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The Laryngoscope
VC 2014 The American Laryngological,
Rhinological and Otological Society, Inc.
Does Body Mass Index Predict Tracheal Airway Size?
Brian D’Anza, MD; Jesse Knight, MD; J. Scott Greene, MD, FACS
Objectives/Hypothesis: To determine the relationship between body mass index along with other anthropomorphic
variables as they relate to tracheal airway dimensions.
Study Design: Retrospective case series.
Methods: This was a radiographic study of 123 consecutive hospitalized patients undergoing tracheotomy over a 4-year
period (2007–2011). We measured airway dimensions in axial computed tomography imaging and made comparisons with
height, weight, body mass index, gender, and age. Measurements were taken at the first tracheal ring level including anterior-
posterior length, width, and calculated area. We expected higher body mass index not to be a good predictor of larger airway
dimensions.
Results: The linear regression model showed body mass index was significantly inversely related to tracheal width after
controlling for gender and age (P 5.0389). For every 1 kg/m2 increase in body mass index, the tracheal width decreased by
0.05 mm. There was a trend for airway area to diminish with increasing body mass index.
Conclusions: These results are consistent with the hypothesis that obese patients do not have larger airways. Our study
indicated a trend toward smaller airways as body mass index increased. Specifically, as body mass index increases, tracheal
width appears to decrease. This information should help medical professionals avoid the tendency to use a larger tube to
secure the airway of an obese patient. Hopefully, this will result in further research into the field and may prevent future air-
way injuries in a society where obesity has become epidemic.
Key Words: Tracheal airway size, endotracheal tube size, obesity.
Level of Evidence: 4
Laryngoscope, 125:1093–1097, 2015
INTRODUCTION
General guidelines exist for endotracheal tube
(ETT) size selection in adults.1,2 Variations in the choice
of tube selection are influenced by factors such as
patient age, gender, and body habitus. Generally speak-
ing, a larger diameter tube is used for adult males and
those with larger body habitus when compared to
females or smaller individuals. Tracheostomy tube selec-
tion follows similar decision making algorithms in the
adult population.3 Due to normal anatomical variability,
it is difficult to standardize recommendations for endo-
tracheal and tracheostomy tube sizes for adults.4 On a
case-by-case basis, considerations for choosing a tube
size might include those mentioned previously. Body
dimensions that could be used to predict airway sizes
include body mass index (BMI). A literature review
shows the lack of a study comparing BMI with airway
dimensions.
Larger-than-necessary ETTs are known to cause
laryngeal or tracheal trauma and are to be avoided.
Common problems can include laryngeal webs, vocal
cord ulcerations, vocal cord paralysis or paresis, subglot-
tic stenosis, and tracheal stenosis among others.5,6 How-
ever, our experience has shown the tendency of
emergency medical providers and critical care physicians
to place a larger tube in a larger patient. Based on our
observations at time of tracheotomy, we have found that
it is common to find a smaller than anticipated trachea
in an obese patient. Based on this experience, we
hypothesize that higher BMI is not a good predictor of
larger airway size. The purpose of our study was to eval-
uate the airway dimensions and identify anatomical con-
cerns for the use of relatively oversized ETTs in an
obese population. We measured airway dimensions in
axial computed tomography (CT) imaging of 123 patients
who underwent tracheotomy and made comparisons
with their height, weight, BMI, gender, and age.
MATERIALS AND METHODS
The Geisinger Medical Center Office of Research Compli-
ance and Institutional Review Board approved the retrospective
electronic chart case series titled Predictors of Airway Size. The
study was performed reviewing the information on 123 patients
who underwent tracheotomy surgery by the otolaryngology
department over a 4-year period (2007–2011) and who also had
CT imaging of the trachea within the previous 3 months.
Anthropomorphic measurements were taken from the time of
From the Department of Otolaryngology, Head and Neck Surgery,
Facial Plastic Surgery (B.D., J.S.G), Geisinger Medical Center, Danville,
Pennsylvania; and the ENT Associates of Los Alamos, PLLC (J. K.), Los
Alamos, New Mexico, U.S.A.
Editor’s Note: This Manuscript was accepted for publication
September 3, 2014.
Presented at the 2013 American Academy of Otolaryngology–Head
and Neck Surgery National Meeting, Vancouver, British Columbia, Can-
ada, September 30, 2013.
The authors have no funding, financial relationships, or conflicts
of interest to disclose.
Send correspondence to Brian D’Anza, MD, Department of Otolar-
yngology, Head and Neck Surgery, Facial Plastic Surgery, Geisinger
Medical Center, 100 N. Academy Ave., Danville, PA 17822. E-mail:
DOI: 10.1002/lary.24943
Laryngoscope 125: May 2015 D’Anza et al.: BMI and Tracheal Airway Size
Reprinted by permission of Laryngoscope. 2015; 125(5):1093-1097.
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