Sevoflurane inside and outside the operating room

Anesthesia choice and its potential impact on endoluminal functional lumen imaging probe measurements in esophageal motility disorders

BACKGROUND AND AIMS

The widespread use of peroral endoscopic myotomy (POEM) has revolutionized the management of esophageal motility disorders (EMDs). The introduction of an endoluminal functional lumen imaging probe (EndoFLIP, Medtronic, Dublin, Ireland) can serve as a complementary diagnostic tool to assess the mechanical properties (ie, pressure, diameter, distensibility, topography) of the esophagus. During EndoFLIP measurements, different anesthesia techniques may induce variable degrees of neuromuscular blockade, potentially affecting esophageal motility and altering the results of EndoFLIP metrics. The aim of this study was to compare the impact of using total intravenous anesthesia (TIVA) versus general anesthesia with inhalational anesthetics (GAIA) on diagnostic EndoFLIP measurements.

METHODS

This retrospective study included all adult patients (≥18 years) undergoing EndoFlip during the POEM procedure at our institution between February 2017 and February 2022. Differences in pressure, diameter, and distensibility index were obtained by using propofol-based TIVA versus sevoflurane-based GAIA with a 30 mL and a 60 mL balloon. The differences were divided into terciles and compared between diagnoses by using univariate comparisons and logistic regression models.

RESULTS

A total of 49 patients were included (39% type I achalasia, 43% type II or III achalasia, and 18% jackhammer esophagus [JE]). Compared with spastic disorders (types II and III achalasia and JE), type I had lower values of pressure differences at 60 mL in univariate (3.75 vs 15.20, P = .001) and multivariate (adjusted odds ratio, .89; 95% confidence interval, .82-.978) analyses. Compared with type I, types II and III achalasia had higher rates of pressure differences at 60 mL in the univariate (9.85 vs 3.75, P = .04) analysis and nearly reached significance in the multivariate analysis (1.09; 95% confidence interval, 1-1.20). Compared with type I achalasia, JE exhibited higher values in pressure differences at 60 mL (27.7 vs 3.75, P < .001).

CONCLUSIONS

Esophageal pressure, as measured by EndoFLIP, was significantly reduced when patients were sedated with sevoflurane-based GAIA. The use of sevoflurane-based GAIA for diagnostic EndoFLIP may potentially lead to the misclassification of spastic disorders as type I achalasia. Propofol-based TIVA should therefore be considered over sevoflurane-based GAIA for sedation during the diagnostic test.

Intraoperative Coronary Spasm: A Potential Case of Vasospastic Angina

Prinzmetal's angina typically features spasms of the coronary arteries due to the hyperreactivity of the vascular smooth muscle cells of the vessels to a nonspecific stimulus. Reports of coronary spasm during general anesthesia are rare, but in such cases, diagnosis is suggested by a framework of angina at rest and changes in the electrocardiogram (ECG) or coronary reactivity tests with ergonovine or acetylcholine. The present study describes a case of coronary spasm induced by general anesthesia associated with several cardiovascular risk factors and the usage of vasoactive drugs that was documented by angiography without using stimulating drugs and treated with intracoronary nitroglycerin. The patient was a 58-year-old male who was designated for carotid endarterectomy due to the stenosis (70%) of the right internal carotid artery by an atheromatous plaque after visiting the emergency department with a sensorimotor deficit in the left upper limb and bifrontal headaches with sudden onset. During the surgical intervention, after the administration of 10 mg of intravenous ephedrine, cardiorespiratory arrest occurred, with alternation between defibrillable and non-defibrillable heart paces. After the recovery of spontaneous circulation after 50 minutes of resuscitation maneuvers, the patient was transported to the hemodynamics laboratory, where there were recurrent episodes of ventricular fibrillation during the angioplasty of the anterior descending artery. After direct stent implantation, pre- and post-stent spasms were verified and reversed after the administration of intracardiac nitroglycerin. The spasm was a possible complication of anesthesia and responded to treatment with nitrates and calcium channel blockers. We would like to emphasize the importance of cardiac monitoring during surgery and anesthesia.

The Myc Family and the Metastasis Suppressor NDRG1: Targeting Key Molecular Interactions with Innovative Therapeutics

Cancer is a leading cause of death worldwide, resulting in ∼10 million deaths in 2020. Major oncogenic effectors are the Myc proto-oncogene family, which consists of three members including c-Myc, N-Myc, and L-Myc. As a pertinent example of the role of the Myc family in tumorigenesis, amplification of MYCN in childhood neuroblastoma strongly correlates with poor patient prognosis. Complexes between Myc oncoproteins and their partners such as hypoxia-inducible factor-1α and Myc-associated protein X (MAX) result in proliferation arrest and pro-proliferative effects, respectively. Interactions with other proteins are also important for N-Myc activity. For instance, the enhancer of zest homolog 2 (EZH2) binds directly to N-Myc to stabilize it by acting as a competitor against the ubiquitin ligase, SCFFBXW7, which prevents proteasomal degradation. Heat shock protein 90 may also be involved in N-Myc stabilization since it binds to EZH2 and prevents its degradation. N-Myc downstream-regulated gene 1 (NDRG1) is downregulated by N-Myc and participates in the regulation of cellular proliferation via associating with other proteins, such as glycogen synthase kinase-3β and low-density lipoprotein receptor-related protein 6. These molecular interactions provide a better understanding of the biologic roles of N-Myc and NDRG1, which can be potentially used as therapeutic targets. In addition to directly targeting these proteins, disrupting their key interactions may also be a promising strategy for anti-cancer drug development. This review examines the interactions between the Myc proteins and other molecules, with a special focus on the relationship between N-Myc and NDRG1 and possible therapeutic interventions. SIGNIFICANCE STATEMENT: Neuroblastoma is one of the most common childhood solid tumors, with a dismal five-year survival rate. This problem makes it imperative to discover new and more effective therapeutics. The molecular interactions between major oncogenic drivers of the Myc family and other key proteins; for example, the metastasis suppressor, NDRG1, may potentially be used as targets for anti-neuroblastoma drug development. In addition to directly targeting these proteins, disrupting their key molecular interactions may also be promising for drug discovery.

Effects of different plasma target concentrations of remifentanil on the MACBAR of sevoflurane in children with laparoscopic surgery

Background

To investigate the effects of different plasma target concentrations of remifentanil on the minimum alveolar concentration (MAC) for blocking adrenergic response (BAR) of sevoflurane in children with laparoscopic herniorrhaphy.

Methods

Seventy-five children with 3-7 years old scheduled for laparoscopic herniorrhaphy were randomly divided into group R₀, group R_1, and group R₂ according to different remifentanil plasma target concentration (0, 1, and 2 ngml^-1), respectively. The MAC_BAR of sevoflurane was determined by the up-and-down and sequential method in each group. The concentrations of epinephrine and noradrenaline were also determined at corresponding time points.

Results

A total of 52 child patients were used among the anticipated 75 patients. In groups R₀, R_1, and R₂, the MAC_BAR of sevoflurane was (3.29 ± 0.17) %, (2.12 ± 0.10) % and (1.29 ± 0.11) %, respectively, and a significant difference was found among the three groups (P<0.05). The changes of epinephrine and noradrenaline concentrations in each group before and after insufflation of carbon dioxide pneumoperitoneum showed no significant differences.

Conclusion

Remifentanil by target-controlled infusion can effectively reduce the MAC_BAR of sevoflurane during laparoscopic surgery in children. At a similar effect of MAC_BAR, both the changes of epinephrine and noradrenaline concentrations are not affected by the infusion of different remifentanil target concentrations.

Trial registration

The trial was registered at http://www.chictr.org.cn(ChiCTR1800019393, 8, Nov, 2018).

Comparison of vital capacity rapid inhalation and tidal ventilation induction with sevoflurane in adults: a prospective cohort study

Vital capacity rapid inhalation induction (VCRII) results in faster achievement of desired minimum alveolar concentration while reducing the incidence of excitatory phenomenon compared to conventional incremental technique. This study aimed to determine whether the VCRII can achieve faster induction of anesthesia in adults compared to the traditional tidal ventilation (TV) technique. Following the approval from the Institutional Ethics Committee, Amala Institute of Medical Sciences, with an approval No. AIMSIEC/07/2017, on July 1, 2017, 51 adults belonging to American Society of Anesthesiologists physical status I–II, undergoing elective surgery at a tertiary care teaching hospital were prospectively assigned to two groups: 25 in VCRII (38.3 ± 13.3 years old, 20 (80%) females) and 26 in TV inhalation induction (35.2 ± 11.9 years old, 17 (65%) females) using 8% sevoflurane in 66% nitrous oxide. The induction time, such as time (in seconds) to the cessation of voluntary finger tapping, time to loss of eyelash reflex, time to return of regular breathing, the return of conjugate gaze, was measured. The primary outcome was time to induction as defined by time to loss of eyelash reflex. Hemodynamic effects of both methods were compared at baseline and 1, 3, 5, 10, 15-minute intervals from induction. Induction was significantly faster in the VCRII group compared with the TV group in all the measured parameters. Hemodynamic parameters were comparable in both the groups. VCRII resulted in a faster induction time compared to the TV technique in adults.

[Short term olfactory memory and olfactory function after inhalation anesthetic agents: a randomized clinical trial]

BACKGROUND AND OBJECTIVES

This clinical trial aimed to evaluate the effects of two different inhalation anesthetic agents on postoperative olfactory memory and olfactory function in patients who underwent micro laryngeal surgery.

METHODS

This randomized prospective controlled study consisted of 102 consecutive patients with a voice disorder. The patients underwent micro laryngeal surgery for voice disorders under general anesthesia. Patients who did not meet inclusion criteria and/or declined to participate (n=34) were excluded from the study. Patients were divided into two groups. Four patients from Group 1 and four patients from Group 2 were lost to follow-up. Group 1 (n=30) received sevoflurane, and Group 2 (n=30) received desflurane during anesthesia. We compared the results by performing the pre-op and post-op Connecticut Chemosensory Clinical Research Center Olfactory test.

RESULTS

Thirty-three patients (55%) were male and 27 (45%) were female. The mean age was 48.18±13.88 years (range: 19-70 years). Preoperative and postoperative olfactory functions did not show a significant difference within the groups postoperatively (p> 0.05). Preoperative and postoperative olfactory memory showed a significant decrease 3hours after the surgery (p <0.05).

CONCLUSIONS

Olfactory functions and memory were not affected by desflurane in the early postoperative period. Although sevoflurane did not affect olfactory functions, it had a temporary negative effect on olfactory memory in the early postoperative period.

Short term olfactory memory and olfactory function after inhalation anesthetic agents: a randomized clinical trial

Background and objectives

This clinical trial aimed to evaluate the effects of two different inhalation anesthetic agents on postoperative olfactory memory and olfactory function in patients who underwent micro laryngeal surgery.

Methods

This randomized prospective controlled study consisted of 102 consecutive patients with a voice disorder. The patients underwent micro laryngeal surgery for voice disorders under general anesthesia. Patients who did not meet inclusion criteria and/or declined to participate (n = 34) were excluded from the study. Patients were divided into two groups. Four patients from Group 1 and four patients from Group 2 were lost to follow-up. Group 1 (n = 30) received sevoflurane, and Group 2 (n = 30) received desflurane during anesthesia. We compared the results by performing the pre-op and post-op Connecticut Chemosensory Clinical Research Center Olfactory test.

Results

Thirty-three patients (55%) were male and 27 (45%) were female. The mean age was 48.18 ± 13.88 years (range: 19‒70 years). Preoperative and postoperative olfactory functions did not show a significant difference within the groups postoperatively (p > 0.05). Preoperative and postoperative olfactory memory showed a significant decrease 3 hours after the surgery (p < 0.05).

Conclusions

Olfactory functions and memory were not affected by desflurane in the early postoperative period. Although sevoflurane did not affect olfactory functions, it had a temporary negative effect on olfactory memory in the early postoperative period.

Minimum Alveolar Concentration of Sevoflurane with Cisatracurium for Endotracheal Intubation in Neonates

Background

Sevoflurane inhalation induction is widely used in pediatric anesthesia, but the minimum alveolar concentration for endotracheal intubation (MAC_EI) when combined with neuromuscular blockade in neonates has been largely unexplored. This study assessed the MAC_EI of sevoflurane combined with cisatracurium in neonates.

Material/Methods

Anesthesia induction was commenced by inhaling 4% sevoflurane with 2 l/min of 100% oxygen via mask. Neonates were administered cisatracurium 0.2 mg/kg followed by adjustment of inspired sevoflurane to target end-tidal concentration based on intubation condition of the preceding subject. When the steady-state end-tidal sevoflurane concentration target was maintained for at least 15 min, endotracheal intubation by direct laryngoscope was performed. The intubation condition was considered failed if either heart rate (HR) after intubation increased by 20% or mean arterial blood pressure (MAP) by 30% or more than that before intubation. Otherwise, the intubation condition was regarded as successful. Dixon’s up-and-down method was used with 0.2% as the step size to determine the target end-tidal sevoflurane concentration.

Results

The MAC_EI of sevoflurane combined with cisatracurium in neonates was 2.76±0.24%. Using probit analysis, the 50% effective end-tidal sevoflurane concentration (ED₅₀) for successful condition of endotracheal intubation was 2.61% (95%CI 2.07–2.88%) and the 95% effective end-tidal sevoflurane concentration (ED₉₅) was 3.28% (95%CI 2.95–7.19%). Hypotension and bradycardia occurred in 2 neonates during induction.

Conclusions

Sevoflurane combined with cisatracurium is feasible and effective for intubation in neonates, and the MAC_EI of sevoflurane in this subpopulation is 2.76±0.24%. However, cardiovascular adverse effects should be taken into consideration.

Sevoflurane induces cognitive impairments via the MiR-27b/LIMK1-signaling pathway in developing rats

Exposure to sevoflurane in neonatal rats could induce learning deficits and abnormal social behaviors, but the specific molecular mechanism is unknown. Postnatal day-7 SD rats were treated with 3% sevoflurane plus 30% oxygen/air or 30% oxygen/air. As the rats grew, the Morris water maze (MWM) and fear conditioning tests were performed to evaluate cognitive function, while the expression of LIMK1 was analyzed by western blot. Luciferase reporter assay was performed to investigate the interaction between LIMK1 and miR-27b. The expression of miR-27b was measured by real-time polymerase chain reaction (PCR) after exposure to sevoflurane. Once the miR-27b inhibitor was transfected into the neurons, the expression of LIMK1 was analyzed by real-time PCR and western blot. Exposure to sevoflurane in neonatal rats induced memory and learning impairments according to the MWM and fear conditioning tests. Sevoflurane increased the expression of miR-27b and reduced the expression of LIMK1 in the brain tissues of rats compared to the control group. The results of the luciferase reporter assay showed that LIMK1 was a direct target of miR-27b. In the primary neurons, the inhibition of miR-27b could reverse the down-regulating effects of sevoflurane on LIMK1 expression. We suggest that sevoflurane-induced learning and memory impairments in rats might be mediated via the miR-27b-LIMK1-signaling pathway.

Does sevoflurane add to outpatient procedural sedation in children? A randomised clinical trial

BACKGROUND

There is little evidence concerning the effect of sevoflurane in outpatient procedural sedation, especially in children. We hypothesised that the addition of sevoflurane to a sedation regimen improves children's behaviour with minimal adverse events.

METHODS

This is a randomised, triple-blind clinical trial conducted on an outpatient basis. Participants were 27 healthy children aged 4 to 6 years, who previously refused dental treatment with non-pharmacologic methods. All participants received oral midazolam (0.5 mg/kg, maximum 20 mg) and oral ketamine (3 mg/kg, maximum 50 mg) and, in addition: Group MK - 100% oxygen; Group MKS - inhalational sevoflurane at a sedative dose (final expired concentration between 0.3 and 0.4%). Dental appointments were video recorded for assessment of the children's sleep patterns, crying, movements, and overall behaviour during the procedure with the Houpt scale. Intra- and post-operative adverse events were systematically reported. Data were analysed by bivariate analyses in the IBM SPSS v. 19, at a significance level of 5%.

RESULTS

MK (n = 13) and MKS (n = 14) did not differ regarding the Houpt scores (P > 0.05), but 53.8% of children in the MK group showed hysterical and continuous crying at the time of the local anaesthesia injection, compared to 7.1% of children in the MKS group (P = 0.01; phi = 0.5). There was a trend toward less crying and movement over time during the dental appointment in the MKS group (P = 0.48). Minor adverse events were observed in 10 MK children and 4 MKS children (P = 0.01).

CONCLUSIONS

The addition of sevoflurane to oral midazolam-ketamine improved the children's crying behaviour during local anaesthetic administration, and did not increase the occurrence of adverse events.

TRIAL REGISTRATION

Clinical Trials NCT02284204 . Registered 5 October 2014.

Exposure to Sevoflurane Affects the Development of Parvalbumin Interneurons in the Main Olfactory Bulb in Mice

Sevoflurane is widely used in adult and pediatric patients during clinical surgeries. Although studies have shown that exposure to sevoflurane impairs solfactory memory after an operation, the neuropathological changes underlying this effect are not clear. This study detected the effect of sevoflurane exposure on the development of calcium-binding proteins-expressing interneurons in the main olfactory bulb (MOB). We exposed neonatal mice to 2% sevoflurane at two different developmental time points and found that exposing mice to sevoflurane at postnatal day (PD) 7 significantly decreased the expression of GAD67 and parvalbumin (PV) in the olfactory bulb (OB) but did not alter the expression of calretinin (CR) or calbindin D28k (CB). The number and dendritic morphology of PV-expressing interneurons in the MOB were impaired by exposure to sevoflurane at PD7. However, exposure to sevoflurane at PD10 had no effect on calcium-binding protein expression or the number and dendritic morphology of PV-expressing interneurons in the MOB. These results suggest that exposing neonatal mice to sevoflurane during a critical period of olfactory development affects the development of PV-expressing interneurons in the MOB.

The use of inhaled sevoflurane during operative hysteroscopy is associated with increased glycine absorption compared to intravenous propofol for maintenance of anesthesia

STUDY OBJECTIVE

To compare the effects of anesthesia maintenance drugs (inhaled sevoflurane versus intravenous propofol) used in general anesthesia on the absorption of glycine 1.5% solution during hysteroscopy.

DESIGN

Prospective comparative study.

SETTING

Tertiary care university hospital.

PATIENTS

One hundred fifteen women undergoing hysteroscopy.

INTERVENTIONS

Women were assigned to receive general anesthesia with inhaled sevoflurane (n = 77) or intravenous propofol (n = 38) to maintain anesthesia.

MEASUREMENTS

The primary endpoint was clinically relevant glycine 1.5% absorption (>1000 mL), while secondary endpoints were the median of glycine absorption, operative time, complications and the incidence of discontinuation of the hysteroscopic procedure due to excessive glycine 1.5% absorption.

MAIN RESULTS

Maintenance with sevoflurane produced significantly increased absorption of glycine 1.5% solution compared to intravenous anesthesia (264 vs 202 mL, P = .007). Clinically relevant absorption rates (>1000 mL) were observed in the sevoflurane group (P = .04) while none of the women receiving intravenous anesthesia reached this absorption level. No cases of severe post-operative hyponatremia (Na(1+)<125 mmol/L) or adverse events derived from glycine 1.5% absorption were reported. No major complications (such as perforations, severe hemorrhage or infection) were presented during the interventions.

CONCLUSIONS

The results of the present study show that the use of inhaled sevoflurane is associated with significantly increased glycine 1.5% absorption compared to intravenous propofol for the maintenance of anesthesia. However, further randomized controlled trials are needed to assess the possible mechanisms and risk factors involved in the higher absorption induced by sevoflurane.

μ-Opioid agonists for preventing emergence agitation under sevoflurane anesthesia in children: a meta-analysis of randomized controlled trials

BACKGROUND

Emergence agitation (EA) is an adverse effect after sevoflurane anesthesia in pediatric patients. The effectiveness of prophylactic μ-opioid agonists fentanyl, remifentanil, sufentanil, and alfentanil in preventing EA is debatable.

METHODS

A literature search was conducted to identify clinical trials that observed the effect of μ-opioid agonists fentanyl, remifentanil, sufentanil, and alfentanil on preventing EA in pediatric patients under sevoflurane anesthesia. The statistical software RevMan 5.3 was used for meta-analysis. Data from each study were combined using the relative ratio (RR), weighted mean differences, and their associated 95% confidence intervals. I(2) was used to evaluate heterogeneity. Subgroup analysis was conducted to investigate the possible influences of patient age, adenotonsillectomy, premedication, N2 O, propofol, and regional block/local anesthetics on preventing EA with prophylactic administration of μ-opioid agonists. Publication bias was checked using funnel plots and Begg's test.

RESULTS

This meta-analysis showed the inclusion of 19 randomized controlled trials with 1528 patients (857 patients received μ-opioid agonists therapy and 671 patients had placebo). The pooled data indicated that prophylactic μ-opioid agonists fentanyl, remifentanil, sufentanil, and alfentanil significantly decreased the incidence of EA [RR = 0.49 (0.38, 0.64), I(2) = 42%, P = 0.04; RR = 0.57 (0.33, 0.99), I(2) = 37%, P = 0.19; RR = 0.18 (0.08, 0.39), I(2) = 0%, P = 0.98; and RR = 0.56 (0.40, 0.78), I(2) = 6%, P = 0.34, respectively]. All subgroup analyses strengthened the proof for lower incidence of EA under sevoflurane anesthesia after fentanyl administration. A possibility of publication bias was detected in the fentanyl group.

CONCLUSIONS

This meta-analysis suggested that prophylactic μ-opioid agonists fentanyl, remifentanil, sufentanil, and alfentanil could significantly decrease the incidence of EA under sevoflurane anesthesia in children compared to placebo. Considering the limitations of the included studies, more clinical studies are required.

Clinical effects of sevoflurane anesthesia induction with a portable inhalational anesthetic circuit in pediatric patients

INTRODUCTION

Pediatric anesthesia induction with sevoflurane usually needs a special vaporizer and gas source, which limits its use to the operating room (OR). Many children feel anxious and cry when entering the OR because of being separated from their parents, which impairs anesthesia safety and their physical and mental health. In this study, we used a portable circuit to perform sevoflurane anesthesia induction outside the OR, assessed its effects and compared them with those of ketamine anesthesia in pediatric patients.

MATERIAL AND METHODS

One hundred children had anesthesia induced with either sevoflurane (sevoflurane group) through the portable inhalational anesthetic circuit, or ketamine by intramuscular injection (ketamine group), then were transferred to the OR. Peak inspired concentration (Cp) and steady state concentration (Cs) of sevoflurane were measured. Heart rate (HR) and saturation of peripheral oxygen (SpO2) were monitored. Time for anesthesia induction, awakening, leaving the OR and duration of the operation were recorded. The patients' reaction during anesthesia was also analyzed.

RESULTS

The Cp and Cs of sevoflurane were correlated with bodyweight. Compared with the ketamine group, the sevoflurane group showed shorter time for anesthesia induction (28 ±7 s vs. 195 ±34 s, p < 0.0001), awakening (11.2 ±3.6 s vs. 63.5 ±6.7 s, p < 0.0001) and leaving the OR (20.5 ±5.6 s vs. 43.4 ±10.6, p < 0.0001), less noncooperation during anesthesia induction (10% vs. 80%, p < 0.0001), lower HR (130 ±16 beats/min vs. 143 ±19 beats/min, p = 0.0004) and higher SpO2 (98.9 ±0.9% vs. 96.1 ±2.5%, p < 0.0001) on arrival at the OR.

CONCLUSIONS

Pediatric anesthesia induction by sevoflurane with the portable inhalational anesthetic circuit is convenient, safe and effective outside the OR.

Renal and hepatic integrity in long-term sevoflurane sedation using the anesthetic conserving device: a comparison with intravenous propofol sedation in an animal model

INTRODUCTION

Critically ill patients are sedated with intravenous agents because the use of inhaled agents is limited by their potential risk of toxicity. Increasing levels of inorganic fluorides after the metabolism of these agents have been considered potentially nephrotoxic. However, hepatic involvement after prolonged administration of sevoflurane has not yet been studied. The present study evaluated the potential renal and hepatic toxicity caused by prolonged administration (72h) of sevoflurane.

METHODS

For this experimental, prospective, randomized, controlled trial, 22 Landrace x Large-White female pigs were randomly assigned to two groups: intravenous propofol (P) or inhaled sevoflurane via the AnaConDa™ device (S, end-tidal 2.5 vol%). The P group remained sedated for 108h with propofol. In the S group, sevoflurane was administered for 72h and then changed to propofol for the remaining 36h in order to observe the kinetics of fluoride after discontinuation of sevoflurane. Serum creatinine was the primary outcome variable, but inorganic fluoride concentrations and other renal, hepatic, and cardiorespiratory variables were also measured.

RESULTS

Both groups of animals were comparable at baseline. No differences were found between the two groups for plasma creatinine and urea or creatinine clearance throughout the study. Fluoride levels were significantly higher in the sevoflurane group. No correlation was found between inorganic fluoride and serum creatinine values. No significant differences were observed for hepatic function. Hemodynamic, respiratory, and blood gas variables were comparable between the groups.

CONCLUSIONS

Long-term sedation with sevoflurane using AnaConDa™ or propofol does not negatively affect renal or hepatic function.

Novel nanosynthesis of In2O3 and its application as a resistive gas sensor for sevoflurane anesthetic

A novel non-aqueous sol–gel route for synthesizing pure In₂O₃ nanoparticles using indium acetylacetonate and n-butylamine under solvothermal conditions is herein proposed.

Induction of murine TNBS colitis is strictly controlled by a modified method using continuous inhalation anesthesia with sevoflurane

BACKGROUND

Trinitrobenzenesulfonic acid (TNBS)-induced colitis is one of the most widely used experimental colitis models. However, there is no standard procedure for inducing colitis by TNBS because it is difficult to achieve a uniform distribution of colitis. We have developed a modified method of murine TNBS-induced colitis that involves inhalation anesthesia with sevoflurane combined with both single and repeated TNBS administrations.

AIMS

To compare the usefulness of our newly developed method for inducing murine TNBS-induced colitis with that of conventional intraperitoneal anesthesia.

METHODS

TNBS in ethanol was administered to C57BL/6J mice held in an inverted vertical position either under continuous inhalation anesthesia with sevoflurane, in accordance with our newly developed method, or by intraperitoneal injection with 2.5 % avertin, in accordance with the conventional procedure. Body weight change, cytokine profile, and histological findings were examined during the course of colitis.

RESULTS

The dispersion of anesthesia time, TNBS retention time, and nadir weight during the course of colitis was decreased using the newly developed method compared with the conventional procedure. Optimization of the modified TNBS-induced colitis, as evidenced by the predominant expression of Th1 and Th17 cytokines on day 7, was attained by the injection of 2.25 mg TNBS in 55 % ethanol. Regulation of the TNBS retention time using inhalation anesthesia with sevoflurane allowed strict control of the disease severity of TNBS-induced colitis. Using the modified method we were also able to develop a chronic TNBS-induced colitis model by repeated TNBS administration without excessive mortality of the mice.

CONCLUSIONS

Our modified method for murine TNBS-induced colitis using continuous inhalation anesthesia with sevoflurane provides a better experimental colitis model following both single and repeated TNBS administrations.

Mapping the sevoflurane-binding sites of calmodulin

General anesthetics, with sevoflurane (SF) being the first choice inhalational anesthetic agent, provide reversible, broad depressor effects on the nervous system yet have a narrow margin of safety. As characterization of low-affinity binding interactions of volatile substances is exceptionally challenging with the existing methods, none of the numerous cellular targets proposed as chief protagonists in anesthesia could yet be confirmed. The recognition that most critical functions modulated by volatile anesthetics are under the control of intracellular Ca²⁺ concentration, which in turn is primarily regulated by calmodulin (CaM), motivated us for characterization of the SF–CaM interaction. Solution NMR (Nuclear Magnetic Resonance) spectroscopy was used to identify SF-binding sites using chemical shift displacement, NOESY and heteronuclear Overhauser enhancement spectroscopy (HOESY) experiments. Binding affinities were measured using ITC (isothermal titration calorimetry). SF binds to both lobes of (Ca²⁺)₄-CaM with low mmol/L affinity whereas no interaction was observed in the absence of Ca²⁺. SF does not affect the calcium binding of CaM. The structurally closely related SF and isoflurane are shown to bind to the same clefts. The SF-binding clefts overlap with the binding sites of physiologically relevant ion channels and bioactive small molecules, but the binding affinity suggests it could only interfere with very weak CaM targets.

A novel approach to assess hemorrhagic shock severity using the arterially determined left ventricular isovolumic contraction period

Recently, the ventilatory variation in pre-ejection period (ΔPEP) was found to be useful in the prediction of fluid-responsiveness of patients in shock. In the present study we investigated the behavior of the ventilation-induced variations in the systolic timing intervals in response to a graded hemorrhage protocol. The timing intervals studied included the ventilatory variation in ventricular electromechanical delay (ΔEMD), isovolumic contraction period (determined from the arterial pressure waveform, ΔAIC), pulse travel time (ΔPTT), and ΔPEP. ΔAIC and ΔPEP were evaluated in the aorta and carotid artery (annotated by subscripts Ao and CA) and were compared with the responses of pulse pressure variation (ΔPPAo) and stroke volume variation (ΔSV). The graded hemorrhage protocol, followed by resuscitation using norepinephrine and autologous blood transfusion, was performed in eight anesthetized Yorkshire X Landrace swine. ΔAICAo, ΔAICCA, ΔPEPAo, ΔPEPCA, ΔPPAo, ΔPPCA, and ΔSV showed significant increases during the graded hemorrhage and significant decreases during the subsequent resuscitation. ΔAICAo, ΔAICCA, ΔPEPAo, and ΔPEPCA all correlated well with ΔPPAo and ΔSV (all r ≥ 0.8, all P < 0.001). ΔEMD and ΔPTT did not significantly change throughout the protocol. In contrast with ΔPEPAo, which was significantly higher than ΔPEPCA (P < 0.01), ΔAICAo was not different from ΔAICCA. In conclusion, ventilation-induced preload variation principally affects the arterially determined isovolumic contraction period (AIC). Moreover, ΔAIC can be determined solely from the arterial pressure waveform, whereas ΔPEP also requires ECG measurement. Importantly, ΔAIC determined from either the carotid or aortic pressure waveform are interchangeable, suggesting that, in contrast with ΔPEP, ΔAIC may be site independent.

Early life exposure to sevoflurane impairs adulthood spatial memory in the rat

Sevoflurane is a general anesthetic commonly used in the pediatric setting because it is sweet-smelling, nonflammable, fast acting and has a very short recovery time. Although recent clinical data suggest that early anesthesia exposure is associated with subsequent learning and memory problems, it is difficult to determine the exact scope of developmental neurotoxicity associated with exposure to specific anesthetics such as sevoflurane. This is largely due to inconsistencies in the literature. Thus, in the present studies we evaluated the effect of early life exposure to sevoflurane (1%, 2%, 3% or 4%) on adulthood memory impairment in Sprague-Dawley rats. Animals were exposed to different regimens of sevoflurane anesthesia on postnatal days (PNDs) 3, 7, or 14 or at 7 weeks (P7W) of age and spatial memory performance was assessed in adulthood using the Morris Water Maze (MWM). Rats exposed to sevoflurane exhibited significant memory impairment which was concentration and exposure duration dependent. Disruption of MWM performance was more severe in animals exposed on both PNDs 3 and 7 than in animals exposed on both PNDs 3 and 14. The younger the animal's age at the time of exposure, the more significant the effect on later MWM performance. Compared to the neonates, animals exposed at P7W were relatively insensitive to sevoflurane: memory was impaired in this group only after repeated exposures to low doses or single exposures to high doses. Early life exposure to sevoflurane can result in spatial memory impairments in adulthood and the shorter the interval between exposures, the greater the deficit.

Surgery-induced behavioral changes in aged rats

Elderly patients may experience impairments in cognition or mood following surgery. To study the development and underlying mechanisms of these postoperative behavioral changes, young (3 months) and aged (18-20 months) male rats were subjected to abdominal surgery followed by behavioral testing during a period of 6 weeks. Microglia activation (IBA-1) and neurogenesis (DCX) were immunohistochemically determined. In separate experiments, the effects of anesthesia and the cytokine response (IL-6) following surgery were evaluated. Increased age was associated with changes in affective behavior, decreased cognitive flexibility and increased microglia activation as well as increased weight loss and plasma IL-6 following surgery. No effects of surgery on cognition were observed at either age. However, aged rats displayed long-term changes in affective behavior and had increased microgliosis in the CA1 hippocampal region following surgery. Microglia activation following surgery was positively correlated to parameters of behavior and spatial learning. These findings support the hypothesis that elderly patients have an increased behavioral and (neuro)inflammatory response to surgery and these factors may be related.

General anesthesia as a possible GABAergic modulator affects visual processing in children

Gamma-Aminobutyric Acid (GABA) inhibitory interneurons play an important role in visual processing, as is revealed by studies administering drugs in human and monkey adults. Investigating this process in children requires different methodologies, due to ethical considerations. The current study aimed to investigate whether a new method, being general anesthesia using Sevoflurane, can be used to trace the effects of GABAergic modulation on visual brain functioning in children. To this aim, visual processing was investigated in children aged 4–12 years who were scheduled for minor urologic procedures under general anesthesia in day-care treatment. In a visual segmentation task, the difference in Event-Related Potential (ERP) response to homogeneous and textured stimuli was investigated. In addition, psychophysical performance on visual acuity and contrast sensitivity were measured. Results were compared between before and shortly after anesthesia. In two additional studies, effects at 1 day after anesthesia and possible effects of task-repetition were investigated. ERP results showed longer latency and lower amplitude of the Texture Negativity (TN) component shortly after compared to before anesthesia. No effects of anesthesia on psychophysical measurements were found. No effects at 1 day after anesthesia or of repetition were revealed either. These results show that GABAergic modulation through general anesthesia affects ERP reflections of visual segmentation in a similar way in children as benzodiazepine does in adults, but that effects are not permanent. This demonstrates that ERP measurement after anesthesia is a successful method to study effects of GABAergic modulation in children.

Efficacy of different concentrations of sevoflurane administered through a face mask for magnetic resonance imaging in children

BACKGROUND

The main aim of this study was to use a non-invasive method such as a face mask to maintain anesthesia in children during magnetic resonance imaging (MRI). The secondary aim was to ascertain hemodynamic-respiration parameters, recovery time and complications of anesthesia with the administration of different concentrations of sevoflurane.

METHODS

This prospective and randomized study included 96 ASA I-II children, aged 1-10, scheduled to undergo MRI with anesthesia with sevoflurane through a face mask. All patients were administered midazolam 0.5 mg·kg(-1) orally 30 min before anesthesia induction. Sevoflurane 8% was given to induce anesthesia under assisted-controlled ventilation for 2 min, and an intravenous route was opened on the hand. Three different concentrations of sevoflurane were administered through a face mask under spontaneous respiration to maintain anesthesia. A mixture of sevoflurane, oxygen, and air of 5 l·min(-1) was given through a face mask for anesthesia. Group 1 (n = 32) received 1.5% sevoflurane, Group 2 (n = 32) 1.25% sevoflurane, and Group 3 (n = 32) 1.0% sevoflurane. Recovery time, removal from the MRI room, postanesthesia care unit discharge data, and complications were also recorded. Heart rate, mean arterial pressure (MAP), peripheral oxygen saturation (SpO(2)), respiration rate, and anesthesia adequacy were recorded every 5 min from the time of induction until completion of the MRI.

RESULTS

All three groups were similar in demographic and hemodynamic respiratory features. MRI was successfully performed in 96.6% of all patients without additional intervention. Sevoflurane concentrations were increased for a short time in one patient in Group 1 and in two patients in Group 3. Oxygen flow was increased in one patient in Group 1 and in one patient in Group 2 as SpO(2) was lower than 95%. The mean time to eye opening (from discontinuation of sevoflurane to eye opening) was 155.8 ± 50.0 s in Group 1, 89.5 ± 16.0 s in Group 2, and 53.5 ± 10.0 s in Group 3; differences between the groups were statistically significant (P = 0.001). Airways were not used on any of the patients, and none vomited or required endotracheal intubation or laryngeal mask anesthesia.

CONCLUSIONS

We believe that the administration of sevoflurane at a concentration of 1% via a face mask under spontaneous respiration may provide light anesthesia without complications to induce an unarousable sleep for children during MRI.