Predicting the Size of a Double-Lumen Endobronchial Tube Using Computed Tomographic Scan Measurements of the Left Main Bronchus Diameter

Effect of a 3D-printed reconstruction automated matching system for selecting the size of a left double-lumen tube: a study protocol for a prospective randomised controlled trial

INTRODUCTION

Lung isolation is primarily accomplished using a double-lumen tube (DLT) or bronchial blocker. A precise and accurate size of the DLT is a prerequisite for ensuring its accurate placement. Three-dimensional (3D) reconstruction technology can be used to accurately reproduce tracheobronchial structures to improve the accuracy of DLT size selection. Therefore, we have developed automatic comparison software for 3D reconstruction based on CT data (3DRACS). In this study, we aimed to evaluate the efficiency of using 3DRACS to select the DLT size for endobronchial intubation in comparison with using the 'blind' DLT intubation method to determine the DLT size, which is based on height and sex.

METHODS AND ANALYSIS

This is a prospective, single-centre, double-blind randomised controlled trial. In total, 200 patients scheduled for lung resection using a left DLT will be randomly allocated to the 3D group or the control group at a 1:1 ratio. A 3DRACS will be used for the 3D group to determine the size of the DLT, while in the case of the control group, the size of the DLT will be determined according to patient height and sex. The primary outcome is the success rate of placement of the left DLT without fibreoptic bronchoscopy (FOB). The secondary outcomes include the following: successful intubation time, degree of pulmonary atrophy, grade of airway injury, oxygenation during one-lung ventilation, postoperative sore throat and hoarseness, and number of times FOB is used.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from our local ethics committee (approval number: SCCHEC-02-2022-155). Written informed consent will be obtained from all participants before randomisation, providing them with clear instructions about the purpose of the study. The results will be disseminated through peer-reviewed publications and conferences.

TRIAL REGISTRATION NUMBER

NCT06258954.

A bench study on the prevention of lung-to-lung aspiration with double-lumen endobronchial tubes and bronchial blockers

Effective lung isolation prevents lung-to-lung aspiration during thoracotomy for the management of hemoptysis. Double-lumen endobronchial tubes (DLT) and bronchial blockers are commonly used for lung separation during thoracic surgery. In this study, the fluid-sealing characteristics of the endobronchial cuffs of three different commercially available DLTs (Broncho-Cath with a polyvinylchloride cuff, Broncho-Cath with a polyurethane cuff, and Human Broncho with a silicone cuff) and two different bronchial blockers (Arndt and Coopdech bronchial blockers) were evaluated using a benchtop model. The lateral decubitus position for the surgical management of bleeding from the right lung was simulated. The artificial tracheobronchial tree was placed horizontally, with the left bronchus in the dependent position and the right bronchus in the non-dependent position. In the DLT experiments, the tracheobronchial tree was intubated with left-sided DLTs, and the endobronchial cuff was inflated to maintain the intracuff pressure at 25 cmH2O. In the experiments with bronchial blockers, each bronchial blocker was inserted into the right bronchus, and the endobronchial cuff was inflated to seal the main bronchus. A fluid leakage test around the endobronchial cuff was performed using three different types of DLT (size 35, 37, and 41 Fr, each) and two different types of bronchial blockers (9 Fr). The 5 mL of colored water was poured into the right bronchus to simulate the blood flow from the operative side, and the times to the first and 100% leakage around the endobronchial cuff were recorded. Each bronchial blocker showed significantly less leakage over time than the other DLTs (P < 0.05). Fluid was not fully leaked around the cuffs for 24 h with either bronchial blocker. The times to first and 100% leakage were not significantly different among different types of DLTs. The times to first and 100% leakage did not also differ among the three different sizes of each type DLT. There was no significant difference in the time to first leakage around the endobronchial cuffs between Arndt and Coopdech bronchial blockers. Bronchial blockers provided a more effective seal against lung-to-lung aspiration than DLTs in the lateral decubitus position for thoracotomy in the benchtop model.

Effect-site concentrations of remifentanil for smooth emergence from combined epidural-general anesthesia or general anesthesia in patients using video double-lumen tube: A randomized trial

Objective

The present study aimed to determine the effect-site concentration of remifentanil of 90% (EC90) for smooth emergence in patients with a video DLT (VDLT) under sevoflurane-maintained general anesthesia and to investigate whether the EC90 was affected by epidural anesthesia.

Methods

One hundred and twenty patients who underwent video-assisted thoracic surgery (VATS) were enrolled. Patients received either general anesthesia combined with epidural anesthesia (PEA group, n = 60) or general anesthesia (GA group, n = 60). The primary outcome was the EC90 for smooth emergence in both groups. The secondary outcomes were intraoperative emergence, smooth emergence, recovery, and hemodynamic profiles in both groups.

Result

The EC90 values for smooth emergence in patients using VDLT were 3.5 ng/ml (95% confidence interval [CI], 3.3-4.4 ng/ml) in the PEA group and 2.7 ng/ml (95% CI, 2.5-3.2 ng/ml) in the GA group. The total amount of remifentanil infusion during emergency was significantly higher in the PEA group (164.6 ± 47.9 μg) than in the GA group (127.1 ± 30.4 μg) (P < 0.001). The number of patients who experienced hypotension during emergency in the PEA group was higher than that in the GA group (46.7% versus 13.3%, P < 0.001).

Conclusion

The EC90 of remifentanil for smooth emergence in patients with VDLT under general anesthesia combined with epidural anesthesia (3.5 ng/ml) was higher than that under general anesthesia (2.7 ng/ml).

Trial registration

Chinese Clinical Trial Registry, ChiCTR2100054230.

Effect of the VivaSight double-lumen tube on the incidence of hypoxaemia during one-lung ventilation in patients undergoing thoracoscopic surgery: a study protocol for a prospective randomised controlled trial

INTRODUCTION

A double-lumen tube (DLT) is a traditional one-lung ventilation tool that needs to be positioned under the guidance of a fibreoptic bronchoscope or auscultation. The placement is complex, and poor positioning often causes hypoxaemia. In recent years, VivaSight double-lumen tubes (v-DLTs) have been widely used in thoracic surgery. Because the tubes can be continuously observed during intubation and the operation, malposition can be corrected at any time. However, the effect of v-DLT on perioperative hypoxaemia has been rarely reported. The aim of this study was to observe the incidence of hypoxaemia during one-lung ventilation with v-DLT and to compare the perioperative complications between v-DLT and conventional double-lumen tube (c-DLT).

METHODS AND ANALYSIS

One hundred patients planning to undergo thoracoscopic surgery will be randomised into the c-DLT group and the v-DLT group. During one-lung ventilation, both groups of patients will receive low tidal volume for volume control ventilation. When the blood oxygen saturation falls below 95%, the DLT will be repositioned and the oxygen concentration will be increased to improve the respiratory parameters (5 cm H₂O Positive end-expiratory pressure (PEEP) on the ventilation side and 5 cm H₂O CPAP (continuous airway positive pressure) on the operation side), and double lung ventilation measures will be taken in sequence to prevent a further decline in blood oxygen saturation. The primary outcomes are the incidence and duration of hypoxaemia and the number of intraoperative hypoxaemia treatments, and the secondary outcomes will be postoperative complications and total hospitalisation expenses.

ETHICS AND DISSEMINATION

The study protocol was approved by the Clinical Research Ethics Committee of The First Affiliated Hospital, Sun Yat-sen University (2020-418) and registered at the Chinese Clinical Trial Registry (http://www.chictr.org.cn). The results of the study will be analysed and reported.

TRIAL REGISTRATION NUMBER

ChiCTR2100046484.

Choosing the correct-sized adult double-lumen tube: Quest for the holy grail

Appropriate size selection of double-lumen tubes (DLTs) for one-lung ventilation (OLV) in adults is still a humongous task. Several important factors are to be considered like patient height, gender, tracheal diameter, left main bronchial diameter, and cricoid cartilage transverse diameter. In addition to radiological assessment of the airway diameters, the manufacturing details of the particular DLT being used also play a significant role in size selection. Optimal positioning of the appropriately sized DLT is indispensable to avoid complications like airway trauma, cuff rupture, hypoxemia, and tube displacement. It is imperative to know whether the one-size-fits-all dictum holds for DLT size selection as claimed by certain studies. Further randomized studies are required for crystallizing standard protocols ascertaining the correct DLT size. This systematic review article highlights the various parameters employed for DLT size selection and explores the newer DLTs used for adult OLV.

A Randomised Control Study Comparing C-MAC D-Blade Video Laryngoscope (Hyper Angulated Blade) and Macintosh Laryngoscope for Insertion of a Double-Lumen Tube in Patients Undergoing Elective Thoracotomy

Background

The use of a double-lumen endotracheal tube is one of the common anesthetic techniques for operations in the thoracic cavity. However, when compared to a single-lumen tube, placement of a double-lumen tube is technically more difficult as a result of which it takes more time to insert and is associated with more complications such as mucosal injury, hoarseness, and sore throat, even in patients with no anticipated airway difficulty. The CMAC D-blade that is usually used in patients with anticipated airway difficulty, could assist in smooth and quick placement of double-lumen tube (DLT) even in patients with no anticipated airway difficulty.

Aim of the Study

This study aimed to evaluate the effectiveness of the C-MAC D-blade in reducing the time taken to visualize the glottis and intubate patients with normal airway with a double-lumen tube.

Setting and Design

This was a prospective open-label randomized control trial in a tertiary hospital.

Materials and Methods

Seventy-three consenting adult patients with physical status classes I and II, as determined by the American Society of Anesthesiologists, scheduled to undergo elective thoracotomy, were randomly allocated to receive either C-MAC D-blade (Group D) or Macintosh blade (Group M). The primary objective was to compare the time taken for visualization of the glottis and intubation.

Statistical Analysis Used

Chi-square/Fisher's exact test and t-test were used for statistical analysis.

Results

Seventy-three patients were randomized (Group D = 36; Group M = 37). Time to visualize the glottic structures (4.56 ± 2.396 s vs. 7.27 ± 4.891 s, P = 0.01) was significantly better in Group D; however, the mean intubation time was comparable (55.92 ± 18.749 s vs. 51.08 ± 15.269 s, P = 0.61).

Conclusion

C-MAC D-blade videolaryngoscope offers a better glottic view and lesser time to visualize glottis when compared with the Macintosh laryngoscope. However, the time taken to insert the DLT after visualization was longer. We infer that there is no advantage in the routine use of C-MAC D-blade for DLT insertion in patients with no anticipated airway difficulty.

Compatibility of left-sided double-lumen endobronchial tubes with tracheal and bronchial dimensions: a retrospective comparative study

BACKGROUND

Double-lumen endobronchial tubes (DLT) continue to be the most widely used method for obtaining lung isolation during anesthesia. We compared recommendations for DLT size selection with radiologically assessed lower airway dimensions gathered from a large patient population.

METHODS

For this retrospective comparative study, we assessed computed tomography (CT) scans of 150 adults with no known airway pathologies. Using these scans, we measured the diameter and length of the trachea and the diameter of the mainstem bronchi. These airway dimensions were then compared to the dimensions of left-sided DLTs of three different manufacturers. Size selection was based on one standard textbook's recommendations.

RESULTS

We found the recommended DLT sizes were occasionally too small but more often too large, particularly in the endobronchial airway. With the DLT Vivasight-DL®, mismatching occurred in 28.7% (43/150) of the patients at the distal mainstem bronchus and 8% (12/150) at the tracheal level. This mismatching happened most often in females (left distal mainstem bronchus 34/68, 50%; trachea 9/68, 13.2%). Conversely, the DLT was more often too small for male patients in both the left main bronchus (SHER-I-BRONCH®: 8/82, 9.8%) and the trachea (SHER-I-BRONCH®: 2/82, 2.4%). The endobronchial tube portion was more often too long in females (Vivasight® DLT: 11/68, 16%) than males (9/82, 11%).

CONCLUSIONS

A considerable proportion of the recommended DLT sizes from all three manufacturers was incompatible with individual patient's lower airway dimensions.

Comparison between computerized tomography-guided bronchial width measurement versus conventional method for selection of adequate double lumen tube size

Background:

Selection of adequate size double lumen tube (DLT) is complicated by marked inter-individual variability in morphology and dimensions of tracheobronchial tree. Computerized tomography (CT)-guided left bronchus width measurement has been used to predict adequate size DLT in European and Singapore population; however, no such data exist for Indian population who are racially different. We compared the effect of DLT size selection based on CT-guided bronchial width measurement to the conventional method of DLT selection on the adequacy of both lungs isolation and on the safety margin of right-sided DLT.

Methods:

Fifty-five adults scheduled to undergo thoracotomy were enrolled in this prospective observational study. An appropriate size left- or right-sided DLT with outer diameter 0.5–1 mm smaller than the CT-measured bronchial width was selected for the isolation of lungs. Adequacy of separation was checked using fiberoptic bronchoscope. The safety margin of selected right-sided DLT size was calculated from CT-measured right upper lobe bronchus width and diameter of right upper lobe ventilation slot of the DLT.

Results:

Adequate separation of lungs was achieved in 92.7% of studied population, 90.9% in males, and 95.4% in females. Among these, 54.9% patients required different sized DLT as compared to conventional method. Overall safety of margin of right-sided DLTs was comparable between two methods of DLT selection (median [IQR] 4.8 (3.5–6.8) vs. 6.59 (3.5–7.8), P = 0.317). DLT size with adequate isolation of lung correlated with height, tracheal width (TW) on chest X-ray, and age of the patients. A formula to calculate DLT size based on these variable was derived.

Conclusion:

CT-measured bronchial width predicts the appropriate DLT size better than conventional method. In the absence of CT scan facility, patient height, age, and chest X-ray TW may be used to predict DLT size with reasonable accuracy.

[Risk factors for intraoperative hypoxemia during monopulmonary ventilation: an observational study]

BACKGROUND

Left double-lumen endotracheal tubes have been widely used in thoracic, esophageal, vascular, and mediastinal procedures to provide lung separation. Lacking clear objective guidelines, anesthesiologists usually select appropriately sized double-lumen endotracheal tubes based on their experience with 35 and 37Fr double-lumen endotracheal tubes, which are the most commonly used. We hypothesized the patients with a left main bronchus of shorter length (<40mm) had a greater chance of experiencing desaturation during one lung ventilation, due to obstruction in the orifice of the left upper lobe with the bronchial tube.

METHODS

We included 360 patients with a left double-lumen intubated between September 2014 and August 2015. The patient's age, sex, height, weight, and underlying disease were recorded along with type of surgical procedure and the desaturation episodes. In addition, the width of the trachea and the width and length of the left bronchus were measured using computed tomography.

RESULT

Patients with a left main bronchus length of less than 40mm who underwent intubation with a left double-lumen endotracheal tubes had significantly higher incidence of desaturation (Odds Ratio (OR: 8.087)) during one-lung ventilation. Other related factors of patients identified to be at risk of developing hypoxia were diabetes mellitus (OR: 5.368), right side collapse surgery (OR: 4.933), and BMI (OR: 1.105).

CONCLUSIONS

We identified that patients with a left main bronchus length of less than 40mm have a great chance of desaturation, especially if other desaturation risk factors are present.

Risk factors for intraoperative hypoxemia during monopulmonary ventilation: an observational study

Background

Left double-lumen endotracheal tubes have been widely used in thoracic, esophageal, vascular, and mediastinal procedures to provide lung separation. Lacking clear objective guidelines, anesthesiologists usually select appropriately sized double-lumen endotracheal tubes based on their experience with 35 and 37 Fr double-lumen endotracheal tubes, which are the most commonly used. We hypothesized the patients with a left main bronchus of shorter length (<40 mm) had a greater chance of experiencing desaturation during one lung ventilation, due to obstruction in the orifice of the left upper lobe with the bronchial tube.

Methods

We included 360 patients with a left double-lumen intubated between September 2014 and August 2015. The patient's age, sex, height, weight, and underlying disease were recorded along with type of surgical procedure and the desaturation episodes. In addition, the width of the trachea and the width and length of the left bronchus were measured using computed tomography.

Result

Patients with a left main bronchus length of less than 40 mm who underwent intubation with a left double-lumen endotracheal tubes had significantly higher incidence of desaturation (Odds Ratio (OR: 8.087)) during one-lung ventilation. Other related factors of patients identified to be at risk of developing hypoxia were diabetes mellitus (OR: 5.368), right side collapse surgery (OR: 4.933), and BMI (OR: 1.105).

Conclusions

We identified that patients with a left main bronchus length of less than 40 mm have a great chance of desaturation, especially if other desaturation risk factors are present.

A New Technique to Determine the Size of Double-lumen Endobronchial Tubes by the Two Perpendicularly Measured Bronchial Diameters

The cross-section of the mainstem bronchi is not completely round. For preoperative selection of a double-lumen endobronchial tube size, it may be necessary to measure the mediolateral and the anteroposterior bronchial diameters, which can be measured respectively on chest radiograph and computed tomography. With Internal Review Board approval and patients’ informed consent, 105 elective thoracic surgical patients who needed left-sided double-lumen tubes were enrolled. Double-lumen tube size was selected depending on the arithmetic mean of the mediolateral and anteroposterior bronchial diameters. Moreover, the outer diameters of the bronchial tube should be smaller than both mediolateral and anteroposterior diameters. The recommended bronchial diameter for each double-lumen tube size was chosen so that the mean of the two bronchial diameters was 0 to 2.0 mm larger than the upper limit of 95% confidence interval of the averaged outer diameter of the bronchial tube of the selected double-lumen tube. In no case was the predicted double-lumen tube size inappropriate. Generally, anteroposterior bronchial diameters appeared to be different from mediolateral diameters (P=0.001). The double-lumen tube size to be selected based on only one bronchial diameter was different from the one selected based on two perpendicularly measured bronchial diameters in 54.3% of patients (57/105). Preoperative selection of the double-lumen tube size based on the anteroposterior, mediolateral and mean bronchial diameters seems to be useful in that this may obviate the need to change an inappropriately sized double-lumen tube and may be helpful in reducing the related complications.

Augmentation of curved tip of left-sided double-lumen tubes to reduce right bronchial misplacement: A randomized controlled trial

Background

During intubation with a blind technique, a left-sided double-lumen tube (DLT) can be misdirected into the right bronchus even though its curved tip of the bronchial lumen turns to the left. This right bronchial misplacement may be associated with the tip angle of DLTs. We thus performed a randomized trial to test the hypothesis that the DLT with an acute tip angle enters the right bronchus less frequently than the tube with an obtuse tip angle.

Methods

We randomized surgical patients (n = 1427) receiving a polyvinyl chloride left-sided DLT. Before intubation, the curved tip was further bent to an angle of 135° and kept with a stylet inside in the curved-tip group, but not in the control group. After the tip was inserted into the glottis under direct or video laryngoscopy, the stylet was removed and the DLT was advanced into the bronchus with its tip turning to the left. We checked which bronchus was intubated, and the time and number of attempts for intubation. After surgery, we assessed airway injury, sore throat, and hoarseness. The primary outcome was the incidence of right bronchial misplacement of the DLT.

Results

DLTs were misdirected into the right bronchus more frequently in the control group than in the curved-tip group: 57/715 (8.0%) vs 17/712 (2.4%), risk ratio (95% CI) 3.3 (2.0–5.7), P < 0.001. The difference was significant in the use of 32 (P = 0.003), 35 (P = 0.007), and 37 (P = 0.012) Fr DLTs. Intubation required longer time (P < 0.001) and more attempts (P = 0.002) in the control group. No differences were found in postoperative airway injury, sore throat and hoarseness.

Conclusions

Before intubation of left-sided DLTs, augmentation of the curved DLT tip reduced the right bronchial misplacement and facilitated intubation without aggravating airway injury.

Difficulty in inserting left double-lumen endobronchial tubes at the cricoid level in small-statured women: A retrospective study

BACKGROUND AND AIMS

Left double-lumen endobronchial tube (DLT) sizes are selected using tracheal diameters and left mainstem bronchial diameters (LMBDs) determined from chest radiographs or computed tomography (CT) scans. In Western women, 35-Fr or 37-Fr DLTs are often selected. However, difficulties can be encountered when inserting 32-Fr or 35-Fr DLTs in Japanese women. We investigated success rates for 32-Fr or 35-Fr DLT insertion in Japanese women and determined the causes of unsuccessful DLT insertion.

METHODS

We searched anaesthesia records of Japanese women aged ≥20 years who underwent thoracic surgery with 32-Fr or 35-Fr DLTs between April 2010 and March 2015 in our hospital. In the successful group (SG), patients were intubated using the initially selected DLTs. By contrast, in the unsuccessful group (UG), the DLT size had to be changed. The Mann-Whitney U-test and Fisher's exact test were used to compare groups.

RESULTS

The SG included 149 (96.1%) of 155 cases of 32-Fr DLT use and 119 (95.2%) of 125 cases of 35-Fr DLT use. Patient height was significantly lower in the UG than in the SG for the 35-Fr DLT (P = 0.0036). In seven of 12 UG patients (three for 32-Fr and four for 35-Fr), the transverse diameters of cricoid cartilages were smaller than the DLTs' tracheal diameters, thereby preventing passage through the cricoid cartilages.

CONCLUSION

Along with LMBDs, transverse diameters of cricoid cartilages based on CT scans or ultrasonogram findings may help in selecting the appropriate left DLT size.

A simple blind placement of the left-sided double-lumen tubes

One-lung ventilation (OLV) has been commonly provided by using a double-lumen tube (DLT). Previous reports have indicated the high incidence of inappropriate DLT positioning in conventional maneuvers.After obtaining approval from the medical ethics committee of First Affiliated Hospital of Anhui Medical University and written consent from patients, 88 adult patients belonging to American society of anesthesiologists (ASA) physical status grade I or II, and undergoing elective thoracic surgery requiring a left-side DLT for OLV were enrolled in this prospective, single-blind, randomized controlled study. Patients were randomly allocated to 1 of 2 groups: simple maneuver group or conventional maneuver group. The simple maneuver is a method that relies on partially inflating the bronchial balloon and recreating the effect of a carinal hook on the DLTs to give an idea of orientation and depth. After the induction of anesthesia the patients were intubated with a left-sided Robertshaw DLT using one of the 2 intubation techniques. After intubation of each DLT, an anesthesiologist used flexible bronchoscopy to evaluate the patient while the patient lay in a supine position. The number of optimal position and the time required to place DLT in correct position were recorded.Time for the intubation of DLT took 100 ± 16.2 seconds (mean ± SD) in simple maneuver group and 95.1 ± 20.8 seconds in conventional maneuver group. The difference was not statistically significant (P = 0.221). Time for fiberoptic bronchoscope (FOB) took 22 ± 4.8 seconds in simple maneuver group and was statistically faster than that in conventional maneuver group (43.6 ± 23.7 seconds, P < 0.001). Nearly 98% of the 44 intubations in simple maneuver group were considered as in optimal position while only 52% of the 44 intubations in conventional maneuver group were in optimal position, and the difference was statistically significant (P < 0.001).This simple maneuver is more rapid and more accurate to position left-sided DLTs, it may be substituted for FOB during positioning of a left-sided DLT in condition that FOB is unavailable or inapplicable.

Misplacement of left-sided double-lumen tubes into the right mainstem bronchus: incidence, risk factors and blind repositioning techniques

Background

Double-lumen endobronchial tubes (DLTs) are commonly advanced into the mainstem bronchus either blindly or by fiberoptic bronchoscopic guidance. However, blind advancement may result in misplacement of left-sided DLTs into the right bronchus. Therefore, incidence, risk factors, and blind repositioning techniques for right bronchial misplacement of left-sided DLTs were investigated.

Methods

This was an observational cohort study performed on the data depository consecutively collected from patients who underwent intubation of left-sided DLTs for 2 years. Patients’ clinical and anatomical characteristics were analyzed to investigate risk factors for DLT misplacements with logistic regression analysis. Moreover, when DLTs were misplaced into the right bronchus, the bronchial tube was withdrawn into the trachea and blindly readvanced without rotation, or with 90° or 180° counterclockwise rotation while the patient’s head was turned right.

Results

DLTs were inadvertently advanced into the right bronchus in 48 of 1135 (4.2 %) patients. DLT misplacements occurred more frequently in females, in patients of short stature or with narrow trachea and bronchi, and when small-sized DLTs were used. All of these factors were significantly inter-correlated each other (P < 0.001). In 40 of the 48 (83.3 %) patients, blind repositioning was successful.

Conclusions

Smaller left-sided DLTs were more frequently misplaced into the right mainstem bronchus than larger DLTs. Moreover, we were usually able to reposition the misplaced DLTs into the left bronchus by using the blind techniques.

Trial registration

ClinicalTrials.gov Identifier: NCT01371773.

Measurement and analysis of the tracheobronchial tree in Chinese population using computed tomography

Objective

To ascertain accurate measurements of, and the relationships between, the normative parameters of the tracheobronchial trees in the Chinese population using multi-slice spiral computed tomography (CT) and multi-planar reconstruction (MPR).

Materials and Methods

Measurements were performed on 2107 patients who underwent thoracic CT scans in the PLA General Hospital. The lengths of the trachea and the main stem bronchi, and the sizes of the subcarinal angle were obtained through CT or MPR imaging. Multi-variance analyses were performed to detect potential correlations between obtained parameters.

Results

The mean length of the trachea was 104.9 ± 13.4 mm (107.8 ± 13.2 mm for men and 101.4 ± 12.8 mm for women). The mean lengths of the right and left main stem bronchi were 13.6 ± 4.3 and 48.3 ± 6.5 mm, respectively. The right bronchus angle and the left bronchus angle were 34.9 and 42.5 degrees, respectively. Significant gender differences were found in all the parameters measured except for the angle of the right upper lobe bronchus. There are no statistically significant correlations among these parameters.

Conclusions

The normal reference values and the likely ranges of distribution of the tracheobronchial trees in the Chinese population have been established. Significant gender differences exist in the dimensions of the trachea, with the exception of the Right upper bronchial angle (RUA).

Prevention of lung-to-lung aspiration during emergency thoracic surgery: an experimental study

BACKGROUND

Lung separation is essential for an emergency thoracic surgery for massive hemoptysis. When using a double lumen tube (DLT), a commonly adopted lung separation device during thoracic surgery, a water-tight seal of endobronchial cuff is crucial to prevent lung-to-lung aspiration of blood. In this study, we investigated the fluid sealing characteristics of the endobronchial cuff of a DLT and examined the effect of gel lubrication on the fluid leakage beyond the endobronchial cuff of DLT.

METHODS

An artificial tracheobronchial tree was intubated with a DLT. In the first phase of the study, the intra-cuff pressure of endobronchial cuff of DLT was set to 25, 50, or 100 cmH2O (n = 7, each), and the non-dependent bronchus was filled with 5 ml of water. Fluid leakage to the dependent bronchus beyond the endobronchial cuff was collected for 6 h. The time until leakage was first detected and the time until 100% leakage occurred were measured. In the second phase, the endobronchial cuff was coated with either saline (group C, n = 10) or lubricant gel (group GEL, n = 10), and the same parameters were measured.

RESULTS

In the first phase of the study, the times to first leakage and 100% leakage at an intra-cuff pressure of 25 cmH2O were 21.0 (7.0 - 59.0) sec and 3.0 (2.0 - 4.0) min, respectively. Higher intra-cuff (50 and 100 cmH2O) resulted in longer time for the first leakage and 100% leakage, but the duration was not long enough for clinical purpose. In the second phase, all the DLTs in group C showed 100% fluid leakage during the 6-hour period. In contrast, in group GEL, fluid leakage beyond the endobronchial cuff was detected only in 50% of the DLTs and none of the DLT showed 100% fluid leakage during the study. Among the DLTs which exhibited fluid leakage, the time to first leakage was 252.0 (171.0-305.0) min and the leakage volume at the end of the study period was 0.3〔0.0-1.8〕ml.

CONCLUSIONS

Endobronchial cuff of DLT cannot prevent fluid leakage beyond the endobronchial cuff, but lubricant gel coating on the endobronchial cuff can effectively reduce the lung-to-lung aspiration.

The comparison of the lengths and diameters of main bronchi measured from two-dimensional and three-dimensional images in the same patients

Background

Recently, multi-planar reconstruction of the three-dimensional (3D) spiral chest CT scan has demonstrated superiority in the evaluation of the tracheobronchial tree. The goal of this study was to measure the lengths of the right and left main bronchi and their anteroposterior (AP) and transverse (TR) diameters using the 3D and two-dimensional (2D) images in the same adult respectively, and to evaluate the degree of correlation between them.

Methods

We measured the lengths of the right and left main bronchi from the carina to the first of their branches and the AP and TR diameters at the mid-portion of the right main bronchus and 2 cm below the carina in the left main bronchus. We determined the size of the left-sided double-lumen tube (DLT) based on the measured AP diameter of the left main bronchus from the 3D and 2D images, respectively.

Results

There was moderate correlation between the lengths of both main bronchi obtained from the 3D images and the 2D images, and between the AP diameter of the left main bronchus obtained from the 3D images and the 2D images. Same sized DLTs were estimated in 69% of the men and 34% of the women.

Conclusions

The lengths of the right and left main bronchi and their AP and TR diameters obtained from 3D images were not strongly correlated with those from 2D images. Therefore, a further study is needed to verify the superiority of 3D images in selecting the appropriate size of left-sided DLT.

Predicting the appropriate uncuffed endotracheal tube size for children: a radiograph-based formula versus two age-based formulas

STUDY OBJECTIVES

To determine whether a radiograph-based formula using the tracheal diameter from a chest radiograph predicted the appropriate endotracheal tube (ETT) size in children, and to compare these results with those produced using age-based formulas.

DESIGN

Retrospective, observational study.

SETTING

Medical record review.

MEASUREMENTS

Data from 537 pediatric patients, aged 3 to 6 years, who underwent orotracheal intubation with an uncuffed ETT, were randomly divided into two datasets: one was used to derive a formula and the other was for validation. A radiograph-based formula was obtained by linear regression modeling between the tracheal diameter at the seventh cervical vertebra (C7) on chest radiography and the appropriate ETT size from the estimation dataset (n=268). The appropriate size was defined as the ETT size when air leak pressure was 10 to 30 cmH2O. The predictive ability of this equation was evaluated using the validation dataset (n=269). The primary outcome was the success rate of the prediction.

MAIN RESULTS

The following radiograph-based formula was obtained: ID = 3 + 0.3 × (tracheal diameter at C7). The success rate of the radiograph-based formula was 57%, which is higher than the 32% (P < 0.001) of the standard age-based formula (ID = 4 + age/4) or 43% (P = 0.002) of Penlington's formula (ID = 4.5 + age/4). An underestimation of the actual tracheal size occurred in 65% of cases using the age-based formulas, but in only 19% with the radiograph-based formula (P < 0.001).

CONCLUSIONS

The radiograph-based formula may be useful for predicting the appropriate ETT size in children aged 3 to 6 years.

Novel patterns for the growing main bronchi in the human fetus: an anatomical, digital and statistical study

Purpose

Intensive progress in prenatal medicine results in performing airway management in the fetus affected by life-threatening congenital malformations. This study aimed to examine age-specific reference intervals and growth dynamics for length, proximal and distal external transverse diameters, and projection surface areas of the two main bronchi at varying gestational ages, including their relative growth in length and projection surface area.

Materials and methods

Using anatomical dissection, digital image analysis and statistics, length, proximal and distal external transverse diameters, and projection surface areas of the right and left main bronchi were examined in 73 human fetuses (39 males, 34 females) aged 14–25 weeks, derived from spontaneous abortions and stillbirths.

Results

Statistical analysis showed no sex differences. Between the 14 and 25th week of gestation, the lengths of the right and left main bronchi increased from 1.43 ± 0.18 to 3.18 ± 0.39 mm, and from 2.97 ± 0.16 to 7.58 ± 1.95 mm, in accordance with the functions: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ y = - 4.850 + 2.452 x \; \text{ln}\left( {\text{Age}} \right) \pm 0.400\;{\text{and}}\;y = - 15.005 + 7.093x \; \text{ln} \left( {\text{Age}} \right) \pm 0.579 $$\end{document}y=−4.850+2.452xln(Age)±0.400andy=−15.005+7.093xln(Age)±0.579, respectively. The proximal external transverse diameters of the right and left main bronchi varied from 2.13 ± 0.41 to 4.24 ± 0.20 mm, and from 1.84 ± 0.06 to 3.67 ± 0.66 mm, following the logarithmic models: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ y = - 8.666 + 4.018x \; \text{ln}{\rm (Age)} \pm 0.367\;{\text{and}}\;y = - 6.938 + 3.305x{\text{ ln(Age) }} \pm 0.323 $$\end{document}y=−8.666+4.018xln(Age)±0.367andy=−6.938+3.305xln(Age)±0.323, respectively. The distal external transverse diameter rose from 2.09 ± 0.47 to 4.24 ± 0.20 mm, as \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ y = - 8.723 + 4.021x{\text{ ln(Age)}} \pm 0.392 $$\end{document}y=−8.723+4.021xln(Age)±0.392 for the right main bronchus, and from 1.85 ± 0.04 to 3.67 ± 0.66 mm, like \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ y = - 6.924 + 3.280x{\text{ ln(Age)}} \pm 0.348 $$\end{document}y=−6.924+3.280xln(Age)±0.348 for the left one. On either side, there were no statistically significant differences between values of the proximal and distal transverse diameters of the main bronchus. The projection surface areas of the right and left main bronchi ranged from 2.95 ± 0.19 to 13.34 ± 2.12 mm², and from 5.57 ± 0.21 to 28.52 ± 5.24 mm², as \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ y = - 10.212 + 0.943x{\text{ Age}} \pm 1.739 $$\end{document}y=−10.212+0.943xAge±1.739 and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ y = - 19.119 + 1.875x{\text{ Age}} \pm 3.054 $$\end{document}y=−19.119+1.875xAge±3.054. The two main bronchi revealed a proportionate increase in both length and projection surface area, since the right-to-left bronchial length ratio and the right-to-left bronchial projection surface area ratio were stable, 0.41 ± 0.07 and 0.47 ± 0.08, respectively, throughout the analyzed period.

Conclusions

The main bronchi show no sex differences. The right and left main bronchi grow logarithmically in length and external transverse diameter, and linearly in projection surface area. The right and left main bronchi evolve proportionately, with the right-to-left bronchial ratios of 0.41 ± 0.07 for length, and 0.47 ± 0.08 for projection surface area.

Can ultrasound be useful for predicting the size of a left double-lumen bronchial tube? Tracheal width as measured by ultrasonography versus computed tomography

STUDY OBJECTIVE

To correlate tracheal width as measured by ultrasound with width measured by computed tomography (CT), and to evaluate the possible role of ultrasound in the selection of the proper size of left-sided double-lumen endotracheal tubes (LDLTs).

DESIGN

Two independent, prospective, observational clinical studies (Study 1 and Study 2).

SETTING

University hospital.

PATIENTS

Study 1 included 25 patients and Study 2 included 20 adult thoracic surgery patients who required a LDLT during anesthesia.

INTERVENTIONS AND MEASUREMENTS

In Study 1, CT measurements of tracheal width were made at the coronary plane 0.5 cm above the sternoclavicular joint; CT measurements of the left main bronchus diameter were made 1 cm below the carina. Ultrasound measurement of tracheal width was performed just above the sternoclavicular joint in the transversal section. In Study 2, patients' tracheas were intubated with a LDLT based on ultrasound measurements. The frequencies of incorrect selections of LDLT and unsatisfactory lung collapse were analyzed.

MAIN RESULTS

There was a strong correlation between tracheal width as measured by ultrasound and tracheal width (r=0.882, P<0.001) and left main bronchus width (r=0.832, P<0.001) as measured by CT. In 5 cases (25%), the incorrect LDLT by ultrasound was selected; and one (5%) was found to have an unsatisfactory lung collapse.

CONCLUSION

Measurement of the outer tracheal width by ultrasound can be a useful method for predicting the diameter of left main bronchus and for selecting a LDLT.

Use of a neck brace minimizes double-lumen tube displacement during patient positioning

PURPOSE

When patients are moved from the supine to the lateral decubitus position, the double-lumen endobronchial tube (DLT) is often displaced. The aim of this study was to determine whether a DLT is displaced when there are no movements of the head and neck.

METHODS

One hundred patients scheduled for elective thoracic surgery were randomly divided into control and brace groups. Only a left-sided DLT was used during the study. All patients in the brace group wore a neck collar before the positional change. Using a fibreoptic bronchoscope, the distance from the tracheal opening to the main carina and from the bronchial opening to the bronchial carina was measured in the supine and lateral decubitus positions.

RESULTS

Displacement of the DLT (mean +/- SD) during a change from the supine to the lateral decubitus position was greater in the control group (6.3 +/- 5.5 mm in the trachea; 2.4 +/- 3.6 mm in the bronchus) than in the brace group (2.2 +/- 3.9 mm in the trachea; 0.6 +/- 3.1 mm in the bronchus); (P < 0.001). The incidence of clinically significant displacement, greater than 5 mm from the initial correct position, was higher in the control group than in the brace group (48% vs 12%, P < 0.001).

CONCLUSION

By restricting head and neck movements with a neck brace, the DLT displacement could be minimized while positioning patients for thoracotomy. The main cause of the DLT displacement during lateral positioning appears to be related to movement of the head and neck.