Minimum Alveolar Concentration Research Articles

Remifentanil stabilizes hemodynamics with modulating subthalamic beta oscillation during deep brain stimulation.

General anesthesia is a promising method for advanced Parkinson's disease patients unable to tolerate awake deep brain stimulation (DBS) surgery. However, anesthetic agents must be kept at relatively low levels to preserve the quality of intraoperative microelectrode recordings, which can lead to unstable hemodynamic conditions. Remifentanil, with its sedative and analgesic properties, could offer a solution. This study retrospectively analyzed microelectrode recordings of the subthamic nucleus (STN) and hemodynamic responses in patients with Parkinson's disease who received deep brain stimulation surgery under controlled volatile anesthesia with/without remifentanil infusion. From October 2017 to June 2019, 24 patients with Parkinson's disease who received bilateral subthalamic deep brain stimulation surgery in Hualien Tzu Chi Hospital with (n = 12) or without remifentanil infusion (n = 12) were enrolled in this study. We conducted a comprehensive spike analysis, examining frequency, inter-spike interval properties, modified burst index, modified pause index, and modified pause ratio. Additionally, we performed spike frequency spectrum analysis to investigate oscillatory activity in high-frequency, multi-unit, and single-unit neuronal activity. Our findings revealed no differences in STN firing characteristics, while a significant decrease in high beta power was observed in multi-unit activity in the remifentanil group. Notably, nine patients in the non-remifentanil group required additional nicardipine, whereas none in the remifentanil group did. Conclusively, for patients with advanced Parkinson's disease sensitive to external stimulation at low minimum alveolar concentration, remifentanil co-administration is an option to avoid unstable hemodynamic conditions during subthalamic deep brain stimulation surgery.

Characterizing Canine Frontal Electroencephalographic Patterns and Cardiovascular Correlates at Different Anesthetic Levels of Sevoflurane

This study evaluated electroencephalogram [EEG] and cardiovascular correlation of sevoflurane anesthesia in healthy beagle dogs at varying minimum alveolar concentration (MAC) multiples. Processed EEG indices (Patient State Index [PSI], burst suppression ratio [SR], and Spectral Edge Frequency [SEF95], cardiovascular parameters (mean blood pressure [MBP], heart rate [HR]), and responses to noxious (electrical) stimuli were recorded. Deep anesthesia (2.5x MAC) resulted in the lowest PSI and MBP values (13.5 ± 9.9, 42.2 ± 7.4 mmHg, respectively), the highest SR (52.7 ± 35.4%), and dominant burst suppression. Surgical anesthesia (1.5x MAC) was characterized by alpha/low beta waves and the absence of response to noxious stimuli. At 1x MAC (2.1%), PSI and MBP increased (41.9 ± 12.6, 119.9 ± 17.7, respectively) while SR decreased (7.1 ± 13%). A moderate PSI-MBP correlation (ρ = 0.48, p = 0.002) was observed. Recovery was acceptable or smooth in most dogs. These findings suggest that sevoflurane disrupts cortical communication, inducing anesthesia and antinociception and that real-time EEG monitoring may aid in titrating sevoflurane delivery in conjunction with MBP.

The Probability Distribution of Times to Awakening From Sevoflurane Anesthesia, Among a Homogeneous Group of Cases With the Same Age-Adjusted Minimum Alveolar Concentration Fraction.

Human studies of awakening from general anesthesia inform understanding of neural mechanisms underlying recovery of consciousness. Probability distributions of times for emergence from anesthesia provide mechanistic information on whether putative biological models are generalizable. Previously reported distributions involved nonhomogenous groups, unsuitable for scientific comparisons. We used a retrospective cohort to identify surgeon-procedure combinations of homogeneous groups of patients and anesthetics to assess the probability distribution of extubation times to inform scientific studies of awakening from anesthesia. We hypothesized an acceptable fit to a log-normal distribution. Extubation times were recorded by anesthesia practitioners using an event button in the electronic health record. From 2011 through 2023, there were 182,374 cases with general anesthesia, not positioned prone, tracheal intubation after operating room entrance, interval from start to end of surgery ≥1 hour, and inhalational agent mean minimum alveolar concentration (MAC) fraction measured from case start through surgery end ≥0.6. We applied joint criteria of the same primary surgeon, surgical procedure, MAC fraction of each inhalational agent in 0.1 increments, and binary categories of adult, trainee finishing the anesthetic, bispectral index (BIS) monitor, N2O, sugammadex, and neostigmine. We considered all combinations of categories with ≥40 cases. We used Gas Man simulation to infer the probability distribution of volatile agent concentrations in the vessel-rich group (ie, brain). There were 48 cases among patients having oral surgery extractions by 1 surgeon, without anesthesia trainees, sevoflurane anesthesia with 0.3 MAC fraction at surgery end, without N2O, BIS monitor, or neuromuscular block reversal. Their extubation times followed a log-normal distribution (Shapiro-Wilk W = 0.98, P = .68). For the computer simulations, we assumed that patients differed solely in their binary threshold of vessel-rich group sevoflurane concentration at awakening (eg, patients with an awakening threshold of 0.26% would be unconscious for 0.1 to 14.8 minutes as sevoflurane is exhaled but the concentration remains ≥0.26%, and abruptly transition to consciousness at 15 minutes when the concentration reaches 0.25%). Expected awakening times would appear to be a log-normal distribution. A homogeneous patient population had a log-normal distribution of extubation times. Generalizable models of awakening should have that distribution. Clinicians change awakening times by their choice of agent and its MAC fraction at surgery end. Simulation suggests that the normal distribution in the log time scale for awakening, among patients with similar conditions, can represent a relatively uniform distribution among patients in the vessel-rich group (brain) partial pressure when the abrupt transition to consciousness occurs.

Impact of age on the reliability of GE Entropy™ module indices for guidance of maintenance of anaesthesia in adult patients: a single-centre retrospective analysis.

The GE Entropy™ module uses frontal EEG to compute the processed indices state entropy (SE), response entropy (RE), and burst suppression ratio (BSR) to guide maintenance of anaesthesia by supposedly minimising overly 'deep' or 'light' anaesthesia. It remains unclear whether the manufacturer-recommended index ranges accurately reflect anaesthesia levels or prevent complications such as burst suppression or arousal reactions. We retrospectively analysed 15 608 patient records, evaluating 14 770 adult patients (18-90 yr old) undergoing general anaesthesia. Age-dependent effects on processed index values were assessed using linear regression and Spearman's correlation coefficients (rho). During steady-state anaesthesia (BSR=0), only 38.4% (32.5-42.4%) of SE values were within the recommended range, with most values below the target. Age was positively associated with an increase in age-adjusted minimal alveolar concentration for volatile anaesthetics (adjusted [adj.] R2=0.18, P<0.001, rho=0.47 [0.20-0.70]). Despite this, SE paradoxically increased with age (adj. R2=0.45, P<0.001, rho=0.67 [0.51-0.79]). This trend persisted even during periods with positive BSR despite supposedly adequate SE values (adj. R2=0.73, P<0.001, rho=0.90 [0.80-0.95]). Maintaining anaesthesia within the recommended index range did not prevent positive BSR. Additionally, both frequency (adj. R2=0.70, P<0.001, rho=0.92 [0.85-0.95]) and duration (adj. R2=0.73, P<0.001, rho=0.89 [0.82-0.93]) of ΔRE-SE≥10, indicating arousal, increased with age. Despite their intuitive appeal, the processed EEG index values SE, RE, ΔRE-SE, and BSR showed limited reliability in guiding maintenance of anaesthesia, especially in older patients. Anaesthesiologists should not rely exclusively on the recommended index value range, as it is often unattainable and does not prevent burst suppression or arousal indicators.

Environmental and patient safety outcomes of a health-system Green Anesthesia Initiative (GAIA): a retrospective observational cohort study.

Environmental and patient safety outcomes of a health-system Green Anesthesia Initiative (GAIA): a retrospective observational cohort study.

Optimizing Anesthesia Management in Liver Transplantation With Use of Real Time Frontal Electroencephalogram.

Frontal electroencephalogram (fEEG) is a novel tool to monitor intraoperative sedation and may reduce anesthetic requirements. The utility of fEEG during liver transplantation has not been studied. The primary aim was to determine the association of fEEG with anesthetic requirement. Secondary aims included the effect of fEEG on intraoperative hemodynamics and postoperative outcomes. We performed a single-center retrospective cohort study of first-time, liver-alone transplant patients. Anesthetic requirement was measured by the mean minimum alveolar concentration of inhaled anesthetic. Hemodynamics were assessed by mean arterial pressure and total norepinephrine equivalents. Postoperative outcomes included time to extubation, mean postoperative sedation score, and incidence of delirium within five days of transplant. Both univariable and multivariable analysis was used. There were 37 fEEG-guided and 40 standard-of-care patients included in analysis. fEEG was associated with a 15% decrease of mean minimum alveolar concentration compared to standard-of-care (p <0.01). There was no association between fEEG and mean arterial pressure or total norepinephrine equivalents. fEEG-guided and standard-of-care patients had similar time-to-extubation (10 h vs. 10 h, p = 0.98) and incidence of post-operative delirium (19% vs. 10%, p = 0.43). fEEG was associated with a lower average postoperative sedation score (Beta = -0.2, p = 0.03). Our study demonstrated an association of fEEG with a reduced anesthetic requirement while maintaining adequate sedation. Patients monitored with fEEG had lower postoperative sedation scores, but no changes in other postoperative outcomes. Future prospective studies are needed to better elucidate the role of fEEG in liver transplantation, its impact on patient outcomes, and its implications for healthcare costs.

Increases in mean arterial blood pressure during electrical stimulation are unreliable indicators of anesthetic depth measured with electroencephalogram in dogs anesthetized with sevoflurane.

To evaluate the sparing effects of fentanyl and maropitant on sevoflurane minimum alveolar concentrations that block autonomic responses (MACBAR) and the hemodynamic and electroencephalographic responses to noxious stimuli in dogs. The sevoflurane MACBAR was determined in 5 healthy male Beagles with or without continuous infusions of fentanyl and maropitant. Then, intermittent noxious stimulation was applied at 1.3, 1.0, and 0.7 MACBAR. Heart rate (HR), mean arterial pressure (MAP), and Patient State Index (PSI) were measured for 6 minutes before and during 6 minutes of stimulation and analyzed with generalized linear mixed-effects models. Patient State Index occurrences above 50 during stimulation were noted. The effective dose for burst suppression was determined. The baseline MACBAR was 2.26% (1.34, 3.19). No MACBAR-sparing effect of fentanyl and maropitant was observed. At 1.3 MACBAR, MAP, HR, and PSI were 50 (41, 91) mm Hg, 90 (64, 112) beats/min, and 2 (0, 44). Mean arterial pressure and PSI increased, but not HR, with lower MACBAR multiples (P < .001). Noxious stimulation did not alter HR or PSI but elevated MAP. No PSI above 50 occurred at 1.3 MACBAR; however, 2 and 3 dogs showed brief PSI increases at 1.0 and 0.7 MACBAR. The effective dose for burst suppression was 3.15% (2.75, 3.75). Fentanyl and maropitant showed no MACBAR-sparing effect. At higher sevoflurane concentrations, noxious stimuli triggered an autonomic response; however, burst suppression was observed in the electroencephalogram. Variations in HR and MAP are unreliable indicators of anesthetic depth measured by electroencephalogram.

Comparison of Entropy Values of the Sevoflurane vs Isoflurane at Equal Minimum Alveolar Concentration in Patients Undergoing General Anesthesia during Wash-in and Wash-out Phases: A Prospective Randomized Study

Comparison of Entropy Values of the Sevoflurane vs Isoflurane at Equal Minimum Alveolar Concentration in Patients Undergoing General Anesthesia during Wash-in and Wash-out Phases: A Prospective Randomized Study

The Influence of Electroencephalographic Density Spectral Array Guidance of Sevoflurane Administration on Recovery From General Anesthesia in Children. A Randomized Controlled Trial.

In children, monitoring depth of anesthesia is challenging because of the still developing brain. Electroencephalographic density spectral array monitoring provides age- and anesthetic drug-specific electroencephalographic patterns, making it suitable for use in children. Yet, not much is known about the benefits of using density spectral array on post-operative recovery in children. In this randomized controlled trial, the primary aim was to investigate the influence of density spectral array monitoring during general anesthesia on the speed of recovery after surgery. Children aged 6 months-12 years scheduled for elective surgery under general anesthesia supplemented with caudal analgesia had either sevoflurane anesthesia titrated to maintain a characteristic density spectral array pattern or based on a predefined end-tidal sevoflurane concentration of 2.3% (standard care group). The time interval between the discontinuation of sevoflurane and the moment when discharge criteria from the operating room were met (Steward score of 3 or more) was defined as the primary outcome parameter of this trial. Data from 96 children were analyzed. The time until discharge readiness from the operating room was shorter in group density spectral array (6 min. [13[4-16.8]]) than in group standard care (12 min. [18[6-24.3]]), with a difference between medians of 6 min (95% CI -7 to 0), p = 0.041. The mean end-tidal sevoflurane concentration during the surgical procedure was lower in group density spectral array, 1.8% (0.34) versus 2.3% (0.1) in group standard care (95% CI 0.4-0.7), p < 0.001. This randomized controlled trial provides initial evidence of an added value of density spectral array monitoring in terms of the speed of recovery and allows sevoflurane to be dosed 22% lower during maintenance than with a more traditional approach using a minimal alveolar concentration of 0.9. ClinicalTrials.gov identifier: NCT05525104.

Optimization of inhaled anesthesia for Octodon degus using electroencephalography

Physiological responses to inhaled anesthetics vary among species. Therefore, a precise anesthetic technique is important for each individual species. In this study, we focused on the degu (Octodon degus), a small herbivorous rodent. Degus have recently begun to be used as laboratory models for brain research because of certain human-like characteristics, such as spontaneous development of Alzheimer's disease. In this study, we evaluated appropriate induction and maintenance anesthesia conditions for isoflurane and sevoflurane in degus by a stimulation test, electroencephalography (EEG), minimum alveolar concentration (MAC), and vital signs. During induction, more rapid time to loss of the righting reflex and deeper anesthesia in degus were observed in isoflurane. The MAC value for degus were 1.75 ± 0.0% in isoflurane and 2.25 ± 0.27% in sevoflurane. Whereas some degus were awake during maintenance anesthesia using both anesthetics at concentrations of ≤2%, no rats were awake when using sevoflurane at a concentration of 2%. The duration of the total flat EEG, a measure of the depth of maintenance anesthesia, was longer for isoflurane than for sevoflurane. Furthermore, higher concentrations of both anesthetics suppressed the respiratory rate in degus. These new findings regarding inhalation anesthesia in degus will contribute to future developments in the fields of laboratory animals and veterinary medicine.

Effects of mild cognitive impairment and sleep disorders on the minimum alveolar concentration value of sevoflurane

ObjectivesTo explore the effect of mild cognitive impairment (MCI) and MCI with sleep disorders on the potency of sevoflurane anesthesia in the elderly.DesignProspective study methods. Dixon up-and-down methods.SettingComprehensive public tertiary hospital, Cangzhou City, Hebei Province, China.Participants70 elderly patients scheduled for elective unilateral breast cancer surgery and finally analyzed 58 patients, including 30 patients with MCI (group M) and 28 patients with MCI with sleep disorders (group MS).Outcome measuresThe required minimum alveolar concentration (MAC) value of sevoflurane in the two groups was determined using the Dixon up-and-down method. The MAC value of sevoflurane and its 95% confidence interval (CI) were calculated using the logistic regression method. Serum melanin-concentrating hormone concentrations were determined by Elisa kits.ResultsThe MAC value of sevoflurane in group M was 1.43 (95% CI 1.05–1.61%), and the MAC value of sevoflurane in group MS was 1.93 (95% CI 1.78–2.08%), There were notable differences between the two groups (P < 0.0001). The level of melanin-concentrating hormone (MCH) in the MS group was significantly lower than that in the M group (21.52 ± 3.82 vs. 37.17 ± 3.66 pg/ml, P < 0.0001). There was a significant negative correlation between MCH levels and the probability of body movement during skin incision (OR = 0.844, 95% CI: 0.715–0.996, P = 0.045).ConclusionsPatients with MCI with sleep disorders required higher doses of sevoflurane than those with MCI alone. Changes in anesthetic requirements may be related to changes in MCH levels.

Electroencephalography and Anesthetic Depth in Children Under 2 Years of Age: A Prospective Observational Study.

Processed electroencephalogram (EEG) indices are widely used to monitor anesthetic depth. However, their reliability in children under 2 years of age remains questionable. During anesthesia maintenance in this age group, processed EEG indices frequently exhibit unexpectedly elevated values that exceed the intended target range. This study aimed to identify EEG spectral parameters associated with false positive elevations in processed EEG indices and investigate their differences from true positive elevations during emergence. This prospective observational study included 50 children aged 4-24 months undergoing general anesthesia. Bispectral index (BIS), patient state index (PSi), and raw EEG were continuously recorded throughout anesthesia. False positive was defined as elevated processed EEG indices when end-tidal sevoflurane concentration was maintained at 0.7-1.3 minimum alveolar concentration, with heart rate and mean blood pressure between 80% and 120% of baseline values. We analyzed EEG power spectra and band power values during periods of false positives and compared them with those of true positives during emergence. Bonferroni-corrected p < 0.05 was considered significant. False positives in processed EEG indices were observed in 35 (70%) of the children during anesthesia maintenance, occupying 28% of the maintenance phase. These false positives were associated with decreased power in delta (269-174 dB) and theta (115-97 dB) bands, but widespread increases in alpha and beta bands, resulting in elevated spectral edge frequency (19-22 Hz). Notably, EEG band power during false positives significantly differed from those observed during emergence (delta: 52 dB, theta: 38 dB) (all p < 0.001). Processed EEG indices may exhibit unexpectedly elevated values during anesthesia maintenance in children under 2 years of age. Quantitative assessments derived from raw EEG data may improve the evaluation of anesthetic depth in this population.

The Value of Auditing the Frequency of Inhalational Anesthetics With a Combination of Very Low Bispectral Index and High Fraction of the Age-Adjusted Minimum Alveolar Concentration

The Value of Auditing the Frequency of Inhalational Anesthetics With a Combination of Very Low Bispectral Index and High Fraction of the Age-Adjusted Minimum Alveolar Concentration

Effects of Progesterone on Isoflurane Requirement for Balance Disturbance and Loss of Righting Reflex in Male Mice.

Introduction It has been known that progesterone has central effects, as measured by minimum alveolar concentration in various experimental settings. Previously, we showed that progesterone reduces the sevoflurane requirement for the loss of righting reflex (LORR) using male mice. However, the combination of progesterone and isoflurane has not been studied. Therefore, in this study, we compared the effect of progesterone on anesthetic requirements in a mouse model. Methods Male C57BL/6 mice were treated with either progesterone (75 mg/kg) + olive oil or only olive oil. Animals were studied in closed cylinders supplied with oxygen and isoflurane that rotated four times per minute. Balance disturbance and loss of the righting reflex were counted. The data were analyzed by using a multiple independent variable logistics regression model. Results The concentrations at the onset of balance disturbances, represented by the effective dose 50% (ED50) and effective dose 95% (ED95) of isoflurane, were 0.37% and 0.45% for the control group and 0.34% and 0.41% for the progesterone group, respectively. Similarly, the concentrations for loss of righting reflex (LORR), represented by ED50 and ED95, were 0.55% and 0.62% for the control group and 0.53% and 0.60% for the progesterone group, respectively. Subcutaneous injection of progesterone at a dose of 75 mg/kg significantly reduced the isoflurane requirement for both balance disturbance (p = 0.0022) and LORR (p = 0.0218). Conclusion We conclude that progesterone decreased isoflurane concentration for both balance disturbance and LORR.

Anesthetic dose‐adjusted intraoperative alpha power in association with biomarkers of preclinical Alzheimer’s disease, preoperative attention function, and postoperative delirium

AbstractBackgroundPostoperative delirium (POD) is characterized by fluctuating attention after surgery and is associated with increased risk of developing Alzheimer’s Disease (AD). While the neurophysiological changes that underlie POD and increased risk of AD are unclear, recent data has raised the possibility that an exaggerated brain response to anesthetics may be a biomarker for POD risk and preclinical AD‐like pathology. Thus, we examined whether anesthetic‐dose‐adjusted intraoperative brain activity is associated with POD or preoperative brain vulnerabilities (preclinical AD‐like pathology, preoperative inattention) that may contribute to risk of POD (and later AD).Method82 patients from 3 prospective cohort studies of non‐cardiac, non‐neurologic surgical patients age ≥60 who had sufficient 32‐channel intraoperative electroencephalographic (EEG) data and received a gas anesthetic for ≥80% of their surgery were included. Other data included preoperative cerebrospinal fluid (CSF) samples, preoperative cognitive testing, and delirium scores (before surgery and twice daily for ≤5 days after surgery). Univariable associations were evaluated between 8‐12Hz anesthetic‐dose‐adjusted frontoparietal EEG alpha power and 1) preoperative CSF AD biomarkers (pTau181p, Aβ42, pTau181p/Aβ42), 2) preoperative attention function, and 3) POD incidence and severity. To account for the brain’s response to anesthetics, alpha power was dose‐adjusted as follows: (alpha power at each minute of surgery) / (2.5 – age‐adjusted minimum alveolar concentration at each minute of surgery) and summarized by patient across minutes as the mean of median‐filtered alpha.ResultLower dose‐adjusted intraoperative frontoparietal alpha power was found among patients 1) with (vs. without) preoperative pTau/Aβ pathology (Table 1), and 2) among those who scored worse on timed preoperative attention tasks (Table 2). Low dose‐adjusted alpha power was also associated with increased odds of POD and moderate‐to‐severe delirium symptomology (Table 3). The conclusions were similar for unadjusted alpha power, though only dose‐adjusted values were associated with POD severity. Overall, the results suggest that, regardless of our anesthetic‐dose‐adjustment, low intraoperative frontoparietal alpha power is associated with CSF pTau/Aβ pathology, attention function, and POD.ConclusionFuture studies are needed to determine whether there are causal pathways between preoperative brain vulnerabilities, intraoperative frontoparietal alpha power, and POD. Understanding these pathways will improve our ability to identify at‐risk patients for targeted interventions.

Impact of low-dose sevoflurane with propofol-based anesthesia on motor-evoked potentials in infants: a single-arm crossover pilot study

PurposeThe influence of anesthetic interactions on motor-evoked potentials in infants has rarely been reported. In infants, adding a small dose of sevoflurane to propofol-based total intravenous anesthesia is reasonable for reducing propofol administration. We collected preliminary data regarding the effect of low-dose sevoflurane in propofol-based total intravenous anesthesia on motor-evoked potentials in infants.MethodsThis pilot interventional study included 10 consecutive infants requiring motor-evoked potentials between January 2023 and March 2024. The motor-evoked potential amplitudes in the upper and lower extremities were recorded twice when general anesthesia was maintained using (1) propofol-based total intravenous anesthesia and (2) 0.1–0.15 age-adjusted minimum alveolar concentration sevoflurane + propofol-based total intravenous anesthesia.ResultsThe motor-evoked potential amplitude in the right upper extremity was not significantly different after the addition of a small dose of sevoflurane [192 (75.3–398) μV, 121 (57.7–304) μV, P = 0.19]. All the motor-evoked potential amplitudes in the right lower extremity (quadriceps femoris, anterior tibialis, and gastrocnemius muscles) were significantly attenuated by adding a small dose of sevoflurane (median [interquartile range]: 47.9 [35.4–200] μV, 25.2 [12.4–55.3] μV, P = 0.014; 74.2 [51.9–232] μV, 31.2 [2.7–64] μV, P = 0.0039; 29.8 [20–194] μV, 9.9 [3.8–92.4] μV, P = 0.0039, respectively). Similar results were observed in the left lower extremities.ConclusionAdding even 0.1–0.15 age-adjusted minimum alveolar concentration sevoflurane to propofol-based total intravenous anesthesia attenuated the motor-evoked potential amplitudes in the lower extremities. A further prospective interventional study with an appropriate sample size is required to investigate the study hypothesis.

Erector spinae plane block (ESPB) enhances hemodynamic stability decreasing analgesic requirements in surgical stabilization of rib fractures (SSRFs)

ObjectiveTo evaluate the efficacy of erector spinae plane block (ESPB) on intraoperative hemodynamic stability, opioid and inhalation anesthetic requirements and postoperative analgesic effects in patients undergoing surgical stabilization of rib fractures (SSRFs).MethodsWe retrospectively reviewed 173 patients who underwent surgical stabilization of rib fractures between May 2020 and December 2023. The patients were allocated into the ESPB group or the control group. Demographic data, intraoperative hemodynamic parameters, total intraoperative opioid consumption, the average minimum alveolar concentration (MAC) of inhalational anesthetics, postoperative simple analgesics and opioid consumption and the length of hospital stay were included in the analysis.ResultsCompared with the control group, the ESPB group had a lower heart rate (HR) in the first 90 min after surgical incision and lower systolic blood pressure (SBP) and mean arterial pressure (MAP) at the beginning of surgery. Intraoperatively, a notable reduction in fentanyl consumption was observed in the ESPB group (p = 0.004), whereas no significant difference was observed in the average MAC of inhalational agents (p = 0.073). Postoperatively, the ESPB group required fewer doses of simple analgesics in the first 24 h (p < 0.001) and 48 h (p = 0.029). No statistically significant difference in the length of hospital stay (p = 0.608) was observed between the groups.ConclusionESPB was shown to enhance intraoperative hemodynamic stability, reduce opioid consumption and decrease postoperative analgesic consumption in patients who underwent SSRF. These results suggest that ESPB may serve as a valuable component of multimodal analgesia protocols for SSRF. Larger prospective studies are warranted to confirm the results and evaluate long-term outcomes.

Effect of buprenorphine delivered by target-controlled infusion on the minimum alveolar concentration of isoflurane in cats

Effect of buprenorphine delivered by target-controlled infusion on the minimum alveolar concentration of isoflurane in cats

Risk of postoperative delirium in older adults under balanced general anesthesia

Anesthetic depth can influence the incidence of postoperative delirium (POD). This depth is related to the potency of the volatile anesthetics used to maintain balanced general anesthesia. This potency is measured by means of the minimum alveolar concentration (MAC). In older adults, it is unknown which MAC is associated with the risk of POD. To estimate the risk of POD associated with minimum alveolar concentration (MAC) levels of volatile anesthetics in older adults who received balanced general anesthesia. A prospective cohort study was carried out with 119 patients, aged ≥ 60 years, with 0 points in the 4 "As" test (4AT), without neurological or psychiatric diseases. During the intraoperative period, the CAM provided was recorded, and in the postoperative period, the presence of emergency with delirium and/or POD was evaluated at 2 and 24 hours, considering a score ≥ 4. A longer hospital stay was found in the group that received a MAC ≥0.9. The incidence of POD was 29.4%. Those who received a MAC ≥ 0.9 had an RR of 2.22 (95%CI: 1.2-4.2) of presenting POD. An adjusted logistic regression model was performed with the variables female sex (OR: 4, 95%CI: 1.5-10.4), ASA physical status 3-4 (OR: 3.7, 95%CI: 1.5-9) and MAC ≥ 0.9 (OR: 3.1 95%CI: 1.2-8) with an R2: 0.26 and a constant of 3.005. MAC ≥ 0.9 represents a risk factor for DPO, so individualized dosing of volatile anesthetics should be used.

Antinociceptive and anesthetic-sparing effects of levomethadone/fenpipramide cannot be enhanced by coadministration of metamizole in awake and anesthetized Beagles.

To determine the effect of levomethadone/fenpipramide and metamizole alone and in combination on acute nociception. 8 healthy, adult Beagles were used in 2 separate randomized, complete crossover, experimental trials (threshold testing and determination of minimal alveolar concentration [MAC]) with masked observers. In both trials, treatments were 0.2 mg·kg-1 levomethadone/fenpipramide (L), 75 mg·kg-1 metamizole (M), or their combination (LM). In conscious dogs, mechanical thresholds were determined using constantly rising force. Thermal thresholds were measured via ramped contact heat. The MAC of sevoflurane was determined using the bracketing method with electrical stimulus (50 V, 50 Hz, 10 ms) before and 1 and 4 hours after treatment. Mechanical thresholds in L and LM were significantly increased above baseline (BL) for 165 minutes and above M for 135 minutes. Percent thermal threshold excursion significantly increased above BL in L for 75 minutes and in LM for 135 minutes. In L and LM, the percent thermal threshold excursion was significantly higher than in M from 15 to 75 or 135 minutes, respectively. In L and LM, the MAC of sevoflurane was significantly reduced at 1 hour compared to BL and M. Duration but not the magnitude of thermal antinociception of levomethadone/fenpipramide was increased by metamizole. Mechanical antinociception in awake dogs and anesthetic-sparing effects of levomethadone/fenpipramide were not altered. Coadministration of levomethadone/fenpipramide and metamizole to increase antinociception is not justified.