End-tidal Desflurane Concentration Research Articles

Pharmacokinetics of desflurane uptake and disposition in piglets.

Many respiratory but few arterial blood pharmacokinetics of desflurane uptake and disposition have been investigated. We explored the pharmacokinetic parameters in piglets by comparing inspiratory, end-tidal, arterial blood, and mixed venous blood concentrations of desflurane. Seven piglets were administered inspiratory 6% desflurane by inhalation over 2h, followed by a 2-h disposition phase. Inspiratory and end-tidal concentrations were detected using an infrared analyzer. Femoral arterial blood and pulmonary artery mixed venous blood were sampled to determine desflurane concentrations by gas chromatography at 1, 3, 5, 10, 20, 30, 40, 50, 60, 80, 100, and 120min during each uptake and disposition phase. Respiratory and hemodynamic parameters were measured simultaneously. Body uptake and disposition rates were calculated by multiplying the difference between the arterial and pulmonary artery blood concentrations by the cardiac output. The rates of desflurane body uptake increased considerably in the initial 5min (79.8ml.min-1) and then declined slowly until 120min (27.0ml.min-1). Similar characteristics of washout were noted during the subsequent disposition phase. Concentration-time curves of end-tidal, arterial, and pulmonary artery blood concentrations fitted well to zero-order input and first-order disposition kinetics. Arterial and pulmonary artery blood concentrations were best fitted using a two-compartment model. After 2h, only 21.9% of the desflurane administered had been eliminated from the body. Under a fixed inspiratory concentration, desflurane body uptake in piglets corresponded to constant zero-order infusion, and the 2-h disposition pattern followed first-order kinetics and best fitted to a two-compartment model.

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.

Perseus A500 enables faster recovery from desflurane general anesthesia.

The Dräger Perseus A500 (Perseus) anesthetic workstation has been designed with a lower internal volume. We evaluated the recovery time following general anesthesia using the Perseus workstation compared with that using the conventional Dräger Fabius Plus workstation. Following approval by our institutional research ethics committee, 50 patients receiving elective surgery under general anesthesia were enrolled in the study. Written informed consent was obtained from each patient. The patients were divided into the Perseus group and a control group. The Perseus anesthesia workstation was used for the Perseus group, and the Fabius Plus was used for the control group. General anesthesia was maintained with a 4.2% end-tidal concentration of desflurane, remifentanil, fentanyl, and regional anesthesia. After the surgical procedure, the administration of desflurane was discontinued. The inspiratory and expiratory desflurane concentration, time taken for patients to open their eyes, and the time taken to extubate the trachea after discontinuation of anesthetics were recorded. The inspiratory and expiratory desflurane concentration after the administration of desflurane was discontinued was lower in the Perseus group. Moreover, the time taken for patients to open their eyes was statistically significantly quicker in the Perseus group when compared with the control group: 284 ± 60 vs 325 ± 43s, respectively. The time taken for extubation was also statistically significantly quicker in the Perseus group when compared with the control group: 350 ± 67 vs 388 ± 62s, respectively. We demonstrate in this study that Perseus enables the faster wash-out of anesthetics and faster recovery of patients after general anesthesia.

Comparison of recovery characteristics with two different washout techniques of desflurane anaesthesia: A randomised controlled trial.

Background:Rapid emergence with low soluble inhalational agents (IA) is offset by a significant association with emergence agitation (EA). Research on the influence of elimination methods of IA on recovery characteristics is very few. We conducted this study to compare the recovery characteristics of slow elimination (SE) of desflurane with purging technique.Methodology:Forty-five participants, 18–60 years, undergoing elective laparoscopic surgeries were randomised either into Group-P (n = 23) or Group-SE (n = 22). A standardised induction-maintenance protocol including desflurane and fresh gas flow (FGF) of 0.8 l/min was followed. During recovery, the FGF was increased in Group-P to 10 L/min and in Group-SE it was continued at 0.8 L/min. The decrement in end-tidal concentration of desflurane, time for emergence and extubation, EA and time for psychomotor recovery were noted.Results:Time for emergence (Group-SE: 22.8 ± 9 vs. Group-P: 5.6 ± 1.5 min; P = 0.000) and emergence to extubation duration (Group-SE: 128 ± 36 s vs. Group-P: 11.5 ± 1.7 s; P = 0.000) were longer in the Group-SE than in Group-P. EA occurred in 22.7% patients in Group-SE and in 4.3% patients in Group-P (P = 0.07). Psychomotor recovery to baseline values was seen in more number of patients in Group-SE than Group-P at 30 min. There was no difference between the groups at 60 min post-extubation.Conclusions:Slow elimination using FGF of 0.8 L/min significantly prolongs emergence even with low soluble agent like desflurane. SE is not beneficial in decreasing the incidence of EA or hastening psychomotor recovery. Purging technique is, therefore, a better-suited technique with fewer complications for eliminating desflurane.

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%.

Determination of minimum alveolar concentration and cardiovascular effects of desflurane in positive-pressure ventilated sheep.

OBJECTIVE To determine the minimum alveolar concentration of desflurane (MACDES) and effects on cardiovascular variables in positive-pressure ventilated sheep. ANIMALS 13 adult female sheep. PROCEDURES Anesthesia was induced with desflurane. After a 30-minute equilibration at an end-tidal concentration of desflurane (etDES) of 10.5%, an electrical stimulus (5 Hz/ms and 50 mA) was applied for 1 minute or until gross purposeful movement occurred. The etDES was then changed by 0.5% (modified up-down method), depending on whether a positive motor response had been elicited, and stimulation was repeated. The MACDES was the etDES midway between a positive and negative response. After MACDES was determined, etDES was increased to 1.3 and 1.6 MACDES. Animals were allowed to equilibrate for 15 minutes, and cardiovascular, blood gas, acid-base, and hematologic variables were measured. Times to induction of anesthesia, extubation, attainment of sternal position, and standing and duration of anesthesia were recorded. RESULTS Mean ± SD MACDES was 9.81 ± 0.79%. Times to intubation, extubation, and standing were 4.81 ± 2.21 minutes, 14.09 ± 4.05 minutes, and 32.4 ± 12.5 minutes, respectively. Duration of anesthesia was 226 ± 22 minutes. Heart rate increased significantly at induction of anesthesia but otherwise remained at preanesthetic rates. Arterial blood pressures progressively decreased with increasing etDES; pressures increased slightly only in response to noxious stimulation. CONCLUSIONS AND CLINICAL RELEVANCE The MACDES determined here compared favorably with that determined for other sheep populations and indicated similar anesthetic potency as in other species. Desflurane caused dose-dependent arterial hypotension, which indicated the need for careful blood pressure monitoring.

Desflurane with Isoflurane under low flow anaesthesia: A prospective randomized clinical comparative trial

Aim: To compare characteristics of Desflurane with Isoflurane under low flow anaesthesia using equilibration time. Material and methods: This prospective study was done the Department of AnaesthesiaMetro Hospital and Cancer Research Center, Jabalpur, Madhya Pradesh, India 100 healthy patients of either sex scheduled for routine surgeries, American Society of Anesthesiologists (ASA) physical status I and II, age 20–60 years, and hemoglobin more than 10 g/dL were include in this study. Patients were randomly allocated to two groups. Group I received desflurane as the inhalational anesthetic agent with minimal flow anesthesia (n=50). Group II received isoflurane as anesthetic agent with minimal flow anesthesia (n=50). Results: 100 adult patients were studied. The groups were randomly divided into two groups of 50 patients each. Mean of time taken for equilibration of the volatile anesthetic agent in the desflurane group was 5.23 ± 1.63 min and in the isoflurane group was 17.011±9.64 min, and the difference was statistically significant (P< 0.001). At 5, 20, 60, and 120 min, mean end-tidal concentrations (in kPa) of desflurane were not changed much and were 4.68 ± 0.80, 4.78 ± 0.62, 4.38 ± 0.61 and 4.15 ± 0.62, respectively. In the isoflurane group, variation were significant over time and were 0.77 ± 0.17, 0.93 ± 0.17, 0.73 ± 0.19 and 0.74 ± 0.19 at 5, 20, and 120 min intervals, respectively. Uptake of nitrous oxide was 80% and above by the time equilibration of any of the agents occurred. In both the groups, end-tidal to inspired nitrous oxide ratio was found to be 0.77 ± 0.14 in 5 min duration and 0.96 ± 0.03 by 12 min. Nitrous oxide concentration also fell over the time, and it was difficult to maintain nitrous oxide at 66 vol.% . It ranged between 42.30 ±4.57 and 61.20 ± 4.56. In long duration, minimal flow anesthesia nitrous oxide end-tidal concentration found to be <50%. At 80% uptake point of nitrous oxide, uptake of only desflurane was found to be nearly 80% at that time. Conclusion: we concluded that, with availability of agents like desflurane we can use minimal flow anesthesia more efficiently, with less drift in anesthetic gases and a clear-headed recovery and minimum operating room pollution.

The influence of gradually increasing the concentration of desflurane on cerebral perfusion pressure in rabbit.

In nearly all cases of general anaesthesia with a volatile agent, the anaesthetic concentration has to be increased. Since the anaesthetic affects both the factors determining intracranial homeostasis and the systemic circulation, it is crucial that cerebral perfusion pressure (CPP) is protected. The aim of the present study was to assess the influence of gradually increased concentrations of desflurane on the cerebral and systemic circulations based on CPP, mean arterial pressure (MAP), intracranial pressure (ICP) and their correlations. The study was carried out on 25 rabbits of the same gender (male) randomly assigned to two groups: control (n = 10) and group I (n = 15). Over three 15-minute periods, the animals were exposed to increase concentrations of desflurane so as to achieve 1/3, 2/3 and 1 MAC Minimal Alveolar Concentration (3, 6, 9 vol%) of the effective end-tidal concentration of desflurane (Et) at the end of each period, respectively. Intragroup analysis of CPP changes demonstrated decreases in its successive values from minute 18, compared with baseline values. The mean values of ICP did not differ throughout the experiment. From minute 19 on, all successive values of MAP decreased compared with baseline values. A weak correlation (r = -0.2179) was found between ICP and CPP and a strong correlation between MAP and CPP (r = 0.98829). Moreover, there was a strong correlation between Etdesflurane vs. CPP (r = -0.8769) and MAP (r = -0.8224) and a weak correlation versus ICP (r = 0.15755). A decrease in CPP induced by desflurane was associated with a decrease in MAP but not an increase in ICP. The depressive effect of desflurane on the cerebral and systemic circulations is a consequence of its effector site concentration.

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.

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).

Effect of dexmedetomidine infusion on desflurane requirement and perioperative hemodynamic changes during laparoscopic gastric sleeve operations: a study based on entropy

Context Obese patients undergoing laparoscopic gastric sleeve operations are sensitive to the respiratory depressant effect of opioid analgesics. Alternative methods for analgesia may be beneficial for intraoperative management of those patients. Dexmedetomidine is a highly selective α2 agonist with anesthetic and analgesic sparing properties that makes it an adjuvant in general anesthesia. Aim The aim of this study was to assess the effect of intravenous administration of dexmedetomidine during laparoscopic gastric sleeve operations on desflurane requirements, perioperative hemodynamic changes, and also postoperative recovery. This study was based on entropy to monitor the depth of anesthesia. Patients and methods Eighty patients of American Society of Anesthesiologists II and III who were scheduled for laparoscopic gastric sleeve operations were randomly allocated to two groups of 40 patients each. Dexmedetomidine at a loading dose of 1 μg/kg was given over 10 min before anesthesia induction, followed by 0.5 μg/kg/h maintenance throughout the operation in group II, and saline (placebo) was given in group I at the same volume and rate. Routine induction with propofol, fentanyl, and cisatracurium was carried out. Anesthesia was maintained with desflurane that was adjusted to maintain adequate depth of general anesthesia with response entropy between 40 and 60 and a difference of less than 10 with the state entropy. Desflurane inspired fraction and desflurane expired fraction were monitored. Results End-tidal concentration of desflurane was significantly low at 15, 30, 45, and 60 min of operation. End-tidal concentration of desflurane decreased by 13.2–21.8% with the use of dexmedetomidine in comparison with group I. Systolic blood pressure, diastolic blood pressure, and heart rate were significantly decreased with the use of dexmedetomidine at different time intervals throughout the operation in comparison with group I and in comparison with the baseline in group II. Perioperative fentanyl consumption was significantly low with the use of dexmedetomidine in group II in comparison with group I. It was 325±55 μg in group II in comparison with 178±45 μg in group I. There was no significant difference between the two study groups as regards the extubation time. Pain score was significantly higher in group I in comparison with group II on admission to the postoperative acute care unit, and at 1 and 2 hlater. Conclusion In conclusion, the use of dexmedetomidine as preanesthetic medication followed by infusion during laparoscopic sleeve gastrectomy reduces desflurane requirement, maintains hemodynamic stability due to attenuation of stress response, and reduces the fentanyl requirement during intraoperative and early postoperative period, with decreased risk for respiratory depression in the postoperative acute care unit for morbidly obese patients who are at great risk for obstructive sleep apnea and oxygen desaturation.

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.