Concentrations Of Anesthetic Agents Research Articles

End-Tidal Control Versus Manual Control of Inhalational Anesthesia Delivery: A Randomized Controlled Noninferiority Trial.

Precise anesthesia delivery helps ensure amnesia, analgesia, and immobility. Conventionally, the end-tidal anesthetic concentration is maintained through manual adjustment of the fresh gas flow and anesthetic vaporizer output. Some anesthesia delivery systems can deliver and maintain clinician-selected end-tidal anesthetic agent (EtAA) concentration using a modified closed-loop system. We evaluated the performance of an End-tidal Control (EtC) system on the Aisys CS 2 anesthesia machine (GE HealthCare). We hypothesized EtC anesthetic delivery would be noninferior to manually controlled anesthetic delivery. The Multi-site Anesthesia randomized controlled STudy of End-tidal control compared to conventional Results (MASTER) Trial evaluated anesthetic delivery in 210 adult patients receiving inhaled anesthesia. Patients were randomized to either EtC or manual control (MC) anesthetic delivery. The primary objective was to determine whether, compared to conventional anesthesia practice, EtC achieves and maintains clinician-specified EtAA and end-tidal oxygen (Et o2 ) concentrations within defined noninferiority limits. Noninferiority was concluded if the lower limit of the 95% confidence interval (CI) of the difference between the percent duration within the acceptable range (5% of steady state or a margin of ~10% of each agent's minimum alveolar concentration) for EtC and MC was ≥ -5% for both EtAA and Et o2 . Secondary objectives included performance measures: response time: time required to attain 90% of the first desired EtAA, overshoot: amount the controller (or vaporizer delivery) exceeded the desired EtAA, and accuracy: average deviation from the desired EtAA. EtC achieved and sustained targeted EtAA and Et o2 concentrations within the noninferiority threshold. The EtAA was within 5% of the desired value 98% ± 2.05% of the time with EtC compared to 45.7% ± 31.7% of the time with MC (difference 52.3% [95% CI, 45.9%-58.6%], P < .0001). For Et o2 , EtC was within the noninferiority limit 86.3% ± 22.8% of the time compared with MC at 41% ± 33.3% ( P < .0001, difference 45.3% [95% CI, 36.1%-54.5%]). The median response time for achieving 90% of the initial EtAA desired value was 75 seconds with EtC and 158 seconds with MC ( P = .0013). EtC exhibited a median overshoot of 6.64% of the selected EtAA concentration, whereas MC often failed to reach the clinician's desired value. The difference in median percent deviation from desired EtAA value was 15.7% ([95% CI, 13.5%-19.0%], P < 0001). EtC achieves and maintains the EtAA and Et o2 concentration in a manner that is noninferior to manually controlled anesthesia delivery.

A study of the relationship between Bispectral index and age-adjusted minimum alveolar concentration during the maintenance phase of general anesthesia in elective surgery

Abstract Background and Aims: Bispectral index (BIS) and minimum alveolar concentration (MAC) are commonly used to monitor the depth of anesthesia. The objective was to study the correlation between BIS and age-adjusted minimum alveolar concentration (aaMAC) during the maintenance phase of anesthesia. The influence of variables affecting BIS and or aaMAC was studied to determine an equation between BIS and aaMAC. Material and Methods: This prospective observational study was carried out after institutional ethical approval in adult patients 18–60 years of either sex, ASA I and II posted for elective surgery under general anesthesia. Five minutes after airway management, BIS values and aaMAC equivalents were noted during the maintenance phase of anesthesia. aaMAC and corresponding BIS values were recorded every minute for periods, where the anesthetic agent concentration had remained the same during preceding 5 minutes till the switching off of the anesthetic agent. Age, sex, ASA status, use of nitrous oxide, inhalational agent, dose of midazolam, and opioid used were also recorded. Results: BIS/aaMAC showed an inverse correlation. Increasing age, ASA II status, morphine equivalent &gt;5, and use of nitrous oxide, sevoflurane, or isoflurane were associated with a higher BIS at equivalent aaMAC. Using the exchangeable correlation structure, a generalized estimation equation was obtained as the best predictor. Conclusion: Factors affecting both aaMAC and BIS affect the relationship between the two, and although there are wide variations, BIS and aaMAC can be equated and values of either can be calculated if one is known using a generalized estimates equation.

Comparison of automated and manual control methods in minimal flow anesthesia.

New-generation anesthesia machines administer inhalation anesthetics and automatically control the fresh gas flow (FGF) rate. This study compared the administration of minimal flow anesthesia (MFA) using the automatically controlled anesthesia (ACA) module of the Mindray A9 (Shenzhen, China) anesthesia machine versus manual control by an anesthesiologist. We randomly divided 76 patients undergoing gynecological surgery into an ACA group (Group ACA) and a manually controlled anesthesia group (Group MCA). In Group MCA, induction was performed with a mixture of 40-60% O2 and air with a 4L/min FGF until the minimum alveolar concentration (MAC) reached 1. Next, MFA was initiated with 0.5L/min FGF. The target fraction of inspired oxygen (FiO2) value was 35-40%. In Group ACA, the MAC was defined as 1, and the FiO2 was adjusted to 35%. Depth of anesthesia, anesthetic agent (AA) consumption, time to achieve target end-tidal AA concentration, awakening times, and number of ventilator adjustments were analyzed. The two groups showed no statistically significant differences in depth of anesthesia or AA consumption (Group ACA: 19.1 ± 4.9ml; Group MCA: 17.2 ± 4.5; p-value = 0.076). The ACA mode achieved the MAC target of 1 significantly faster (Group ACA: 218 ± 51s; Group MCA: 314 ± 169s). The number of vaporizer adjustments was 15 in the ACA group and 217 in the MCA group. The ACA mode was more advantageous than the MCA mode, reaching target AA concentrations faster and requiring fewer adjustments to achieve a constant depth of anesthesia.

Peri-operative cardiac arrest in children as reported to the 7th National Audit Project of the Royal College of Anaesthetists.

The 7th National Audit Project of the Royal College of Anaesthetists studied peri-operative cardiac arrest. An activity survey estimated UK paediatric anaesthesia annual caseload as 390,000 cases, 14% of the UK total. Paediatric peri-operative cardiac arrests accounted for 104 (12%) reports giving an incidence of 3 in 10,000 anaesthetics (95%CI 2.2-3.3 per 10,000). The incidence of peri-operative cardiac arrest was highest in neonates (27, 26%), infants (36, 35%) and children with congenital heart disease (44, 42%) and most reports were from tertiary centres (88, 85%). Frequent precipitants of cardiac arrest in non-cardiac surgery included: severe hypoxaemia (20, 22%); bradycardia (10, 11%); and major haemorrhage (9, 8%). Cardiac tamponade and isolated severe hypotension featured prominently as causes of cardiac arrest in children undergoing cardiac surgery or cardiological procedures. Themes identified at review included: inappropriate choices and doses of anaesthetic drugs for intravenous induction; bradycardias associated with high concentrations of volatile anaesthetic agent or airway manipulation; use of atropine in the place of adrenaline; and inadequate monitoring. Overall quality of care was judged by the panel to be good in 64 (62%) cases, which compares favourably with adults (371, 52%). The study provides insight into paediatric anaesthetic practice, complications and peri-operative cardiac arrest.

Allergy skin testing with nonirritating concentrations of anesthetic agents

Immediate hypersensitivity reactions to anesthetic agents are rare, but with a worrying morbidity and mortality rate. Allergy evaluation is mandatory when hypersensitivity reactions to anaesthetic agents are suspected. Skin prick tests and intradermal tests are important tools due to their clinical utility in establishing the diagnosis of IgE-mediated hypersensitivity and evaluation of cross-reactivity. This article presents, for informational purposes only, the nonirritating concentrations of general anesthetics and adjuvant agents, neuromuscular blocking agents and agents used in local and regional anesthesia, used in clinical practice for allergy skin testing according to international guidelines. The delayed hypersensitivity adverse reactions can be assessed by patch testing. Concentrations used for such skin testing with topical anesthetic agents from the European baseline series, international comprehensive baseline series and medicament series, are also presented.

An Entropy-Based Prospective Randomized Controlled Trial to Evaluate the Analgesic and Hypnotic Effects of Equipotent Doses of Sevoflurane and Isoflurane in Patients Presenting for Spine Surgeries.

Objectives Minimal alveolar concentration (MAC) of anesthetic agents has been considered a suitable measure of the potency of inhalational anesthetics. Furthermore, it is assumed that equi-MAC concentrations of different anesthetic agents have a similar potency in suppressing responses to painful stimuli. Isoflurane and sevoflurane are two commonly used volatile anesthetic agents in spine surgeries. Therefore, these agents' hypnotic and analgesic potencies should be distinguished and comprehended for the optimal administration of anesthesia. Consequently, we undertook this study to compare the analgesic and hypnotic potencies between these agents at equi-MAC concentrations, using the entropy monitor. Materials and Methods Forty patients undergoing lumbar spine surgery were randomly assigned to two groups receiving either isoflurane ( n = 20) or sevoflurane ( n = 20). After induction, maintenance of anesthesia was done with age-corrected 1.0 MAC of either isoflurane or sevoflurane. A standardized noxious stimulus was provided to all the patients after achieving a steady state of 1.0 MAC. The state entropy (SE), response entropy (RE), and RE–SE were recorded at baseline, prestimulus, and poststimulus time points in both groups. Statistical Analyses Data are presented as frequency and percentages for categorical variables and mean ± standard deviation for continuous variables. The comparison of categorical variables between the two groups was made using the Fisher's exact test, and the Student's t -test was used for continuous variables. A p -value of < 0.05 was considered to be statistically significant. Results At age-corrected 1.0 MAC, there was no significant difference in the SE, RE, and RE–SE in both the groups at any time point. Conclusion Our study shows that during a steady state of age-corrected 1.0 MAC single-agent anesthesia, sevoflurane and isoflurane have comparable analgesic and hypnotic potencies as measured by entropy indices when a standardized nociceptive stimulus is provided.

Propofol context-sensitive decrement times in children.

Plasma drug concentration is the variable linking dose to effect. The decrement time required for plasma concentration of anesthetic agents to decrease by 50% (context-sensitive half-time) correlates with the time taken to regain consciousness. However, the decrement time to consciousness may not be 50%. An effect compartment concentration is associated more closely with return of consciousness than plasma concentration. An alternative decrement time, the time required for propofol to decrease to a predetermined effect compartment concentration associated with movement (eg, 2µg.ml-1 ), was used to simulate time for the concentration to decrease from steady state at a typical targeted effect compartment concentration 3.5µg.ml-1 in children. These times were short and reflected a decrement time to consciousness (CSTAWAKE ) increase that was small with longer infusion time. CSTAWAKE ranged from 7.5min in 1-year-old infant given propofol for 15min to 13.5min in a 15-year-old adolescent given a 2-hour infusion. Changes in decrement time with age reflect maturation of drug clearance. Neonates had prolonged increment times, 10min after 15min infusion and 18min after 120min infusion using a target concentration of 3.5µg.ml-1 . Decrement times to a targeted arousal concentration are context-sensitive. Use of a higher target concentration of 6µg.ml-1 doubled decrement times. Decrement times are associated with variability: delayed recovery beyond these simulated times is likely more attributable to the use of adjuvant drugs or the child's clinical status. An understanding of propofol decrement times can be used to guide recovery after anesthesia.

General anaesthesia for nonobstetric surgery during pregnancy

Nonobstetric surgery may be required in up to 1% of pregnancies. Most common procedures are urgent abdominal surgeries requiring general anaesthesia. Maintaining normal maternal physiology during anaesthesia is vital. Left lateral tilt position prevents aortocaval compression and preserves normal venous return. Preparation for a difficult airway is required in all obstetric patients due to the known anatomical and physiological changes. Aspiration prophylaxis and a rapid sequence induction are traditionally recommended to avoid the (probably overestimated) risk of aspiration. Although the minimum alveolar concentration (MAC) of volatile anaesthetic agents is reduced by 30 to 40%, awareness occurs more frequently in the obstetric population. Maternal outcomes from surgery are comparable with those of nonpregnant women, but increased incidences of foetal loss, preterm delivery, low birth weight and caesarean section have been reported. Although animal studies have observed impaired foetal brain development after antenatal exposure to anaesthesia, the translational value of these studies remain controversial. Clinical evidence is nearly absent. Withholding urgent/essential procedures is certainly more threatening than proceeding with the surgery. To increase the safety of mother and foetus, nonurgent or nonessential procedures should be postponed until after delivery, and if procedures cannot wait, locoregional anaesthesia should be used if possible. Where general anaesthesia cannot be avoided, the duration of exposure should be kept to a minimum. This narrative review summarises the literature of the past 20 years concerning the anaesthetic management and outcomes of nonobstetric surgery under general anaesthesia during pregnancy.

Determination of the minimum alveolar concentration of isoflurane in donkeys

Introduction: The minimum alveolar concentration (MAC) of volatile anesthetic agents provides important clinical information. The MAC of isoflurane in donkeys is unreported.

Micro-Fuel Cell Sensor-Based Transcutaneous Anesthesia Monitoring Systems (TAMS)

In surgical procedures, it is vital to keep the anesthetic agent concentration appropriate as a slight variation can cause either an overdose or awareness in the surgery. Most of the anesthesia apparatuses in current practice do not have a system for monitoring the anesthetic agent's concentration; therefore, a convenient anesthetic monitor to continuously measure the concentration is highly expected. The widely used inhalational anesthesia, isoflurane (1-chloro-2,2,2-trifluoromethyl difluoromethyl ether) is colorless, volatile, and nonflammable. Therefore to maintain the anasthesia, complex machines equipped with vaporizers and infrared (IR) sensors are used to deliver the required dose of isoflurane. However, existing IR analyzers for the isoflurane have to be operated with highly precise optical alignments, which find limited deployment for critical care in low resource environments due to size, cost, and complexity. Results from controlled or uncontrolled administration of the anesthetic bring serious negative health outcomes. There is an urgent unmet clinical need to cost-effectively ensure the patient's safety and the personnel exposed in the operating room. We are developing a transcutaneous isoflurane biosensor device that can accurately measure volatile anesthetic gas concentration in blood at a much lower cost/unit to address this unmet need. Our approach consists of using micro-fuel cell Transcutaneous Anesthesia Monitoring Systems (TAMS). Micro-fuel cell TAMS is the simplest form of an electrochemical device composed of a Proton Exchange Membrane (PEM) sandwiched between two metal electrodes. In micro-fuel cell TAMS sensing application, an electrical current is directly generated to the isoflurane concentration. Comparing to the existing IR analyzers, micro-fuel cell TIMS is much smaller but more robust. It can be easily deployed for applications under various environmental applications. This easy-to-use, low-cost anesthetic sensing system will provide the patients' safety during surgical procedures, even in low-resource settings in the developing world. We propose the micro-fuel cell TAMS for cost-effectively and continuously accurate anesthesia detection.

Femoral Blokta Farklı İki Doz Bupivakain Protokolünün Postoperatif Analjezi Üzerine Etkisi: Tek Merkez Verilerinin Retrospektif Analizi

INTRODUCTION: In our study, we aimed to compare the analgesic efficacy, side effect profile and its effect on opioid consumption of the femoral nerve block applied with different concentrations of local anesthetic agents (%0.5 bupivacaine and %0.25 bupivacaine) in the same volume (20 mL) after total knee replacement (TKR) operation. METHODS: The files of patients who underwent unilateral TKR surgery under spinal anesthesia between August 2018 and June 2019 were retrospectively reviewed. A total of 163 patients were included in the study, 81 patients in group 1 who received %0.25 bupivacaine, and 82 patients in group 2 who received %0.50 bupivacaine for femoral block. The highest visual analogue pain scale (VAS) scores in the postoperative 24 hours, the amount of tramadol requested and consumed with intravenous patient-controlled analgesia (PCA) devices, and whether there was a significant difference in terms of side effects (nausea, vomiting, motor and sensory deficit) were analyzed. RESULTS: The highest VAS score in group 1 was 2.95 ± 1.31, in group 2 it was 2.84 ± 1.06, and there was no significant difference between them. The mean consumption of tramadol was 197.04 ± 92.03 mg in group 1 and 208.05 ± 85.06 mg in group 2. There was no difference between the demand and consumption of tramadol and side effects. DISCUSSION AND CONCLUSION: 20 mL %0.25 bupivacaine for the femoral block provided the equivalent analgesic efficacy to the same volume of %0.50 bupivacaine. We think that the use of % 0.25 bupivacaine is a more reliable option to reduce systemic side effects, motor block risk and complications.

Minimum Alveolar Concentration of Sevoflurane as a Single Hypnotic Agent to Maintain BIS Below 50 in Patients During Normothermic Cardiopulmonary Bypass

Minimum alveolar concentration (MAC) of volatile anesthetic agents to maintain bispectral index (BIS) below 50 in 50% of patients was defined as MACBIS50. The primary objective of this study was to determine the minimum alveolar concentration of sevoflurane as a single hypnotic agent to maintain BIS below 50 in patients during normothermic cardiopulmonary bypass. Prospective and observational study. Dante Pazzanese Institute of Cardiology, Brazil. Eighteen consecutive patients scheduled for elective coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) under general anesthesia, American Society of Anesthesiologists physical status classes III and IV, between the ages of 40 and 70, were included in the study. All patients underwent inhalation induction with facial mask using sevoflurane (Cristália) in 100% oxygen, pancuronium (Cristália) 0.1 mg/kg, and sufentanil (Cristália) 0.5 µg/kg intravenously (IV) administered. A single bolus dose of sufentanil, 1.0 µg/kg IV, was administered before surgical incision. MACBIS50 was calculated using the midpoint concentration of patients involving a crossover (BIS < or ≥50) according to Dixon's Up-and-Down method. The Up-and-Down sequence also was analyzed by probit test that enabled the authors to obtain the effective dose 50 (ED50) and effective dose 95 (ED95) of sevoflurane to maintain a BIS value <50, with a 95% confidence interval (95% CI) of the mean. A total of 15 patients were analyzed in this study. MACBIS50 of sevoflurane as a single hypnotic agent was 0.82% (95% CI 0.47-1.16) in patients aged 40 to 70 undergoing CABG during normothermic CPB. The ED50 and ED95 of sevoflurane to maintain a BIS value <50 for the same context were 0.73% (95% CI 0.45-1.00) and 1.39 (95% CI 0.42-2.37) by means of probit analysis, respectively. MACBIS50 of sevoflurane as a single hypnotic agent was 0.82% in patients undergoing CABG during normothermic CPB.

The anti-tumoral effects of different local anesthetics on human endometrial carcinoma cell line: An in-vitro study

Background: There is accumulating evidence on the inhibitory effect of local anesthetic agents on metastasis and tumor recurrence on various cancer types. In this study, we aimed to test the effects of lidocaine, bupivicaine and prilocaine on cellular viability and apoptosis on human endometrial adenocarcinoma cell lines (Ishikawa cells). Material and methods: Human Endometrial adenocarcinoma cells (Ishikawa cells) were exposed to different concentrations of local anesthetic agents for 24, 48, and 72 hours. The cell viability assay was performed via MTT and concentrations corresponding to 50% effective concentration (EC50) of cells were determined for each agent. Apoptosis was evaluated via commercial Biocolor ApoPercentage assay. Results: All of the three local anesthetics reduced the amount of viable tumor cells in a dose-dependent manner. The EC50 values (mM) at 24, 48 and 72 h incubation periods were 11.67, 1.915, 2.114 for lidocaine 11.4, 5.21, 3.12 for bupivacaine 7.64 mM, 7.3 mM, and 2.83 mM, for prilocaine respectively. Conclusion: Lidocaine, bupivacaine, and prilocaine have anti-tumoral effects on Ishikawa cell lines. All of the tested agents induced apoptosis and necrosis at high concentrations in a dose dependent-manner.

Interactions among Genetic Background, Anesthetic Agent, and Oxygen Concentration Shape Blunt Traumatic Brain Injury Outcomes in Drosophila melanogaster.

Following traumatic brain injury (TBI), the time window during which secondary injuries develop provides a window for therapeutic interventions. During this time, many TBI victims undergo exposure to hyperoxia and anesthetics. We investigated the effects of genetic background on the interaction of oxygen and volatile general anesthetics with brain pathophysiology after closed-head TBI in the fruit fly Drosophila melanogaster. To test whether sevoflurane shares genetic risk factors for mortality with isoflurane and whether locomotion is affected similarly to mortality, we used a device that generates acceleration–deceleration forces to induce TBI in ten inbred fly lines. After TBI, we exposed flies to hyperoxia alone or in combination with isoflurane or sevoflurane and quantified mortality and locomotion 24 and 48 h after TBI. Modulation of TBI–induced mortality and locomotor impairment by hyperoxia with or without anesthetics varied among fly strains and among combinations of agents. Resistance to increased mortality from hyperoxic isoflurane predicted resistance to increased mortality from hyperoxic sevoflurane but did not predict the degree of locomotion impairment under any condition. These findings are important because they demonstrate that, in the context of TBI, genetic background determines the latent toxic potentials of oxygen and anesthetics.

Are high fresh gas flow rates necessary during the wash-in period in low-flow anesthesia?

In low-flow anesthesia (LFA), there is a wash-in period in which usually high fresh gas flow (FGF) rates are used to achieve the required initial concentration of anesthetic agent in the alveoli. The aim of this study was to compare the efficiency, safety and the consumption of desflurane in LFA using constant FGF (1 L/min) and conventional LFA using high FGF (4 L/min) during the wash-in period. Eighty patients, who were scheduled for elective surgery under general anesthesia with endotracheal intubation, were enrolled in the study. Wash-in was accomplished with 1 L/min FGF (50% O2, 50% air) and 18% desflurane in group 1; and by 4 L/min FGF (50% O2, 50% air) and 6% desflurane in group 2. Throughout the surgery, the vaporizer was adjusted to maintain 0.6 to 0.8 minimum alveolar concentration (MAC). The time required to reach 0.7 MAC was shorter in group 1 (160 seconds [135-181] vs 288 seconds [240-500], P < .001). In 6 patients in group 1 and 13 in group 2, vaporizer settings were adjusted to maintain 0.6 to 0.8 MAC (P = .048). Desflurane consumption in the first hour and total desflurane consumption were higher in group 2 (P < .001 and P = .012, respectively). The efficiency of anesthesia in both the first hour and in total was higher in group 1 (P < .001). It is safe, more efficient, and economical to use 1 L/min FGF during the wash-in period in LFA.

ANESTHETIC EFFICACY OF CLOVE OIL AND 2-PHENOXYETHANOL ON DOCTOR FISH, &lt;i&gt;Garra rufa&lt;/i&gt; (HECKEL, 1843)

This study aimed to determine the anesthetic efficacy of clove oil and 2-phenoxyethanol on doctor fish (Garra rufa) at two different water temperatures. Experimental fish (1.2 ± 0.2 g mean weight) were subjected to 25, 50, 75 and 100 μL L-1 clove oil and 100, 200, 300, 400 and 500 μL L-1 2-phenoxyethanol concentrations at water temperature of 15 and 25 °C, and the induction and recovery times were investigated. Results showed that induction and recovery times in doctor fish were significantly affected by clove oil and 2-phenoxyethanol concentrations as well as water temperature. The interaction of anesthetic concentration and water temperature on all induction stage time was significant in clove oil. Between the anesthetic concentration and temperature interaction was significant for recovery times in both anesthetic agents. The induction time decreased significantly with increasing concentration of both anesthetic agents at water temperature of 15 and 25 °C. The lowest effective concentrations that produced induction within 3 min and recovery within 5 min were 50-75 μL L-1 of clove oil and 300 μL L-1 of 2-phenoxyethanol in both 15 and 25 °C respectively. The results also indicated that clove oil was effective at 4-fold lower concentrationsthan 2-phenoxyethanol, but the recovery time was longer than 2-phenoxyethanol. These results suggest that clove oil and 2-phenoxyethanol were effective anesthetics and could be used as anesthetic agents in doctor fish.

A randomized prospective study comparing characteristics of Desflurane with Isoflurane under low flow anaesthesia using equilibration time

Introduction: Equilibration point of an inhalational agent is the transition point when ratio of expired (Fe) to inspired (Fi) concentration of inhalational anaesthetic agent (Fe/Fi) reaches 0.8 or when uptake of volatile agent reaches 80%. It helps in reducing the duration of initial high gas flows before switching over to low flows. Aim: To compare Desflurane with Isoflurane for equilibration time, intraoperative hemodynamic parameters and post extubation recovery parameters. Materials and Methods: Depending on the volatile anesthetic agent being used patients were randomly allocated into two groups. Group I (n =25) received Desflurane and Group II (n=25) received Isoflurane as inhalational anesthetic agent. In all patients low flow anaesthesia was given after achieving equilibration time and that time was noted. Other parameters measured were intraoperative heart rate, mean blood pressure, mean EtN2O, mean EtFe (End tidal volatile anesthetic agent concentration), recovery parameters (recovery time, recovery score and vitals) and any complications if any. Statistics: Analysis was performed on SPSS (Statistical package for social sciences) version 17.0 Statistical Analysis Software. Result: The equilibration point for group I was achieved in 2.18 ± 0.84 min and for group II was achieved in 10.08 ± 2.36 min and this difference was statistically significant. The intraoperative heart rate and MAP did not differ significantly (p>0.05) between the two groups at all time periods. On comparing, post extubation vitals i.e. HR (8.1%) and recovery time (69.9%) they were found significantly (p Conclusion: Desflurane use results in shorter equilibrium time and earlier reduction of FGF with early and better recovery than Isoflurane. Keywords: Desflurane, Isoflurane, Low flow Anaesthesia, Equilibration time.

General anesthesia influence on cochlear implant intraoperative testing

In this article, we consider the influence of combined general anesthesia on the results of electrically-involved stapedial reflex threshold (esrt) registration. We pay a special attention to the anesthesia to exclude its influence on the esrt. This study included 52 patients with bilateral chronic neurosensory hearing impairment. We conducted a retrospective (from 2014 to 2016) and prospective (from 2017 to 2018) analysis of anesthesia protocols. Even though the inhaled anesthesia (sevoflurane in this case) has a depressive effect on esrt registration (the higher the minimal alveolar concentration of anesthetic agent, the higher the reflex threshold), our study shows a possibility of using it in an extended anesthesia monitoring. Inclusion of myorelaxants in cochlear implantation anesthesia protocol not only provides a safe anesthesia, but also does not prevent a timely intraoperative cochlear implant testing.

End-Tidal Hypocapnia Under Anesthesia Predicts Postoperative Delirium.

Background: Postoperative delirium (POD) might be associated with anesthetic management, but research has focused on choice or dosage of anesthetic drugs. We examined potential contributions of intraoperative ventilatory and hemodynamic management to POD.Methods: This was a sub-study of the ENGAGES-Canada trial (NCT02692300) involving non-cardiac surgery patients enrolled in Winnipeg, Canada. Patients received preoperative psychiatric and cognitive assessments, and intraoperatively underwent high-fidelity data collection of blood pressure, end-tidal respiratory gases and anesthetic agent concentration. POD was assessed by peak and mean POD scores using the Confusion Assessment Method-Severity (CAM-S) tool. Bivariate and multiple linear regression models were constructed controlling for age, psychiatric illness, and cognitive dysfunction in the examination of deviations in intraoperative end-tidal carbon dioxide (areas over (AOC) and under the curve (AUC)) on POD severity scores.Results: A total of 101 subjects [69 (6) years of age] were studied; 89 had comprehensive intraoperative hemodynamic and end-tidal gas measurements (data recorded at 1 Hz). The incidence of POD was 11.9% (12/101). Age, cognitive dysfunction, anxiety, depression, and intraoperative end-tidal CO2 (AUC) were significant correlates of POD severity. In the multiple regression model, cognitive dysfunction and AUC end-tidal CO2 (0.67 kPa below median intra-operative value) were the only independent significant predictors across both POD severity (mean and peak) scores. There was no association between cumulative anesthetic agent exposure and POD.Conclusions: POD was associated with intraoperative ventilatory management, reflected by low end-tidal CO2 concentrations, but not with cumulative anesthetic drug exposure. These findings suggest that maintenance of intraoperative normocapnia might benefit patients at risk of POD.

Estimation of the effect-site equilibration rate constant using the time-to-peak effect of muscle relaxants measured by train-of-four stimulation during general anesthesia induction.

BackgroundThe concept of the effect-site concentration of anesthetic agents is important. The effect compartment model can be explained using the concepts of effect-site concentration and effect-site equilibration rate constant (ke0). This study confirms that the time-to-peak effect (tpe) can be measured easily in clinical practice by applying a priming dose and train-of-four (TOF) during general anesthesia induction, and ke0 can be calculated from the tpe of the four muscle relaxants that are commonly used in general anesthesia.MethodsEighty patients who received general anesthesia were divided into the succinylcholine, rocuronium, atracurium, or vecuronium groups. Priming doses of muscle relaxants were administered. The effects of muscle relaxants were quantified by recording the twitch response of the adductor pollicis muscle after stimulating the ulnar nerve. The tpe was measured at the lowest TOF value. ke0 was calculated from the measured tpe.ResultsThe ke0 values of the succinylcholine, rocuronium, atracurium, and vecuronium groups were 0.076 (0.030)/min, 0.228 (0.122)/min, 0.062 (0.011)/min, and 0.077 (0.019)/min, respectively.ConclusionsIt is possible to estimate ke0 from the tpe of muscle relaxants using a priming dose and TOF during general anesthesia induction.