Economic Evaluation of Pharmacologic Pre- and Postconditioning With Sevoflurane Compared With Total Intravenous Anesthesia in Liver Surgery: A Cost Analysis.

BACKGROUND: Pharmacologic pre- and postconditioning with sevoflurane compared with total IV anesthesia in patients undergoing liver surgery reduced complication rates as shown in 2 recent randomized controlled trials. However, the potential health economic consequences of these different anesthesia regimens have not yet been assessed. METHODS: An expostcost analysis of these 2 trials in 129 patients treated between 2006 and 2010 was performed. We analyzed direct medical costs for in-hospital stay and compared pharmacologic pre- and postconditioning with sevoflurane (intervention) with total IV anesthesia (control) from the perspective of a Swiss university hospital. Year 2015 costs, converted to US dollars, were derived from hospital cost accounting data and compared with a multivariable regression analysis adjusting for relevant covariables. Costs with negative prefix indicate savings and costs with positive prefix represent higher spending in our analysis. RESULTS: Treatment-related costs per patient showed a nonsignificant change by -12,697 US dollars (95% confidence interval [CI], 10,956 to -36,352; P = .29) with preconditioning and by -6139 US dollars (95% CI, 6723 to -19,000; P = .35) with postconditioning compared with the control group. Results were robust in our sensitivity analysis. For both procedures (control and intervention) together, major complications led to a significant increase in costs by 86,018 US dollars (95% CI, 13,839-158,198; P = .02) per patient compared with patients with no major complications. CONCLUSIONS: In this cost analysis, reduced in-hospital costs by pharmacologic conditioning with sevoflurane in patients undergoing liver surgery are suggested. This possible difference in costs compared with total IV anesthesia is the result of reduced complication rates with pharmacologic conditioning, because major complications have significant cost implications.

COMPARISON OF ISOFLURANE AND SEVOFLURANE FOR SHORT-TERM ANESTHESIA IN MEERKATS (SURICATA SURICATTA)-ARE THERE BENEFITS THAT OUTWEIGH COSTS?

Meerkats ( Suricata suricatta ) are routinely anesthetized with isoflurane in zoo and field settings. Twenty healthy adult meerkats of mixed age and sex held in the Zoological Society of London's collection were anesthetized with 4% isoflurane by face mask for routine health examinations. The procedure was repeated 5 mo later in the same group of animals utilizing sevoflurane at 5% for induction, and again 3 mo later with sevoflurane at 6.5% for induction to approximate equipotency with isoflurane. The speed and quality of induction and recovery were compared between the two volatile anesthetic agents. There was no statistically significant difference in the speed of induction across any of the anesthetic regimes. There was a significant difference in recovery times between isoflurane and 6.5% sevoflurane (427 ± 218 and 253 ± 65 sec, respectively [mean ± SD]). Under the conditions of this study, sevoflurane at 6.5% induction dose resulted in better quality induction and recovery than sevoflurane at 5% induction or isoflurane. The mean heart and respiratory rates during anesthesia were higher using 5% sevoflurane for induction but there was no significant difference in either rate between isoflurane and sevoflurane used at a 6.5% induction dose. This study suggests that sevoflurane at a dose of 6.5% for induction and 4% for maintenance is a safe and effective anesthetic agent in healthy adult meerkats. Rapid return to normal behavior after anesthesia is important in all zoo species but particularly so in animals with a complex social and hierarchical structure such as meerkats. For this species, the advantage afforded by the speed of recovery with sevoflurane may offset the cost in certain circumstances.

Economic and Environmental Considerations During Low Fresh Gas Flow Volatile Agent Administration After Change to a Nonreactive Carbon Dioxide Absorbent.

BACKGROUND: Reducing fresh gas flow (FGF) during general anesthesia reduces costs by decreasing the consumption of volatile anesthetics and attenuates their contribution to greenhouse gas pollution of the environment. The sevoflurane FGF recommendations in the Food and Drug Administration package insert relate to concern over potential toxicity from accumulation in the breathing circuit of compound A, a by-product of the reaction of the volatile agent with legacy carbon dioxide absorbents containing strong alkali such as sodium or potassium hydroxide. Newer, nonreactive absorbents do not produce compound A, making such restrictions moot. We evaluated 4 hypotheses for sevoflurane comparing intervals before and after converting from a legacy absorbent (soda lime) to a nonreactive absorbent (Litholyme): (1) intraoperative FGF would be reduced; (2) sevoflurane consumption per minute of volatile agent administration would be reduced; (3) cost savings due to reduced sevoflurane consumption would (modestly) exceed the incremental cost of the premium absorbent; and (4) residual wastage in discarded sevoflurane bottles would be <1%. METHODS: Inspired carbon dioxide (PICO2), expired carbon dioxide, oxygen, air, and nitrous oxide FGF, inspired volatile agent concentrations (FiAgent), and liquid volatile agent consumption were extracted from our anesthesia information management system for 8 4 week intervals before and after the absorbent conversion. Anesthesia providers were notified by e-mail and announcements at Grand Rounds about the impending change and were encouraged to reduce their average intraoperative sevoflurane FGF to 1.25 L/min. Personalized e-mail reports were sent every 4 weeks throughout the study period regarding the average intraoperative FGF (i.e., from surgery begin to surgery end) for each agent. Batch means methods were used to compare FGF, volatile agent consumption, net cost savings, and residual sevoflurane left in bottles to be discarded in the trash after filling vaporizers. The time from reaching a PICO2 = 3 mm Hg for 3 minutes until agent exhaustion (PICO2 = 5 mm Hg for 5 minutes) was evaluated. RESULTS: A total of N = 20,235 cases were analyzed (80.2% sevoflurane, 15.1% desflurane, and 4.7% isoflurane). Intraoperative FGF was reduced for cases in which sevoflurane was administered by 435 mL/min (95% confidence interval [CI], 391 to 479 mL/min; P < 10). Hypothesis 1 was accepted. Sevoflurane consumption per minute of administration decreased by 0.039 mL/min (95% CI, 0.029 to 0.049 mL/min; P < 10) after the change to the nonreactive absorbent. Hypothesis 2 was accepted. The difference in mean cost for the sum of the sevoflurane and absorbent purchases for each of the 10 4-week intervals before and after the absorbent switch was -$293 per 4-week interval (95% CI, -$2853 to $2266; P = 0.81). Hypothesis 3 was rejected. The average amount of residual sevoflurane per bottle was 0.67 ± 0.06 mL (95% CI, 0.54 to 0.81 mL per bottle; P < 10 vs 2.5 mL). Hypothesis 4 was accepted. Once the PICO2 reached 3 mm Hg for at least 3 consecutive minutes, the absorbent became exhausted within 95 minutes in most (i.e., >50%) canisters. CONCLUSIONS: We showed that an anesthesia department can transition to a premium, nonreactive carbon dioxide absorbent in a manner that is at least cost neutral by reducing FGF below the lower flow limits recommended in the sevoflurane package insert. This was achieved, in part, by electronically monitoring PICO2, automatically notifying the anesthesia technicians when to change the absorbent, and by providing personalized feedback via e-mail to the anesthesia providers.

Calculation of volatile anaesthetics consumption from agent concentration and fresh gas flow.

BACKGROUND: The assessment of volatile agents' consumption can be performed by weighing vapourisers before and after use. This method is technically demanding and unavailable for retrospective analysis of anaesthesia records. Therefore, a method based on calculations from fresh gas flow and agent concentration is presented here. METHODS: The presented calculation method herein enables a precise estimation of volatile agent consumption when average fresh gas flows and volatile agent concentrations are known. A pre-condition for these calculations is the knowledge of the vapour amount deriving from 1 ml fluid volatile agent. The necessary formulas for these calculations and an example for a sevoflurane anaesthesia are presented. RESULTS: The amount of volatile agent vapour deriving from 1 ml of fluid agent are for halothane 229 ml, isoflurane 195 ml, sevoflurane 184 m, and desflurane 210 ml. The constant for sevoflurane is used in a fictitious clinical case to exemplify the calculation of its consumption in daily routine resulting in a total expenditure of 23.6 ml liquid agent. CONCLUSIONS: By application of the presented specific volatile agent constants and equations, it becomes easy to calculate volatile agent consumption if the fresh gas flows and the resulting inhaled concentration of the volatile agent are known. By this method, it is possible to extract data about volatile agent consumption both ways: (1) retrospectively from sufficiently detailed and accurate anaesthesia recordings, as well as (2) by application of this method in a prospective setting. Therefore, this method is a valuable contribution to perform pharmacoeconomical surveys.

Sevoflurane induction procedure: cost comparison between fixed 8% versus incremental techniques in pediatric patients.

This study compared 2 well-accepted and safe methods of pediatric inhalation induction using sevoflurane. Incremental and fixed 8% induction methods were evaluated for economic outcomes by comparing the amount of liquid sevoflurane consumed. We also tried to establish the relation between cost of induction and demographic parameters in both groups. One hundred pediatric patients scheduled for ophthalmologic examination under anesthesia were randomly divided into 2 equal groups. The amount of sevoflurane consumed in both groups was computed using the Dion method. Although the time to loss of consciousness was significantly lower using the 8% method (75.98 vs 135 seconds), the liquid sevoflurane consumption using the incremental method (2.25 mL) was almost half that of the fixed 8% method (4.46 mL). The overall procedural cost of induction (loss of consciousness plus intravenous cannulation and insertion of a laryngeal mask airway) was also almost double using the fixed 8% method. Use of the incremental method preferably over the fixed 8% method could save almost $18 US for each procedure. The volume of sevoflurane consumed during anesthesia induction was found to be independent of age, weight, or sex of pediatric patients. Both induction methods proved to be equally safe and acceptable to the patients.

Halothane: how should it be used in a developing country?

The anaesthetic agent halothane is still widely used in developing countries including the Islamic Republic of Iran because of its low price. Because of halothane-induced hepatitis, a rare complication, it has been replaced by other inhalation anaesthetics in Western countries; it has been suggested by some Iranian professionals that the Islamic Republic of Iran should do the same. We evaluated various dimensions of this replacement through a literature review to assess the incidence of halothane-induced hepatitis and costs of anaesthetics in the country. We also conducted a questionnaire survey of 30 anaesthesiology/gastroenterology experts about their views on the subject. The results indicate that the incidence of halothane hepatitis in the Islamic Republic of Iran is very low and could mostly be avoided by strict adherence to guidelines. Complete withdrawal of halothane in the Islamic Republic of Iran might not be appropriate at present. Comprehensive cost-effectiveness studies are needed before a decision is made on complete replacement of halothane with other anaesthetics.

Cuffed endotracheal tubes in children reduce sevoflurane and medical gas consumption and related costs.

BACKGROUND: This study aims to evaluate sevoflurane and anaesthetic gas consumption using uncuffed vs. cuffed endotracheal tubes (ETT) in paediatric surgical patients. METHODS: Uncuffed or cuffed ETT were used in paediatric patients (newborn to 5 years) undergoing elective surgery in a randomized order. Duration of assessment, lowest possible fresh gas flow (minimal allowed FGF: 0.5 l/min) and sevoflurane concentrations used were recorded. Consumption and costs for sevoflurane and medical gases were calculated. RESULTS: Seventy children (35 uncuffed ETT/35 cuffed ETT), aged 1.73 (0.01-4.80) years, were enrolled. No significant differences in patient characteristics, study period and sevoflurane concentrations used were found between the two groups. Lowest possible FGF was significantly lower in the cuffed ETT group [1.0 (0.5-1.0) l/min] than in the uncuffed ETT group [2.0 (0.5-4.3) l/min], P<0.001. Sevoflurane consumption per patient was 16.1 (6.4-82.8) ml in the uncuffed ETT group and 6.2 (1.1-14.9) ml in the cuffed ETT group, P=0.003. Medical gas consumption was 129 (53-552) l in the uncuffed ETT group vs. 46 (9-149) l in the cuffed ETT group, P<0.001. The total costs for sevoflurane and medical gases were 13.4 (6.0-67.3)euro/patient in the uncuffed ETT group and 5.2 (1.0-12.5)euro/patient in the cuffed ETT group, P<0.001. CONCLUSIONS: The use of cuffed ETT in children significantly reduced the costs of sevoflurane and medical gas consumption during anaesthesia. Increased costs for cuffed compared with uncuffed ETT were completely compensated by a reduction in sevoflurane and medical gas consumption.

Low fresh gas flow balanced anesthesia versus target controlled intravenous infusion anesthesia in laparoscopic cholecystectomy: a cost-minimization analysis.

BACKGROUND: Laparoscopic surgery is widely recognized as a well-tolerated and effective method for cholecystectomy. It is also considered cost saving because it has been associated with a decreased hospital length of stay. Variables that might lead to increased costs in laparoscopic surgery are the technique and drugs used in anesthesia. OBJECTIVE: The goal of this study was to compare the costs of 2 anesthetic techniques used in laparoscopic cholecystectomy (LC)--balanced versus IV anesthesia--from the standpoint of an outpatient surgical department, with a time horizon of 1 year. METHODS: Patients scheduled to undergo elective LC were enrolled in this prospective case study. Patients were randomly allocated to receive balanced anesthesia, administered as low fresh gas flow (LFGF) with inhalational sevoflurane and IV sufentanil in a target controlled infusion (LFGF SS group), or IV anesthesia, administered as IV propofol/sufentanil in a target controlled infusion (TCI group). We used a microcosting procedure to measure health care resource utilization in individual patients to detect treatment differences. The costs of medications used for the induction and maintenance of anesthesia during surgery were considered for LFGF SS and TCI. Other end points included duration of anesthesia; mean times to early emergence, tracheal extubation, orientation, and postanesthesia discharge (PAD); pain intensity before first analgesia; number of analgesics required in the first 24 hours after surgery; and prevalences of nausea, vomiting, and agitation. RESULTS: A total of 60 patients were included in this analysis (male/female ratios in the LFGF SS and TCI groups: 11/19 and 12/18, respectively; mean [SD] ages, 48 [7.9] and 47 [8.6] years; and mean [SD] body mass indexes, 26 [2.0] and 26 [3.0] kg/m2). The costs of anesthetics were significantly lower with LFGF SS compared with TCI (euro17.40 [euro2.66] vs euro22.01 [euro2.50] [2006 euros]). Times to early emergence and tracheal extubation were significantly shorter with LFGF SS than TCI (5.97 [1.16] vs 7.73 [1.48] minutes and 7.57 [1.07] vs 8.87 [1.45] minutes, respectively). There were no significant between-group differences in mean duration of anesthesia; times to orientation and PAD; pain intensity before first analgesia; number of analgesics required in the first 24 hours; or prevalences of nausea, vomiting, and agitation. Because no clinically significant differences in the anesthetic results were observed, a cost-minimization analysis was conducted and found that using LFGF SS, the outpatient surgical department could realize a budget savings of euro454 per 100 patients. For the nearly 1000 expected patients per year, the savings for the department was calculated as euro4540. CONCLUSION: The results from this cost analysis in these patients who underwent elective LC suggest that the use of sevoflurane through the LFGF technique would be cost saving in this outpatient surgical department.

Does monitoring bispectral index or spectral entropy reduce sevoflurane use?

A decrease in volatile anesthetic consumption has been demonstrated using bispectral index (BIS), whereas data concerning spectral entropy are lacking. One hundred and forty adult patients scheduled for surgical procedures lasting more than 1 h were prospectively randomized to receive an anesthetic controlled either by BIS or by spectral entropy or solely by clinical variables. Anesthesia was induced with propofol and sufentanil. Sufentanil was infused continuously thereafter. Sevoflurane was administered in 1 L/min O2/N2O. The sevoflurane concentration was adjusted according to conventional clinical variables in the standard practice group, whereas the 40-60 interval was applied for the BIS and spectral entropy-guided groups. The sevoflurane vaporizer was weighed before and after anesthesia, and consumption was calculated. Groups were comparable for demographic data except for weight (heavier in the spectral entropy-guided group, P < 0.05). Compared with standard practice, patients with BIS or spectral entropy monitoring required 29% less sevoflurane (normalized sevoflurane consumption to the weights of the patients and to the durations of anesthesia; both P < 0.03) and a similar sufentanil dose. An unintended improvement in the standard practice group (positive bias) was observed. In conclusion, BIS and spectral entropy monitoring have the same sparing effect of sevoflurane.

Cost minimisation and cost effectiveness in anaesthesia for total hip replacement surgery, in Belgium? A study comparing three general anaesthesia techniques.

The aim of the prospective randomised study is to compare the cost effectiveness of three general anaesthesia techniques for total hip replacement surgery and the cost minimisation by use of anaesthetics. For induction propofol was used in the three techniques. For maintenance, we used desflurane, or sevoflurane, or propofol. There was no significant difference in consumption of drugs for pain treatment, treatment of nausea and vomiting or cost of hospital stay or total cost for pharmacy. In terms of cost-effectiveness we can consider that the three techniques are similar. The cost of an i.v. technique was always higher than inhaled anaesthetics. The major cost in anaesthesia is the fee for the anaesthesiologist. But all in, the cost of anaesthesia was only 15.1% of the total cost of the procedure. Cost of inhaled or i.v. anaesthetics was 0.55% to 1.0% of the total cost. There was a discrepancy between the measured consumption of inhaled anaesthetics and the consumption (and cost) on the invoice. Cost minimisation based on anaesthetic medication is ridiculously by small considering the total cost of the procedure.

Irrigation with Liquid Sevoflurane and Healing of a Postoperative, Recurrent Epidural Infection: A Potential Cost-Saving Alternative.

BACKGROUND: The general inhalation anesthetic sevoflurane can be used for the topical treatment of complicated wounds. It is applied in liquid form and may be used to irrigate the inside of cavities. Sevoflurane also exhibits in vitro antimicrobial activity. Therefore, sevoflurane may be used as an alternative to typical antibiotic or surgical treatment of complicated, localized infections. CASE DESCRIPTION: The case of a 61-year-old male patient who suffered a cranioencephalic trauma 18 years previously is presented. The patient underwent surgeries related to the trauma on numerous occasions. To date, he has suffered various recurrent epidural abscesses, which have been treated with surgical cleaning and antibiotic treatment. In the most recent episode, he presented a frontal epidural abscess 25 mm in diameter with fistulization of the skin. The patient gave written informed consent to be treated with sevoflurane irrigation, and the Pharmacy Service authorized the off-label use. Sevoflurane was applied via a catheter placed inside the cavity during weekly outpatient procedures. The procedures began 8 weeks after the clinically and radiologically verified recovery of the abscess. By avoiding surgery and the associated hospital admission, this novel alternative may prevent patient morbidity and, furthermore, may produce important economic savings. CONCLUSIONS: The treatment of complicated wounds with liquid sevoflurane may be an effective and economically efficient clinical alternative for some patients.

Inhalation anesthesiology and volatile liquid anesthetics: focus on isoflurane, desflurane, and sevoflurane.

Clinical pharmacists rarely are involved in the selection and dosing of anesthetic agents. However, when practicing evidence-based medicine in a cost-conscious health care system, optimizing drug therapy is imperative in all areas. Thus, we provide general information on anesthesiology, including the different types of breathing systems and the components of anesthesia machines. Modern inhalation anesthetics that are predominantly used in clinical practice include one gas--nitrous oxide--and new volatile liquid agents--isoflurane, desflurane, and sevoflurane. Desflurane and sevoflurane are the low-soluble inhalation anesthetics, and they offer some clinical advantages over isoflurane, such as fast induction and faster recovery with long procedures. However, efficient use of isoflurane can match the speed of induction and recovery of the other agents in certain cases. In addition, the patient characteristics, duration and type of procedure, type of breathing system, and efficiency in monitoring must be considered when selecting the most optimal therapy for each patient. Maximizing the clinical advantages of these agents while minimizing the waste of an institution's operating room and pharmacy budget requires an understanding of the characteristics, pharmacokinetics, and pharmacodynamics of these anesthetic agents and the collaborated effort from both the anesthesia and pharmacy departments. An anesthetic agent algorithm is provided as a sample decision-process tree for selecting among isoflurane, desflurane, and sevoflurane.

A simple intervention to reduce the anesthetic pharmacy budget; the effect of price list stickers placed on vaporizers.

STUDY OBJECTIVE: The study objective is to investigate the effects of a simple price list sticker placed on vaporizers on anesthetic use and costs. The price list only showed the cost per hour of the annually most expensive drugs, which had a low-cost alternative. DESIGN: The design is a prospective database study with historical controls. SETTING: The setting is at operating rooms. PATIENTS: All patients are undergoing a surgical procedure under anesthesia in both study periods, except cardiothoracic and day care patients. INTERVENTIONS: The intervention is application of a price list sticker on the vaporizers. MEASUREMENTS: Monthly cost and amount of anesthetic agents used during the 9 months before and after the intervention. MAIN RESULTS: After application of the price stickers, the use of both the annually most expensive agents and the anesthetic budget decreased substantially. Most notable was a decrease of 28% in the use of sevoflurane. CONCLUSIONS: Price sticker on vaporizers may be an effective, simple, and cheap method to reduce anesthetic costs.

Inhalation versus total intravenous anesthesia for lumbar disc herniation: comparison of hemodynamic effects, recovery characteristics, and cost.

The clinical effects, recovery characteristics, and costs of total intravenous anesthesia (TIVA), sevoflurane, and isoflurane anesthesia have been measured in various out-patient operations, but have not been evaluated in patients undergoing laminectomy or discectomy. In the current study, the authors assessed the hemodynamic characteristics, recovery, and cost analyzes after laminectomy and discectomy operations, comparing TIVA, sevoflurane, and isoflurane anesthesia. Sixty American Society of Anesthesiologists I and II patients were randomly divided into three groups, each consisting of 20 patients. Group I received propofol-alfentanil, Group 2 received sevoflurane-N2O, and Group 3 received isoflurane-N2O. At the end of surgery, the anesthetics were discontinued, and recovery from anesthesia was assessed by measuring the time until spontaneous eye opening and the time until response to verbal commands. The drug and delivery costs were calculated in United States dollars. No significant differences were found in the demographic data. Heart rate and mean arterial pressure decreased significantly after induction of anesthesia in the TIVA group, compared to the two other groups ( P < .05 for both comparisons). The fastest recovery was seen in the TIVA group. Incidences of postoperative nausea, vomiting, and pain were significantly reduced after TIVA ( P < .05 for both comparisons). Thus, TIVA patients required fewer additional drugs and showed the lowest additional costs in the post-anesthesia care unit. However, the total cost was significantly higher in the TIVA group than in the sevoflurane and isoflurane groups (52.73 dollars, 29.99 dollars, and 24.14 dollars, respectively) ( P < .05). Total intravenous anesthesia was associated with the highest intraoperative cost but provided the most rapid recovery from anesthesia, and the least frequent postoperative side effects.

Cost analysis of xenon anesthesia: a comparison with nitrous oxide-isoflurane and nitrous oxide-sevoflurane anesthesia.

STUDY OBJECTIVE: To determine the cost of xenon (Xe) anesthesia in relation to the anesthetic duration by conducting a cost analysis of this relatively expensive inhaled anesthetic. DESIGN: Cost analysis based on the literature on Xe anesthesia. SETTING: Anesthetic simulation based on data obtained in the operating rooms at a university hospital. PATIENTS: A 40-year-old, ASA physical status I adult patient model weighing 70 kg, undergoing elective minor surgery with endotracheal intubation and mechanical ventilation. INTERVENTIONS: Anesthesia was given in the following four techniques: 1) closed-circuit technique with Xe; 2) closed-circuit technique with nitrous oxide (N2O)-isoflurane; 3) semi-closed technique with N2O-isoflurane; and 4) semi-closed technique with N2O-sevoflurane. MEASUREMENTS AND MAIN RESULTS: Cost of each anesthetic technique was compared in U.S. dollars. The cost of Xe anesthesia was consistently higher than that of N2O-isoflurane or N2O-sevoflurane (for 240-min anesthesia; $356 with Xe, $52 with closed-circuit N2O-isoflurane, $94 with semi-closed N2O-isoflurane, and $84 with semi-closed N2O-sevoflurane). The major cost of Xe anesthesia was a result of the cost of priming and flushing; the cost of Xe used for its anesthetic effects was comparable with the other semi-closed techniques after 240 minutes. CONCLUSIONS: For Xe to be widely used in routine anesthesia, the methods of minimizing the amount of Xe necessary for priming and flushing must be developed.

Sevoflurane-N2O versus propofol/isoflurane-N2O during elective surgery using the laryngeal mask airway in adults.

STUDY OBJECTIVES: To compare a sevoflurane-nitrous oxide (N2O) general anesthetic technique with a standard technique of propofol for induction, and isoflurane-N2O for maintenance. DESIGN: Prospective, randomized study. SETTING: University-affiliated tertiary-care hospital. PATIENTS: 62 adults undergoing elective surgery using the laryngeal mask airway (LMA). INTERVENTIONS: Patients received either the standard technique of propofol for induction and isoflurane-N2O for maintenance (controls) or sevoflurane-N2O for both induction and maintenance of general anesthesia. MEASUREMENTS: Induction and emergence times, heart rate, blood pressure, oxygen saturation, and end-tidal carbon dioxide were recorded. MAIN RESULTS: Time to loss of consciousness was faster after propofol (mean +/- SEM: 51 +/- 3 sec) than after sevoflurane-N2O (85 +/- 10 sec; p < 0.05). Ready for surgery times, were however, similar between groups (10 +/- 1 vs. 11 +/- 1 min, respectively). All patients in the control group had apnea after LMA insertion compared with 4 patients in the sevoflurane-N2O group (p < 0.05). Heart rate was lower 5 and 10 minutes after LMA insertion in the sevoflurane-N2O group (69 +/- 3 and 66 +/- 3 bpm) versus the control group (81 +/- 3 bpm and 74 +/- 3 bpm, p < 0.05). After cessation of anesthetic gases, there were no differences in time to LMA removal, eye opening, or exiting the operating room (OR) between the control group (7, 8, and 10 min) and sevoflurane-N2O groups (7, 8, and 12 min, respectively). The majority of patients in both groups (92% to 97%) rated their anesthetic experience as excellent or good. CONCLUSIONS: Sevoflurane-N2O and propofol provided comparable conditions for LMA insertion. Sevoflurane-N2O was not associated with a faster return of consciousness or faster time to exit the OR compared with isoflurane-N2O.

Concentrations and costs of a thirty second priming technique with sevoflurane using the circle circuit.

BACKGROUND: Priming the circuit for an application of inhalation agent depends on the time taken, the fresh gas flow (FGF) rate, the concentration setting of the agent on the vaporizer, and the priming technique. Based on previous studies, the priming time for a desirable concentration of sevoflurane varied between 30 seconds and 5 minutes. Remarkably, although the cost of priming with sevoflurane was lowest at 30 seconds, concentrations in the circuit were not clearly stated. The aim of this study was to test the success (and cost) of a 30-second priming technique to achieve a 4.5 per cent sevoflurane concentration in the circle circuit. METHOD: Analyses were done on 20 samplings. Each time the adjustable pressure-limiting (APL) valve on the assembly was closed, the 2-liter reservoir bag emptied and the patient end occluded. For 30 seconds, the circuit was filled with oxygen (8 L x min(-1)) and 8 per cent sevoflurane. The pressure in the circuit was kept constant at 10 mbar by partially releasing the excess gas at the patient end. After 30 seconds, the sevoflurane concentration at the patient end of the circuit was analyzed and the highest concentration recorded. The cost of the sevoflurane used was then calculated. RESULTS: The sevoflurane concentration in all of the samples was more than 4.5 per cent (mean 6.40%; SD 0.30%). The average amount of liquid sevoflurane used was 1.8 ml at a cost of 42.30 baht (0.9 US dollars). CONCLUSION: A 30-second priming technique was sufficient to achieve the required concentration of sevoflurane in the circle circuit thus reducing costs for gaseous induction.