We read the original article by Kamalipour and colleagues with great interest . Prediction of difficult intubation cases with 100% sensitivity is the ultimate goal of all the anaesthesiologists and so far the data presented in this article seems to provide quite objective criteria. We have previously performed a clinical and anatomical analysis of the measurements (thyromental, hyomental, sternomental distances) in 334 patients and 12 cadavers . The goal of our study was to determine whether these parameters were affected by age and gender. In this study we have shown that hyomental distance was the only variable not influenced by age and gender . Kamalipour and colleagues stated that 64 male and 36 female, aged 18–89 were enroled in their study. However, no descriptive data concerning the distribution of age groups were given and statistical comparison between age, gender and study parameters were not presented. Since thyromental and sternomental distances are prone to be affected by age and gender it would be wise to analyse the data and provide additional information on the impact of these factors.
Kamalipour and colleagues stated that the radiation risk is negligible as the radiation dose of a lateral neck X-ray is far below then the safe dose per year. However, the authors also stated that this technique is ‘had no monetary cost’. At University Hospitals in Turkey the cost of a lateral neck X-ray is 6.3 New Turkish Lira (approximately US $5). Although this cost may be considered as a very low or negligible, it will bring an additional cost in large scale hospitals if used as a screening test. We believe that it is wise to use this non-invasive technique in patients prone to difficult intubation such as patients with higher Mallampati Classes (III–IV).
The patient population in the study of Kamalipour and colleagues was only 100 patients. The limited number of patients enroled to the study questions the power of the study. Besides, in Table 1 it is obvious that there were only four patients with Mallampati Classes III and IV. Four patients are inadequate to discuss or even reach a conclusion about the results of this study. Therefore, the results of this study can not be use to cover the patient population with Mallampati Classes III and IV. Further investigation on patients with Mallampati Classes III and IV is needed to evaluate the relation between the study parameters and difficult intubation.
In conclusion, we believe that authors should address the effects of age and gender on study parameters and comment on the power of the study.
1. Kamalipour H, Bagheri M, Kamali K et al
. Lateral neck radiography for prediction of difficult orotracheal intubation. Eur J Anaesth
© 2006 European Society of Anaesthesiology
2. Türkan S, Ates Y, Cuhruk H, Tekdemir I. Should we reevaluate the variables for predicting the difficult airway in anaesthesiology? Anesth Analg