Anesth Analg 2003;97:1199
© 2003 International Anesthesia Research Society
LETTERS TO THE EDITOR
Alas, Too Big a Bite!
Prabhat Tewari, MD
Department of Anaesthesiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India
To the Editor:
I read with interest article regarding the upper lip bite test (ULBT) (1), but certain clarifications are required.
The authors have compared Mallampati with ULBT. They have also stated that ULBT actually tests mandibular subluxation and buckteeth at once. Therefore, comparison of two ways to assess difficulty during tracheal intubation because of three different causes does not make much sense, and the result reached gives no insight. During ULBT one finds the reflex movement of the upper lip in the reverse direction over the teeth inside the mouth opening. This movement may definitely alter the point of meeting of vermilion line with the lower incisors. It might be different in different age groups and also in males and females. In the same individual, this may also vary according to the effort applied. There is also a chance of injuring the lips with the teeth.
Opening mouth widely shows buckteeth, the mandibular movement (as happens during laryngoscopy), and also shows space inside the oral cavity. This space is essential for laryngoscopy and intubation.
I think this simple maneuver provides more information than biting the lips.
Reference
- Khan ZH, Kashfi A, Ebrahimkhani E. A comparison of the upper lip bite test (a simple new technique) with modified Mallampati classification in predicting difficulty in endotracheal intubation: a prospective blinded study. Anesth Analg 2003; 96: 595–9.[Abstract/Free Full Text]
Response
Zahid Hussain Khan, MD, and
Arash Kashfi, MD
Department of Anesthesiology/Neurosurgery, Imam Khomeini Hospital, Tehran, Iran
In Response:
We appreciate the comments to our article by Dr. Tewari.
While our technique, the upper lip bite test (ULBT), simultaneously evaluates mandibular subluxation and buckteeth, there undoubtedly exists a strong correlation between the ULBT and the airway anatomical architecture, reinforcing ULBT’s strength and efficacy of not only predicting the airway class and the structures behind the closed curtain, but also its extraordinary potential of not having caused even a single case of lip injury in thousands of patients being tested by our friends and colleagues everywhere. The ill-conceived notion that the ULBT might cause injury to the lips is thus not only ill founded but sheer guesswork and a generalization not supported by scientific backing and statistical layout.
We are aware that the upper lip moves erratically in the opposite direction over the teeth inside the mouth opening, but this movement is noticed and in fact testifies and unequivocally declares and upholds the movements of the mandibular joint and the structures of the larynx and thus in no way hinders or obstructs our classification wherein we have assigned a pivotal role to the vermilion line.
Moreover, although widely opening the mouth shows buckteeth, the mandibular movement, and the space inside the oral cavity, this maneuver to which Dr. Tewari refers as simple in no way provides one with an easy bedside assessment of mandibular subluxation, which of course is adequately and fully addressed in ULBT.
While performing the ULBT, an effort is in no way banned or barred. We, on the other hand, encourage our patients to get as far a bite of the upper lip as possible by employing all their resources and strength in terms of taking a prolonged inspiratory effort through a tight aperture between the overriding lower incisors and the upper lip. This effort significantly alters their ability to go beyond the vermilion line zone and that is in fact our cherished goal and in no way does it hinder the process but rather facilitates and affords a meaningful strength to the ULBT.
There is no doubt that difficult intubation is a multifactorial problem, and thus logically a good test should be able to disclose it swiftly with a gentle and acceptable maneuver.
Finally, we vehemently state that the ULBT has the inherent quality to unveil and unravel the hidden airway anatomy and the potential laryngoscopic difficulties while the mouth remains closed, an achievement that remains unmatched and unparalleled.
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