Environmental and economic impact of using increased fresh gas flow to reduce carbon dioxide absorbent consumption in the absence of inhalational anaesthetics.

BACKGROUND: Increasing fresh gas flow (FGF) to a circle breathing system reduces carbon dioxide (CO2) absorbent consumption. We assessed the environmental and economic impacts of this trade-off between gas flow and absorbent consumption when no inhalational anaesthetic agent is used. METHODS: A test lung with fixed CO2 inflow was ventilated via a circle breathing system of an anaesthetic machine (Dräger Primus or GE Aisys CS2) using an FGF of 1, 2, 4, or 6 L min-1. We recorded the time to exhaustion of the CO2 absorbent canister, defined as when inspired partial pressure of CO2 exceeded 0.3 kPa. For each FGF, we calculated the economic costs and the environmental impact associated with the manufacture of the CO2 absorbent canister and the supply of medical air and oxygen. Environmental impact was measured in 100 yr global-warming potential, analysed using a life cycle assessment 'cradle to grave' approach. RESULTS: Increasing FGF from 1 to 6 L min-1 was associated with up to 93% reduction in the combined running cost with minimal net change to the 100 yr global-warming potential. Most of the reduction in cost occurred between 4 and 6 L min-1. Removing the CO2 absorbent from the circle system, and further increasing FGF to control CO2 rebreathing, afforded minimal further economic benefit, but more than doubled the global-warming potential. CONCLUSIONS: In the absence of inhalational anaesthetic agents, increasing FGF to 6 L min-1 reduces running cost compared with lower FGFs, with minimal impact to the environment.

Estimating the Impact of Carbon Dioxide Absorbent Performance Differences on Absorbent Cost During Low-Flow Anesthesia.

BACKGROUND: Reducing fresh gas flow when using a circle anesthesia circuit is the most effective strategy for reducing both inhaled anesthetic vapor cost and waste. As fresh gas flow is reduced, the amount of exhaled gas rebreathed increases, but the utilization of carbon dioxide absorbent increases as well. Reducing fresh gas flow may not make economic sense if the increased cost of absorbent utilization exceeds the reduced cost of anesthetic vapor. The primary objective of this study was to determine the minimum fresh gas flow at which absorbent costs do not exceed vapor savings. Another objective is to provide a qualitative insight into the factors that influence absorbent performance as fresh gas flow is reduced. METHODS: A mathematical model was developed to compare the vapor savings with the cost of carbon dioxide absorbent as a function of fresh gas flow. Parameters of the model include patient size, unit cost of vapor and carbon dioxide absorbent, and absorbent capacity and efficiency. Boundaries for fresh gas flow were based on oxygen consumption or a closed-circuit condition at the low end and minute ventilation to approximate an open-circuit condition at the high end. Carbon dioxide production was estimated from oxygen consumption assuming a respiratory quotient of 0.8. RESULTS: For desflurane, the cost of carbon dioxide absorbent did not exceed vapor savings until fresh gas flow was almost equal to closed-circuit conditions. For sevoflurane, as fresh gas flow is reduced, absorbent costs increase more slowly than vapor costs decrease so that total costs are still minimized for a closed circuit. Due to the low cost of isoflurane, even with the most effective absorbent, the rate of absorbent costs increase more rapidly than vapor savings as fresh gas flow is reduced, so that an open circuit is least expensive. The total cost of vapor and absorbent is still lowest for isoflurane when compared with the other agents. CONCLUSIONS: The relative costs of anesthetic vapor and carbon dioxide absorbent as fresh gas flow is reduced are dependent on choice of anesthetic vapor and performance of the carbon dioxide absorbent. Absorbent performance is determined by the product selected and strategy for replacement. Clinicians can maximize the performance of absorbents by replacing them based on the appearance of inspired carbon dioxide rather than the indicator. Even though absorbent costs exceed vapor savings as fresh gas flow is reduced, isoflurane is still the lowest cost choice for the environmentally sound practice of closed-circuit anesthesia.

Provider Education and Vaporizer Labeling Lead to Reduced Anesthetic Agent Purchasing With Cost Savings and Reduced Greenhouse Gas Emissions.

Anesthetic agents are known greenhouse gases with hundreds to thousands of times the global warming impact compared with carbon dioxide. We sought to mitigate the negative environmental and financial impacts of our practice in the perioperative setting through multidisciplinary staff engagement and provider education on flow rate reduction and volatile agent choice. These efforts led to a 64% per case reduction in carbon dioxide equivalent emissions (163 kg in Fiscal Year 2012, compared with 58 kg in Fiscal Year 2015), as well as a cost savings estimate of $25,000 per month.

Efficacy of Malignant Hyperthermia Association of the United States-Recommended Methods of Preparation for Malignant Hyperthermia-Susceptible Patients Using Dräger Zeus Anesthesia Workstations and Associated Costs.

BACKGROUND: The objective of this study was to assess the efficacy and cost of Malignant Hyperthermia Association of the United States-recommended methods for preparing Dräger Zeus anesthesia workstations (AWSs) for the malignant hyperthermia-susceptible patient. METHODS: We studied washout profiles of sevoflurane, isoflurane, and desflurane in 3 Zeus AWS following 3 preparation methods. AWS was primed with 1.2 minimum alveolar concentration anesthetic for 2 hours using 2 L/min fresh gas flow, 500 mL tidal volume, and 12/min respiratory rate. Two phases of washout were performed: high flow (10 L/min) until anesthetic concentration was <5 parts per million (ppm) for 20 minutes and then low flow (3 L/min) for 20 minutes to identify the rebound effect. Preparation methods are as follows: method 1 (M1), changing disposables (breathing circuit, soda lime, CO2 line, and water traps); method 2 (M2), M1 plus replacing the breathing system with an autoclaved one; and method 3 (M3), M1 plus mounting 2 activated charcoal filters on respiratory limbs. Primary outcomes are as follows: time to obtain anesthetic concentration <5 ppm in the high-flow phase, peak anesthetic concentrations in the low-flow phase, and for M3 only, peak anesthetic concentration after 70 minutes of low-flow phase, when activated charcoal filters are removed. Secondary outcomes are as follows: cost analysis of time and resources to obtain anesthetic concentration <5 ppm in each method and a vapor-free Zeus AWS. Sensitivity analyses were performed using alternative assumptions regarding the costs and the malignant hyperthermia-susceptible caseload per year. RESULTS: Primary outcomes were as follows: M3 instantaneously decreased anesthetic concentration to <1 ppm with minimal impact of low-flow phase. M1 (median, 88 minutes; 95% confidence interval [CI], 69-112 minutes) was greater than M2 (median, 11 minutes; 95% CI, 9-15 minutes). Means of peak rebound anesthetic concentrations in M1, M2, and M3 were 15, 6, and 1 ppm, respectively (P < .001). Anesthetic concentration increased 33-fold (95% CI, 21-50) after removing charcoal filters (from 0.7 to 20 ppm). The choice of anesthetic agents did not impact the results. Secondary outcomes were as follows: M3 was the lowest cost when the cost of lost operating room (OR) time due to washout was included, and M1 was the lowest cost when it was not included. When the cost of lost OR time due to washout was considered the estimated cost/case of M3 was US $360 (M1, US $2670; M2, US $969; and a "vapor-free" Zeus AWS was US $930). The OR time and equipment costs represent the largest differentiators among the methods. CONCLUSIONS: Institutions in which demand for OR time has exceeded capacity should consider M3, and institutions with surplus OR capacity should consider M1.

Comparison of low-fresh gas flow technique to standard technique of sevoflurane induction in children-A randomized controlled trial.

BACKGROUND: Although sevoflurane is preferred for inhalational induction in children, financial and environmental costs remain major limitations. The aim of this study was to determine if the use of low-fresh gas flow during inhalational induction with sevoflurane could significantly reduce agent consumption, without adversely affecting induction conditions. METHODS: After institutional ethical committee approval, 50 children, aged 1-5 years, undergoing ophthalmic procedures under general anesthesia, were randomized into two groups-standard induction (Group S) and low-flow induction (Group L). A pediatric circle system with 1 L reservoir bag was primed with 8% sevoflurane in oxygen at 6 L min-1 for 30 seconds before beginning induction. In Group S, fresh gas flow was maintained at 6 L min-1 until the end of induction. In Group L, fresh gas flow was reduced to 1 L min-1 after applying facemask (time = T0). In both groups, sevoflurane was reduced to 5% after loss of eyelash reflex (T1). Once adequate depth of anesthesia was achieved (regular respiration, loss of muscle tone, and absence of movement to trapezius squeeze), intravenous access was secured (T2), followed by insertion of an appropriately sized LMA-Classic™ (T3). Heart rate and endtidal sevoflurane concentration were measured at each of the above time points, and at 15 seconds following laryngeal mask airway insertion (T4). The total amount of sevoflurane consumed during induction was recorded. RESULTS: Sevoflurane consumption was significantly lower in Group L (4.17 ± 0.70 mL) compared to Group S (8.96 ± 1.11 mL) (mean difference 4.79 [95% CI = 4.25-5.33] mL; P < 0.001). Time to successful laryngeal mask airway insertion was similar in both groups. There were no significant differences in heart rate, incidence of reflex tachycardia, or need for rescue propofol. CONCLUSION: Induction of anesthesia with sevoflurane using low-fresh gas flow is effective in reducing sevoflurane consumption, without compromising induction time and conditions.

Sources of Variation in Anesthetic Drug Costs.

BACKGROUND: Increasing attention has been focused on health care expenditures, which include anesthetic-related drug costs. Using data from 2 large academic medical centers, we sought to identify significant contributors to anesthetic drug cost variation. METHODS: Using anesthesia information management systems, we calculated volatile and intravenous drug costs for 8 types of inpatient surgical procedures performed from July 1, 2009, to December 31, 2011. For each case, we determined patient age, American Society of Anesthesiologists (ASA) physical status, gender, institution, case duration, in-room provider, and attending anesthesiologist. These variables were then entered into 2 fixed-effects linear regression models, both with logarithmically transformed case cost as the outcome variable. The first model included duration, attending anesthesiologist, patient age, ASA physical status, and patient gender as independent variables. The second model included case type, institution, patient age, ASA physical status, and patient gender as independent variables. When all variables were entered into 1 model, redundancy analyses showed that case type was highly correlated (R = 0.92) with the other variables in the model. More specifically, a model that included case type was no better at predicting cost than a model without the variable, as long as that model contained the combination of attending anesthesiologist and case duration. Therefore, because we were interested in determining the effect both variables had on cost, 2 models were created instead of 1. The average change in cost resulting from each variable compared to the average cost of the reference category was calculated by first exponentiating the ß coefficient and subtracting 1 to get the percent difference in cost. We then multiplied that value by the mean cost of the associated reference group. RESULTS: A total of 5504 records were identified, of which 4856 were analyzed. The median anesthetic drug cost was $38.45 (25th percentile = $23.23, 75th percentile = $63.82). The majority of the variation was not described by our models-35.2% was explained in the model containing case duration, and 32.3% was explained in the model containing case type. However, the largest sources of variation our models identified were attending anesthesiologist, case type, and procedure duration. With all else held constant, the average change in cost between attending anesthesiologists ranged from a cost decrease of $41.25 to a cost increase of $95.67 (10th percentile = -$19.96, 90th percentile = +$20.20) when compared to the provider with the median value for mean cost per case. The average change in cost between institutions was significant but minor ($5.73). CONCLUSIONS: The majority of the variation was not described by the models, possibly indicating high per-case random variation. The largest sources of variation identified by our models included attending anesthesiologist, procedure type, and case duration. The difference in cost between institutions was statistically significant but was minor. While many prior studies have found significant savings resulting from cost-reducing interventions, our findings suggest that because the overall cost of anesthetic drugs was small, the savings resulting from interventions focused on the clinical practice of attending anesthesiologists may be negligible, especially in institutions where access to more expensive drugs is already limited. Thus, cost-saving efforts may be better focused elsewhere.

Cost-effectiveness of anesthesia maintained with sevoflurane or propofol with and without additional monitoring: a prospective, randomized controlled trial.

BACKGROUND: We compared cost-effectiveness of anesthesia maintained with sevoflurane or propofol with and without additional monitoring, in the clinical setting of ear-nose-throat surgery. METHODS: One hundred twenty adult patients were randomized to four groups. In groups SEVO and SEVO+ anesthesia was maintained with sevoflurane, in group SEVO+ with additional bispectral index (BIS) and train-of-four (TOF) monitoring. In groups PROP and PROP+ anesthesia was maintained with propofol, in group PROP+ with additional BIS and TOF monitoring. RESULTS: Total cost of anesthesia per hour was greater in group SEVO+ compared to SEVO [€ 19.95(8.53) vs. 12.15(5.32), p <  0.001], and in group PROP+ compared to PROP (€ 22.11(8.08) vs. 13.23(4.23), p <  0.001]. Time to extubation was shorter in group SEVO+ compared to SEVO [11.1(4.7) vs. 14.5(3.9) min, p = 0.002], and in PROP+ compared to PROP [12.6(5.4) vs. 15.2(4.7) min, p <  0.001]. Postoperatively, arterial blood pressure returned to its initial values sooner in groups SEVO+ and PROP+. CONCLUSIONS: Our study demonstrated that the use of BIS and TOF monitoring decreased the total cost of anesthesia drugs and hastened postoperative recovery. However, in our circumstances, these were associated with higher disposables costs. Detailed cost analysis and further investigations are needed to identify patient populations who would benefit most from additional monitoring. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02920749 . Retrospectively registered (date of registration September 2016).

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.

Ether in the developing world: rethinking an abandoned agent.

BACKGROUND: The first true demonstration of ether as an inhalation anesthetic was on October 16, 1846 by William T.G. Morton, a Boston dentist. Ether has been replaced completely by newer inhalation agents and open drop delivery systems have been exchanged for complicated vaporizers and monitoring systems. Anesthesia in the developing world, however, where lack of financial stability has halted the development of the field, still closely resembles primitive anesthetics. DISCUSSION: In areas where resources are scarce, patients are often not given supplemental intraoperative analgesia. While halothane provides little analgesia, ether provides excellent intra-operative pain control that can extend for several hours into the postoperative period. An important barrier to the widespread use of ether is availability. With decreasing demand, production of the inexpensive inhalation agent has fallen. Ether is inexpensive to manufacture, and encouraging increased production at a local level would help developing nations to cut costs and become more self-sufficient.

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.

A cost-benefit analysis of the ENIGMA trial.

BACKGROUND: The ENIGMA trial was a prospective, randomized, multicenter study that evaluated the clinical consequences of including N2O in general anesthesia. Patients who were given a N2O-free anesthetic when undergoing major surgery for which the expected hospital stay was at least 3 days had lower rates of some postoperative complications. This suggests that, despite a higher consumption of potent inhalational agent, there could be a financial benefit when N2O is avoided in such settings. METHODS: A retrospective cost analysis of the 2,050 patients recruited to the ENIGMA trial was performed. We measured costs from the perspective of an implementing hospital. Direct health care costs include the costs for maintaining anesthesia, daily medications, hospitalization, and complications. The primary outcome was the net financial savings from avoiding N2O in major noncardiac surgery. Comparisons between groups were analyzed using Student t test and bootstrap methods. Sensitivity analyses were also performed. RESULTS: Rates of some serious complications were higher in the N2O group. Total costs in the N2O group were $16,203 and in the N2O-free group $13,837, mean difference of $2,366 (95% CI: 841-3,891); P = 0.002. All sensitivity analyses retained a significant difference in favor of the N2O-free group (all P ≤ 0.005). CONCLUSIONS: Despite N2O reducing the consumption of more expensive potent inhalational agent, there were marked additional costs associated with its use in adult patients undergoing major surgery because of an increased rate of complications. There is no cogent argument to continue using N2O on the basis that it is an inexpensive drug.

Effects of lidocaine infiltration on cost of rhinoplasty made under general anesthesia.

This study aimed to compare the effects of combined and noncombined lidocaine with adrenaline infiltration in general anesthesia (GA) procedures, in which the standard anesthesia depth is monitored by Bispectral Index monitoring, on minimum alveolar concentration (MAC) levels and the costs. Following approval by the local ethics committee, an American Society of Anesthesiologists physical status I­II group of 40 adult patients for whom elective rhinoplasties under GA were planned was divided into 2 double-blind randomized groups. In group 1, GA and lidocaine + adrenaline were administered, whereas in group 2, only GA and adrenaline were administered. All the patients who had been taken to the operation room underwent electrocardiography and measurements of the peripheral oxygen saturation, end-tidal carbon dioxide, heart rate, mean blood pressure, and Bispectral Index monitoring. Using the operation time and the MAC% values, the total consumed inhalation agent amounts were calculated, and the cost difference was determined. The mean blood pressure values were lower in group 1 (P < 0.05). In group 1, the MAC% was 20.83% lower than that of group 2; the consumed desflurane amount was 20.29%, and the cost was 20.29% lower than that of group 2 (P < 0.05). In rhinoplasties under GA, the lidocaine + adrenaline combination infiltration not only decreased inhaled anesthetic requirement and cost but also supported the hemodynamic stability. In addition, surgical satisfaction increased in the lidocaine + adrenaline group because of small number of agitated patients during the recovery period.

Meta-analysis of average and variability of time to extubation comparing isoflurane with desflurane or isoflurane with sevoflurane.

BACKGROUND: We recently determined how to use anesthesia information management system data to model the time from end of surgery to extubation. We applied that knowledge for meta-analyses of trials comparing extubation times after maintenance with desflurane and sevoflurane. In this study, we repeated the meta-analyses to compare isoflurane with desflurane and sevoflurane. METHODS: A Medline search through December 2009 was used to identify studies with (1) humans randomly assigned to isoflurane or desflurane groups without other differences (e.g., induction drugs) between groups, and (2) mean and SD reported for extubation time and/or time to follow commands. The search was repeated for random assignment to isoflurane or sevoflurane groups. We considered extubation times >15 minutes (representing 15% of cases in the anesthesia information management system data) to be prolonged. RESULTS: Desflurane reduced the mean extubation time by 34% and reduced the variability in extubation time by 36% relative to isoflurane. These reductions would reduce the incidence of prolonged extubation times by 95% and 97%, respectively. Sevoflurane reduced the mean extubation time by 13% and reduced the SD by 8.7% relative to isoflurane. These reductions would reduce the incidence of prolonged extubation times by 51% and 35%, respectively. CONCLUSIONS: The pharmacoeconomics of volatile anesthetics are highly sensitive to measurement of relatively small time differences. Therefore, surgical facilities should use these values combined with their local data (e.g., mean baseline extubation times) when making evidence-based management decisions regarding pharmaceutical purchases and usage guidelines.

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.

[Functioning of the anaesthetic conserving device: aspects to consider for use in inhalational sedation]. / Funktionsweise des "Anaesthetic Conserving Device" : Besonderheiten beim Einsatz zur inhalativen Sedierung.

The new anaesthetic conserving device (ACD) allows the use of isoflurane and sevoflurane without classical anaesthesia workstations. Volatile anaesthetic exhaled by the patient is absorbed by a reflector and released to the patient during the next inspiration. Liquid anaesthetic is delivered via a syringe pump. Currently the use of the ACD is spreading among European intensive care units (ICU). This article focuses on the functioning of the device and on particularities which are important to consider. The ACD constantly reflects 90% of the exhaled anaesthetic back to the patient, but if one exhaled breath contains more than 10 ml of anaesthetic vapour (e.g. >1 vol% in 1,000 ml), the capacity of the reflector will be exceeded and relatively more anaesthetic will be lost to the patient. This spill over decreases efficiency but it also contributes to safety as very high concentrations are averted. Compared to classical anaesthesia systems the ACD used in conjunction with ICU ventilators offers advantages in the ICU setting: investment costs are low, carbon dioxide absorbent is not needed, breathing comfort is higher, anaesthetic consumption is low (equal to an anaesthesia circuit with a fresh gas flow of approximately 1 l/min) and anaesthetic concentrations can be controlled very quickly (increased by small boluses and decreased by removal of the ACD). On the other hand, case costs are higher (single patient use) and a dead space of 100 ml is added. There are pitfalls: by a process called auto-pumping, expansion of bubbles inside the syringe may lead to uncontrolled anaesthetic delivery. Auto-pumping is provoked by high positioning of the syringe pump, heat and prior cooling of the liquid anaesthetic. Inherent to the device is an early inspiratory concentration peak and an end-inspiratory dip which may mislead commonly used gas monitors. Workplace concentrations can be minimized by proper handling, a sufficient turnover of room air is important and gas from the expiration port of the ventilator should be scavenged. Inhalational compared to intravenous ICU sedation offers the advantages of better control of the sedation level, online drug monitoring, no accumulation in patients with renal or hepatic insufficiency and bronchodilation. With a lowered opioid dose spontaneous breathing and intestinal motility are well preserved. A clinical algorithm for the care of patients with respiratory insufficiency including inhalational sedation is proposed. Inhalational sedation with isoflurane has been widely used for more than 20 years in many countries and even for periods of up to several weeks. In the German S3 guidelines for the management of analgesia, sedation and delirium in intensive care (Martin et al. 2010), inhalational sedation is mentioned as an alternative sedation method for patients ventilated via an endotracheal tube or a tracheal cannula. Nevertheless, isoflurane is not officially licensed for ICU sedation and its use is under the responsibility of the prescribing physician.