End-tidal Desflurane Concentration Research Articles

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).

Effects of oxymorphone hydrochloride or hydromorphone hydrochloride on minimal alveolar concentration of desflurane in sheep.

To establish the minimum alveolar concentration (MAC) of desflurane and evaluate the effects of 2 opioids on MAC in sheep. 8 adult nulliparous mixed-breed sheep. A randomized crossover design was used. Each sheep was evaluated individually on 2 occasions (to allow assessment of the effects of each of 2 opioids), separated by a minimum of 10 days. On each occasion, sheep were anesthetized with desflurane in 100% oxygen, MAC of desflurane was determined, oxymorphone (0.05 mg/kg) or hydromorphone (0.10 mg/kg) was administered IV, and MAC was redetermined. Physiologic variables and arterial blood gas and electrolyte concentrations were measured at baseline (before MAC determination, with end-tidal desflurane concentration maintained at 10%) and each time MAC was determined. Timing of various stages of anesthesia was recorded for both occasions. Mean ± SEM MAC of desflurane was 8.6 ± 0.2%. Oxymorphone or hydromorphone administration resulted in significantly lower MAC (7.6 ± 0.4% and 7.9 ± 0.2%, respectively). Cardiac output at MAC determination for desflurane alone and for desflurane with opioid administration was higher than that at baseline. No difference was identified among hematologic values at any point. Effects of oxymorphone and hydromorphone on durations of various stages of anesthesia did not differ significantly. MAC of desflurane in nulliparous adult sheep was established. Intravenous administration of oxymorphone or hydromorphone led to a decrease in MAC; however, the clinical importance of that decrease was minor relative to the effect in other species.

Effective dose 50 of desflurane for laryngeal mask airway removal in anaesthetized children in cataract surgeries with subtenon block.

Background:Quantification of the depth of desflurane anesthesia required for laryngeal mask airway (LMA) removal in children has been done with the use of intravenous fentanyl or caudal anesthesia. This study aimed to determine the end-tidal concentration of desflurane required for LMA removal in children without the use of caudal or opioid analgesia in children undergoing elective cataract surgery.Materials and Methods:Our study enrolled 25 American Society of Anesthesiologists I and II children aged 2-10 years, undergoing elective cataract surgery. Anesthesia was induced with sevoflurane and oxygen/nitrous oxide using face mask and a size 2 LMA inserted. A subtenon block was administered in all children before surgical incision. Desflurane was used for maintenance of anesthesia. Predetermined end tidal concentration of desflurane was maintained for 10 min at the end of surgery before LMA removal was attempted. End tidal concentrations were increased/decreased using the Dixon up-down method (with 0.5% as a step size) in the next patient depending on the previous patient's response. Patient responses to LMA removal were classified as “movement” or “no movement.”Results:50% effective dose (ED50) for successful removal of the LMA with desflurane in the presence of subtenon block was 3.6% (3.20-3.97%) and that the 95% ED95 was 4.648% (4.15-6.47%).Conclusion:Laryngeal mask airway removal can be successfully accomplished in 50% and 95% anesthetized children at 3.6% and 4.65% end-tidal desflurane concentration.

Effect of intraoperative infusion of ketamine on remifentanil-induced hyperalgesia.

BackgroundOpioid induced hyperalgesia (OIH) is related with high opioid dosage, a long duration of opioid administration, and abrupt discontinuation of infused opioids in anesthetic settings. Ketamine is known to attenuate OIH efficiently, but methods of administration and methods to quantify and assess a decrease in OIH vary. We demonstrated the existence of remifentanil-induced hyperalgesia and investigated the ability of ketamine to attenuate OIH.MethodsSeventy-five patients undergoing laparoscopic gynecologic surgery under remifentanil-based anesthesia were assigned to one of the following groups: (1) group RL (remifentanil 0.05 µg/kg/min), (2) group RH (remifentanil 0.3 µg/kg/min), or (3) group KRH (remifentanil 0.3 µg/kg/min + ketamine 0.5 mg/kg bolus with 5 µg/kg/min infusion intraoperatively). Desflurane was administered for maintenance of anesthesia to target bispectral index scores (40-60) and hemodynamic parameters (heart rate and blood pressure < ± 20% of baseline values). All parameters related to OIH and its attenuation induced by ketamine were investigated.ResultsThere was no significant difference among the three groups related to demographic and anesthetic parameters except the end-tidal concentration of desflurane. Additional analgesic consumption, numerical rating scale scores at 6 and 24 h, and cumulative fentanyl dose were significantly higher in group RH than in the other two groups. The value difference of the Touch-Test sensory evaluation was significantly higher negative in group RH than in the other two groups.ConclusionsRemifentanil-induced hyperalgesia is significantly attenuated by intraoperative bolus and infusion of ketamine. Ketamine also decreased tactile sensitization, as measured by Touch-Test sensory evaluation.

Adsorption of desflurane by the silica gel filters in breathing circuits: an in vitro study.

BackgroundDuring general anesthesia, a heated breathing circuit (HBC) is used to replace the heat and moisture exchange function of the upper airway. One HBC uses an air dryer filter that employs silica gel (SG) as a desiccant. SG is capable of adsorbing many organic compounds. Therefore, we undertook an in vitro study of the adsorption of desflurane by SG filters.MethodsAn HBC was connected to an anesthesia machine, and a test lung was connected to the circuit. The test lung was mechanically ventilated with 2 or 4 L/min of fresh gas flow, with and without the air dryer filter. Desflurane was administered at a 6 vol% on the vaporizer dial setting. The experiment was repeated 15 times in each group. The end-tidal concentrations were measured during the experiments. The air dryer filter weights were measured before and after the experiments, and the times required to achieve the specific end-tidal desflurane concentrations were determined.ResultsSignificant differences in the end-tidal concentrations of desflurane were observed between the control and filter groups (P < 0.001). The filter weights increased significantly after the experiments (P < 0.001). The times required to achieve the same end-tidal desflurane concentrations were different with the application of the air dryer filter (P < 0.001).ConclusionsThe adsorption of desflurane with the use of an air dryer filter was verified in this in vitro study. Careful attention is needed when using air dryer gel filters during general anesthesia.

Time course of end-tidal desflurane concentration during delivery and elimination according to the type and location of filters in a semi-closed circuit system.

BackgroundThe aim of this study was to determine whether the end-tidal concentration of desflurane would be affected by a breathing circuit system filter attached at two different positions in anesthetic breathing circuit systems.MethodsAn artificial lung was ventilated under five different conditions. The first group was without any filter or desflurane (n = 5, sham), the second was with desflurane but without any filter (n = 10, control), the third group had a bacterial filter on the expiratory limb (n = 10), and the fourth and fifth groups had a viral/bacterial filter added on the expiratory limb (n = 10) or at the Y-piece of the breathing circuit (n = 10), respectively. In all groups except the sham, administration of 10% desflurane was performed for 5 minutes and then stopped for 5 minutes.ResultsThe mean (SD) end-tidal concentration of desflurane for the groups described above peaked at 0 (0), 9.8 (0.1), 9.8 (0.1), 8.5 (0.1), and 6.7% (0.1) (P < 0.001), respectively. There was no difference in the desflurane concentrations and the expired tidal volume over time between the control and bacterial group, but there was a significant difference between the control and the fourth and fifth groups (P < 0.001).ConclusionsFilters can affect the expiratory desflurane concentration during anesthesia.

Direct Comparison of the Effect of Desflurane and Sevoflurane on Intraoperative Motor-evoked Potentials Monitoring

During spinal surgery, intraoperative monitoring of motor-evoked potentials (MEPs) is a useful means of assessing the intraoperative integrity of corticospinal pathways. However, MEPs are known to be particularly sensitive to the suppressive effects of inhalational halogenated anesthetic agents. To investigate the effects of increasing end-tidal concentrations of desflurane and sevoflurane anesthesia in a background of propofol and remifentanil with multipulse cortical stimulation on intraoperative monitoring of MEPs. In this randomized crossover trial, 14 consecutive patients (7 in each arm) undergoing major spine surgery, under a background anesthetic of propofol (75 to 125 mcg/kg/min) and remifentanil (0.1 to 0.2 mcg/kg/min), were randomly assigned to receive the sequence of inhalational agents studied: either DES-SEVO (desflurane followed by sevoflurane); or SEVO-DES (sevoflurane followed by desflurane). Multiples (0.3, 0.5, and 0.7) of minimum alveolar concentration (MAC) of desflurane and sevoflurane were administered. After a washout period of 15 minutes using high fresh oxygen/air flows, each of the patients then received the other gas as the second agent. Cortical stimulation was achieved with a train of 5 equivalent square pulses, each 0.05 ms in duration, delivered at 2 ms intervals. MEP recordings were made in the upper limb (UL) from first dorsal interosseus and lower limb (LL) from tibialis anterior with subdermal needle electrodes. At 0.3 MAC desflurane, there was no statistical significant difference in transcranial-evoked MEP amplitudes from the baseline in both UL and LL stimulation. However, this was not the case for sevoflurane for which even a low concentration at 0.3 MAC significantly depressed MEP amplitudes of LL (but not UL) from baseline value. Desflurane at 0.5 and 0.7 MAC depresses LL MEP to 58.4% and 59.9% of baseline, respectively (P<0.05), whereas sevoflurane at 0.3, 0.5, and 0.7 MAC depresses LL MEP to 66.2%, 41.3%, and 25.3% of baseline, respectively (P<0.05). There was no difference in latency of the responses at any MAC. Inhalational anesthetic agents (sevoflurane >desflurane) suppress MEP amplitudes in a dose-dependent manner. The use of 0.3 MAC of desflurane (but not sevoflurane) provided good MEP recordings acceptable for clinical interpretation for both upper and LLs. The LL appears to be more sensitive to anesthetic-induced depression compared with the UL. All patients studied had normal neurological examination hence, these results may not be applicable to those with preexisting deficits.

The Effect of Different End-tidal Desflurane Concentrations on Bispectral Index Values in Normal Children and Children with Cerebral Palsy.

In this study, we aimed to compare the effects of different intraoperative end-tidal desflurane concentrations on bispectral index (BIS) values in normal children and children with cerebral palsy. Twenty normal children (Group N) and 20 children with non-communicative/nonverbal cerebral palsy (Group CP), between 2 and 15 years of age, undergoing elective orthopaedic surgery were included in the study. Following premedication with midazolam, anaesthesia was induced by infusing 1% propofol at a rate of 200 mL hr(-1) until BIS reached 50. Heart rate, blood pressure and BIS values were recorded before and after the induction of anaesthesia, at steady-state end-tidal concentrations of 4% and 6% desflurane, and after emergence from anaesthesia. A p value <0.05 was considered significant in the statistical analyses, including Kolmogorov-Smirnov, t-test, paired samples t-test and chi-square test. The time to extubation and eye opening after discontinuation of anaesthesia was longer in Group CP. BIS values before the induction of anaesthesia, at a steady-state end-tidal desflurane concentration of 4% and after emergence from the anaesthetic were significantly lower in Group CP. At a steady-state end-tidal desflurane concentration of 6%, BIS values were slightly lower in Group CP but this difference was not statistically significant. Based on the data obtained, we concluded that BIS monitoring in children with cerebral palsy can be useful in terms of decreasing adverse effects and drug interactions due to multiple drug usage by reducing the use of anaesthetic agents and improving emergence from the anaesthetic.

The Effects of Bispectral Index and Neuromuscular Blockade Monitoring on the Depth of Anaesthesia and Recovery in Cardiac Patients Under Desflurane Anaesthesia.

In this study, we aimed to investigate the effects of bispectral index (BIS) and neuromuscular blockade monitoring on the depth of anaesthesia and recovery in cardiac patients, scheduled to undergo open cholecystectomy operation with desflurane anaesthesia. After the approval of the Ethics Committee and consent from the patients, patients were randomly divided into two groups. All patients received standard induction drugs, and 4-6% desflurane was used for maintenance of anaesthesia. In Group I, the anaesthesiologist was blind to BIS, and end-tidal volatile agent concentration (ETVAC) of desflurane was titrated according to the patients' hemodynamic changes. In Group II, ETVAC of desflurane was titrated to maintain BIS at 50-60. The hemodynamic data, BIS values, end-tidal volatile agent concentration (ETVAC) and train of four (TOF) values were recorded at pre-induction, post-induction, post-intubation, 1st and 5th minutes after surgical incision and then every 15 min. At the end of the operation, extubation time and the time to reach an Aldrete recovery score ≥9 were recorded in each group. Additionally, neuromuscular agent and narcotic agent doses were recorded. The BIS values were lower for Group I in all times, except pre- and post-induction times (p<0.05). ETVAC values of all times were lower for Group II (p<0.05). The requirement of volatile agent, which was given according to BIS monitoring, was lower than in the standard technique, but it is considered not to affect the early extubation, recovery and neuromuscular agent requirement dependent on TOF monitoring.

Pulsoksymetria nowej generacji w ocenie obwodowej perfuzji tkankowej w czasie znieczulenia ogólnego — porównanie propofolu i desfluranu

A pulse oximeter is a standard device for perioperative monitoring. It is well known that the early detection of tissue hypoxia is of great importance. It has been made easier due to a new generation pulse oximetry device from Masimo. This enables measurements of the peripheral perfusion index (PI) in real time. It has been found that volatile anaesthetics such as sevoflurane and desflurane increase the perfusion index. As we know, no data is available about perfusion index during propofol/remifentanil total intravenous anaesthesia. ASA I and II class women scheduled for elective gynaecological surgery were eligible for the study. Patients were divided into two groups: group P receiving propofol/remifentanil intravenous anaesthesia and group D receiving desflurane/fentanyl general anaesthesia. PI was noted before anaesthesia, after remifentanil/fentanyl injection, after endotracheal intubation, at the beginning of surgery, during the procedure at ten minute intervals, at the end of the procedure, after awakening, after extubation and before discharge to the ward. Eighty-three patients were enrolled to the study. In both groups, PI increased significantly from the start to the end of surgery. There was a significant correlation between PI and end-tidal desflurane concentration (r = 0.807; P = 0.001). No correlation was found between propofol or remifentanil concentrations and PI. Both intravenous propofol/remifentanil and desflurane/fentanyl general anaesthesia increase peripheral perfusion. An increase in end-tidal desflurane concentration raises peripheral perfusion.

Minimum alveolar concentration of desflurane with caudal analgesia for laryngeal mask airway removal in anesthetized children

Regional blocks have been shown to decrease the requirement of anesthetic agents. This study was conducted to determine the optimal endtidal concentrations of desflurane for removal of Laryngeal mask airway in children in presence of caudal block. Twenty-two children of ASA status I between the age group of 2-10 year undergoing infraumbilical surgery were enrolled in the study. General anesthesia was induced with sevoflurane and oxygen given via mask and laryngeal mask airway inserted. Caudal injection of bupivacaine 0.25%, 1 ml·kg(-1) was administered according to Armitage regimen. Desflurane was used for maintenance of anesthesia. Predecided endtidal concentration of desflurane was maintained for 10 min at the end of surgery and laryngeal mask airway removed. Target concentration in the next patient was thereafter determined by the Dixon up-down method (with 0.5% as a step size). 5% endtidal concentration was kept as the starting concentration. If removal of laryngeal mask airway was not associated with any coughing, teeth clenching, gross purposeful movement, breath holding or laryngospasm, during or within 1 min after removal, it was considered as successful. In the presence of caudal analgesia, endtidal concentration of desflurane required for successful laryngeal mask airway removal in 50% (ED50) children was 3.39 ± 0.38% by Dixon's method. Laryngeal mask airway can be successfully removed in 50% of anesthetized children without coughing, moving, or any other airway complications at an endtidal desflurane concentration of 3.4% in the presence of caudal analgesia.

Entropy guided end tidal desflurane concentration during living donor liver transplantation

Entropy guided end tidal desflurane concentration during living donor liver transplantation

Entropy-guided end-tidal desflurane concentration during living donor liver transplantation

Background:The three phases of living donor liver transplantation (LDLT) represent different liver conditions. The aim is to study the required end-tidal desflurane concentration (ET-Des) guided with entropy monitoring for the depth of anesthesia.Methods:After the Ethics and Research Committee approval, 40 patients were included in this prospective study. Anesthesia was maintained with Desflurane-O2-air. State entropy (SE) and Response entropy (RE) were kept between 40 and 60.Results:Age and Model for End-stage Liver Disease (MELD) score were 45±10 years and 15.43±3.92, respectively. ET-Des were significantly lower in the anhepatic phase (2.8±0.4%) than in the pre-anhepatic and neohepatic phases (3.3±0.3%, 3.47±0.3%, respectively, P<0.001). The SE and RE for pre-anhepatic, anhepatic, and neohepatic phases were (45.6±3.7, 47.4±3.2), (44.7±2.1, 46.4±2.04), and (46.1±3.3, 47.9±3.3), respectively, with no significant changes between the phases, P > 0.05. Total operative time was 651±88 minutes, and for each phase it was 276±11, 195±55, and 191±24 minutes, respectively. Significant changes were found in hemoglobin g/dl and hematocrit % between the three phases (10.28±1.5, 30.48±4.3), (9.45±1.34, 28.36±4.1), and (8.88±1.1, 26.63±3.5), P<0.05. The heart rate and mean blood pressures were stable despite the cardiac index demonstrated a significant reduction during the anhepatic phase (2.99±0.22) when compared to the pre-anhepatic and neohepatic phases (3.60±0.29) and (4.72±0.32), respectively, (P<0.05). There was a significant correlation between CI and ET-Des% (r=0.604, P<0.05).Conclusion:Inhalational anesthetic requirements differed from one phase to another during LDLT, with requirements being the least during the anhepatic phase. Monitoring of the anesthesia depth was required, to avoid excess administration, which could compromise the hemodynamics before the critical time of reperfusion.

Effect-Site Concentration of Remifentanil for Minimizing Cardiovascular Changes by Inhalation of Desflurane

PurposeThis study aims to investigate the most appropriate effect-site concentration of remifentanil to minimize cardiovascular changes during inhalation of high concentration desflurane.Materials and MethodsSixty-nine American Society of Anesthesiologists physical status class I patients aged 20-65 years were randomly allocated into one of three groups. Anesthesia was induced with etomidate and rocuronium. Remifentanil was infused at effect-site concentrations of 2, 4 and 6 ng/mL in groups R2, R4 and R6, respectively. After target concentrations of remifentanil were reached, desflurane was inhaled to maintain the end-tidal concentration of 1.7 minimum alveolar concentrations for 5 minutes (over-pressure paradigm). The systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR) and end-tidal concentration of desflurane were measured for 5 minutes.ResultsThe end-tidal concentration of desflurane increased similarly in all groups. The SBP, DBP, MAP and HR within group R4 were not significantly different as compared with baseline values. However, measured parameters within group R2 increased significantly 1-3 minutes after desflurane inhalation. The MAP within group R6 decreased significantly at 1, 2, 4, and 5 minutes (p<0.05). There were significant differences in SBP, DBP, MAP and HR among the three groups 1-3 minutes after inhalation (p<0.05). The incidence of side effects such as hyper- or hypo-tension, and tachy- or brady-cardia in group R4 was 4.8% compared with 21.8% in group R2 and 15.0% in group R6.ConclusionThe most appropriate effect-site concentration of remifentanil for blunting hemodynamic responses by inhalation of high concentration desflurane is 4 ng/mL.

Duration effect of desflurane anesthesia and its awakening time and arterial concentration in gynecologic patients

OBJECTIVES:To determine the awakening arterial blood concentration of desflurane and its relationship with the end-tidal concentration during emergence from various durations of general anesthesia.METHOD:In total, 42 American Society of Anesthesiologists physical status class I-II female patients undergoing elective gynecologic surgery were enrolled. General anesthesia was maintained with fixed 6% inspiratory desflurane in 6 l min-1 oxygen until shutoff of the vaporizer at the end of surgery. One milliliter of arterial blood was obtained for desflurane concentration determination by gas chromatography at 20 and 10 minutes before and 0, 5, 10, 15, and 20 minutes after the discontinuation of desflurane and at the time of eye opening upon verbal command, defined as awakening. Concentrations of inspiratory and end-tidal desflurane were simultaneously detected by an infrared analyzer.RESULTS:The mean arterial blood concentration of desflurane was 1.20% at awakening, which correlated with the awakening end-tidal concentration of 0.96%. The mean time from the discontinuation of desflurane to eye opening was 5.2 minutes (SD = 1.6, range 3-10), which was not associated with the duration of anesthesia (60-256 minutes), total fentanyl dose, or body mass index (BMI).CONCLUSIONS:The mean awakening arterial blood concentration of desflurane was 1.20%. The time to awakening was independent of anesthetic duration within four hours. Using well-assisted ventilation, the end-tidal concentration of desflurane was proven to represent the arterial blood concentration during elimination and could be a clinically feasible predictor of emergence from general anesthesia.

Effect of bispectral index monitoring on desflurane consumption and recovery time in morbidly obese patients undergoing laparoscopic sleeve gastrectomy.

Background:Morbid obesity magnifies the importance of the fat–blood solubility coefficient of the anesthetic in its relation to emergence and recovery. Using bispectral index (BIS) monitoring for the titration of the administration of inhaled anesthetics such as desflurane may permit a less consumption and more rapid recovery from desflurane anesthesia in morbidly obese patients, which enables earlier maintenance of a patent airway, better protection against aspiration, and better oxygenation.Objective:The aim of this study was to investigate the effect of BIS monitoring on postoperative extubation and recovery times, and intraoperative desflurane consumption in morbidly obese patients undergoing laparoscopic sleeve gastrectomy under general anesthesia using desflurane for maintenance.Patients and Methods:Forty morbidly obese patients were randomly enrolled in this study and divided into two groups of 20 patients each: Non-BIS group and BIS group. End-tidal desflurane concentration, mean blood pressure, and heart rate were regularly recorded. Recovery times (eye opening to verbal commands, time to extubation, and orientation to time, place, and person) and the time to achieve a modified Aldrete score of ≥ 9 were recorded by blinded study anesthesia nurse. Desflurane consumption was calculated in milliliters through gas usage option of Datex-Ohmeda S/5 anesthesia machine.Results:The mean end-tidal concentrations of desflurane were significantly decreased in the BIS group compared to the non-BIS group (P < 0.05). The mean desflurane consumption and cost were significantly lower in the BIS group (124.8 ± 5.1 ml/patient) compared to the non-BIS group (150.6 ± 6.5 ml/patient) (P < 0.05). Recovery times were significantly shorter in the BIS group versus non-BIS group (P < 0.05).Conclusion:The use of BIS monitoring was effective in reducing intraoperative desflurane requirement (cost) and in shortening early recovery times after laparoscopic sleeve gastrectomy in morbidly obese patients without compromising the hemodynamic stability, adequacy of anesthesia, or patient outcome.

Hyperventilation accelerates the rise of arterial blood concentrations of desflurane in gynecologic patients

OBJECTIVES:Under a constant inspired concentration, the uptake of a volatile anesthetic into the arterial blood should mainly be governed by alveolar ventilation, according to the assumption that the patient's cardiac output remains stable during anesthesia. We investigated whether ventilation volume affects the rate of desflurane uptake by examining arterial blood concentrations.METHOD:Thirty female patients were randomly allocated into the following three groups: hyperventilation, normal ventilation and hypoventilation. Hemodynamic variables were measured using a Finometer, inspiratory and end-tidal concentrations of desflurane were measured by infrared analysis, and the desflurane concentration in the arterial blood (Ades) was analyzed by gas chromatography.RESULTS:During the first 10 minutes after the administration of desflurane, the Ades was highest in the hyperventilation group, and this value was significantly different from those obtained for the normal and hypoventilation groups. In addition, hyperventilation significantly increased the slope of Ades-over-time during the first 5 minutes compared with patients experiencing normal ventilation and hypoventilation, but there were no differences in these slopes during the periods from 5-10, 10-20 and 20-40 minutes after the administration of desflurane. This finding indicates that there were no differences in desflurane uptake between the three groups after the first 5 minutes within desflurane administration.CONCLUSIONS:Hyperventilation accelerated the rate of the rise in Ades following desflurane administration, which was time-dependent with respect to different alveolar ventilations levels.

The effect of intravenous labetalol administration on hemodynamic responses during desflurane inhalation.

BackgroundInspired concentrations of desflurane ≥ 1 minimum alveolar anesthetic concentration (MAC) have been related to sympathetic stimulation such as hypertension and tachycardia. The current study examined whether labetalol, an α1 and β-adrenergic antagonist would blunt these hemodynamic responses.MethodsFifty-four ASA physical status I patients, aged 20-60 years, were enrolled in this study. The patients were randomly divided into 2 groups. The breathing circuit was primed with an end-tidal desflurane concentration of 1.2 MAC in 6 L/min O2. Normal saline 5 ml or labetalol 0.3 mg/kg was injected into groups S and L respectively. After 5 minutes, anesthesia was induced with intravenous etomidate 0.2 mg/kg and vecuronium 0.1 mg/kg. Each patient inhaled desflurane through a tight fitting facemask. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and end-tidal concentration of desflurane (et-des) were measured at 5 minutes after saline or labetalol injection (baseline) and every 1 minute for 5 minutes after desflurane inhalation and for 2 minutes after intubation.ResultsIn the saline injection group (group S), desflurane inhalation increased heart rate and blood pressure, while labetalol 0.3 mg/kg attenuated the heart rate and blood pressure increase in group L. After tracheal intubation, heart rate and blood pressure were significantly lower in group L than in group S.ConclusionsThese results demonstrate that administration of intravenous labetalol is effective in attenuating tracheal intubation and desflurane-induced hemodynamic responses.

Effect of a target-controlled infusion of remifentanil in combination with desflurane during the "maintenance" phase of general anesthesia

BackgroundThe goal of this study was to determine the optimal target-controlled concentration of remifentanil combined with desflurane, by using a more widely and decreasing end-tidal concentration of desflurane.MethodsNinety ASA I patients, who underwent general anesthesia for elective orthopedic or extremity surgeries, were registered and randomly allocated to receive either a target-controlled concentration of 1 ng/ml (group R1), 2 ng/ml (group R2) remifentanil, or desflurane only without remifentanil infusion (group D). Mean arterial pressure (MAP) and heart rate (HR) were recorded at 5-min intervals from after a 10-15 min period of surgical incision to before a 10-min period prior to the end of an operation. End-tidal concentration of desflurane was increased or decreased in proportion to the changes in MAP and HR. If the value of bispectral index (BIS) was from 60-62 for more than 2 min or systolic blood pressure would fall below 90 mmHg, the patient was excluded from the study to prevent a risk of "explicit awareness" and shock.ResultsThe end-tidal desflurane concentration was lower in the group receiving 1 ng/ml (5.2 ± 0.5 vol%; P < 0.001) and 2 ng/ml remifenanil (4.4 ± 0.5 vol%; P < 0.001) compared to patients in group D (7.9 ± 0.5 vol%).ConclusionsWe recommend the use of 2 ng/ml or less remifentanil combined with desflurane for decreasing concentrations of desflurane without significant side effects, during the "maintenance" phase, and not during the induction phase of general anesthesia.

Minimum alveolar concentration of desflurane with fentanyl for laryngeal mask airway removal in anesthetized children

Desflurane provides rapid emergence from anesthesia. So, it can be used for the removal of a laryngeal mask airway in an anesthetized child. We conducted this study to determine the optimal endtidal concentrations of desflurane with fentanyl that would allow removal of a laryngeal mask airway without airway complication in children. Thirty-six children of American Society of Anesthesiologist status I between 1 and 10 year of age undergoing ophthalmic surgery were recruited. General anesthesia was induced with sevoflurane and oxygen given via mask and laryngeal mask airway inserted. Anesthesia was maintained with desflurane in 100% oxygen. At the end of the surgery, predetermined target concentration was maintained for 10 min and laryngeal mask airway removed. Each target concentration at the time of removal was predetermined by the Dixon up-down method (with 0.5% as a step size) starting at 5% endtidal concentration. A removal accomplished without coughing, teeth clenching, gross purposeful movement, breath holding, or laryngospasm, during or within 1 min after removal, was considered to be successful. Endtidal concentration of desflurane required for successful laryngeal mask airway removal in 50% (ED50) was 3.56% desflurane (95% confidence limits, 3.22-3.87%) along with fentanyl. Removal of laryngeal mask airway can be safely accomplished without coughing, moving, or any other airway complications at 3.57% endtidal concentrations of desflurane with fentanyl in 50% of anesthetized children.