Usefulness of an automatic cuff pressure controller (SmartCuff) in inhibiting gasleakage around the cuff after tracheal intubation: a randomized controlled study.

PURPOSE: Gas leakage around the cuff of a tracheal tube may frequently occur after tracheal intubation and inflation of the cuff. We assessed if the SmartCuff (Smiths Medical Japan, Tokyo, Japan), an automatic cuff pressure controller, would effectively prevent gas leakage. METHODS: Seventy adult patients were allocated randomly to one of two groups. After induction of general anesthesia and tracheal intubation, in one group (Syringe group), a syringe was used to inflate the cuff, until there was no audible gas leakage, at the airway pressure at 20 cmH2O. In the other group (SmartCuff group), the SmartCuff was used to maintain the cuff pressure to be 20 cmH2O. The mechanical ventilation (tidal volume of 8 ml.kg-1 and 12 breaths per min) was started. The incidence and percentage of gas leakage, and the proportion of adequate seal (defined as gas leakage of < 10%) between the groups were compared. RESULTS: The incidence of audible gas leakage was significantly higher in the Syringe group (10 of 35 patients (28%)) than in the SmartCuff group (none of 35 patients (0%)) (P = 0.00046, 95%CI for difference: 15-43%), and the proportion of adequate seal was significantly lower in the Syringe group (19 of 35 patients (54%)) than in the Smart cuff group (33 of 35 patients (94%)) (P = 0.0001, 95% CI for difference: 20-58%). CONCLUSION: Gas leakage may frequently occur after tracheal intubation, and the use of the SmartCuff can effectively maintain the sealing effect of the cuff.

Efficacy of a surgical mask during high-flow nasal oxygen therapy in preventing aerosol dispersion: a randomized controlled study.

PURPOSE: It is not clear whether or not high-flow nasal oxygenation used in patients with severe respiratory tract infection, or coughing, increases the risk of infection to the healthcare personnel, and whether or not applying a surgical mask to the patient's face or treating the patient in a negative-pressure room can reduce the risk. METHODS: In a randomized crossover design, we compared in 50 participants receiving high-flow nasal oxygenation, the aerosol counts measured at approximately 20 cm above the participant's mouth in 32 different circumstances (with or without coughing, with or without wearing a surgical mask, at four different flow rates of oxygenation, in a positive- or negative-pressure operating room). RESULTS: In a positive-pressure room, a surgical mask significantly decreased the aerosol counts during coughing (P = 0.0005), or during no coughing (P = 0.009), under high-flow nasal oxygenation (at 60 l.min-1). In the negative-pressure room, the aerosol count was significantly lower than in the positive-pressure room, for all the circumstances (all P < 0.001), and a surgical mask significantly decreased the aerosol counts during coughing (P = 0.047) but not during no coughing (P = 0.60). CONCLUSION: In conclusion, treating a patient in a negative-pressure room, or applying a surgical mask, during high-flow nasal oxygenation (with the flow rate of 60 l.min-1) would inhibit, but would not completely prevent, dispersion of aerosols by coughing.

Remimazolam: a randomized controlled study of its suitability for insertion of a supraglottic airway.

PURPOSE: Loss of motor response to thrusting the jaw forward is a useful indicator for uncomplicated insertion of a supraglottic airway. The aim of this study was to assess the suitability of remimazolam for insertion of a supraglottic airway assessed by loss of response to jaw thrusting. METHODS: Seventy patients, who were scheduled for elective surgeries under general anesthesia, were allocated randomly to one of two groups. In one group (remimazolam group), remimazolam was infused 12 mg kg-1 h-1 (50 mg maximum), and in the other (propofol group), propofol was infused at 120 mg kg-1 h-1 (500 mg maximum). Once the eyelash reflex disappeared, response to jaw thrusting was assessed. Primary outcome measure was the proportion of patients with loss of response to jaw thrusting before reaching the maximum dose of the test drug. We planned an interim analysis (of one time) after 40 patients, using the Pocock adjustment method. RESULTS: From the interim analysis results, the study was stopped after recruitment of 40 patients. Loss of response to jaw thrusting was observed in all of 21 patients (100%) in the propofol group, and in 9 of 19 patients (47%) in the remimazolam group. There was a significant difference in the proportion between the groups (P = 0.0001, 95% CI for difference 30-75%). CONCLUSION: Remimazolam frequently does not inhibit response to jaw thrusting, and thus remimazolam is not a suitable induction agent for uncomplicated insertion of a supraglottic airway unless either a neuromuscular blocking agent or an opioid is co-administered.

Efficacy of McGRATH®MAC videolaryngoscope blade 1 for tracheal intubation in small children: a randomized controlled clinical study.

BACKGROUND: Videolaryngoscopes may not be as effective in small children as they are in older children and in adults. The size 1 blade is commercially available for the McGRATH®MAC videolaryngoscope (Covidien, Medtronic, Tokyo, Japan), but its efficacy in comparison with a Macintosh laryngoscope blade 1 is not known. AIM: The main aim of this study was to assess the efficacy of McGrath®MAC blade 1 in comparison with a conventional Macintosh laryngoscope blade 1, in children aged less than 24 months. METHODS: Thirty-eight children aged less than 24 months were randomly allocated to one of two groups, and tracheal intubation was attempted using either a direct laryngoscope with a Macintosh blade 1 or a videolaryngoscope with a McGRATH®MAC blade 1. In another 12 children aged 2-4 years, the same comparisons were made with blade 2. The primary outcome measure was time to tracheal intubation using a size 1 blade. RESULTS: Tracheal intubation took significantly longer with a McGRATH®MAC blade 1 (median (interquartile range): 38.0 (31.8-43.5) s) than with the Macintosh blade 1(27.4 (25.9-29.2) s) (p < 0.0001; median difference (95% CI for the median difference): 10.6 (6.4-14.0) s), mainly due to difficulty in advancing a tube into the trachea. No significant difference was observed for the size 2. CONCLUSIONS: In small children without predicted difficult airways, time to intubate the trachea was significantly longer for a McGRATH®MAC blade 1 than a Macintosh blade 1. CLINICAL TRIAL REGISTRATION: jRCT1032220366.

A fragmented segment of a central venous catheter caused delayed ventricular fibrillation: a case report.

BACKGROUND: Central venous port systems may be safely used for chemotherapy of patients with cancer, but several complications may occur associated with their use. CASE PRESENTATION: An 83-year-old man with heat stroke was transferred to our emergency department, where he was treated and became able to eat on the same day. He had been fit and healthy, except for colorectomy and chemotherapy using a central venous access port placed in the right upper jugular vein 8 years ago. The next day, he suddenly had ventricular fibrillation. Cardiopulmonary resuscitation was successful. Emergency coronary angiography showed a catheter-like foreign body in the coronary sinus. Physicians failed to remove the foreign body using catheter therapy, and ventricular fibrillation occurred repeatedly. After induction of general anesthesia, the fractured catheter was removed surgically. Postoperative course was uneventful. CONCLUSIONS: A fragmented segment of a catheter may suddenly cause ventricular fibrillation years later.

Efficacy of an aid (gastric tube insertion guide) for oral insertion of a gastric tube: a randomized controlled trial.

PURPOSE: Insertion of a gastric tube orally may be more difficult than its insertion nasally, and thus, any aid to facilitate its insertion may be useful. Gastric tube insertion guide (Fuji Medical Corporation, Tokyo, Japan) has recently become commercially available. We felt that this device might be useful in facilitating oral insertion of a gastric tube, but there has been no formal study assessing its efficacy. The main aim of this study was to assess whether or not this "tube guide" would facilitate insertion of an orogastric tube. METHODS: As a randomized controlled clinical study, we planned to study 40 patients, to assess the hypothesis that the success rate of insertion of an orogastric tube would be higher with the use of the "tube guide" than without. Patients were recruited when they were 20 years old, or older, and allocated randomly to one of two groups (20 people each group). In one group, the conventional "blind" insertion method was used and in the other group the "tube guide" insertion method. RESULTS: The success rate was significantly higher for the "tube guide" method than the "blind" insertion method (P = 0.0012, 95% CI for difference: 23-67%). CONCLUSION: We have shown that the use of the gastric tube insertion guide® facilitates insertion of an orogastric tube.

Efficacy of a gastric tube insertion guide for insertion of a nasogastric tube: a prospective, randomized controlled clinical study.

PURPOSE: We studied whether a newly available gastric tube insertion guide (Fuji Medical, Tokyo, Japan) was effective in insertion of a nasogastric tube. METHODS: Sixty anesthetized patients were randomly allocated to three groups, and we attempted to insert a nasogastric tube with a blind technique (Group B), with the lateral neck pressure (Group L), or with the tube guide (Group G). If the insertion failed in Group B or L, its insertion was attempted with the tube guide. Primary outcome measure was the insertion success rate within 300 s. RESULTS: The success rate in Group G (19 of 20 patients) was significantly higher than Group L (13 of 20 patients) (P = 0.04; 95% confidence intervals for difference: 16-44%), and than Group B (11 of 19 patients) (P = 0.008; 23-50%). In the 15 patients of Groups B and L, in whom insertion had failed, insertion with the tube guide was successful in 14 patients. There was no significant difference in insertion time between the groups, but in patients in whom insertion was successful, it was significantly longer in Group G (median of 147 s) than in Group L (66 s) (P < 0.01) and Group B (46 s) (P < 0.01). Minor complications occurred in 2 patients in Group B, 1 in Group L, and 5 in Group G (P > 0.05). CONCLUSION: We conclude that the gastric tube insertion guide (Fuji Medical, Tokyo, Japan) may be useful when the conventional method of insertion has failed.

Efficacy of an aerosol suction device Free-100 M in removing aerosols produced by coughing to minimize COVID-19 infection.

PURPOSE: The healthcare workers are at the greatest risk of being exposed to viral infection during airway management of a patient with coronavirus disease 2019 (COVID-19). An air extractor which suctions air around the patient's face would reduce the spread of viral aerosols during coughing, but no study has confirmed this. We assessed whether or not an air extractor reduces the amount of aerosols spreading toward the operator's face, during coughing of simulated patients. METHODS: After obtained approval of the study by a research ethics committee and written informed consent from 20 volunteers (and additional 20 volunteers), we asked each volunteer to lie supine on a table in a positive-pressure management operating room. As a cross-over design, we used an airborne particle counter (Handheld 3016, SGY company, Tokyo) to measure the aerosols approximately 30 cm above the participant's mouth, while the volunteer was coughing, with and without the use of an air extractor Free-100 M (Forest-one, Funabashi), facing the participant's mouth. In another 20 volunteers, the aerosols were measured, while each volunteer was lying supine, without coughing, and without the use of the air extractor. RESULTS: The aerosol count during coughing was significantly lower when the air extractor was used [median: 55 (interquartile range: 15-128)] than when it was not used [73 (44-201)] [p = 0.001, difference: 19 (95%CI: 4-70)]. CONCLUSIONS: The Free-100 M air extractor would reduce, but do not remove all, aerosols produced by coughing of a patient, and thus may reduce the risk of infection of COVID-19.

Tracheal tube cuff pressure during anesthesia for robotic-assisted laparoscopic prostatectomy and the efficacy of an automatic cuff pressure controller (SmartCuff): observational studies of 1-sample paired data.

PURPOSE: The cuff pressure of a tracheal tube may increase during robot-assisted laparoscopic surgery for prostatectomy (RALP), which requires pneumoperitoneum in a steep head-down position, but there have been no studies which confirmed this. METHODS: In study 1, we studied how frequently the cuff pressure significantly increased during anesthesia for the RALP. In study 2, we studied if the SmartCuff (Smiths Medical Japan, Tokyo) automatic cuff pressure controller would minimize the changes in the intracuff pressure. With approval of the study by the research ethics committee (approved number: 20115), we measured the cuff pressures in anesthetized patients undergoing RALP and in those undergoing gynecological laparotomy (as a reference cohort), with and without the use of the SmartCuff. RESULTS: In 21 patients undergoing RALP, a clinically meaningful increase (5 cmH2O or greater) was observed in all the 21 patients (P = 0.00; 95% CI for difference: 86-100%), whereas in 23 patients undergoing gynecological laparotomy, a clinically meaningful decrease (5 cmH2O or greater) was observed in 21 of 23 patients (91%, P < 0.0001; 95% CI for difference: 72-99%). With the use of the SmartCuff, there was no significant increase in the incidence of a clinically meaningful change in the intracuff pressure in either cohort. CONCLUSION: The cuff pressure of a tracheal tube would frequently increase markedly in patients undergoing RALP, whereas it would frequently decrease markedly in patients undergoing gynecological laparotomy. The SmartCuff may inhibit the changes in the cuff pressure during anesthesia.

Standard of anesthesia care: possible dissociation from recommendations made by clinical practice guidelines.

A medical malpractice lawsuit may be brought against health care providers, if there was a possibility of a negligence, or failure to meet the standard of care. Recently, clinical practice guidelines have increasingly been used as evidence of the standard of care. Nevertheless, it is not clear whether these guidelines can be used as evidence of the standard of care. We carried out a snapshot study to know whether or not there were dissociations between the current standard of anesthesia care and recommendations made by clinical practice guidelines. We asked all the 80 heads of Anesthesiology departments of Japanese public and private Universities, to answer questions related to difficult airway management after induction of anesthesia, postoperative monitoring of breathing, and of the presence or the absence of neuropathy of the lower legs after regional anesthesia. The response rate was 71% (57/80). The majority of anesthesiologists had little experience with front-of-neck access in patient, and responders might frequently make repeated attempts at tracheal intubation. Postoperative monitoring was frequently not routinely performed. In conclusion, this study has shown that there may be various degrees of dissociations between the current standard of anesthesia care and the recommendations made by clinical practice guidelines that had been used as evidence of the standard of care in medical malpractice lawsuit cases in Japan.

Margin of safety for needle puncture of a radial artery.

The radial artery is the preferred site for arterial cannulation because of consistent anatomic accessibility, ease of cannulation, and a low incidence of complications. One possible risk associated with cannulation is an injury to the superficial branch of the radial nerve. The radial nerve divides to the superficial branch and the deep branch at the top of the forearm, and the superficial branch lies behind the brachioradialis muscle close to the lateral side of the radial artery and terminates the lateral side of the radial artery about 7 cm proximal to the wrist. The segment where the superficial branch of the radial nerve runs side-by-side the radial artery ("run side-by-side segment) is an increased risk area of nerve injury. We studied 100 volunteers to measure a "safe" segment (the length between the styloid process and the distal edge of the "run side-by-side segment), using an ultrasonograph. The 95%reference interval (which indicates the central 95% of a reference population) of the "safe" segment was 6.8-11.6 cm [with the mean 9.4 (standard variation: 1.7)] in men, and 5.4-11.0 [8.2 (1.4)] cm in women. In conclusion, we have shown that the margin of safety for needle puncture of a radial artery is about 6.8 cm from the wrist for in men, and 5.4 cm from the wrist for in women.

Rocuronium Bromide Intravenous Solution Maruishi® is more suitable than ESLAX Intravenous® during rapid-sequence induction of anesthesia.

PURPOSE: Rocuronium Bromide Intravenous Solution® (Maruishi Pharmaceutical Co., Ltd, Osaka, Japan) is a newly developed generic drug and we have noticed that compared with conventional rocuronium formulations [e.g. Esmeron (Eslax), MSD Co. Ltd., Tokyo, Japan], rocuronium Maruishi appeared to cause less pain or withdrawal movement. The aim of this study was to assess the hypothesis that the injection of rocuronium Maruishi causes less body movement than rocuronium MSD does, during rapid-sequence induction of anesthesia. METHODS: Sixty patients were allocated randomly to one of two groups. In one group, rocuronium MSD was used and in the other group, rocuronium Maruishi was used. After induction of general anesthesia, a test drug (containing rocuronium) 0.9 mg/kg was injected. Patient's withdrawal movement was graded with the scale. Primary outcome measure was the incidence of moderate or severe movement after the injection of rocuronium. Secondary outcome measure was the degree of movement between the groups. RESULTS: Moderate or severe withdrawal movement was observed after the injection of rocuronium MSD in 11 of 30 patients (37%) and after the injection of rocuronium Maruishi in 3 of 30 patients (10%). There was a significant difference in the incidence between the groups (P = 0.013, 95% CI for difference 26-28%). The degree of movement was also significantly greater for rocuronium MSD than for rocuronium Maruishi (P = 0.015). CONCLUSION: Compared with rocuronium MSD, rocuronium Maruishi is more suitable than conventional rocuronium formulations, for rapid-sequence induction of anesthesia.

Visualization of injectate spread of intercostal nerve block: a cadaveric study.

INTRODUCTION: Intercostal nerve block and neurolysis are widely used procedures, but their injectate spread has not been well understood. Previous studies have reported unexpected outcomes (paravertebral or epidural anesthesia) and spinal cord injury after intercostal nerve block and neurolysis. To investigate a possible mechanism for these complications, we aimed to visualize the flow of liquid injected near the intercostal nerve, using cadavers. METHODS: We performed a simulated intercostal nerve block study using two Thiel-embalmed cadavers. Dye was injected into the interfascial plane between the internal and innermost intercostal muscles under ultrasound guidance (blue, 10 ml) or under direct vision (green, 5 ml). RESULTS: Dye leakage began with injection of only 0.5-2 ml and occurred between the innermost intercostal muscle fibers. The dye injected around the intercostal nerve penetrated into the extrapleural space and reached the paravertebral space. CONCLUSIONS: Injectate placed around the intercostal nerve easily penetrate the extrapleural space and reach the paravertebral space. Intercostal nerve block or neurolysis has a risk of impairing at least the sympathetic chain and conceivably affecting the central nervous system.