End-tidal Desflurane Research Articles

Effect of Change of Position (Supine vs. Steep Trendelenburg) on Bispectral Index Value During Robotic Surgery.

Background: Bispectral Index (BIS) is used to monitor anesthetic depth and is a useful instrument to keep a check on intraoperative awareness. But there are various situations in which it shows false readings. Our aim of the study was to observe the changes in BIS value with steep Trendelenburg position, which is usually done, in robotic pelvic surgeries.Methods: We included 100 patients in our study who underwent robotic prostatectomies and hysterectomies. After anesthetizing the patient, the patient's heart rate, systolic blood pressure, mean arterial pressure, end-tidal desflurane, end-tidal CO2, and BISwere recorded at three min. intervals, for 15 minutes before and 15 minutes after the Trendelenburg position without surgical stimulus.Results: We found a significant increase in BIS values (p <0.05) after the change of position from supine to steep Trendelenburg. Heart rate, systolic blood pressure, and mean arterial pressure were almost constant.Conclusion: Our study concluded that the BIS value increases when patients were shifted from the supine to Trendelenburg position, which might raise the concern of a decrease in anesthetic depth.

Influence of hemorrhage and subsequent fluid resuscitation on transcranial motor-evoked potentials under desflurane anesthesia in a swine model.

Hemorrhage increases the effect of propofol and could contribute to false-positive transcranial motor-evoked potential (TcMEP) responses under total intravenous anesthesia (TIVA). We investigated the influence of hemorrhage and subsequent fluid resuscitation on TcMEPs under desflurane anesthesia. Sixteen swine (25.4 ± 0.4kg) were anesthetized with a 4% end-tidal desflurane concentration (EtDes), which was incrementally increased to 6%, 8%, and 10% and then returned to 4% every 15min. This procedure was repeated twice (baseline). After baseline measurements, animals were allocated to either the hemorrhage (n = 12) or control (n = 4) group. In the hemorrhage group, 600ml of blood was removed and the EtDes protocol described above was applied. Hypovolemia was resuscitated using 600ml of hydroxyethyl starch and the EtDes protocol was applied again. TcMEPs were measured at each EtDes. In the control group, measurements were performed without hemorrhage or fluid infusion. TcMEP responses were observed in all conditions in all limbs with 4% EtDes (0.4 MAC). TcMEP amplitudes decreased according to the EtDes to a greater degree in the lower limbs compared with the upper limbs. Hemorrhage enhanced the effect of desflurane on TcMEP amplitudes, and decreased TcMEP by 41 ± 12% in upper limbs and 63 ± 17% in lower limbs compared with baseline. Subsequent fluid resuscitation did not reverse TcMEP amplitudes. TcMEP amplitudes decrease during hemorrhage under desflurane anesthesia. This phenomenon might result from an enhanced effect of desflurane on the spinal motor pathway without increasing the desflurane concentration.

Use of Remifentanil for Open in utero Fetal Myelomeningocele Repair Maintains Uterine Relaxation with Reduced Volatile Anesthetic Concentration

Introduction: Open fetal repair of myelomeningocele (MMC) is an option for prenatally diagnosed spina bifida. Historically, high-dose volatile anesthetic was used for uterine relaxation but is associated with fetal cardiovascular depression. We examined the impact of administering a supplemental remifentanil infusion on the concentration of inhaled anesthetic required for intraoperative uterine relaxation. Methods: We retrospectively analyzed 22 consecutive patients who underwent open fetal MMC repair with desflurane anesthesia from 2014 to 2018. The anesthetic protocol was modified to include high-dose opioid with remifentanil in 2016. We examined intraoperative end-tidal desflurane concentrations, vasopressor use, incidence of umbilical artery Doppler abnormalities, and incidence of preterm labor and delivery. Results: Patients (n = 11) who received desflurane and remifentanil (Des/Remi) were compared to patients (n = 11) who received desflurane (Des) alone. Intraoperatively, the maximum end-tidal desflurane required to maintain uterine relaxation was lower in the Des/Remi group (7.9 ± 2.2% vs. 13.1 ± 1.2%, p < 0.001). The mean phenylephrine infusion rate was also lower in the Des/Remi group (36 ± 14 vs. 53 ± 10 mcg/min, p = 0.004). Discussion: Use of opioid with supplemental remifentanil was associated with lower volatile anesthetic dosing and decreased vasopressor use; fetal outcomes were not different. Remifentanil may allow for less volatile anesthetic use while maintaining adequate uterine relaxation.

Comparative Study of Automated End Tidal Control Versus Manual Fresh Gas Flow Adjustment with Respect to Gas Usage and Delivery during Low Flow Anesthesia

Background: During low-flow manually-controlled anesthesia (MCA) the anesthetist keeps adjusting end-tidal oxygen (EtO2) and anesthetic concentrations (EtAA) constantly to ensure adequate and safe anesthesia. This study was performed to compare End Tidal Control and Manual Control of Fresh gas flow during low flow anesthesia. Methods: Study was conducted on 84 ASA I and II patients 18-65 years age, of either sex, requiring general anesthesia for more than 2 hours. In MCA group (n = 42) target end-tidal desflurane (4%) and EtO2 concentrations (≥ 35%) were manually controlled by the anesthetist. In EtCA group (n = 42), same anesthetic machine with additional end-tidal control feature was used to reach same targets. Results: The median desflurane consumption was 15.71 ml and 16.71 ml in ETCA and MCA respectively (p value =0.002) after one hour and 28.71ml and 32.98 ml in ETCA and MCA respectively (p value <0.001 ) after two hours. In ETCA group, median number of adjustments was 3.83 after one hour and 7 after two hours (p – value <0.001). Cost of anesthetic agent consumed after one hour in ETCA group was Rs 562.57 and MCA group was Rs 598.37 (p value<0.002) . After two hours, cost of anesthetic agent consumed in ETCA group was Rs 1008.367 and in MCA group was Rs 1173.729 (p value <0.001). Conclusion: Automatic implementation of low flow anesthesia using end tidal control is a good system for conserving the consumption of gases and reducing the number of adjustments needed to maintain depth of anesthesia.

Comparison of bispectral index targeted end-tidal concentration of desflurane during three phases of orthotopic liver transplantation.

Background and Aims:Reduced inhalational anaesthetic requirement in end-stage liver disease during living donor orthotopic liver transplantation (LD-OLT) is due to increased endogenous opioids. This study evaluated the changes in bi-spectral index (BIS) monitored end-tidal desflurane (ETDes) requirements during ‘dissection’, ‘anhepatic’, and ‘neohepatic’ phases of LD-OLT.Methods:This prospective, cohort study included 40 adults undergoing LD-OLT under general anaesthesia (GA). All patients received BIS-guided desflurane GA. ETDes requirements in three phases of LD-OLT (primary objective); relationship between inhalational anaesthetic requirements and severity of liver disease; and effect of changes in mean arterial pressure (MAP) and body temperature on ETDes concentration for all three phases were also evaluated.Results:ETDes during the ‘dissection’ phase (2.92 ± 0.65%) was > ‘anhepatic’ (2.68 ± 0.85%, P = 0.049) and ‘neohepatic’ phases (2.58 ± 0.71%, P = 0.005). Patients with model of end-stage liver disease (MELD) score < 20 returned significantly greater ETDes than those with MELD score ≥20 during the ‘dissection’ (MELD <20: 3.11 ± 0.49%; MELD ≥20: 2.58 ± 0.77%, P = 0.01) and ‘anhepatic’(MELD <20: 2.96 ± 0.76%; MELD ≥20: 2.17 ± 0.79%, P = 0.003) phases. A positive correlation was observed between ETDes(r = 0.584, P = 0.001) and temperature in the ‘dissection’ phase only.Conclusion:In patients undergoing LD-OLT, BIS monitoring guidance of depth of desflurane GA suggests lower desflurane requirements during ‘anhepatic’ and the ‘neohepatic’ phase of surgery. Also, the desflurane requirement is greater in patients with lesser severity of liver disease.

Minimal flow anesthesia can be initiated early with the use of higher fresh gas flow to facilitate desflurane "Wash-in".

Background and Aims:More than 80% of delivered anesthetic gases get wasted at high fresh gas flows as they are vented out unused. Use of minimal flow anesthesia is associated with less waste anesthetic gas emission and environmental pollution. There is no approved or validated technique to initiate minimal flow anesthesia and simultaneously achieve denitrogenation of the breathing circuit. We studied the wash-in characteristics of desflurane, when delivered with 50% nitrous oxide, to reach a target end-tidal concentration at two different gas flow rates.Material and Methods:Patients were allocated randomly to two groups of 25 adults each. In Group A, with the vaporizer dial fixed at 4 vol %, after an initial fresh gas flow of 4 L/min was administered to wash-in of desflurane using the closed-circuit, with 50% N2O in O2, and in group B, 6 L/min was used. Minimal flow anesthesia, with 0.5 L/min, was initiated in both groups on attaining a target end-tidal desflurane concentration of 3.5 vol %. After initiation of desflurane delivery, the inspired/expired gas concentrations were noted every minute for 15 min.Results:In Group A, the target desflurane end-tidal concentration was reached in 499.2 ± 68.6 s±, and in the Group B (P < 0.001), it was reached significantly faster in 314.4 ± 69.89 s. Denitrogenation of the circuit was adequate in both groups.Conclusion:Minimal flow anesthesia can be initiated, without any gas-volume deficit, in about 5 min with an initial fresh gas flow rate of 6 L/min and the vaporizer set at 4 vol%.

Low-flow anaesthesia with a fixed fresh gas flow rate.

During the wash-in period in low flow anaesthesia (LFA), high fresh gas flow is used to achieve the desired agent concentration. In this study, we aimed to evaluate the safety of fixed 1L/min fresh gas flow desflurane anaesthesia in both the wash-in and maintenance periods in patients including the obese ones. 104 patients undergoing surgery under general anaesthesia were included. After endotracheal intubation, fresh gas flow was reduced to 1L/min and the desflurane vaporizer was set at 18%. The time from opening the vaporizer to end-tidal desflurane concentration reaching 0.7 MAC was recorded (MAC 0.7 time). Throughout the surgery, hemodynamic variables, FIO2, MAC and BIS values were observed. MAC 0.7 time, BIS and MAC values at the start of surgery, number of adjustments in vaporizer settings, desflurane consumption were recorded. The average MAC 0.7 time was 2.9 ± 0.5min. MAC and BIS values at the start of the surgery were 0.7 (0.6-0.8) and 39 ± 8.5 respectively. No individual patient had a BIS value above 60 throughout the surgery. Hemodynamic variables were stable and FIO2 did not fall below 30% in any patient. The number of adjustments in vaporizer settings was 56. Average desflurane consumption was 0.33 ± 0.05mL/min. We demonstrated that LFA without use of initial high fresh gas flow during the wash-in period is an effective, safe and economic method which is easy to perform.

Efficacy of dexmedetomidine for prevention of emergence agitation in patients posted for nasal surgery under desflurane anaesthesia: A prospective double-blinded randomised controlled trial.

Background and Aims:Nasal surgery under desflurane anaesthesia is more prone to develop emergence agitation (EA). The present study aimed to evaluate the efficacy of dexmedetomidine for prevention of EA.Methods:A total of 72 patients were randomised to group C and group D. Group C patients received placebo while group D patients received dexmedetomidine 1.0 μg/kg bolus followed by 0.4 μg/kg/h after induction of anesthesia. End tidal desflurane was adjusted to keep the bispectral index (BIS) 45–55. Study drug was stopped at extubation. EA was evaluated from extubation till the patient was shifted to postanaesthesia care unit (PACU). Primary outcome was incidence of EA. Secondary outcome measures were requirement of desflurane, haemodynamic stability, and recovery after anaesthesia. The results were analyzed using SPSS version 21.Results:Infusion of dexmedetomidine significantly reduced the incidence of EA (Group C 52.8%; Group D 5.6%) by 89.5% (P = 0.00001). The endtidal desflurane concentration was significantly lower and there was an average 28.87% reduction in requirement of desflurane in group D compared to group C (P < 0.001). The mean heart rate was significantly higher in Group C (P < 0.001). In group C time to extubation, time to achieve BIS 90 and time to response on verbal command was significantly lesser compared to group D (P < 0.0001).Conclusion:Dexmedetomidine significantly reduced the incidence of EA and requirement of desflurane in patients undergoing nasal surgery. However, it was associated with delayed extubation, residual sedation, and prolonged PACU stay.

Advantages of 1-1-12 Wash in Scheme during Induction with Low Flow Anesthesia with and without Nitrous Oxide.

Introduction:In the past, many wash-in schemes have been used with initially high fresh gas flow (FGF) to achieve the necessary alveolar concentration of inhalational agent in 10–15 min. This study was designed to show whether 1-1-12 wash-in scheme proposes an earlier achievement of induction or is there any requirement of high FGF phase to know the time taken for induction with and without nitrous oxide (N2O).Aims:The aim of the study was to find out the time required for the alveolar concentration of desflurane to be from 1% to 6% with and without N2O.Design:It was a potential randomized study which was conducted on sixty patients admitted for elective surgery.Materials and Methods:Two groups of thirty patients each were made and randomly assigned. Group N received desflurane with N2O plus oxygen and Group A received desflurane with air plus oxygen.Statistical Analysis:The observations were noted and evaluated accordingly. Analysis was done using unpaired t-test.Results:Hemodynamic parameters were almost similar in both the groups. In Group N, gradual FAD (Alveolar Desflurane concentration, i.e., end-tidal desflurane) from 1% to 6% was achieved at 0.5, 1, 1.5, 2, 3, and 4 min. In Group A, the same was achieved at 0.6, 1, 1.5, 2, 3, and 4 min (P > 0.05). No significant difference was found between the recuperation time and score in both the groups. Rather complications were more in Group N and statistically significant for nausea and vomiting.Conclusion:Time taken to attain FAD from 1% to 6% was 4 min in both the groups. It is concluded that the recitation of 1-1-12 wash-in scheme is autonomous on the use of N2O and high FGF phase.

Comparison of bispectral index and end-tidal anaesthetic concentration monitoring on recovery profile of desflurane in patients undergoing lumbar spine surgery

Background and Aims:Several techniques have evolved over time to monitor depth of anesthesia and ensure enhanced recovery. This randomized double-blinded trial was designed to compare bispectral index (BIS) or end-tidal anaesthetic concentration (ETAC) monitoring on the recovery characteristics of patients undergoing thoracolumbar spine surgeries.Methods:Seventy American Society of Anesthesiologist I–II patients of either sex were randomized to Group B – BIS-guided protocol, Group E – ETAC-guided protocol, or Group S – Standard protocol. After intravenous induction, anaesthesia was maintained with desflurane in O2/N2O (50:50) mixture. In BIS, ETAC and Standard groups, inspired end-tidal desflurane concentration was varied to achieve BIS of 45–55, 0.8–1.0 age-corrected minimum alveolar concentration, and haemodynamic parameters within 20% of the baseline, respectively. Time to eye opening (emergence time, the primary outcome), time to extubation, and time to name recall from the discontinuation of the anaesthetic agent were recorded. Incidence of nausea, vomiting, and total analgesic consumption was noted for 24 h.Results:Emergence time (mean ± SD) in ETAC (5.1 ± 1.53 min) and BIS (5.0 ± 2.12 min)-guided groups was significantly lower than Standard group (7.5 ± 2.90 min). Extubation time in ETAC (6.3 ± 2.22 min) and BIS-guided group (6.5 ± 1.78 min) was significantly lower than Standard group (9.0 ± 3.20 min) (P < 0.001). Time to achieve fast track score of more than 12 was significantly less in BIS-guided group (13.12 ± 2.59 min).Conclusion:ETAC-guided anaesthesia is comparable to BIS-guided anaesthesia in achieving early recovery.

The effect of nicardipine on the surgical pleth index during thyroidectomy under general anesthesia: A prospective double-blind randomized controlled trial.

Background:The effectiveness of surgical pleth index (SPI) for managing nociception-antinociception balance during general anesthesia with vasodilators, including nicardipine has not been demonstrated. We aimed to compare the time course during surgery in SPI values in patients receiving nicardipine or remifentanil infusion during thyroidectomy.Methods:Forty patients undergoing thyroidectomy were randomly assigned to receive nicardipine (group N; n = 19) or remifentanil (group R; n = 21) along with induction (propofol, fentanyl, and rocuronium) and maintenance (50% desflurane/nitrous oxide in oxygen) anesthesia (goal bispectral index [BIS] ∼50). The infusion of nicardipine or remifentanil was started before the 1st incision and adjusted to keep mean blood pressure (MBP) within ±20% of the preoperative value. SPI, BIS, end-tidal desflurane concentration (EtDes), MBP, and heart rate were recorded at 2.5 minute intervals from the 1st incision to the end of surgery. Extubation and recovery times, pain score/rescue ketorolac consumption, and adverse events in postanesthesia care unit (PACU) were recorded.Results:The trend of SPI during surgery was comparable between the 2 groups (P = 0.804), although the heart rates in group N were significantly higher than those in group R (P = 0.040). The patient characteristics, trends of BIS, EtDes, and MBP during surgery, extubation and recovery times, and incidence of nausea/vomiting were comparable between the groups. Group N had significantly lower pain scores and rescue ketorolac consumption at PACU.Conclusion:SPI was comparable between patients receiving nicardipine or remifentanil infusion during thyroidectomy under general anesthesia, which suggests that the administration of nicardipine may confound the interpretation of SPI values during general anesthesia.Clinical trial registration:This trial was registered in the UMIN clinical trials registry (unique trial number: UMIN000019058; registration number: R000022028; principal investigator's name: Young Ju Won; date of registration: September 17, 2015).

The concentration of desflurane preventing spectral entropy change during surgical stimulation: A prospective randomized trial

Study objectiveTo determine the concentration of desflurane necessary to blunt changes in spectral entropy during surgical incision when two different target-controlled effect-site concentrations of remifentanil (1 and 3ng/ml) were infused. DesignProspective, randomized controlled study. SettingOperating room of a university hospital. InterventionsForty-two patients undergoing general anesthesia for elective surgery were enrolled and randomly allocated to the R1 (1ng/ml of remifentanil, n=21) or R3 (3ng/ml of remifentanil, n=21) group. After at least a 10-min administration of target-controlled remifentanil concentration and predetermined end-tidal desflurane following endotracheal intubation, changes in spectral entropy in response to surgical incision were evaluated. MeasurementsConcentration of desflurane necessary to blunt changes in spectral entropy during surgical incision for each group was determined using Dixon's up-and-down method. Hemodynamic variables including mean arterial pressure (MAP) and heart rate (HR) were measured. Main resultsConcentration of desflurane necessary to blunt changes in spectral entropy during surgical incision in 50% of patients (EC50) was 4.1% (95% CI: 3.5–4.7%) for the R1 group and 3.4% (95% CI: 3.0–3.8%) for the R3 group (P=0.033). Additionally, the calculated EC95 values using the logistic regression analysis for the R1 and R3 groups were 5.8% (95% CI: 5.0–10.8%) and 5.1% (95% CI: 4.3–10.6%), respectively. MAPs and HRs were significantly higher in the R1 than in the R3 group after surgical incision. ConclusionsDesflurane 4.1% with remifentanil 1ng/ml and desflurane 3.4% with remifentanil 3ng/ml significantly blunt the change in spectral entropy after surgical incision in 50% of patients.

Effect of Intravenous Magnesium Sulfate on the Minimum Alveolar Concentrations of Desflurane Using Bispectral Index Monitoring: A Prospective Randomized Double-blind Controlled Study.

Background:Magnesium sulfate has been implicated to influence the minimum alveolar concentration (MAC) of various volatile anesthetics, but its effect on desflurane remains unanswered so far.Aim:To study the effect of perioperative intravenous magnesium sulfate on MAC of desflurane using bispectral index (BIS) monitoring.Settings:Operating room of a tertiary care hospital.Design:A prospective, randomized, controlled, double-blind clinical trial.Methods:Sixty American Society of Anesthesiologists Physical Status I/II patients aged 18–65 years and scheduled for breast conservative surgeries were randomized into three groups of 20 each. Control group (Group 1) was administered 100 ml normal saline (NS) as bolus followed by NS infusion. Magnesium (Mg) was administered as bolus of 40 mg/kg in 100 ml NS followed by NS infusion in Group 2 and as bolus of 40 mg/kg followed by infusion of 10 mg/kg/h of Mg in NS in Group 3. Anesthesia was induced with propofol, fentanyl, and atracurium. Dial setting of desflurane was adjusted to target a BIS of 45–55. Time from cessation of desflurane to beginning of spontaneous movement, time taken to respond to verbal commands, time of extubation, and time taken to reach BIS value of 70 were recorded.Statistical Analysis:Statistics was done using SPSS program using ANOVA and the Chi-square test for variables and a P < 0.05 was taken to indicate a significant difference.Results:No significant difference was present in MAC, end-tidal desflurane, and cumulative consumption of morphine. Recovery was similar in Group 2 and Group 3, but time to eye opening (P = 0.011), time to respond to verbal commands (P < 0.001), and time to extubate (P < 0.001) were significantly delayed when compared with patients in Group 1. Hemodynamic changes were comparable among three groups.Conclusions:From this study, we conclude that MACs of desflurane using BIS as a guide remains unaffected by perioperative infusion of magnesium sulfate.

The effect of perioperative esmolol on early postoperative pain: A systematic review and meta-analysis.

Esmolol has been shown to improve postoperative pain and reduce opioid requirements. The aim of this systematic review was to evaluate the effect of perioperative esmolol as an adjunct on early postoperative pain intensity, recovery profile, and anesthetic requirement. Databases were searched for randomized placebo-controlled trials evaluating the effects of esmolol during general anesthesia. Primary outcomes were related to early postoperative pain whereas secondary outcomes were related to emergence time, postoperative nausea and vomiting, and intraoperative anesthetic requirement. Nineteen trials were identified involving 936 patients (esmolol = 470, placebo = 466). In esmolol group, numeric pain scores at rest in the immediate postoperative period were reduced by 1.16 (95% confidence interval [CI]: 1.97–0.35, I2 = 96.7%) out of 10. Opioid consumption was also decreased in the postanesthesia care unit compared with placebo, mean difference of 5.1 mg (95% CI: 7.0–3.2, I2 = 96.9%) morphine IV equivalents; a 69% reduction in opioid rescue dosing was noted (odds ratio [OR]: 0.31, 95% CI: 0.16–0.80, I2 = 0.0%). A 61% reduction in postoperative nausea and vomiting was also evident (OR: 0.39, 95% CI: 0.20–0.75, I2 = 60.7%). A reduction in propofol induction dose was noted in the esmolol group (mean difference: −0.53 mg/kg, 95% CI: −0.63–−0.44, I2 = 0.0%). A decrease in end-tidal desflurane equivalent (mean difference: 1.70%, 95% CI: −2.39–−1.02, I2 = 92.0%) and intraoperative opioid usage (fentanyl equivalent, mean difference: 440 μg, 95% CI: −637–−244, I2 = 99.6%) was observed in esmolol group. Esmolol had no effect on the emergence time. Perioperative esmolol as an adjunct may reduce postoperative pain intensity, opioid consumption, and postoperative nausea vomiting. Given the heterogeneity, larger clinical trials are warranted to confirm these findings.

End-tidal desflurane concentration for tracheal extubation in adults

Abstract Objective To determine the end-tidal desflurane concentration required for tracheal extubation in anaesthetised adults. Material and methods After hospital Ethics Committee approval, eighteen ASA I–II adult patients (19–65 years of age), who had been scheduled for elective ambulatory surgery were included in the study. Anaesthesia was induced with propofol 2.5 mg / kg, fentanyl 2 μg/kg, and rocuronium 0.6 mg/kg for intubation. Maintenance of anaesthesia was provided by desflurane in oxygen and air (40:60), and remifentanil at 0.05–0.25 μg/kg/min. Neuromuscular function was monitored with train-of-four (TOF) nerve stimulation and acceleromyography. At the end of the surgery neuromuscular blockade was reversed with sugammadex 2–4 mg/kg in accordance with the TOF ratio. The concentration of desflurane at which extubation was attempted was determined by using Dixon's up-and-down method with 0.5% as a step size. Smooth extubation was defined as one without coughing, teeth clenching, gross purposeful movements, and no breath-holding or laryngospasm within 1 min of tracheal extubation. Results It was found that the end-tidal concentration of desflurane was 3.17 ± 0.18% (95% CI: 3–3.35%) for successful extubation in 50% of adults. Conclusion Extubation in patients receiving desflurane may be feasible at 0.62 minimum alveolar concentration.

Concentración al final de la espiración de desflurano requerida para la extubación en el paciente adulto

ObjectiveTo determine the end-tidal desflurane concentration required for tracheal extubation in anaesthetised adults. Material and methodsAfter hospital Ethics Committee approval, eighteen ASA I-II adult patients (19-65 years of age), who had been scheduled for elective ambulatory surgery were included in the study. Anaesthesia was induced with propofol 2.5mg.kg−1, fentanyl 2μg.kg−1, and rocuronium 0.6mg.kg−1 for intubation. Maintenance of anaesthesia was provided by desflurane in oxygen and air (40:60), and remifentanil at 0.05-0.25μg.kg−1.min1. Neuromuscular function was monitored with train-of-four (TOF) nerve stimulation and acceleromyography. At the end of the surgery neuromuscular blockade was reversed with sugammadex 2-4mg.kg−1 in accordance with the TOF ratio. The concentration of desflurane at which extubation was attempted was determined by using Dixon's up-and-down method with 0.5% as a step size. Smooth extubation was defined as one without coughing, teeth clenching, gross purposeful movements, and no breath-holding or laryngospasm within 1min of tracheal extubation. ResultsIt was found that the end-tidal concentration of desflurane was 3.17±0.18% (95% CI: 3%-3.35%) for successful extubation in 50% of adults. ConclusionExtubation in patients receiving desflurane may be feasible at 0.62 minimum alveolar concentration.

Modelling of the Effect of End-Tidal Carbon Dioxide on Cerebral Oxygen Saturation in Beach Chair Position under General Anaesthesia.

Patients undergoing shoulder surgery in the beach chair position (BCP) under general anaesthesia may be at risk of cerebral desaturation. Increasing end-tidal carbon dioxide (EtCO2 ) is the most convenient and powerful method for the management of cerebral desaturation. The purpose of this study was to investigate the quantitative relationship between EtCO2 and cerebral oxygen saturation (rSO2 ) and to identify the associated influencing factors. Fifty-one patients undergoing arthroscopic shoulder surgery in the BCP under general anaesthesia completed this study. Desflurane and remifentanil were used, and EtCO2 was steadily increased and then decreased by adjusting the ventilator settings every 3min. so that time lag of rSO2 response to EtCO2 changes could be delineated. Near-infrared spectroscopy was used to monitor rSO2 response. An indirect response model was used to examine the relationship between EtCO2 and rSO2 . To determine the relevant covariates, a stepwise approach was used. There was a linear relationship between rSO2 and EtCO2 with a slight delay in the peak of rSO2 relative to EtCO2 . Increase in end-tidal desflurane concentration led to a slower response of rSO2 to the changes of EtCO2 (p=0.0002). The presence of diabetes mellitus reduced the reactivity of rSO2 to EtCO2 changes (p<0.0001). This model-based approach revealed that diabetes mellitus attenuates the response of rSO2 to changes in EtCO2 . The management of cerebral desaturation by hypercapnia in patients with diabetes may be less effective than in non-diabetic patients under general anaesthesia with BCP.

Effect of neuromuscular blockade reversal by pyridostigmine on spectral entropy values during recovery from desflurane anesthesia: a prospective, randomized, double-blind, controlled trial.

BackgroundAccording to several studies investigating the relationship between muscle activity and electroencephalogram results, reversal of neuromuscular blockade (NMB) may affect depth of anesthesia indices. Therefore, we investigated the effect of pyridostigmine on these indices via spectral entropy.MethodsFifty-six patients scheduled for thyroidectomy or parotidectomy were included in this study and randomized into two groups. At the start of skin suturing, the desflurane concentration was adjusted to 4.2 vol% in both groups. Following this, the pyridostigmine group (group P, n = 28) was administered pyridostigmine 0.2 mg/kg mixed with glycopyrrolate 0.04 mg/kg, while the control group (group C, n = 28) received normal saline. Entropy values (response entropy [RE] and state entropy [SE]), train of four (TOF) ratio, and end-tidal desflurane concentration were recorded from point of drug administration to 15 minutes post-drug administration.ResultsMean RE values at 15 minutes, when the maximum effect of pyridostigmine was anticipated, showed a statistically significant difference between groups (53.8 ± 10.5 in group P and 48.0 ± 8.8 in group C; P = 0.030). However, mean SE at 15 minutes showed no significant difference between the two groups (P = 0.066). At 15 minutes, there were significant differences in the TOF ratio between the two groups (P < 0.001).ConclusionsNMB reversal by pyridostigmine significantly increased RE values but not SE values. This finding suggests that spectral entropy may be a useful alternative tool for monitoring anesthetic depth during recovery from anesthesia in the presence of electromyogram activity.

Age-dependent decrease in desflurane concentration for maintaining bispectral index below 50.

We examined the hypothesis that the minimum alveolar concentration of desflurane for maintaining bispectral index (BIS) below 50 (MACBIS 50 ) decreases with advance of age. Sixty young (20-30 year), middle-aged (31-65 year) and elderly (66-80 year) patients were included (n = 20, each group). Five minutes following the start of continuous intravenous administration of remifentanil at 0.25 μg/kg/min, general anaesthesia was induced with propofol 2 mg/kg and rocuronium 0.8 mg/kg to facilitate tracheal intubation. Infusion of remifentanil was stopped immediately after tracheal intubation. When BIS began to increase > 60, maintenance of anaesthesia was started with an end-tidal desflurane concentration of 4.0% and maintained for 10 min followed by 1-min assessment of BIS taken at 10-s intervals. MACBIS 50 of each age group was estimated by up-down methodology. MACBIS 50 of desflurane in young, middle-aged and elderly patients was 4.25% end-tidal (95% confidence intervals 4.04-4.46), 3.58% (3.38-3.79) and 2.75% (2.50-3.00) respectively. MACBIS 50 was higher (P = 0.011) in young patients and lower (P = 0.012) in elderly patients than those in middle-aged patients. Advance in age significantly decreased the concentrations of desflurane required to maintain BIS below 50. BIS reflected age-associated decrease in end-tidal concentrations of desflurane required for maintaining adequate depth of anaesthesia during resting state.

The effect of intraoperative dexmedetomidine on postoperative catheter-related bladder discomfort in patients undergoing transurethral bladder tumour resection: A double-blind randomised study.

Catheter-related bladder discomfort (CRBD) due to an indwelling urinary catheter causes postoperative distress. Dexmedetomidine is used as an anaesthetic adjuvant during general anaesthesia and has an antimuscarinic effect, which may be beneficial for the prevention and treatment of CRBD. To determine the effect of intraoperative dexmedetomidine administration on the incidence of CRBD. A double-blind, placebo-controlled, randomised study. A tertiary care teaching hospital. One-hundred and nine patients undergoing transurethral bladder tumour excision (TURB). Patients were randomly allocated to two groups: control group (n = 55) received placebo and dexmedetomidine group (n = 54) received intraoperative dexmedetomidine (1 μg kg(-1) loading dose followed by 0.5 μg kg(-1) h(-1) continuous infusion). The incidence and severity (mild, moderate, severe) of CRBD assessed at 0, 1, 6 and 24 h postoperatively. The incidence of CRBD was significantly higher in the control group at 0 (78 vs. 50%; P = 0.004), 1 (86 vs. 57%; P = 0.002) and 6 h (82 vs. 63%; P = 0.047) postoperatively. The incidence of moderate to severe CRBD was higher in the control group at 0 (38 vs. 11%; P = 0.002) and 1 h (29 vs. 7%; P = 0.006) postoperatively. The number of patients having CRBD treated with tramadol was higher in the control group (24 vs. 12; P = 0.006). The mean end-tidal desflurane concentration during the surgery was higher in the control group (4.5 vs. 3.9%; P = 0.04). The postoperative pain score (numerical rating scale: 0 to 10) was higher in the control group at 0 (4.6 vs. 2.7; P = 0.002), and 1 h (3.8 vs. 2.7; P = 0.041). The number of patients treated with opioids was higher in the control group (21 vs. 8; P = 0.011). Intraoperative dexmedetomidine administration decreased the incidence and severity of early postoperative CRBD as well as intraoperative desflurane and postoperative opioid requirements in patients undergoing TURB. NCT01991223 (www.clinicaltrials.gov).