Ryusuke Ueki

Validation of the Pentax-AWS Airwayscope utility as an intubation device during cardiopulmonary resuscitation on the ground

PurposeThe 2005 American Heart Association guidelines for cardiopulmonary resuscitation emphasize that all rescuers should minimize interruption of chest compressions even for endotracheal intubation. We previously reported that the utility of the Pentax-AWS Airwayscope (AWS) was superior to that of the Macintosh laryngoscope (McL) for securing airways during chest compression in “on the bed” simulated circumstances. However, because most cardiopulmonary arrest happens “on the ground” in the real world, we compared the utility of the McL and the AWS during chest compression on the ground and on the bed.MethodsFourteen doctors training in the anesthesia department performed tracheal intubation on a manikin with the McL and the AWS in simulations “on the bed” and “on the ground”.ResultsIn the McL trial, 6 participants failed on the bed, and 10 of them also failed on the ground during chest compression. In the AWS trial, all participants successfully secured the airway regardless of chest compression both on the bed and on the ground. With the AWS, intubation time was not lengthened because of chest compression either on the bed or on the ground. The AWS scored better than the McL on the visual analog scale in laryngoscopy and tube passage of the glottis both on the bed and on the ground.ConclusionWe conclude that the AWS is an effective device for endotracheal intubation during chest compression not only on the bed but also on the ground.

Comparison of optic laryngoscope Airtraq ® and Miller laryngoscope for tracheal intubation during infant cardiopulmonary resuscitation

BACKGROUND Recent resuscitation guidelines for infant cardiopulmonary resuscitation (CPR) emphasize that all rescuers should minimize interruption of chest compressions, even for endotracheal intubation. We compared the utility of the Miller laryngoscope (Mil) with Airtraq (ATQ) during chest compression in an infant manikin. METHODS Twenty staff doctors in intensive care and emergency medicine performed tracheal intubation on an infant manikin with Mil and ATQ with or without chest compression. RESULTS In Mil trials, no participants failed without chest compression, but 6 of them failed during chest compression (P < 0.05). In ATQ trials, all participants successfully secured the airway regardless of chest compression. Intubation time was significantly lengthened due to chest compression in Mil trials, but not in ATQ trials. The visual analog scale (VAS) for laryngoscope image did not significantly change due to chest compression for ATQ or Mil trials. In contrast, chest compression worsened VAS scores for tube passage through the glottis in Mil trials, but not in ATQ trials. CONCLUSION We conclude that ATQ performed better than Mil for endotracheal intubation during chest compression in infant simulations managed by expert doctors.

Comparison of air-Q® and Soft Seal® laryngeal mask for airway management by novice doctors during infant chest compression: A manikin study

BACKGROUND Recent resuscitation guidelines for infant cardiopulmonary resuscitation (CPR) emphasise that rescuers should minimise the interruption of chest compressions. To that end, supraglottic devices such as laryngeal mask airways (LMAs) are suggested as a backup for airway management during infant CPR. We therefore compared the utility of the air-Q(®) LMA (air-Q) with that of the Soft Seal(®) LMA (Soft Seal) for infant CPR in an infant manikin. METHODS Twenty-four novice doctors in the anaesthesia department performed insertion and ventilation with air-Q and Soft Seal on an infant manikin with or without chest compression. RESULTS Two doctors failed to insert the Soft Seal without chest compression, while nine failed during chest compression (P<0.05). However, only one doctor failed to insert the air-Q without chest compression, and two doctors failed during chest compression. Insertion time was not significantly increased with chest compression using either device. Insertion time during chest compression was significantly shorter for the air-Q than for the Soft Seal (P<0.05). The visual analogue scale (VAS) was used to evaluate difficulty of use (0mm (extremely easy) to 100mm (extremely difficult)). VAS scores did not change significantly by the addition of chest compression with either device; however, VAS scores during chest compression were significantly higher with Soft Seal than with the air-Q device. CONCLUSION We conclude that novice doctors find the air-Q easier to use than Soft Seal for emergency airway management during chest compression in infants, in an infant manikin.

Evaluation of tracheal intubation in several positions by the Pentax-AWS Airway Scope : a manikin study

PurposeIn emergency situations, rescuers must occasionally secure the airway while the patient is in a restricted position rather than in the ideal supine position. We hypothesized that the Pentax-AWS Airway Scope (AWS) may be useful for emergent tracheal intubation in such positions.MethodsThirteen non-anesthesia residents performed tracheal intubation on a simulated manikin in the supine (Supine), left-lateral decubitus (Left-LT), right-lateral decubitus (Right-LT), prone (Prone), and sitting (Sitting) position, respectively, to assess AWS performance.ResultsIntubations were successful in all five positions. The time needed to secure the airway did not differ significantly between the Left-LT and Supine positions. Doctors required significantly more time to secure the airway in the Prone, Sitting, and Right-LT positions than in the Supine position. Visual analog scale (VAS) scoring of the subjective difficulty of laryngoscopy was lower in the Supine position rather than in the Right-LT, Prone, and Sitting positions. The VAS score of subjective difficulty of tracheal tube passage through the glottis was significantly higher in the Sitting position than in the other four positions.ConclusionAlthough tracheal intubations with AWS in all five positions tested were successful, intubation with the patient in the Sitting, Right-LT, and Prone positions was more difficult and required more time than that in the Supine position.

Emulsion of flurbiprofen axetil reduces propofol injection pain due to a decrease in free propofol concentration

PurposeFlurbiprofen axetil emulsion (FA), a prodrug of nonsteroidal anti-inflammatory drugs (NSAIDs) that is widely used for perioperative pain relief in Japan, has been effective for reducing propofol injection pain, but the mechanism is unclear. The purpose of this study was to test the hypothesis that the reduction of propofol injection pain by FA may be attributed to a decrease in free propofol concentration.MethodsDiprivan (propofol emulsion; Dipri; AstraZeneca, Cheshire, UK) and Propofol-Lipuro (Lipuro; B. Braun, Melsungen, Germany) were used. A randomized double-blind study was performed to compare pain on injection with six kinds of propofol solution: plain Dipri, a 3 : 1 (v/v) mixture of Dipri and saline (Dipri-S), a 3 : 1 mixture of Dipri and FA (Dipri-FA), plain Lipuro, a 3 : 1 mixture of Lipuro and saline (Lipuro-S), and a 3 : 1 mixture of Lipuro and FA (Lipuro-FA). Three hundred patients (American Society of Anesthesiologists [ASA] physical status [PS] I–II) scheduled for elective surgery received one of these six propofol emulsions (n = 50, each group). Injection pain was evaluated every 10 s after the start of a 1-min infusion of up to 2 mg·kg−1 propofol. We also measured the in vitro free propofol concentrations of the propofol preparations that we tested (n = 5, each).ResultsThe mixture of FA with propofol decreased the incidence of injection pain, compared with plain propofol, for Lipuro (P < 0.01) but not for Dipri. The free propofol concentration in each emulsion in vitro was also decreased by mixing the propofol with saline or FA. The incidence of pain was reduced in a free-propofol concentration-dependent manner (R2 = 0.926).ConclusionThe findings suggest that the reduction of propofol injection pain by FA may be explained, at least in part, by a reduction in the free propofol concentration.

Comparison of the Miller Laryngoscope and Videolaryngoscope for Tracheal Intubation by Novice Doctors during Neonatal Cardiopulmonary Resuscitation: A Randomized Crossover Simulation Trial

OBJECTIVE Recent guidelines for neonatal cardiopulmonary resuscitation emphasize the importance of adequate ventilation. In cases of failed resuscitation with positive pressure ventilation, tracheal intubation and chest compressions are recommended. The present study compared the utility of the Miller laryngoscope (Mil) and the videolaryngoscope Pentax-AWS Airway Scope (AWS; Hoya, Tokyo, Japan) with an infant or neonatal-sized Intlock (AWS-N; Pentax) during chest compressions on a neonatal manikin. STUDY DESIGN A total of 23 novice doctors performed tracheal intubation on a neonatal manikin using the Mil and AWS-N, with or without chest compressions. RESULTS In the Mil trials, all participants secured the airway without chest compressions, but nine failed with compressions (p < 0.001). In AWS-N trials, all participants succeeded regardless of whether chest compressions were performed or not. Intubation time was significantly longer with chest compressions with the Mil (p < 0.001), but not with the AWS-N. Laryngoscopy difficulty, as assessed by a visual analog scale (VAS), increased significantly with chest compressions with the Mil, but not with the AWS-N, while the VAS for tube passage through the glottis increased with compressions with the Mil, but not with the AWS-N. CONCLUSION The AWS-N is an effective device for endotracheal intubation during chest compressions in neonatal simulations performed by novice doctors.

Significance of debriefing methods in simulation-based sedation training courses for medical safety improvement in Japan

Based on the American Society of Anesthesiologists’ Practice Guidelines for Sedation and Analgesia by Non-Anesthesiologists (ASA-SED), a sedation training course aimed at improving medical safety was developed by the Japanese Association for Medical Simulation in 2011. This study evaluated the effect of debriefing on participants’ perceptions of the essential points of the ASA-SED.A total of 38 novice doctors participated in the sedation training course during the research period. Of these doctors, 18 participated in the debriefing group, and 20 participated in non-debriefing group. Scoring of participants’ guideline perceptions was conducted using an evaluation sheet (nine items, 16 points) created based on the ASA-SED.The debriefing group showed a greater perception of the ASA-SED, as reflected in the significantly higher scores on the evaluation sheet (median, 16 points) than the control group (median, 13 points; p < 0.05). No significant differences were identified before or during sedation, but the difference after sedation was significant (p < 0.05).Debriefing after sedation training courses may contribute to better perception of the ASA-SED, and may lead to enhanced attitudes toward medical safety during sedation and analgesia.

Comparison of placental transfer of local anesthetics in perfusates with different pH values in a human cotyledon model

PurposeWe aimed to investigate the placental transfer of local anesthetics in perfusates with different pH values, using a dual-perfused human cotyledon model.MethodsThe dual-perfused human cotyledon model was prepared from placentas obtained following cesarean delivery (n = 5). Protein-free solution was perfused through both maternal and fetal arteries. Four amide-type local anesthetics (mepivacaine [Mep]; lidocaine [Lid]; bupivacaine [Bup]; and ropivacaine [Rop]) were added to the maternal perfusate at 1 µg·ml−1. Three conditions were tested (stage 1, maternal pH 7.4, fetal pH 7.4; stage 2, maternal pH 7.4, fetal pH 6.9; and stage 3, maternal pH 6.9, fetal pH 6.9). Venous blood samples were collected from the fetal circuit after stabilization. The fetal vein/maternal artery concentration ratio (F/M ratio) of the local anesthetics was used as an index of placental transfer. The concentration of human chorionic gonadotropin (hCG) in the maternal vein was measured at the end of each stage.ResultsThe F/M ratios in all stages were in the order of: Mep > Lid > Bup ≒ Rop. The F/M ratios of Mep were significantly higher than those of the other local anesthetics in all stages. The F/M ratios of Lid were higher than those of Rop in stages 2 and 3. The F/M ratios of Lid and Rop were higher in stage 2 than in stage 3. However, the differences between the F/M ratios in the three stages were not as large as expected from the basic uncharged ([B]) condition and pH gap. The concentration of hCG showed a time-dependent decrease with increasing stage (stage 1, 81.0 ± 58.9 mIU·ml−1; stage 2, 57.4 ± 31.8 mIU·ml−1; stage 3, 32.1 ± 19.7 mIU·ml−1).ConclusionOur data clearly show that it is the basic uncharged concentration that mainly determines the placental transfer of amide-type local anesthetics with protein-free perfusate. This finding suggests that Rop and Bup can be used more safely than Mep in terms of placental transfer.

Blood transfusion-induced anaphylaxis and coronary artery spasm during general anesthesia

Anaphylactic reactions to blood transfusion can lead to life-threatening cardiovascular disruptions. We describe a case in which anaphylaxis due to blood transfusion during general anesthesia was the probable cause of coronary artery spasm. Thirty minutes after the transfusion of concentrated red blood cells, the patient’s blood pressure had dropped to 70/40 mmHg and peak airway pressure had increased to 35 cmH2O. The ST segment of the ECG was simultaneously elevated, and the left upper arm became extensively flushed. The tryptase concentration in the patient’s plasma collected 3 h postoperatively was 13.9 μg·l−1 (normal range, 2.1–9.0 μg·l−1). This case report emphasizes that anaphylactic reactions to blood transfusion can potentially lead to coronary artery spasm.

Difficult airway management using the Pentax-AWS (Airway Scope) for a patient with bilateral giant thyroid tumors

We describe the successful application of the Pentax Airway Scope (AWS) in a sitting patient who presented with severe aortic stenosis (AS) and bilateral giant thyroid tumors. A 67-year-old woman weighing 63 kg complained of dyspnea at rest and repeated loss of consciousness 3 months prior to her visit. She was diagnosed with severe AS and was scheduled for aortic-valve replacement. Her past medical history was remarkable for diabetes-mellitus and untreated sleep apnea. She also encountered radiocontrast nephropathy after cardiac catheterization and thus venovenous hemodialysis was initiated 2 months before aortic-valve replacement surgery. She also had a history of bilateral benign adenomatous giant thyroid tumors (Fig. 1a). The patient was reluctant to undergo resection of these giant tumors. NYHA functional class was Class IV, and she could not maintain a supine position. She required noninvasive positive pressure ventilation at night. SpO2 was 85–88% with oxygen at 3 L/min via nasal cannula. Given that preoperative neck and chest CT revealed airway displacement by these tumors (Fig. 1b), it was speculated that dyspnea was due in part to airway compression by these giant tumors. To assess the glottis and avoid hypertension and tachycardia due to prolonged laryngoscopy, we decided to use the AWS for awake intubation in the sitting position [1]. The patient did not receive preoperative medication. She was preoxygenated (5 L/min nasal cannula) in the sitting position. Percutaneous cardiopulmonary support stood by for salvage in the circumstance of ‘‘cannot ventilate’’. The base of the tongue and the pharyngeal walls were anesthetized with 8% lidocaine spray (total dose 64 mg). Fentanyl (50 lg) and midazolam (1 mg) were intravenously administered. We placed the AWS, observed the glottis and airway, and confirmed that the glottis was not displaced. We also applied 4 mL 4% lidocaine for laryngotracheal topical anesthesia (LTA) under AWS observation. At this point, there was a sudden decrease in SpO2 to 49% arising from depressed spontaneous breathing. Manual support ventilation in the sitting position was initiated and SpO2 recovered. Subsequently, we intubated the patient with a single-lumen tube under AWS guidance confirmed by endtidal CO2 (Fig. 1c). During this period, we did not observe significant hemodynamic abnormalities (i.e., change of systolic blood pressure was within 10 mmHg). Thyroid tumors, especially bilateral giant tumors, are potential causes of difficult airways. Tracheostomy using local anesthetics is sometimes impossible in advanced cases because of anatomical distortions of the anterior neck. Given that our patient could not keep a supine position, we performed tracheal intubation in the sitting position so that sufficient spontaneous breathing could be maintained. Rapid and reliable oral intubation in the sitting position is possible using AWS. Recent studies showed that the mobile camera screen of the AWS enables indirect views of the glottis and intubation in several positions, for example sitting, especially for morbidly obese patient [2]. The AWS also enables maintenance of sufficient spontaneous breathing and N. Komasawa (&) R. Ueki T. Tatara C. Tashiro Department of Anesthesiology, Hyogo College of Medicine, Mukogawa-cho 1-1, Nishinomiya, Hyogo 663-8501, Japan e-mail: nkomazaw@hyo-med.ac.jp