The Pentax-AWS®rigid indirect video laryngoscope: clinical assessment of performance in 320 cases

Efficacy of the Airway Scope on tracheal intubation in the lateral position: comparison with the Macintosh laryngoscope

BACKGROUND

The Airway Scope (AWS) may become a rescue airway device to secure the airway in the lateral position. We evaluated the efficacy of the AWS on tracheal intubation in patients in this position in comparison with the Macintosh laryngoscope.

METHODS

Seventy patients scheduled for surgery in the lateral position under general anaesthesia with tracheal intubation were randomised into two groups: intubation with the Macintosh laryngoscope and that with the AWS. After general anaesthesia and muscle relaxation, experienced anaesthetists performed laryngoscopy and intubation using either laryngoscope in the right or left lateral position. Laryngoscopic view, intubation time, intubation difficulty scale score and success rate of tracheal intubation (within 60 s) were recorded and compared between intubation with the Macintosh laryngoscope and that with the AWS.

RESULTS

In the lateral position, the laryngoscopic view with the AWS was significantly better than that with the Macintosh laryngoscope (P < 0.01). Tracheal intubation was successful at the first attempt with the AWS in all patients and with the Macintosh laryngoscope in 85.3% of patients (P < 0.05). The median times to intubation with the AWS and with the Macintosh laryngoscope were 14 (interquartile range, 9-19) s and 29 (20-31) s, respectively (P < 0.01). Also, the AWS significantly reduced the intubation difficulty scale score compared with the Macintosh laryngoscope (P < 0.01).

CONCLUSION

In the situation in which securing the airway in the lateral position is required, the AWS is more effective than the Macintosh laryngoscope.

Airway scope for tracheal intubation in the lateral position

BACKGROUND

Tracheal intubation in the lateral position is difficult because the laryngeal view is compromised during direct laryngoscopy. The Airway Scope facilitates intubation even when laryngeal views are poor with direct laryngoscopy, as they often are in the lateral position. We thus compared the efficacy of the Airway Scope in supine patients with those in the left- and right-lateral positions.

METHODS

Anesthetized adults were randomly assigned to supine, left-lateral, or right-lateral position (n = 43 for each group). Laryngeal views were obtained in the designated position with a Macintosh laryngoscope, and patients' tracheas were subsequently intubated with the Airway Scope. Specifically, we tested the hypothesis that the time required for intubation in the left- and right-lateral positions is not increased by >10 seconds compared with tracheal intubation in the supine position.

RESULTS

Overall intubation success was 100% in the 2 lateral positions, and 98% in the supine position. Intubation times were similar in the left-lateral (24 [5] seconds, mean [SD]), right-lateral (24 [6] seconds), and supine (22 [7] seconds) positions. The numbers of required intubation attempts were similar in the 2 lateral positions and in the supine and left-lateral positions. However, more intubation attempts were required in the supine position than in the right-lateral position (P = 0.004). The incidences of airway complications were similar in each position; no hypoxia, dental injury, or esophageal intubation was observed. Modified Cormack-Lehane and the percentage of glottic opening scores obtained with the Macintosh laryngoscope did not differ between the 2 lateral positions, but the modified Cormack-Lehane and percentage of glottic opening scores were superior in the supine position (all P < 0.001) compared with either of the lateral positions.

CONCLUSIONS

Despite worse laryngoscopic views in either lateral position than when patients were supine, intubation with the Airway Scope offered high success rates. Furthermore, intubation time using the Airway Scope in either lateral position was not longer by >10 seconds than in the supine position. The Airway Scope thus seems to be a useful tool when tracheal intubation is required in a laterally positioned patient.

Pentax-airway scope for tracheal intubation breaks through the limitation of neck motion in an ankylosing spondylitis patient wearing halo vest--a case report

The Airway Scope (AWS) provides better glottic view than the conventional direct laryngoscopy in tracheal intubation. With it, the endotracheal tube can be more easily inserted into the tracheal lumen easily. We hereby presented a 24-year-old ankylosing spondylitis (AS) patient wearing a halo vest who was successfully intubated for undergoing cervical spine surgery involving C1 and C2 under general anesthesia. Pre-operative airway assessment revealed that he was a case of difficult intubation. An AWS was used for oral tracheal intubation which was achieved smoothly in the first attempt. AWS can be an alternative device for airway management in a patient wearing halo vest.

Assessment of the storz video Macintosh laryngoscope for use in difficult airways: A human simulator study

OBJECTIVES

Video laryngoscopy has been shown to improve glottic exposure when compared to direct laryngoscopy in operating room studies. However, its utility in the hands of emergency physicians (EPs) remains undefined. A simulated difficult airway was used to determine if intubation by EPs using a video Macintosh system resulted in an improved glottic view, was easier, was faster, or was more successful than conventional direct laryngoscopy.

METHODS

Emergency medicine (EM) residents and attending physicians at two academic institutions performed endotracheal intubation in one normal and two identical difficult airway scenarios. With the difficult scenarios, the participants used video laryngoscopy during the second case. Intubations were performed on a medium-fidelity human simulator. The difficult scenario was created by limiting cervical spine mobility and inducing trismus. The primary outcome was the proportion of direct versus video intubations with a grade I or II Cormack-Lehane glottic view. Ease of intubation (self-reported via 10-cm visual analog scale [VAS]), time to intubation, and success rate were also recorded. Descriptive statistics as well as medians with interquartile ranges (IQRs) are reported where appropriate. The Wilcoxon matched pairs signed-rank test was used for comparison testing of nonparametric data.

RESULTS

Participants (n = 39) were residents (59%) and faculty. All had human intubation experience; 51% reported more than 100 prior intubations. On difficult laryngoscopy, a Cormack-Lehane grade I or II view was obtained in 20 (51%) direct laryngoscopies versus 38 (97%) of the video-assisted laryngoscopies (p < 0.01). The median VAS score for difficult airways was 50 mm (IQR = 28–73 mm) for direct versus 18 mm (IQR = 9–50 mm) for video (p < 0.01). The median time to intubation in difficult airways was 25 seconds (IQR = 16–44 seconds) for direct versus 20 seconds (IQR = 12–35 seconds) for video laryngoscopy (p < 0.01). All intubations were successful without need for an invasive airway.

CONCLUSIONS

In this simulation, video laryngoscopy was associated with improved glottic exposure, was perceived as easier, and was slightly faster than conventional direct laryngoscopy in a simulated difficult airway. Absence of secretions and blood limits the generalizability of our findings; human studies are needed.

Airway scope and Macintosh laryngoscope for tracheal intubation in patients lying on the ground

BACKGROUND

Direct laryngoscopy of a patient lying on the ground is difficult because the intubator's head is far above the head of the patient, making alignment of the intubator's visual axis with the patient's tracheal axis difficult. The Airway Scope is a laryngoscope designed to facilitate tracheal intubation without requiring alignment of the oral, pharyngeal, and tracheal axes. We thus tested the hypothesis that intubation with the Airway Scope is faster than with the Macintosh laryngoscope in subjects lying on the ground.

METHODS

Adult surgical patients were enrolled. After anesthesia induction, direct laryngoscopy was performed and airway characteristics noted. Patients were randomly assigned to tracheal intubation by either the Airway Scope (n = 50) or the Macintosh laryngoscope (n = 50). The intubator performed tracheal intubation from a table positioned at the same height as that of the operating table, thus simulating intubating on the ground. An unblinded observer recorded overall intubation success rate, time required for intubation, the number of attempts required for successful intubation, and airway complications related to intubation. Of these, the primary end point was time required for intubation.

RESULTS

Overall intubation success rates were 98% with the Airway Scope and 100% with the Macintosh laryngoscope. Intubation was 17 s faster with the Airway Scope (mean, 18 (SD, 4) seconds) versus the Macintosh laryngoscope (35 (16) seconds). The number of intubation attempts was similar with each device. The incidences of airway complications were similar, with no hypoxia (Spo(2) <95%) occurring in either group.

CONCLUSIONS

Both the Airway Scope and the Macintosh laryngoscope offer high success rates in adequately prepared paralyzed patients lying supine at ground level in the hands of a skilled practitioner. However, the Airway Scope facilitated faster tracheal intubation.

Effect of cardiopulmonary resuscitation on intubation using a Macintosh laryngoscope, the AirWay Scope, and the gum elastic bougie: A manikin study

BACKGROUND

Physicians could encounter difficult intubation during cardiopulmonary resuscitation (CPR) in trauma patients due to the patient's movement from continuous chest compression and to cervical stabilisation. Therefore, first, we evaluated the impact of chest compression with or without cervical stabilisation on intubation with a Macintosh laryngoscope. Next, we compared difficulty in intubation among the Macintosh laryngoscope, AirWay Scope (AWS), and gum elastic bougie (GEB) with the Macintosh laryngoscope in three simulated CPR scenarios in a randomised, controlled, cross-over study design.

METHODS

Twenty-three anaesthetists intubated the trachea of a manikin (ALS Skill Master, Laerdal Medical Japan, Tokyo, Japan) using the Macintosh laryngoscope, AWS, and GEB in the control scenario, chest compression scenario, and chest compression with cervical stabilisation scenario. Difficulty in intubation was rated on a 5-point scale and the intubation time was measured.

RESULTS

Continuous chest compression increased difficulty in intubation with the Macintosh laryngoscope, compared with the control scenario. Concurrent application of cervical stabilisation further increased the difficulty, compared with application of chest compression alone. Of the three devices compared, the AWS facilitated the easiest intubation, and the GEB facilitated the second-easiest intubation in all scenarios, though the intubation time was slightly longer with the GEB than with other devices.

CONCLUSION

CPR employing continuous chest compression with or without cervical stabilisation caused difficult intubation with the Macintosh laryngoscope. The AWS and GEB facilitated the easiest and second-easiest intubation, respectively, even during CPR employing continuous chest compression with or without cervical stabilisation in a manikin.

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

PURPOSE

The 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.

METHODS

Fourteen 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".

RESULTS

In 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.

CONCLUSION

We conclude that the AWS is an effective device for endotracheal intubation during chest compression not only on the bed but also on the ground.

Tracheal intubation using Macintosh and 2 video laryngoscopes with and without chest compressions

PURPOSE

The aim of the study was to compare the time taken for intubation (TTI) using the Macintosh and 2 video laryngoscopes (VLs) (GlideScope [GVL]; Saturn Biomedical System, Burnaby, British Columbia, Canada, and Airway Scope [AWS]; Pentax, Tokyo, Japan) with and without chest compressions by experienced intubators in a mannequin model.

METHODS

This was a randomized crossover study. Twenty-two experienced physicians who have limited experience in the VLs participated in the study. The TTI using 3 laryngoscopes with and without compressions were compared.

RESULTS

Median TTI difference between 2 conditions was only significant in the AWS (1.64 seconds; P = .01). There were no significant differences in the TTI between the Macintosh and the GVL or the AWS during compressions.

CONCLUSION

In a mannequin model, the Macintosh or the GVL was not affected by chest compressions. The TTI using the AWS was delayed by compressions but not clinically significant. Considering the lack of experience, 2 VLs may be useful adjuncts for intubation by experienced intubators during chest compressions.

Tracheal intubation of a difficult airway using Airway Scope, Airtraq, and Macintosh laryngoscope: a comparative manikin study of inexperienced personnel

BACKGROUND

The Airway Scope (AWS) (Pentax-AWS, Hoya Corp., Tokyo, Japan) and the Airtraq (ATQ) (Prodol, Vizcaya, Spain) have similarities in the novel structures of their blades. In this study, we evaluated the ease of use of the AWS and ATQ compared with the Macintosh laryngoscope (ML) by inexperienced personnel in a simulated manikin difficult airway.

METHODS

Twenty-four fifth-year medical students with no previous experience in tracheal intubation participated in this study. We used an advanced patient simulator (SimMan(R), Laerdal Medical, Stavanger, Norway) to simulate difficult airway scenarios including cervical spine rigidity, limited mouth opening, and pharyngeal obstruction. The sequences in selecting devices and scenarios were randomized. Success rates for tracheal intubation, and the time required for visualization of the glottis, tracheal intubation, and inflation of the lungs, and the number of optimization maneuvers and dental click sounds were analyzed. The 3 different intubation devices were tested in 4 different scenarios by 24 students.

RESULTS

Both the AWS and ATQ had very high success rates of tracheal intubation compared with the ML (AWS 100%*; ATQ 98%*; and ML 89%; *P < 0.05 AWS, ATQ versus ML). The time to intubation with the AWS was significantly shorter than with the ATQ and ML (AWS 11 +/- 6 seconds; ATQ 16 +/- 12 seconds; and ML 16 +/- 11 seconds; *P < 0.05 AWS versus ATQ, ML). The number of optimization maneuvers with the AWS was significantly lower than with the ATQ and ML. There were significantly more audible dental click sounds with the ML than with the AWS and ATQ.

CONCLUSION

Both the AWS and ATQ may be suitable devices for difficult intubation by inexperienced personnel in this manikin simulated scenario. Further studies in a clinical setting are necessary to confirm these findings.

Comparison of the Pentax Airway Scope and McGrath Videolaryngoscope with the Macintosh laryngoscope in tracheal intubation by anaesthetists unfamiliar with videolaryngoscopes: a manikin study

Videolaryngoscopes are becoming widely available and have been suggested as a replacement for the Macintosh in cases of cervical instability or even for use in the first instance. There is limited existing data on the use of videoscopes by experienced anaesthetists who are inexperienced in the use of videoscopes. We used a manikin model to compare time to intubation between the Macintosh blade, Pentax Airway Scope and the McGrath videolaryngoscope in a simulated urgent intubation by 23 experienced anaesthetists with no prior experience in the use of these videoscopes. We also measured the number of attempts and success of intubation within three minutes. Ease of device use and laryngoscopic view obtained were also recorded. We found that all participants could intubate the manikin within three minutes, with a median of one attempt using the Pentax Airway Scope. Only 48% of participants (n=11) could intubate within three minutes using the McGrath videolaryngoscope and required a median of three attempts. This difference occurred despite the majority of anaesthetists obtaining a Grade 1 Cormack and Lehane view with both videoscopes. We demonstrated that anaesthetists who were naive to these videoscopes can successfully intubate the trachea using the Pentax Airway Scope but not the McGrath videolaryngoscope.

Displacement of the epiglottis during intubation with the Pentax-AWS Airway Scope

The Pentax-AWS system is a rigid indirect video laryngoscope with integrated tube guidance. Complications associated with this device are not well understood. We report two cases of epiglottis malposition during intubation with the Pentax-AWS. The standard technique of using the Pentax-AWS system involves direct elevation of the epiglottis for exposure of the vocal cords. The blade tip should be passed posterior to the epiglottis for laryngeal exposure, but pressure on the anterior surface of the epiglottis by the tip can rarely happen even during the correct maneuver. Although the Pentax-AWS provides clear images of the airway structures, it is sometimes difficult to observe the epiglottis continuously because the camera is located beneath the blade tip. Consequently, the view of the epiglottis from the camera may be impeded by the blade tip and may result in undiagnosed epiglottis malposition. The AWS's structural feature and its approach to the larynx can be associated with increased chance of unexpected epiglottis folding. It is particularly important to confirm normal position of the epiglottis during withdrawal of the device to prevent this complication.

Randomized controlled trial of intubation with the McGrath Series 5 videolaryngoscope by inexperienced anaesthetists

BACKGROUND

The McGrath Series 5 videolaryngoscope might reduce the incidence of unexpected difficult tracheal intubation. If it also performs as well as a standard laryngoscope during uncomplicated intubations, there would be an argument for the McGrath to become the laryngoscope of choice in higher risk settings, such as rapid sequence induction by inexperienced anaesthetists. Therefore, we compared the McGrath and the Macintosh laryngoscopes during routine tracheal intubation performed by inexperienced anaesthetists.

METHODS

Single-blind randomized controlled trial with 120 adult patients allocated to intubation by first-year anaesthetic trainees, using a McGrath or Macintosh laryngoscope. The primary outcome was time to intubation. Secondary outcomes were quality of view at laryngoscopy and evidence of differential learning between using the two laryngoscopes. A Cox proportional hazards model was used to determine the effect of the laryngoscopes on time to intubation.

RESULTS

Duration of intubation was significantly longer (P<0.001) in the McGrath group [median (IQR); 47.0 (39.0-60.0) vs 29.5 (23.0-36.8) s]. There were no significant differences in other outcomes, including grade of laryngoscopy view, visual confirmation of tube placement, number of laryngoscopies, or complications (oesophageal intubation, hypoxaemia, and airway trauma). There was no differential learning effect.

CONCLUSIONS

There were no advantages to using the McGrath laryngoscope for uncomplicated tracheal intubation and duration of intubation was longer, so it should not be used as a first-line laryngoscope instrument by inexperienced anaesthetists.

A comparison of Truview infant EVO2 laryngoscope with the Miller blade in neonates and infants

BACKGROUND

The Truview EVO2 laryngoscope is a recently introduced device with a unique blade that provides a wide and magnified laryngeal view at 46 degrees anterior refracted angle. An infant blade of the laryngoscope has recently become available.

AIMS AND OBJECTIVES

The aim of the study was to compare the Truview infant EVO2 laryngoscope with the Miller straight blade laryngoscope in order to determine whether the Truview EVO2 laryngoscope provided an improved laryngeal view at laryngoscopy and also to assess the time taken for intubation with the two devices.

MATERIALS AND METHODS

In this prospective randomized study, 60 neonates and infants of either sex undergoing surgery under general anesthesia were enrolled and divided into two groups: endotracheal intubation using a Truview infant blade (Group I) or with a Miller blade number 0 (Group II). The view of the glottis at laryngoscopy, time to intubation and the number of attempts required for intubation were recorded.

RESULTS

The average time for laryngoscopy in Group I was 18.18 s and in Group II was 16.30 s, which though not significant clinically, is statistically significant (P = 0.002). While eight patients (26.6%) had Cormack and Lehane grade 2 view on laryngoscopy in Group II, only two patients (6.6%) had such a view in Group 1 (P = 0.039). The number of attempts at laryngoscopy was comparable in the two groups.

CONCLUSION

In this study, we found that in neonates and infants, the tracheal intubation using Truview infant EVO2 blade took almost as much time as miller blade and provided improved laryngoscopic view as compared to the Miller blade.

A comparative study on the efficacy and cardiovascular response generated by macintosh and pentax-AWS video laryngoscopic endotracheal intubation methods

BACKGROUND

The Pentax-AWS is a newly developed rigid video laryngoscope. In comparison to the Macintosh laryngoscope, it offers a significantly improved laryngeal view and facilitates endotracheal intubation. The present study was performed to compare the general efficiency and the cardiovascular responses generated by Macintosh and Pentax-AWS systems during endotracheal intubation.

METHODS

This study included 120 patients with American Society of Anesthesiologists (ASA) physical status class 1 or 2 requiring tracheal intubation for elective surgery. All patients were randomly allocated into two groups: Pentax-AWS (group P) and Macintosh (group M). Induction of anesthesia was performed using fentanyl, thiopental and succinylcholine intravenously. Systolic, mean and diastolic blood pressure (SBP, MBP, DBP) and heart rate (HR) were recorded just prior to induction, 1, 3, and 5 minutes after intubation.

RESULTS

There were no significant differences in SBP, MBP, DBP and HR between both groups. However, group P showed a higher POGO (Percentage of Glottic Opening) score than group M during endotracheal intubation.

CONCLUSIONS

Use of Pentax-AWS in endotracheal intubation did not increase hemodynamic changes compared to the use of Macintosh laryngoscope. Furthermore, Pentax-AWS offered an improved laryngeal view during endotracheal intubation.