Comparison of the negative effect of remimazolam and propofol on cardiac contractility: Analysis of a randomised parallel-group trial and a preclinical ex vivo study.

Remimazolam is a newly developed ultra-short-acting benzodiazepine that exerts sedative effects. This study aimed to clarify the effects of remimazolam on cardiac contractility. In a randomised-parallel group trial, haemodynamic parameters were compared between propofol (n = 11) and remimazolam (n = 12) groups during the induction of general anaesthesia in patients undergoing non-cardiac surgery. In a preclinical study, the direct effects of remimazolam on cardiac contractility were also evaluated using isolated rat hearts. RNA sequence data obtained from rat and human hearts were analysed to assess the expression patterns of the cardiac γ-aminobutyric acid type A (GABAA ) receptor subunits. In a clinical study, the proportional change of the maximum rate of arterial pressure rise was milder during the study period in the remimazolam group (propofol: -52.6 [10.2] (mean [standard deviation])% vs. remimazolam: -39.7% [10.5%], p = 0.007). In a preclinical study, remimazolam did not exert a negative effect on left ventricle developed pressure, whereas propofol did exert a negative effect after bolus administration of a high dose (propofol: -26.9% [3.5%] vs. remimazolam: -1.1 [6.9%], p < 0.001). Analysis of the RNA sequence revealed a lack of γ subunits, which are part of the major benzodiazepine binding site of the GABAA receptor, in rat and human hearts. These results indicate that remimazolam does not have a direct negative effect on cardiac contractility, which might contribute to its milder effect on cardiac contractility during the induction of general anaesthesia. The expression patterns of cardiac GABAA receptor subunits might be associated with the unique pharmacokinetics of benzodiazepines in the heart.

Comparing leak pressure of LMA® ProSeal™ versus i-gel® at head rotation: a randomized controlled trial.

PURPOSE: The effect of head rotation on supraglottic airway (SGA) oropharyngeal leak pressure (OPLP) has not been well elucidated. The aim of this study was to help clarify which SGA device provides higher OPLP at head-rotated position. METHODS: Patients who underwent elective surgery under general anesthesia were enrolled and randomly divided into laryngeal mask airway (LMA®) ProSeal™ and i-gel® groups. The allocated SGA device was inserted under anesthesia. The primary outcome was OPLP, and secondary outcomes were ventilation score, expiratory tidal volume, and maximum pressure under volume-controlled ventilation (VCV) with an inspiratory tidal volume of 10 mL·kg-1 ideal body weight and fibreoptic view of the vocal cords at 0°, 30°, and 60° head rotation. RESULTS: Data from 78 and 76 patients were analyzed in the LMA ProSeal and i-gel groups, respectively. The mean (standard deviation) OPLP of the LMA ProSeal was significantly higher than that of the i-gel at the 60° head-rotated position (LMA ProSeal, 20.4 [6.5] vs i-gel, 16.9 [7.8] cm H2O; difference in means, 3.6; adjusted 95% confidence interval, 0.5 to 6.6; adjusted P = 0.02, adjusted for six comparisons). The maximum pressure under VCV at 60° head rotation was significantly higher in the LMA ProSeal group than in the i-gel group. The expiratory tidal volume of the LMA ProSeal did not significantly change with head rotation and was significantly higher than that of the i-gel at 60° head rotation. Ventilation score, fibreoptic view of the vocal cords, and complications were not significantly different between the ProSeal and i-gel groups. CONCLUSIONS: The LMA ProSeal provides higher OPLP than the i-gel at a 60° head-rotated position under general anesthesia. TRIAL REGISTRATION: Japan Registry of Clinical Trials (https://jrct.niph.go.jp) (JRCT1012210043); registered 18 October 2021.

RéSUMé: OBJECTIF: L'effet de la rotation de la tête sur la pression de fuite oropharyngée (OPLP en anglais) des dispositifs supraglottiques (DSG) n'est pas encore bien élucidé. L'objectif de cette étude était d'aider à déterminer quel DSG procurait une pression de fuite oropharyngée plus élevée lorsque la tête est en rotation. MéTHODE: Les patient·es qui ont bénéficié d'une intervention chirurgicale non urgente sous anesthésie générale ont été recruté·es et aléatoirement réparti·es en deux groupes, soit masque laryngé (LMA®) ProSeal™ ou i-gel®. Le DSG alloué a été inséré sous anesthésie. Le critère d'évaluation principal était la pression de fuite oropharyngée, et les critères d'évaluation secondaires étaient le score de ventilation, le volume courant expiratoire et la pression maximale sous ventilation à volume contrôlé (VVC) avec un volume courant inspiratoire de 10 mL·kg−1 du poids corporel idéal et une visualisation fibroscopique des cordes vocales à une rotation de la tête de 0°, 30° et 60°. RéSULTATS: Les données de 78 et 76 patient·es ont été analysées dans les groupes LMA ProSeal et i-gel, respectivement. La pression de fuite oropharyngée moyenne (écart type) du LMA ProSeal était significativement plus élevée que celle de l'i-gel en position de rotation de la tête à 60° (LMA ProSeal, 20,4 [6,5] vs i-gel, 16,9 [7,8] cm H2O; différence de moyennes, 3,6; intervalle de confiance ajusté à 95 %, de 0,5 à 6,6; P = 0,02 ajusté, ajusté pour six comparaisons). La pression maximale sous VVC à une rotation de la tête de 60° était significativement plus élevée dans le groupe LMA ProSeal que dans le groupe i-gel. Le volume courant expiratoire du LMA ProSeal n'a pas changé de manière significative avec la rotation de la tête et était significativement plus élevé que celui de l'i-gel à une rotation de la tête de 60°. Le score de ventilation, la visualisation fibroscopique des cordes vocales et les complications n'étaient pas significativement différents entre les groupes ProSeal et i-gel. CONCLUSION: Le LMA ProSeal procure une pression de fuite oropharyngée plus élevée que l'i-gel dans une position de rotation de la tête à 60° sous anesthésie générale. ENREGISTREMENT DE L'éTUDE: Registre japonais des essais cliniques (https://jrct.niph.go.jp) (JRCT1012210043); enregistré le 18 octobre 2021.

INJEX50 could improve the success rate of local anesthesia for arterial cannulation in the pediatric intensive care unit: A randomized, double-blind, single-center study.

BACKGROUND: Quick arterial cannulation is required in pediatric emergency situation, which require effective local anesthesia to avoid withdrawal movement. However, pediatric local anesthesia could be difficult because of withdrawal movement. Jet injectors, which are needleless and provide local anesthesia quickly, could be helpful for pediatric local anesthesia during arterial cannulation. AIMS: This study aimed to examine whether new jet injector "INJEX50" could improve the success rate of local anesthesia for arterial cannulation in pediatric intensive care unit compared with the current standard of care, infiltration using a 26-gauge needle. METHODS: This study was a randomized, double-blind, single-center study. Participants were infants and young children in the pediatric intensive care unit, who required an arterial line. Local anesthesia was performed with either a 26-gauge needle (group C) or INJEX50 (group I) before arterial cannulation. The primary outcome (success of local anesthesia) was the presence of withdrawal movement at the time of skin puncture for arterial cannulation. The secondary outcomes included rescue sedation during arterial cannulation. Data were analyzed using Fisher's exact test and the Mann-Whitney U-test, with values of p < .05 considered statistically significant. RESULTS: Seventy patients were randomly assigned to groups C and I. The local anesthesia success rate in group I (30/35 [86%]) was significantly higher than that in group C (15/35 [43%], odds ratio, 8.00; 95% confidence interval, 2.51-25.5; p = .0005). In conclusion, INJEX50 could improve success rate of local anesthesia for arterial cannulation in pediatric intensive care unit compared with 26-gauge needle.

The 10 Hz dynamic response of a fluid-filled pressure monitoring system is a novel alternative to the fast flush test and indicative of unacceptable systolic pressure overshoot.

The standard method for qualitatively evaluating the dynamic response is to see if the gain of the amplitude spectrum curve approaches 1 (input signal = output signal) over the frequency band of the blood pressure waveform. In a previous report, Watanabe reported that Gardner's natural frequency and damping coefficient, which are widely used as evaluation methods, do not reflect the dynamic response of the circuit. Therefore, new parameters for evaluating the dynamic response of pressure monitoring circuits were desired. In this study, arterial pressure catheters with length of 30, 60, 150, and 210 cm were prepared, and a blood pressure wave calibrator, two pressure monitors with analog output and a personal computer were used to analyze blood pressure monitoring circuits. All data collection and analytical processes were performed using step response analysis program. The gain at 10 Hz was close to 1 and the systolic blood pressure difference was small in the short circuits (30 cm, 60 cm), and the gain at 10 Hz was 1.3-1.5 in the 150 cm circuit and over 1.7 in the 210 cm circuit. The difference in systolic blood pressure increased in proportion to the length of the circuit. It could also be inferred that the gain at 10 Hz should be less than 1.2 to meet a clinically acceptable blood pressure difference. In conclusion, the gain at 10 Hz is sufficiently useful as an indicator to determine the correct systolic blood pressure.

Radial artery catheterization using a novel T-type ultrasound probe: a single-center randomized study.

Ultrasound guidance has been reported to facilitate radial artery catheterization compared with the palpation method. However, a recent meta-analysis showed that there was not significant differences in the first attempt success rate between the long-axis in-plane (LA-IP) method and the short-axis out-of-plane method. In 2023, we started using a novel T-type probe. We can recognize the needle first during the radial artery access with the short-axis view and then dose it with the long-axis view using the T-type probe. Therefore, we hypothesized that the T-type probe-guided method might heighten the first attempt success rate in radial artery catheterization, even for non-expert practitioners, compared with the LA-IP technique. One hundred and fifty adult patients, older than 20 years, ASA I to III, were randomly assigned to the T-type probe-guided group (Group T: n = 75) or the LA-IP group (Group L: n = 75). The primary outcome was the first attempt success rate. The first attempt success rate in Group T (49/71, 69%) was significantly higher than that in Group L (31/68, 46%) (p = 0.0062). The present study showed that the T-type probe might facilitate the radial artery catheterization rather than the LA-IP method.

Differences in circulating blood volume changes during emergence from general anesthesia in transcatheter aortic valve implantation and MitraClip implantation.

PURPOSE: We aimed to compare changes in the circulating blood volume (CBV) during emergence from general anesthesia in patients undergoing transcatheter aortic valve implantation (TAVI) and MitraClip implantation. METHOD: We included 97 patients who underwent TAVI or MitraClip implantation. The primary outcome was the rate of change in the estimated CBV associated with emergence from general anesthesia. The secondary outcomes were hemoglobin and hematocrit values before and after emergence from anesthesia for each procedure. Additionally, the independent factors associated with changes in the estimated CBV were assessed using multiple regression analysis. RESULTS: In the TAVI group, the hemoglobin concentration increased from 9.6 g/dL before emergence from anesthesia to 10.8 g/dL after emergence (P < 0.001; mean difference, 1.2 g/dL, 95% confidence interval [CI] 1.1-1.3 g/dL). Conversely, no statistically significant change was observed in the hemoglobin concentration before and after emergence from anesthesia in the MitraClip group. The mean rate of change in the estimated CBV was - 15.4% (standard deviation [SD] 6.4%) in the TAVI group and - 2.4% (SD, 4.7%) in the MitraClip group, indicating a significant decrease in the estimated CBV in the former than in the latter (P < 0.001; mean difference, 13.0%; 95% CI 9.9-16.1%). CONCLUSION: Emergence from general anesthesia increased the hemoglobin concentration and decreased the estimated CBV in patients undergoing TAVI but did not elicit significant changes in patients undergoing MitraClip implantation. These results may provide a rationale for minimizing blood transfusions during general anesthesia in patients undergoing these procedures.

Albumin protects the ultrastructure of the endothelial glycocalyx of coronary arteries in myocardial ischemia-reperfusion injury in vivo.

Myocardial ischemia-reperfusion (I/R) injury induces endothelial glycocalyx (GCX) degradation. Several candidate GCX-protective factors including albumin have been identified, few have been demonstrated in in vivo studies and most albumins used to date have been heterologous. Albumin is a carrier protein for sphingosine 1-phosphate (S1P), which has protective effects on the cardiovascular system. However, changes inhibited by albumin in the endothelial GCX structure in I/R in vivo via the S1P receptor has not been reported. In this study, we aimed to determine whether albumin prevents the shedding of endothelial GCX in response to I/R in vivo. Rats were divided into four groups: control (CON), I/R, I/R with albumin preload (I/R + ALB), and I/R + ALB with S1P receptor agonist fingolimod (I/R + ALB + FIN). FIN acts as an initial agonist of S1P receptor 1 and downregulates the receptor in an inhibitory manner. The CON and I/R groups received saline and I/R + ALB and I/R + ALB + FIN groups received albumin solution before left anterior descending coronary artery ligation. Our study used rat albumin. Shedding of endothelial GCX was evaluated in the myocardium by electron microscopy, and the concentration of serum syndecan-1 was measured. Thus, albumin administration maintained the structure of endothelial GCX and prevented shedding of endothelial GCX via the S1P receptor in myocardial I/R, and FIN annihilated the protective effect of albumin against I/R injury.

Dexmedetomidine as a cardioprotective drug: a narrative review.

Dexmedetomidine (DEX), a highly selective alpha2-adrenoceptors agonist, is not only a sedative drug used during mechanical ventilation in the intensive care unit but also a cardio-protective drug against ischemia-reperfusion injury (IRI). Numerous preclinical in vivo and ex vivo studies, mostly evaluating the effect of DEX pretreatment in healthy rodents, have shown the efficacy of DEX in protecting the hearts from IRI. However, whether DEX can maintain its cardio-protective effect in hearts with comorbidities such as diabetes has not been fully elucidated. Multiple clinical trials have reported promising results, showing that pretreatment with DEX can attenuate cardiac damage in patients undergoing cardiac surgery. However, evidence of the post-treatment effects of DEX in clinical practice remains limited. In this narrative review, we summarize the previously reported evidence of DEX-induced cardio-protection against IRI and clarify the condition of the hearts and the timing of DEX administration that has not been tested. With further investigations evaluating these knowledge gaps, the use of DEX as a cardio-protective drug could be further facilitated in the management of patients undergoing cardiac surgery and might be considered in a broader area of clinical settings beyond cardiac surgery, including patients with acute myocardial infarction.

Effect of remimazolam on intraoperative neurophysiology monitoring of visual-evoked potential: a case series.

There are very few reports on the effects of benzodiazepines such as midazolam and diazepam on intraoperative visual-evoked potential (VEP), and there is no report on the effect of remimazolam at all. Five patients underwent neurosurgery using VEP monitoring for avoiding surgical injury to the optic nerve. In all cases, drug administration was based on actual body weight. General anesthesia was induced with propofol and remifentanil, and then maintained with propofol at target concentrations of 2.7-3.5 µg/ml for maintaining bispectral index (BIS) between 40 and 60. After resection of the tumor under stable VEP, we discontinued propofol immediately followed by infusion of remimazolam at 12 mg/kg/h for a few seconds, then reduced to 1 mg/kg/h. After a time, when blood levels of remimazolam appeared to be stable, VEP was monitored again and compared to controls. In all cases, we were able to confirm that there was reproducibility. Remimazolam may provide a comparable quality of anesthesia to that of existing drugs for VEP in neurosurgery.

The intraoperative motor-evoked potential when propofol was changed to remimazolam during general anesthesia: a case series.

Remimazolam is a short-acting benzodiazepine that was approved for clinical use in 2020. We report three patients who underwent surgery for cerebral and spinal cord tumors, in whom transcranial electrical stimulation-motor-evoked potential (TES-MEP) was successfully monitored under general anesthesia with remimazolam. During total intravenous anesthesia with propofol at a target concentration of 2.7 - 3.5 µg/mL and 0.1 - 0.35 µg/kg/min of remifentanil, delayed awakening, bradycardia, and hypotension during propofol anesthesia were expected in all three cases. With patient safety as the top priority, we considered changing the anesthetic agent. Propofol was replaced with remimazolam at a loading dose of 12 mg/kg/h for a few seconds (case 3), followed by 1 mg/kg/h for maintenance (cases 1-3). TES-MEP was recorded during propofol and remimazolam administration in all three patients. Amplitudes of TES-MEP during anesthesia with propofol and remimazolam were 461.5 ± 150 µV and 590.5 ± 100.9 µV, 1542 ± 127 µV and 1698 ± 211 µV, and 581.5 ± 91.3 µV and 634 ± 82.7 µV sequentially from Case 1. Our findings suggest that intraoperative TES-MEP could be measured when anesthesia was managed with remimazolam at 1 mg/kg/h.

Head cooling wrap could suppress the elevation of core temperature after cardiac surgery during forced-air warming in a pediatric intensive care unit: a randomized clinical trial.

PURPOSE: The main aim of the current trial was to explore our hypothesis that cooling head wraps lower the core temperature more effectively than ice packs on the head during forced-air warming after pediatric cardiac surgeries. METHODS: This study was a single-center Randomized Controlled Trial. Participants were children with a weight ≤ 10 kg and hyperthermia during forced-air warming after cardiac surgeries. When the core temperature reached 37.5 °C, ice packs on the head (group C) or a cooling head wrap (group H) were used as cooling devices to decrease the core temperature. The primary outcome was the core temperature. The secondary outcomes were the foot surface temperature and heart rate. We measured all outcomes every 30 min for 240 min after the patient developed hyperthermia. We conducted two-way ANOVA as a pre-planned analysis and also the Bonferroni test as a post hoc analysis. RESULTS: Twenty patients were randomly assigned to groups C and H. The series of core temperatures in group H were significantly lower than those in group C (p < 0.0001), and post hoc analysis showed that there was no significant difference in core temperatures at T0 between the two groups and statistically significant differences in all core temperatures at T30-240 between the two groups. There was no difference between the two groups' surface temperatures and heart rates. CONCLUSIONS: Compared to ice packs on the head, head cooling wraps more effectively suppress core temperature elevation during forced-air warming after pediatric cardiac surgery.

Effect of cerebrospinal fluid drainage pressure in descending and thoracoabdominal aortic repair: a prospective multicenter observational study.

PURPOSE: Cerebrospinal fluid drainage (CSFD) is recommended during open or endovascular thoracic aortic repair. However, the incidence of CSFD complications is still high. Recently, CSF pressure has been kept high to avoid complications, but the efficacy of CSFD at higher pressures has not been confirmed. We hypothesize that CSFD at higher pressures is effective for preventing motor deficits. METHODS: This prospective observational study included 14 hospitals that are members of the Japanese Society of Cardiovascular Anesthesiologists. Patients who underwent thoracic and thoracoabdominal aortic repair were divided into four groups: Group 1, CSF pressure around 10 mmHg; Group 2, CSF pressure around 15 mmHg; Group 3, CSFD initiated when motor evoked potential amplitudes decreased; and Group 4, no CSFD. We assessed the association between the CSFD group and motor deficits using mixed-effects logistic regression with a random intercept for the institution. RESULTS: Of 1072 patients in the study, 84 patients (open surgery, 51; thoracic endovascular aortic repair, 33) had motor deficits at discharge. Groups 1 and 2 were not associated with motor deficits (Group 1, odds ratio (OR): 1.53, 95% confidence interval (95% CI): 0.71-3.29, p = 0.276; Group 2, OR: 1.73, 95% CI: 0.62-4.82) when compared with Group 4. Group 3 was significantly more prone to motor deficits than Group 4 (OR: 2.56, 95% CI: 1.27-5.17, p = 0.009). CONCLUSION: CSFD is not associated with motor deficits in thoracic and thoracoabdominal aortic repair with CSF pressure around 10 or 15 mmHg.

Dexmedetomidine Ameliorates Perioperative Neurocognitive Disorders by Suppressing Monocyte-Derived Macrophages in Mice With Preexisting Traumatic Brain Injury.

BACKGROUND: Traumatic brain injury (TBI) initiates immune responses involving infiltration of monocyte-derived macrophages (MDMs) in the injured brain tissue. These MDMs play a key role in perioperative neurocognitive disorders (PNDs). We tested the hypothesis that preanesthetic treatment with dexmedetomidine (DEX) could suppress infiltration of MDMs into the hippocampus of TBI model mice, ameliorating PND. METHODS: We first performed bone marrow transplantation from green fluorescent protein-transgenic mice to C57BL/6 mice to identify MDMs. We used only male mice for homogeneity. Four weeks after transplantation, a controlled cortical impact model of TBI was created using recipient mice. Four weeks after TBI, mice received pretreatment with DEX before general anesthesia (GA). Mice performed the Barnes maze test (8-12 mice/group) 2 weeks after GA and were euthanized for immunohistochemistry (4-5 mice/group) or immunoblotting (7 mice/group) 4 weeks after GA. RESULTS: In Barnes maze tests, TBI model mice showed longer primary latency (mean difference, 76.5 [95% confidence interval, 41.4-111.6], P < .0001 versus Naïve), primary path length (431.2 [98.5-763.9], P = .001 versus Naïve), and more primary errors (5.7 [0.62-10.7], P = .017 versus Naïve) than Naïve mice on experimental day 3. Expression of MDMs in the hippocampus was significantly increased in TBI mice compared to Naïve mice (2.1 [0.6-3.7], P = .003 versus Naïve). Expression of monocyte chemotactic protein-1 (MCP1)-positive areas in the hippocampus was significantly increased in TBI mice compared to Naïve mice (0.38 [0.09-0.68], P = .007 versus Naïve). Immunoblotting indicated significantly increased expression of interleukin-1ß in the hippocampus in TBI mice compared to Naïve mice (1.59 [0.08-3.1], P = .035 versus Naïve). In contrast, TBI mice pretreated with DEX were rescued from these changes and showed no significant difference from Naïve mice. Yohimbine, an α2 receptor antagonist, mitigated the effects of DEX (primary latency: 68.3 [36.5-100.1], P < .0001 versus TBI-DEX; primary path length: 414.9 [120.0-709.9], P = .0002 versus DEX; primary errors: 6.6 [2.1-11.2], P = .0005 versus TBI-DEX; expression of MDMs: 2.9 [1.4-4.4], P = .0001 versus TBI-DEX; expression of MCP1: 0.4 [0.05-0.67], P = .017 versus TBI-DEX; expression of interleukin-1ß: 1.8 [0.34-3.35], P = .01 versus TBI-DEX). CONCLUSIONS: Preanesthetic treatment with DEX suppressed infiltration of MDMs in the hippocampus and ameliorated PND in TBI model mice. Preanesthetic treatment with DEX appears to suppress infiltration of MDMs in the hippocampus and may lead to new treatments for PND in patients with a history of TBI.

Risk factors of cardiac arrest and failure to achieve return of spontaneous circulation during anesthesia: a 20-year retrospective observational study from a tertiary care university hospital.

PURPOSE: There is still a lack of robust data on the epidemiology of cardiac arrest during anesthesia. We investigated the frequency and risk factors of cardiac arrest during anesthesia over the past two decades at a tertiary care university hospital in Japan. METHODS: We retrospectively analyzed 111,851 anesthesia records of patients who underwent surgery under anesthesia between 2000 and 2019. Cardiac arrest cases were classified according to the patient's background, surgical status, main cause and initial rhythm of cardiac arrest, and the presence of the return of spontaneous circulation (ROSC). Univariate and multivariate logistic regression analyses were used to identify the risk factors of cardiac arrest and failure to achieve ROSC. RESULTS: Ninety cardiac arrest cases during anesthesia were identified. The incidence of cardiac arrest was 8.05 per 10,000 anesthetics (95% CI, 6.54-9.90). There were 6 anesthesia-related cardiac arrests and 9 anesthesia-contributory cardiac arrests. The most common cause of cardiac arrest was blood loss. American Society of Anesthesiologists physical status 4-5, emergency surgery, and cardiovascular surgery were identified as independent risk factors of cardiac arrest. American Society of Anesthesiologists physical status 4-5, blood loss-induced cardiac arrest, and non-shockable rhythm were independently associated with failure to achieve ROSC. CONCLUSION: Blood loss was the most common cause of cardiac arrest and blood loss-induced cardiac arrest was independently associated with failure to achieve ROSC. Further improvements in treatment strategies for bleeding may reduce the future incidence of cardiac arrest and death during anesthesia.

Differential effects of remimazolam and propofol on heart rate variability during anesthesia induction.

PURPOSE: The effects of remimazolam on autonomic nervous activity have not been elucidated. We investigated the differential effects of remimazolam and propofol on autonomic nervous activity during anesthesia induction. METHODS: Thirty patients were randomly divided into a remimazolam group or a propofol group for anesthesia induction. Hemodynamics and indices of heart rate variability were recorded before and after anesthesia. Low frequency power (LF; 0.04-0.15 Hz, ms2) and high frequency power (HF; 0.15-0.4 Hz, ms2) were calculated from power spectral density of heart rate variability. LF reflects both sympathetic and parasympathetic activities and HF reflects parasympathetic activity. To investigate the balance between sympathetic and parasympathetic activities, the normalized unit (%) of LF (LF nu) and that of HF (HF nu) were calculated. Changes in LF nu (ΔLF nu) before and after anesthesia (ΔLF nu = LF nu at awake-LF nu after anesthesia) were compared between the groups. RESULTS: Remimazolam and propofol decreased blood pressure and power spectral density of heart rate variability. Remimazolam did not change LF nu and HF nu, while propofol increased LF nu and decreased HF nu (P = 0.020). ΔLF nu in the remimazolam group (1.4 ± 23.6%) were less than that in the propofol group (19.3 ± 22.4%, P = 0.0415). CONCLUSION: Remimazolam and propofol decreased autonomic nervous activity during anesthesia induction. Remimazolam preserved the balance of sympathetic and parasympathetic activities, while propofol modulated it to sympathetic dominance.

Aerosol boxes decrease aerosol exposure only in depressurized rooms during aerosol-generating procedures in a simulation study.

PURPOSE: The aim of this study was to compare aerosol exposure with or without an aerosol box in a pressurized/depressurized room during aerosol-generating procedures using an experimental model. METHODS: Cake flour (aerosol model) was expelled from an advanced life support training mannequin. The primary outcome measure was the number of 0.3-10 µm-sized particles at three locations corresponding to the physician, medical staff, and environmental aerosol exposure levels. The aerosol dispersion was visualized using a high-resolution video. The number of expelled particles was measured after artificial coughing during simulated tracheal intubation and extubation in four situations, with or without an aerosol box in a pressurized or depressurized room (≤ 2.5 Pa). RESULTS: The particles arising from tracheal intubation at the three positions in the four groups differed significantly in size (p < 0.05). The sizes of particles arising from extubation at the physicians' and medical staff's faces in the four groups differed significantly in size (p < 0.05). Post hoc analysis showed that the counts of all particles at the three positions were significantly lower in the depressurized room with an aerosol box than in the pressurized room without an aerosol box during tracheal intubation (p < 0.05 at three positions) and extubation (p < 0.05) at the physician's and medical staff's positions). Visual assessments supported these results. CONCLUSION: The aerosol box decreased the exposure of the aerosol to the physician, medical staff, and environment during aerosol-generating procedures in the depressurized room only.

Usefulness and accuracy of a handheld ultrasound device for epidurssal landmark and depth assessment by anesthesiology residents.

PURPOSE: The aim of this study was to assess the usefulness and accuracy of a handheld ultrasound device (Accuro, Rivanna Medical, Charlottesville, VA, USA) for epidural landmark and depth assessment when epidural anesthesia is performed by residents. METHODS: Patients scheduled to receive epidural anesthesia were randomly assigned to the Accuro group (group A) or control group (group C). In group A, the depth to the epidural space and the appropriate place for epidural insertion according to Accuro was recorded. In group C, epidural anesthesia was performed using a conventional method. The following were recorded and compared between the groups: time from puncture of the Tuohy needle to loss of resistance, number of Tuohy needle redirects, and epidural-related complications. In group A, depth to the epidural space estimated by Accuro (Accuro Depth) and the actual depth measured with a marker on the needle (Needle Depth) were recorded and compared. RESULTS: Sixty patients were enrolled during the study period. There was no significant difference between the groups regarding the median or range of time required to locate the epidural space. The number of Tuohy needle redirects was 0 (0-3) in group A and 1.5 (0-7) in group C (P = 0.012). Accuro Depth was less than Needle Depth [mean difference, 0.85 cm (95% CI-1.10 to - 0.62), SD = 0.62]. CONCLUSIONS: Although there was no significant difference in time from Tuohy needle puncture to loss of resistance, Accuro reduced the number of Tuohy needle redirects and accurately indicated the depth to the epidural space. Accuro may be useful for identifying the needle insertion point and estimating depth to the epidural space when residents perform epidural anesthesia.

Injectate spread in ultrasound-guided inferior alveolar nerve block: a cadaveric study.

PURPOSE: Ultrasound-guided inferior alveolar nerve block (UGIANB) is a mandibular analgesic procedure in which local anesthetic is injected into the pterygomandibular space (PMS). Several studies have reported the clinical efficacy of UGIANB for mandibular surgeries; however, its effective range has never been investigated. We performed a cadaveric study to investigate the success rate of UGIANB injections and to determine whether injected dye could stain the mandibular nerve (MN) trunk and its branches. METHODS: We performed UGIANB on the bilateral faces of 4 Thiel-embalmed cadavers. A needle was advanced to the PMS under ultrasound guidance and 5 mL of dye was injected. The cadaver was dissected and inspected for the presence of dye in the PMS; the range of dye spread to any of the inferior alveolar nerve (IAN), lingual nerve (LN), buccal nerve (BN), mandibular nerve (MN), auriculotemporal nerve (ATN), or facial nerves; and for the presence of intravascular dye. RESULTS: We performed eight UGIANB procedures on four cadavers. Dye was observed in the PMS in 7/8 injections. Staining was observed in all IAN, LN, and BNs that could be identified at dissection. No MN or auriculotemporal nerves (ATNs) were stained in any injections. No intravascular dye was observed in any injections. CONCLUSIONS: UGIANB can administer anesthetic into the PMS with high accuracy. UGIANB injections reached the IAN, LN, and BNs, but did not reach the MN or ATNs located outside the PMS. The findings of this cadaveric study indicate that UGIANB can provide sufficient analgesia for mandibular surgeries.

Efficacy of Automatic Retention Pressure of a Double-Lumen Tube Cuff: An Artificial Intubation Model.

BACKGROUND: The movement of a double-lumen endotracheal tube (DLT) out of its appropriate position during thoracic surgery can result in the loss of one-lung ventilation (OLV), especially during pulmonary resection and node dissection. Our study aimed to validate the efficacy of automatic retention pressure control of the DLT bronchial cuff in maintaining OLV in an artificial intubation model. MATERIALS AND METHODS: A 35-Fr left-sided DLT was intubated to the left main bronchus in an intubation simulator and connected to an anesthesia machine. The inspiratory volume, respiratory rate, and inspiratory-expiratory ratio were set at 500 mL, 12 times/min, and 1:2, respectively. A 1-kg right main bronchial traction in the lateral right was provided after OLV was established. SmartCuff (Smiths Medical, Minneapolis, Minnesota, USA) was used to maintain cuff pressure. The efficacy of retention pressure with SmartCuff (Group S) and without SmartCuff (Group WS) was compared. The primary outcome was the rate of tidal volume (TV) reduction following bronchial traction in the two groups. RESULTS: The TVs were 289.8 ± 28.9 mL and 242.8 ± 31.9 mL in Group S and Group WS, respectively (P = 0.003). The rate of TV reduction after bronchial traction was significantly lower in Group S (29 ± 5%) than in Group WS (43 ± 6%) (P < 0.001). CONCLUSIONS: Automatic retention pressure control of the DLT bronchial cuff improves the rate of TV reduction during right main bronchial traction in an artificial intubation model. Continuous retention cuff pressure may be useful in maintaining OLV during thoracic surgery.

Sudden cardiac arrest associated with myxedema coma due to undiagnosed hypothyroidism: a case report.

BACKGROUND: Myxedema coma, which occurs due to hypothyroidism, is a rare and life-threatening condition. Some patients have hemodynamic dysfunction, which consequently leads to cardiac arrest. The rarity of this condition makes it difficult to determine the cause of cardiac arrest. It is important to diagnose myxedema coma based on clinical findings, including physical examination and laboratory parameters. We present a case of undiagnosed and untreated hypothyroidism that initially caused myxedema coma and then led to cardiac arrest. CASE PRESENTATION: A 56-year-old woman who had no medical history was transferred to our hospital for the management of return of spontaneous circulation due to sudden cardiac arrest. Findings of laboratory tests revealed that she had hypothyroidism. On physical examination, she was found to have a puffy face, thin eyebrows, and severe systemic non-pitting edema. Therefore, the patient was clinically diagnosed with myxedema coma, which was the cause of cardiac arrest. She was treated with thyroid hormone and hydrocortisone, resulting in improvement in her general condition, except for the neurological dysfunction. CONCLUSIONS: This case suggests that myxedema coma is caused by undiagnosed and untreated hypothyroidism, leading to sudden cardiac arrest. Our findings are useful in the differential diagnosis of hypothyroidism based on characteristic physical examination findings. Clinicians should be aware of the differential diagnosis of myxedema coma based on findings from physical examination and laboratory testing of thyroid function, and the treatment should be started immediately.