Tracheal intubation with LMA CTrach™: need for cricoid pressure

Abstract

Editor—Before replacing the intubating laryngeal mask airway (ILMA) with the LMA CTrach™ (CT) in our predefined algorithm for unexpected difficult airway management,1Combes X Sauvat S Leroux B et al.Intubating laryngeal mask airway in morbidly obese and lean patients: a comparative study.Anesthesiology. 2005; 102: 1106-1109Crossref PubMed Scopus (69) Google Scholar we assessed CT performance in morbidly obese patients and some with an anticipated difficult airway. We observed that cricoid pressure can be helpful when using the CT. We report two cases of patients with a difficult airway, who despite the CT being optimally placed in the pharynx, required a combination of a Chandy manoeuvre and external force directly applied over the cricoid cartilage to facilitate tracheal intubation. A difficult airway was anticipated in the first patient because of a previous laryngeal tumour (the patient refused awake fibreoptic intubation) and in the second patient upper airway examination revealed a Mallampati grade 3 and 4.0 and 6.5 cm inter-incisive and thyromental distances, respectively. After preoxygenation, anaesthesia was induced with propofol and sufentanil followed by succinylcholine after Guedel cannula-assisted difficult facemask ventilation had been established. For the first patient, a size 5 CT was placed as second step after failed direct laryngoscopy (Cormack and Lehane grade 4) tracheal intubation and a size 4 CT was used as first step for the second patient. In both cases, ventilation through the mask was rapidly optimized using Chandy manoeuvre. After the viewer was attached, the laryngeal view showed asymmetrically shaped aryepiglottic folds placed in upper position of the screen with an open glottis partially visible just above in the first case, and prominent bulky aryepiglottic folds centred in the first plane with glottis aperture visible behind in the second patient. For both patients, first and second tracheal intubation attempts failed, but adjusted external pressure directed posteriorly over the cricoid cartilage by an assistant while a Chandy manoeuvre was maintained, resulted in better laryngeal view with the aryepiglottic folds pulled down and glottis exposition optimized. This procedure enabled the LMA™ designed reusable cuffed tube simply entering the glottis under control of the view. Two studies have assessed the specific effects of cricoid pressure applied with ILMA.3Asai T Barclay K McBeth C Vaugahan RS Cricoid pressure applied after placement of the laryngeal mask prevents gastric insufflation but inhibits ventilation.Br J Anaesth. 1996; 51: 389-390Crossref Scopus (18) Google Scholar 4Asai T Murano K Shingu K Cricoid pressure applied after placement of laryngeal mask impedes subsequent fibreoptic intubation through mask.Br J Anaesth. 2000; 85: 256-261Crossref PubMed Scopus (25) Google Scholar The authors demonstrated that insertion and tracheal intubation were impeded, but tracheal intubation was more often successful if cricoid pressure was applied after ILMA insertion. Moreover, fibreoptic studies demonstrated that cricoid pressure affected the laryngeal view obtained through the laryngeal mask.4Asai T Murano K Shingu K Cricoid pressure applied after placement of laryngeal mask impedes subsequent fibreoptic intubation through mask.Br J Anaesth. 2000; 85: 256-261Crossref PubMed Scopus (25) Google Scholar 5Asai T Use of laryngeal mask for tracheal intubation in patients at increased risk of aspiration of gastric content.Anesthesiology. 1992; 77: 1029-1030Crossref PubMed Scopus (29) Google Scholar We have used this property of cricoid pressure to our advantage to modify the position of the laryngeal structures. In our two cases, the viewer allowed adjustment of cricoid pressure for better alignment of the glottis and the tube resulting in successful tracheal intubation. Although we did not measure the force we applied on the anterior neck, an assistant felt that this was similar to the force used normally for cricoid pressure. In the first 100 patients in whom we used CT in our department, six required more than one attempt at intubation and two of them required external laryngeal pressure. In conclusion, adjusted external force applied posteriorly to the cricoid by an assistant can improve the view of the larynx through the LMA CTrach™ and facilitate tracheal intubation.