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Correspondence

Lateral neck radiography

Kamalipour, H.*; Yarmohammadi, H.*

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European Journal of Anaesthesiology: April 2006 - Volume 23 - Issue 4 - p 353-354
doi: 10.1017/S0265021506230588

Reply

EDITOR:

We appreciate the comments on our original article. Drs Ates and Alanoglu have raised 3 questions. The first question relates to descriptive data concerning the distribution of age groups and statistical comparison between age, gender and study parameters. These data were analysed in our patients, however there were no statistically significant differences between them [1].

The second question concerns the number of the patients in the study (100 patients) and the low incidence of patients with difficult intubation. As was noted in the article’s introduction, the incidence of difficult intubation in surgical patients undergoing general anaesthesia is approximately 1–18% [2]. Accordingly, the minimum sample size was estimated using an a priori power analysis based on a confidence level of 0.95 and a power of 0.90. Therefore, the power of the study is statistically valid. In our study the incidence of difficult intubation was 15% (15 out of 100 patients), which was statistically sufficient [1]. Similar studies in which various clinical, skeletal (lateral X-rays) and soft tissue (three-dimensional computed tomography imaging or magnetic resonance imaging) measurements were used to predict difficult intubation, used similar number of patients (20 patients with difficult intubation) [3,4]. It must be noted that the four patients which were described by Drs Ates and Alanoglu, were classified as difficult intubation according to Mallampati Class II scoring.

The last comment concerns the cost–benefit of requesting a lateral X-ray prior to operation. At University Hospitals in Iran the cost of a lateral neck X-ray is 20 000 Iranian Rials and with insurance (which almost everyone carries) is 2000 Rials, approximately a quarter of a US Dollar. This cost is considered as very low or negligible and would not bring an additional cost in large-scale hospitals if used as a screening test. I should also note that when an anaesthetist faces an unpredicted difficult intubation it might cost the patient much more. In our setting, a single fibreoptic bronchoscopy costs 100 times more than a single lateral X-ray. However, we agree with the comment that in other institutions, this non-invasive technique will cost more and it may be wise to use it only in patients predicted as a difficult intubation such as patients with higher Mallampati Classes (III–IV).

References

1. Kamalipour H, Bagheri M, Kamali K, Yarmohammadi H. Lateral neck radiography for prediction of difficult orotracheal intubation. Eur J Anaesth 2005; 22: 689–693.
2. Naguib M, Malabarey T, AlSatli RA, Al Damegh S, Samarkandi AH. Predictive models for difficult laryngoscopy and intubation. A clinical, radiologic and three-dimensional computer imaging study. Can J Anaesth 1999; 46: 748–759.
3. Samra SK, Schork MA, Guinto Jr FC. A study of radiologic imaging techniques and airway grading to predict a difficult endotracheal intubation. J Clin Anesth 1995; 7: 373–379.
4. Jimson CT, Eric BR, Ayyaz H. Predicting difficult endotracheal intubation in surgical patients scheduled for general anesthesia: a prospective blind study. Anesth Analg 1995; 81: 254–258.
© 2006 European Society of Anaesthesiology