End-tidal Sevoflurane Research Articles

Sevoflurane Sparing Effect of Morphine in Tegus (Salvator merianae) – A Preliminary Study

This study aimed to determine the minimum anesthetic concentration (MAC) of sevoflurane in tegus (Salvator merianae) and the morphine-sparing effect on this variable. In a prospective, non-blinded, crossover study, MAC was first determined in 6 tegus under sevoflurane anesthesia alone (MACSEVO) and then following intramuscular administration of morphine (10 mg/kg), administered 3 hour before sevoflurane anesthesia (MACSEVO+MOR). A standard bracketing technique was applied to determine the MAC by an electrical supramaximal noxious stimulus (50 Hz, 30 mA) delivered at the base of the tail of the tegus. The end-tidal sevoflurane fraction was reduced or increased by 10% in any evidence of negative or positive motor responses, respectively. The MAC was calculated as the mean of the 2 highest successive sevoflurane concentrations that permitted positive responses and the 2 lowest that prevented positive responses. Heart rate, esophageal temperature, and noninvasive mean arterial blood pressure were assessed every 10 minutes. The MAC was significantly different between MACSEVO (2.41 ± 0.06%) and MACSEVO+MORF (1.88 ± 0.43%) (P = .007), with a mean ± SD morphine-induced reduction in the sevoflurane MAC of 22 ± 18% (P = .0158). Heart rate, mean arterial blood pressure, and esophageal temperature did not differ between groups or within groups over time. Results showed that intramuscular premedication with 10 mg/kg morphine produced a sevoflurane sparing effect in tegus with no significant impact on cardiovascular variables.

Laparoscopic versus Open Ovariectomy in Bitches: Changes in Cardiorespiratory Values, Blood Parameters, and Sevoflurane Requirements Associated with the Surgical Technique.

Simple SummaryLaparoscopic neutering techniques are widely used in veterinary medicine due to their numerous advantages compared to open ones. However, laparoscopy requires the creation of pneumoperitoneum to establish a working space, and it has been related to the occurrence of pathophysiological alterations. The objective of this study was to evaluate the potential global systemic changes associated to the establishment of the pneumoperitoneum in laparoscopic ovariectomy and to compare them with those determined in conventional open surgery in dogs. Additionally, we evaluated the gas anesthetic requirements based on the surgical technique. The results of our study suggested that the cardiorespiratory alterations related to pneumoperitoneum seemed to be well-tolerated and reversible after CO2 deflation. Regarding the anesthetic gas evaluation, we determined higher requirements during ovarian resection in the open ovariectomy group. In conclusion, laparoscopic neutering procedures should be currently recommended by veterinarians due to their lower invasiveness and resulting complications. Nevertheless, a thorough understanding of the changes associated with pneumoperitoneum is essential to plan and obtain an adequate perioperative management.The aim of this study was to examine the cardiorespiratory and blood changes associated with pneumoperitoneum (PNP) in laparoscopic ovariectomy (LAP Ove), as well as sevoflurane requirements, comparing them to those determined in open surgery (LPT Ove). The study was performed in 16 bitches submitted to LAP or LPT Ove. The cardiorespiratory and end-tidal sevoflurane concentration values were recorded as follows: at the beginning of surgery (T1), after the right ovary resection (T2), after the left ovary resection (T3), and after surgical closure (T4). Blood samples were taken before and after PNP. Among the cardiorespiratory parameters, no differences were observed in the values of end-tidal CO2, minute volume, and heart rate. In the LAP Ove group, a significant increase in inspiratory pressures and a decreased compliance were identified at T2 and T3. Significant higher arterial pressure values were observed in both groups at T2 and T3, with this increase especially marked at T2 in the LPT Ove group. Sevoflurane requirements were significantly higher in the LPT group during ovarian resection. Finally, in terms of the hematochemical parameters, statistical differences were recorded between pre- and post-operative assessments, but not between both surgical groups. The pathophysiological effects associated with PNP seemed to be transient and well-tolerated by healthy dogs.

Sevoflurane concentration for cannulation in developmental disabilities

ObjectiveThe goal of this study was to compare the end-tidal sevoflurane concentration and time for intravenous cannulation at induction of anesthesia using sevoflurane with or without nitrous oxide in healthy children and in those with developmental disabilities.MethodsNormal and developmentally disabled children were anesthetized by inhalation of sevoflurane with nitrous oxide or with nitrous oxide-free oxygen, and intravenous cannulae were introduced. Nitrous oxide was stopped after loss of consciousness. The following parameters were recorded for each patient: age, gender, height, weight, BMI, duration of intravenous cannulation, end-tidal concentration of sevoflurane at the completion of intravenous cannulation, and use of nitrous oxide.For each parameter except gender, p-value were calculated by one-way analysis of variance (ANOVA). For gender, p-value were calculated using the Fisher method. Two-way ANOVA was performed to evaluate the effect of patient health status and nitrous oxide use on the end-tidal concentrations of sevoflurane and the time required for intravenous cannulation.ResultsThe end-tidal sevoflurane concentrations at the completion of the intravenous cannulation had received a significant main effect of the factor "the use of nitrous oxide" (F(1,166) = 25.8, p < 0.001, η2 = 0.13) and a small effect of the factor "the patient health status" (F(1,166) = 0.259, p = 0.611, η2 = 0.001). However, the time required for intravenous cannulation was not significantly affected by either of the two factors, "the use of nitrous oxide" (F(1,166) = 0.454, p = 0.501, η2 = 0.003) and "the patient health status" (F(1,166) = 0.308, p = 0.579, η2 = 0.002).ConclusionsBetween the healthy children and the children with developmental disabilities, no significant differences in the time required for the intravenous cannulation from the beginning of anesthetic induction. However, the end-tidal sevoflurane concentrations at the completion of the intravenous cannulation was significantly different. Sevoflurane in alveoli might be diluted by nitrous oxide.

Comparison of recovery times by using bispectral index monitoring versus end-tidal agent concentration monitoring in patients undergoing inhalational general anaesthesia.

Background and Aims:End-tidal anaesthetic gas concentration (ETAG) and bispectral index (BIS) are both used to monitor depth of anaesthesia. Maintaining an accurate depth of anaesthesia helps in early post-operative recovery. This study compared the recovery times from sevoflurane–nitrous oxide anaesthesia using ETAG monitoring with BIS monitoring.Methods:Four hundred and two patients undergoing elective surgeries under sevoflurane- nitrous oxide anaesthesia were enroled in this double blinded parallel group prospective randomised trial and allocated into two groups. The depth of anaesthesia was monitored using BIS in BIS group (n = 202) and end-tidal sevoflurane concentration (EtSevo) in ETAG group (n = 200). The time to extubation and recovery were compared between the groups. Parametric, non-parametric and categorical variables were compared using Student’s ‘t’ test, Wilcoxon’s rank sum test and Chi-square test, respectively.Results:Time to extubation (min) [BIS group – 10, 5; ETAG group – 10, 5 (median, inter-quartile range, IQR), P = 0.32] and time to recovery (min) [BIS group – 14, 6; ETAG group – 13.5, 7 (median, IQR), P = 0.34] did not differ significantly between the two groups. The EtSevo concentration (vol%) was significantly higher in the BIS group at 5 min [BIS group – 1.2, 0.4; ETAG group – 1.0, 0.4 (median, IQR), P < 0.001], 30 min [BIS group – 1.1, 0.4; ETAG group – 1.0, 0.3 (median, IQR), P = 0.002] and 120 min [BIS group – 1.11 ± 0.28; ETAG group – 0.96 ± 0.27 (mean ± standard deviation), P = 0.014] after induction of anaesthesia.Conclusions:BIS and ETAG monitoring are associated with comparable recovery profiles. ETAG monitoring is associated with significantly less sevoflurane consumption.

Whole-exome sequencing reveals genetic variations in humans with differential sensitivity to sevoflurane：A prospective observational study

BackgroundThe anesthesia sensitivity is heterogeneous both in animals and humans, while the underlying molecular mechanism has not yet been determined. Here, for the first time, we conducted a prospective observational study to test whether genetic variations contribute to the differential sensitivity to sevoflurane in humans. MethodsFive hundred patients who underwent abdominal surgeries were included. The end-tidal sevoflurane concentration (ETsevo) was adjusted to maintain Bispectral index (BIS) value between 40 and 60. The mean ETsevo from 20 min after endotracheal intubation to 2 h after the beginning of surgery was calculated for each patient. These patients were further divided into high sensitivity group (mean - SD, H group) and low sensitivity group (mean + SD, L group) to investigate the genetic variants related to the differential sensitivity to sevoflurane by whole-exome sequencing (WES) and genome-wide association study (GWAS) in karyocyte from peripheral blood. ResultsThe mean ETsevo of these 500 patients was 1.60% ± 0.34%. After pairing, 55 patients from H group and 59 patients from L group were selected for WES (ETsevo of H group: 1.06% ± 0.13% vs. ETsevo of L group: 2.17% ± 0.16%, P < 0.001), respectively. Finally, FAT atypical cadherin 2 (FAT2, SNP rs174272, rs174271, and rs174261), acireductone dioxygenase 1 (ADI1, SNP rs117278), NEDD4 E3 ubiquitin protein ligase (NEDD4, SNP rs70048, rs70049, and rs70056), and FAD dependent oxidoreductase domain containing 2 (FOXRED2, SNP rs144281) were found to be associated with sevoflurane sensitivity. ConclusionsGenetic variations may contribute to the differential sensitivity to sevoflurane among humans.

Single-injection caudal thoracic paravertebral block improves pain control and recovery quality in female dogs undergoing unilateral radical mastectomy: a randomized controlled trial.

To test clinical and analgesic effects of a single-injection caudal thoracic paravertebral block (TPVB) after localization of the thoracic paravertebral space with a loss-of-resistance to air injection technique in female dogs undergoing unilateral radical mastectomy. 14 client-owned dogs. Dogs were premedicated with methadone, anesthetized with propofol and sevoflurane, and randomly assigned to receive a TPVB or no block preoperatively. Rescue analgesia with fentanyl and methadone was provided on the basis of cardiovascular responses during surgery and postoperative pain scores assigned with a validated pain scale. Required dose of rescue opioids; mean end-tidal sevoflurane concentration; episodes of hypotension, bradycardia, and other complications; quality of recovery scores; and postoperative pain scores were compared between groups. Median intraoperative fentanyl doses were 0 µg/kg (range, 0 to 2 µg/kg) and 4 µg/kg (range, 2 to 6 µg/kg) for the TPVB and control groups, respectively. Median postoperative methadone doses were 0 mg/kg (range, 0 to 0.2 mg/kg) and 0.6 mg/kg (range, 0.4 to 0.6 mg/kg) for the TPVB and control groups, respectively. Recovery scores and pain scores assigned at the time of and 1 hour after extubation were significantly lower in the TPVB group than in the control group. A single-injection caudal TPVB improved pain control and recovery quality in female dogs undergoing unilateral radical mastectomy. Because the TPVB involves only a single injection, does not take long to perform, and requires only readily available low-cost equipment, the technique may be a valuable option in both referral and first-opinion practice.

Monitoring the effects of automated gas control of sevoflurane versus target-guided propofol infusion on hemodynamics of liver patients during liver resection. A randomized controlled trial.

Cirrhotic patients are prone to hypotension during anesthesia. The primary aim of the study was to compare the effects of automated gas control (AGC) of sevoflurane and target-controlled infusion (TCI) of propofol on systemic and cardiac hemodynamics in hepatitis C cirrhotic patients undergoing surgery. The secondary aim was to compare the recovery, complications, and costs between the two groups. This was a randomized controlled trial in adults with hepatitis C cirrhosis (Child A) who underwent open liver resection and received AGC (n = 25) or TCI (n = 25). AGC was initially set at FiO2 40% and end-tidal sevoflurane (ET SEVO) at 2.0% with a fresh gas flow of 300 mL/min. TCI of propofol was given using Marsh pharmacokinetic mode with an initial propofol target concentration (Cpt) of 4 μg/mL. Bispectral index score (BIS) was maintained between 40 and 60. Invasive arterial blood pressure (IBP), electrical cardiometry (EC), cardiac output (CO), and systemic vascular resistance (SVR), Fi SEVO, ET SEVO, propofol Cpt, and effect-site concentration (Ce) were recorded. IBP and EC CO, and SVR were least affected by TCI propofol. Only one (4.00%) patient required vasopressors with TCI vs. 4 (16.00%) with AGC (χ2 (Y) (df = 1) = 0.88, P (Y) = 0.34). There was no delayed recovery, hypoxia, or awareness; however, ICU stay was shorter with TCI, (P = 0.006). BIS and EC guided median of ET SEVO was 1.90%, Fi SEVO was 2.10% with AGC, and propofol Cpt and Ce were 3.00 μg/dL with TCI. Only 0.14 [0.12-0.15] mL/min of SEVO was consumed with AGC and 0.87 [0.85-0.97] mL/min propofol with TCI. The cost was higher with TCI, P < 0.00. Both techniques are well tolerated hemodynamically, but TCI-propofol was found to be hemodynamically better. The recovery and complications were comparable in both groups, but TCI Propofol infusion was costlier.

Minimizing sevoflurane wastage by sensible use of automated gas control technology in the flow-i workstation: an economic and ecological assessment

Both ecological and economic considerations dictate minimising wastage of volatile anaesthetics. To reconcile apparent opposing stakes between ecological/economical concerns and stability of anaesthetic delivery, new workstations feature automated software that continually optimizes the FGF to reliably obtain the requested gas mixture with minimal volatile anaesthetic waste. The aim of this study is to analyse the kinetics and consumption pattern of different approaches of sevoflurane delivery with the same 2% end-tidal goal in all patients. The consumption patterns of sevoflurane of a Flow-i were retrospectively studied in cases with a target end-tidal sevoflurane concentration (Etsevo) of 2%. For each setting, 25 cases were included in the analysis. In Automatic Gas Control (AGC) regulation with software version V4.04, a speed setting 6 was observed; in AGC software version V4.07, speed settings 2, 4, 6 and 8 were observed, as well as a group where a minimal FGF was manually pursued and a group with a fixed 2 L/min FGF. In 45 min, an average of 14.5 mL was consumed in the 2L-FGF group, 5.0 mL in the minimal-manual group, 7.1 mL in the AGC4.04 group and 6.3 mL in the AGC4.07 group. Faster speed AGC-settings resulted in higher consumption, from 6.0 mL in speed 2 to 7.3 mL in speed 8. The Etsevo target was acquired fastest in the 2L-FGF group and the Etsevo was more stable in the AGC groups and the 2L-FGF groups. In all AGC groups, the consumption in the first 8 min was significantly higher than in the minimal flow group, but then decreased to a comparable rate. The more recent AGC4.07 algorithm was more efficient than the older AGC4.04 algorithm. This study indicates that the AGC technology permits very significant economic and ecological benefits, combined with excellent stability and convenience, over conventional FGF settings and should be favoured. While manually regulated minimal flow is still slightly more economical compared to the automated algorithm, this comes with a cost of lower precision of the Etsevo. Further optimization of the AGC algorithms, particularly in the early wash-in period seems feasible. In AGC mode, lower speed settings result in significantly lower consumption of sevoflurane. Routine clinical practice using what historically is called “low flow anaesthesia” (e.g. 2 L/min FGF) should be abandoned, and all anaesthesia machines should be upgraded as soon as possible with automatic delivery technology to minimize atmospheric pollution with volatile anaesthetics.

Improved postoperative recovery profile in pediatric oral rehabilitation with low-dose dexmedetomidine as an opioid substitute for general anesthesia: a randomized double-blind clinical trial.

BackgroundLow-dose dexmedetomidine may be a suitable alternative to opioids for pediatric ambulatory procedures under general anesthesia (GA). However, the recovery profile remains unclear. Herein, we aimed to evaluate the effects of low-dose dexmedetomidine on the recovery profile of children.MethodsSeventy-two children undergoing ambulatory oral rehabilitation under GA were randomly and equally distributed into two groups (D and F). Group D received an infusion of dexmedetomidine 0.25 µg/kg for 4 min for induction, followed by maintenance of 0.4 µg/kg/h. Group F received an infusion of fentanyl 1 µg/kg over 4 min for induction, followed by maintenance at 1 µg/kg/h. The primary outcome was the extubation time. The secondary outcomes were awakening time, end-tidal sevoflurane (ET-Sevo) requirement, change in hemodynamic parameters, Richmond Agitation–Sedation Scale (RASS), Children's Hospital of Eastern Ontario pain scale (CHEOPS) score, length of PACU stay, and incidence of adverse events.ResultsStatistically significant differences were observed in the recovery profile between the groups: the median time for extubation was 3.65 (3.44–6.2) vs. 6.25 (4.21–7) minutes in groups D vs. F (P = 0.001), respectively, while the corresponding awakening times were 19 (18.75–21) and 22.5 (22–24) minutes, respectively (P < 0.001). The mean ET-Sevo was low in group D (1.1 vs. 1.2; P < 0.001). The heart rate was significantly low across all time points in group D, without resulting in bradycardia. The median RASS and CHEOPS scores were also significantly lower in group D. No significant differences were observed in the mean arterial pressure, incidence of adverse events, or length of PACU stay.ConclusionLow-dose dexmedetomidine was more effective than fentanyl as an opioid substitute at providing a better recovery profile in pediatric ambulatory oral rehabilitation under GA. Dexmedetomidine also significantly reduced sevoflurane consumption without causing adverse events or prolonging hospital stay.

Effects of an open lung ventilatory strategy on lung gas exchange during laparoscopic surgery.

In general anaesthesia, early collapse of poorly ventilated lung segments with low alveolar ventilation-perfusion ratios occurs and may lead to postoperative pulmonary complications after abdominal surgery. An 'open lung' ventilation strategy involves lung recruitment followed by 'individualised' positive end-expiratory pressure titrated to maintain recruitment of low alveolar ventilation-perfusion ratio lung segments. There are limited data in laparoscopic surgery on the effects of this on pulmonary gas exchange. Forty laparoscopic bowel surgery patients were randomly assigned to standard ventilation or an 'open lung' ventilation intervention, with end-tidal target sevoflurane of 1% supplemented by propofol infusion. After peritoneal insufflation, stepped lung recruitment was performed in the intervention group followed by maintenance positive end-expiratory pressure of 12-15 cmH2O adjusted to maintain dynamic lung compliance at post-recruitment levels. Baseline gas and blood samples were taken and repeated after a minimum of 30 minutes for oxygen and carbon dioxide and for sevoflurane partial pressures using headspace equilibration. The sevoflurane arterial/alveolar partial pressure ratio and alveolar deadspace fraction were unchanged from baseline and remained similar between groups (mean (standard deviation) control group = 0.754 (0.086) versus intervention group = 0.785 (0.099), P = 0.319), while the arterial oxygen partial pressure/fractional inspired oxygen concentration ratio was significantly higher in the intervention group at the second timepoint (control group median (interquartile range) 288 (234-372) versus 376 (297-470) mmHg in the intervention group, P = 0.011). There was no difference between groups in the sevoflurane consumption rate. The efficiency of sevoflurane uptake is not improved by open lung ventilation in laparoscopy, despite improved arterial oxygenation associated with effective and sustained recruitment of low alveolar ventilation-perfusion ratio lung segments.

Metabolomics and Whole-Exome Sequencing in Patients with Differential Sensitivity to Sevoflurane: A Protocol for a Prospective Observational Trial.

Introduction: Different sensitivity to volatile anesthetics in Drosophila, nematodes and mice is related to mutation of energy metabolism genes. In clinical practice, we find that the end-tidal sevoflurane concentration (ETsevo) differs among patients at the same depth of anesthesia, indicating that the sensitivity to sevoflurane varies among patients. However, the underlying mechanism remains unclear. The sensitivity of an anesthetic is associated with the postoperative outcomes of patients and the mechanism of action of volatile anesthetics. We therefore propose this protocol to determine whether differences in metabolite profile and genetic variations contribute to patients’ sensitivity to volatile anesthetics. Methods and Analysis: This is a single-centre, prospective observational study. 720 patients undergoing abdominal surgery were included. General anesthesia was induced with inhaled sevoflurane, a bolus of sufentanil (0.2–0.4 μg/kg) and cis-atracurium (0.2–0.3 mg/kg). The end-tidal sevoflurane concentration (ETsevo) was adjusted to maintain a BIS (bispectral index) value between 40–60. The mean ETsevo from 20 min after endotracheal intubation to 2 h after the beginning of surgery (steady state) was calculated for each patient. Patients were further divided into a high-sensitivity group (mean ETsevo – SD) and a low-sensitivity group (mean ETsevo + SD) to investigate the sensitivity to sevoflurane. Cases were paired from the high-sensitivity group (group H) and low-sensitivity group (group L) according to age, sex, body mass index (BMI), ASA physical status classification, vital signs, BIS, ephedrine use, sufentanildose, and cis-atracurium dose at anesthesia induction and steady state. Differences in metabolite levels, single nucleotide polymorphisms (SNPs) and protein-coding gene sequence variations between group H and group L will be determined through plasma metabolomics, whole-exome sequencing (WES), genome-wide association study (GWAS), and bioinformatics analyses. These results will be analysed to determine the reasons for the differential sensitivity to sevoflurane in humans. Ethics and Dissemination: This prospective observational study protocol has received ethical approval from the Ethical Committee of West China Hospital of Sichuan University on May 19, 2017 (Approval No. 78). Informed consent will be obtained before patient enrolment. The results will be submitted to international peer-review journals. Trial Registration Number: ChiCTR1800014327.

Ultrasound assessment of the inferior vena cava in children: A comparison of sub-xiphoid and right lateral coronal views.

The inferior vena cava collapsibility index (IVCCI) has been used to assess the respiratory variation of the inferior vena cava (IVC) diameter and hence intravascular volume. The sub-xiphoid view (SXV) is the standard view to evaluate the IVC. The right lateral transabdominal view (RLV) has been shown in adults to be an alternative view to evaluate the IVC when the SXV is not feasible. The aim of the study was to compare IVC dimensions from these two views and thus determine whether the RLV view can be used instead of the SXV in pediatric patients. We conducted a single-center prospective observational crossover study. Study subjects were ASA physical status 1-2 children, 1-12 years of age scheduled for elective surgery under general anesthesia. Anesthesia was maintained by mask with spontaneous ventilation with end-tidal sevoflurane at 2%-5% after the induction of anesthesia. IVCCI was measured using M-mode in both the SXV and RLV. The study cohort included 50 children with a mean age of 5.1 years. The median value for the IVCCI-sx was 0.45 (IQR: 0.28-0.70) while the IVCCI-rl was 0.30 (0.19-0.5). The mean difference between the two groups was 0.12 (95% CI: 0.177-0.066, p < .001, two-tailed paired t-test). Spearman's rank correlation coefficient was 0.66. The univariate linear regression model was IVCCIsx=0.21 + 0.77 × IVCCIrl. IVCCIrl was lower than IVCCIsx. IVCCI measured from the right lateral view tended to overestimate the patient's fluid-responsiveness and therefore these two values are not interchangeable.

Optimum End Tidal Sevoflurane Concentration Required for Intravenous Cannulation in Children

Abstract Background Inhalation mask induction is a cornerstone of pediatric anesthesia. Because of their natural aversion to needles, healthy children are usually anesthetized by mask prior to intravenous insertion. The early insertion of an intravenous access provides a means for administering fluids and drugs if an untoward event occurs during inhalational induction. Sevoflurane is the inhalation agent most commonly used for mask inductions in pediatric anesthesia, having largely replaced halothane for this purpose. Objectives The aim of the study was to evaluate the optimum end tidal concentration of Sevoflurane at which an intravenous cannulation can be successfully attempted without movement in pediatric patients. Patients and Methods In this clinical trial, pediatric subjects of either sex aged 2-5 years, weighing 10-20 kg were included. Results Showed that an end tidal sevoflurane of 1.46% has 50% probability for successful intravenous cannulation without movement in children. Conclusion We conclude that an end tidal sevoflurane of 1.46% has 50% probability for successful intravenous cannulation in un- premedicated children aged between 2 and 5 years.

The Effects of Prophylactic Dexmedetomidine Administration on General Anesthesia Recovery Quality in Healthy Dogs Anesthetized With Sevoflurane and a Fentanyl Constant Rate Infusion Undergoing Elective Orthopedic Procedures.

To determine the effects of a dexmedetomidine slow bolus, administered prior to extubation, on recovery from sevoflurane-anesthesia and a fentanyl continuous rate infusion (CRI) in dogs undergoing orthopedic surgical procedures. Sixty-two client-owned, healthy dogs weighing 27.4 ± 11 kg undergoing elective orthopedic procedures were premedicated with: 0.1 mg/kg hydromorphone intramuscular, 0.05 mg/kg hydromorphone intravenously (IV) or 5 mcg/kg fentanyl IV. Following premedication, dogs were induced with propofol, administered locoregional anesthesia and maintained with sevoflurane and a fentanyl CRI (5–10 mcg/kg/hr). Dogs were randomly assigned to one of two treatment groups: 0.5 mcg/kg dexmedetomidine (DEX) or 0.5 ml/kg saline (SAL). Following surgery, patients were discontinued from the fentanyl CRI and administered DEX or SAL IV over 10 min. Following treatment, dogs were discontinued from sevoflurane and allowed to recover without interference. Recoveries were video recorded for 5 min following extubation and assessed by two blinded anesthesiologists using a visual analog scale (VAS; 0–10 cm) and a numerical rating scale (NRS; 1–10). Mean arterial pressure (MAP), heart rate (HR), pulse oximetry (SpO2), temperature, respiratory rate (RR), and end-tidal sevoflurane (EtSevo) and carbon dioxide (EtCO2) concentrations were recorded at specific time-points from induction to 5 min post-bolus administration and analyzed using linear mixed models. Fentanyl, propofol, and hydromorphone dose and the time to extubation were compared using an unpaired t-test. Differences in recovery scores between groups were evaluated with a Mann-Whitney test. Data reported as mean ± SD or median [interquartile range] when appropriate. A p < 0.05 was significant. There were no significant differences between groups in fentanyl, propofol, and hydromorphone dose, duration of anesthesia, intraoperative MAP, HR, RR, SpO2, temperature, EtCO2, EtSevo or anesthetic protocol. MAP was higher in DEX compared to SAL at 10 (104 ± 27 and 83 ± 23, respectively) and 15 (108 ± 28 and 86 ± 22, respectively) min after treatment. DEX had significantly lower VAS [0.88 (1.13)] and NRS [2.0 (1.5)] scores when compared to SAL [VAS = 1.56 (2.59); NRS = 2.5 (3.5)]. Time to extubation (min) was longer for DEX (19.7 ± 11) when compared to SAL (13.4 ± 10). Prophylactic dexmedetomidine improves recovery quality during the extubation period, but prolongs its duration, in sevoflurane-anesthetized healthy dogs administered fentanyl.

Phase Lag Entropy as a Surrogate Measurement of Hypnotic Depth during Sevoflurane Anesthesia.

Background and Objectives: Phase lag entropy, an electroencephalographic monitor, evaluates the variety in temporal patterns of phase relationship between frontal and prefrontal brain region. Phase lag entropy can reflect the depth of anesthesia induced by propofol, but the association between sevoflurane and phase lag entropy has not been elucidated. This study examined the effect of sevoflurane on phase lag entropy during induction of general anesthesia. We also explored the pharmacodynamic model between end-tidal anesthetic concentration and electroencephalographic monitor. Materials and Methods: A total of 20 patients were enrolled. General anesthesia was produced by escalating the sevoflurane (1 vol% up to 8 vol%). The relationship between phase lag entropy and end-tidal anesthetic concentration was analyzed. A non-linear mixed-effects model was used to get the relationship of pharmacodynamics between the end-tidal sevoflurane concentration and phase lag entropy. Mean blood pressure, heart rate, and the modified observer’s assessment of alertness/sedation scale were also recorded during sevoflurane anesthesia. Results: As level of sedation increased, phase lag entropy decreased. A significant correlation was showed between phase lag entropy and end-tidal sevoflurane concentration (r = −0.759, p < 0.001). The correlation coefficient between the modified observer’s assessment of alertness/sedation scale and phase lag entropy was 0.731 (p < 0.001). The pharmacodynamic factors assessed by the sigmoid Emax model were E0 = 84.9, Emax = 42, Ce50 = 1.81, γ = 4.78, and ke0 = 0.692. The prediction probability of phase-lag entropy for measuring the modified observer’s assessment of alertness/sedation scale and end-tidal sevoflurane concentration were 0.764 and 0.789, respectively. With the increasing concentration of sevoflurane, mean blood pressure decreased, but heart rate did not change. Conclusions: The continuing escalation in end-tidal sevoflurane concentration caused a decline in phase lag entropy. Phase lag entropy can serve as an indicator of hypnotic depth in patients receiving sevoflurane anesthesia.

Effects of sevoflurane anesthesia and abdominal surgery on the systemic metabolome: a prospective observational study

BackgroundMetabolic status can be impacted by general anesthesia and surgery. However, the exact effects of general anesthesia and surgery on systemic metabolome remain unclear, which might contribute to postoperative outcomes.MethodsFive hundred patients who underwent abdominal surgery were included. General anesthesia was mainly maintained with sevoflurane. The end-tidal sevoflurane concentration (ETsevo) was adjusted to maintain BIS (Bispectral index) value between 40 and 60. The mean ETsevo from 20 min after endotracheal intubation to 2 h after the beginning of surgery was calculated for each patient. The patients were further divided into low ETsevo group (mean − SD) and high ETsevo group (mean + SD) to investigate the possible metabolic changes relevant to the amount of sevoflurane exposure.ResultsThe mean ETsevo of the 500 patients was 1.60% ± 0.34%. Patients with low ETsevo (n = 55) and high ETsevo (n = 59) were selected for metabolomic analysis (1.06% ± 0.13% vs. 2.17% ± 0.16%, P < 0.001). Sevoflurane and abdominal surgery disturbed the tricarboxylic acid cycle as identified by increased citrate and cis-aconitate levels and impacted glycometabolism as identified by increased sucrose and D-glucose levels in these 114 patients. Glutamate metabolism was also impacted by sevoflurane and abdominal surgery in all the patients. In the patients with high ETsevo, levels of L-glutamine, pyroglutamic acid, sphinganine and L-selenocysteine after sevoflurane anesthesia and abdominal surgery were significantly higher than those of the patients with low ETsevo, suggesting that these metabolic changes might be relevant to the amount of sevoflurane exposure.ConclusionsSevoflurane anesthesia and abdominal surgery can impact principal metabolic pathways in clinical patients including tricarboxylic acid cycle, glycometabolism and glutamate metabolism. This study may provide a resource data for future studies about metabolism relevant to general anaesthesia and surgeries.Trial registrationwww.chictr.org.cn. identifier: ChiCTR1800014327.

Postoperative recovery of patients with differential requirements for sevoflurane after abdominal surgery: A prospective observational clinical study.

An association between animals and volatile anaesthetic requirements has been shown; however, evidence related to the postoperative outcome of human patients is lacking. Our aim was to investigate whether there is a difference in the requirement for sevoflurane among people undergoing gastrointestinal surgery.We observed 390 adult patients who underwent gastrointestinal surgery with an American Society of Anesthesiologists physical status of I or II with an expected surgery duration of > 2 hours. We used the bispectral index (BIS) to guide the regulation of end-tidal sevoflurane concentration (ETsevo). The mean ETsevo from 20 minutes after endotracheal intubation to 2 hours after the start of surgery was calculated for all patients. Differential sevoflurane requirements were identified according to ETsevo. The BIS, ETsevo, heart rate, mean arterial pressure, dose of sufentanil and cisatracurium, tracheal extubation time, incidence of intraoperative awareness, and incidence of postoperative nausea and vomiting were compared between patients with a low requirement for sevoflurane (group L) and patients with a high requirement for sevoflurane (group H).The mean ETsevo of the 390 patients was 1.55% ± 0.26%. Based on our definition, patients with an ETsevo of < 1.29% were allocated to the low requirement group (group L; n = 69), while patients with an ETsevo of > 1.81% were allocated to the high requirement group (group H; n = 78). The ETsevo of group L was significantly lower than the ETsevo of group H (1.29% ± 0.014% vs 1.82% ± 0.017%, P < .001). There was no significant difference in the ETsevo, BIS, heart rate, mean arterial pressure, dose of sufentanil and cisatracurium, tracheal extubation time, incidence of intraoperative awareness, and incidence of postoperative nausea and vomiting. The tracheal extubation time in the L group was significantly shorter than that in the H group. No intraoperative awareness occurred.There was a significant difference in the requirement for sevoflurane in adult patients. The tracheal extubation time in group L was significantly shorter than that in group H.

Correlation between pain rating index and end-tidal sevoflurane concentration during sevoflurane anesthesia.

ObjectiveTo investigate the correlation between the pain rating index (PRi), which is an index derived from processed electroencephalography signals, and the end-tidal sevoflurane concentration (ETsevo).MethodsThis study involved 50 adults with a body mass index of 18 to 25 kg/m2 who were undergoing elective surgery under general anesthesia. Thyrocricocentesis was performed with 2.5 mL of 2% tetracaine for endotracheal surface anesthesia, and intravenous injections of midazolam, etomidate, and rocuronium were then administered. The patients’ tracheas were intubated and their ventilatory rate was adjusted to maintain the partial pressure of end-tidal carbon dioxide at 30 to 35 mmHg. Anesthesia was maintained with sevoflurane. The ETsevo was adjusted to maintain anesthesia at 0.6, 0.8, 1.0, and 1.2 minimum alveolar concentration for 15 minutes each, and the PRi, mean arterial pressure (MAP), and heart rate were recorded at each concentration.ResultsA negative correlation was found between the PRi and ETsevo (−0.882) and between the MAP and ETsevo (−0.571). A low positive correlation was found between the PRi and MAP (0.484).ConclusionsThe PRi showed a high negative correlation with the ETsevo. Therefore, the PRi can be used to guide the depth regulation of sevoflurane anesthesia.Clinical trial registration number: ChiCTR-IPR-17012092

Effect of Permissive Mild Hypercapnia on Cerebral Vasoreactivity in Infants: A Randomized Controlled Crossover Trial.

Mechanical ventilation interferes with cerebral perfusion via changes in intrathoracic pressure and/or as a consequence of alterations in CO2. Cerebral vascular vasoreactivity is dependent on CO2, and hypocapnia can potentially lead to vasoconstriction and subsequent decrease in cerebral blood flow. Thus, we aimed at characterizing whether protective ventilation with mild permissive hypercapnia improves cerebral perfusion in infants. Following ethical approval and parental consent, 19 infants were included in this crossover study and randomly assigned to 2 groups for which the initial ventilation parameters were set to achieve an end-tidal carbon dioxide (Etco2) of 6.5 kPa (group H: mild hypercapnia, n = 8) or 5.5 kPa (group N: normocapnia, n = 11). The threshold was then reversed before going back to the initial set value of normo- or hypercapnia. At each step, hemodynamic, respiratory, and near-infrared spectroscopy (NIRS)-derived parameters, including tissue oxygenation index (TOI) and tissue hemoglobin index (THI), concentration of deoxygenated hemoglobin (HHb) and oxygenated hemoglobin (O2Hb), were collected. Concomitantly, sevoflurane maintenance concentration, ventilatory (driving pressure) and hemodynamic parameters, as mean arterial pressure (MAP), were recorded. Targeting an Etco2 of 5.5 kPa resulted in significantly higher mean driving pressure than an Etco2 of 6.5 kPa (P < .01) with no difference between the groups in end-tidal sevoflurane, MAP, and heart rate. A large scatter was observed in NIRS-derived parameters, with no evidence for difference in Etco2 changes between or within groups. A mild decrease with time was observed in THI and MAP in infants randomly assigned to group N (P < .036 and P < .017, respectively). When pooling all groups together, a significant correlation was found between the changes in MAP and TOI (r = 0.481, P < .001). Allowing permissive mild hypercapnia during mechanical ventilation of infants led to lower driving pressure and comparable hemodynamic, respiratory, and cerebral oxygenation parameters than during normocapnia. Whereas a large scatter in NIRS-derived parameters was observed at all levels of Etco2, the correlation between TOI and MAP suggests that arterial pressure is an important component of cerebral oxygenation at mild hypercapnia.

A pharmacodynamic model of tidal volume and inspiratory sevoflurane concentration in children during spontaneous breathing.

High concentrations of sevoflurane causes respiratory depression, mainly due to the decrease in tidal volume (TV) during spontaneous ventilation. The purpose of this study was to identify clinical variables that affect the relationship between TV and sevoflurane concentration, and to establish a population pharmacodynamic modelling approach to TV and sevoflurane concentration in children. A prospective observational study involving 48 patients (≤ 6 years of age) scheduled to undergo general anesthesia using laryngeal mask airway was performed. When the inspiratory sevoflurane concentration reached 2 vol%, the vaporizer was increased to 4 vol% for 5 min, then sevoflurane was decreased to 2 vol% for 5 min. During the study period, TV, end-tidal carbon dioxide, and sevoflurane concentration were recorded every 30 s. Pharmacodynamic analysis using a sigmoid Emax model was performed to assess the TV-sevoflurane concentration relationship. To collapse hysteresis of the pharmacokinetic and pharmacodynamic relationship, the semicompartmental model was applied which does not require a structural model for equilibration delay causing the hysteresis. TV decreased with increasing inspiratory sevoflurane concentrations. Hysteresis between the TV and sevoflurane concentration was observed and was accounted for when the model was developed. Initial TV and maximal reduction in TV were related to body weight. The γ (a steepness of the concentration-response relation curve) was 8.78 and the keo, (a first-order rate constant determining the equilibrium between the end-tidal sevoflurane concentration and effect site sevoflurane concentration) was 2.27 min-1. Changes in TV were correlated with sevoflurane concentration with spontaneous breathing during sevoflurane anesthesia. The initial and maximal TV were related to body weight, in a pediatric population.