Original contribution
Tracheal width and left double-lumen tube size: a formula to estimate left-bronchial width

https://doi.org/10.1016/j.jclinane.2004.07.008Get rights and content

Abstract

Study Objective

To determine which patient parameters best predict left bronchial width (LBW) when selecting the correct size double-lumen tube (DLT). If LBW is known, a DLT that will fit that bronchus can be chosen.

Design

Prospective study.

Setting

University medical center.

Patients

Three hundred twenty-one consecutive patients scheduled for thoracic surgery and for whom there was a chest radiograph and for whom tracheal width (TW) and LBW could be measured.

Measurements

Tracheal width and LBW were directly measured from the chest radiograph. Patient demographic data were recorded and then analyzed to see which factor(s) best predicted LBW. Parameters often used for DLT selection (age, sex, height, and weight) as well as TW were compared by univariate and multivariate statistical analysis to see which factor(s) most accurately predicted LBW.

Main Results

There were weak but significant correlations between age and height and LBW in men, and height and LBW in women. Multivariate statistical analysis showed that, for both men and women, TW was the best predictor of LBW. Sex, height, and weight did not improve predictability over TW alone. The equation that best predicts LBW for both sexes is: LBWmm = (0.50)(TWmm) + 3.7 mm. This model explains 46% of the variance in LBW. As structures measured from a chest radiograph are magnified by 10%, the formula to predict LBW, which normalizes for this magnification factor, is: LBWmm = (0.45)(TWmm(CXR)) + 3.3 mm.

Conclusions

Direct airway measurement is the most accurate way to select an appropriate DLT. However, when direct measurement of LBW cannot be performed, estimating LBW from TW is a better predictor of LBW than either sex, height, or weight.

Introduction

The wrong-sized double-lumen tube (DLT) can damage an airway or compromise the surgical procedure. We directly measured left bronchial width (LBW) from chest radiographs and then tried to identify which patient parameter(s) best predicted LBW. Once LBW is known, then a left-DLT whose bronchial component fits that bronchus can be selected.

Section snippets

Materials and methods

With the permission of the Stanford University Medical Center’s Human Subjects Committee, we enrolled in the study 321 consecutive patients scheduled for thoracic surgery. Of the 321 patients, 192 patients (60%; 112 males, 80 females) had available a posterior-anterior chest radiograph in which both the trachea and left-bronchial air columns were clearly visible. Only those 192 patients were included in the data analysis.

The width of the trachea (TW, mm) at the level of the clavicles was

Results

Table 1 shows the demographic data for the patients.

In the univariate correlation analysis (Table 2), LBW was positively associated with height, age, and TW in males, and with height and TW in females. In the multivariate regression analysis, TW was the only factor that independently predicted LBW (Fig. 1). Sex, weight, height, and age did not contribute to a further reduction in the variance of LBW.

Based on chest radiographical measurement, the equation that best predicts LBW for both sexes

Discussion

Choice of DLT size is important. A small tube is more likely to be advanced further into the bronchus where it can obstruct the upper lobe [1]. The lumens of smaller tubes offer greater resistance to airflow [2], [3] and generate higher levels of auto-PEEP during 1-lung ventilation [4]. A tube that is too large or too small can damage the airway.

The most accurate way to choose a DLT is to directly measure LBW. If LBW and the dimensions of the DLT are known, then the largest tube that can safely

References (14)

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