Jian-Hua Liu

Oxygen flush is an effective means to eliminate obscured vision by fogging during intubation using the Airtraq® optical laryngoscope

To the Editor, The Airtraq optical laryngoscope (Airtraq) (Prodol Meditec S.A., Vizcaya, Spain) is a new disposable tracheal intubation device with an anatomically-shaped blade that contains two parallel channels, the optical channel and the guiding channel, which accommodates the endotracheal tube (ETT). The image is transmitted to a proximal viewfinder, and the distal viewing lens allows visualization of the larynx and advancement of the ETT. In addition, the Airtraq has a warming element at the blade tip. According to the manufacturer’s manual, the Airtraq light should be turned on at least 30 sec before use to allow heating of the viewing lens and to prevent fogging. Despite the Airtraq’s anti-fog mechanism, we have observed that visualization of the laryngeal inlet can be obscured by fogging on the viewing lens, especially when tracheal intubation time is prolonged in patients with difficult airways. To resolve this issue, and in view of previous experience with another optical laryngoscope (Truview laryngoscope, Truphatek International Ltd, Netanya, Israel) and the fibreoptic laryngoscopes, we tested the effectiveness of using highflow oxygen to eliminate fogging during laryngoscopy and tracheal intubation using the Airtraq. After receiving local ethics committee approval and written informed consent, we recruited 321 children (aged three months to 17 yr) and 283 adults (aged 18-75 yr) into the study. All of the patients were American Society of Anesthesiologists’ physical status I-II patients who were scheduled for elective plastic surgery in our hospital from March 2009 to June 2010. All procedures called for general anesthesia requiring tracheal intubation. Exclusion criteria included patients with a limited mouth opening that precluded insertion of the Airtraq and refusal to participate in the study. All intubations were performed by anesthesiologists who had been trained in the use of an Airtraq in a short-term airway management program and who had performed tracheal intubations using this device in more than 20 patients prior to this study. Induction and maintenance of anesthesia were not standardized but were left to the discretion of the staff anesthesiologist to use either a propofol or sevofluranebased technique with or without neuromuscular blockade. Before orotracheal intubation, an appropriately-sized ETT was loaded into the guiding channel of the Airtraq, and the ETT tip was positioned at the right side of the viewing lens. When performing nasotracheal intubation, the ETT was inserted via the pre-selected nostril until its tip passed through the posterior naris. The Airtraq was then passed into the patient’s airway over the tongue in the midline. Once the Airtraq blade tip was positioned in the vallecula with the glottis in the centre of the viewfinder, the ETT was passed by the glottis and advanced downwards into the trachea. Obscured vision during laryngoscopy and intubation was defined as fogging on the viewing lens that impeded continuous observation for airway structures and ETT advancement. Whenever this problem occurred, an assistant immediately attached the anesthesia circuit to the ETT. By intermittently pushing the oxygen flush valve of an anesthesia machine, a high oxygen flow was transported via the ETT to the distal end of the Airtraq to eliminate the fogging (Figure). The efficiency of de-fogging was assessed using a three-point scale (inefficient = no Fu Shan Xue, Jian-Hua Liu contributed equally to this work.

Facilitating tracheal intubation in pediatric patients with the Airtraq® optical laryngoscope

To the Editor, The Airtraq optical laryngoscope (Airtraq) (Prodol Meditec S.A., Vizcaya, Spain) is a relatively new disposable tracheal intubation device with an anatomically shaped blade that has two parallel channels, the optical channel and the guiding channel, which accommodates the endotracheal tube (ETT). The Airtraq incorporates a guiding channel to the right of the viewing axis to solve the challenge of passing the ETT through the glottis. However, delivering the ETT through the gap between the end of the guiding channel tube to the glottis may not be straightforward. The guiding channel tube and viewing axis are somewhat incongruent, because the direction of ETT advancement from the guiding channel is defined by the configuration of the guiding channel tube and the ETT angulation. When attempting to advance the ETT through the laryngeal aperture with the Airtraq during tracheal intubation, it has been reported that a posterior tube tip location can be problematic, especially for pediatric patients. On the basis of our cumulated experience with the Airtraq, which includes more than 500 pediatric patients to date, another possible difficulty in advancing the ETT through the glottis, especially in infants and young children with smaller airways, is a left tube tip location. This potential problem arises because the Airtraq is designed with the guiding channel at the right of the viewing axis, and a left-oriented slope at the right side of the distal opening of the guiding channel is devised to direct the tube tip into the glottis in the midline (Figure, Panel A). This design results in ETT advancement from the guiding channel towards the left. Consequently, during advancement of the ETT, the tube tip may move across the midline (Figure, Panel B) towards either the left vocal cord or the left laryngeal vestibule rather than align the ETT towards the midline of the glottis (Figure, Panel C). Whenever this problem arises, our practice has been to withdraw the ETT by approximately 0.5 cm and to exercise one of four available options: 1) slightly rotate the Airtraq in a clockwise direction; 2) advance the Airtraq downwards; 3) gently apply leftwards laryngeal pressure with external laryngeal manipulation, then re-attempt ETT advancement; and 4) in the very rare occasions the above measures fail, withdraw the ETT from the guiding channel and introduce a pediatric bougie into the visualized glottis via the guiding channel. The ETT is then railroaded along the bougie through the larynx, and the Airtraq is used to monitor the progress of the ETT advancement. Over the previous two years, we have used these maneuvers quite successfully to facilitate advancing the ETT into the glottis with the Airtraq device in pediatric patients with uncomplicated and difficult airways alike.

Facilitating endotracheal intubation using the GlideScope® video laryngoscope in children with difficult airways

into the trachea. • If the operator cannot visualize the glottis with or without the epiglottis by the viewfinder, i.e., a grade 3 or grade 4 view of the Airtraq laryngoscope, a pediatric FOB is inserted through the ETT (6). By rotation of the body of the FOB and manipulations of the tip control lever, the glottis is identified and the FOB is inserted into the trachea (Figure 1d). Then, the ETT is advanced over the FOB and inserted into the trachea. Several advantages of this combined use exist. First, the Airtraq laryngoscope can place the ETT tip in the immediate vicinity of the glottis, and the FOB may negotiate the sharp angle between the ETT tip and the glottis. Second, when the FOB operator manipulates it into position, the Airtraq laryngoscope operator may observe the location of the FOB tip by the viewfinder and give verbal feedback to the FOB operator. Third, the Airtraq laryngoscope can be used to monitor the placement of the ETT and find the cause of any resistance to advancement of the ETT over the FOB. F U S. X U E* N O N G H E† J I A N H. L I U* X U L I A O* X I U .Z . X U† Y A N M. Z H A N G* *Department of Anesthesiology Plastic Surgery Hospital Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China †Department of Anesthesiology Shou-Gang Hospital, Peking University Beijing, China (email: fruitxue@yahoo.com.cn)

An intraoral fixation method of endotracheal tube using the surgical suture in pediatric patients

tion of anaesthesia mask for fibreoptic intubation in children. Paediatr Anaesth 1999; 9: 119–122. 5 Holm-Knudsen R, Eriksen K, Rasmussen LS. Using a nasopharyngeal airway during fiberoptic intubation in small children with a difficult airway. Pediatr Anesth 2005; 15: 839– 845. 6 Paterson NA. Management of an unusual pediatric difficult airway using ketamine as a sole agent. Pediatr Anesth 2008; 18: 785–788. 7 Bryan Y, Chwals W, Ovassapian A. Sedation and fiberoptic intubation of a neonate with a cystic hygroma. Acta Anaesthesiol Scand 2005; 49: 122–123. 8 Smith JA, Santer LJ. Respiratory arrest following intramuscular ketamine injection in a 4-year-old child. Ann Emerg Med 1993; 22: 613–615. 9 Antila H, Laitio T, Aantaa R et al. Difficult airway in a patient with Marshall-Smith syndrome. Paediatr Anaesth 1998; 8: 429– 432. 10 Hostetler MA, Barnard JA. Removal of esophageal foreign bodies in the pediatric ED: is ketamine an option? Am J Emerg Med 2002; 20: 96–98.

Endotracheal intubation with Airtraq® optical laryngoscope in the pediatric patients

1 Jagannathan N, Kho MF, Kozlowski RJ et al. Retrospective audit of the air-Q intubating laryngeal airway as a conduit for tracheal intubation in pediatric patients with a difficult airway. Pediatr Anesth 2011; 21: 422–427. 2 Markakis D, Sayson S, Schreiner M. Insertion of the laryngeal mask airway in awake infants with the Robin sequence. Anesth Analg 1992; 75: 822–824. 3 Stricker P, Budac S, Fiadjoe J et al. Awake laryngeal mask insertion followed by induction of anesthesia in infants with the Pierre Robin sequence. Acta Anaesthesiol Scand 2008; 52: 1307–1308.

The lightwand-guided digital intubation in newborns and infants with difficult airways

with inhalational anesthetics with spontaneously breathing, laryngoscopy may make airway obstruction more serious or even cause total airway obstruction in a few children with micrognathia (3). This may be due to the reduced mandibular space with overcrowding of oropharyngolarygeal soft tissues in children with micrognathia, and laryngoscopy displacing the base of the tongue upwards and obstructing the laryngeal aperture. In contrast, we feel that use of a lightwand or rigid fiberoptic stylet helps to maintain a patent airway during intubation, even if when a partial airway obstruction exists during induction. This benefit may contribute to the two factors. (i)A firm anterocaudad jaw thrust, which is a necessary part of lightwand or rigid fiberoptic stylet guided intubation, helps to maintain a patent airway by elevating the epiglottis and expanding laryngopharyngeal space. (ii)During intubation, the precurved lightwand or rigid fiberoptic stylet with gentle anterior traction may pull the base of the tongue away from the laryngeal aperture. When faced with a failed laryngoscopic intubation in children with micrognathia, therefore, we often select the lightwand or rigid fiberoptic stylet guided intubation. As compared with the rigid fiberoptic stylet, moreover, we are more prone to use the lightwand because its use is easier and less affected by secretions or blood in the airway. In children with difficult airways due to craniofacial abnormalities, we have also successfully performed the lightwand guided intubation via the modified classic LMA with a shortened airway tube (Figure 1). F U S H A N X U E Y A N M I N G Z H A N G X U L I A O J I A N H U A L I U Department of Anesthesiology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (email: fruitxue@yahoo.com.cn)

Performance of GlideScope(®) videolaryngoscope for nasotracheal intubation in children.

not have either one of these pumps or remifentanil infusion rate table, some simple methods have been described (1). Here is an other practical method to calculate the dose quickly in milliliter per hour for pediatric patients. In our institute, we usually start remifentanil at 0.5 lgÆkgÆmin infusion rate for induction of balanced general anesthesia of pediatric patients and decrease the rate to 0.25–0.1 lgÆkgÆmin after intubation (approximately 4–6 min after initial rate), thus the patient is administered a 2–3 lgÆkg loading dose. According to our protocol, you can prepare 30 lgÆml remifentanil (usually 1500 lg drug in 50ml syringe), and then you can start the infusion at the numeric value of the patient’s weight in milliliter per hour. For example, if the patient’s weight is 17 kg, we start the infusion at 17 mlÆh and decrease the rate to half or 1/5 of it (8.5 or 3.4 mlÆh) for maintenance. As remifentanil is still an expensive drug, you may not want too much remaining waste drug (for short procedures and little children). In an operating room with a high turnover, you can prepare this 30 lgÆml solution in a 100 ml mediflex and obtain the appropriate volume according to patient’s weight and estimated surgery time. Also you can prepare the concentration 10 lgÆml (500 lg drug in 50-ml syringe), then for a 17 kg weight child, the rate will be 3 · 17 mlÆh for 0.5 lgÆkgÆmin infusion. More diluted solutions will prevent inadvertent bolus injections of high doses during inset of syringe to the pump or removal. Once the basic formula is memorized, multiplication or division can calculate higher or lower rates with higher or lower concentrations according to preferences. Standardization will reduce the incidence of mistakes during preparation of drugs.

Comparison of the intubation with the Storz video laryngoscope and standard direct laryngoscopy in pediatric patients

Additional Supporting Information may be found in the online version of this article: Figure S1. This is an example of the longitudinal dorsal cut in the shaft of the laryngeal mask airway (LMA) that is required for this procedure. Note, the endotracheal tube is positioned in this image to demonstrate the LMA modification and not to indicate how the tube would be advanced through the LMA. Please note: Wiley-Blackwell are not responsible for the content or functionality of any supporting materials supplied by the authors. Any queries (other than missing material) should be directed to the corresponding author for the article.

Comments on comparison of the combined Airtraq ® laryngoscope and a fiberoptic bronchoscope with the Airtraq ® alone for tracheal intubation

To the Editor: The recent article of Nishikawa et al. [1] comparing tracheal intubation by combined use of the Airtraq laryngoscope (Airtraq) and a fiberoptic bronchoscope (FOB) with use of the Airtraq alone in a manikin study was of great interest to us. They found that in comparison with Airtraq alone, the combined use of the Airtraq and a FOB provided more rapid tracheal intubation in difficult airway scenarios. This finding suggests that a combination of the Airtraq and a FOB may be more effective for managing difficult airways compared with the use of the Airtraq alone. However, there are several aspects of this study that should be clarified. First, the purpose of this study was to evaluate the efficacy of the combined use of the Airtraq and a FOB for tracheal intubation in simulated airway scenarios when the glottic view could not be optimized in the middle of the viewfinder of the Airtraq. However, in the results, the authors did not provide the glottic view obtained by the Airtraq in all airway scenarios. When the tracheal intubation was performed with the Airtraq alone in this study, we would like to know whether the glottis was positioned in the middle of the viewfinder of the Airtraq (i.e., grade 1 view of the Airtraq) with or without optimization maneuvers [2]. In this position, the endotracheal tube (ETT) will be advanced toward the glottis under a predetermined angle, defined by the configuration of the tube conduit and the ETT angulation [3, 4], whereas a partial or total glottic view that is off center, i.e., grade 2 view of the Airtraq, is suboptimal for tracheal intubation with the Airtraq alone [2]. Second, in the results, the authors described that, to successfully intubate the trachea with the Airtraq alone, the requirement for optimization maneuvers increased with the level of difficulty of the tongue edema scenario. However, they did not state what optimization maneuvers were used. On the basis of our accumulated experience with the Airtraq, other than external laryngeal manipulation, adjusting the position of the entire device in the mouth and pharynx is often required to optimize the glottic position before attempting to intubate. Third, three and two participants failed to intubate the trachea with the Airtraq alone in the tongue edema scenarios simulating grade 3 and 4, respectively. In the cervical immobilization scenarios, two and one participants failed with the Airtraq and the combined use, respectively. However, the authors did not provide the reasons for these failed intubations. When the tracheal intubation is performed with the Airtraq alone, our experience suggests that a posterior tube tip location is a most common cause of failed intubation, particularly in patients with tongue edema, micrognathia, short neck, or limited head and neck movement. To solve this issue, the operator can withdraw the Airtraq 1–2 cm away from the glottis and lift the device up [4]; this allows the tube tip to move upward toward the glottis with further advancement after its initial posterior movement [3]. If the larynx is simultaneously pushed down, the posterior tube tip location may often be corrected. Also, the Endoflex ETT with a built-in flexing mechanism and a friction lock is a useful choice to overcome a posterior tube tip location [5]. Fourth, the combined use of the Airtraq and a FOB can enable rapid intubation in managing a difficult airway, but F. S. Xue (&) J. H. Liu Y. J. Yuan X. Liao Department of Anesthesiology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Shi-Jing-Shan District, Beijing 100144, People’s Republic of China e-mail: fruitxue@yahoo.com.cn

Management of unanticipated difficult airway in the prehospital emergency setting.

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