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Correspondence |
Post Graduate Intstitute of Medical Education and Research, Chandigarh, India, E-mail: drmahajanr{at}rediffmail.com
To the Editor:
The recent correspondence by Sakuragi et al. describing tracheal intubation in an adult male with a Mallampati class zero airway was of interest to us.1 Although it was correctly identified that Ezri et al. failed to identify any adult men with a Mallampati class zero airway in a series of 764 patients,2 two such cases have been reported previously.3,4
We, too, have encountered patients with a class zero airway. The first patient was a 48-yr-old male whose epiglottis was visible on mouth opening and tongue protrusion. Ventilation was easily managed following induction of general anesthesia. Cormack and Lehane laryngoscopy was grade 1, and he was easily intubated.3 However, the experience from a limited number of cases does not imply that a Mallampati class zero airway will predict easy intubation, as suggested by Sakuragi et al.1 We have also reported a difficult grade 3 laryngoscopy in a 52-yr-female with Mallampati class zero airway, due to a large obstructive epiglottis.5 However, we did not encounter difficulty in mask ventilation in this patient. In contrast, in a 69-yr-old male patient with a Mallampati class zero airway, Fang and Norris reported extreme difficulty in mask ventilation, in addition to difficult intubation with a laryngoscopic view grade 3.4 It is possible that a large redundant epiglottis acts as a flap, blocking the glottic opening every time positive pressure is applied to ventilate the patient. Further, a large epiglottis may overhang the tongue as seen on preoperative airway examination, and restrict the view of laryngeal inlet once the patient is paralyzed under anesthesia.5
At present, we observe that patients with a class zero airway may belong to any age group. We have undertaken a study to determine the incidence of Mallampati class zero airway, and its possible correlation with age, sex, body mass index, and other factors.5 Until the results of this trial are available, we suggest that all patients with class zero airway should be subject to indirect laryngoscopy to check whether the epiglottis hinders the laryngoscopic view. Furthermore, the ability to ventilate such patients with a facemask must be confirmed before administration of a neuromuscular blocking drug.3,5 In conclusion, we disagree with Sakuragi et al. that a class zero airway should necessarily predict easy tracheal intubation, and that one should, in fact, be prepared with the "difficult intubation drill" when presented with such a patient.
References
1 Sakuragi T, Hori K, Shiratake T, Miyawaki J, Ishida M. Tracheal intubation in a adult male with Mallampati class zero airway. Can J Anesth 2005; 52: 115–6.
2 Ezri T, Warters RD, Szmuk P, et al. The incidence of class zero airway and the impact of Mallampati score, age, sex, and body mass index on prediction of laryngoscopy grade. Anesth Analg 2001; 93: 1073–5.
3 Grover VK, Mahajan R. Class zero airway and laryngoscopy. Anesth Analg 2004; 98: 870–1.
4 Fang B, Norris J. Class zero airway and laryngoscopy. Anesth Analg 2004; 98: 870–1.
5 Grover VK, Mahajan R, Tomer M. Class zero airway and laryngoscopy. Anesth Analg 2003; 96: 911.
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