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Correspondence  |   June 2001
Acromegaly, the Mallampati, and Difficult Intubation
Author Affiliations & Notes
  • Hubert Schmitt, M.D.
    *
  • *Friedrich-Alexander University, Erlangen, Germany. hubert.schmitt@kfa.imed.uni-erlangen.de
Article Information
Correspondence
Correspondence   |   June 2001
Acromegaly, the Mallampati, and Difficult Intubation
Anesthesiology 6 2001, Vol.94, 1150. doi:
Anesthesiology 6 2001, Vol.94, 1150. doi:
In Reply:—
We appreciate Dr. Calder’s interest and his comments and are grateful for the opportunity to reply. First, regarding original Mallampati scoring, we agree with Dr. Calder that there are some problems in assessing reliably and reproducibly pharyngeal structures. There is indeed a considerable interobserver variability in performing the modified Mallampati test. 1 We used the modified test (performed by one investigator) because this enabled us to distinguish patients as class IV who had a very large tongue, concealing most of the oral cavum, a typical acromegalic feature. Moreover, this class has been shown to have the best reproducibility. 2 
Second, regarding likelihood ratio and predictive power of the Mallampati test, first, we have to apologize for an error in the Results. The sensitivity of the Mallampati test was 76%, and the specificity was 44% (page 112, line 36; the terms are interchanged). 3 We do agree with Dr. Calder that the likelihood ratio for a positive test result is easily to interpret and therefore should be cited more frequently. Because of its limited use in the literature, we did not refer to it. The likelihood ratio for a positive Mallampati test in our study was 1.4. This is a poor value and confirms other publications reporting a poor predictive value of the Mallampati test as the only preoperative screening test. However, the Mallampati test is recommended as one of several tests (thyromental distance, head and neck mobility, jaw movement) that are useful for preoperative airway evaluation. 4,5 In contrast to this poor overall predictive value, Mallampati class IV yielded a specificity of 0.97 and a likelihood ratio of 9.6 (95% CI; 3.0–30.8) in predicting a difficult laryngoscopy in our study. This is important because a special patient with this sign has a higher risk of a difficult airway compared with one without, and we think this is helpful information to the anesthetist. Of course, this high specificity is at the expense of the sensitivity, but there are, as Dr. Calder mentioned, many factors influencing Mallampati sign and performance of intubation. We agree that head and neck mobility may influence the visibility of pharyngeal structures, 6 but from our data, an association between head and neck mobility and Mallampati class cannot be deduced. We are convinced that soft tissue, anatomical shape of the mandible, and the function of the temporomandibular joint are important, too. There are special tests that assess these factors better than the Mallampati test does. 4 
References
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