視像輔助氣道處理 : 香港一所急症室的經驗

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1 Hong Kong Journal of Emergency Medicine Video-assisted airway management: experience in a Hong Kong emergency department 視像輔助氣道處理 : 香港一所急症室的經驗 WCY Hung 熊忠勇, KL Tsui 徐國樑, HH Yau 游漢雄, CW Kam 甘澤華 Video-assisted airway management is a new concept for monitoring and managing both normal and difficult tracheal intubations, with the aid of video-transmission of the view from the tip of intubating devices such as stylets or intubating laryngoscopes. Its principle, practical application and local experience are illustrated by some sample cases and its future development is discussed. (Hong Kong j.emerg.med. 2007;14:89-93) 視像輔助氣道處理是監察及處理一般及困難氣管插管的新概念, 用視像幫助由插管儀器如管心探子或插管喉鏡的未端傳送影像 本文以幾個樣本個案舉例說明其原理, 實際應用及本地的經驗, 並討論其將來的發展 Keywords: Fiber optics, intratracheal intubation, laryngoscopes 關鍵詞 : 光學纖維 氣管內插管 喉鏡 Case 1 An elderly male, with history of nasopharyngeal carcinoma with radiotherapy done, was brought to our emergency depar tment ( ED) in July 2006 by ambulance after being found unconscious at home. On arrival, he was in cardiac arrest. Immediate resuscitation was performed. During intubation, the patient's jaw and neck were found to be so stiff that traditional intubation using direct laryngoscope (DL) and bougie were both unsuccessful. As a "Plan C" strategy (Figure 1), video-assisted airway management (VAAM) with a Seeing Optical Stylet (SOS) was used (Figure 2). It has adjustable curvature at the distal end, ranging from 15 degree to 60 degree, and enables direct visual image of the tip of the endotracheal tube (ETT). An endotracheal tube was inserted and advanced under endoscopic visual control until the vocal cords were visualised. The distal end of the endotracheal tube was then passed between the vocal cords and the patient was successfully intubated (Figure 3). Correspondence to: Hung Chung Yung, William, FRCSEd, FHKAM(Emergency Medicine) Tuen Mun Hospital, Accident & Emergency Department, Tsing Chung Koon Road, Tuen Mun, N.T., Hong Kong hcy395@yahoo.com.hk Tsui Kwok Leung, FRCSEd, FHKAM(Emergency Medicine) Yau Hon Hung, FRCSEd, FHKAM(Emergency Medicine) Kam Chak Wah, FRCSEd, FHKAM(Emergency Medicine) Figure 1. Contingency plan for difficult airway management (A&E Department, Tuen Mun Hospital).

2 90 Hong Kong j. emerg. med. Vol. 14(2) Apr 2007 Figure 2. Video-assisted airway management in action. revealed the positive "thumb sign". Ear-nose-throat (ENT) surgeon was immediately consulted for suspected acute epiglottitis according to the department's protocol as well as the Accident & Emergency Coordinating Committee's guideline. Prior to the arrival of the ENT surgeon, a senior emergency physician with VAAM experience used a fibreoptic laryngoscope attached to a video unit to examine the pharynx. A swollen supraglottis was found and the image was recorded (Figure 4). The ENT surgeon who arrived 20 minutes later confirmed with the image as acute supraglottitis. Case 4 Figure 3. Confirmation of successful intubation by direct visualisation. ET=endotracheal. An old age home resident was brought to our ED in August 2006 for sudden collapse while having lunch. After tracheal intubation, a fibreoptic bronchoscope connecting to a video unit was inserted through the endotracheal tube. Both bronchi were found to be loaded with rice and vegetables (Figure 5). The diagnosis of aspiration was confirmed, compatible with the history provided by the old age home staff. Case 2 A pedestrian was brought in by ambulance in July 2006 after being knocked down by a bus. As the patient was suspected to be suffering from cervical spine injury, he was being immobilised by a neck collar, head blocks and a long spinal board. Upon arrival, he was found to be in comatose state. Immediate intubation was necessary to secure the airway before CT examination, which was expected to be difficult as no head-tilt manoeuvre in this patient would be allowed. The videoassisted airway management approach was adopted. With the help of a SOS, the endotracheal tube was easily inserted and advanced under direct vision with minimal movement of the jaw and neck. The patient was successfully intubated and his airway secured. Figure 4. Acute supraglottitis. Case 3 A male adult presented to our ED in September 2006 with severe throat pain. Lateral X-ray view of the neck Figure 5. Bronchoscope-aided diagnosis of aspiration. ET=endotracheal.

3 Hung et al./video-assisted airway management 91 Case 5 In December 2006, a male patient presenting with cardiac arrest at home was successfully intubated in the resuscitation room. While ventilating with the ventilator, sounds of leakage were heard through the patient's mouth. However, the endotracheal tube's cuff was found to be intact through pre-insertion trial and visual pressure confirmation of the pilot balloon. Finally, the source of leakage was found by means of direct observation of the pharynx using a SOS connecting to the video unit, in which the endotracheal tube's balloon was found to be protruding from the vocal cord (Figure 6). Under video monitoring through the VAAM, the balloon was deflated and the endotracheal tube was re-adjusted with the balloon in proper position. Discussion Video-assisted airway management, a term first quoted by Markus Weiss in 1999, 1 is a new concept for managing unexpected difficult tracheal intubations. 2 Complication s arising from difficu lt tracheal intubations, especially oesophageal intubation, have been the major causes for anaesthesia- related morbidities and mortalities, either in the operating theatre or in the resuscitation room of an ED. Although pulse oximetry and capnometry monitoring had been vigorous ly emp loyed, su bst ant ial nu mbers of oesophageal intubation were still missed. In USA, claims related to complications of difficult or Figure 6. Endotracheal tube cuff protruding through vocal cord. oesophageal intubation accounted for up to 6%. 1 As a result, new and better techniques for intubation have been invented and one of them is VAAM. VAAM refers to airway management with the aid of video-transmission of the view from the tip of intubating devices through an ultrathin fibreoptic cable to a bedside video-monitoring unit. This allows the physician to "visually" monitor the intubation procedure, to confirm the endotracheal tube position and to guide the ETT during difficult intubation. The standard equipment set consists of a visual device, either a Visual Optical Intubation Stylet (VOIS) or a Visual Intubating Laryngoscope (VIL) together with the bedside video monitoring system for real-time monitoring of images. 3-6 Various VOIS have been designed and most of them have a stylet with integrated optical fibre for both image and light together as well as an air channel for lens protection. VIL is similar to a conventional intubation laryngoscope but with a guide bore hole for insertion of an ultrathin video-endoscope which leads from the tip through the blade to the bottom of the handle. In some models, the videoendoscope inserted into the laryngoscope can leave the device with a 2-metre long cable for connection to the video-imaging unit. 4 Our experience Since 2005, Tuen Mun Hospital Accident and Emergency Department has introduced the use of VAAM. We agree so far that it is a useful concept in many clinical situations. Our VAAM unit composes of a VOIS called Seeing Optical Stylet (SOS) (Figure 7), a VIL called Bullard laryngoscope (Figure 8), a bedside video monitoring unit (APPLItec MSV-2000 medical video camera, a 17-inch LCD monitor) (Figure 9) and a video-recording unit (ARCHOS AV500 Mobile Digital Video Recorder/Portable Media Player [PMP]) (Figure 10). The video-recording unit is an absolutely important component of the system so that interesting images can be captured for archive, review, learning and teaching. We prefer to use PMP rather than the conventionally used video tape recorder or DVD recorder because PMP has numerous advantages in terms of smaller size, better internal power supply, easy to start up and readily compatible computer storage format.

4 92 Hong Kong j. emerg. med. Vol. 14(2) Apr 2007 Figure 7. Seeing Optical Stylet (SOS). Figure 8. Bullard laryngoscope. Figure 9. Medical video camera and a 17-inch LCD monitor. Figure 10. Mobile digital video recorder. SOS can be an invaluable adjunct to the traditional direct laryngoscopic instrument with or without the use of stylet even in uncomplicated ETT insertion procedure. After controlling the tongue, lifting the epiglottis with the direct laryngoscope, SOS will allow us to bend the ETT to the desired curvature (up to 60 degrees) to fit the angle of entry and at the same time to see the ETT advancement under visual control. In case of unexpectedly difficult DL, the physician may not be able to see the vocal cord through the mouth even in the best direct laryngoscopic view or position because of a stiff jaw, a small mandible or a large tongue in Mallampati Class 4. The undesirable 'blind intubation' scenario could be prevented by VAAM. By inserting the ETT loaded with SOS, the physician will not be 'blinded' anymore and can actually 'see' the 'most obscured' vocal cords and the whole intubation procedure will be smoother. In situations where manipulation of the neck and head posture or lifting of jaw would be contraindicated e.g. fractured mandible, SOS could be particularly useful as illustrated in case 2 reported above. VAAM-aided endotracheal intubations usually serve as a "Plan C" strategy (i.e. failed conventional direct laryngoscopic intubation and bougie) in our department (Figure 1) and should be performed only by colleagues with prior training. From previous studies, VAAM has not been found to be associated with patient complications. Potential complications are the same as those of orotracheal intubation with flexible fiberscopes (e.g., oropharyngeal trauma, arytenoid subluxation, vocal cord injury). 4 In our experience, most colleagues could acquire the skills of VAAM through short lectures conducted on the training day plus one to two hands-on tutorials with practice on a manikin. Initial applications on real patient should be super v ised by exp erienced p hysicians. In our department, videos of interesting images and relevant articles have been posted on the department's intranet for self learning which is very helpful for the juniors to achieve clinical maturity and expertise. The unit can also be equipped with other fibreoptic endoscopes like laryngoscope or bronchoscope for more advanced airway management. The benefits in aiding

5 Hung et al./video-assisted airway management 93 diagnosis like acute epiglottitis and aspiration are well illustrated by case 3 and case 4 reported above. Future research in VAAM should include clinical studies to compare this new intubation technique with other conventional methods in terms of simplicity, efficacy and reduction of complications especially oesophageal intubation. Another possible area of research will be on infection prevention. By adopting VAAM technique, the physician no longer needs to lean over the patient's head to the proximity of only a few inches during intubation. The distance between the two parties can be significantly increased. Studies on possible value or impact on prevention of dropletspread infections during 'hazardous' intubation procedures may be promising. Conclusion VAAM represents a new generation of intubation monitoring and is an excellent tool for demonstration, teaching, supervision and documentation. Videoassisted tracheal intubation is almost the same procedure as traditional intubation. Only in the last step, the ETT is guided by the video-view. This makes the technique potentially superior for difficult intubation management. Looking at a video-display in critical circumstances is much more comfortable than looking into a viewfinder of an endoscopic device, because the operator can remain in upright position and can easily change the view from the oropharynx to the monitor and vice versa. This enables nearly simultaneous observation of the video-display, patient and monitors. Furthermore, it provides a display for multiple viewers for real-time teaching. Images or videos captured by the recording system will be useful for subsequent archive and review. 1 On the other hand, digital images or clips can be sent to relevant specialists via electronic means for immediate professional comment and input. Again, it exemplifies the fascinating possibilities in the new era of tele-medicine. Last of all, adopting VAAM technique may reduce risk of infection by droplet spread during intubation procedures. References 1. Weiss M. Video-assisted airway management. The Internet Journal of Anesthesiology 1999;3(1). [cited 2006 Sep 17]. Available from: journals/ija/vol3n1/vaam.htm 2. Frass M, Kofler J, Thalhammer F, Staudinger T, Dielacher C, Krafft P, et al. Clinical evaluation of a new visualized endotracheal tube ( VETT). Anesthesiology 1997;87(5): Weiss M, Schwarz U, Gerber AC. Difficult airway management: comparison of the Bullard laryngoscope with the video-optical intubation stylet. Can J Anaesth 2000;47: Weiss M. Video-intuboscopy: a new aid to routine and difficult tracheal intubation. Br J Anaesth 1998;80(4): Gravenstein D, Melker RJ, Lampotang S. Clinical assessment of a plastic optical fiber stylet for human tracheal intubation. Anesthesiology 1999;91(3): Biro P, Weiss M, Gerber A, Pasch T. Comparison of a new video-optical intubation stylet versus the conventional malleable stylet in simulated difficult tracheal intubation. Anaesthesia 2000;55(9):886-9.