CT assessment of tracheal carinal angle and its determinants

PneumaOCT: Pneumatic optical coherence tomography endoscopy for targeted distortion-free imaging in tortuous and narrow internal lumens

The complex anatomy of internal luminal organs, like bronchioles, poses challenges for endoscopic optical coherence tomography (OCT). These challenges include limited steerability for targeted imaging and nonuniform rotation distortion (NURD) with proximal scanning. Using rotary micromotors for distal scanning could address NURD but raises concerns about electrical safety and costs. We present pneumaOCT, the first pneumatic OCT endoscope, comprising a steerable catheter with a soft pneumatic actuator and an imaging probe with a miniature pneumatic turbine. With a diameter of 2.8 mm, pneumaOCT allows for a bending angle of up to 237°, facilitating navigation through narrow turns. The pneumatic turbine enables adjustable imaging speeds from 51 to 446 revolutions per second. We demonstrate the pneumaOCT in vivo imaging of mouse esophagus and colon, as well as targeted and distortion-free imaging of peripheral bronchioles in a bronchial phantom and a porcine lung. This advancement substantially improves endoscopic OCT for navigational imaging in curved and narrow lumens.

Individualized rotation of left double lumen endobronchial tube to improve placement success rate: a randomized controlled trial

BACKGROUND

In conventional practice, the left double lumen tube (DLT) is rotated 90° counterclockwise when the endobronchial cuff passes glottis. Success rate upon the first attempt is < 80%, likely owing to varying morphology of the bronchial bifurcation.

METHODS

We conducted a randomized controlled trial to compare 90° counterclockwise rotation versus individualized degree of rotation in adult patients undergoing elective thoracic surgery using left DLT. The degree of rotation in the individualized group was based on the angle of the left main bronchi as measured on computed tomography (CT). The primary outcome was the first attempt left DLT placement success rate.

RESULTS

A total of 556 patients were enrolled: 276 in the control group and 280 in the individualized group. The average angle of the left main bronchi was 100.6±9.5° (range 72° to 119°). The first attempt left DLT placement success rate was 82.6% (228/276) in the control group versus 91.4% (256/280) in the individualized group (P=0.02, χ2 test). The rate of carina mucosal injury, as measured at 30 min after the start of surgery under fibreoptic bronchoscopy, was significantly lower in individualized group than control group (14.0% versus 19.6%, P=0.041). The individualized group also had lower rate of postoperative sore throat (29.4% versus 44.0%, P<0.001) and hoarseness (16.8% versus 24.7%, P＜0.05).

CONCLUSIONS

Individualized rotation of left DLT based on the angle of the left main bronchi on preoperative CT increased first attempt success rate in adult patients undergoing elective thoracic surgery.

TRIAL REGISTRATION

The trial is registered at Chinese Clinical Trial Registry (ChiCTR2100053349; principal investigator Xiang Quan, date of registration November 19, 2021).

Detection of tracheal branching with computerized tomography: The relationship between the angles and age-gender

BACKGROUND

The data obtained on the anatomical knowledge of the tracheobronchial system can be used for diagnosis, treatment and interventional interventions in areas such as anesthesia, thoracic surgery, pulmonary physiology.

AIM

To determine the tracheobronchial branching angles in pediatric and adult populations by using the multislice computed tomography (CT) and minimum intensity projection (MinIP) technique, which is a non-invasive method.

METHODS

Our study was carried out retrospectively. Patients who underwent contrast and non-contrast CT examination, whose anatomically and pathophysiologically good tracheobronchial system and lung parenchyma images were obtained, were included in the study. Measurements were made in the coronal plane of the lung parenchyma. In the coronal plane, right main bronchus-left main bronchus angle, right upper lobe bronchus-intermedius bronchus angle, right middle lobe bronchus-right lower lobe bronchus angle, left upper lobe bronchus-left lower lobe bronchus angle were measured.

RESULTS

The study population consisted of 1511 patients, 753 pediatric (mean age: 13.4 ± 4.3; range: 1-18 years) and 758 adults (mean age: 54.3 ± 17.3; range: 19-94 years). In our study, tracheal bifurcation angle was found to be 73.3° ± 13.7° (59.6°-87°) in the whole population. In the pediatric group, the right-left main coronal level was found to be higher in boys compared to girls (74.6° ± 12.9° vs 71.2° ± 13.9°, P = 0.001). In the adult group, the right-left main coronal level was found to be lower in males compared to females (71.9° ± 12.9° vs 75.8° ± 14.7°, P < 0.001).

CONCLUSIONS

Our study, with the number of 1511 patients, is the first study in the literature with the largest number of patient populations including pediatric and adult demographic data, measuring the angle values of the tracheobronchial system using multislice CT and MinIP technique. Study data will not only be a guide during invasive procedures, but it can also guide studies to be done with imaging methods.

Treatment of aerodigestive fistulas with a novel covered metallic Y-shaped segmented airway stent customized with the assistance of 3D printing

Background

The management of aerodigestive fistula remains challenging. An airway stent that matches well with the individual geometry of the airway is needed for the treatment of the aerodigestive fistula. This study aimed to evaluate the feasibility of a novel covered metallic segmented Y-shaped airway stent customized with the assistance of 3D printing in aerodigestive fistulas involving the carina and distal bronchi and to compare the flexibility of the novel stent with the conventional wholly knitted stent.

Methods

In the flexibility study, we measured the longitudinal bending force and spring-back force of the segmented stent and wholly knitted stent. Patient-specific stents that were individually customized with the assistance of 3D printing technology were implanted in 26 patients with aerodigestive fistulas. The technical success, clinical success, Karnofsky performance status (KPS), and stent-related complications were recorded.

Results

The bending force and spring-back force of the segmented stent were significantly lower than those of the wholly knitted stent. Stent deployment was technically successful in all patients. Clinical success was obtained in 21 patients. The KPS of patients after the stenting procedure improved significantly compared with that before stenting (P<0.001). During follow-up, granulation tissue proliferation, sputum retention, stent migration, and intolerance of the stent were found in 2, 5, 1, and 1 patient, respectively.

Conclusions

The segmented metallic Y-shaped airway stent had greater flexibility than the wholly knitted stent in an ex vivo setting. Implantation of the segmented stent individually customized with the aid of 3D printing is feasible in treating aerodigestive fistulas involving the carina and bronchi distal to the carina.

The lengths of trachea and main bronchus in Chinese Shanghai population

The knowledge of airway length is the theoretical basis in the diagnosis and management of airway disease. The objective of this study is to measure the length of trachea and left and right main bronchus in Chinese Shanghai population. A total of 153 consecutive adult patients with minor pulmonary disease in Xinhua hospital were enrolled for bronchoscopy examination. Measurements were conducted on head and neck neutral position and height, weight and age for each patient were recorded either. Student t test and multiple linear regression was used to compare means between males and females and to analyze correlation among height, weight, sexual dimorphism and the lengths of the trachea and bronchus. The lengths of the trachea and left main bronchus are significantly different between male and female patients (P < 0.01), but not for the lengths of right main bronchus between man and woman. Multiple linear regression analysis showed that height but not sexual dimorphism and weight correlated with the lengths of the trachea and right main bronchus. The lengths of the trachea and left main bronchus are significantly longer in males than in females. Moreover, height but not sexual dimorphism and weight influenced the length of airway.

3D-measurement of tracheobronchial angles on inspiratory and expiratory chest CT in COPD: respiratory changes and correlation with airflow limitation

Purpose

To assess tracheobronchial angles and their changes on combined inspiratory and expiratory thoracic computed tomography (CT) scans and to determine correlations between tracheobronchial angles and several indices of chronic obstructive pulmonary disease (COPD).

Materials and methods

A total of 80 smokers underwent combined inspiratory and expiratory CT scans. Of these, 65 subjects also performed spirometry and 55 patients were diagnosed with COPD. On CT scans, 3-dimensinal tracheobronchial angles (trachea–right main bronchus [RMB], trachea–left main bronchus [LMB], and RMB–LMB) were automatically measured by software. Lung volumes at inspiration and expiration were also automatically calculated. Changes in tracheobronchial angles between inspiration and expiration were assessed by the Mann–Whitney test. Correlations of the angles with lung volume, airflow limitation, and CT-based emphysema index were evaluated by Spearman rank correlation.

Results

The trachea–LMB angle was significantly smaller and the RMB–LMB angle was significantly larger at expiration than inspiration (P<0.0001). The trachea–LMB and RMB–LMB angles were significantly correlated with lung volume, particularly at expiration. The RMB–LMB angle was significantly correlated with airflow limitation and CT emphysema index (P<0.001–0.05) at inspiration and expiration, suggesting that narrowed RMB–LMB angle indicates more severe airflow limitation and larger extent of emphysema.

Conclusion

Tracheobronchial angles change during respiration and are correlated with severity of COPD and emphysema.

Airway dimensions from fetal life to adolescence-A literature overview

BACKGROUND

Data on airway dimensions in pediatric patients are important for proper selection of pediatric airway equipment such as endotracheal tubes, double-lumen tubes, bronchial blockers, or stents. The aim of the present work was to provide a synopsis of the available data on pediatric airway dimensions.

METHODS

A systematic literature search was carried out in the PubMed database, Scopus, Embase, Web of Science, Prisma, and Google Scholar and secondarily completed by a reference search. Based on inclusion and exclusion criteria, a final selection of 109 studies with data on pediatric airway dimensions published from 1923 to 2018 were further analyzed.

RESULTS

Six different airway measurement methods were identified. They included anatomical examinations, chest X-ray, computed tomography, magnetic resonance tomography, bronchoscopy, and ultrasound. Anatomical studies were more abundant compared to other methods. Data provided were very heterogeneously presented and powered. In addition, due to different study conditions, they are hardly comparable. Among all, anatomical and computer tomography studies are thought to provide the most reliable data. Ultrasound is an upcoming technique to estimate airway parameters of fetus and premature infants. There was, in general, a lack of comprehensive studies providing a complete range of airway dimensions in larger groups of patients from birth to adolescence.

CONCLUSIONS

This work revealed a large heterogeneity of studies providing data on pediatric airway dimensions, making it impossible to compare, or assemble them to normograms for clinical use. Comprehensive studies in large population of children are needed to provide full range nomograms on pediatric airway dimensions.

Lower airway dimensions in pediatric patients-A computed tomography study

BACKGROUND

The aim of this study was to obtain lower airway dimensions in children by means of computed tomography (CT).

METHODS

Chest CT scans from 195 pediatric patients (118 boys/77 girls) aged 0.04-15.99 years were analyzed. Tracheal and bronchial lengths, anterior-posterior and lateral diameters, as well as cross-sectional area were assessed at the following levels: mid trachea, right proximal and distal bronchus, proximal bronchus intermedius, and left proximal and distal bronchus. Mediastinal angles of tracheal bifurcation were measured. Data were analyzed by means of linear and polynomial regression plots.

RESULTS

The strongest correlations were found between tracheal and bronchial diameters and age as well as between tracheal and bronchial lengths and body length. All measured airway parameters correlated poorly to body weight. Bronchial angles revealed no association with patient's age, body length, or weight.

CONCLUSION

This comprehensive anatomical database of lower airway dimensions demonstrates that tracheal and bronchial diameters correlate better to age, and that tracheal and bronchial length correlate better to body length. All measured airway parameters correlated poorly to body weight.

The Tracheal Accordion and the Position of the Endotracheal Tube

The purpose of this review is to, first, determine the static factors that affect the length of the human trachea across different populations and, second, to investigate whether or not there are dynamic factors that cause the length of the human trachea to vary within the same individual. We also investigated whether these changes in tracheal length within the same individual are significant enough to increase the risk of endobronchial intubation or accidental extubation. A PubMed/MEDLINE and a Web of Science database English-language literature search was conducted in May 2016 with relevant keywords and MeSH terms when available. We found that gender, extremes of age, patient height, postsurgical changes and co-existing disease are static patient factors that affect the length of the human trachea. Dynamic clinical changes that occur under anaesthesia, including Trendelenburg position, head and neck flexion and extension, paralysis of the diaphragm and pneumoperitoneum, cause the trachea to act as an accordion, decreasing and increasing its length. The length of the human trachea in both awake and anaesthetised and paralysed patients is a critical consideration in preventing both endobronchial intubation and tracheal extubation. It is clear from the literature that tracheal length varies widely across populations and, additionally, with the dynamic clinical changes that occur under anaesthesia, the trachea acts as an accordion decreasing and increasing its length within the same individual. Knowledge of the magnitude of the change in tracheal dimensions in response to these factors is an important clinical consideration.

Tracheobronchial Angle Measurements in Children: An Anthropometric Retrospective Study With Multislice Computed Tomography

OBJECTIVES

The purpose of this study is to investigate if any change exists in the values of tracheal bifurcation angles (subcarinal angle [SCA] and interbronchial angle [IBA]), right and left bronchial angles (RBA and LBA) in different pediatric age groups.

METHODS

Chest computed tomography (CT) images of children aged 18 years and younger were reviewed retrospectively by two radiologists who were blinded to each other's measurements. One hundred and eighteen children were involved. RBA, LBA, SCA, and IBA were measured on coronal reformatted images. Subjects were classified into three groups according to their age. Measurement of IBA was done by measuring the angle between the lines drawn along the central axis of right and left main bronchi over their length. RBA and LBA were measured at the intersection points of the lines drawn along the inferior borders of the right and left main bronchi and the line passing through the longitudinal axis of trachea. Sums of RBA and LBA gave SCA. Interobserver agreement was also analyzed.

RESULTS

SCA, IBA, and RBA values were statistically significant between children of ages less than 10 years and over 10 years P<0.01). Interobserver agreement was excellent with an intraclass correlation coefficient score of 0.87 (95% confidence interval) for RBA, SCA, and IBA measurements.

CONCLUSION

We concluded that tracheal bifurcation angles are wider in children of age 10 years and younger. As age increases values of SCA, IBA, and RBA decrease.

Anatomy and physiology of respiratory system relevant to anaesthesia

Clinical application of anatomical and physiological knowledge of respiratory system improves patient's safety during anaesthesia. It also optimises patient's ventilatory condition and airway patency. Such knowledge has influence on airway management, lung isolation during anaesthesia, management of cases with respiratory disorders, respiratory endoluminal procedures and optimising ventilator strategies in the perioperative period. Understanding of ventilation, perfusion and their relation with each other is important for understanding respiratory physiology. Ventilation to perfusion ratio alters with anaesthesia, body position and with one-lung anaesthesia. Hypoxic pulmonary vasoconstriction, an important safety mechanism, is inhibited by majority of the anaesthetic drugs. Ventilation perfusion mismatch leads to reduced arterial oxygen concentration mainly because of early closure of airway, thus leading to decreased ventilation and atelectasis during anaesthesia. Various anaesthetic drugs alter neuronal control of the breathing and bronchomotor tone.

Tracheo-bronchial angles in the human fetus -- an anatomical, digital, and statistical study

Background

Both the advancement of visual techniques and intensive progress in perinatal medicine result in performing airway management in the fetus and neonate affected by life-threatening malformations. This study aimed to examine the 3 tracheo-bronchial angles, including the right and left bronchial angles, and the interbronchial angle, in the fetus at various gestational ages.

Material/Methods

Using methods of anatomical dissection, digital image analysis with an adequate program (NIS-Elements BR 3.0, Nikon), and statistics, values of the two bronchial angles and their sum as the interbronchial angle were semi-automatically measured in 73 human fetuses at the age of 14–25 weeks, derived from spontaneous abortions and stillbirths.

Results

No male-female differences between the parameters studied were found. The 3 fetal tracheo-bronchial angles were found to be independent of age. The right bronchial angle ranged from 11.4° to 41.8°, and averaged 26.9±7.0° for the whole analyzed sample. The values of left bronchial angle varied from 24.8° to 64.8°, with the overall mean of 46.2±8.0°. As a consequence, the interbronchial angle totalled 36.2–96.6°, and averaged 73.1±12.7°.

Conclusions

The tracheo-bronchial angles change independently of sex and fetal age. The left bronchial angle is wider than the right one. Values of the 3 tracheo-bronchial angles are unpredictable since their regression curves of best fit with relation to fetal age cannot be modelled. Both of the 2 bronchial angles and the interbronchial angle are of great relevance in the location of inhaled foreign bodies, and in the diagnosis cardiac diseases and mediastinal abnormalities.

Clinical experience with a new endobrochial blocker: the EZ-blocker

PURPOSE

In some thoracic surgical procedures, the insertion of a double-lumen tube (DLT) is not feasible, or the altered use of a DLT and a single-lumen tube (SLT) is justified during the surgery. In the present article we report our experience with a new bronchial blocker, the EZ-blocker, in clinical use.

METHODS

Data were obtained from ten patients undergoing thoracic surgery necessitating one-lung ventilation. For lung isolation, a combination of an SLT and an EZ-blocker was used. The time of insertion and positioning of the EZ-blocker, the lung deflation time with the EZ-blocker cuff inflated and deflated, and the cuff's minimal occlusion volume were recorded. Based on the CT scan, the diameter of the main bronchi and the angle of the bifurcation were measured offline.

RESULTS

The insertion duration of the EZ-blocker was 76 ± 15 s. Two malpositionings were caused by the too-deep positioning of the SLT used for introducing the EZ-blocker, which could be corrected within 65 ± 7 s. The use of the EZ-blocker allowed a short deflation time of the lung without (9.4 ± 0.7 s) and with (4.1 ± 0.7 s) administration of suctioning. The proper block was only dependent on the diameter of the main bronchi and was independent of the bifurcation angle.

CONCLUSIONS

Use of the EZ-blocker is easy and safe. The short insertion time and short lung deflation time through the lumen of the SLT allows its use in emergency situations or in cases of a difficult airway.

The reliability of chest radiographs in predicting left atrial enlargement

INTRODUCTION

Estimates of left atrial size in patients with suspected cardiac disease play an important role in predicting prognosis and events, as well as treatment decisions. Two methods are commonly used to estimate left atrial size: chest radiography and cardiac ultrasound. This study aims to determine the test characteristics by comparing the use of radiographs to cardiac ultrasound (the gold-standard test).

METHODS

Data from patients older than 18 years admitted to Steve Biko Academic Hospital during 2000-2003 who had both chest radiographs and cardiac ultrasound were included in this cross-sectional, retrospective analysis. Chest radiographs were classified into three quality classes, and the sub-carinal angle (SCA) and sub-angle distance (SAD) were measured twice in all available radiographs by two observers. Intra- and inter-observer variability (three methods) as well as the predictive value of the carinal angle and sub-angle distance measurements were determined using logistic regression (with left atrial enlargement - determined by ultrasound as comparator).

RESULTS

Data for 159 patients were available (154 cardiac ultrasounds and 178 chest radiographs). Intra-observer variability for chest radiograph measurements was low with almost perfect concordance (p = 0.000). Inter-observer variability was higher for supine radiographs. Using logistic regression, a linear model was identified which was statistically significant only for erect radiographs. While goodness-of-fit analysis showed that the model fits the data, performance characteristics were poor, with high sensitivity and low specificity, and an area under the ROC curve of 0.62-0.63, depending on type of radiograph and measurement (SCA or SAD). Linearity in the logit of the dependent variable was assessed, and found to be present at the extremes of SCA measurements for the supine radiograph data and in the first three quartiles for erect radiograph data. A nonlinear model determined by fractional polynomial analysis did not perform significantly better than the original linear model. Cut-off values for the SCA of 72° and 84° (erect and supine radiographs, respectively) were found to give the best compromise between sensitivity and specificity. The corresponding cut-off values for SAD were 24.1 and 26.9 mm.

CONCLUSION

Assessment of either SCA or SAD to determine left atrial size was equivalent and repeatable, both with the same observer and between two observers (less so for supine radiographs). While this measure was precise, it was found not to be very accurate. Therefore, chest radiographs are not reliable in predicting left atrial enlargement.

In vivo and in vitro morphometry of the human trachea

Most morphometric studies of the human trachea have relied on plain radiographs with their attendant limitations. Reports using computed tomography (CT) have focused on the growing trachea or one particular dimension. The aim of this study was to document the morphometry of the adult trachea in vivo using high-resolution chest CT scans, supplemented by data from cadavers. Sixty anonymised high-resolution chest CT scans (aged 22-88 years, 40 males) were analyzed. Scans were performed using a standardized breath-holding technique in patients with no distorting intrathoracic pathology. Standardized tracheal measurements included: length, maximum antero-posterior and transverse diameters, volume, subcarinal angle, and carinal position in relation to the tracheal midline. Measurements were also made in 10 cadaver tracheas (aged 68-101 years, 7 males). CT data showed that mean tracheal length (males 105.1 +/- 9.8 mm, females 98.3 +/- 8.7 mm), maximum antero-posterior and transverse diameters, and tracheal volume (males 35.6 +/- 6.8 cm3, females 24.7 +/- 6.1 cm3) were all significantly greater in men (P < or = 0.01). The subcarinal angle was very variable (mean 78 +/- 20 degrees , range 36-121 degrees ) and showed no correlation with age or gender. The carina was sited to the left of the tracheal midline in 49 (81%) patients. Cadaver tracheas had 14-19 tracheal rings and the posterior membranous trachea was wider in men (17.7 +/- 4.4 mm vs. 11.8 +/- 3.0 mm, P = 0.07). In conclusion, there is marked sexual dimorphism in the morphometry of the human trachea. The variation in adult tracheal dimensions in vivo is greater than in standard descriptions. These data may be valuable when interpreting chest CT scans and when calculating respiratory dead space.

Correlative anatomy for thoracic inlet; glottis and subglottis; trachea, carina, and main bronchi; lobes, fissures, and segments; hilum and pulmonary vascular system; bronchial arteries and lymphatics

Because it is relatively inexpensive and universally available, standard radiographs of the thorax should still be viewed as the primary screening technique to look at the anatomy of intrathoracic structures and to investigate airway or pulmonary disorders. Modern trained thoracic surgeons must be able to correlate surgical anatomy with what is seen on more advanced imaging techniques, however, such as CT or MRI. More importantly, they must be able to recognize the indications, capabilities, limitations, and pitfalls of these imaging methods.