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General Articles: Brief Report

The Pentax-AWS Video-Laryngoscope: The First Experience in One Hundred Patients

Asai, Takashi MD, PhD*; Enomoto, Yoshiro MD; Shimizu, Keiko MD; Shingu, Koh MD*; Okuda, Yasuhisa MD

Author Information
doi: 10.1213/01.ane.0000287647.46165.bc
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The Pentax-AWS (Pentax, Tokyo, Japan) (Fig. 1) is a new video-laryngoscope consisting of a disposable transparent blade (PBLADE®), a 12-cm cable with a charge-coupled device (CCD) camera, and a 2.4-inch liquid crystal device monitor display (Figs. 1 and 2).1–3 The main unit (Fig. 2) is waterproof, facilitating cleaning with water or a disinfectant, such as ethanol. The device is light (290 g without batteries). The image is displayed on a full-color screen. A tracheal tube can be attached to the right side of the blade (Fig. 1). There is a green target symbol on the monitor display, which indicates the direction of the tracheal tube tip. The PBLADE blade has a port through which a suction catheter can be passed. The distal aperture of the suction port is near the CCD camera, so that the tip of the suction catheter will come into view.

Figure 1.
Figure 1.:
Pentax-AWS videolaryngoscope (Pentax, Japan). A tracheal tube is attached to the groove of the PBLADE blade. The tip of the tube should be positioned just beyond the CCD camera.
Figure 2.
Figure 2.:
Main unit of the Pentax-AWS.

The Pentax-AWS has been commercially available in Japan since July 2006, and has been described in a limited number of patients.1–3 The purpose of this study was to evaluate the efficacy of the Pentax-AWS in 100 anesthetized patients.

METHODS

We obtained several Pentax-AWS video-laryngoscopes soon after the devices were licensed for clinical use. We informed patients before anesthesia as to the use of this new device, and told them they could request the use of a conventional laryngoscope if they preferred. Because of ethical concerns, we did not use the device in patients whose airways appeared difficult to manage. In addition, we did not use the device in patients with an ASA physical status of 4 or more, patients with any pathology of the neck or upper respiratory tract, or patients at risk of pulmonary aspiration.

With the approval of our local research ethics committee, we retrospectively collected data from 100 patients who underwent general anesthesia during elective surgery in whom tracheal intubation was indicated. No patients reported previously2,3 were included in this group.

An 8.0-mm ID polyvinylchloride tracheal tube (Portex, Kent, UK) (for males) or a 7.0-mm ID tube (for females) was attached to the groove of the blade, and the tip of the tracheal tube was positioned just beyond the CCD camera (Fig. 3). After induction of anesthesia and neuromuscular blockade, one of three senior anesthesiologists (trained with manikins beforehand) inserted the Pentax-AWS, and advanced the tip of the blade toward the glottic side of the epiglottis, as with the Miller laryngoscope. The position of the device was adjusted so that the glottis was in the center of the green target symbol (Fig. 3), and tracheal intubation was attempted. Time to intubate the trachea, starting from picking up the Pentax-AWS to removal of the scope after successful tracheal intubation was measured. Any problems associated with its use were recorded.

Figure 3.
Figure 3.:
Tracheal intubation using the Airway Scope. The position of the device is adjusted so that the glottis is located in the target symbol, and the tube is advanced into the trachea.

RESULTS

Of 100 patients, 53 patients were males and 47 were females (Table 1). It was possible to insert the blade of the Pentax-AWS and to see a full view of the glottis on the first attempt in 99 of 100 patients. In the remaining patient, insertion of the Pentax-AWS was abandoned because the anesthesiologist judged that it might damage teeth that were already loose. Tracheal intubation was successful in 98 patients (in 96 patients on the first attempt and in 2 patients on the second attempt). In the remaining patient, intubation failed because the tube kept impacting on the arytenoids. The median time for tracheal intubation was 35 s (range, 5–120 s). The only equipment malfunction was tracheal tube dislodgement from the blade during an attempt at intubation (with a successful intubation). There was no damage to teeth, bleeding from the oropharynx, or hypoxia.

Table 1
Table 1:
Patients’ Characteristics (Mean (sd) [Range])

DISCUSSION

It was generally easy to insert the Pentax-AWS, to obtain a full view of the glottis, and to intubate the trachea, without major complications. Previous video-laryngoscopes have suffered from difficulty in advancing the tracheal tube into the trachea because the glottis was not under direct view, requiring frequent need to adjust the shape of the tracheal tube with a stylet.4,5 In contrast, with the Pentax-AWS, a tracheal tube can be attached to the side of the blade, and the tip of the tube is already shown on the monitor display. In our patients, once the glottis was positioned in the target symbol, it was easy to advance the tube into the trachea in 98 of 99 patients.

The Pentax-AWS may be difficult to use in patients with limited mouth opening because the maximum width of the blade is approximately 2.5 cm. Another possible disadvantage is that there is a theoretical risk of blurred images by fogging. Nevertheless, in our patients, this was rare. The manufacturer suggests that fogging is infrequent, because the CCD camera will not be exposed to humid air in the oropharynx, and because the blade is slightly warmed by the camera light. Lastly, the single-use blade costs 2500 yen or approximately 20 dollars, and thus its routine use may be restricted. There have been several reports of successful use of video-laryngoscopes in patients with difficult airways.5–7 If the Pentax-AWS is effective in patients with difficult airways, this expenditure may be justifiable.

REFERENCES

1. Koyama J, Aoyama T, Kusano Y, Seguchi T, Kawagishi K, Iwashita T, Okamoto K, Okudera H, Takasuna H, Hongo K. Description and first clinical application of AirWay Scope for tracheal intubation. J Neurosurg Anesthesiol 2006;18:247–50
2. Asai T, Yoshihiro Enomoto, Yasuhisa Okuda. Air way scope, a portable videolaryngoscope, for confirmation of tracheal intubation. Resuscitation 2007;72:335–6
3. Asai T, Enomoto Y, Okuda Y. Airway scope for difficult intubation. Anaesthesia 2007;62:199
4. Doyle DJ, Zura A, Cooper RM. Videolaryngoscopy in the management of the difficult airway. Can J Anaesth 2004;51:95
5. Matsumoto S, Asai T, Shingu K. TruViewEVO2 videolaryngoscope. Masui (Jap J Anesth) 2007;56:213–7
6. Cooper RM. Use of a new videolaryngoscope (GlideScope) in the management of a difficult airway. Can J Anaesth 2003;50:611–3
7. Asai T, Shingu K. Use of the videolaryngoscope. Anaesthesia 2004;59:513–4
© 2008 International Anesthesia Research Society