using indo-1AM. Western blotting was used to determine the expression of the sarcolemmal glucose transporter GLUT4 in lipid rafts. Biochemical analyses of nucleotides, ceramides, and 32 acylcarnitines were also performed.

RESULTS

Sevoflurane, but not propofol, improved the recovery of left ventricular work (P=0.008) and myocardial efficiency (P=0.008) compared with untreated ischaemic hearts. This functional improvement was accompanied by reduced increases in post-ischaemic diastolic and systolic intracellular Ca(2+) concentrations (P=0.008). Sevoflurane, but not propofol, increased GOX (P=0.009) and decreased FOX (P=0.019) in hearts exposed to ischaemia-reperfusion. GLUT4 expression was markedly increased in lipid rafts of sevoflurane-treated hearts (P=0.016). Increased GOX closely correlated with reduced Ca(2+) overload. Intralipid alone decreased energy charge and increased long-chain and hydroxyacylcarnitine tissue levels, whereas sevoflurane decreased toxic ceramide formation.

CONCLUSIONS

Enhanced glucose uptake via GLUT4 fuels recovery from Ca(2+) overload after ischaemia-reperfusion in sevoflurane- but not propofol-treated hearts. The use of a high propofol concentration (100 µM) did not result in similar protection.

Detection of Cerebral Compromise With Multimodality Monitoring in Patients With Subarachnoid Hemorrhage

BACKGROUND:

Studies in traumatic brain injury suggest that monitoring techniques such as brain tissue oxygen (Pbto2) and cerebral microdialysis may complement conventional intracranial pressure (ICP) and cerebral perfusion pressure (CPP) measurements.

OBJECTIVE:

In this study of poor-grade (Hunt and Hess grade IV and V) subarachnoid hemorrhage (SAH) patients, we examined the prevalence of brain hypoxia and brain energy dysfunction in the presence of normal and abnormal ICP and CPP.

METHODS:

SAH patients who underwent multimodal neuromonitoring and cerebral microdialysis were studied. We examined the frequency of brain hypoxia and energy dysfunction in different ICP and CPP ranges and the relationship between Pbto2 and the lactate/pyruvate ratio (LPR).

RESULTS:

A total of 2394 samples from 19 patients were analyzed. There were 149 samples with severe brain hypoxia (Pbto2 ≤10 mm Hg) and 347 samples with brain energy dysfunction (LPR &gt;40). The sensitivities of abnormal ICP or CPP for elevated LPR and reduced Pbto2 were poor (21.2% at best), and the LPR or Pbto2 was abnormal in many instances when ICP or CPP was normal. Severe brain hypoxia was often associated with an LPR greater than 40 (86% of samples). In contrast, mild brain hypoxia (≤20 mm Hg) and severe brain hypoxia were observed in only 53% and 36% of samples with brain energy dysfunction, respectively.

CONCLUSION:

Our data demonstrate that ICP and CPP monitoring may not always detect episodes of cerebral compromise in SAH patients. Our data suggest that several complementary monitors may be needed to optimize the care of poor-grade SAH patients.

Thiopental improves renal ischemia-reperfusion injury

Ischemia/reperfusion (I/R) occurs in a number of pathological conditions, including myocardial infarction, stroke, aortic surgery, cardiopulmonary bypass surgery, organ transplantation, resuscitation, and critical care. Massive and abrupt release of oxygen-free radicals after reperfusion triggers oxidative damage. Before critical operations or after resuscitation, it would be wise to find a suitable prophylactic treatment to avoid I/R damage. We aimed to determine whether several commonly used intravenous anesthetics protect against renal I/R injury.

METHODS

Animals were randomly divided into seven groups, each consisting of six animals: sham group, control group, thiopental group, propofol group, intralipid group, etomidate group, and ketamine group. At the end of the 60-min ischemic period, 60 min reperfusion was established and the materials administered 15 min before the reperfusion. At the end of the reperfusion period, the samples of blood and tissue were reaped for biochemical and serological evaluation.

RESULTS

I/R procedure significantly increased malondialdehyde (MDA) levels, decreased catalase (CAT) activities, and superoxide dismutase (SOD) levels. The lowest MDA mean level was in the thiopental group and the highest MDA mean level was in control group. The lowest CAT mean level was in the intralipid group and the highest CAT mean level was in the etomidate group. The lowest SOD mean level was in the control group and the highest SOD mean level was in the propofol group.

CONCLUSION

Thiopental and propofol, especially thiopental, are more effective to protect renal I/R injury.

The effects of different anesthesia techniques on free radical production after tourniquet-induced ischemia-reperfusion injury at children's age

Background/Aim. Reperfusion of previously ischemic tissue leads to injuries mediated by reactive oxygen species. The aim of the study was to investigate the effects of different anesthesia techniques on oxidative stress caused by tourniquetinduced ischemia-reperfusion (IR) injury during extremity operations at children's age. Methods. The study included 45 patients American Society of Anesthesiologists (ASA) classification I or II, 8 to 17 years of age, undergoing orthopedic procedures that required bloodless limb surgery. The children were randomized into three groups of 15 patients each: general inhalational anesthesia with sevoflurane (group S), total intravenous anesthesia with propofol (group T) and regional anesthesia (group R). Venous blood samples were obtained at four time points: before peripheral nerve block and induction of general anesthesia (baseline), 1 min before tourniquet release (BTR), 5 and 20 min after tourniquet release (ATR). Postischemic reperfusion injury was estimated by measurement of concentration of malondialdehyde (MDA) in plasma and erythrocytes as well as catalase (CAT) activity. Results. Plasma MDA concentration in the group S was significantly higher at 20 min ATR in comparison with the groups T and R (6.78 ? 0.33 ?molL-1-1 vs 4.07 ? 1.53 and 3.22 ? 0.9. ?molL-1-1, respectively). There was a significant difference in MDA concentration in erytrocythes between the groups S and T after 5 min of reperfusion (5.88 ? 0.88 vs 4.27 ? 1.04 nmol/mlEr, p < 0.05). Although not statistically significant, CAT activity was slightly increased as compared to baseline in both groups S and R. In the group T, CAT activity decreased at all time points when compared with baseline, but the observed decrease was only statistically significant at BTR (34.70 ? 9.27 vs 39.69 ? 12.91 UL-1, p < 0.05). Conclusion. Continuous propofol infusion and regional anesthesia techniques attenuate lipid peroxidation and IR injury connected with tourniquet application in pediatric extremity surgery.