Bronchial Length Research Articles

Is there a correlation between right bronchus length and diameter with age?

Right main bronchial anatomy knowledge is essential to guide endoscopic stent placement in modern era. The aim is to describe right bronchial anatomy, cross-area and its relation with the right pulmonary artery and patient's age. One hundred thirty four cadaveric specimens were studied after approval by the Research and Ethics Committee at the University of São Paulo Medical School and Medical Forensic Institute of São Paulo. All necropsies were performed in natura after 24 hours of death and patients with previous pulmonary disease were excluded. Landmarks to start measurement were the first tracheal ring, vertex of carina, first right bronchial ring, and right pulmonary artery area over the right main bronchus. After mobilization, the specimens were measured using a caliper and measurement of distances was recorded in centimeters at landmarks points. All the measures (distances, cross sectional area and planes) were performed by three independent observers and recorded as mean, standard error and ranges. Student t test was used to compare means and linear regression was applied to correlate the measurements. From 134 specimens studied, 34 were excluded (10 with previous history of pulmonary diseases, surgery or deformities and 24 of female gender). Linear regression showed proportionality between tracheal length and right bronchus length; with the area at first tracheal ring and carina and also between the cross sectional area at these points. Linear regression analysis between tracheal length and age (R=0.593 P<0.005), right bronchus length and age (R=0.523, P<0.005), area of contact between right bronchus and right pulmonary artery and age (R=0.35, P<0.005). We can conclude that large airways grow progressively with increasing age in male gender. There was a direct correlation between age and tracheal length; as has age and right bronchus length. There was a direct correlation between age and the area of the right bronchus covered by the right pulmonary artery.

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

PurposeIntensive 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 methodsUsing 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.ResultsStatistical 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: 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 , 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: 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 , respectively. The distal external transverse diameter rose from 2.09 ± 0.47 to 4.24 ± 0.20 mm, as y = - 8.723 + 4.021x{text{ ln(Age)}} pm 0.392 for the right main bronchus, and from 1.85 ± 0.04 to 3.67 ± 0.66 mm, like y = - 6.924 + 3.280x{text{ ln(Age)}} pm 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 y = - 10.212 + 0.943x{text{ Age}} pm 1.739 and y = - 19.119 + 1.875x{text{ Age}} pm 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.ConclusionsThe 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.

Airway Morphology From High Resolution Computed Tomography in Healthy Subjects and Patients With Moderate Persistent Asthma

ABSTRACTModels of the human respiratory tract developed in the past were based on measurements made on human tracheobronchial airways of healthy subjects. With the exception of a few morphometric characteristics such as the bronchial wall thickness (WT), very little has been published concerning the effects of disease on the tree structure and geometrical features. In this study, a commercial software package was used to segment the airway tree of seven healthy and six moderately persistent asthmatic patients from high resolution computed tomography images. The process was assessed with regards to the treatment of the images of the asthmatic group. The in vivo results for the bronchial length, diameter, WT, branching, and rotation angles are reported and compared per generation for different lobes. Furthermore, some popular mathematical relationships between these morphometric characteristics were examined in order to verify their validity for both groups. Our results suggest that, even though some relationships agree very well with previously published data, the compartmentalization of airways into lobes and the presence of disease may significantly affect the tree geometry, while the tree structure and airway connectivity is only slightly affected by the disease. Anat Rec, 296:852–866, 2013. © 2013 Wiley Periodicals, Inc.

Airway Morphology From High Resolution Computed Tomography in Healthy Subjects and Patients With Moderate Persistent Asthma

Models of the human respiratory tract developed in the past were based on measurements made on human tracheobronchial airways of healthy subjects. With the exception of a few morphometric characteristics such as the bronchial wall thickness (WT), very little has been published concerning the effects of disease on the tree structure and geometrical features. In this study, a commercial software package was used to segment the airway tree of seven healthy and six moderately persistent asthmatic patients from high resolution computed tomography images. The process was assessed with regards to the treatment of the images of the asthmatic group. The in vivo results for the bronchial length, diameter, WT, branching, and rotation angles are reported and compared per generation for different lobes. Furthermore, some popular mathematical relationships between these morphometric characteristics were examined in order to verify their validity for both groups. Our results suggest that, even though some relationships agree very well with previously published data, the compartmentalization of airways into lobes and the presence of disease may significantly affect the tree geometry, while the tree structure and airway connectivity is only slightly affected by the disease.

CT findings of a displaced left upper division bronchus in adults: Its importance for performing safe left pulmonary surgery

PurposeThe aim of this study was to describe the CT findings of a displaced left upper division bronchus (DLUDB) in adults. Materials and methodsTen patients with DLUDB were identified. The following CT features were assessed: origin of the DLUDB; distance between the origin of the DLUDB and the origin of the left upper lobe (LUL) bronchus; height of the origin of the DLUDB against the left pulmonary artery (LPA); difference of the main bronchial length; ventilated segment; course of the left pulmonary artery against the DLUDB; and presence of an accessory fissure or other anomalies. ResultsDLUDB arose from the posterolateral or lateral aspect of the left main bronchus immediately proximal to the origin of the LUL bronchus. It tended to course along the posterior wall of the LPA and to ventilate the apicoposterior segment with or without the anterior segment. The LPA passed between the displaced bronchus and the lingular bronchus. The origin of the DLUDB was located lower than the inferior wall of the proximal LPA in 6 patients. The accessory fissure between the associated segment and remaining part of the LUL and right tracheal bronchus coexisted in 7 and 3 patients respectively. ConclusionDLUDB has characteristic findings on CT. Radiologists should be aware of this entity and inform the surgeon as it can prevent serious complications in a patient who may undergo lobectomy of the left lung.

Thoracic Situs As an Indicator of Atrial Appendage Morphology: A Postmortem Study of 306 Specimens With Situs Solitus in 250 and Heterotaxy in 56 Cases

Symmetry of bronchi, lung lobation, and atrial appendages is frequently found in patients with heterotaxy syndromes. To evaluate the reliability of thoracic situs as an indicator of atrial appendage morphology, thoracic situs was assessed in 306 postmortem cases: 250 with atrial situs solitus and 56 with heterotaxy syndromes. Five features that indicate thoracic situs were assessed: (1) lung lobation, (2) lengths of main bronchi, (3) ratio of left to right (L/R) bronchial lengths, (4) relationship of bronchi to ipsilateral pulmonary artery, and (5) number of cartilage rings in each main bronchus. In the group with heterotaxy, the expected symmetrical lung lobation, lengths of bronchi, number of cartilage rings, and relations to pulmonary arteries were found in 77, 77, 77, and 95% of cases, respectively. The ratios of L/R bronchial lengths were ≤ 1.5 in 90% of cases. The relations of the bronchi to the pulmonary arteries were the best predictors of symmetrical atrial appendages or splenic syndromes. Bronchial-atrial discordance occurred in ten cases: in situs solitus in one case and in heterotaxy in nine cases. Detection of heterotaxy syndromes is important because of the associated severe congenital cardiac defects. No single feature of thoracic situs is completely reliable. All available data should be used to make the diagnosis.

High-resolution three-dimensional 19F-magnetic resonance imaging of rat lung in situ: evaluation of airway strain in the perfluorocarbon-filled lung

Perfluorocarbons (PFC) are biologically and chemically inert fluids with high oxygen and CO2 carrying capacities. Their use as liquid intrapulmonary gas carriers during liquid ventilation has been investigated. We established a method of high resolution 3D-19F-MRI of the totally PFC-filled lung. The goal of this study was to investigate longitudinal and circumferential airway strain in the setting of increasing airway pressures on 3D-19F-MR images of the PFC-filled lung. Sixteen female Wistar rats were euthanized and the liquid perfluorocarbon FC-84 instilled into their lungs. 3D-19F-MRI was performed at various intrapulmonary pressures. Measurements of bronchial length and cross-sectional area were obtained from transversal 2D images for each pressure range. Changes in bronchial area were used to determine circumferential strain, while longitudinal strain was calculated from changes in bronchial length. Our method of 3D-19F-MRI allowed clear visualization of the great bronchi. Longitudinal strain increased significantly up to 31.1 cmH2O. The greatest strain could be found in the range of low airway pressures. Circumferential strain increased strongly with the initial pressure rise, but showed no significant changes above 10.4 cmH2O. Longitudinal strain was generally higher in distal airways, while circumferential strain showed no difference. Analysis of mechanical characteristics showed that longitudinal and circumferential airway expansion occurred in an anisotropic fashion. Whereas longitudinal strain still increased with higher pressures, circumferential strain quickly reached a ‘strain limit’. Longitudinal strain was higher in distal bronchi, as dense PFCs gravitate to dependent, in this case to dorso-basal parts of the lung, acting as liquid positive end expiratory pressure.

Anatomical dimensions of trachea, main bronchi, subcarinal and bronchial angles in fetuses measured ex vivo

The increasing opportunities to consider fetal intervention in selected cases of life-threatening malformations have necessitated airway management of fetuses with low gestational age. This study is aimed to determine the anatomical dimensions of trachea, main bronchi, subcarinal and bronchial angles and their correlation to age and crown rump length (CRL) in fetuses. Measurements of tracheo-bronchial dimensions including the subcarinal and bronchial angles with the vertical were taken in specimens obtained from 40 fetuses, varying in CRL from 61 to 270 mm. The incidence of different shapes at the upper end of trachea was studied. The subcarinal and angles of main bronchi with the vertical were measured radiographically with 20% barium sulfate, in another group of 21 fetuses varying in CRL from 63 to 129 mm. Forty fetuses (22 males, 18 females) were analyzed for the dimensions based on CRL (61-130 mm; 131-200 mm; 201-270 mm--CRL 1, 2, and 3 respectively). The internal transverse diameter of trachea was found to increase steadily from 1.87 +/- 0.56 to 2.67 +/- 0.7 mm (P < 0.001) and 3.68 +/- 0.39 mm (P < 0.001) with increasing CRL. Similarly the outer transverse and antero-posterior diameter of the trachea increased steadily with age. Tracheal length was found to increase significantly to 17.48 +/- 2.89 mm and 24.17 +/- 2.3 from 12.72 +/- 2.5 mm (P < 0.001). The length of paries membranaceous increased with gestational age. Although the length of bronchi increased significantly and linearly, subcarinal and bronchial angles did not show any significant changes with age. There was no sexual dimorphism in measurements in the fetuses of corresponding CRL. Oval shaped trachea was found in 60% and circular in 40% of fetuses. The measurements of subcarinal and bronchial angles performed by radiology were almost the same as those measured in trachea separated from fetuses. The internal transverse, outer transverse and antero-posterior diameters, length of trachea and bronchi and circumference of trachea, relate in a linear fashion to CRL and age. However, subcarinal and bronchial angles remained constant.

C-arm guided placement of Fogarty embolectomy catheter for one lung ventilation in an infant - A case report -

We experienced one lung anesthesia using Fogarty embolectomy catheter as a bronchial blocker in an infant undergoing thoracotomy for foreign body removal. For the guidance of catheter placement in left mainstem bronchus, C-arm fluoroscopy was used. Size of catheter and its balloon was decided beforehand by measuring the diameter and length of bronchus based on the view obtained from computerized tomography. There was no accidental episode during anesthesia. C-arm fluoroscopy is safe and useful method to decide the position of Fogarty occlusion catheter in an infant.

Assessment of bronchial wall thickness and lumen diameter in human adults using multi‐detector computed tomography: comparison with theoretical models

A thickened bronchial wall is the morphological substratum of most diseases of the airway. Theoretical and clinical models of bronchial morphometry have so far focused on bronchial lumen diameter, and bronchial length and angles, mainly assessed from bronchial casts. However, these models do not provide information on bronchial wall thickness. This paper reports in vivo values of cross-sectional wall area, lumen area, wall thickness and lumen diameter in ten healthy subjects as assessed by multi-detector computed tomography. A validated dedicated software package was used to measure these morphometric parameters up to the 14th bronchial generation, with respect to Weibel's model of bronchial morphometry, and up to the 12th according to Boyden's classification. Measured lumen diameters and homothety ratios were compared with theoretical values obtained from previously published studies, and no difference was found when considering dichotomic division of the bronchial tree. Mean wall area, lumen area, wall thickness and lumen diameter were then provided according to bronchial generation order, and mean homothety ratios were computed for wall area, lumen area and wall thickness as well as equations giving the mean value of each parameter for a given bronchial generation with respect to its value in generation 0 (trachea). Multi-detector computed tomography measurements of bronchial morphometric parameters may help to improve our knowledge of bronchial anatomy in vivo, our understanding of the pathophysiology of bronchial diseases and the evaluation of pharmacological effects on the bronchial wall.

Quantification of bronchial dimensions at MDCT using dedicated software

This study aimed to assess the feasibility of quantification of bronchial dimensions at MDCT using dedicated software (BronCare). We evaluated the reliability of the software to segment the airways and defined criteria ensuring accurate measurements. BronCare was applied on two successive examinations in 10 mild asthmatic patients. Acquisitions were performed at pneumotachographically controlled lung volume (65% TLC), with reconstructions focused on the right lung base. Five validation criteria were imposed: (1) bronchus type: segmental and subsegmental; (2) lumen area (LA)>4 mm2; (3) bronchus length (Lg) > 7 mm; (4) confidence index - giving the percentage of the bronchus not abutted by a vessel - (CI) >55% for validation of wall area (WA) and (5) a minimum of 10 contiguous cross-sectional images fulfilling the criteria. A complete segmentation procedure on both acquisitions made possible an evaluation of LA and WA in 174/223 (78%) and 171/174 (98%) of bronchi, respectively. The validation criteria were met for 56/69 (81%) and for 16/69 (23%) of segmental bronchi and for 73/102 (72%) and 58/102 (57%) of subsegmental bronchi, for LA and WA, respectively. In conclusion, BronCare is reliable to segment the airways in clinical practice. The proposed criteria seem appropriate to select bronchi candidates for measurement.

The Lengths of the Left and Right Mainstem Bronchi Measured by Computed Tomography with Minimum Intensity Projection in Korean Adults

Background: Accurate knowledge of the mainstem bronchial lengths is essential in order to prevent malpositioning of the double lumen endobronchial tubes (DLT). It is believed that the lengths of the left and right mainstem bronchi measured by CT are more accurate than those measured using a fiberoptic bronchoscope. This study evaluated the length of the mainstem bronchus using a CT scan in Korean adults. Methods: One hundred twenty patients who underwent a chest CT scan without any anatomical changes due to a mass or inflammation were examined. Airway imaging with a minimum intensity projection of the oblique coronal section using multidetector CT was obtained and the lengths of the left and right mainstem bronchi were measured. Results: The lengths of the left mainstem bronchus of the males and females were 49.2 ± 4.8 mm and 44.6 ± 3.9 mm respectively, and the right mainstem bronchus of the males and females were 21.0 ± 4.8 mm and 18.0 ± 4.0 mm, respectively. There was no linear correlation between the height of the patients and the length of the left and right mainstem bronchi. Conclusions: These results provide reference data to help determine the precise margin of safety using a double lumen endobronchial tube for thoracic surgery. (Korean J Anesthesiol 2006; 51: 426~9)

A double-lumen tube technique for selective lobar isolation

EDITOR: A 72-yr-old female (height 162 cm, weight 55 kg) was admitted to our Intensive Care Unit (ICU) because of acute respiratory failure (PaO2/inspired O2 fraction (FiO2) 10.3 kPa). On admission, her trachea was intubated with a 7.5 mm inner diameter endotracheal tube (Portex, Kent, UK) and lungs mechanically ventilated in a pressure-regulated volume-controlled mode (Siemens 300C®, Berlin, Germany). Tidal volume was set at 380-400 mL, respiratory rate 20 breaths min−1, externally applied positive end-expiratory pressure (PEEP) 0 cmH2O. The achieved PaO2/FiO2 was 12 kPa. The patient was sedated with propofol (4 mg kg−1 h−1). The admission chest radiograph revealed diffuse, bilateral pulmonary infiltrates. She had no prior history of chronic inhalation of dusts causing inflammation and pulmonary fibrosis. Microbiological, serological and imaging investigations for patients with suspected interstitial lung disease [1] failed to establish a definitive, causal diagnosis. Thus, surgical lung biopsy [1-4] under selective lobar collapse [5] was decided. For selective left upper lobar collapse, the following technique was employed. (a) Determination of left mainstem bronchus length. A 3.4 mm fibreoptic bronchoscope was inserted through the original endotracheal tube; the upper incisor-to-carina distance (23.5 cm) was determined by subtracting the endotracheal tube connector-to-upper incisor length (part of endotracheal tube protruding from the patient's mouth) from the fibreoptic bronchoscope insertion length at the level of carina (endotracheal tube connector-to-carina); in a similar way, the upper incisor-to-left upper bronchus orifice distance (26.0 cm) was determined by subtracting the endotracheal tube connector-to-upper incisor length from the fibreoptic bronchoscope insertion length at the level of the left upper bronchus orifice; lastly, the difference of the aforementioned distances yielded the left mainstem bronchus length (2.5 cm). (b) LUL isolation. Additional propofol (1 mg kg−1), fentanyl (3 μg kg−1) and cisatracurium (0.2 mg kg−1) were given. Then the original endotracheal tube was replaced by a 37-FG, left-sided, double-lumen tube (BronchoCath®; Mallinckrodt Medical Inc., St. Louis, MO, USA); the double-lumen tube was inserted to the 28.0 cm mark at upper incisor level, and the inflation of both tracheal and bronchial cuffs resulted in the desired selective LUL isolation (Fig. 1).Figure 1: Selective isolation of the left upper lobe with the left-sided double-lumen tube inserted to the 28 cm mark.(c) Confirmation of LUL isolation. A fibreoptic bronchoscope inspection via the tracheal lumen of the double-lumen tube revealed the carina and both mainstem bronchial orifices; on inspection through the bronchial lumen only the segmental left lower bronchial orifices were visualized; on chest auscultation, with both double-lumen tube cuffs inflated, breath sounds were diminished solely over the left upper lobe. In the right lateral decubitus position, the desired double-lumen tube positioning was reconfirmed as above. Following left upper lobe collapse [5], an uneventful videothoracoscopic biopsy of the left upper lung was performed within 40 min. Intraprocedural ventilator settings were: FiO2, 1.0; tidal volume, 350-360 mL; respiratory rate, 23 breaths min−1; inspiratory time-to-total respiratory cycle time ratio 0.5; externally applied PEEP 0 cmH2O. Peak, plateau and mean airway pressures were 45-46, 28-30 and 8-9 cmH2O, respectively; intrinsic PEEP was 2 cmH2O. PaO2 was maintained ≥8 kPa throughout the procedure. In patients in respiratory failure with a short (≈2.5 cm) left mainstem bronchus [6], we recommend our selective left upper lung isolation technique for open lung biopsy. The left lower lobe can still be ventilated through the left endobronchial lumen of the double-lumen tube and the right lung is ventilated through the tracheal lumen. This is likely to minimize the risk of intraoperative hypoxaemia. S. D. Mentzelopoulos K. Rellos M. J. Tzoufi A. S. Michalopoulos Department of Intensive Care Medicine; Henry Dunant General Hospital; Athens, Greece E. P. Papageorgiou Department of Anaesthesiology; Henry Dunant General Hospital; Athens, Greece

Study of Lengths from the Upper Incisor to Left and Right Mainstem Bronchial Carina in Korean Adults Using a Fibroptic Bronchoscope

Background: Accurate knowledge of mainstem bronchial lengths are required to prevent malpositioning of double lumen endobronchial tubes (DLT). Therefore we evaluated the length of the mainstem bronchus in Korean adults who had no abnormalities in both mainstem bronchus. Methods: Two-hundred Thirty-seven patients were composed of One-hundred one males and One- hundred Thirty-six females who underwent elective surgery. After an endotracheal tube was placed, we measured the length from the upper incisor to the tracheal carina, the right mainstem bronchial carina, and the left mainstem bronchial carina using a fiberoptic bronchoscope. Results: The lengths from the upper incisor to the carina of a male and female were 26.8±1.8 cm and 23.6±1.9 cm respectively, and the correlations between their length and height are significant for male and female (r=0.32, P<0.01 and r=0.56, p<0.0001). The lengths from the upper incisor to the right mainstem bronchial carina of male and female were 29.0±2.0 cm and 25.3±2.2 cm respectively, and the correlations between their length and height are significant for male and female (r=0.39, P<0.0001 and r=0.59, P<0.0001). The lengths from the upper incisor to the left mainstem bronchial carina of male and female were 32.0±2.1 cm and 28.5±2.1 cm respectively, and the correlations between their length and height are significant for male and female (r=0.45, P<0.0001 and r=0.60, P<0.0001). Conclusions: We found that as the height of patients increased, the length from the upper incisor to the carina, the right mainstem bronchial carina, and the left mainstem bronchial carina increased. Nevertheless, it should be understood that the length of DLT insertion at any given height is still normally distributed, and correct DLT positioning should always be confirmed fiberoptically after the initial placement. (Korean J Anesthesiol 2001; 40: 572~576)

Novel adaptation of a method to assess responsiveness of bronchial segments in vitro.

In vivo agonist delivery to the lungs is characterized by absorption through the mucosal layer followed by access to the smooth muscle. When agonists are applied to perfused bronchial segments, a difference in potency to agonists applied to the serosal (outside) or mucosal (inside) surface can be demonstrated. In order to elucidate this effect in canine bronchial segments, we adapted a method to assess responsiveness of agonists applied to the inside or outside surface of canine bronchial segments. A 2 cm "fluid-tight" length of bronchus was cannulated and mounted in a perfusion chamber. Auxotonic contraction of the bronchus displaced fluid inside the segment up a column and the change in height of fluid within the column (afterload) was measured as a change in hydrostatic pressure (volumetric). We assessed the optimal conditions for measuring bronchial responsiveness to acetylcholine. Neither stretching segments lengthways from 100 to 140% of resting length, nor altering the transmural pressure from 3 to 21 cmH2O had a significant effect on the potency of acetylcholine applied to the outside surface. Both acetylcholine (n=7) and methacholine (n=4) were approximately 10-fold more potent when applied to the outside surface than the inside surface of bronchial segments (p<0.0001). Furthermore, mechanical removal of the epithelium (n=6) led to a 67-fold increase in potency of acetylcholine applied to the inside surface compared with segments with epithelium. The advantages that this system has over previously reported methods include: 1) agonists can be injected at a low flow rate so as to minimize epithelial stress; 2) changes in luminal volume are measured under conditions of no flow; 3) after-load can be varied such that contraction is either practically isotonic or auxotonic; and 4) a "barrier effect" of the epithelium of canine bronchial segments can be demonstrated. This new adapted method will provide us with the means to assess the relationship between in vitro and in vivo responsiveness in human bronchi.

Endoscopic anatomy and map of the equine bronchial tree.

To develop a bronchoscopic map of the equine respiratory tree, the major airways of the lungs of 6 healthy Thoroughbred horses were systematically explored with a flexible fibreoptic endoscope through a tracheostomy while the horses were sedated in stocks. With the carina as the reference point, measurements were made of distances to the branches of the major airways using markers on the shaft of the endoscope. All branches were explored until the narrowing of their diameters prevented further advancement of the endoscope. Positions of origins of branches from the parent bronchus were recorded in relation to a 12 h clock. Branching patterns of the right and left lungs were similar. Seventeen branches of the principal and caudal lobar bronchi of the left lung, and 18 branches of the principal and caudal lobar bronchi of the right lung were identified. Mean explorable distances from the carina to the ends of the right and left caudal lobar bronchi were 34.0 +/- 3.5 (sd) and 34.5 +/- 3.0 cm, respectively. Generally, smaller horses had shorter explorable bronchial lengths. Branching patterns of the parent bronchi were fairly consistent among horses, particularly the branches closest to the carina. After endoscopy and euthanasia, the lungs were removed, and dried with pressurised air flowing through them for 7-10 days. Attempts to explore the airways of the dried lungs endoscopically were relatively unsuccessful, because airways were much smaller in the dried lungs, and many of the branches were distorted when compared with their antemortem appearances. However, having a dried lung specimen as a reference during the bronchoscopic procedure was useful for maintaining orientation in the lungs. Radiographs were used to estimate the location of the origin and destination of each airway branch in relation to the nearest intercostal space. This makes the airway map useful when lesions identified radiographically are to be lavaged.

Determining deposition sites of inhaled lung particles and their effect on clearance

An essential component of lung defense is clearance of particulates and infectious vectors from the mucus membrane of the tracheobronchial tree and the alveolar regions of the lung. To partition clearance between these areas we determined the bronchial branching pattern, the anatomical sites of particle deposition, and subsequent clearance in the same animal. Using a 2.85-microns particle tagged with 57Co for inhalation and deposition in the sheep lung, we followed clearance via a series of computer-stored gamma-scintillation lung images. The same sheep was reinhaled, and the particle distributions for both inhalations were compared. After the animals were killed, the bronchial branching pattern and length of the bronchial tree were documented. The number of particles depositing in all bronchi down to 1 mm diam was determined by scintillation counting, and the number in respiratory bronchioles and alveoli was microscopically counted. We conclude that particles deposited in bronchi greater than or equal to 1 mm diam clear in 2-4 h postdeposition. Bronchi distal to 1-mm-diam bronchi and alveoli clear evenly over 72 h, and the number of particles equal to the tracheobronchial deposition cleared after 45 h.

Margin of safety in positioning modern double-lumen endotracheal tubes.

The authors have defined the margin of safety in positioning a double-lumen tube as the length of tracheobronchial tree over which it may be moved or positioned without obstructing a conducting airway. The purpose of this study was to measure the margin of safety in positioning three modern double-lumen tubes (Mallinkrodt [Broncho-Cath], Rusch [Endobronchial tubes], and Sheridan [Broncho-Trach]). The margin of safety in positioning a: 1) left-sided double-lumen tube (all manufacturers) is the length of the left mainstem bronchus minus the length from the proximal margin of the left cuff to left lumen tip; 2) Mallinkrodt right-sided double-lumen tube is the length of the right mainstem bronchus minus the length of the right cuff; and 3) Rusch right-sided double-lumen tube is the length of the right upper lobe ventilation slot minus the diameter of the right upper lobe. The length of the right and left mainstem bronchi were measured by in vivo fiberoptic bronchoscopy (n = 69), in fresh cadavers (n = 42), and in lung casts (n = 55), and the diameter of the right upper lobe bronchus was measured in lung casts (n = 55). The average +/- SD male left and right mainstem bronchial lengths were 49 +/- 8 and 19 +/- 6 mm, respectively, the average +/- SD female left and right mainstem bronchial lengths were 44 +/- 7 and 15 +/- 5 mm, respectively, the average right upper lobe bronchial diameter was 11 mm, the proximal left cuff to left lumen tip distance was 30 mm, the length of the Mallinkrodt right cuff was 10 mm, and the length of the Rusch right upper lobe ventilation slot was 15 mm. The average margin of safety in positioning left-sided double-lumen tubes ranged 16-19 mm for the different manufacturers. The average margin of safety in positioning Mallinkrodt right-sided double-lumen tubes was 8 mm, and the margin of safety in positioning Rusch right-sided double-lumen tubes ranged 1-4 mm, depending on French size. The authors concluded that left-sided double-lumen tubes are much preferable to right-sided double-lumen tubes because they have a much greater positioning margin of safety, and that proper confirmation of proper position of either a left- or right-sided double-lumen tube should be aided by fiberoptic bronchoscopy, because the absolute distances that constitute the margin of safety are extremely small.

Photoradiation therapy of endobronchial lung cancers employing the photodynamic action of hematoporphyrin derivative.

Thirty-five patients with tumors within the tracheobronchial tree were treated with photoradiation therapy (PRT) employing the photodynamic action of hematoporphyrin derivative (HPD). An effective protocol has been developed consisting of 3.0 mg/kg HPD given intravenously 72 hours prior to the bronchoscopic illumination of the endobronchial tumor sites with red light (630 nm) from an argon pumped dye laser. Light applicators were developed that provided surface (area) and insertion (volume) illumination of tumor masses. Average light dosages of 100 J/cm2 and 200 J/cm were used for surface and insertion illumination, respectively. Delivery rates were 200 mW/cm2 and 400 mW/cm. There was no immediate visible effect such as coagulation or charring noted. All malignant endobronchial tumors responded. Tumors included primary and metastatic lesions of various histologic types. Response was complete for tumor within the bronchus after one treatment in 80% of instances. The remaining cases required two treatments to obtain a complete response due to the extensive length of bronchus involved or because multiple sites were present. A complete response, that is, the full opening up of the lumen to the bronchial wall, was accomplished in all but one instance. Atelectatic lungs or lobes were re-expanded and reaerated. Dyspnea and cough became significantly less. The follow-up achieved to date indicates improvement in symptoms, activity level, and the return to work in a significant number of cases.

Bronchial length and diameter behavior during bronchial collapse in excised dog lungs

We compared changes in bronchial diameters (Dbr) and lengths (Lbr) in six excised dog lobes at 4 volume levels during deflation from 30 cm HP 2O under two conditions. First, intrabronchial and alveolar pressures were kept equal to zero during lund deflation; then, bronchial collapse was induced by negative intrabronchial pressure at several constant lung volumes. During the two procedures the major intrapulmonary bronchai were isolated from the rest of the lung by 10–15 beads blocking all tributary bronchi as previously described. Lbr was estimated with a linear displacement transducer connected by a thin rod to the most distal bead. Mean Dbr was calculated from Lbr and bronchial volume at each lung recoil pressure (P L) and at each intrabronchial pressure (Pbr). When P L decreased from full inflation in Condition 1, Dbr and Lbr decreased almost proportionately; however, in Condition 2 when P L (and thus lung volume) was kept constant and Pbr was reduced from 0 to −80 cm H 2O, Lbr was reduced by only 5% (mean) whereas Dbr was reduced by 70% (mean) from initial near-homogeneous values. This suggested that, due to the interdependence in intact lungs, Lbr in intact lungs is almost constrained by changes in lung volume. By contrast, Dbr can undergo large reductions and the stiffness of intact bronchi is related mainly to P L. Thus, the intact bronchus has some of the characteristics of a thick-walled cylinder (where the wall includes surrounding parenchyma) in which longitudinal strain in small by comparison with circumferential strain.