Sir,
We read with interest the article by Ohri and Malhotra outlining the feasibility of tongue volume assessment with three different ultrasonographic (USG) computation methods wherein they demonstrate the equivalence of the methods in predicting difficult airway (DA).[1] While the authors are commended for the novelty of the idea and noteworthy inclusions such as objective definitions of easy, restricted and difficult laryngoscopy, a few important points need to be elucidated.
The comparative presentation of the estimated tongue volume measurements in patients with easy (54%), restricted (42%) and difficult laryngoscopy (4%) would have accounted for an improved evaluation of the parameter in DA prediction
As an extension of the aforementioned, derivation of tongue volume cut-off value in prediction of DA from the index study could serve an interesting comparison to the 100 cm3 cut-off described by Wojtczak et al. and Parameswari et al.[2,3]
The lack of substantial combined sensitivity and specificity of the tongue volume DA predictive value in the present study involving only 50 patients (with 4% DA) mandates discussion with respect to the clinical value of the parameter. Moreover, tongue volume values should be cautiously interpreted in patients with a decreased thyromental distance wherein tongue volume can be well within normal range despite a thicker and shorter tongue precluding an easy intubation.[4] Some researchers also emphasise the importance of assessing the tongue volume in relation to the mandibular volume.[3]
To conclude, the literature in the area of USG-DA prediction is evolving rapidly adding further depth and breadth to the research area while the clinical significance of the newer parameters continues to be actively investigated across diverse ethnicities and clinical contexts.
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Conflicts of interest
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REFERENCES
- 1.Ohri R, Malhotra K. Different 2D ultrasound calculation methods to evaluate tongue volume for prediction of difficult laryngoscopy. Indian J Anaesth. 2020;64(15 Suppl):S193–7. doi: 10.4103/ija.IJA_843_19. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Wojtczak JA. Submandibular sonography: Assessment of hyomental distances and ratio, tongue size, and floor of the mouth musculature using portable sonography. J Ultrasound Med. 2012;31:523–8. doi: 10.7863/jum.2012.31.4.523. [DOI] [PubMed] [Google Scholar]
- 3.Parameswari A, Govind M, Vakamudi M. Correlation between preoperative ultrasonographic airway assessment and laryngoscopic view in adult patients: A prospective study. J Anaesthesiol Clin Pharmacol. 2017;33:353–8. doi: 10.4103/joacp.JOACP_166_17. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Yao W, Wang B. Can tongue thickness measured by ultrasonography predict difficult tracheal intubation? Br J Anaesth. 2017;118:601–9. doi: 10.1093/bja/aex051. [DOI] [PubMed] [Google Scholar]