Yu J. Yuan

Cuff inflation as an aid to nasotracheal intubation using the Airtraq laryngoscope.

To the Editor, The Airtraq laryngoscope (Prodol Meditec S.A., Biscay, Spain) is a new disposable optical laryngoscope with the ability to provide a full view of the glottis without the necessity to align oral, pharyngeal, and laryngeal axes. This device has been used successfully for orotracheal and nasotracheal intubation (NTI) in an uncomplicated or difficult airway. 1-4 Also, a mannequin study suggests that the Airtraq laryngoscope offers potential advantages over standard direct laryngoscopy for NTI. 5 However, when NTI is performed with the Airtraq laryngoscope, we find that difficulty in directing the tube tip into the visualized glottis is a common problem. Here, we report our experience using a cuff inflation technique to address this issue. After local ethics committee approval and written informed consent, we recruited 72 patients (29 males and 43 females) into the study. The patients, ASA physical status I-II and aged 18 to 51 yr, were scheduled for elective oral and maxillofacial surgery under general anesthesia with NTI to optimize the surgical approach. Exclusion criteria included patients with a known or predicted difficult airway and those with a history of severe nasal trauma and recurrent epistaxis. In this study, we used the Portex polar preformed cuffed nasotracheal tubes with inner diameters of 7.0 and 6.5 mm (Portex, Keene, NH, USA) for male and female patients, respectively. Prior to NTI, the patients’ nasal passages were prepared with vasoconstrictor and water-soluble jelly. All tracheal intubations were performed by an anesthesiologist (F.S.X.) who had been trained on the use of an Airtraq laryngoscope in a shortterm airway management program and who had performed the NTI using this device in more than 20 patients prior to this study. After anesthesia induction and establishing mask ventilation, a nasotracheal tube was inserted via the preselected nostril until the tube tip passed through the posterior naris. Next, an orotracheal Airtraq laryngoscope was passed into the patient’s mouth over the tongue in the midline. After the distal end of the Airtraq laryngoscope was positioned in the vallecula with the glottis in the centre

Nasotracheal intubation using the Airtraq® optical laryngoscope in patients with a difficult airway

To the Editor, We were interested in a recently published case report describing application of the Airtraq optical laryngoscope (Airtraq) for nasotracheal intubation (NTI) in a patient with a predicted difficult airway who was undergoing oral surgery. The authors are to be congratulated on their successful airway management in this challenging case. However, topical anesthesia was performed on only the naris and nasopharynx. In our experience, topical anesthesia of the trachea is also important for successful tracheal intubation and to ensure comfort of the awake patient. Moreover, insertion of a MADgic laryngotracheal atomizer (MAD-LTA) (Wolfe Tory Medical Inc., Salt Lake City, UT, USA) through the oral and nasal cavities for topical anesthesia of the supraglottic, glottic, and infraglottic areas can be performed quite easily under the visual field of the airway provided by the Airtraq. This technique is well tolerated by the awake sedated patient, possibly due to less stimulation of the oropharyngolaryngeal structures during laryngeal exposure using the Airtraq, as it does not require a ‘‘line of sight’’ to visualize the airway anatomy. In cases where there was difficulty in directing the nasotracheal tube tip into the glottis under direct vision with the Airtraq, the authors used a flexible nasotracheal tube rather than a preformed tube to insert the fibreoptic bronchoscope (FOB). Preformed nasotracheal tubes are very useful for patients undergoing head and neck surgery because they are easy to secure, they provide convenient surgical access, and they may reduce pressure on the nares. We previously reported methods to improve use of preformed nasotracheal tubes during FOB-guided NTI. Our experience suggests that difficulty in directing the tube tip into the visualized glottis can be challenging when NTI is performed with the Airtraq, especially for pediatric patients. To address this problem, we have used all the techniques described in the recent case report. In some cases, we have found external laryngeal manipulation to be useful in locating the lateral tube tip. Although the nasal version Airtraq provides additional space to facilitate passage of Magill forceps in the absence of a posterior tubeguiding channel, the greater distal angulation of its blade may render their use very awkward. Furthermore, use of Magill forceps can occasionally result in cuff damage. Combined use of the Airtraq and a FOB can enable successful NTI in patients with difficult airways, but disadvantages of this method include the need of two experienced anesthesiologists during tracheal intubation and complex cleaning and sterilization procedures after tracheal intubation. In our practice, the Airtraq and a FOB are used in combination in any situation where the operator is unable to visualize the glottis by the viewfinder, either with or without the epiglottis, i.e., either a CormackLehane grade 3 or grade 4 view via the Airtraq. If only the nasotracheal tube tip is excessively posterior or lateral to the glottis under the Airtraq visualization, we prefer to use a cuff inflation technique to align the tube tip with the glottis. When only a Cormack-Lehane grade 2 view is obtained using the Airtraq or when the glottis is off-centre of the viewfinder, we have recently combined use of the Airtraq and the Eschmann Tracheal Tube Introducer (gum elastic Fu S. Xue and Xu Liao contributed equally to this work.

Facilitating combined use of an Airtraq® optical laryngoscope and a fiberoptic bronchoscope in patients with a difficult airway

To the Editor, We congratulate Drs. Gomez-Rios and Nieto Serradilla on their successful tracheal intubation using a combination of an Airtraq optical laryngoscope (Airtraq), Airtraq video camera, Airtraq wireless monitor (Prodol Meditec S.A., Vizcaya, Spain), and a fibreoptic bronchoscope (FOB) after failed intubation in a patient with a grossly distorted airway due to compression by a cervical tumour. We too have employed this combined technique in both adult and pediatric patients with difficult airways. In our experience, an important advantage of this approach is the ease and precision of FOB-guided intubation using the Airtraq; inserting the Airtraq to lift the patient’s tongue and jaw can achieve a clear airway for fibroscopy. Furthermore, by providing a clear view of the airway, the external monitor allows the FOB and Airtraq operators to observe simultaneously each step during the procedure. This approach is especially suitable in situations where the glottis cannot be visualized adequately by the Airtraq, either with or without the epiglottis, i.e., in a CormackLehane grade 3 or grade 4 view. In their report, the authors do not specify the type and manufacturer of the FOB used in this case. From Panel C of the Figure, we speculate that an adult FOB with an outer diameter of at least 4 mm was inserted through a 7.0-mm polyvinyl chloride endotracheal tube (ETT) mounted in the guiding channel. Also, the ETT tip was placed within the vicinity of the glottis during fibroscopy. Our experience suggests that inserting a large FOB via the ETT and placing the ETT tip close to the glottis can cause difficulties in performing fibroscopy and in directing the FOB tip into the glottis. Maneuverability of the anterior bending section of the FOB is decreased by limiting the spaces between the inner wall of the ETT and the outer wall of the FOB and between the glottis and the ETT tip. In our practice, when tracheal intubation with an Airtraq fails, we prefer to use two approaches to facilitate FOBguided intubation using the Airtraq: 1) If the operator plans to insert a FOB through the ETT mounted in the guiding channel, the ETT tip should be placed just at the distal end of the guiding channel to obtain an adequate space for the fibroscope. A small FOB is recommended to improve maneuverability of the fibroscope (Figure). 2) If a small FOB is not available, we suggest to withdraw the ETT from the guiding channel and to thread the ETT over a large FOB. The FOB loaded with the ETT can then be passed through the guiding channel toward the larynx. After the larynx is exposed by fibroscopy, the FOB can be advanced into the trachea through the glottis, and subsequently, the ETT can be railroaded over the FOB within the guiding channel into the trachea. With this approach, it is relatively easy to perform fibroscopy with the FOB and to insert the FOB and the ETT into the trachea.

Performance of the GlideRite® Rigid Stylet and malleable stylet for tracheal intubation by novices using the GlideScope® videolaryngoscope

To the Editor, In the very interesting article by Jones et al. comparing the GlideRite Rigid Stylet and the standard malleable stylet to facilitate tracheal intubation by novices using the GlideScope videolaryngoscope (GVL), anesthesiology trainees were defined arbitrarily as novice GVL operators if they had performed ten or fewer GVL intubations. In our view, the definition of novice GVL operators used in this study has several limitations. First, novices who use the GVL experience a rapid learning curve. Nouruzi-Sedeh et al . demonstrated that medical personnel untrained in tracheal intubation required only five tracheal intubation attempts to achieve proficiency with the GVL in patients with a normal airway. Second, the authors did not report the experience of the anesthesiology trainees in tracheal intubation with direct laryngoscopes. Since the GVL and direct laryngoscopes share many common features, operators with some experience in performing tracheal intubation with direct laryngoscopy are able to use the GVL successfully without need for special training. Furthermore, anesthesiologists with no prior experience using the GVL have been shown to achieve a 100% success rate performing tracheal intubation, including a 97% success rate at first attempt. When interpreting the results of Jones et al.’s study, one other issue that merits consideration is the type of GVL device they evaluated. Currently, three types of GVL devices are available: the conventional GVL, the Cobalt GVL, and the Ranger GVL. Furthermore, there are two to three reusable blades or disposable blades available for each of these three devices for adult patients (Verathon Medical Inc., Bothell, WA, USA; http://verathon.com/lan guage/en-us/products/glidescope.aspx). The shapes, lengths, and angulations of the blades vary amongst the three GVL devices and between the reusable and disposable GVL blades. The Cobalt GVL and the conventional GVL have been shown to have similar performance characteristics, but a previous study compared only a size 5 conventional GVL blade with a size 4 disposable Cobalt GVL blade. The blind spot appearing below the GVL blade tip differs according to the different blade sizes. Taking these issues into consideration, we suggest cautious interpretation of studies evaluating outcomes in airway management for novice operators using the GVL.

Rational design of end-points to evaluate performance of the C-MAC D-blade videolaryngoscope during routine and difficult intubation.

1. Pivalizza EG, Gumbert SD, Maposa D. Is hand contamination of anesthesiologists really an “important” risk factor for intraoperative bacterial transmission? Anesth Analg 2011;113:202–3 2. Loftus RW, Koff MD, Burchman CC, Schwartzman JD, Thorum V, Read ME, Wood TA, Beach ML. Transmission of pathogenic bacterial organisms in the anesthesia work area. Anesthesiology 2008;109:399–407 3. Muffly MK, Beach ML, Tong YC, Yeager MP. Stopcock lumen contamination does not reflect the full burden of bacterial intravenous tubing contamination: analysis using a novel injection port. Am J Infect Control 2010;38:734–9 4. Koff MD, Loftus RW, Burchman CC, Schwartzman JD, Read ME, Henry ES, Beach ML. Reduction in intraoperative bacterial contamination of peripheral intravenous tubing through the use of a novel device. Anesthesiology 2009;110:978–85 DOI: 10.1213/ANE.0b013e31821d0b40

Comparison of safety and efficacy of Supreme laryngeal mask airway and ProSeal laryngeal mask airway.

Editor, The recent article of Seet et al. comparing the safety and efficacy of Supreme laryngeal mask airway (LMA) and ProSeal LMA in a randomized controlled trial was of great interest to us. The results of this study showed that compared with ProSeal LMA, Supreme LMA had a lower oropharyngeal leak pressure and a higher success rate of the first insertion attempt. However, several design aspects of this study should be clarified.

Tracheal intubations performed with a Macintosh laryngoscope and videolaryngoscopes on a mannequin simulating cardiac arrest

To the Editor, In a randomized crossover trial on a mannequin simulating cardiac arrest, Shin et al. showed that tracheal intubation, during chest compressions under conditions of both normal and difficult airways, was more successful with either the Pentax-AWS or the GlideScope videolaryngoscope (97-100% success rate) than with the Macintosh laryngoscope (75-97% success rate). However, apart from the limitations described in the Discussion section of their manuscript, we note one issue in this study which may confound interpretation of the results. In this study, the participants were inexperienced junior interns who were given a standardized 20-min training session on each of the devices before the study. The authors ignored an important issue, namely, a different learning curve is required for each of the three devices. NouruziSedeh et al. showed that untrained personnel required only five tracheal intubation attempts to achieve proficiency with the GlideScope in patients with a normal airway. Also, Hirabayashi found that a short demonstration of the Pentax-AWS and a brief practice with a mannequin were the only requirements needed to perform a tracheal intubation with the device. However, in the studies of Mulcaster et al. and Konrad et al., novice anesthesia residents or non-anesthesia trainees required 47-56 tracheal intubations to achieve a tracheal intubation success rate of C 90% using direct laryngoscopy. These findings suggest that less training is required to achieve proficiency with the Pentax-AWS and the GlideScope than with the direct laryngoscope. Furthermore, when the Pentax-AWS was compared with the GlideScope in both simulated normal and difficult airway scenarios, novice operators found it easier to intubate the trachea with the PentaxAWS . Thus, in Shin et al.’s study, identical training times for the three devices may have biased both the time required for tracheal intubation and the success rate in favour of the two videolaryngoscopes, especially for the difficult airway scenario. To be precise, the differences in the performance of the three laryngoscopes may be attributed to their different learning curves. The findings of Kim et al. support this view. They studied emergency physicians— who had performed [ 50 tracheal intubations with the direct laryngoscopy on a mannequin simulating cardiac arrest— after the physicians had received only a one-hour training session with the GlideScope and the Pentax-AWS , and they found no significant differences between the Macintosh laryngoscope, the Pentax-AWS , and the GlideScope in terms of intubation time during chest compression. The different learning curves might explain the inconsistent results between studies on a mannequin simulating cardiac arrest.

Performance of Single-Use and Reusable Metal Blades for Emergency Tracheal Intubation in the Out-of-Hospital Setting

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Notes on Tracheal Intubation With Indirect Laryngoscopes

To the Editor: In the excellent review by Levitan et al about the complexities of tracheal intubation with direct laryngoscopy and alternative intubation devices, several aspects of their comments with indirect laryngoscopes should be discussed. The authors comment that the cameras used by the McGrath, GlideScope, and Storz C-MAC devices have a wide field of view both up and down and left to right that includes the distal tip of their blades. Our experience and research do not support their findings. First, the anterior part of the left side of the blade is in front of the camera or extended to the distal tip, despite that its width gradually decreases. Thus, the left field of view of a camera within the blade can be limited by the anterior part of the left side of the blade. Second, other than orientation of the imaging device, the field of view provided by a video laryngoscope is also affected by the position of the camera in the blade and shape of the blade. In the GlideScope (size 4), McGrath, and C-MAC, the cameras are positioned at 5.5, 4.5, and 3.5 cm from the blade tips, respectively. Also, distal curvatures of the blades are significantly different among 3 videolaryngoscopes: GlideScope greater than McGrath greater than C-MAC. One can imagine that if a camera is placed at a site far from the tip of an excessively curved blade, such as GlideScope, the camera’s field of view cannot cover the distal tip of the blade, resulting in a blind area just below the blade tip. It has been shown that the blind area of the camera below the blade tip is 2 and 13 mm in smalland medium-sized reusable GlideScope blades, respectively. By measurements, we further find that this blind area is more than 10 mm in sizes 4 and 5 reusable GlideScope blades. In contrast, the blind area of the camera below the blade tip is only 3 mm in McGrath and 0 mm in C-MAC, which may be because curvatures of their blades are not as great and the cameras are closer to the blade tip compared with that of the GlideScope. Although a small blind area below the blade tip may not interfere with laryngoscopy and tracheal intubation with a videolaryngoscope, a large blind area can result in difficulty in some cases, especially in patients with an anteriorly positioned glottis, which may be one of the reasons that the GlideScope cannot adequately expose the larynx in certain cases. A recent study showed that inadequate laryngeal views provided by GlideScope contributed to 55% of failed tracheal intubation (33 of 60 patients). As for the GlideRite stylet, the manufacturer indeed provides a distal curvature of approximately 70 degrees because it can create a tube shape essentially matching the GlideScope blade shape. In a heterogeneous group of operators and patients p

Comments on comparison of Bonfils fiberscope-assisted laryngoscopy with standard direct laryngoscopy in simulated difficult pediatric intubation.

and found both failure rate and inadvertent carotid puncture to decrease when prelocation was used but these outcomes were not affected by the use of intraoperative ultrasound guidance. Again, it is important to note that these analyses included two studies where the ultrasound guidance was performed by fellows and the Grebenik study. Meta-analysis, after exclusion of this study, found both failure rate and inadvertent carotid puncture to decrease when ultrasound guidance was performed by fellows (OR = 0.11 [0.02–0.52], I = 0%, P = 0.38, OR = 0.11 [0.02–0.48], I = 0%, P = 0.34, respectively). In 2008, Roth et al. (3) performed a study to determine the anatomical relationship of the internal jugular vein and the common carotid artery in preschool children using ultrasound. This study demonstrates that the internal jugular vein covers the carotid artery in the majority of young children but anatomical variations are not unusual. The finding of this study supports the use of ultrasound guidance in children. Leyvi et al. in 2005 retrospectively analyzed a series of 149 patients and compared the ultrasound-guided and the Landmark-guided techniques. This study was certainly limited by its retrospective nature but they demonstrate that ultrasound-guided cannulation achieves a higher success rate for less-experienced operators in children (4). In conclusion, results of this excellent meta-analysis have to be interpreted with caution because the methodology of the included studies varied. Real time visualization of the vessels and their anatomical situation could increase the quality of the vein cannulation and is helpful for those who know how to handle the probe. The benefit is probably lesser for practitioners whose usual practice is to perform the cannulation by using the Landmark and who have a lot of experience with the landmark-technique. D A V I D F A R A O N I Department of anesthesiology, CHU-Brugmann – HUDE RF, Brussels, Belgium (email: David.Faraoni@ulb.ac.be).