We read with great interest work regarding blind intubation through Air-Q SP laryngeal mask in children.1 We would like to share our experience with blind intubation through the Air-Q SP laryngeal mask in a totally different group of patients, that is the morbidly obese. We conducted an observational study with 33 morbidly obese patients (BMI > 40 kg m−2) scheduled for elective bariatric surgery (Ethics Committee Medical University of Lodz, N° RNN 363/15/KB, date of approval 21 May 2015). Our hypothesis was that Air-Q SP mask may be used in unexpected difficult intubation in morbidly obese patients for oxygenation and blind intubation. We evaluated the Mallampati score and neck circumflex in all patients. The following with suspected difficult intubation were excluded from our observations: neck circumflexion more than 42 cm2, Mallampati above 3, reduced mouth opening or neck mobility. Anaesthesia was conducted following the recommendations of the European Society for Peri-Operative Care of Obese patient (ESPCOP, http://www.espcop.org). After positioning the patients in the head elevated laryngoscopy position (HELP) and preoxygenation, general anaesthesia was induced with propofol 300 mg intravenously. After ensuring facemask ventilation, the patients received rocuronium 0.6 mg kg−1 ideal body weight intravenously. When the train-of-four stimulation reached zero response, an Air-Q SP laryngeal mask was inserted. We were using numbers 3.5 or 4.5 laryngeal masks depending on the patient's ideal body weight. Residents of anaesthesiology were asked to insert the laryngeal mask. All were trained in laryngeal mask insertion and had adequate experience. After successful mask insertion, we ensured possible ventilation (adequate tidal volume) and evaluated leak pressure listening to the leak of air around the mask while using a fresh gas flow of 3 l min−1 and increasing the valve pressure. Then blind intubation was performed after proper lubrication of the ventilation channel of the laryngeal mask. Endotracheal tube sizes 7 and 7.5 were inserted with laryngeal masks sizes 3.5 and 4.5, respectively. One attempt at tracheal tube insertion was performed. Successful intubation was confirmed with EtCO2. If intubation was not possible, the laryngeal mask was removed and standard intubation using a Macintosh blade laryngoscope was performed. If intubation through the laryngeal mask was successful, the laryngeal mask was removed keeping the endotracheal tube in position using the tube exchange stylet for Air-Q masks. After removing the laryngeal mask, potential injuries were evaluated by checking for blood on the laryngeal mask. Results of our observation are presented in Table 1. Overall success ratio for Air-Q SP insertion was 87.9%. Success ratio of blind intubation through the Air-Q SP was only 24.2%. There was no correlation between successful blind intubation and measured parameters such as BMI or Mallampati score. Blood was recorded on 12.1% of laryngeal masks.
Morbid obesity may be associated with difficult mask ventilation and difficult intubation. Therefore, devices that may be useful in cases of unexpected difficulties with airway management in this group of patients should be evaluated.2 There are several supraglottic airway devices designed for blind intubation, for example the intubating laryngeal mask airway (ILMA), Cobra PLA or I-Gel. Comparing with other supraglottic airway devices designed for blind intubation, the success rate achieved with the Air-Q SP laryngeal mask was low. However, there are only a few other studies on blind intubation through supraglottic airway devices in morbidly obese patients. Combes et al.3 evaluated the ILMA in morbidly obese patients and reported a very high success ratio (96%). Arslan et al.4 reported a 97% success rate at first attempt in morbidly obese patients using the ILMA. Frappier et al.5 studied 118 morbidly obese patients and showed that the ILMA was an effective airway device for ventilation and intubation in these patients. The Air-Q laryngeal mask differs from the ILMA, therefore it is difficult to compare the results of these studies with ours.
In conclusion, we suggest that the Air-Q SP laryngeal mask is effective for temporary ventilation in morbidly obese patients, but we do not recommend it for blind intubation.
Acknowledgements related to the article
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1. Kleine-Brueggeney M, Nicolet A, Nabecker S, et al. Blind intubation of anaesthetised children with supraglottic airway devices AmbuAura-i and Air-Q cannot be recommended: A randomised controlled trial. Eur J Anaesthesiol
2. Gaszynski T. Clinical experience with the C-Mac videolaryngoscope in morbidly obese patients. Anaesthesiol Intensive Ther
3. Combes X, Sauvat S, Leroux B, et al. Intubating laryngeal mask airway in morbidly obese and lean patients: a comparative study. Anesthesiology
4. Arslan ZI, Ozdamar D, Yildiz TS, et al. Tracheal intubation in morbidly obese patients: a comparison of the Intubating Laryngeal Mask Airway and Laryngeal Mask Airway CTrach. Anaesthesia
5. Frappier J, Guenoun T, Journois D, et al. Airway management using the intubating laryngeal mask airway for the morbidly obese patient. Anesth Analg