Recovery after anaesthesia for pulmonary surgery: desflurane, sevoflurane and isoflurane

We have studied maintenance and recovery profiles after general anaesthesia with sevoflurane, desflurane and isoflurane in 100 patients undergoing pulmonary surgery. End-tidal concentrations of anaesthetic required to maintain mean arterial pressure and heart rate within 20% of baseline values were 1.4 +/- 0.6% for sevoflurane, 3.4 +/- 0.9% for desflurane and 0.7 +/- 0.3% for isoflurane. The three anaesthetics had comparable haemodynamic effects and arterial oxygenation during one- lung ventilation. Emergence was twice as fast with desflurane than with sevoflurane or isoflurane (mean times to extubation: 8.9 (SD 5.0) min, 18.0 (17.0) min and 16.2 (11.0) min for desflurane, sevoflurane and isoflurane, respectively). Early recovery (Aldrete score, cognitive and psychomotor functions) was also more rapid after desflurane. In pulmonary surgery, desflurane, but not sevoflurane, allowed more rapid emergence and earlier recovery than isoflurane.      

Rocuronium potency and recovery characteristics during steady-state desflurane, sevoflurane, isoflurane or propofol anaesthesia

We have studied the potency and recovery characteristics of rocuronium during 1.25 MAC of isoflurane, desflurane, sevoflurane or propofol anaesthesia in 84 patients using electromyography. Potency was determined by a cumulative bolus technique. The mean ED50 of rocuronium was 169 (SD 41), 126 (32), 121 (28) and 136 (25) micrograms kg-1 during propofol, isoflurane, sevoflurane and desflurane anaesthesia, respectively (ns), and ED90 values were 358 (62), 288 (29), 289 (28) and 250 (28) micrograms kg-1, respectively. The reduction in ED90 was statistically significant for all three inhalation anaesthetics (P < 0.05) compared with propofol. After 120 min, the cumulative infusion rate of rocuronium to obtain twitch depression of 90-95% was 9.0 (1.9), 6.3 (1.6), 6.1 (2.0) and 6.1 (1.1) micrograms kg-1 min-1 during propofol, isoflurane, sevoflurane and desflurane anaesthesia, respectively (P < 0.01). Recovery index was 22 (13), 27 (10), 28 (13) and 26 (14) min under propofol, isoflurane, sevoflurane and desflurane anaesthesia, respectively (ns). There were no significant differences between the three potent inhalation anaesthetics in relation to potency, infusion requirements or recovery characteristics of rocuronium.      

Influence of volatile anaesthetics on hypercapnoeic ventilatory responses in mice with blunted respiratory drive

Background. Subanaesthetic concentrations of volatile anaestheticssignificantly affect the respiratory response to hypoxia andhypercapnoeia. Individuals with an inherited blunted respiratorydrive are more affected than normal individuals. To test thehypothesis that subjects with blunted hypercapnoeic respiratorydrive are diversely affected by different anaesthetics, we studiedthe effects of three volatile anaesthetics on the control ofbreathing in C3H/HeJ (C3) mice, characterized by a blunted hypercapnoeicrespiratory response. Methods. Using whole body plethysmography, we assessed respiratoryrate (RR) and pressure amplitude in 11 male C3 mice at rest,during anaesthesia with isoflurane, sevoflurane or desflurane,and during recovery. To test respiratory drive, mice were exposedto 8% carbon dioxide. Data were analysed by two-way-analysisof variance with post hoc tests and Bonferroni correction. Results. RR was unaffected during sevoflurane anaesthesia upto 1.0 MAC. Likewise, sevoflurane at 1.5 MAC affected RR lessthan either isoflurane (P=0.0014) or desflurane (P=0.0048).The increased RR to a carbon dioxide challenge was blocked byall three anaesthetics even at the lowest concentration, andremained depressed during recovery (P<0.0001). Tidal volumewas unaffected by all three anaesthetics. Conclusions. In C3 mice, spontaneous ventilation was less affectedduring sevoflurane compared with either isoflurane or desfluraneanaesthesia. However, the RR response to hypercapnoeia was abolishedat 0.5 MAC for all the anaesthetic agents and remained depressedeven at the end of recovery. Our data suggest that differentvolatile anaesthetics have varying effects on the control ofbreathing frequency but all block the respiratory response tocarbon dioxide. Therefore, a genetic predisposition to a bluntedcarbon dioxide response represents a susceptibility factor thatinteracts with hypercapnoeic hypoventilation during maintenanceof anaesthesia and in the emergence from anaesthesia, regardlessof the agent used. Br J Anaesth 2004; 92: 697–703     

Postoperative Results after Desflurane or Sevoflurane Combined with Remifentanil in Morbidly Obese Patients

Background: This randomized prospective study with blinded postanesthesia care unit (PACU) observers compared the recovery profiles in morbidly obese patients who received sevoflurane or desflurane for maintenance of anesthesia in combination with a remifentanil target controlled infusion (TCI). Methods: 50 morbidly obese patients scheduled for laparoscopic gastric banding were included to receive BIS-guided sevoflurane or desflurane anesthesia with BIS-triggered inhalation boli in combination with remifentanil TCI. In the PACU, the following recovery scores were investigated: Modified Aldrete score, a modified Observers' Assessment of Alertness/Sedation Scale (OAA/S), pain numerical rating scale (NRS), oxygen saturation (SpO₂) and postoperative nausea and vomiting (PONV). Results: OAA/S and NRS pain scores showed a similar evolution in both groups from the moment of PACU admission up to 120 minutes after admission. In both groups, patients showed no serious hypoxemia during PACU stay. Incidence of PONV was shorter lasting in the sevoflurane group compared to the desflurane group. Conclusions: No clinically relevant difference was found in recovery in the PACU between morbidly obese patients anesthetized with desflurane or sevoflurane. Both agents resulted in satisfactory recovery in morbidly obese patients.     

Measuring the costs of inhaled anaesthetics

The cost of inhalation anaesthesia has received considerablestudy and is undoubtedly reduced by the use of low fresh gasflows. However, comparison between anaesthetics of the economiesachievable has only been made by computer modelling. We havecomputed anaesthetic usage for MAC-equivalent anaesthesia withisoflurane, desflurane, and sevoflurane in closed and open breathingsystems. We have compared these data with those derived duringclinical anaesthesia administered using a computer-controlledclosed system that measures anaesthetic usage and inspired concentrations.The inspired concentrations allow the usage that would haveoccurred in an open system to be calculated. Our computed predictionslie within the 95% confidence intervals of the measured data.Using prices current in our institution, sevoflurane and desfluranewould cost approximately twice as much as isoflurane in opensystems but only about 50% more than isoflurane in closed systems.Thus computer predictions have been validated by patient measurementsand the cost saving achieved by reducing the fresh gas flowis greater with less soluble anaesthetics. Br J Anaesth 2001; 87: 559–63     

Sevoflurane: an ideal agent for adult day‐case anesthesia?

Sevoflurane has several properties which make it potentially useful as a day case anaesthetic. Following induction of anaesthesia with propofol, awakening from sevoflurane is faster compared to isoflurane, faster or similar compared to propofol and comparable (in the majority of studies) to desflurane. Subsequent recovery and discharge is generally similar following all agents. Sevoflurane may also be used to induce anaesthesia, which is generally well-received and causes less hypotension and apnoea compared to propofol. When used as a maintenance anaesthetic, the incidence of postoperative nausea and vomiting after sevoflurane is comparable to other inhaled anaesthetics, but this complication appears more common after inhaled inductions. The tolerability and low solubility of sevoflurane facilitate titration of anaesthesia and may reduce the need for opioid analgesia, which in turn may limit the occurrence of nausea and vomiting.     

Neuromuscular blocking effects of rocuronium during desflurane, isoflurane, and sevoflurane anaesthesia

Purpose

To determine the magnitude of the potentiation of rocuronium by desflurane, isoflurane and sevoflurane 1.5 MAC anaesthesia.

Methods

In a prospective, randomised, study in 80 patients, the cumulative dose-effect curves for rocuronium were determined during anaesthesia with desflurane, sevoflurane and isoflurane (with N₂O 70%, 15 min steady state) or total intravenous anaesthesia (TIVA) using propofol/fentanyl. Neuromuscular block was assessed by acceleromyography (TOF-Guard®) after train-of-four (TOF) stimulation of the ulnar nerve (2Hz every 12sec, 200 μsec duration), Rocuronium was administered in increments of 100 μg·kg^?1 until first twitch (T₁) depression > 95%.

Results

Rocuronium led to more pronounced T₁ depression with desflurane or sevoflurane anaesthesia than with TIVA. The ED₅₀ and ED₉₅ were lower during desflurane (95 ± 25 and 190 ± 80 μg·kg^?1) and sevoflurane (120 ±30 and 210 ± 40 μg·kg^?1) than with TIVA (150 ± 40 and 310 ± 90 μg·kg^?1) (P < .01), while the difference was not significant for isoflurane (130 ± 40 and 250 ± 90 μg·kg^?1). Following equi-effective dosing (T₁ > 95%) the duration to 25% T₁ recovery, recovery index (25/75), and TOF_0.70 was: 13.2 ± 1.8, 12.7 ± 3.4, and 26.9 ± 5.7 min during anaesthesia with desflurane; 15.5 ± 5.0, 11.4 ± 3.8, and 31.0 ± 6.0 min with sevoflurane; 13.9 ± 4.7, 10.7 ± 3.3, and 26.3 ± 8.9 min with isoflurane; and 13.9 ± 3.9, 11.3 ± 5.7, and 27.5 ± 8,2 min with TIVA anaesthesia (P: NS).

Conclusion

Interaction of rocuronium and volatile anaesthetics resulted in augmentation of the intensity of neuromuscular block but did not result in significant effects on duration of or recovery from the block.     

Early recovery, cognitive function and costs of a desflurane inhalational vs. a total intravenous anaesthesia regimen in long-term surgery

BACKGROUND: The purpose of the study was to compare time of recovery, return of cognitive function, post-anaesthetic care unit (PACU) stay and costs of a propofol/remifentanil (TIVA) with a desflurane/fentanyl-based anaesthesia (desflurane group) in surgical procedures lasting more than 150 min. METHODS: Forty-nine patients undergoing elective abdominal prostatectomy were allocated randomly to receive bispectal index (BIS)-controlled desflurane/fentanyl (n=24) or propofol/remifentanil (n=25). Awakening, clinical recovery, direct drug acquisition and post-operative pain treatment were documented. Cognitive skills were tested using the Mini-Mental Status (MMST) test. RESULTS: Extubation was significantly faster with desflurane (6.9+/-3.5 min) than with TIVA (11.2+/-4.0 min) as well as times for stating name and date of birth (desflurane: 6.1+/-3.9 and 6.6+/-4.0 min; TIVA: 12.4+/-11.5 min and 13.4+/-11.3 min). There were no significant differences in PACU discharge times or MMS scores between the groups. Significantly more patients suffered post-operative nausea and vomiting (PONV) in the desflurane (33% vs. 0%) than the TIVA group. Overall costs were significantly higher in the TIVA (58.8+/-11.6 euro) than in the desflurane group (35.0+/-5.7 euro). CONCLUSION: Patients undergoing prolonged surgical procedures showed a faster early recovery after desflurane/fentanyl than using TIVA, whereas stay in the PACU and recovery of cognitive function were similar in both groups. Costs of a TIVA regimen were significantly higher than using a desflurane-based anaesthesia technique.     

Neue Inhalationsanästhetika

Recently, two new halogenated volatile anaesthetics, sevoflurane and desflurane, have been approved for clinical use in Germany. Their low solubility in blood is the most important common property, and this represents the most obvious difference from the inhalational anaesthetics currently used. Extensive clinical and experimental evaluations have confirmed the superior pharmacokinetic properties predicted. Both sevoflurane and desflurane provide more rapid emergence from anaesthesia, permit easier titration of the anaesthetic dose during maintenance and offer more rapid recovery from anaesthesia. For sevoflurane, there are additional advantages: a pleasant odor, negligible airway irritation, and excellent pharmacodynamic characteristics that even provide cardiovascular stability comparable to isoflurane. A certain disadvantage and source of potential nephrotoxicity result from the metabolism of sevoflurane (2–5%) to anorganic fluoride and degradation to compound A in carbon dioxide absorbents. The extensive clinical data reported to date have revealed no evidence that sevoflurane has adverse renal effects. New insight into the pathomechanism of nephrotoxicity associated with either production of fluoride or compound A may well support clinical experience. Desflurane strongly resists in vivo metabolism and because of this it appears to be devoid of toxicity. Nevertheless, potential side-effects may result from degradation in dry absorbents and subsequent release of CO, from its extreme pungency and irritating airway effects. Thus, desflurane is not recommended for induction of anaesthesia, especially in children. The tendency for desflurane transiently to stimulate sympathetic activity, especially at concentrations above 1.0 MAC, limits its application in patients with cardiac disease.     

Anaesthesia with desflurane-nitrous oxide in elderly patients. Comparison with isoflurane-nitrous oxide

BACKGROUND: Desflurane is a new volatile anaesthetic, very little soluble. We wished to compare efficacy, safety, and emergence and recovers; profiles of desflurane-N2O versus isoflurane-N2O anaesthesia in elderly patients. METHODS: Experimental design: single blind, prospective randomised study. Setting: operating rooms of two major teaching hospitals affiliated with the University of Milan. Patients: fifty-seven patients ASA physical status II or III, aged 65 or older, undergoing urological (non-endoscopic), orthopaedic or gynaecological (non-laparoscopic) surgery of at least one hour duration, were randomly assigned to receive general anaesthesia with either desflurane or isoflurane in 60% N2O- 40% O2, after standardised premedication and induction. MEASUREMENTS: vital signs, end-tidal agent, narcotic requirement, and adverse event appearance were monitored throughout the study. RESULTS: Twenty-eight patients received desflurane and 29 isoflurane. Demographics, anaesthesia duration and exposure, and intraoperative fentanyl requirement were comparable in the two groups. Immediate emergence from anaesthesia (time to extubation and hand grip on command) was faster in desflurane group, albeit not significantly (8.4 +/- 6.4 vs 11.0 +/- 6.5 min and 8.6 +/- 6.0 vs 11.8 +/- 6.0); on the contrary, early recovery (time to state the name and date of birth) was significantly shorter in patients receiving desflurane (11.1 +/- 6.2 vs 17.3 +/- 7.8 min and 13.1 +/- 6.0 vs 20.9 +/- 10.9 min). Only 24 patients (12 in desflurane and 12 in isoflurane group) did need postoperative fentanyl administration; among them, requirement was significantly higher in desflurane patients (3.4 +/- 1.1 vs 2.4 +/- 1.3 micrograms.kg-1. Total time in recovery room was not different between anaesthetics, as well as adverse event prevalence and severity. CONCLUSIONS: Early recovery in elderly patients is faster after desflurane than isoflurane anaesthesia; this might contribute to increased requirement of postoperative analgesia. Occurrence of adverse event is comparable between the two anaesthetics.     

The impact of isoflurane, desflurane, or sevoflurane on the frequency and severity of postoperative nausea and vomiting after lumbar disc surgery

STUDY OBJECTIVE: To test the hypothesis that anesthesia with the low-soluble inhalation anesthetics, sevoflurane, and desflurane, may result in a lower frequency and severity of postoperative nausea and vomiting (PONV) than anesthesia with isoflurane. DESIGN: Prospective, observational study. SETTING: Postoperative care unit and neurosurgical ward at a university hospital. PATIENTS: 625 ASA physical status I, II, and III patients undergoing elective lumbar disc surgery with general anesthesia were included in this study. INTERVENTIONS: Patients were enrolled sequentially to receive either 0.7%-1.2% isoflurane (year 2002), 3.5%-5.5% desflurane (year 2003), or 1.2%-1.9% sevoflurane (year 2004) for maintenance of anesthesia without nitrous oxide. Study personnel, general anesthesia management, and surgical technique remained unchanged over the three-year study period. MEASUREMENTS: Occurrence of PONV within 24 hours of the end of surgery was recorded. Secondary outcome measures were occurrence of multiple PONV episodes, maximum severity, time to the first PONV event, need for rescue medication, difference between the occurrence of PONV (indicator variable) and the expected risk of PONV (based on the Apfel score). MAIN RESULTS: Type of inhalation anesthetic had no influence on PONV frequency (9.3%, 11.2%, and 10.8% after isoflurane, desflurane, and sevoflurane, respectively; P = 0.8) or its severity (numerical rating scale, 4.5 +/- 2.0, 4.4 +/- 2.4, and 4.2 +/- 2.1; P = 0.9). Patients who received isoflurane experienced fewer early events but had a late peak of PONV frequency (P = 0.031). For every 10 minutes by which the total duration of the anesthesia exceeded the net time between incision and suture, the risk of PONV increased by a factor of 1.36 (95% confidence interval, 1.15-1.61; P < 0.001). CONCLUSIONS: There is no difference between the three inhalation anesthetics currently used with regard to frequency or severity of postoperative nausea, vomiting, or both.     

PONV: a problem of inhalational anaesthesia?

Even nowadays every third or fourth patient suffers from postoperative nausea and vomiting (PONV) after general anaesthesia with volatile anaesthetics. There is now strong evidence that volatile anaesthetics are emetogenic and that there are no meaningful differences between halothane, enflurane, isoflurane, sevoflurane, and desflurane in this respect. However, when propofol is substituted for volatile anaesthetics the risk for PONV is reduced by only about one fifth, indicating that there are other even more important causes for PONV following general anaesthesia. A main causative factor might be the use of perioperative opioids, but their impact--relative to other factors including volatile anaesthetics--has never been quantified. Patient-specific risk factors have also been shown to be clinically relevant; they are therefore included in the calculation of simplified risk scores that allow prediction of a patient's risk independent of the type of surgery. Although controversial, the well-known different incidences following certain types of surgery are most likely caused by patient-specific and anaesthesia-related risk factors. There is a common consensus that prophylaxis with anti-emetic strategies is rarely justified when the risk of PONV is low, while it is warranted in case of imminent medical risk associated with vomiting or in a patient with a high risk for PONV. A recently published large multicentre trial of factorial design, IMPACT, has demonstrated that various anti-emetic strategies are associated with a very similar and constant relative reduction rate of about 25-30% and that the main predictor for the efficacy of prophylaxis is the patient's risk for PONV. Interestingly, all anti-emetics (dexamethasone, droperidol and ondansetron) work independently, so that their combined benefit can be derived directly from the single effects. The effectiveness of the anti-emetics was also independent of a variety of risk factors, including volatile anaesthetics. This means that any anti-emetic prophylaxis for PONV induced by volatile anaesthetics is equally effective. Of course, the most logical approach for prevention would be the omission of volatile anaesthetics and nitrous oxide using a total intravenous anaesthesia with propofol. However, since volatile anaesthetics are probably not the most important risk factors, it might be even better--if appropriate--to avoid general anaesthesia by using a regional, opioid-free anaesthesia if PONV is a serious problem.     

Isoflurane, desflurane and sevoflurane for carotid endarterectomy

After carotid endarterectomy under general anaesthesia, the rapid elimination of desflurane and sevoflurane may allow earlier postoperative neurological assessment than after the use of isoflurane. However, desflurane may be associated with tachycardia and hypertension and may therefore increase cardiovascular risk. We investigated haemodynamic and recovery characteristics in patients scheduled for carotid endarterectomy who were anaesthetised with isoflurane, sevoflurane or desflurane. No significant peri-operative differences were noted in cardiac index or ST segment analysis. The times to extubation, movement on command and consciousness were shorter after desflurane and sevoflurane than after isoflurane anaesthesia. Postoperative pain, nausea, vomiting and shivering were similar in the three study groups.     

A review of recovery from sevoflurane anaesthesia: comparisons with isoflurane and propofol including meta-analysis

BACKGROUND: Sevoflurane has a lower blood:gas partition coefficient than isoflurane and thus should be associated with a more rapid recovery from anaesthesia. METHODS: A review and meta-analysis were employed to examine the recovery profiles of adult patients following anaesthesia, comparing sevoflurane to isoflurane and sevoflurane to propofol. RESULTS: There were significant differences in times to several recovery events that favoured sevoflurane to isoflurane anaesthesia, including time to emergence, response to commands, extubation, and orientation. Likewise, there were significant differences in times to the same recovery events following anaesthesia with sevoflurane versus propofol. There were no differences in time to recovery room discharge when comparing sevoflurane to isoflurane or propofol. CONCLUSION: The observed differences between sevoflurane and isoflurane or propofol anaesthesia support the postulate that the use of sevoflurane is associated with a more rapid recovery from anaesthesia than either isoflurane or propofol.     

Comparison of recovery after intermediate duration of anaesthesia with sevoflurane and isoflurane

BACKGROUND: The purpose of this study was to compare recovery from anaesthesia after sevoflurane and isoflurane were administered to children for more than 90 min. METHODS: After parental informed consent and ethical committee approval, children aged between 2 months and 6 years, ASA I or II, were randomly allocated to sevoflurane (n=20) or isoflurane (n=20) groups. Halogenated agents were discontinued following skin closure and patients were ventilated mechanically with 100% oxygen until minimum alveolar concentration (MAC) values awake were obtained (endtidal concentrations 0.6 MAC for sevoflurane and 0.4 MAC for isoflurane). Effective perioperative analgesia was provided by a caudal block. RESULTS: The mean (+/- SD) duration of anaesthesia was 132 +/- 38 min and 139 +/- 49 min for sevoflurane and isoflurane, respectively. Early recovery occurred sooner in the isoflurane group (time to extubation was 16 +/- 7 min and 11 +/- 5 min, P<0.01; Aldrete's score at 0 min was 5.5 +/- 1.5 and 7.4 +/- 1.8, P<0.001, respectively). But the time to be fit for discharge from recovery room was similar at 136 +/- 18 min and 140 +/- 20 min, respectively. CONCLUSIONS: After intermediate duration of anaesthesia administered to children for up to 90 min, isoflurane and sevoflurane allow recovery after approximatively the same lapse of time.     

Cost-effectiveness and high patient satisfaction in the elderly: sevoflurane versus propofol anaesthesia

BACKGROUND AND OBJECTIVE: The use of propofol compared with isoflurane is associated with improved patient comfort and decreased costs. However, as the cost saving, the quicker recovery time and patient comfort may not be evident if sevoflurane is substituted for isoflurane; these two anaesthetic agents were analysed in elderly patients. METHODS: In a prospective randomized study, 96 patients undergoing elective ophthalmic surgery received either total intravenous anaesthesia with propofol (Group P), propofol for induction and sevoflurane for maintenance (Group P/S) or sevoflurane for inhalation induction and maintenance (Group S). Analyses focussed on haemodynamics, the quality of recovery, and the costs for the anaesthetic and the entire procedure. RESULTS: Bradycardia or hypotension, mainly registered in Groups P and P/S, did not influence patients' recovery. In Group S, postoperative nausea and vomiting occurred frequently, and 50% of patients complained of discomfort during induction. In Group P/S, the costs for anaesthetics and total costs were lower than those in Groups P and S. CONCLUSIONS: Propofol- and sevoflurane-based maintenance of anaesthesia were similar with regard to patient comfort and recovery in the elderly. Cost analysis revealed that it was less expensive to use propofol for induction and sevoflurane for maintenance than to use either propofol or sevoflurane as sole agents for anaesthesia.     

Low flow and economics of inhalational anaesthesia

Even when anaesthesia does not represent a major part of the expense of a given surgical operation, reducing costs is not negligible because the large number of patients passing through a department of anaesthesia accounts for a huge annual budget. Volatile anaesthetics contribute 20% of the drug expenses in anaesthesia, coming just behind the myorelaxants; however, the cost of halogenated agents has potential for savings because a significant part of the delivered amount is wasted when a non- or partial-rebreathing system is used. The cost of inhaled agents is related to more than the amount taken up; it also depends on their market prices, their relative potencies, the amount of vapour released per millilitre of liquid, and last but not least the fresh-gas flow rate (FGF) delivered to the vaporizer--the most important factor determining the cost of anaesthesia. Poorly soluble agents like desflurane and sevoflurane facilitate the control of low-flow anaesthesia and reduce the duration of temporary high-flow phases to rapidly wash in or adjust the circuit gas concentrations. Modelling low-flow or minimal-flow anaesthesia will help anaesthetists to understand the kinetics of inhaled agents in those circumstances and to design their own clinical protocols. The monitoring facilities present on modern anaesthesia machines should convince clinicians that low- or even minimal-flow anaesthesia would not jeopardize the safety of their patients. Cost containment requires primarily a decrease in FGFs, but it may also be influenced by a rational use of the available halogenated agents. Isoflurane, the cheapest generic agent, might be advantageous for maintenance of anaesthesia of less than 3 hours. Sevoflurane is the agent of choice for inhalational induction and might also be used for maintenance. Desflurane might be preferred for long anaesthetics where rapid recovery will generate savings in the PACU.     

七氟醚、异氟醚和地氟醚对神经外科手术患者经颅电刺激运动诱发电位的影响

目的 比较七氟醚、异氟醚和地氟醚对神经外科手术患者经颅电刺激运动诱发电位(MEPs)的影响.方法 择期行神经外科手术患者60例,年龄18～64岁,ASA分级Ⅰ或Ⅱ级.随机分为3组(n=20):七氟醚组、异氟醚组和地氟醚组.监测BIS值和经颅电刺激MEPs.调节七氟醚、异氟醚和地氟醚吸入浓度,使其呼气末浓度分别达到0.50、0.75、1.00和1.30 MAC,每一浓度均维持15 min,视为稳态呼气末浓度.于给予吸入麻醉药前(基础状态)和达到各稳态呼气末浓度(T1-4)时,记录MEPs的波幅和潜伏期以及BIS值.记录MEPs波形记录失败情况.结果 与七氟醚组和异氟醚组比较,地氟醚组T1.2时波幅和BIS值降低,T1-4时潜伏期延长(P＜0.05);七氟醚组和异氟醚组各指标比较差异无统计学意义(P＞0.05).七氟醚组、异氟醚和地氟醚组基础状态、T1、T2时的记录失败率均为0;T3时记录失败率分别为0、5%和20%,三组比较差异无统计学意义(P＞0.05);T4时记录失败率分别为5%、20%和45%,与七氟醚组和异氟醚组比较,地氟醚组记录失败率升高(P＜0.05);七氟醚组和异氟醚组比较差异无统计学意义(P＞0.05).结论 地氟醚对神经外科手术患者经颅电刺激MEPs的抑制作用强于七氟醚和异氟醚.术中行MEPs监测时,七氟醚和异氟醚适宜的呼气末浓度为1.00 MAC,地氟醚为0.75～1.00 MAC.     

Ökonomische Aspekte beim Einsatz moderner Inhalationsanästhetika am Beispiel des Sevofluran

The economic impact of the new German health care laws requires an awareness of cost-effectiveness when using newer drugs. The main goal in patient care, i.e., effective treatment, must be achieved by the rational use of restricted resources at a maximum degree of effectiveness. Economic aspects of the new inhalational anaesthetics such as sevoflurane are discussed in this article. The cost of inhalational anaesthetic agents accounts for up to 5% of all the running expenses of an anaesthesia department. The consumption and cost of an inhalational agent depend on fresh gas flow, vapour setting, and duration of anaesthesia. Comparing the cost for 1 MAC-h of anaesthesia, desflurane is more expensive at current market prices than sevoflurane and isoflurane. However, at low or minimal fresh-gas flows, the price for one MAC-h is almost the same for these volatile anaesthetics. Total intravenous anaesthesia using propofol is even more expensive, partly due to wastage, i.e., opened ampoules with a remainder of propofol that has to be discarded after each case. When choosing an anaesthetic agent, the price of 1?ml liquid anaesthetic is an important factor. However, the overall cost-effectiveness analysis must balance the cost of the agent with its pharmacodynamic advantages such as more rapid recovery from anaesthesia. Furthermore, the indirect costs of side effects have to be taken into account. For example, nausea and vomiting lead to a prolonged stay in the recovery room after anaesthesia for outpatient surgery, which in turn incurs additional costs for antiemetic drugs and the extra time for nursing care. Therefore, a lower incidence of nausea and vomiting and a more rapid recovery from anaesthesia leading to earlier discharge from the recovery room may compensate for the higher price. Volatile agents account for up to 1% of the total intraoperative costs. In analysing the costs of 1?h of anaesthesia, other products such as plasma substitutes and blood products account for a much higher proportion than anaesthetic agents, and reductions or increases in costs pertaining to these products have a bigger impact on overall costs than do volatile anaesthetics. We conclude that volatile anaesthetics account for only a minor portion of the anaesthesia department budget and the cost of anaesthesia delivery. The higher market price of the new agents may be compensated for by the economic impact of fewer side effects and a shorter post-anaesthesia stay in the hospital. In analysing data for sevoflurane, this agent may be cost-effective, for example, for outpatient anaesthesia.     

New agents, the circle system and short procedures

Sevoflurane, desflurane and isoflurane were compared using a circle system in 97 patients undergoing short surgical procedures. Using initial high flows, the time intervals to equilibration between inspired and end-expired agent concentrations were measured; equilibration was defined as F _E/ F ₁ =0.8. The mean (SD) times obtained for sevoflurane, desflurane and isoflurane were 8.2 (2.1) min, 3.8 (0.7) min and 19.7 (6.5) min, respectively. These times were significantly different from each other (p <0.0001). After equilibration total flows were reduced to 500 ml.min⁻¹; at these flows the initial decline in end-expired agent concentration was minimal with desflurane, intermediate with sevoflurane and greatest with isoflurane. Both desflurane and sevoflurane are appropriate for efficient use of the circle system during short anaesthetics.