Nasal cannula and face mask gas flow rates when connecting to the Y-piece of the anesthesia circuit.

STUDY OBJECTIVE: To determine the relationship between the delivered gas flows via nasal cannulas and face masks and the set gas flow and the breathing circuit pressure when connecting to the Y-adapter of the anesthesia breathing circuit and using the oxygen blender on the anesthesia machine, relevant to surgery when there is concern for causing a fire. The flow rates that are delivered at various flow rates and circuit pressures have not been previously studied. DESIGN: Laboratory investigation. SETTING: Academic medical center. PATIENTS: None. INTERVENTIONS: The gas flows from each of 3 anesthesia machines from the same manufacturer were systematically increased from 1 to 15 L/min with changes to the adjustable pressure limiting valve to maintain 0-40 cm water pressure in the breathing circuit for nasal cannula testing and at 20-30 cm water circuit pressure for face masks. MEASUREMENTS: The delivered gas flows to the cannula were determined using a float-ball flowmeter for combinations of set gas flows and circuit pressures after connecting the cannula tubing to the Y-piece of the anesthesia circuit via a tracheal tube adapter. Decreasing the supply tubing length on the delivered flow rates was evaluated. MAIN RESULTS: There was a highly linear relationship between the anesthesia circuit pressure and the delivered nasal cannula flow rates, with 0 flow observed when the APL valve was fully open (i.e., 0 cm water). However, even under maximum conditions (40 cm water and 15 L/min), the delivered nasal cannula flow rate was 3.5 L/min. Shortening the 6.5-ft cannula tubing increased the flow at 20 and 30 cm water by approximately 0.12 L/min/ft. The estimated FiO2 assuming a minute ventilation of 5 L/min and 30% FiO2 ranged from 21.7% to 27.0% at nasal cannula flow rates of 0.5 to 4.0 L/min. When using a face mask and the APL fully closed, delivered flow rates were 0.25 L/min less than the set flow rate between 1 and 3 L/min and equal to the set flow rate between 4 and 8 L/min. CONCLUSIONS: When using a nasal cannula adapted to the Y-piece of the anesthesia circuit, the delivery system is linearly dependent on the pressure in the circuit and uninfluenced by the flow rate set on the anesthesia machine. However, only modest flow rates (≤ 3.5 L/min) and a limited increase in the inspired FiO2 are possible when using this delivery method. When using a face mask and the anesthesia circuit, flow rates close to the set flow rate are possible with the APL valve fully closed. Patients scheduled for sedation for head and neck procedures with increased fire risk who require more than a marginal increase in the FiO2 to maintain an acceptable pulse oximetry saturation may need general anesthesia with tracheal intubation.

Effect of a non-reactive absorbent with or without environmentally oriented electronic feedback on anesthesia provider's fresh gas flow rates: A greening initiative.

STUDY OBJECTIVE: To examine the effects of a non-reactive carbon dioxide absorbent (AMSORB® Plus) versus a traditional carbon dioxide absorbent (Medisorb™) on the FGF used by anesthesia providers and an electronic educational feedback intervention using Carestation™ Insights (GE HealthCare) on provider-specific change in FGF. DESIGN: Prospective, single-center cohort study set in a greening initiative. SETTING: Operating room. PARTICIPANTS: 157 anesthesia providers (i.e., anesthesiology trainees, certified registered nurse anesthetists, and solo anesthesiologists). INTERVENTIONS: Intervention #1 was the introduction of AMSORB® Plus into 8 Aisys CS2, Carestation™ Insights-enabled anesthesia machines (GE HealthCare) at the study site. At the end of week 6, anesthesia providers were educated and given an environmentally oriented electronic feedback strategy for the next 12 weeks of the study (Intervention #2) using Carestation™ Insights data. MEASUREMENTS: The dual primary outcomes were the difference in average daily FGF during maintenance anesthesia between machines assigned to AMSORB® Plus versus Medisorb™ and the provider-specific change in average fresh gas flows after 12 weeks of feedback and education compared to the historical data. MAIN RESULTS: Over the 18-week period, there were 1577 inhaled anesthetics performed in the 8 operating rooms (528 for intervention 1, 1049 for intervention 2). There were 1001 provider days using Aisys CS2 machines and 7452 provider days of historical data from the preceding year. Overall, AMSORB® Plus was not associated with significantly less FGF (mean - 80 ml/min, 97.5% confidence interval - 206 to 46, P = .15). The environmentally oriented electronic feedback intervention was not associated with a significant decrease in provider-specific mean FGF (-112 ml/min, 97.5% confidence interval - 244 to 21, P = .059). CONCLUSIONS: This study showed that introducing a non-reactive absorbent did not significantly alter FGF. Using environmentally oriented electronic feedback relying on data analytics did not result in significantly reduced provider-specific FGF.

Carbon Dioxide Absorption During Inhalation Anesthesia: A Modern Practice.

CO2 absorbents were introduced into anesthesia practice in 1924 and are essential when using a circle system to minimize waste by reducing fresh gas flow to allow exhaled anesthetic agents to be rebreathed. For many years, absorbent formulations consisted of calcium hydroxide combined with strong bases like sodium and potassium hydroxide. When Sevoflurane and Desflurane were introduced, the potential for toxicity (compound A and CO, respectively) due to the interaction of these agents with absorbents became apparent. Studies demonstrated that strong bases added to calcium hydroxide were the cause of the toxicity, but that by eliminating potassium hydroxide and reducing the concentration of sodium hydroxide to <2%, compound A and CO production is no longer a concern. As a result, CO2 absorbents have been developed that contain little or no sodium hydroxide. These CO2 absorbent formulations can be used safely to minimize anesthetic waste by reducing fresh gas flow to approach closed-circuit conditions. Although absorbent formulations have been improved, practices persist that result in unnecessary waste of both anesthetic agents and absorbents. While CO2 absorbents may seem like a commodity item, differences in CO2 absorbent formulations can translate into significant performance differences, and the choice of absorbent should not be based on unit price alone. A modern practice of inhalation anesthesia utilizing a circle system to greatest effect requires reducing fresh gas flow to approach closed-circuit conditions, thoughtful selection of CO2 absorbent, and changing absorbents based on inspired CO2.

Reflection Versus Rebreathing for Administration of Sevoflurane During Minor Gynecological Surgery.

BACKGROUND: Contemporary anesthetic circle systems, when used at low fresh gas flows (FGF) to allow rebreathing of anesthetic, lack the ability for rapid dose titration. The small-scale anesthetic reflection device Anaesthetic Conserving Device (50mL Version; AnaConDa-S) permits administration of volatile anesthetics with high-flow ventilators. We compared washin, washout, and sevoflurane consumption using AnaConDa-S versus a circle system with low and minimal FGF. METHODS: Forty patients undergoing breast surgery were randomized to receive 0.5 minimal alveolar concentration (MAC) sevoflurane with AnaConDa-S (21 patients, reflection group) or with a circle system (low flow: FGF = 0.2 minute ventilation [V'E], 9 patients; or minimal flow: 0.1 V'E, 10 patients). In the reflection group, syringe pump boluses were given for priming and washin; to simulate an open system, the FGF of the anesthesia ventilator was set to 18 L·min-1 with the soda lime removed. In the other groups, the FGF was increased for washin (1 V'E for 8 minutes) and washout (3 V'E). For all patients, tidal volume was 7 mL·kg-1 and the respiratory rate adjusted to ensure normoventilation. Analgesia was attained with remifentanil 0.3 µg·kg-1·min-1. Sevoflurane consumption was compared between the reflection group and the low- and minimal-flow groups, respectively, using a post hoc test (Fisher Least Significant Difference). To compare washin and washout (half-life), the low- and minimal-flow groups were combined. RESULTS: Sevoflurane consumption was reduced in the reflection group (9.4 ± 2.0 vs 15.0 ± 3.5 [low flow, P < .001] vs 11.6 ± 2.3 mL·MAC h-1 [minimal flow, P = .02]); washin (33 ± 15 vs 49 ± 12 seconds, P = .001) and washout (28 ± 15 vs 55 ± 19 seconds, P < .001) times were also significantly shorter. CONCLUSIONS: In this clinical setting with short procedures, low anesthetic requirements, and low tidal volumes, AnaConDa-S decreased anesthetic consumption, washin, and washout times compared to a circle system.

Automatic regulation of the endotracheal tube cuff pressure with a portable elastomeric device. A randomised controlled study.

BACKGROUND: Intermittent manual correction of the endotracheal tube cuff pressure (Pcuff) may delay the detection of underinflation (source of contaminated oropharyngeal content microaspiration) or overinflation (exposing to airway damage). Devices for automated continuous correction of Pcuff are appealing but some are inconvenient, expensive or even harmful. This prospective randomised controlled study tested whether the tracoe Smart Cuff Manager™ reduced the rate of patients undergoing≥1 episode of underinflation (Pcuff<20 cmH2O), as compared with routine manual Pcuff correction. The rate of patients with≥1 overinflation episode (Pcuff>30 cmH2O) and the incidence of under/overinflation were also compared. METHODS: Patients with acute brain injury and likely to receive invasive mechanical ventilation for>48h were randomly allocated to receive, during 48h, automated Pcuff correction (combined with manual correction) or manual correction alone. Pcuff was measured with a dedicated manual manometer, at least every 8h. RESULTS: Sixty patients were included and randomised (32 patients with manual and 28 with automated Pcuff correction) for 506 measurements of Pcuff (269 and 237, respectively). Automated correction of Pcuff was associated with a lower rate of patients with≥1 episode of underinflation (63% and 18%, respectively, P<0.001), a lower incidence of underinflation episodes (15% vs. 2%; P<0.001), a lower rate of manual corrections (77% vs. 58%; P<0.001). For overinflation, there were no significant between-groups differences (2% vs. 2%). The incidence of early respiratory infections was similar in both groups (29% vs. 25%, P=0.78). CONCLUSIONS: The adjunction of continuous Pcuff control with the Tracoe Smart Cuff Manager™ to routine manual intermittent correction reduced the incidence of Pcuff underinflation episodes without provoking overinflation. TRIAL REGISTRATION: ClinicalTrials NCT03330379. Registered 6 November 2017, https://clinicaltrials.gov/ct2/show/NCT03330379.

Comparison of the use of AnaConDa® versus AnaConDa-S® during the post-operative period of cardiac surgery under standard conditions of practice.

Changes have been made to the AnaConDa device (Sedana Medical, Stockholm, Sweden), decreasing its size to reduce dead space and carbon dioxide (CO2) retention. However, this also involves a decrease in the surface area of the activated carbon filter. The CO2 elimination and sevoflurane (SEV) reflection of the old device (ACD-100) were thus compared with the new version (ACD-50) in patients sedated after coronary artery bypass graft surgery. After ERC approval and written informed consent, 23 patients were sedated with SEV, using first the ACD-100 and then the ACD-50 for 60 min each. With each device, patients were ventilated with tidal volumes (TV) of 5 ml/kg of ideal body weight for the first 30 min, and with 7 ml/kg for the next 30 min. Ventilation parameters, arterial blood gases, Bispectral-Index™ (BIS, Aspect Medical Systems Inc., Newton, MA, USA), SEV concentrations exhaled by the patient (SEV-exhaled) and from the expiratory hose (SEV-lost) were recorded every 30 min. A SEV reflection index was calculated: SRI [%] = 100 × (1 - (SEV-lost/SEV-exhaled)). Data were compared using ANOVA with repeated measurements and Student's T-tests for pairs. Respiratory rates, tidal and minute volumes were not significantly different between the two devices. End tidal and arterial CO2 partial pressures were significantly higher with the ACD-100 as compared with the ACD-50. SEV infusion rate remained constant. SEV reflection was higher (SRI: ACD-100 vs. ACD-50, TV 5 ml/kg: 95.29 ± 6.45 vs. 85.54 ± 11.15, p = 0.001; 7 ml/kg: 93.42 ± 6.55 vs. 88.77 ± 12.26, p = 0.003). BIS was significantly lower when using the higher TV (60.91 ± 9.99 vs. 66.57 ± 8.22, p = 0.012), although this difference was not clinically relevant. During postoperative sedation, the use of ACD-50 significantly reduced CO2 retention. SEV reflection was slightly reduced. However, patients remained sufficiently sedated without increasing SEV infusion.

Saving sevoflurane: Automated gas control can reduce consumption of anesthetic vapor by one-third in pediatric anesthesia.

BACKGROUND: Many modern anesthetic machines offer automated control of anesthetic vapor. The user simply sets a desired end-tidal concentration and the machine will manipulate the vaporizer and gas flow rates to obtain and maintain the preset target. Greater efficiency, and more accurate delivery of anesthetic vapor have been documented across multiple machines within the adult setting however, there is little evidence for their use in children. AIMS: The aim of this study was to compare the consumption of sevoflurane using the Maquet Flow-i anesthesia machine (Maquet, Solna, Sweden) in automatic gas control mode vs manual mode in pediatric anesthesia. The primary outcome measure is rate of sevoflurane use. METHOD: Data logs were collected from our three Maquet Flow-i anesthesia machines over a 4-week period. We compared the rate of sevoflurane use when in manual mode vs cases where the automatic gas control mode was used. We also examined each automatic gas control case to determine whether percentage of anesthesia time in this mode correlated significantly with average rate of sevoflurane consumption. RESULTS: Sevoflurane was the primary anesthetic used in 220 cases, comprising over 230 hours of anesthesia time. Of these, 36 cases were identified as automatic gas control cases and 184 as manual cases. Consumption of sevoflurane liquid in mL/min was significantly lower in automatic gas control cases (median 0.46, IQR 0.32-0.72 mL/min for automatic gas control; median 0.82, IQR 0.62-1.17 mL/min for manual; P < 0.001 by Wilcoxon Rank Sum test). For a case of median duration (49 minutes), average rate of sevoflurane liquid consumption was 0.54 mL/min for automatic gas control cases vs 0.81 mL/min for manual cases, a reduction of 33% (bootstrapped 95% CI 0.21-0.61 mL/min, P < 0.001). CONCLUSION: Maquet's Flow-i automatic gas control mode reduced use of sevoflurane an average of one-third in a pediatric anesthesia setting.

Low-flow anaesthesia with a fixed fresh gas flow rate.

During the wash-in period in low flow anaesthesia (LFA), high fresh gas flow is used to achieve the desired agent concentration. In this study, we aimed to evaluate the safety of fixed 1 L/min fresh gas flow desflurane anaesthesia in both the wash-in and maintenance periods in patients including the obese ones. 104 patients undergoing surgery under general anaesthesia were included. After endotracheal intubation, fresh gas flow was reduced to 1 L/min and the desflurane vaporizer was set at 18%. The time from opening the vaporizer to end-tidal desflurane concentration reaching 0.7 MAC was recorded (MAC 0.7 time). Throughout the surgery, hemodynamic variables, FIO2, MAC and BIS values were observed. MAC 0.7 time, BIS and MAC values at the start of surgery, number of adjustments in vaporizer settings, desflurane consumption were recorded. The average MAC 0.7 time was 2.9 ± 0.5 min. MAC and BIS values at the start of the surgery were 0.7 (0.6-0.8) and 39 ± 8.5 respectively. No individual patient had a BIS value above 60 throughout the surgery. Hemodynamic variables were stable and FIO2 did not fall below 30% in any patient. The number of adjustments in vaporizer settings was 56. Average desflurane consumption was 0.33 ± 0.05 mL/min. We demonstrated that LFA without use of initial high fresh gas flow during the wash-in period is an effective, safe and economic method which is easy to perform.

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.

Halving the Volume of AnaConDa: Evaluation of a New Small-Volume Anesthetic Reflector in a Test Lung Model.

BACKGROUND: Volatile anesthetics are increasingly used for sedation in intensive care units. The most common administration system is AnaConDa-100 mL (ACD-100; Sedana Medical, Uppsala, Sweden), which reflects volatile anesthetics in open ventilation circuits. AnaConDa-50 mL (ACD-50) is a new device with half the volumetric dead space. Carbon dioxide (CO2) can be retained with both devices. We therefore compared the CO2 elimination and isoflurane reflection efficiency of both devices. METHODS: A test lung constantly insufflated with CO2 was ventilated with a tidal volume of 500 mL at 10 breaths/min. End-tidal CO2 (EtCO2) partial pressure was measured using 3 different devices: a heat-and-moisture exchanger (HME, 35 mL), ACD-100, and ACD-50 under 4 different experimental conditions: ambient temperature pressure (ATP), body temperature pressure saturated (BTPS) conditions, BTPS with 0.4 Vol% isoflurane (ISO-0.4), and BTPS with 1.2 Vol% isoflurane. Fifty breaths were recorded at 3 time points (n = 150) for each device and each condition. To determine device dead space, we adjusted the tidal volume to maintain normocapnia (n = 3), for each device. Thereafter, we determined reflection efficiency by measuring isoflurane concentrations at infusion rates varying from 0.5 to 20 mL/h (n = 3), for each device. RESULTS: EtCO2 was consistently greater with ACD-100 than with ACD-50 and HME (ISO-0.4, mean ± standard deviations: ACD-100, 52.4 ± 0.8; ACD-50, 44.4 ± 0.8; HME, 40.1 ± 0.4 mm Hg; differences of means of EtCO2 [respective 95% confidence intervals]: ACD-100 - ACD-50, 8.0 [7.9-8.1] mm Hg, P < .001; ACD-100 - HME, 12.3 [12.2-12.4] mm Hg, P < .001; ACD-50 - HME, 4.3 [4.2-4.3] mm Hg, P < .001). It was greatest under ATP, less under BTPS, and least with ISO-0.4 and BTPS with 1.2 Vol% isoflurane. In addition to the 100 or 50 mL "volumetric dead space" of each AnaConDa, "reflective dead space" was 40 mL with ACD-100 and 25 mL with ACD-50 when using isoflurane. Isoflurane reflection was highest under ATP. Under BTPS with CO2 insufflation and isoflurane concentrations around 0.4 Vol%, reflection efficiency was 93% with ACD-100 and 80% with ACD-50. CONCLUSIONS: Isoflurane reflection remained sufficient with the ACD-50 at clinical anesthetic concentrations, while CO2 elimination was improved. The ACD-50 should be practical for tidal volumes as low as 200 mL, allowing lung-protective ventilation even in small patients.

Environmental safety: Air pollution while using MIRUS™ for short-term sedation in the ICU.

BACKGROUND: MIRUS™ is a device for target-controlled inhalational sedation in the ICU in combination with use of isoflurane, or sevoflurane, or desflurane. The feasibility of this device has recently been proven; however, ICU staff exposure may restrict its application. We investigated ICU ambient room pollution during daily work to estimate ICU personnel exposure while using MIRUS™. METHODS: This observational study assessed pollution levels around 15 adult surgical patients who received volatile anaesthetics-based sedation for a median of 11 hours. Measurements were performed by photoacoustic gas monitoring in real-time at different positions near the patient and in the personnel's breathing zone. Additionally, the impact of the Clean Air™ open reservoir scavenging system on volatile agent pollution was evaluated. RESULTS: Baseline concentrations [ppm] during intervention and rest periods were isoflurane c¯mean = 0.58 ± 0.49, c¯max = 5.72; sevoflurane c¯mean = 0.22 ± 0.20, c¯max = 7.93; and desflurane c¯mean = 0.65 ± 0.57, c¯max = 6.65. Refilling MIRUS™ with liquid anaesthetic yielded gas concentrations of c¯mean = 2.18 ± 1.48 ppm and c¯max = 13.03 ± 9.37 ppm in the personnel's breathing zone. Air pollution in the patient's room was approximately five times higher without a scavenging system. CONCLUSION: Ambient room pollution was minimal in most cases, and the measured values were within or below the recommended exposure limits. Caution should be taken during refilling of the MIRUS™ system, as this was accompanied by higher pollution levels. The combined use of air-conditioning and gas scavenging systems is strongly recommended.

Randomized-controlled trial of parent-led exposure to anesthetic mask to prevent child preoperative anxiety.

PURPOSE: To examine the efficacy of parent-directed anesthetic mask exposure and shaping practice to prevent child preoperative anxiety, with a specific focus on timing of exposure. METHODS: This randomized-controlled trial included 110 children ages four to seven years undergoing day surgery dental procedures and their parents. Families were randomly assigned to one of three groups: 1) parent-directed mask exposure/shaping practice at least three times in the week prior to surgery (Group 1); 2) parent-directed mask exposure/shaping practice at least once on the day of surgery (Group 2); 3) no exposure prior to induction (Group 3). Child anxiety was observer-rated using the modified Yale Preoperative Anxiety Scale during the day surgery experience, and induction compliance was observer-rated using the Induction Compliance Checklist. RESULTS: Results demonstrated significant differences in observer-rated child anxiety at anesthetic induction across groups. Group 2 demonstrated significantly lower observer-rated anxiety than Group 3 with a medium effect, F(1, 71) = 4.524, P = 0.04, η p 2 = 0.06. A significant interaction was observed between these two groups over time (i.e., admission to anesthesia induction), F(1, 71) = 4.365, P = 0.04, η p 2 = 0.06 (i.e., small to medium effect). Group 2 demonstrated the best anesthesia induction compliance (i.e., significantly lower scores than Group 3, P = 0.04). CONCLUSION: Timing of the delivery of mask exposure (i.e., on the day of surgery) to address child preoperative anxiety and induction compliance in the day surgery setting may be an important consideration. The current results inform the integration of this simple, effective strategy into practice.

RéSUMé: OBJECTIF: Examiner l'efficacité d'une exposition au masque anesthésique menée par un parent et détermination d'une pratique visant à prévenir l'anxiété préopératoire de l'enfant en se concentrant spécifiquement sur le moment de l'exposition. MéTHODES: Cette étude randomisée contrôlée a inclus 110 enfants âges de quatre à sept ans subissant une procédure dentaire en chirurgie d'un jour et leurs parents. Après randomisation, les familles ont été assignées à l'un des trois groupes suivants : 1) exposition au masque/pratique de modelage comportemental dirigée par le parent au moins trois fois dans la semaine précédant l'intervention (Groupe 1); 2) exposition au masque/pratique de modelage comportemental dirigée par le parent au moins une fois le jour de la chirurgie (Groupe 2); 3) aucune exposition avant l'induction (Groupe 3). L'anxiété de l'enfant a été évaluée par un observateur utilisant l'échelle mYPAS (échelle modifiée d'anxiété préopératoire de Yale) au cours de l'expérience le jour de la chirurgie et la conformité de l'induction a été évaluée par un observateur utilisant l'ICC (liste de vérification de la conformité de l'induction). RéSULTATS: Les résultats ont mis en évidence des différences significatives entre les groupes sur l'anxiété de l'enfant évaluée par un observateur au moment de l'induction anesthésique. Le Groupe 2 a présenté une anxiété évaluée par l'observateur significativement inférieure à celle du Groupe 3 avec un effet médian F (1, 71) = 4,524, P = 0,04, η P 2 = 0,06. Une interaction significative a été observée entre ces deux groupes au fil du temps (c'est-à-dire entre l'admission et l'induction de l'anesthésie), F (1, 71) = 4,365, P = 0,04, η P 2 = 0,06 (soit un effet petit à moyen). Le Groupe 2 a manifesté la meilleure conformité de l'induction de l'anesthésie (c'est-à-dire, des scores significativement inférieurs au Groupe 3, P = 0,04). CONCLUSION: Il peut être important de tenir compte du moment de l'exposition au masque (c'est-à-dire le jour de l'intervention) pour répondre à l'anxiété préopératoire de l'enfant et à la conformité de l'induction dans le cadre de la chirurgie d'un jour. Les résultats actuels renseignent sur l'intégration de cette stratégie simple et efficace dans la pratique.