Anesth Analg 2003;96:911
© 2003 International Anesthesia Research Society
LETTERS TO THE EDITOR
Class Zero Airway and Laryngoscopy
V. K. Grover, MD MNAMS,
Rajesh Mahajan, MD, and
Monish Tomar, MD
Departments of Anaesthesia and Intensive Care, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
To the Editor:
Recent observations by Ezri et al. (1) and Meleck et al. (2) emphasized the class zero pharyngoscopic view, wherein the tip and posterior aspect of the epiglottis can be visualized on mouth opening and protrusion of the tongue. We made a similar observation in a 52-yr-old woman weighing 56 kg who presented for pansinusectomy. Airway assessment with the patient in a sitting position, mouth fully opened, tongue fully protruded, and without phonation revealed class zero airway (Fig. 1). After induction of anesthesia and 4 min after the administration of vecuronium 6 mg, laryngoscopy was performed with Mackintosh No. 3 blade in sniffing position. Only a large floppy epiglottis could be seen, which corresponded to Cormack and Lehane Grade 3 laryngoscopy. Attempts to visualize the glottis despite good relaxation, forward traction on the laryngoscope, and manipulation of the larynx failed to improve the view. Use of Mackintosh No. 4 blade followed by leverage with McCoy blade could barely bring arytenoids and posterior part of the vocal cords into view. Thereafter, a gum elastic bougie was negotiated into the glottic aperture and tracheal tube was railroaded over it, and tracheal intubation was achieved.
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Figure 1. Photograph during airway assessment with the patient in a sitting position with mouth fully opened and tongue fully protruded.
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Ezri et al. (3) found the incidence of class zero airway to be 1.18% and found it to be an excellent predictor of Grade I laryngoscopy. All patients in their study with grade zero airway were females in the age range of 19 to 38 years. Although our patient was 54 years old, she did not have any osteoarthritic changes or abnormal dentition that could have led to difficult laryngoscopy. The cause of difficult laryngoscopy in our patient could be explained by the anatomical fact that epiglottis was large enough to overhang the tongue as seen on preoperative airway examination and restricting the view of laryngeal inlet once the patient was paralyzed and under anesthesia. Postoperatively indirect laryngoscopy (IDL) depicted the same findings. Hence, it would be advisable preoperatively to perform IDL in such class zero airway patients to have an idea about anatomy of epiglottis and to be prepared beforehand to deal with this sentinel lamellae if it hinders the laryngoscopic view and intubation.
References
- Ezri T, Cohen I, Geva D, Szmuk P. Pharyngoscopic views [letter]. Anesth Analg 1998; 87: 748.
- Maleck WH, Koetter KK, Less SD. Pharyngoscopic views [letter]. Anesth Analg 1999; 89: 256–7.[Free Full Text]
- Ezri T, Warters D, 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.[Abstract/Free Full Text]
