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Guidelines recommend the use of ultrasound in cardiac arrest. Transthoracic echocardiography, has issues with image quality and by increasing hands-off times during resuscitation. We assessed the feasibility of transesophageal echocardiography (TEE), which does not have both problems, at out-of-hospital cardiac arrest (OHCA) emergency scenes. Included were 10 adults with non-traumatic OHCA in Vienna, Austria. An expert in emergency ultrasound was dispatched to the scenes in addition to the resuscitation team. Feasibility was defined as the ability to collect specific items of information by TEE within 10 min. Descriptive statistics were compiled and hands-off times were compared to a historical control group. TEE examinations were feasible in 9 of 10 cases and prompted changes in clinical management in 2 cases (cardiac tamponade: n = 1; right ventricular dilatation: n = 1). Their mean time requirement was 5.1 ± 1.7 (2.8-8.0) min, and image quality was invariably rated as excellent or good during both compressions and pauses. No TEE-related complications, or interferences with activities of advanced life support were observed. The hands-off times during resuscitation were comparable to a historical control group not involving ultrasound (P = 0.24). Given these feasibility results, we expect that TEE can be used routinely at OHCA emergency scenes., (© 2023. The Author(s).)

While the initial minutes of acute emergencies significantly influence clinical outcomes, prehospital research often receives inadequate attention due to several challenges. Retrospective chart reviews carry the risk of incomplete and inaccurate data. Furthermore, prehospital intervention trials frequently encounter difficulties related to extensive training requirements, even during the planning phase. Consequently, we have implemented prospective research concepts involving additional paramedics and physicians directly at the scene during major emergency calls. Three concepts were used: (I) Paramedic field supervisor units, (II) a paramedic + physician field supervisor unit, (III) a special physician-based research car. This paper provides insights into our historical perspective, the current situation, and the lessons learned while overcoming certain barriers and using existing and novel facilitators. Our objective is to support other research groups with our experiences in their planning of upcoming prehospital trials., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 Published by Elsevier B.V.)

Background: Although one-half of all public out-of-hospital cardiac arrests (OHCAs) occur outside private homes in residential neighborhoods, their characteristics and outcomes remain unexplored., Objectives: The authors assessed interventions before ambulance arrival and survival for public OHCA patients in residential neighborhoods., Methods: Public OHCAs from Vienna (2018-2021) and Copenhagen (2016-2020) were designated residential neighborhoods or nonresidential areas. Interventions (cardiopulmonary resuscitation [CPR], automated external defibrillator [AED] attached, and defibrillation) and 30-day survival were compared using a generalized estimation equation model adjusted for age and time of day and presented as ORs., Results: We included 1,052 and 654 public OHCAs from Vienna and Copenhagen, respectively, and 68% and 55% occurred in residential neighborhoods, respectively. The likelihood of CPR, defibrillation, and survival in residential neighborhoods vs nonresidential areas (reference) were as follows: CPR Vienna, 73% vs 78%, OR: 0.78 (95% CI: 0.57-1.06), CPR Copenhagen, 83% vs 90%, OR: 0.54 (95% CI: 0.34-0.88), and CPR combined, 76% vs 84%, OR: 0.70 (95% CI: 0.53-0.90); AED attached Vienna, 36% vs 44%, OR: 0.69 (95% CI: 0.53-0.90), AED attached Copenhagen, 21% vs 43%, OR: 0.33 (95% CI: 0.24-0.48), and AED attached combined, 31% vs 44%, OR: 0.53 (95% CI: 0.42-0.65); defibrillation Vienna, 14% vs 20%, OR: 0.61 (95% CI: 0.43-0.87), defibrillation Copenhagen, 16% vs 36%, OR: 0.35 (95% CI: 0.24-0.51), and defibrillation combined, 15% vs 27%, OR: 0.46 (95% CI: 0.36-0.61); and 30-day survival rate Vienna, 21% vs 26%, OR: 0.84 (95% CI: 0.58-1.20), 30-day survival rate Copenhagen, 33% vs 44%, OR: 0.65 (95% CI: 0.47-0.90), and 30-day survival rate combined, 25% vs 36%, OR: 0.73 (95% CI: 0.58-0.93)., Conclusions: Two-thirds of public OHCAs occurred in residential neighborhoods with fewer resuscitative efforts before ambulance arrival and lower survival than in nonresidential areas. Targeted efforts to improve early CPR and defibrillation for public OHCA patients in residential neighborhoods are needed., Competing Interests: Funding Support and Author Disclosures Dr Grabmayr has received a research grant from Trygfonden. Dr Folke has received research grants from the Novo Nordisk Foundation (NNF19OC0055142), TrygFonden, and the Laerdal Foundation. Dr Hansen has received research grants from TrygFonden, Helsefonden, the Laerdal Foundation, and the Capital Region of Denmark, Research Fund. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Out-of-hospital cardiac arrest with subsequent cardiopulmonary resuscitation (CPR) still leads to dismal outcomes worldwide. The crucial gap between cardiac arrest and advanced life support can only be filled by bystander-CPR. However, knowledge and willingness of the public towards basic life support (BLS) remain low. Global and national initiatives for awareness building and CPR training have produced promising improvements, but an additional focus on regional initiatives might be necessary to truly implement change., Methods and Results: In order to support other like-minded groups, we present a "coming of age" narrative review of PULS - Austrian Cardiac Arrest Awareness Association, along with a future outlook and "lessons learned". Interviews with past and present employees, members, and functionaries were conducted by the authors. Additionally, the organization's archives were assessed., Conclusion: Following current guidelines and the Utstein formula of survival, building a system to save lives is essential to achieve progress concerning cardiac arrest survival and outcomes. As kinds of "regional offices" of global resuscitation efforts, a network of individual local initiatives and organizations such as PULS can carry the respective messages, engage with local key figures of implementation, and keep up perpetual work for cardiac arrest awareness and BLS education., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

First responders are an essential part of the chain (-mail) of survival as they bridge and reduce the time to first chest compressions and defibrillation substantially. However, in the peri-mission phase before and after being sent to a cardiac arrest, these first responders are in danger of being forgotten and taken for granted, and the potential psychological impact has to be remembered. We propose a standardized first responder support system (FRSS) that needs to ensure that first responders are valued and cared for in terms of psychological safety and continuing motivation. This multi-tiered program should involve tailored education and standardized debriefing, as well as actively seeking contact with the first responders after their missions to facilitate potentially needed professional psychological support., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

Background: Purinergic signaling receptor Y 12 (P2Y 12 ) inhibitors are a fundamental part of pharmacological therapy in acute coronary syndrome (ACS) for preventing recurrent ischemic events. Current guidelines support the use of prasugrel over ticagrelor-however, ticagrelor is widely used for preclinical loading during ACS due to its ease of administration. In this regard, it remains unknown whether the preclinical loading with P2Y 12 inhibitors impacts decision-making for the long-term dual antiplatelet strategy, as well as cardiovascular outcomes, including re-percutaneous coronary intervention in real-world settings., Methods: Within this population-based prospective observational study, all patients with ACS who received medical care via the Emergency Medical Service (EMS) in the city of Vienna between January 2018 and October 2020 were enrolled. Patients were stratified according to their P2Y 12 inhibitor loading regimen. Subsequently, the association of P2Y 12 inhibitor loading on long-term prescription at discharge and outcome was assessed., Results: The entire study cohort consisted of 1176 individuals with ST-elevation myocardial infarction (STEMI), of whom 47.5% received prasugrel and 52.5% ticagrelor. The likelihood of adhering to the initial P2Y 12 inhibitor strategy during the clinical stay was high for both ticagrelor (84%; OR: 10.00; p < 0.001) and prasugrel (77%; OR: 21.26; p < 0.001). During patient follow-up (median follow-up time three years), 84 (7.1%) patients died due to cardiovascular causes, and 82 (7.0%) patients required re-PCI. Notably, there was no difference in cardiovascular mortality (6.6% ticagrelor vs. 7.7% prasugrel) or re-PCI rates (6.6% ticagrelor vs. 7.3% prasugrel) addressing the P2Y 12 inhibition strategy., Conclusion: We observed that, regardless of the initial antiplatelet inhibitor strategy, the in-hospital P2Y 12 adherence was exceedingly high, and there was a minimal occurrence of switching to another P2Y 12 inhibitor. Most importantly, no significant difference in cardiovascular death/re-PCI between ticagrelor and prasugrel-based preclinical loading has been observed. Consequently, the choice of high potent P2Y 12 did not influence the cardiac outcome from a long-term perspective.

Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: ‘DF is co-founder and operations manager of the Heartrunner Citizen Responder System, Sweden and member of the tech&ops committee of EENA (European Emergency Number Association). CM is Guest Editor special issue “Impact of First Responders in Resuscitation” in Resuscitation Plus. MPM is chair of Region of Lifesavers, shareholder of SmartResQ ApS, and received speaker honoraria from Stryker. TS is the Social Media Editor of Resuscitation and Resuscitation Plus journals. All other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper’.

Background: Police first responder systems also including automated external defibrillation (AED) has in the past shown considerable impact on favourable outcomes after out-of-hospital cardiac arrest (OHCA). While short hands-off times in chest compressions are known to be beneficial, various AED models use different algorithms, inducing longer or shorter durations of crucial timeframes along basic life support (BLS). Yet, data on details of these differences, and also of their potential impact on clinical outcomes are scarce. Methods: For this retrospective observational study, patients with OHCA of presumed cardiac origin and initially shockable rhythm treated by police first responders in Vienna, Austria, between 01/2013 and 12/2021 were included. Data from the Viennese Cardiac Arrest Registry and AED files were extracted, and exact timeframes were analyzed. Results: There were no significant differences in the 350 eligible cases in demographics, return of spontaneous circulation, 30-day survival, or favourable neurological outcome between the used AED types. However, the Philips HS1 and -FrX AEDs showed immediate rhythm analysis after electrode placement (0 [0-1] s) and almost no shock loading time (0 [0-1] s), as opposed to the LP CR Plus (3 [0-4] and 6 [6-6] s, respectively) and LP 1000 (3 [2-10] and 6 [5-7] s, respectively). On the other hand, the HS1 and -FrX had longer analysis times of 12 [12-16] and 12 [11-18] s than the LP CR Plus (5 [5-6] s) and LP 1000 (6 [5-8] s). The duration from when the AED was turned on until the first defibrillation were 45 [28-61] s (Philips FrX), 59 [28-81] s (LP 1000), 59 [50-97] s (HS1), and 69 [55-85] s (LP CR Plus). Conclusion: In a retrospective analysis of OHCA-cases treated by police first responders, we could not find significant differences in clinical patient outcomes concerning the respective used AED model. However, various differences in time durations (e.g., electrode placement to rhythm analysis, analysis duration, or AED turned on until first defibrillation) along the BLS algorithm were seen. This opens up the question of AED-adaptations and tailored training methods for professional first responders., Competing Interests: M.K. is medical director of the Viennese EMS. S.S. is Vice-Chair of the Austrian Resuscitation Council, ILCOR EIT Task Force member, ERC ALS SEC member and YERC Research Representative. The other authors declare no COI relevant to this study.

Background: The city of Vienna, Austria, has a gradually aging population. Elderly people, over 65 years old and living at home or in nursing homes, frequently use Emergency Medical Services (EMS). However, there is no previous data comparing the EMS utilization of elderly- and non-elderly patients in Vienna. Methods: We retrospectively analyzed all EMS incidents in Vienna from 2012 to 2019. Transport- and emergency physician treatment rates, annual fluctuations, and the number of non-transports were compared between elderly (≥65 years) and non-elderly (18−64 years) patients. Results: Elderly people accounted for 42.6% of the total EMS responses in adult patients, representing an annual response rate of 223 per 1000 inhabitants ≥ 65 years. Compared to 76 per 1000 inhabitants in patients 18−64 years old, this results in an incidence rate ratio (IRR) of 2.93 [2.92−2.94]. Elderly people were more likely (OR 1.68 [1.65−1.70]) to need emergency physicians, compared to 18−64 year-olds. Nursing home residents were twice (OR 2.11 [2.06−2.17]) as likely to need emergency physicians than the rest of the study group. Non-transports were more likely to occur in patients over 65 years than in non-elderlies (14% vs. 12%, p < 0.001). Conclusions: The elderly population ≥ 65 years in Vienna shows higher EMS response rates than younger adults. They need emergency physicians more often, especially when residing in nursing homes. The economical and organizational strain this puts on the emergency response system should trigger further research and the development of solutions, such as specific response units dedicated to elderly people.

Aims: Due to time-critical decision-making, physical strain and the uncontrolled environment, prehospital emergency management is frequently associated with high levels of stress in medical personnel. Stress has been known to cause ischemia like changes in electrocardiograms (ECGs), including arrhythmias and deviations in ST-T segments. There is a lack of knowledge regarding the occurrence of changes in ST-T segments in prehospital emergency physicians. We hypothesized that ST-T segment deviations occur in prehospital emergency physicians in the field., Methods: In this prospective observational trial, ST-T segments of emergency physicians were recorded using 12-lead Holter ECGs. The primary outcome parameter was defined as the incidence of ST-T segment changes greater than 0.1 mV in two corresponding leads for more than 30 s per 100 rescue missions. The secondary outcomes included T-wave inversions and ST-segment changes shorter than 30 s or smaller than 0.1 mV. Surrogate parameters of stress were measured using the NASA-Task Load Index and cognitive appraisal, and their correlation with ST-T segment changes were also assessed., Results: Data from 20 physicians in 36 shifts (18 days, 18 nights) including 208 missions were analysed. Seventy percent of previously healthy emergency physicians had at least one ECG abnormality; the mean duration of these changes was 30 s. Significantly more missions with ECG changes were found during night than day shifts (39 vs. 17%, p < 0.001). Forty-nine ECG changes occurred between missions. No ST-T segment changes > 30 s and > 0.1 mV were found. Two ST-T segment changes < 30 s or < 0.1 mV (each during missions) and 122 episodes of T-wave inversions (74 during missions) were identified. ECG changes were found to be associated with alarms when asleep and NASA task load index., Conclusion: ECG changes are frequent and occur in most healthy prehospital emergency physicians. Even when occurring for less than 30 s, such changes are important signs for high levels of stress. The long-term impact of these changes needs further investigation. Trial registration The trial was registered at ClinicalTrials.gov (NCT04003883) on 1.7.2019:  https://clinicaltrials.gov/ct2/show/NCT04003883?term=emergency+physician&rank=2., (© 2022. The Author(s).)

Background: The COVID-19 pandemic led to widespread use of personal protection equipment (PPE), including filtering face piece (FFP) masks, throughout the world. PPE. Previous studies indicate that PPE impairs neurocognitive performance in healthcare workers. Concerns for personnel safety have led to special recommendations regarding basic life support (BLS) in patients with a potential SARS-CoV-2 infection, including the use of PPE. Established instruments are available to assess attention and dexterity in BLS settings, respectively. We aimed to evaluate the influence of PPE with different types of FFP masks on these two neuropsychological components of EMS personnel during BLS., Methods: This was a randomized controlled non-inferiority triple-crossover study. Teams of paramedics completed three 12-min long BLS scenarios on a manikin after having climbed three flights of stairs with equipment, each in three experimental conditions: (a) without pandemic PPE, (b) with PPE including a FFP2 mask with an expiration valve and (c) with PPE including an FFP2 mask without an expiration valve. The teams and intervention sequences were randomized. We measured the shift in concentration performance using the d2 test and dexterity using the nine-hole peg test (NHPT). We compared results between the three conditions. For the primary outcome, the non-inferiority margin was set at 20 points., Results: Forty-eight paramedics participated. Concentration performance was significantly better after each scenario, with no differences noted between groups: d2 shift control versus with valve - 8.3 (95% CI - 19.4 to 2.7) points; control versus without valve - 8.5 (- 19.7 to 2.7) points; with valve versus without valve 0.1 (- 11.1 to 11.3) points. Similar results were found for the NHPT: + 0.3 (- 0.7 to 1.4), - 0.4 (- 1.4 to 0.7), 0.7 (- 0.4 to 1.8) s respectively., Conclusion: Attention increases when performing BLS. Attention and dexterity are not inferior when wearing PPE, including FFP2 masks. PPE should be used on a low-threshold basis., (© 2022. The Author(s).)

Background: Over the past decade Smartphone-based activation (SBA) of Community First Responders (CFR) to out-of-hospital cardiac arrests (OHCA) has gained much attention and popularity throughout Europe. Various programmes have been established, and interestingly there are considerable differences in technology, responder spectrum and the degree of integration into the prehospital emergency services. It is unclear whether these dissimilarities affect outcome. This paper reviews the current state in five European countries, reveals similarities and controversies, and presents consensus statements generated in an international conference with the intention to support public decision making on future strategies for SBA of CFR., Methods: In a consensus conference a three-step approach was used: (i) presentation of current research from five European countries; (ii) workshops discussing evidence amongst the audience to generate consensus statements; (iii) anonymous real-time voting applying the modified RAND-UCLA Appropriateness method to adopt or reject the statements. The consensus panel aimed to represent all stakeholders involved in this topic., Results: While 21 of 25 generated statements gained approval, consensus was only found for 5 of them. One statement was rejected but without consensus. Members of the consensus conference confirmed that CFR save lives. They further acknowledged the crucial role of emergency medical control centres and called for nationwide strategies., Conclusions: Members of the consensus conference acknowledged that smartphone-based activation of CFR to OHCA saves lives. The statements generated by the consensus conference may assist the public, healthcare services and governments to utilise these systems to their full potential, and direct the research community towards fields that still need to be addressed.

Background: Laypersons' efforts to initiate basic life support (BLS) in witnessed Out-of-Hospital Cardiac Arrest (OHCA) remain comparably low within western society. Therefore, in order to shorten no-flow times in cardiac arrest, several police-based first responder systems equipped with automated external defibrillators (Pol-AED) were established in urban areas, which subsequently allow early BLS and AED administration by police officers. However, data on the quality of BLS and AED use in such a system and its impact on patient outcome remain scarce and inconclusive., Methods: A total of 85 Pol-AED cases were randomly assigned to a gender, age and first rhythm matched non-Pol-AED control group (n = 170) in a 1:2 ratio. Data on quality of BLS were extracted via trans-thoracic impedance tracings of used AED devices., Results: Comparing Pol-AED cases and the control group, we observed a similar compression rate per minute (p = 0.677) and compression ratio (p = 0.651), mirroring an overall high quality of BLS administered by police officers. Time to the first shock was significantly shorter in Pol-AED cases (6 minutes [IQR: 2-10] vs. 12 minutes [IQR: 8-17]; p<0.001). While Pol-AED was not associated with increased sustained return of spontaneous circulation (p = 0.564), a strong and independent impact on survival until hospital discharge (adj. OR: 1.85 [95%CI: 1.06-3.23; p = 0.030]) and a borderline significance for the association with favorable neurological outcome (adj. OR: 1.58 [95%CI: 0.96-2.89; p = 0.052) were observed., Conclusion: We were able to demonstrate an early start and a high quality of BLS and AED use in Pol-AED assessed OHCA cases. Moreover, the presence of Pol-AED care was associated with better patient survival and borderline significance for favorable neurological outcome., Competing Interests: The authors have declared that no competing interests exist.

Background: Cardio-pulmonary-resuscitation (CPR) training starting at the age of 12 years is recommended internationally. Training younger children is not recommended because young children lack the physical ability to perform adequate CPR and discouragement to perform CPR later is apprehended. The aim of this study was to answer the following questions: Are younger children discouraged after CPR training? Is discouragement caused by their lack in physical ability to perform adequate chest compressions on a standard manikin and would the use of manikins with a reduced resistance affect their motivation or performance?, Methods: We investigated the motivation and CPR performance of children aged 8-13 years after CPR training on manikins of different chest stiffness in a prospective, randomized, single-blind, controlled trial. 322 children underwent randomization and received 30 minutes CPR training in small groups at school. We used two optically identical resuscitation manikins with different compression resistances of 45kg and 30kg. Motivation was assessed with a self-administered questionnaire. Performance was measured with the Resusci®Anne SkillReporter™., Findings: Motivation after the training was generally high and there was no difference between the two groups in any of the questionnaire items on motivation: Children had fun (98 vs. 99%; P = 0.32), were interested in the training (99 vs. 98%; P = 0.65), and were glad to train resuscitation again in the future (89 vs. 91%; P = 0.89). CPR performance was generally poor (median compression score (8, IQR 1-45 and 29, IQR 11-54; P<0.001) and the mean compression depth was lower in the 45kg-resistance than in the 30kg-resistance group (33±10mm vs. 41±9; P<0.001)., Conclusions: Compression resistances of manikins, though influencing CPR performance, did not discourage 8 to 13 year old children after CPR training. The findings refute the view that young children are discouraged when receiving CPR training even though they are physically not able to perform adequate CPR., Competing Interests: The authors have declared that no competing interest exists.

Background: The 'chain of survival'-including early call for help, early cardiopulmonary resuscitation (CPR) and early defibrillation-represents the most beneficial approach for favourable patient outcome after out-of-hospital cardiac arrest (OHCA). Despite increasing numbers of publicly accessible automated external defibrillators (AED) and interventions to increase public awareness for basic life support (BLS), the number of their use in real-life emergency situations remains low., Methods: In this prospective population-based cross-sectional study, a total of 501 registered inhabitants of Vienna (Austria) were randomly approached via telephone calls between 08/2014 and 09/2014 and invited to answer a standardized questionnaire in order to identify public knowledge and awareness of BLS and AED-use., Results: We found that more than 52 percent of participants would presume OHCA correctly and would properly initiate BLS attempts. Of alarming importance, only 33 percent reported that they would be willing to perform CPR and 50 percent would use an AED device. There was a significantly lower willingness to initiate BLS attempts (male: 40% vs. female: 25%; OR: 2.03 [95%CI: 1.39-2.98]; p<0.001) and to use an AED device (male: 58% vs. female: 44%; OR: 1.76 [95%CI: 1.26-2.53]; p = 0.002) in questioned female individuals compared to their male counterparts. Interestingly, we observed a strongly decreasing level of knowledge and willingness for BLS attempts (-14%; OR: 0.72 [95%CI: 0.57-0.92]; p = 0.027) and AED-use (-19%; OR: 0.68 [95%CI: 0.54-0.85]; p = 0.001) with increasing age., Conclusion: We found an overall poor knowledge and awareness concerning BLS and the use of AEDs among the Viennese population. Both female and elderly participants reported the lowest willingness to perform BLS and use an AED in case of OHCA. Specially tailored programs to increase awareness and willingness among both the female and elderly community need to be considered for future educational interventions., Competing Interests: The authors have declared that no competing interests exist.

Background: The anesthetic effect of volatile anesthetics can be quantified by the minimum alveolar concentration (MAC) of the drug that prevents movement in response to a noxious stimulus in 50% of patients. The underlying mechanism regarding how immobilization is achieved by volatile anesthetics is not thoroughly understood, but several drugs affect MAC. In this study, we investigated the effect of a single IV bolus dose of lidocaine on the MAC of sevoflurane in humans., Methods: We determined the MAC for sevoflurane using the Dixon "up-and-down" method in 3 groups of patients, aged 30 to 65 years, who underwent elective surgery (30 patients per group). Study medication (placebo, 0.75 mg·kg(-1) lidocaine or 1.5 mg·kg(-1) lidocaine) was administered 3 minutes before skin incision after a 15-minute equilibration period and the response to skin incision was recorded (movement versus no movement)., Results: MAC was 1.86% ± 0.40% in the placebo and 1.87% ± 0.45% in the 0.75 mg·kg(-1) lidocaine group (P = 1.00). MAC was 1.63% ± 0.24% in the 1.5 mg·kg(-1) lidocaine group, which was significantly lower than that of the placebo group (mean difference of 0.23% sevoflurane [95% adjusted confidence interval {CI}, 0.03-0.43]; P = 0.022). No significant difference was observed between the 0.75 mg·kg(-1) lidocaine and the placebo groups (mean difference of -0.01% sevoflurane [95% adjusted CI, -0.27 to 0.25]; P = 1)., Conclusions: IV 1.5 mg·kg(-1) lidocaine decreased the MAC by at least 0.03% sevoflurane (mean difference 0.23% sevoflurane [95% adjusted CI, 0.03-0.43]). We did not observe a significant reduction in the MAC of sevoflurane with the IV administration of 0.75 mg·kg(-1) lidocaine.