Correlation Between External Body Parameters and Nares-to-Vocal Cord Distance

TL;DR

This study finds that the distance from the nose to vocal cords correlates with simple body measurements like height and weight, which could help in medical procedures.

Contribution

The study identifies new correlations between nares-to-vocal cord distance and external anthropometric parameters in surgical patients.

Findings

NVD correlates most strongly with OC7, SMD, height, and weight in men.

Women also show significant but weaker correlations between NVD and OC7, weight, and SMD.

Age and most other measurements have little to no correlation with NVD.

Abstract

Introduction

Nares-to-vocal cord distance (NVD) is an important anatomical parameter for safe nasotracheal intubation and optimal positioning of nasopharyngeal devices. This study evaluated the relationship between NVD and easily obtained external body measurements in adult surgical patients.

Materials and methods

We conducted a prospective observational study in adults of both sexes undergoing elective surgery under general anesthesia. Using a fiberoptic bronchoscope, we measured NVD from the external nares to the level of the vocal cords. External measurements included height (Ht), weight (Wt), nares-ear tragus distance, nares-mandible angle distance, nares-thyroid distance, thyromental distance, sternomental distance (SMD), sternal length, arm span, and the distance from the external occipital protuberance to the tip of the C7 spinous process (OC7). We assessed correlations between NVD and these anthropometric parameters.

Results

All external body measurements and NVD were greater in men than in women. In the overall cohort and in men, NVD showed the strongest positive correlation with OC7, followed by SMD, Ht, and Wt. In women, NVD also correlated significantly with OC7, Wt, and SMD, although the strength and consistency of these associations were lower than in men. Age and several other external measurements showed little or no meaningful correlation with NVD.

Conclusions

NVD demonstrates clinically relevant associations with simple bedside anthropometric measures, particularly OC7, SMD, Ht, and Wt. These findings suggest that readily obtained external measurements may help clinicians estimate NVD when planning nasotracheal intubation or positioning nasopharyngeal devices, especially in settings where fiberoptic assessment is unavailable. Further research across broader, more diverse populations is needed to refine these relationships and support the development of practical prediction tools for airway management.

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