The role of astrocytic γ-aminobutyric acid in the action of inhalational anesthetics.

BACKGROUND: Inhalational anesthetics target the inhibitory extrasynaptic γ-aminobutyric acid type A (GABAA) receptors. Both neuronal and glial GABA mediate tonic inhibition of the extrasynaptic GABAA receptors. However, the role of glial GABA during inhalational anesthesia remains unclear. This study aimed to evaluate whether astrocytic GABA contributes to the action of different inhalational anesthetics. METHODS: Gene knockout of monoamine oxidase B (MAOB) was used to reduce astrocytic GABA levels in mice. The hypnotic and immobilizing effects of isoflurane, sevoflurane, and desflurane were assessed by evaluating the loss of righting reflex (LORR) and tail-pinch withdrawal response (LTWR) in MAOB knockout and wild-type mice. Minimum alveolar concentration (MAC) for LORR, time to LORR, MAC for LTWR and time to LTWR of isoflurane, sevoflurane, and desflurane were assessed. RESULTS: Time to LORR and time to LTWR with isoflurane were significantly longer in MAOB knockout mice than in wild-type mice (P < 0.001 and P = 0.032, respectively). Time to LORR with 0.8 MAC of sevoflurane was significantly longer in MAOB knockout mice than in wild-type mice (P < 0.001), but not with 1.0 MAC of sevoflurane (P=0.217). MAC for LTWR was significantly higher in MAOB knockout mice exposed to sevoflurane (P < 0.001). With desflurane, MAOB knockout mice had a significantly higher MAC for LORR (P = 0.003) and higher MAC for LTWR (P < 0.001) than wild-type mice. CONCLUSIONS: MAOB knockout mice showed reduced sensitivity to the hypnotic and immobilizing effects of isoflurane, sevoflurane, and desflurane. Behavioral tests revealed that the hypnotic and immobilizing effects of inhalational anesthetics would be mediated by astrocytic GABA.

Comparison of the effects of paratracheal pressure and cricoid pressure on placement of the i-gel® supraglottic airway: a randomized clinical trial.

PURPOSE: Anesthesiologists can use supraglottic airway devices as a rescue technique for failed intubation even in patients with an increased risk of gastric regurgitation. In this randomized study, we aimed to evaluate the effects of cricoid pressure and paratracheal pressure on placement of the i-gel® (Intersurgical Ltd., Wokingham, Berkshire, UK). METHODS: After induction of anesthesia in 76 adult patients, we inserted the i-gel under paratracheal or cricoid pressure, and assessed the success rate of i-gel insertion, resistance during insertion, time required for insertion, accuracy of the insertion location, tidal volumes, and peak inspiratory pressure with or without each maneuver after i-gel insertion. RESULTS: The overall success rate of insertion was significantly higher under paratracheal pressure than under cricoid pressure (36/38 [95%] vs 27/38 [71%], respectively; difference, 24%; 95% confidence interval [CI], 8 to 40; P = 0.006]. Resistance during insertion was significantly lower under paratracheal pressure than under cricoid pressure (P < 0.001). The time required for insertion was significantly shorter under paratracheal pressure than under cricoid pressure (median [interquartile range], 18 [15-23] sec vs 28 [22-38] sec, respectively; difference in medians, -10; 95% CI, -18 to -4; P < 0.001). Fibreoptic examination of the anatomical alignment of the i-gel in the larynx revealed no significant difference in the accuracy of the insertion location between the two maneuvers (P = 0.31). The differences in tidal volume and peak inspiratory pressure with or without the maneuvers were significantly lower with paratracheal pressure than with cricoid pressure (P = 0.003, respectively). CONCLUSIONS: Insertion of the i-gel supraglottic airway was significantly more successful, easier, and faster while applying paratracheal pressure than cricoid pressure. STUDY REGISTRATION: ClinicalTrials.gov (NCT05377346); first submitted 11 May 2022.

RéSUMé: OBJECTIF: Les anesthésiologistes peuvent utiliser des dispositifs supraglottiques comme technique de sauvetage en cas d'échec de l'intubation, même chez les personnes présentant un risque accru de régurgitation gastrique. Dans cette étude randomisée, nous avons cherché à évaluer les effets de la pression cricoïdienne et de la pression paratrachéale sur le positionnement du dispositif i-gel® (Intersurgical Ltd., Wokingham, Berkshire, Royaume-Uni). MéTHODE: Après l'induction de l'anesthésie chez 76 adultes, nous avons inséré l'i-gel en utilisant une pression paratrachéale ou cricoïdienne, et avons évalué le taux de réussite de l'insertion de l'i-gel, la résistance pendant l'insertion, le temps nécessaire à l'insertion, la précision de l'emplacement d'insertion, les volumes courants ainsi que la pression inspiratoire maximale avec ou sans chacune des manœuvres après l'insertion de l'i-gel. RéSULTATS: Le taux global de réussite de l'insertion était significativement plus élevé avec une pression paratrachéale qu'avec une pression cricoïdienne (36/38 [95 %] vs 27/38 [71 %], respectivement; différence, 24 %; intervalle de confiance [IC] à 95 %, 7,6 à 39,8; P = 0,006]. La résistance lors de l'insertion était significativement plus faible en utilisant une pression paratrachéale par rapport à une pression cricoïdienne (P < 0,001). Le temps nécessaire à l'insertion était significativement plus court après avoir exercé une pression paratrachéale plutôt que cricoïdienne (médiane [écart interquartile], 18,4 [15,3­23,1] secondes vs 28,4 [22,3 à 37,8] secondes, respectivement; différence dans les médianes, −10,0; IC 95 %, −18,4 à −3,6; P < 0,001). L'examen par fibre optique de l'alignement anatomique de l'i-gel dans le larynx n'a révélé aucune différence significative dans la précision de l'emplacement d'insertion entre les deux manœuvres (P = 0,31). Les différences de volume courant et de pression inspiratoire maximale avec ou sans les manœuvres étaient significativement plus faibles avec la pression paratrachéale qu'avec la pression cricoïdienne (P = 0,003, respectivement). CONCLUSION: L'insertion du dispositif supraglottique i-gel a été significativement plus réussie, plus facile et plus rapide lors de l'application d'une pression paratrachéale que d'une pression cricoïdienne. ENREGISTREMENT DE L'éTUDE: ClinicalTrials.gov (NCT05377346); soumis pour la première fois le 11 mai 2022.

Usefulness of video laryngoscopy in tracheal intubation at thyroid surgical position for intraoperative neuromonitoring.

This observational study aimed to compare the glottic view between video and direct laryngoscopy for tracheal intubation in the surgical position for thyroid surgery with intraoperative neuromonitoring. Patients scheduled for elective thyroid surgery with intraoperative neuromonitoring were enrolled. After the induction of anesthesia, patients were positioned in the thyroid surgical posture with a standard inclined pillow under their head and back. An investigator assessed the glottic view using the percentage of glottic opening (POGO) scale and the modified Cormack-Lehane grade in direct laryngoscopy and then video laryngoscopy sequentially while using the same McGRATH™ MAC video laryngoscope at once, with or without external laryngeal manipulation, at the surgical position. A total of thirty-nine patients were participated in this study. Without external laryngeal manipulation, the POGO scale significantly improved during video laryngoscopy compared to direct laryngoscopy in the thyroid surgical position (60.0 ± 38.2% vs. 22.4 ± 23.8%; mean difference (MD) 37.6%, 95% confidence interval (CI) = [29.1, 46.0], P < 0.001). Additionally, with external laryngeal manipulation, the POGO scale showed a significant improvement during video laryngoscopy compared to direct laryngoscopy (84.6 ± 22.9% vs. 58.0 ± 36.3%; MD 26.7%, 95% CI = [18.4, 35.0] (P < 0.001). The superiority of video laryngoscopy was also observed for the modified Cormack-Lehane grade. In conclusion, video laryngoscopy with the McGRATH™ MAC video laryngoscope, when compared to direct laryngoscopy with it, improved the glottic view during tracheal intubation in the thyroid surgical position. This enhancement may potentially facilitate the proper placement of the electromyography tracheal tube and prevent tube displacement due to positional change for thyroid surgery.

Effect of sputtering power on the physical properties of amorphous SiO2-doped InZnO transparent conductive oxide.

In order to control the optical and electrical properties of the transparent conductive oxide, the radio frequency (RF) sputtering power was changed from 30 to 40, 50, and 60 W. To optimize the power condition of the SiInZnO (SIZO) layer, we changed the sputtering power from 30 to 60 W, systematically. The chemical properties of the SIZO layer were analyzed using X-ray photoelectron spectroscopy (XPS). XPS proved that this change is dominant in thickness. In order to fabricate the SIZO transparent conducting oxide (TCO) with the optimized power of 50 W, the transmittance of 99.1% at 550 nm and the figure of merit of 12.4×10-3 Ω -1 were obtained.

A bench study on the prevention of lung-to-lung aspiration with double-lumen endobronchial tubes and bronchial blockers.

Effective lung isolation prevents lung-to-lung aspiration during thoracotomy for the management of hemoptysis. Double-lumen endobronchial tubes (DLT) and bronchial blockers are commonly used for lung separation during thoracic surgery. In this study, the fluid-sealing characteristics of the endobronchial cuffs of three different commercially available DLTs (Broncho-Cath with a polyvinylchloride cuff, Broncho-Cath with a polyurethane cuff, and Human Broncho with a silicone cuff) and two different bronchial blockers (Arndt and Coopdech bronchial blockers) were evaluated using a benchtop model. The lateral decubitus position for the surgical management of bleeding from the right lung was simulated. The artificial tracheobronchial tree was placed horizontally, with the left bronchus in the dependent position and the right bronchus in the non-dependent position. In the DLT experiments, the tracheobronchial tree was intubated with left-sided DLTs, and the endobronchial cuff was inflated to maintain the intracuff pressure at 25 cmH2O. In the experiments with bronchial blockers, each bronchial blocker was inserted into the right bronchus, and the endobronchial cuff was inflated to seal the main bronchus. A fluid leakage test around the endobronchial cuff was performed using three different types of DLT (size 35, 37, and 41 Fr, each) and two different types of bronchial blockers (9 Fr). The 5 mL of colored water was poured into the right bronchus to simulate the blood flow from the operative side, and the times to the first and 100% leakage around the endobronchial cuff were recorded. Each bronchial blocker showed significantly less leakage over time than the other DLTs (P < 0.05). Fluid was not fully leaked around the cuffs for 24 h with either bronchial blocker. The times to first and 100% leakage were not significantly different among different types of DLTs. The times to first and 100% leakage did not also differ among the three different sizes of each type DLT. There was no significant difference in the time to first leakage around the endobronchial cuffs between Arndt and Coopdech bronchial blockers. Bronchial blockers provided a more effective seal against lung-to-lung aspiration than DLTs in the lateral decubitus position for thoracotomy in the benchtop model.

Korean clinical practice guidelines for diagnostic and procedural sedation.

Safe and effective sedation depends on various factors, such as the choice of sedatives, sedation techniques used, experience of the sedation provider, degree of sedation-related education and training, equipment and healthcare worker availability, the patient's underlying diseases, and the procedure being performed. The purpose of these evidence-based multidisciplinary clinical practice guidelines is to ensure the safety and efficacy of sedation, thereby contributing to patient safety and ultimately improving public health. These clinical practice guidelines comprise 15 key questions covering various topics related to the following: the sedation providers; medications and equipment available; appropriate patient selection; anesthesiologist referrals for high-risk patients; pre-sedation fasting; comparison of representative drugs used in adult and pediatric patients; respiratory system, cardiovascular system, and sedation depth monitoring during sedation; management of respiratory complications during pediatric sedation; and discharge criteria. The recommendations in these clinical practice guidelines were systematically developed to assist providers and patients in sedation-related decision making for diagnostic and therapeutic examinations or procedures. Depending on the characteristics of primary, secondary, and tertiary care institutions as well as the clinical needs and limitations, sedation providers at each medical institution may choose to apply the recommendations as they are, modify them appropriately, or reject them completely.

Effect of paratracheal pressure on the effectiveness of mask ventilation in obese anesthetized patients: a randomized, cross-over study.

Paratracheal pressure has been recently suggested to compress and occlude the upper esophagus at the lower left paratracheal region to prevent gastric regurgitation alternative to cricoid pressure. It also prevents gastric insufflation. The aim of this randomized cross-over study was to investigate the effectiveness of paratracheal pressure on mask ventilation in obese anesthetized paralyzed patients. After the induction of anesthesia, two-handed mask ventilation was initiated in a volume-controlled mode with a tidal volume of 8 mL kg‒1 based on ideal body weight (IBW), a respiratory rate of 12 breaths min- 1, and positive end-expiratory pressure of 10 cmH2O. Expiratory tidal volume and peak inspiratory pressure were recorded alternately with or without the application of 30 Newtons (approximately 3.06 kg) paratracheal pressure during a total of 16 successive breaths over 80 s. Association of patient characteristics with the effectiveness of paratracheal pressure on mask ventilation, defined as the difference in expiratory tidal volume between the presence or absence of paratracheal pressure were evaluated. In 48 obese anesthetized paralyzed patients, expiratory tidal volume was significantly higher with the application of paratracheal pressure than without paratracheal pressure [496.8 (74.1) mL kg- 1 of IBW vs. 403.8 (58.4) mL kg- 1 of IBW, respectively; P < 0.001]. Peak inspiratory pressure was also significantly higher with the application of paratracheal pressure compared to that with no paratracheal pressure [21.4 (1.2) cmH2O vs. 18.9 (1.6) cmH2O, respectively; P < 0.001]. No significant association was observed between patient characteristics and the effectiveness of paratracheal pressure on mask ventilation. Hypoxemia did not occur in any of the patients during mask ventilation with or without paratracheal pressure. The application of paratracheal pressure significantly increased both the expiratory tidal volume and peak inspiratory pressure during face-mask ventilation with a volume-controlled mode in obese anesthetized paralyzed patients. Gastric insufflation was not evaluated in this study during mask ventilation with or without paratracheal pressure.

Comparison of the effect of sevoflurane and propofol on the optic nerve sheath diameter in patients undergoing middle ear surgery.

PURPOSE: During middle ear surgery, the patient's head is turned away from the surgical site, which may increase the intracranial pressure. Anesthetics also affect the intracranial pressure. The optic nerve sheath diameter (ONSD) measured using ultrasonography is a reliable marker for estimating the intracranial pressure. This aim of this study was to investigate the effect of sevoflurane and propofol on the ONSD in patients undergoing middle ear surgery. METHODS: Fifty-eight adult patients were randomized into sevoflurane group (n = 29) or propofol group (n = 29). The ONSD was measured using ultrasound after anesthesia induction before head rotation (T0), and at the end of surgery (T1). The occurrence and severity of postoperative nausea and vomiting (PONV) were assessed 1 h after the surgery. RESULTS: The ONSD was significantly increased from T0 to T1 in the sevoflurane group [4.3 (0.5) mm vs. 4.9 (0.6) mm, respectively; P < 0.001] and the propofol group [4.2 (0.3) mm vs. 4.8 (0.5) mm, respectively; P < 0.001]. No significant difference was observed in the ONSD at T0 (P = 0.267) and T1 (P = 0.384) between the two groups. The change in the ONSD from T0 to T1 was not significantly different between the sevoflurane and propofol groups [0.6 (0.4) mm vs. 0.6 (0.3) mm, respectively; P = 0.972]. The occurrence and severity of PONV was not significantly different between the sevoflurane and propofol groups (18% vs. 0%, respectively; P = 0.053). CONCLUSION: The ONSD was significantly increased during middle ear surgery. No significant difference was observed in the amount of ONSD increase between the sevoflurane and propofol groups.

Novel potent blockers for TWIK-1/TREK-1 heterodimers as potential antidepressants.

TREK-1 (TWIK-related potassium channel-1) is a subunit of the two-pore domain potassium (K2p) channel and is widely expressed in the brain. TREK-1 knockout mice were shown to have antidepressant-like effects, providing evidence for the channel's potential as a therapeutic target. However, currently there is no good pharmacological inhibitor specifically targeting TREK-1 containing K2p channels that also displays similar antidepressant-like effects. Here, we sought to find selective and potent inhibitors for TREK-1 related dimers both in vitro and in vivo. We synthesized and evaluated 2-hydroxy-3-phenoxypropyl piperidine derivatives yielding a library from which many TREK-1 targeting candidates emerged. Among these, hydroxyl-phenyl- (2a), piperidino- (2g), and pyrrolidino- (2h) piperidinyl substituted compounds showed high potencies to TREK-1 homodimers with significant antidepressant-like effects in forced swim test and tail suspension test. Interestingly, these compounds were found to have high potencies to TWIK-1/TREK-1 heterodimers. Contrastingly, difluoropiperidinyl-4-fluorophenoxy (3e) and 4-hydroxyphenyl-piperidinyl-4-fluorophenoxy (3j) compounds had high potencies to TREK-1 homodimer but lower potency to TWIK-1/TREK-1 heterodimers without significant antidepressant-like effects. We observed positive correlation between inhibition potency to TWIK-1/TREK-1 and immobility time, and no correlation between inhibition potency to TREK-1 homodimer and immobility time. This was consistent with molecular docking simulations of selected compounds to TREK-1 homodimeric and TWIK-1/TREK-1 heterodimeric models. Existing antidepressant fluoxetine was also found to potently inhibit TWIK-1/TREK-1 heterodimers. Our study reveals novel potent TWIK-1/TREK-1 inhibitors 2a, 2g, and 2h as potential antidepressants and suggest that the TWIK-1/TREK-1 heterodimer could be a potential novel molecular therapeutic target for antidepressants.

Effect of head and neck positions on tracheal intubation using a McGRATH MAC video laryngoscope: A randomised, prospective study.

BACKGROUND: Different head and neck positions may affect video laryngoscopy in terms of laryngeal exposure, intubation difficulty, advancement of the tracheal tube into the glottis and the occurrence of palatopharyngeal mucosal injury. OBJECTIVE: We investigated the effects of simple head extension, head elevation without head extension and the sniffing position on tracheal intubation using a McGRATH MAC video laryngoscope. DESIGN: A randomised, prospective study. SETTING: Medical centre governed by a university tertiary hospital. PATIENTS: A total of 174 patients undergoing general anaesthesia. METHODS: Patients were randomly allocated to one of three groups: simple head extension (neck extension without a pillow), head elevation only (head elevation with a pillow of 7 cm and no neck extension) and sniffing position (head elevation with a pillow of 7 cm and neck extension). MAIN OUTCOMES: During tracheal intubation using a McGRATH MAC video laryngoscope in three different head and neck positions, we assessed intubation difficulty by several methods: a modified intubation difficulty scale score, time taken for tracheal intubation, glottic opening, number of intubation attempts, requirements for other manoeuvres (lifting force or laryngeal pressure) for laryngeal exposure and advancement of the tracheal tube into the glottis. The occurrence of palatopharyngeal mucosal injury was evaluated after tracheal intubation. RESULTS: Tracheal intubation was significantly easier in the head elevation group than in the simple head extension ( P  = 0.001) and sniffing positions ( P  = 0.011). Intubation difficulty did not differ significantly between the simple head extension and sniffing positions ( P  = 0.252). The time taken for intubation in the head elevation group was significantly shorter than that in the simple head extension group ( P  < 0.001). A lifting force or laryngeal pressure was required less frequently for tube advancement into the glottis in the head elevation group than in the simple head extension ( P  = 0.002) and sniffing position groups ( P  = 0.012). The need for a lifting force or laryngeal pressure for tube advancement into the glottis was not significantly different between the simple head extension and sniffing positions ( P  = 0.498). Palatopharyngeal mucosal injury occurred less frequently in the head elevation group than in the simple head extension group ( P  = 0.009). CONCLUSION: The head elevation position facilitated tracheal intubation using a McGRATH MAC video laryngoscope compared with a simple head extension or sniffing position. TRIAL REGISTRY NUMBER: ClinicalTrials.gov (NCT05128968).

Comparison of the needle tip location with the operator's position during ultrasound-guided internal jugular vein catheterization: A randomized controlled study.

OBJECTIVE: We hypothesized that when a right-handed operator catheterizes the left internal jugular vein (IJV), the tip of the needle might be positioned closer to the center of the vessel after puncture if the operator is standing in the patient's left axillary line, rather than standing cephalad to the patient. METHODS: The study randomly allocated 44 patients undergoing elective surgery under general anesthesia with planned left central venous catheterization to either conventional (operator stood cephalad to the patient) or intervention (operator stood in the patient's axillary line) groups. The left IJV was catheterized by 18 anesthesiologists. The distance between the center of the vessel and the needle tip, first-attempt success rate, and procedure time were compared. RESULTS: The distance from the needle tip to the center of the IJV after needle puncture was 3.5 (1.9-5.5) and 3.2 (1.7-4.9) cm in the conventional and intervention groups, respectively (P = .47). The first-attempt success rate was significantly higher in the intervention group (100% vs 68.2%, P = .01). Overall time to successful guidewire insertion was faster in the intervention group (P = .007). CONCLUSIONS: There was no significant difference in needle tip position when the right-handed operator was standing in the patient's left axillary line compared to standing cephalad to the patient during left IJV catheterization. However, it increased the first-attempt success rate and reduced the overall time for guidewire insertion.

Effectiveness of Cricoid and Paratracheal Pressures in Occluding the Upper Esophagus Through Induction of Anesthesia and Videolaryngoscopy: A Randomized, Crossover Study.

BACKGROUND: Maneuvers for preventing passive regurgitation of gastric contents are applied to effectively occlude the esophagus throughout rapid sequence induction and intubation. The aim of this randomized, crossover study was to investigate the effectiveness of cricoid and paratracheal pressures in occluding the esophagus through induction of anesthesia and videolaryngoscopy. METHODS: After the induction of anesthesia in 40 adult patients, the location of the esophageal entrance relative to the glottis and location of the upper esophagus relative to the trachea at the low paratracheal region were assessed using an ultrasonography, and the outer diameter of the esophagus was measured on ultrasound before and during application of cricoid and paratracheal pressures of 30 N. Then, videolaryngoscopy was performed with the application of each pressure. During videolaryngoscopy, location of the esophageal entrance relative to the glottis under cricoid pressure was examined on the screen of videolaryngoscope, and the upper esophagus under paratracheal pressure was evaluated using ultrasound. The occlusion rate of the esophagus, and the best laryngeal view using the percentage of glottic opening scoring system were also assessed during videolaryngsocopy. Esophageal occlusion under each pressure was determined by inserting an esophageal stethoscope into the esophagus. If the esophageal stethoscope could not be advanced into the esophagus under the application of each pressure, the esophagus was regarded to be occluded. RESULTS: During videolaryngoscopy, esophagus was occluded in 40 of 40 (100%) patients with cricoid pressure and 23 of 40 (58%) patients with paratracheal pressure (difference, 42%; 95% confidence interval, 26-58; P < .001). Both cricoid and paratracheal pressures significantly decreased the diameter of the esophagus compared to no intervention in the anesthetized paralyzed state ( P < .001, respectively). Ultrasound revealed that the compressed esophagus by paratracheal pressure in the anesthetized paralyzed state was partially released during videolaryngoscopy in 17 of 40 patients, in whom esophageal occlusion was unsuccessful. The best laryngeal view was not significantly different among the no intervention, cricoid pressure, and paratracheal pressure (77 [29] % vs 79 [30] % vs 76 [31] %, respectively; P = .064). CONCLUSIONS: The occlusion of the upper esophagus defined by inability to pass an esophageal stethoscope was more effective with cricoid pressure than with paratracheal pressure during videolaryngoscopy, although both cricoid and paratracheal pressures reduced the diameter of the esophagus on ultrasound in an anesthetized paralyzed state.

Association Between Anesthetics and Postoperative Delirium in Elderly Patients Undergoing Spine Surgery: Propofol Versus Sevoflurane.

STUDY DESIGNS: Retrospective Observational StudyObjectives: To compare the incidence of POD after propofol- and sevoflurane-based anesthesia in elderly patients undergoing spine surgery. METHODS: In this study, the medical records of elderly patients ≥ 65 years of age who underwent spine surgery under total intravenous anesthesia with propofol or inhalational anesthesia with sevoflurane were reviewed. The primary outcome was the incidence of POD after propofol- and sevoflurane-based anesthesia. Secondary outcomes included postoperative 30-day complications, length of postoperative hospital stay, associations of patient characteristics, and surgery- and anesthesia-related data with the development of POD, and associations of anesthetics with clinical outcomes such as postoperative 30-day complications, and length of postoperative hospital stay. RESULTS: Of the 281 patients, POD occurred in 29 patients (10.3%). POD occurred more frequently in the sevoflurane group than in the propofol group (15.7% vs. 5.0%, respectively; P=.003). The multivariable logistic regression analysis showed that sevoflurane-based anesthesia was associated with an increased risk of POD compared with propofol-based anesthesia (odds ratio [OR], 4.120; 95% confidence interval [CI], 1.549-10.954; P = .005), whereas anesthetics were not associated with postoperative 30-day complications and the length of postoperative hospital stay. Older age (OR, 1.242 CI, 1.130-1.366; P < .001) and higher mean pain score at postoperative day 1 (OR, 1.338 CI, 1.056-1.696; P = .016) were also associated with an increased risk of POD. CONCLUSIONS: Propofol-based anesthesia was associated with a lower incidence of POD than sevoflurane-based anesthesia in elderly patients after spine surgery.

Evaluation of the conventional and modified aerosol boxes during tracheal intubation in normal and difficult airways: a randomized, crossover, manikin simulation study.

The aim of this study was to evaluate conventional and modified aerosol boxes in terms of intubation time, first-pass intubation success, and mouth-to-mouth distance between the laryngoscopist and patient during tracheal intubation in simulated patients with normal and difficult airways. Sixteen anesthesiologists performed tracheal intubations with direct laryngoscope or three different videolaryngoscopes (McGRATH MAC videolaryngoscope, C-MAC videolaryngoscope, and Pentax-AWS) without an aerosol box or with a conventional or a modified aerosol boxes in simulated manikins with normal and difficult airways. Intubation time, first-pass intubation success, and mouth-to-mouth distance during tracheal intubation were recorded. Compared to no aerosol box, the use of a conventional aerosol box significantly increased intubation time in both normal and difficult airways (Bonferroni-corrected P-value (Pcorrected) = 0.005 and Pcorrected = 0.003, respectively). Intubation time was significantly shorter with the modified aerosol box than with the conventional one for both normal and difficult airways (Pcorrected = 0.003 and Pcorrected = 0.011, respectively). However, no significant differences were found in intubation time between no aerosol box and the modified aerosol box for normal and difficult airways (Pcorrected = 0.336 and Pcorrected = 0.112, respectively). The use of conventional or modified aerosol boxes significantly extended the mouth-to-mouth distances compared to not using an aerosol box during tracheal intubation with each laryngoscope (all Pcorrected < 0.05), and the distances were not different between the conventional and modified boxes in normal and difficult airways. The use of modified aerosol box did not increase intubation time and could help maintain a distance from the simulated patients with normal and difficult airways.

Assessment of the 50 % and 95 % effective paratracheal forces for occluding the esophagus in anesthetized patients.

This study aimed to evaluate the 50% and 95% effective paratracheal forces for occluding the esophagus in anesthetized patients. In 46 anesthetized patients, the upper esophagus was examined using ultrasonography, and the lower paratracheal area over the esophagus just above the clavicle was marked. Manual paratracheal force was applied over that area using a novel pressure sensing device set-up. In the first patient, a 20 N paratracheal force was applied, and the patency of the esophagus was assessed by advancing the esophageal stethoscope. Unsuccessful advancement of the esophageal stethoscope was considered an effective paratracheal force. If advancement of the esophageal stethoscope was successful, the paratracheal force was increased by 2 N for the next patient, and if it was unsuccessful, the force was decreased by 2 N for the next patient. These sequential tests were performed using 12- and 18-Fr esophageal stethoscopes, respectively. According to Dixon and Mood method, the 50% effective paratracheal force (confidence interval) was 18.4 (17.5‒19.3) N with the use of a 12-Fr esophageal stethoscope and 12.8 (11.0‒14.6) N with the use of an 18-Fr esophageal stethoscope. Using probit regression analysis, the 50% and 95% effective paratracheal forces were 18.4 (16.8‒19.6) N and 20.6 (19.4‒27.9) N, respectively, with the use of a 12-Fr esophageal stethoscope, and 12.4 (8.3‒14.4) N and 16.9 (14.7‒37.3) N, respectively, with the use of an 18-Fr esophageal stethoscope. Our findings suggest a guide for applying paratracheal force during rapid sequence induction and tracheal intubation.

Comparison of the Conventional Downward and Modified Upward Laryngeal Handshake Techniques to Identify the Cricothyroid Membrane: A Randomized, Comparative Study.

BACKGROUND: Accurate identification of the cricothyroid membrane is crucial for successful cricothyroidotomy. The aim of this study was to compare the conventional downward and modified upward laryngeal handshake techniques in terms of accuracy to identify the cricothyroid membrane in nonobese female patients. METHODS: In 198 anesthetized female patients, the cricothyroid membrane was identified by either the conventional downward laryngeal handshake technique (n = 99) or the modified upward laryngeal handshake technique (n = 99). According to the conventional downward laryngeal handshake technique, the cricothyroid membrane was identified by palpating the neck downward from the greater cornu of the hyoid bone, thyroid laminae, and cricoid cartilage. According to the modified upward laryngeal handshake technique, the cricothyroid membrane was located by moving up from the sternal notch. The primary outcome was the accuracy of identifying the cricothyroid membrane. Secondary outcomes included the accuracy of midline identification and time taken to locate what participants believed to be the cricothyroid membrane. The primary and secondary outcomes according to the technique were analyzed using generalized estimating equations. RESULTS: The cricothyroid membrane could be identified more accurately by the modified upward laryngeal handshake technique than by the conventional downward technique (84% vs 56%, respectively; odds ratio [OR], 4.36; 95% confidence interval [CI], 2.13-8.93; P < .001). Identification of the midline was also more accurate by the modified laryngeal handshake than by the conventional technique (96% vs 83%, respectively; OR, 4.98; 95% CI, 1.65-15.01; P = .004). The time taken to identify the cricothyroid membrane was not different between the conventional and modified techniques (20.2 [16.2-26.6] seconds vs 19.0 [14.5-26.4] seconds, respectively; P = .83). CONCLUSIONS: The modified upward laryngeal handshake technique that involved tracing the trachea and laryngeal structures upward from the sternal notch was more accurate in identifying the cricothyroid membrane than the conventional downward technique in anesthetized female patients.

Effect of head and shoulder positioning on the cross-sectional area of the subclavian vein in obese subjects.

OBJECTIVE: Head and shoulder positioning may affect cross-sectional area (CSA) and location of the subclavian vein (SCV). We investigated the CSA of the SCV and the depth of the SCV, depending on the head and shoulder positions. METHODS: In 24 healthy obese volunteers, the short axis ultrasound images of the SCV and adjacent structures were obtained in three different head positions (neutral, 30° turned to the contralateral side, and 30° turned to the ipsilateral side) and two different shoulder positions (neutral and lowered). Images of the right and left SCVs were obtained in the supine and Trendelenburg positions. Subsequently, the CSA and depth of the SCV were measured. RESULTS: Significant differences were found in the CSA of the SCV in different head positions (30° turned to contralateral side vs. neutral: -0.06 cm2, 95% confidence interval [CI], -0.10 to -0.02; Pcorrected = 0.002, 30° turned to contralateral side vs. 30° turned to ipsilateral side: -0.16 cm2, 95% CI, -0.22 to -0.11; Pcorrected < 0.001, Neutral vs. 30° turned to ipsilateral side: -0.10 cm2, 95% CI, -0.14 to -0.07; Pcorrected < 0.001). The CSA of the SCV was significantly different, depending on shoulder positions (neutral vs. lowered: 0.44 cm2, 95% CI, 0.33 to 0.54; Pcorrected < 0.001), and body position (supine vs. Trendelenburg: -0.15 cm2, 95% CI, -0.19 to -0.12; Pcorrected < 0.001). However, the depth of the SCV did not differ with respect to head, shoulder, and body positions. CONCLUSIONS: Ipsilateral 30° head rotation, neutral shoulder position, and Trendelenburg position significantly enhanced the CSA of the SCV in obese participants.

Self-sealing hyaluronic acid-coated 30-gauge intravitreal injection needles for preventing vitreous and drug reflux through needle passage.

Self-sealing hyaluronic acid (HA)-coated self-sealing 30-gauge needles exhibiting instant leakage prevention of intravitreal humor and injected drug were developed in this study. Ninety New Zealand rabbits were used in this study. We assessed dye regurgitation in intravitreal ICG dye injections using HA-coated needles (HA needle group) and conventional needles (control group). Vitreous humor levels of anti-vascular endothelial growth factor (VEGF) were compared between groups one, three, and seven days after intravitreal bevacizumab (0.016 mL) injections. Expression levels of inflammatory cytokines in the aqueous humor and vitreous humor, including prostaglandin E2 (PGE2), interferon-γ, tumor necrosis factor-α, interleukin (IL)-1ß, IL-4, IL-6, IL-17, and IL-8, were compared between HA needle, control, and normal (in which intravitreal injection was not performed) groups following 12 intravitreal injections over a period of one week. In the HA needle group, HA remained at the injection site and blocked the hole after intravitreal injection. Dye regurgitation occurred significantly less frequently in the HA needle group (16.7%) than the control group (55.6%) after intravitreal ICG dye injection. Meanwhile, vitreous anti-VEGF levels were markedly higher in the HA needle group than the control group one and three days after intravitreal bevacizumab injections. After 12 intravitreal injections, expression levels of aqueous and vitreous IL-8 significantly increased in the control group compared to the HA needle and normal groups. Conversely, there were no significant differences in the expression of the other seven cytokines among the three groups. Intravitreal injections using HA-coated self-sealing 30-gauge needles can block the outflow of vitreous humor and drugs through the needle passage.

Effect of Paratracheal Pressure on the Glottic View During Direct Laryngoscopy: A Randomized Double-Blind, Noninferiority Trial.

BACKGROUND: Cricoid pressure has been used as a component of the rapid sequence induction and intubation technique. However, concerns have been raised regarding the effectiveness and safety of cricoid pressure. Paratracheal pressure, a potential alternative to cricoid pressure to prevent regurgitation of gastric contents or aspiration, has been studied to be more effective to cricoid pressure in preventing gastric insufflation during positive pressure ventilation. However, to adopt paratracheal compression into our practice, adverse effects including its effect on the glottic view during direct laryngoscopy should be studied. We conducted a randomized, double-blind, noninferiority trial comparing paratracheal and cricoid pressures for any adverse effects on the view during direct laryngoscopy, together with other secondary outcome measures. METHODS: In total, 140 adult patients undergoing general anesthesia randomly received paratracheal pressure (paratracheal group) or cricoid pressure (cricoid group) during anesthesia induction. The primary end point was the incidence of deteriorated laryngoscopic view, evaluated by modified Cormack-Lehane grade with a predefined noninferiority margin of 15%. Secondary end points included percentage of glottic opening score, ease of mask ventilation, change in ventilation volume and peak inspiratory pressure during mechanical mask ventilation, ease of tracheal intubation, and resistance encountered while advancing the tube into the glottis. The position of the esophagus was assessed by ultrasound in both groups to determine whether pressure applied to the respective area would be likely to result in esophageal compression. All secondary outcomes were tested for superiority, except percentage of glottic opening score, which was tested for noninferiority. RESULTS: Paratracheal pressure was noninferior to cricoid pressure regarding the incidence of deterioration of modified Cormack-Lehane grade (0% vs 2.9%; absolute risk difference, -2.9%; 95% confidence interval, -9.9 to 2.6, P <.0001). Mask ventilation, measured on an ordinal scale, was found to be easier (ie, more likely to have a lower score) with paratracheal pressure than with cricoid pressure (OR, 0.41; 95% confidence interval, 0.21-0.79; P = .008). The increase in peak inspiratory pressure was significantly less in the paratracheal group than in the cricoid group during mechanical mask ventilation (median [min, max], 0 [-1, 1] vs 0 [-1, 23]; P = .001). The differences in other secondary outcomes were nonsignificant between the groups. The anatomical position of the esophagus was more suitable for compression in the paratracheal region, compared to the cricoid cartilage region. CONCLUSIONS: Paratracheal pressure was noninferior to cricoid pressure with respect to the effect on glottic view during direct laryngoscopy.

A pilot study comparing three bend angles for lighted stylet intubation.

BACKGROUND: For successful lighted stylet intubation, bending the lighted stylet with an appropriate angle is a prerequisite. The purpose of this study was to compare three different bend angles of 70, 80, and 90 degrees for lighted stylet intubation. METHODS: The patient trachea was intubated with a lighted stylet bent at 70, 80, or 90 degrees according to the randomly allocated groups (group I, II, and III, respectively). A lighted stylet combined with a tracheal tube was prepared with a bend angle of 70, 80, or 90 degrees according to the assigned group. We checked the success rate at the first attempt and overall success rate for the two attempts. Additionally, we measured search time, which was time from insertion of the bent union into the patient mouth to the start of advancing the tracheal tube while separating it from the lighted stylet, and evaluated postoperative sore throat (POST) at 2, 4, and 24 h after the recovery from anesthesia. RESULTS: There was no statistically significant difference between group I, II, and III for success rate at first attempt (73.9 %, 88.2 %, and 94.7 %, respectively, p = 0.178), even though there was a trend of increasing success rate with increasing bend angles. For overall success rate, there was similar result to that in the first attempt between the groups I, II, and III (82.6 %, 94.1 %, and 100 %, respectively, p = 0.141). However, search time took significantly longer in group I than groups II and III (p < 0.001). When group II and III were compared for POST with numeric rating scale (0-10), it was significantly lower in group II than III at 2, 4 h after the recovery (0.5 vs. 2.3, p = 0.016, and 0.4 vs. 1.8, p = 0.011, respectively). CONCLUSIONS: The bend angle of the lighted stylet affected the time required for tracheal intubation and POST in our study. 80 and 90 degrees as a bend angle seem to be acceptable for clinicians in regard to success rate of lighted stylet intubation. Considering the success rate of lighted stylet intubation and POST, the bend angle of 80 degrees might be better than 70 and 90 degrees. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT03693235 , registered on 30 September 2018.