Parasympathetic tone, cardiovascular variables, and behavioral alterations in conscious horses before and after castration and during anesthesia: A pilot study.

Association of the dose of maternal general anaesthesia during Caesarean delivery with 5-minute Apgar scores: a retrospective single centre cohort study.

Background: This study aimed to compare the effects of equipotent doses (one minimum alveolar concentration) of sevoflurane and desflurane on respiratory mechanics, haemodynamics and oxygenation in patients undergoing spinal surgery in the prone position. Methods: Fifty patients were randomised to receive either sevoflurane (n = 25) or desflurane (n = 25). Respiratory parameters (dynamic compliance (Cdyn); peak (Ppeak), mean (Pmean) and plateau (Pplateau) airway pressures; driving pressure (∆P); tidal volume; and dead space), haemodynamic parameters (heart rate (HR) and systolic, mean and diastolic arterial pressures) and oxygenation parameters were recorded intraoperatively at baseline, after prone positioning, during surgery, and after returning to the supine position. Results: Prone positioning led to significant increases in Ppeak and reductions in Cdyn in both groups (p < 0.05). Although Ppeak, Pmean, Pplateau and ∆P fluctuated intraoperatively, no intergroup differences were detected (p > 0.05). After returning to the supine position, respiratory mechanics approached baseline in both groups. Oxygenation (arterial oxygen pressure), ventilation (arterial carbon dioxide pressure), end-tidal carbon dioxide, and pH remained stable and comparable. Sevoflurane was associated with slightly greater decreases in arterial pressures, whereas HR was similar between groups. Conclusions: Both desflurane and sevoflurane maintained stable intraoperative respiratory mechanics, oxygenation, and haemodynamics in patients without pulmonary disease. Prone positioning increased Ppeak and decreased Cdyn similarly in both groups. Both agents appear safe for spinal surgery in the prone position. Clinical Trial Registration: This study was registered at ClinicalTrials.gov (NCT06118489).

BackgroundDesflurane is a widely used inhalational anesthetic known for its advantageous properties in clinical settings. This study aimed to investigate the effects of desflurane inhalation on male reproductive hormones, testicular tissue integrity, and sperm morphology in a rat model.MethodsThirty male rats were allocated into six experimental groups:Control group (C): Administered 2 L/min of O₂ for 18 minutes daily over seven days.Group D1: Exposed to 1 minimum alveolar concentration (MAC) of desflurane and 2 L/min of O₂ for 18 minutes daily over seven days.Group D2: Received the same treatment as Group 1 for seven days, followed by a seven-day recovery period without intervention.Group D3: Administered 1 MAC desflurane and 2 L/min of O₂ for 18 minutes daily over 14 days.Group D4: Received the same treatment as Group 3 for 14 days, followed by a seven-day recovery period without intervention.Group D5: Administered the same treatment as Group 3 for 14 days, followed by a 14-day recovery period without intervention.Biochemical analyses were conducted to measure serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, and inhibin B. Histopathological evaluations were performed to assess testicular tissue integrity, and sperm morphology was examined to identify abnormalities.ResultsSignificant histopathological damage was observed in all experimental groups compared to the control group (p < 0.05). The proportion of morphologically abnormal spermatozoa was significantly higher in Groups D2, D3, D4, and D5 compared to the control group (p = 0.030, p = 0.002, p < 0.001, and p = 0.016, respectively). Compared to the control group, serum FSH levels showed a slight decrease across desflurane-exposed groups (ranging from −1.4% to +4.02%). The LH levels demonstrated a gradual reduction of approximately 0.32%–7.38%, while serum testosterone concentrations increased markedly, reaching up to 178% of the control level in the D4 group. Inhibin-B levels exhibited a progressive elevation of nearly 23–95% compared to control group. ConclusionChronic inhalation of desflurane, a modern inhalational anesthetic, was found to adversely affect testicular histology, sperm morphology, and the regulation of male reproductive hormones in rats. These findings highlight potential reproductive toxicity associated with prolonged desflurane exposure.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12871-026-03668-4.

BackgroundIntraoperative EEG provides a noninvasive window into cortical dynamics under anesthesia, but conventional spectral analysis cannot capture nonstationary modulation patterns linked to nociceptive processing. This study applied Holo‐Hilbert spectral analysis (HHSA) to characterize cross‐frequency modulation patterns in relation to the Surgical Pleth Index (SPI) during general anesthesia.MethodsFrontal EEG from 134 female patients undergoing gynecologic surgery was analyzed. Ten‐minute segments were first examined to define canonical modulation structures, followed by one‐minute epochs synchronized with SPI values to assess dynamic changes. HHSA decomposed each epoch into amplitude modulation patterns across carrier frequencies (1/64–64 Hz). Group comparisons between pain and no‐pain epochs were performed using t‐tests with Bonferroni correction. A linear mixed‐effects model evaluated the effects of SPI, minimum alveolar concentration (MAC), heart rate (HR), and mean arterial pressure (NIBP‐m) on alpha‐band modulation (8–16‐Hz carrier modulated by 3–8‐Hz amplitude).ResultsHHSA revealed two dominant cross‐frequency interactions within the alpha‐carrier band (8–16 Hz): one modulated by 3–6‐Hz (high‐delta to theta) and another by 1–2‐Hz (low‐delta) oscillations, indicating layered modulation under anesthesia. During nociceptive states (SPI > 60), modulation power increased in the alpha and high‐delta bands, while theta and low‐delta modulation weakened. Alpha‐band modulation power rose with SPI and declined with MAC.ConclusionsHHSA revealed distinct cross‐frequency modulation patterns reflecting the cortical balance between nociception and analgesia. Alpha‐band modulation serves as a physiologically grounded EEG marker for individualized nociception monitoring under general anesthesia.

Abstract Background and Aims: Previous studies found that low-flow sevoflurane anesthesia in respiratory mechanics is comparable with higher flow during laparoscopic surgery, but metabolic flow has not been studied adequately. The study compares the effect of metabolic flow with the low-flow technique on respiratory mechanics during laparoscopic procedures. Material and Methods: Sixty adult patients of either sex, American Society of Anesthesiologists physical status I-II scheduled for laparoscopic surgery of &lt;3 h were randomly assigned into group M: metabolic (n = 30) and group L: low-flow anesthesia (n = 30). Both groups received fresh gas flow (FGF) of 6 L/min of oxygen, air, and sevoflurane until they attained a minimum alveolar concentration (MAC) of 1; FGF was changed to 1 L/min in group L. In group M, the FGF was changed to estimate the metabolic flow of oxygen (Brody’s formula) plus the leak detected during the pre-use check. The delivered FiO 2 was maintained above 50%, and The dial concentration of sevoflurane was adjusted to maintain a target MAC-1 throughout the procedure in both groups. The primary objective was to compare postoperative forced vital capacity (FVC) after achieving a Modified Aldrete Score of ≥9. The secondary objectives included comparing arterial blood gas (ABG) parameters, hemodynamic parameters, and sevoflurane consumption. Results: There was no statistically significant difference in the FVC, ABG, and hemodynamic parameters between the two groups pre- (T1) and postoperatively (T2, T3, T4). There was a statistically significant decrease in sevoflurane consumption ( P = &lt;0.001) in the metabolic-flow group. Conclusions: The effects of metabolic-flow anesthesia on pulmonary mechanics and gas exchange were similar to those of the low-flow anesthesia technique.

Minimum Alveolar Concentration Ratio Factors: Reply.

ACE Question: Factors in Minimum Alveolar Concentration

Volatile anesthetics representa relevant yet largely avoidable source of greenhouse gas emissions in the healthcare system. In Germany, their use accounts for approximately69 kt of CO2 equivalents annually. While desflurane is used in only about3% of inhalation anesthesia procedures, it is responsible for more than50% of the associated emissions due to its extremely high global warming potential. Modelling studies indicate that complete substitution of desflurane with sevoflurane would reduce total emissions by approximately53%; replacing isoflurane as well would increase the reduction to65%. From a clinical perspective, desflurane offers no proven advantage over sevoflurane with respect to patient safety or postoperative outcomes. Isoflurane likewise shows no clinical superiority. This creates substantial scope for substitution without compromising quality of care. Under minimum alveolar concentration (MAC)-adjusted conditions, desflurane causes an approximately34-fold higher global warming per anesthesia hour than sevoflurane. The contrast is even greater when compared to total intravenous anesthesia (TIVA). Of particular relevance is the short-term climate impact. Due to its high radiative efficiency, desflurane exerts most of its warming effect within a few decades, precisely the critical period up to2050. In addition, volatile anesthetics contribute to environmental contamination with persistent perfluoroalkyl and polyfluoroalkyl substances (PFAS), posing potential long-term risks to ecosystems and human health. Eliminating desflurane requires no new infrastructure, is economically rational and can be implemented immediately. It hence represents a rare opportunity in the healthcare system to achieve rapid and substantial emission reductions through a simple clinical decision, while maintaining patient safety and quality of care.

Volatile anesthetics representa relevant yet largely avoidable source of greenhouse gas emissions in the healthcare system. In Germany, their use accounts for approximately69 kt of CO2 equivalents annually. While desflurane is used in only about3% of inhalation anesthesia procedures, it is responsible for more than50% of the associated emissions due to its extremely high global warming potential. Modelling studies indicate that complete substitution of desflurane with sevoflurane would reduce total emissions by approximately53%; replacing isoflurane as well would increase the reduction to65%. From a clinical perspective, desflurane offers no proven advantage over sevoflurane with respect to patient safety or postoperative outcomes. Isoflurane likewise shows no clinical superiority. This creates substantial scope for substitution without compromising quality of care. Under minimum alveolar concentration (MAC)-adjusted conditions, desflurane causes an approximately34-fold higher global warming per anesthesia hour than sevoflurane. The contrast is even greater when compared to total intravenous anesthesia (TIVA). Of particular relevance is the short-term climate impact. Due to its high radiative efficiency, desflurane exerts most of its warming effect within a few decades, precisely the critical period up to2050. In addition, volatile anesthetics contribute to environmental contamination with persistent perfluoroalkyl and polyfluoroalkyl substances (PFAS), posing potential long-term risks to ecosystems and human health. Eliminating desflurane requires no new infrastructure, is economically rational and can be implemented immediately. It hence represents a rare opportunity in the healthcare system to achieve rapid and substantial emission reductions through a simple clinical decision, while maintaining patient safety and quality of care.

This study aimed to compare two different sevoflurane formulations (Sevones® and Sevorane®) under low-flow anesthesia in terms of time to 1 Minimum Alveolar Concentration (MAC), agent consumption and uptake, emergence profile, and anesthesia-related complications. This retrospective observational study was conducted at Sakarya University Training and Research Hospital, Türkiye. A total of 89 female patients undergoing elective gynecologic surgery under general anesthesia with low-flow sevoflurane (≤ 1L/min) were included. Patients received either Sevones® (n = 46) or Sevorane® (n = 43). Standardized anesthetic induction with propofol and rocuronium was followed by low-flow sevoflurane maintenance. The primary outcome was time to reach 1 MAC. Secondary outcomes included agent consumption and uptake during induction and maintenance, emergence characteristics, intraoperative hemodynamic and PSI trends, and anesthesia-related complications. Statistical comparisons were performed using t-test, Mann-Whitney U, and chi-square tests as appropriate. Time to reach 1 MAC was similar between Sevones® and Sevorane® groups (198.26 ± 41.1s vs. 205.63 ± 51.2s; p = 0.455). Agent consumption and uptake during induction were comparable. Total agent uptake was significantly higher in the Sevones® group (16.63 ± 5.32 mL vs. 13.49 ± 7.45 mL; p = 0.024), while total agent consumption showed no significant difference. Emergence times, PSI trends, and complication rates were similar between groups. Both Sevones® and Sevorane® demonstrated comparable pharmacokinetic and pharmacodynamic profiles under low-flow anesthesia. The findings support their safe and effective use during elective gynecologic surgery. Not applicable.

Abstract Background: Sevoflurane is usually administered according to the minimum alveolar concentration. Age is an important variable affecting the minimum alveolar concentration and it should be kept in mind that two individuals of the same chronologic age may have different metabolic ages. The purpose of this study is to evaluate the relationship between metabolic age, chronological age and sevoflurane consumption in patients with sufficient depth of anesthesia. Methods: Bioelectrical impedance analysis of 79 patients aged 18-65 years, chronological age, metabolic age and other metabolic parameters were recorded. To standardize the relationship between sevoflurane consumption and chronological age and metabolic age, patients were divided into three groups using the percentage age difference formula; Group A; age difference 11.7%. Results: The study included 79 patients, 29.1% of whom were women. The mean chronologic and metabolic ages of the patients were 31.29 ± 11.9 and 30.42 ± 12.89 years, respectively. A significant difference was seen between chronologic and metabolic age and total sevoflurane consumption (p=0.006; p=0.007) and a weak negative correlation was observed (r= -0.304; r=-0.301). When the sevoflurane consumption amounts of the groups were compared, a notable difference was observed among the three groups (p

This study compared automatic gas control (AGC) mode with manual minimal-flow and manual medium-flow techniques in elective breast surgery, evaluating sevoflurane consumption, cost, hemodynamics, and recovery. Following ethics approval, 90 American Society of Anaesthesiologists I-II patients (age 18-65 years) undergoing elective breast surgery were randomized to AGC mode (Group AGC, n = 30), manual minimal-flow control (Group ManCo, n = 30), or manual medium-flow control (Group ModFA, n = 30). All received standard induction after preoxygenation, with maintenance via sevoflurane and remifentanil infusion in a mixture of oxygen and medical air. After reaching a minimum alveolar concentration of 1.0, sevoflurane was adjusted to maintain a bispectral index of 40-60. Mean arterial pressure (MAP), heart rate, peripheral capillary oxygen saturation, bispectral index, inspired sevoflurane fractions and expired sevoflurane fraction, end-tidal carbon dioxide, temperature, and instantaneous sevoflurane consumption were recorded pre-induction and every 15 minutes. Extubation time, recovery time, surgery duration, and total anaesthesia time were documented. Total sevoflurane consumption and cost were calculated postoperatively. Sevoflurane consumption and related costs were significantly lower in Group AGC versus Groups ManCo and ModFA (both P <0.001) and lower in Group ManCo than in Group ModFA (P <0.001). MAP and recovery times did not differ significantly among groups (P >0.05). Pre-extubation temperature was higher in Group AGC compared to Group ManCo (P=0.014) and Group ModFA (P=0.002). Extubation time was longer in Group ManCo versus Groups AGC and ModFA (P <0.001). AGC mode significantly reduces sevoflurane consumption and cost compared to both manual minimal-flow and manual medium-flow techniques, without adversely affecting hemodynamics or recovery.

Introduction: Deep brain stimulation (DBS) is an established treatment for Parkinson’s disease (PD). The traditional method for accurate implantation is awake microelectrode recordings (MERs) to map out the borders of the target nucleus. However, a significant portion of patients are unable to tolerate awake surgical procedures. Asleep MER techniques under different general anesthesia regimens have been described with variable effects on recording quality and required a lower inhaled sevoflurane level to obtain single unit recordings. Hence, a reliable method for asleep MER mapping is needed without compromising patient safety and comfort. We aimed to assess the feasibility and quality of basal ganglia MER under general anesthesia using inhalational agents including adding nitrous oxide as an adjunct to sevoflurane (N2O-GA). Methods: This study retrospectively examined PD patients undergoing DBS implantation targeting either the subthalamic nucleus (STN) or the globus pallidus internus (GPi) at a single center. Anesthetic data on end-tidal (ET) sevoflurane and nitrous oxide, with the derived minimum alveolar concentration (MAC) were captured during the time of MER mapping. We evaluated the feasibility of identifying target nuclei borders, the quality of neuronal unit isolation, and the physiological dimensions of the targeted nuclei. We calculated the concordance between the nuclei sizes based on MER mapping and imaging. We also reported the firing characteristics of isolated units. Results: We identified 18 patients (34 nuclei) who underwent STN (n = 11) and GPi (n = 7) DBS implantation. Background activity changes were reliable in all patients for border identification. The length of the tract identified by MER was highly concordant with the anatomical tract length identified by postoperative imaging (concordance correlation coefficient: 0.84, p < 0.001). Firing in both nuclei showed higher bursting rates. Pallidal cells showed typical firing patterns with “pauser” cells in the GPe and continuous firing in the GPi. No complications were observed during follow-up. A total of 16 patients had MER data available for offline analysis. We identified 516 units (single/multi) across MER 28 tracts (STN = 284, GP = 232). In the 14 patients received the N2O-GA, anesthetic depth was maintained at 0.97 ± 0.06 MAC, compared to 0.525 ± 0.04 MAC in the sevoflurane-only cases. Conclusion: MER under N2O-GA is feasible for DBS target nuclei identification for both STN and GPi and offers a safe and accurate surgical approach for PD patients unable to tolerate awake mapping.

The potency of propofol is measured by its Cp50 value, which is the plasma concentration required to suppress a motor response in 50% of patients during surgical incisions. This Cp50 value can be affected by the concurrent use of other drugs, including opioids, benzodiazepines, or lidocaine. Pregabalin, a medication commonly administered as preoperative premedication, provides mild sedative and anxiolytic effects. Although pregabalin has the potential to reduce the minimum alveolar concentration (MAC) of sevoflurane, its effects on propofol-based anesthesia have not been conclusively studied. Thus, we designed a placebo-controlled, double-blind clinical trial to evaluate the impact of pregabalin on the Cp50 of propofol. Eighty female patients who underwent breast surgery participated in this study. They received either a placebo or 300 mg of pregabalin 2 hours before anesthesia induction. Propofol was administered as the sole anesthetic agent, delivered continuously via a target-controlled infusion (TCI) pump using the Schnider model, without the addition of opioids or other analgesics. Patients in both groups were administered different target effect-site propofol concentrations, and their motor responses to standardized skin incisions were determined. The Cp50 value of propofol was estimated using a logistic regression model, and the results were re-evaluated using bootstrap methods. A significant difference in propofol Cp50 values was found between the placebo and pregabalin groups. Using the delta method, the Cp50 value of propofol was estimated to be 16.9 μg/mL (95% confidence interval [CI], 15.1-18.8) in the placebo group and 9.4 μg/mL (95% CI, 4.46-14.3) in the pregabalin group. Secondary outcome measures revealed significantly decreased opioid consumption and pain levels in the recovery area in the pregabalin group compared to the placebo group. This study demonstrated that pretreatment with 300 mg pregabalin significantly reduced the Cp50 value of propofol by 44%, as calculated using the delta method. When 300 mg of pregabalin is administered before anesthesia and propofol is used for maintenance via TCI, a lower target effect-site concentration might be sufficient. Additionally, pregabalin premedication has the potential to decrease postoperative pain and opioid consumption.

The carbon footprint of propofol is less than that of sevoflurane per minimum alveolar concentration hour equivalent of drug, but there are justifiable concerns about the amount of clinical waste generated duringtotal intravenous anaesthesia (TIVA), especially in the context of shorter procedures. The aim of this study was to assess the carbon footprint of inhalational sevoflurane anaesthesia vs. TIVA with propofol and remifentanil, including all the consumables used, over the first 6 h of general anaesthesia in adult patients. A hybrid approach was used to model 10 scenarios: intravenous induction followed by inhalational sevoflurane maintenance with five levels of sevoflurane consumption; and five TIVA scenarios with different combinations of low, moderate and high doses of propofol and remifentanil. For the first 22 min, the median consumption sevoflurane scenario had a lower estimated carbon footprint than all TIVA scenarios, beyond which all TIVA scenarios had a lower carbon footprint. Beyond 44 min, all sevoflurane scenarios had higher carbon footprints than all the TIVA scenarios. For every hour of general anaesthesia beyond 22 min, the carbon footprint of the moderate dose TIVA scenario increased by 0.04-0.60 kgCO2e.h-1, compared with 4.01 kgCO2e.h-1 for the median consumption sevoflurane scenario. Hotspot analysis of the moderate dose TIVA and median consumption sevoflurane scenarios showed that the consumables used in TIVA contributed most to the estimated overall carbon footprint of this technique (50.9-60.4%), followed by drugs (39.6-45.4%). In the sevoflurane scenario, sevoflurane was the greatest contributor to the carbon footprint, eventually being responsible for 99.5% of the total footprint at 360 min. Adopting TIVA for appropriate cases lasting longer than 22 min will reduce the carbon footprint of general anaesthesia compared with median consumption of sevoflurane general anaesthesia. Using low fresh gas flows or end-tidal control reduces the carbon footprint of inhalational general anaesthesia.

Background:Perioperative intravenous (IV) lignocaine infusion has a minimum alveolar concentration sparing effect, and this study was designed to investigate the impact of IV lignocaine infusion on the intraoperative end-tidal desflurane (Et-Des) concentration required to maintain the Bispectral Index Scale (BIS) values between 40 and 60.Methods:Forty-eight patients were recruited for laparoscopic cholecystectomy, appendicectomy, or ovarian cystectomy. They were randomly assigned to Group A, who received a bolus of 1.5 mg kg⁻1 of 2% lignocaine hydrochloride over 3 minutes, followed by an IV infusion of 1 mg kg⁻1 h⁻1 until skin closure, and Group B, who received an equal volume of normal saline. Baseline BIS values, heart rate, and mean arterial pressure were recorded before induction of anesthesia and subsequently every 10 minutes until skin closure. Et-Des concentration, hemodynamic changes, BIS, minimum alveolar concentration, the dose of fentanyl administered, and the amount and cost of desflurane used between the 2 groups were analyzed.Results:Et-Des concentration in Group A (4.3% ± 0.45%) was significantly lower than in Group B (5.3% ± 0.56%, P < .001). The cost of desflurane was significantly reduced in Group A than in Group B (Ringgit Malaysia: 35.79 ± 7.43 vs Ringgit Malaysia: 46.37 ± 9.75, P < .001). Both groups’ heart rate and mean arterial pressure showed no significant differences (P = .484 and 0.619, respectively).Conclusion:Intravenous lignocaine infusion reduces the Et-Des concentration, amount, and cost required to maintain the BIS value at 40 to 60 without significant hemodynamic changes or side effects in laparoscopic abdominal surgery. The usage of intravenous lignocaine infusion as adjunct to anesthesia is feasible to reduce anesthetic agent requirement.

PurposeThe study aims to retrospectively examine performance of general anesthesia in percutaneous radiofrequency ablation (RFA) of renal cell carcinoma (RCC) and to assess the long-term outcomes.Materials and MethodsBetween September 2012 and August 2019, 87 patients (68 males and 19 females; mean age, 61 years) with biopsy-proven T1a RCC underwent computed tomography-guided RFA under general anesthesia. Anesthetic time, minimal alveolar concentration (MAC), and post-anesthetic complications were recorded. Primary effectiveness and local tumor progression (LTP)-free and metastasis-free survival rates were calculated. Major complications following RFA were assessed. A Kaplan–Meier analysis was used to determine the long-term survival rate.ResultsGeneral anesthesia and RFA were performed with 100% technical success. The mean time of general anesthesia was 127 minutes (range, 63–248 minutes). The mean MAC was 0.88±0.15. There was no complication related to general anesthesia. Primary effectiveness was 100%, and the 5-year LTP-free or metastasis-free rate was 97.7% (85/87). One major RFA complication occurred in a patient with ureter stricture that was detected during a follow-up examination.ConclusionsLow-MAC general anesthesia during RFA procedures is appropriate for precise RCC targeting. This type of pain control could influence the long-term outcomes of RCC patients.

The aim of this study was to determine the feasibility of intraoperative motor function monitoring using motor-evoked potential (MEP) in combination with low-concentration sevoflurane during propofol anesthesia. This study was a prospective, non-randomized trial that included 38 patients undergoing neurosurgery. MEP were performed under age-adjusted 0, 0.2, and 0.5 minimum alveolar concentrations (MACs) of additional sevoflurane inhalation on propofol anesthesia sequentially. MEP monitoring positive rate, amplitude, latency, and physiological variables were compared between the sections. The percentages of monitoring positive rate with additional 0.2 and 0.5 MACs of sevoflurane were 86.8% and 36.8%, respectively [p < 0.001, 0.5 MAC; relative risk = 0.424, 95% confidence interval (CI) 0.275-0.655]. The amplitudes and latency were significantly decreased and prolonged with sevoflurane administration and increasing MAC. Areas under the curve for 0.2 and 0.5 MACs of sevoflurane were 0.976 (95% CI 0.923-1.000) and 0.857 (95% CI 0.740-0.974), respectively. The best cutoff values were 462.3µV and 820.6µV, respectively. Results suggested that combined anesthetic management can be performed if the amplitude is higher than the cutoff values.

Background and Aims:The age-dependent decline in sevoflurane’s minimum alveolar concentration is well established. However, the relationship between ageing and its hypnotic potency at the effect-site concentration (Ceff) remains unclear. This study aimed to evaluate the impact of ageing on sevoflurane’s hypnotic potency and induction kinetics during the wash-in period.Methods:This prospective observational study enroled 83 female patients stratified by age into four decades: 30–39, 40–49, 50–59, and 60–69 years. Anaesthesia was induced using 5% sevoflurane in a non-rebreathing manner. We continuously recorded bispectral index (BIS) values and end-tidal sevoflurane concentrations during the 4 min wash-in period, with Ceff values calculated through pharmacokinetic modelling. Subsequently, the end-tidal concentration was maintained at 1.5% for 20 min (10 min equilibration + 10 min stabilisation) at 2 L/min to achieve a cerebral steady-state, and the final stabilised BIS value was calculated. One-way ANOVA with Bonferroni post-hoc correction or Kruskal-Wallis test was used to compare continuous variables. Pearson’s Chi-square test was used to compare categorical variables, with the significant difference set at P < 0.05.Results:During the wash-in period, the 60–69-year group exhibited a prolonged time from awakening to BIS 50 compared to younger cohorts (P < 0.05 or < 0.01). Ceff values exhibited progressively delayed kinetics with increasing age, but Ceff values of sevoflurane at BIS 50 were not different across the four age groups (P > 0.05). At a steady state of 1.5% sevoflurane anaesthesia, the intergroup analysis revealed no significant variations in BIS values.Conclusion:The hypnotic potency of sevoflurane is preserved among female patients aged 30–69 years despite delayed induction kinetics in older individuals.