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

Abstract

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.