Asian Cardiovasc Thorac Ann 1998;6:199-202
© 1998 Asia Publishing EXchange Pte Ltd
Selection and Placement of Double-Lumen Tubes in Asian Patients
Sean Mackey, MD, PhD,
Jay B Brodsky, MD,
Teresa M Alcantara, MD1,
James Monje, MD1,
Florian R Nuevo, MD2
Department of Anesthesiology Stanford University School of Medicine Stanford, CA, USA
1 Section of Thoracic Anesthesia Lung Center of the Philippines Manila, Philippines
2 Division of Anesthesiology Santo Tomas University Hospital Manila, Philippines
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For reprint information contact: Jay B Brodsky, MD Department of Anesthesiology, H-3580 Stanford University Medical Center Stanford, CA 94305, USA Tel: 1 650 723 6411 Fax: 1 650 725 8544 Email: Jbrodsky{at}leland.stanford.edu
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ABSTRACT
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In the first part of the study performed at Stanford University, 30 Asian born and 163 non-Asian born patients matched by height and weight had left-sided double-lumen tubes selected on the basis of the width of each patient's trachea. In the second part of the study performed at the Philippines Lung Center and Santo Tomas University Hospital, left-sided double-lumen tubes were selected on the basis of the anesthesiologists' clinical experience for 22 patients and by tracheal width guidelines for 35 patients. When tubes were selected by tracheal width, there was no difference between those used for Asian and non-Asian patients of similar size. We concluded that measurement of tracheal width can be used to select the appropriate size of left-sided double-lumen tubes for all patients.
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INTRODUCTION
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Selection of the appropriate double-lumen tube (DLT) is important because the wrong size of tube can traumatize the airway and compromise lung separation and oxygenation during one-lung ventilation. We prefer to use the largest DLT that will fit the airway. The choice of DLT is often arbitrary and based on the anesthesiologist's personal experience. It is our impression that a smaller tube will often be chosen for an Asian patient even when a larger DLT would be used for a similarly sized non-Asian patient. We previously described a method of selecting left-sided DLTs based on tracheal diameter measured from the patient's preoperative chest radiograph.1 The goal of this study was to see if that method could be used to predict the appropriate size of DLT for Asian patients and to determine whether there are any differences in DLT size for patients of Asian origin.
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METHODS
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With approval of the Human Subjects Committee at Stanford University Medical Center, patients undergoing thoracic operations requiring tracheal intubation with a DLT were studied. Height and weight were measured preoperatively and the patients were divided into 2 groups. Group 1 (n = 30) comprised 18 male and 12 female patients born in Asia (China, Philippines, Southeast Asia). Group 2 (n = 163) comprised 64 males and 99 females who were selected from a total of 363 non-Asian born patients by matching for height and weight with the group 1 patients. The width of each patient's trachea was measured at the level of the clavicle on a recent postero-anterior chest radiograph. A non-beveled left BronchoCath DLT (Mallinckrodt Medical Inc., St. Louis, MO, USA) was then selected on the basis of that measurement (Table 1
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Following induction of general anesthesia, the DLT was advanced into the left bronchus and the correct position was confirmed using a sequence of clinical maneuvers.2 The depth of placement and any difficulties passing the tube down the airway were recorded. Additional data were provided from the Lung Center of the Philippines and Santo Tomas University Hospital for a patient population that was exclusively Asian. Height, weight, and tracheal width measured from a chest radiograph were recorded for each patient. Two groups were studied. The first group (n = 22) consisted of 19 males and 3 females in whom a left BronchoCath DLT had previously been selected using the anesthesiologists' clinical experience. These patients were retrospectively reviewed, their tracheal width was measured and the size of DLT that could have been used based on tracheal width was calculated. In the second group (n = 35), 20 males and 15 females had left BronchoCath DLTs prospectively selected on individual tracheal measurement.
Statistical analysis was performed using Excel 97 (Microsoft Corp., Redmond, WA, USA) and SPSS V6.0 software (SPSS, Inc., Chicago, IL, USA). Linear regression analysis (method of least squares) was used to evaluate the relationship between depth of placement and patient height. Relationships between gender, tracheal width, height, and weight were assessed using analysis of variance. A p value of less than 0.05 was considered statistically significant.
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RESULTS
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All DLTs in this study functioned properly as evidenced by lack of hypoxemia and successful deflation of the nonoperated lung during one-lung ventilation. Demographics for patients at Stanford University are presented in Table 2. There was no statistically significant difference in height or weight between group 1 and group 2 patients. The average tracheal width for Asian born patients was 19 ± 2 mm for men and 16 ± 2 mm for women. For non-Asian born control patients, average tracheal widths were slightly larger at 21 ± 2 mm for men and 17 ± 3 mm for women but these differences were not significant. In general, the patients from the Philippines study group were smaller than the non-Asian group 2 patients at Stanford University. The male patients in the Philippines study group had tracheal widths of 18 ± 2 mm and the female patients had tracheal widths of 15 ± 1 mm. In all groups, women had significantly narrower tracheal widths than men (p = 0.001). The Philippines measurements were not significantly different from those obtained in Asian born patients at Stanford.
The proportion of large (39 Fr and 41 Fr) versus small (35 Fr and 37 Fr) DLTs used in the 2 groups at Stanford University are shown in Figure 1 (p > 0.005). The regression values relating patient height versus depth of DLT placement for Asian and non-Asian patients respectively were: depth (cm) = 4.9 + 0.36 x height (inches), R2 = 0.44, p < 0.0001; and depth (cm) = 9.4 + 0.29 x height (inches), R2 = 0.44, p < 0.0001. The regression lines were not statistically different from each other as can be seen in Figure 2.
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Figure 1. Selection of a left BronchoCath double-lumen tube based on the tracheal width of the individual patient. There were no differences between Asian born and height and weight-matched control patients in the use of large (41 Fr and 39 Fr) rather than small (35 Fr and 37 Fr) BronchoCath double-lumen tubes.
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Figure 2. The depth of insertion (cm) for left BronchoCath double-lumen tubes in Asian born and non-Asian control patients at Stanford University Medical Center. In both men and women the average depth of insertion was directly proportional to height. The average depth of insertion was 28 cm for patients 165 cm tall. Because these data represent average values for any given height, they are useful only as a guide and should not be used for deciding DLT placement.
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Of the 22 patients in the Philippines study group who were retrospectively studied, 12 of 18 patients (66%) who could have had a large (41 Fr or 39 Fr) tube as predicted by their tracheal width were intubated with a small (35 Fr or 37 Fr) tube. No patient had a 41-Fr BronchoCath DLT because this size of tube was not available although 11 of 19 men had tracheas large enough (
18 mm) to accept a tube that size.
Of the 35 patients in the Philippines study group who were prospectively studied, 11 patients could have had a 41-Fr DLT on the basis of their tracheal widths. Since 41-Fr BronchoCath tubes were not available, 8 of these 11 patients were successfully intubated with the next largest (39 Fr) tube. In the remaining 3 patients, because of difficulties with visualization of the airway during laryngoscopy (prominent incisors, small chin, or very small mouth opening) the anesthesiologist chose to use a smaller DLT than predicted by tracheal width measurements. With the exception of these 3 patients who had a small DLT due to gross anatomic problems, all patients were successfully intubated with the appropriate (largest) size of DLT predicted by their tracheal width.
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DISCUSSION
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The optimal size of DLT is one in which only a small amount of air is required for the bronchial cuff to seal the airway.3 Smaller tubes require more air in their cuff thereby increasing the risks of cuff herniation into the trachea or damage to the airway. More importantly, very small tubes can be advanced further into the bronchus where their bronchial cuff may obstruct the upper-lobe orifice resulting in hypoxemia during one-lung ventilation.4 Although this is a common problem when right-sided DLTs are used because the length of the right bronchus is shorter than the left, left upper lobe obstruction can occur with the smaller left-sided DLTs.4 Smaller DLTs have increased air flow resistance during one-lung ventilation and it is more difficult to advance a fiberoptic bronchoscope or suction catheter through their smaller lumens. The amount of intrinsic positive end-expiratory pressure generated during one-lung ventilation is greater when a small DLT is used.5 Therefore, large DLTs are preferred to reduce problems with tube placement and lung separation during one-lung ventilation. We have previously shown that for both men and women, height and weight were not reliable criteria for choosing the appropriate size of DLT.1 Since the outer diameters of the tracheal and bronchial lumens of the left BronchoCath DLT are known for each size of tube, the width of each patient's bronchus should determine the optimal size of DLT for that individual. Unfortunately, the left bronchus is often obscured on the chest radiograph thereby preventing direct measurement.3 However, there is a significant correlation between the ratio of the diameter of the left bronchus and the trachea; left bronchus diameter = 0.68 x tracheal width.6 Therefore, since the trachea is always visible on the chest radiograph, measurement of tracheal width can be used to predict left bronchial width thus allowing selection of the largest DLT that could fit that airway.
We found no statistical difference in the size of DLT that could be used between similar sized Asian and non-Asian patients. While in general, Asian patients tend to be physically smaller than non-Asian patients, identical-sized left BroncoCath DLTs were selected and successfully placed in similarly sized patients when the choice was based on tracheal width alone. The fact that in our retrospectively studied group from the Philippines, 66% of patients who could have been intubated with a large DLT received a small tube, confirms our belief that smaller tubes are often chosen for Asian patients when the choice of tube size is subjective. When tracheal width guidelines were used prospectively, all patients had their airways intubated with an appropriate-sized (largest) tube predicted for them. Furthermore, in the Stanford study groups, the depth of placement of the DLT was found to correlate with patient height and did not differ between Asian and non-Asian patients of similar height.
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CONCLUSION
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We concluded that there is no difference in the size of left BronchoCath DLT that can be used in similar-sized Asian and non-Asian patients. Several other plastic DLTs are commercially available but since each manufacturer's DLT differs in their tracheal and bronchial lumen dimensions, these conclusions apply to left BronchoCath DLTs only.3 The use of right DLTs was not studied. Using tracheal width guidelines, we found that large left BronchoCath DLTs can be placed safely in many Asian patients and this knowledge should reduce the problems associated with the use of smaller DLTs.
Presented in part at The Annual Meeting of the American Society of Anesthesiologists, San Diego, California, USA, October 1997.
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REFERENCES
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Brodsky JB, Shulman MS, Mark JBD. Malposition of left-sided double-lumen endobronchial tubes. Anesthesiology
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Jesseph JE, Merendino KA. The dimensional interrelationships of the major components of the human tracheobronchial tree. Surg Gynecol Obstet
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ABSTRACT
INTRODUCTION
