The optimum sevoflurane concentration for supraglottic airway device Blockbuster™ insertion with spontaneous breathing in obese patients: a prospective observational study

Predicted effect-site concentrations of remimazolam for i-gel insertion: a prospective randomized controlled study

This study is the first to report 50% and 95% effect-site concentrations (EC50 and EC95, respectively) of the new short-acting benzodiazepine, remimazolam, for the successful insertion of i-gels with co-administration of fentanyl. Thirty patients (38 ± 5 years old, male/female = 4/26) were randomly assigned into five groups to receive one of five different remimazolam doses (0.1, 0.15, 0.2, 0.25, and 0.3 mg/kg bolus followed by infusion of 1, 1.5, 2, 2.5, and 3 mg/kg/h, respectively, for 10 min), which were designed to maintain a constant effect-site concentration of remimazolam at the time of i-gel insertion. At 6 min after the start of remimazolam infusion, all patients received 2 µg/kg fentanyl. i-gel insertion was attempted at 10 min and the success or failure of insertion were assessed by the patient response. Probit analysis was used to estimate the EC50 and EC95 values of remimazolam with 95% confidence intervals (CIs). In the five remimazolam dose groups, two, two, four, five, and six of the six patients in each group had an i-gel successfully inserted. Two patients in the lowest remimazolam dose group were conscious at the time of i-gel insertion and were counted as failures. The EC50 and EC95 values of remimazolam were 0.88 (95% CI, 0.65-1.11) and 1.57 (95% CI, 1.09-2.05) µg/ml, respectively. An effect-site concentration of ≥ 1.57 µg/ml was needed to insert an i-gel using remimazolam anesthesia, even with 2 µg/kg fentanyl. Trial registration: The study was registered in Japan Registry of Clinical Trials on 19 April 2021, Code jRCTs041210009.

A randomised controlled trial to compare blind intubation success through LMA Blockbuster® and I-Gel® LMA

INTRODUCTION

Laryngeal mask airway-blockbuster (LMA-BT) is a relatively new supraglottic airway device (SGAD). In this study, we compared LMA-BT with I-Gel LMA for efficacy of blind tracheal intubation.

MATERIAL AND METHODS

We conducted a single-blind prospective study after ethical approval. One hundred American Society of Anesthesiology (ASA) Grade I-III (age 18-60 years) patients scheduled for elective surgery under general anaesthesia with endotracheal intubation were included and randomly divided into 2 groups. Blind tracheal intubation was performed through LMA-BT ( n = 50) and I-Gel ( n = 50) in groups 1 and 2, respectively. The primary aim was to evaluate the first pass success rate of blind tracheal intubation through the LMAs. The secondary objectives noted were attempts and ease of LMA insertion, total time taken for LMA insertion, airway seal pressure of LMA, ease of NGT insertion through LMA, fibre-optic grading of laryngeal view through LMA, overall success rate and time of intubation through LMA, time for LMA removal, and complications, if any.

RESULTS

In the LMA-BT group, the first pass success rate ( P < 0.019) and the overall success rate of intubation ( P < 0.005) were significantly higher than in the I-Gel group. Using LMA-BT also resulted in statistically significant shorter intubation time ( P < 0.0001) with higher airway seal pressure as compared to I-Gel ( P < 0.001). The difference in the first attempt insertion, number of insertion attempts, ease and time of LMA insertion and removal after intubation, and postoperative complications were comparable among the groups.

CONCLUSIONS

LMA-BT is a superior device as compared to I-Gel LMA as a conduit for blind tracheal intubation.

Comparison of the LMA BlockBuster and intubating LMA as a conduit to blind tracheal intubation

Background and Aims

Primary aim of the study was to evaluate the performance of Intubating LMA (ILMA) and blockbuster LMA in terms of first pass success rate, ease and duration taken for blind tracheal intubation.

Material and Methods

The present prospective randomised study was conducted on 70 patients of either sex aged 18-60 years belonging to ASA physical status I or II. Patients were randomly allocated to either, group I and group B of n = 35 each. In group I and B patients were intubated using ILMA and LMA BlockBuster respectively. Insertion time and ease of placement of supraglottic device, total time taken for successful intubation, number of attempts for endotracheal tube (ETT) placement, and ease of placement of ETT, were recorded.

Results

In both groups, the supraglottic device was placed on the first attempt in 88.6% patients. The first-attempt success rate for ETT placement was 71.4% in group I versus 94.3% in group B, (P = 0.01) with an overall success rate of 88.5% in group I and 100% in group. More failure rate was observed in group I (11.4%) compared to group B (0%). The total time taken for successful intubation in group I was 11.53 ± 6.410 sec and 9.17 ± 2.749 sec in group B (P = 0.04).

Conclusion

We conclude that the modifications in the design of LMA Blockbuster (>95° angle, availability of the parker flex tube 27-30°angle of the emergence of airway tube) make it a more convenient, effective, simpler, and faster intubating device than ILMA.

Randomized Clinical Trial Comparing the Success Rate of Blockbuster Intubating Laryngeal Mask Airway Versus Fastrach Intubating Laryngeal Mask Airway During Blind Endotracheal Intubation

Background A new piece of equipment, the Blockbuster (BB) Intubating Laryngeal Mask Airway (ILMA; Tuoren Medical India, Gurugram, India), was created in 2012. Dr. Chandy created the Fastrach (F) ILMA in 1997, which is another supraglottic airway equipment. The primary purpose of this study was to compare the success rate of intubation with BB-ILMA and F-ILMA. Methods In the chosen age category of >20 to <70 years, undergoing general anesthesia for intubation with ILMAs, 55 patients were in the BB-ILMA (group B), and 55 patients were in the F-ILMA (group F). These ILMAs were put in after the induction and checked to see if adequate ventilation was accomplished with either of these devices. Once ventilation had been attained, we proceeded with fiberoptic scope to visualize the glottis, followed by blind intubation. The primary objective was to compare the first pass successful intubation of BB-ILMA and F-ILMA. The secondary objectives were ease of LMA insertion, time taken for intubation, hemodynamic changes, glottis fiberoptic view, and complications. Results The first pass successful intubation of the BB-ILMA and F-ILMA are 94.5% and 87.3%, respectively, whereas the time taken for intubation in BB-ILMA and F-ILMA are 25.02 seconds (s) and 42.77 s with a p-value of 0.0001, indicating a statistically significant relationship. Conclusion When compared to the F-ILMA (group F), the BB-ILMA (group B) has a higher success rate for blind tracheal intubation, with lesser time taken for intubation and fewer complications.

Long-term high-risk drinking does not change effective doses of propofol for successful insertion of gastroscope in Chinese male patients

Background

Available literature indicates that long-term drinkers demand a higher dose of propofol for induction of anesthesia than non-drinkers. However, there is no study having assessed the influence of long-term high-risk drinking (LTHRD) on the effective doses of propofol for successful insertion of gastroscope with sedation. This study was designed to compare the effective doses of propofol for successful insertion of gastroscope between LTHRD and non-drinking (ND) Chinese male patients.

Methods

Thirty-one LTHRD patients and 29 ND male patients undergoing elective gastroscopy with propofol sedation were enrolled. The modified Dixon’s up-and-down method was applied to determine the calculated median effective dose (ED₅₀) of propofol for successful insertion of gastroscope. Furthermore, the isotonic regression analysis was used to establish the dose–response curve of propofol and assess the effective doses of propofol where 50% (ED₅₀) and 95% (ED₉₅) of gastroscope insertions were successful.

Results

The calculated ED₅₀ of propofol for successful insertion of gastroscope was 1.55 ± 0.10 mg/kg and 1.44 ± 0.11 mg/kg in the LTHRD and ND patients. The isotonic regression analysis further showed that ED₅₀ and ED₉₅ of propofol for successful insertion of gastroscope was 1.50 mg/kg (95%CI, 1.40–1.63) and 1.80 mg/kg (95%CI, 1.74–1.90) in the LTHRD patients, respectively; 1.40 mg/kg (95% CI, 1.27–1.57) and 1.60 mg/kg (95%CI, 1.56–1.65) in the ND patients. The ED₅₀ of propofol for successful insertion of gastroscope was not significantly different between LTHRD and ND patients.

Conclusions

This study demonstrates that the difference in the estimated ED₅₀ of propofol for successful insertion of gastroscope between LTHRD and ND Chinese male patients was not statistically significant.

Trial registration

The study was registered on November 28, 2020 (ChiCTR2000040382) in the Chinese Clinical Trial Registry.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01725-2.

Anesthesia and airway managements for emergency removal of esophageal foreign body in a trisomy 21 patient with mental retardation and predicted difficult airway: A case report

INTRODUCTION

The typical manifestations of patients with a trisomy 21 syndrome are mental retardation and anatomical deformities of face and neck. In the available literature, all case reports regarding anesthetic management of mentally retarded patients have focused on elective surgeries. There is no report regarding anesthetic management of mentally retarded patients undergoing emergency surgery.

PATIENT CONCERNS

A 47-year-old woman with a mental retardation grade 2 by trisomy 21 syndrome suffered from an esophageal foreign body for 3 days and needed emergency removal of esophageal foreign body. The patient had a poor cooperation and obvious anatomical abnormalities of head and neck.

DIAGNOSES

Difficult anesthesia and airway managements for emergency removal of esophageal foreign bodies in a trisomy 21patients with mental retardation and predicted difficult airways.

INTERVENTIONS

Combined use of an intubating supraglottic airway and the flexible bronchoscope-guided intubation after intravenous anesthesia induction.

OUTCOMES

Effective airway was safely established and an esophageal foreign body was successfully removed by rigid esophagoscopy under anesthesia. The patient recovered smoothly without any complication.

LESSONS SUBSECTIONS AS PER STYLE

When general anesthesia and emergency airway management are required in the patients with mental retardation and predicted difficult airways, a combination of the supraglottic airway and the flexible bronchoscope maybe a safe and useful choice for airway control.

Volatile Anesthetics Activate a Leak Sodium Conductance in Retrotrapezoid Nucleus Neurons to Maintain Breathing during Anesthesia in Mice

BACKGROUND

Volatile anesthetics moderately depress respiratory function at clinically relevant concentrations. Phox2b-expressing chemosensitive neurons in the retrotrapezoid nucleus, a respiratory control center, are activated by isoflurane, but the underlying mechanisms remain unclear. The hypothesis of this study was that the sodium leak channel contributes to the volatile anesthetics-induced modulation of retrotrapezoid nucleus neurons and to respiratory output.

METHODS

The contribution of sodium leak channels to isoflurane-, sevoflurane-, and propofol-evoked activity of Phox2b-expressing retrotrapezoid nucleus neurons and respiratory output were evaluated in wild-type and genetically modified mice lacking sodium leak channels (both sexes). Patch-clamp recordings were performed in acute brain slices. Whole-body plethysmography was used to measure the respiratory activity.

RESULTS

Isoflurane at 0.42 to 0.50 mM (~1.5 minimum alveolar concentration) increased the sodium leak channel-mediated holding currents and conductance from -75.0 ± 12.9 to -130.1 ± 34.9 pA (mean ± SD, P = 0.002, n = 6) and 1.8 ± 0.5 to 3.6 ± 1.0 nS (P = 0.001, n = 6), respectively. At these concentrations, isoflurane increased activity of Phox2b-expressing retrotrapezoid nucleus neurons from 1.1 ± 0.2 to 2.8 ± 0.2 Hz (P < 0.001, n = 5), which was eliminated by bath application of gadolinium or genetic silencing of sodium leak channel. Genetic silencing of sodium leak channel in the retrotrapezoid nucleus resulted in a diminished ventilatory response to carbon dioxide in mice under control conditions and during isoflurane anesthesia. Sevoflurane produced an effect comparable to that of isoflurane, whereas propofol did not activate sodium leak channel-mediated holding conductance.

CONCLUSIONS

Isoflurane and sevoflurane increase neuronal excitability of chemosensitive retrotrapezoid nucleus neurons partly by enhancing sodium leak channel conductance. Sodium leak channel expression in the retrotrapezoid nucleus is required for the ventilatory response to carbon dioxide during anesthesia by isoflurane and sevoflurane, thus identifying sodium leak channel as a requisite determinant of respiratory output during anesthesia of volatile anesthetics.

EDITOR’S PERSPECTIVE

Comparison of success rate of BlockBuster® versus Fastrach® LMA as conduit for blind endotracheal intubation: A prospective randomised trial

Background and Aims:

BlockBuster^® Laryngeal Mask Airway, a newer supraglottic airway device, is claimed to be an efficient conduit for endotracheal intubation. Intubating laryngeal mask airway (LMA) is an established device for the same. This randomised study was undertaken to evaluate the success rate of blind intubation using either of these LMAs.

Methods:

Sixty patients of age group 20-60 years undergoing general anaesthesia were randomised in 2 groups, of 30 patients each, for tracheal intubation using either BlockBuster^® LMA (Group B) or the Intubating LMA Fastrach^® (Group F). After induction of anaesthesia, LMAs were inserted and on achieving adequate ventilation with the device, fibreoptic scopy was performed to assess the glottis visualisation score. Blind intubation was attempted through the supraglottic airway devices (SAD). The primary objective was first pass successful intubation and secondary outcomes were ease, time for LMA insertion, oropharyngeal seal pressure (OSP), LMA removal time, fibreoptic scoring and complications. Data was analysed using SPSS V22 software.

Results:

The first-attempt success rate of tracheal intubation was 90% in Group B and 66.6% in Group F (P = 0.028), while the overall success rate of intubation was 96.6% in Group B and 89.9% in Group F (P = 0.3). The OSP in Group B was 33.7 ± 1.8 and 22.7 ± 1.5 cm H₂O in Group F (P = 0.001). Complications such as sore throat and blood stain were reduced with BlockBuster^® LMA.

Conclusion:

BlockBuster^® LMA provides higher first pass success rate of blind tracheal intubation with less complications like sore throat and blood staining.

A feasibility study of jaw thrust as an indicator assessing adequate depth of anesthesia for insertion of supraglottic airway device in morbidly obese patients

Background:

Jaw thrust has been proven as a useful test determining adequate depth of anesthesia for successful insertion of supraglottic airway device (SAD) in normal adults and children receiving intra-venous or inhalational anesthesia induction. This prospective observational study aimed to determine the feasibility and validity of this test when using as an indicator assessing adequate depth of anesthesia for successful insertion of SAD in spontaneously breathing morbidly obese patients receiving sevoflurane inhalational induction.

Methods:

Thirty morbidly obese patients with a body mass index 40 to 73 kg/m² undergoing bariatric surgery in Beijing Friendship Hospital from October 2018 to January 2019 were included in this study. After adequate pre-oxygenation, 5% sevoflurane was inhaled and inhalational concentration of sevoflurane was increased by 1% every 2 min. After motor responses to jaw thrust disappeared, a SAD was inserted and insertion conditions were graded. The anatomic position of SAD was assessed using a fiberoptic bronchoscope.

Results:

The SAD was successfully inserted at the first attempt in all patients. Insertion conditions of SAD were excellent in nine patients (30%) and good in 21 patients (70%), respectively. The fiberoptic views of SAD position were adequate in 28 patients (93%).

Conclusions:

Jaw thrust test is a reliable indicator determining adequate anesthesia depth of sevoflurane inhalational induction for successful insertion of SAD in spontaneously breathing morbidly obese patients.

Clinical trial registration:

ChiCTR1800016868; http://www.chictr.org.cn/showproj.aspx?proj=28646.

Supraglottic jet oxygenation and ventilation for obese patients under intravenous anesthesia during hysteroscopy: a randomized controlled clinical trial

Background

Supraglottic jet oxygenation and ventilation (SJOV) can effectively maintain adequate oxygenation in patients with respiratory depression, even in apnea patients. However, there have been no randomized controlled clinical trials of SJOV in obese patients. This study investigated the efficacy and safety of SJOV using WEI Nasal Jet tube (WNJ) for obese patients who underwent hysteroscopy under intravenous anesthesia without endotracheal intubation.

Methods

A single-center, prospective, randomized controlled study was conducted. The obese patients receiving hysteroscopy under intravenous anesthesia were randomly divided into three groups: Control group maintaining oxygen supply via face masks (100% oxygen, flow at 6 L/min), the WNJ Oxygen Group with WNJ (100% oxygen, flow: 6 L/min) and the WNJ SJOV Group with SJOV via WNJ [Jet ventilator working parameters:100% oxygen supply, driving pressure (DP) 0.1 MPa, respiratory rate; (RR): 15 bpm, I/E; ratio 1:1.5]. SpO₂, P_ETCO₂, BP, HR, ECG and BIS were continuously monitored during anesthesia. Two-Diameter Method was deployed to measure cross sectional area of the gastric antrum (CSA-GA) by ultrasound before and after SJOV in the WNJ SJOV Group. Episodes of SpO₂ less than 95%, P_ETCO₂ less than 10 mmHg, depth of WNJ placement and measured CSA-GA before and after jet ventilation in the WNJ SJOV Group during the operation were recorded. The other adverse events were collected as well.

Results

A total of 102 patients were enrolled, with two patients excluded. Demographic characteristics were similar among the three groups. Compared with the Control Group, the incidence of P_ETCO₂ < 10 mmHg, SpO₂ < 95% in the WNJ SJOV group dropped from 36 to 9% (P = 0.009),from 33 to 6% (P = 0.006) respectively,and the application rate of jaw-lift decreased from 33 to 3% (P = 0.001), and the total percentage of adverse events decreased from 36 to 12% (P = 0.004). Compared with the WNJ Oxygen Group, the use of SJOV via WNJ significantly decreased episodes of SpO₂ < 95% from 27 to 6% (P = 0.023), P_ETCO₂ < 10 mmHg from 33 to 9% (P = 0.017), respectively. Depth of WNJ placement was about 12.34 cm in WNJ SJOV Group. There was no significantly difference of CSA-GA before and after SJOV in the WNJ SJOV Group (P = 0.234). There were no obvious cases of nasal bleeding in all the three groups.

Conclusions

SJOV can effectively and safely maintain adequate oxygenation in obese patients under intravenous anesthesia without intubation during hysteroscopy. This efficient oxygenation may be mainly attributed to supplies of high concentration oxygenation to the supraglottic area, and the high pressure jet pulse providing effective ventilation. Although the nasal airway tube supporting collapsed airway by WNJ also plays a role. SJOV doesn’t seem to increase gastric distension and the risk of aspiration. SJOV can improve the safety of surgery by reducing the incidence of the intraoperative involuntary limbs swing, hip twist and cough.

Trial registration

Chinese Clinical Trial Registry. Registration number, ChiCTR1800017028, registered on July 9, 2018.

Dexmedetomidine reduces sevoflurane EC50 for supraglottic airway device insertion in spontaneously breathing morbidly obese patients

Purpose: This study aimed to assess the effect of intravenous dexmedetomidine (DEX) on sevoflurane EC₅₀ for supraglottic airway device (SAD) insertion in spontaneously breathing morbidly obese patients.

Patients and methods: Thirty-eight morbidly obese patients with a body mass index 40–57 kg/m² who were scheduled for bariatric surgery under general anesthesia requiring tracheal intubation were randomly allocated to two groups receiving the different treatments: group S, saline was given intravenously, and group D, a bolus dose of DEX 1 μg/kg was administered intravenously over 10 mins, followed by intravenous DEX infusion at a rate of 0.5 μg/kg/h. Five percent sevoflurane was initially inhaled for anesthesia induction and then end-tidal expiratory sevoflurane concentration (ET_sev) was adjusted to a target value as to the modified Dixon’s up-and-down method. Patients’ response to SAD insertion was classified as “movement” or “no movement”. The average of the midpoints of all crossover points was defined as calculated sevoflurane EC₅₀ for successful SAD insertion. Furthermore, the probit regression analysis was used to determine sevoflurane end-tidal concentrations where 50% (EC₅₀) and 95% (EC₉₅) insertions of SAD were successful. After the observation was completed, flexible bronchoscope-guided intubation was performed through the SAD.

Results: The calculated sevoflurane EC₅₀ for successful SAD insertion was significantly lower in group D than in group S (1.75±0.32% vs 2.92±0.26%, p<0.001). By the probit regression analysis, EC₅₀ and EC₉₅ of sevoflurane for successful SAD insertion were 1.59% (95% CI, 1.22–1.90%) and 2.15% (95% CI, 1.86–3.84%) in group D, respectively, and 2.81% (95% CI, 2.35–3.29%) and 3.32% (3.02–6.74%) in group S.

Conclusion: When sevoflurane inhalational induction is performed in spontaneous breathing morbidly obese patients, intravenous DEX can reduce sevoflurane EC₅₀ for successful SAD insertion by about 40%.

Chinese Clinical Trial Registry: No. ChiCTR1800016868