Length Of Trachea Research Articles

Morphometric analysis of human trachea in adult in Gujarat region by luminal cast Plastination

Background: The trachea makes a significant portion of the conducting airways. In addition to its vital role in breathing, variations in the anatomy of the trachea between individuals could have significant importance in clinics. Objective: To obtain values of length and diameter of human trachea. Material and Methods: The Length, antero-posterior and transverse diameters of the trachea were measured on 28 cast of trachea prepared by luminal cast Plastination in the anatomy department of B. J. medical college of Ahmedabad, Gujarat, India. Result: The maximum length of trachea was 10.59 cm and minimum was 8.51 cm. The mean length of trachea was 9.37 cm. The maximum anteroposterior diameter of trachea was 2.25 cm and minimum was 1.16 cm. The mean anteroposterior diameter of trachea was 1.70 cm. The maximum transverse diameter of trachea was 2.1 cm and minimum was 1.42 cm. The mean transverse diameter of trachea was 1.78 cm. Conclusion: Knowledge of the diameter and length of the trachea is essential in the proper selection of endotracheal tube size used for delivery of anaesthetic gases during general anaesthesia. In addition, this knowledge aids clinicians in choosing the proper size of tracheostomy tubes used in emergency situations. Key words: Trachea, Luminal cast Plastination, Tracheobronchial tree cast

Spatial orientation and mechanical properties of the human trachea: a computed tomography study.

The literature generally describes the trachea as oriented toward the right and back, but there is very little detailed characterization. Therefore, the aim of this study was to precisely determine the spatial orientation and to better characterize the physical properties of the human trachea. We analyzed lung computed tomography scans of 68 intubated and mechanically ventilated subjects suffering from acute lung injury/ARDS at airway pressures (Paw) of 5, 15, and 45 cm H2O. At each Paw, the inner edge of the trachea from the subglottal space to the carina was captured. Tracheal length and diameter were measured. Tracheal orientation and compliance were estimated from processing barycenter and surface tracheal sections. Tracheal orientation at a Paw of 5 cm H2O showed a 4.2 ± 5.3° angle toward the right and a 20.6 ± 6.9° angle downward toward the back, which decreased significantly while increasing Paw (19.4 ± 6.9° at 15 cm H2O and 17.1 ± 6.8° at 45 cm H2O, P < .001). Tracheal compliance was 0.0113 ± 0.0131 mL/cm H2O/cm of trachea length from 5 to 15 cm H2O and 0.004 ± 0.0041 mL/cm H2O/cm of trachea length from 15 to 45 cm H2O (P < .001). Tracheal diameter was 19.6 ± 3.4 mm on the medial-lateral axis and 21.0 ± 4.3 mm on the sternal-vertebral axis. The trachea is oriented downward toward the back at a 20.6 ± 6.9° angle and slightly toward the right at a 4.2 ± 5.3° angle. Understanding tracheal orientation may help in enhancing postural drainage and respiratory physiotherapy, and knowing the physical properties of the trachea may aid in endotracheal tube cuff design.

Migrate small, sound big: functional constraints on body size promote tracheal elongation in cranes.

Organismal traits often represent the outcome of opposing selection pressures. Although social or sexual selection can cause the evolution of traits that constrain function or survival (e.g. ornamental feathers), it is unclear how the strength and direction of selection respond to ecological shifts that increase the severity of the constraint. For example, reduced body size might evolve by natural selection to enhance flight performance in migratory birds, but social or sexual selection favouring large body size may provide a countervailing force. Tracheal elongation is a potential outcome of these opposing pressures because it allows birds to convey an auditory signal of exaggerated body size. We predicted that the evolution of migration in cranes has coincided with a reduction in body size and a concomitant intensification of social or sexual selection for apparent large body size via tracheal elongation. We used a phylogenetic comparative approach to examine the relationships among migration distance, body mass and trachea length in cranes. As predicted, we found that migration distance correlated negatively with body size and positively with proportional trachea length. This result was consistent with our hypothesis that evolutionary reductions in body size led to intensified selection for trachea length. The most likely ultimate causes of intensified positive selection on trachea length are the direct benefits of conveying a large body size in intraspecific contests for mates and territories. We conclude that the strength of social or sexual selection on crane body size is linked to the degree of functional constraint.

Use of nitinol self-expandable stents in 26 dogs with tracheal collapse

A study was designed to describe a novel approach to the treatment of tracheal collapse (TC) in dogs using self-expandable nitinol stents. Medical records were reviewed retrospectively for 26 client owned dogs in which nitinol stents were deployed. The entire length of trachea was supported independently of the extent of TC. Two overlapping stents were used instead of one in cases where one stent was not spanning the entire trachea adequately. The diameter of the cranial radiolucent portion of trachea, just behind the cricoid cartilage, was measured as a specific landmark to select the appropriate size of the stent. Two self-expandable nitinol stents were inserted in 9 of 26 dogs; the trachea in the rest of the cases was supported with only one stent. A follow up tracheoscopy was performed in 10 of 26 cases with recurrent clinical signs. Secondary tracheal stenosis in these cases was caused by stent fracture, granuloma or excessive stent shortening. Additional stents were placed successfully to expand the stenotic lumen. A support of the entire trachea may decrease risk of nitinol fracture at the end of the implant. Long term clinical improvement (25 of 26 dogs, 96 %) is comparable with the results of other studies.

Detection of airway ischaemic damage after lung transplantation by using autofluorescence imaging bronchoscopy

Airway complications related to ischaemia are a major cause of morbidity after lung transplantation. Early detection of airway ischaemia and optimal management of the anastomotic site could reduce the risk of airway complications. Autofluorescence imaging (AFI) bronchoscopy has been increasingly recognized as an effective technique for detecting abnormal mucosal thickening. The aim of this study was to investigate whether AFI bronchoscopy can facilitate the detection of airway ischaemic damage in lung transplant patients. Twenty Landrace pigs were used to create a tracheal autotransplantation model. A four-ring length of trachea was excised and implanted orthotopically. The tracheal autograft was observed on postoperative days 0, 2, 4 and 7 with AFI bronchoscopy. The extent and origin of graft autofluorescence were examined using histology and measured according to fluorescence intensity. The lesions on the tracheal autografts appeared as bright green fluorescence on AFI bronchoscopy. On confocal fluorescence microscopy, high-intensity green fluorescence was observed in the elastin fibre layer of the submucosa. The fluorescence intensity of elastin was significantly higher in the graft showing fluorescence than the graft that did not show fluorescence and that at the control site. Bright green fluorescence was seen in an elastin fibre layer in the submucosa, which was likely a result of epithelial sloughing. There is a close relationship between the bright green fluorescence pattern observed using AFI bronchoscopy and airway ischaemic damage. We conclude that AFI bronchoscopy may detect airway ischaemic damage after lung transplantation.

Lower airway anomalies in children with CATCH 22 syndrome and congenital heart disease

CATCH 22 syndrome is a medical acronym for multiple abnormalities, especially cardiac defect. The patients with congenital heart disease (CHD) usually have more complicated post-surgery course. We reviewed 4-year experience in our hospital to define the lower airway anomalies and the clinical implications in patients with CATCH 22 syndrome and CHD. From 2004 to 2007, 18 patients who underwent computed tomography for planning of cardiovascular treatment were enrolled. Detection of airway anomalies were performed on computed tomography. Characteristic dysmorphic facial features were noted in 8 out of 18 patients (44%). Ten patients (55.6%) had mild to moderate tracheal or bronchial stenosis. Five patients (28%) had tracheomalacia or bronchomalacia. Comparing to control group, patients received the first major surgery with a median hospital stays of 42 days in study group had a significantly longer hospital stay (42 vs. 16, P = 0.005) and longer duration of ventilator usage (16 vs. 4, P = 0.014). The difference of the mean position of the carina on computed tomography image between study groups and control groups was about three-quarters of a vertebral body height (P < 0.05). Patients with CATCH 22 syndrome and CHD had a shorter length of trachea compared to that of the age-matched similar CHD. The incidence of associated lower airway anomalies in CHD children with CATCH 22 syndrome was higher. It may lead to longer time of ventilator support after surgery as well as total hospital stays than those of CHD without CATCH 22 syndrome.

Three-dimensional Airway Tree Architecture and Pulmonary Function

The airway tree is a primary conductive structure, and airways' morphologic characteristics, or variations thereof, may have an impact on airflow, thereby affecting pulmonary function. The objective of this study was to investigate the correlation between airway tree architecture, as depicted on computed tomography, and pulmonary function. A total of 548 chest computed tomographic examinations acquired on different patients at full inspiration were included in this study. The patients were enrolled in a study of chronic obstructive pulmonary disease (Specialized Center for Clinically Oriented Research) and underwent pulmonary function testing in addition to computed tomographic examinations. A fully automated airway tree segmentation algorithm was used to extract the three-dimensional airway tree from each examination. Using a skeletonization algorithm, airway tree volume-normalized architectural measures, including total airway length, branch count, and trachea length, were computed. Correlations between airway tree measurements with pulmonary function testing parameters and chronic obstructive pulmonary disease severity in terms of the Global Initiative for Obstructive Lung Disease classification were computed using Spearman's rank correlations. Non-normalized total airway volume and trachea length were associated (P < .01) with lung capacity measures (ie, functional residual capacity, total lung capacity, inspiratory capacity, vital capacity, residual volume, and forced expiratory vital capacity). Spearman's correlation coefficients ranged from 0.27 to 0.55 (P < .01). With the exception of trachea length, all normalized architecture-based measures (ie, total airway volume, total airway length, and total branch count) had statistically significant associations with the lung function measures (forced expiratory volume in 1 second and the ratio of forced expiratory volume in 1 second to forced expiratory vital capacity), and adjusted volume was associated with all three respiratory impedance measures (lung reactance at 5 Hz, lung resistance at 5 Hz, and lung resistance at 20 Hz), and adjusted branch count was associated with all respiratory impedance measures but lung resistance at 20 Hz. When normalized for lung volume, all airway architectural measures were statistically significantly associated with chronic obstructive pulmonary disease severity, with Spearman's correlation coefficients ranging from -0.338 to -0.546 (P < .01). Despite the large variability in anatomic characteristics of the airway tree across subjects, architecture-based measures demonstrated statistically significant associations (P < .01) with nearly all pulmonary function testing measures, as well as with disease severity.

The displacement of the tracheal tube during robot-assisted radical prostatectomy

Robot-assisted prostatectomy requires pneumoperitoneum in a steep Trendelenburg position, which may induce endobronchial intubation or accidental extubation. The aim of the study was to evaluate the effect of pneumoperitoneum in 30 degrees Trendelenburg position on the displacement of the tracheal tube and to measure the changes in trachea length using fiberoptic bronchoscope. Thirty male patients scheduled for robot-assisted radical prostatectomy were enrolled. After induction of general anaesthesia, the distance between the vocal cords and the tracheal tube tip (DeltaVE), between the tracheal tube tip and the carina (DeltaEC) and between the vocal cords and the carina (DeltaVC) was measured using a fiberoptic bronchoscope before and 10 min after pneumoperitoneum in neutral position (T1 and T2, respectively), and 2 h after pneumoperitoneum in 30 degrees Trendelenburg position (T3). The DeltaVC and DeltaEC decreased significantly 10 min after pneumoperitoneum in neutral position (T2) and 2 h after pneumoperitoneum in Trendelenburg position (T3) compared with those before pneumoperitoneum in neutral position (T1) (all P < 0.001). The changes in DeltaVE were not statistically significant. The confirmation of the tracheal tube position is recommended after pneumoperitoneum in steep Trendelenburg position during robot-assisted prostatectomy because the displacement of the tracheal tube may result in endobronchial intubation due to shortening of the carina-to-tube tip distance.

Clinically Correlated Anatomical Basis of Cricothyrotomy and Tracheostomy

Cricothyrotomy and tracheostomy are performed by physicians in various disciplines. It is important to know the comprehensive anatomy of the laryngotracheal region. Hemorrhage, esophageal injury, recurrent laryngeal nerve injury, pneumothorax, hemothorax, false passage of the tube and tracheal stenosis after decannulation are well known complications of the cricothyrotomy and tracheostomy. Cricothyrotomy and tracheostomy should be performed without complications and as quickly as possible with regards the patients' clinical condition. A total of 40 cadaver necks were dissected in this study. The trachea and larynx and the relationship between the trachea and larynx and the surrounding structures was investigated. The tracheal cartilages and annular ligaments were counted and the relationship between tracheal cartilages and the thyroid gland and vascular structures was investigated. We performed cricothyrotomy and tracheostomy in eleven cadavers while simulating intensive care unit conditions to determine the duration of those procedures. There were 11 tracheal cartilages and 10 annular ligaments between the cricoid cartilage and sternal notch. The average length of trachea between the cricoid cartilage and the suprasternal notch was 6.9 to 8.2 cm. The cricothyroid muscle and cricothyroid ligament were observed and dissected and no vital anatomic structure detected. The average length and width of the cricothyroid ligament was 8 to 12 mm and 8 to 10 mm, respectively. There was a statistically significant difference between the surgical time required for cricothyrotomy and tracheostomy (p < 0.0001). Tracheostomy and cricothyrotomy have a low complication rate if the person performing the procedure has thorough knowledge of the neck anatomy. The choice of tracheostomy or cricothyrotomy to establish an airway depends on the patients' clinical condition, for instance; cricothyrotomy should be preferred in patients with cervicothoracal injury or dislocation who suffer from respiratory dysfunction. Furthermore; if a patient is under risk of hypoxia or anoxia due to a difficult airway, cricothyrotomy should be preferred rather than tracheostomy.

Effect of head posture on pediatric oropharyngeal structures: implications for airway management in infants and children

Although head and neck posture has direct effects on the upper airway in infants and children, many of these effects remain unclear or not well established. As airway patency and airway access are critical in sedated and/or unconscious children, recent developments in this area should be made known to pediatric anesthesiologists, intensive care physicians and other emergency caregivers. All recent studies observed large interindividual variability in anatomical measurements, especially in trachea length. More evidence has been gained that lateral position improves upper airway patency in sedated children. Several studies brought indirect information on head posture for laryngoscopy and intubation. The site of obstruction of the airway in sedated children in different postures is now more clear. Implications of head flexion and extension in intubated children have been extensively studied, and clinical consequences have been detailed. Due to large interindividual anatomic variability, depth marks set on the tubes by their manufacturers and guidelines regarding calculations of insertion depth should be made with caution in infants and neonates. Despite several studies, there is still little scientific evidence regarding proper head posture for laryngoscopy and intubation.

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.

Dimorfismo sexual da traquéia e siringe de periquito (Touist sp.)

Investigaram-se as diferenças morfológicas da siringe do periquito Touist sp, cinco machos e cinco fêmeas. A traquéia e a siringe foram dissecadas com o auxílio de uma lupa estereoscópia e avaliaram-se o número de anéis, o comprimento da traquéia e da siringe e o comprimento e espessura do músculo traqueolateral. A traquéia do macho apresentou maior número de anéis e maior comprimento que a das fêmeas. O músculo traqueolateral dos machos é mais vigoroso e origina-se no 43º anel traqueal enquanto o das fêmeas origina-se no 30º anel traqueal e se insere no primeiro anel bronquial. A siringe do piriquito é constituída por anéis craniais, cinco nos machos e três nas fêmeas, anéis intermediários, com formato semelhante a uma bolha sulcada ventralmente, anéis caudais, quatro em ambos os sexos, e pessulo. O dimorfismo sexual está presente na morfometria da musculatura e das cartilagens, o que reflete no canto mais vigoroso dos machos.

An Unusual Experience During Percutaneous Dilatational Tracheostomy

We reported a case of repeated misplacement of tracheostomy tube following percutaneous dilatational tracheostomy in a patient of thyroid swelling. An endotracheal tube was inserted through stoma as the former was falling short in comparison to increased skin to trachea length.

Dilatation for Assisted Ventilation‐Induced Laryngotracheal Stenosis

To assess the long-term results of dilatation and our experience with dilatation for assisted ventilation-induced laryngotracheal stenosis. A retrospective study of 32 patients primarily treated with dilatation for assisted ventilation-induced laryngotracheal stenosis between 1977 and 2002. A tertiary care center and university teaching hospital. There were 19 men and 13 women aged 15 to 76 years. The stenosis was cicatricial with some inflammatory process in 27 patients and completely mature in 5 patients. The stenosis involved the cricoid and the trachea in four patients. In 28 patients, the stenosis involved only the trachea. Dilatation was performed with serially sized rigid bronchoscopes. Endoscopic laser vaporization was never performed in this series. Six patients were treated with only one dilatation. The 26 remaining patients were treated with successively 2 to 10 dilatations (mean, 3.3 dilatations). The dilatation success rate was analyzed using the Kaplan-Meier method. Median duration of follow-up was 1.8 years. Mortality rate was 9.4%. The overall failure rate was 71.8%. Twenty patients presented with recurrent stenosis. The treatment of recurrent stenosis consisted of tracheal resection with end-to-end anastomosis (11 patients, 55%), cricotracheal anastomosis (5 patients, 25%), tracheal endoprosthesis (2 patients, 10%), and tracheotomy (1 patient, 5%). All patients who underwent tracheal or cricotracheal anastomosis were successfully treated. None of the variables under analysis (sex, age, medical history, cause for intubation, intubation type and duration, delay from initial injury, degree of stenosis, length of trachea involved, number of dilatations) were statistically related to the incidence of complications and the success rate of dilatations. We do not recommend dilatation technique as the sole treatment for assisted ventilation-induced laryngotracheal stenosis. This technique is helpful in case of emergency to restore an airway and useful for the assessment of stenosis.

Tracheal resection with primary anastomosis in cadavers: the effects of releasing maneuvers and length of tracheal resection on tension.

To determine the relationships among length of trachea resected, total tracheal length, and anastomotic tension when using various release maneuvers, we studied 10 adult human cadavers: 5 male and 5 female. The trachea was transected between rings 2 and 3. Precision, handheld spring tensiometers (Geneva Gage, LLC) were used to measure the tension required to approximate, and then overlap, the proximal segment relative to the distal segment, and the distal segment relative to the proximal segment after these maneuvers: no release, blunt dissection, neck flexion, suprahyoid release (SHR) without neck flexion, SHR with neck flexion, and right hilar release. After the tension measurements were recorded, the trachea was harvested and the total tracheal length was measured. Length-tension curves were plotted for both the superior and inferior tracheal segments after each release maneuver. The stiffness coefficient for the trachea and the resting load on the trachea following each release maneuver were calculated. An exponential length-tension relationship existed for the distal tracheal segment regardless of whether release maneuvers were performed. The proximal tracheal segment exhibited a linear length-tension relationship initially, but displayed an exponential relationship after SHR. We could resect 6.68 cm (range, 4.2 to 9.9 cm), 13.3 rings (range, 10 to 20 rings), or 65.5% (range, 42% to 100%) of the trachea without undue tension (<1,000 g) on the anastomosis. We conclude that various tracheal release maneuvers are effective in increasing the length of trachea that can be relatively safely resected. However, these maneuvers are not uniformly effective across subjects.

A Successful Slide Cricotracheoplasty in Congenital Cricotracheal Stenosis

【Slide tracheoplasty. as a treatment for congenital tracheal stenosis, has been recently reported to have good results and quite a number of advantages as compared with conventional tracheoplasties. The aim of this study is to report a new surgical technique modified from slide tracheoplasty. the slide for congenital cricotracheal stenosis. A girl was born by Cesarean section and diagnosis of esophageal atresia (Gross type C) and cricotracheal stenosis (30 % of total length of trachea) was established. Esophageal atresia was successfully corrected at 8th day of life. At 31st day of life, corrective surgery for congenital cricotracheal stenosis. slide cricotracheoplasty. was performed with success. Slide cricotracheoplasty is almost same procedure as slide tracheoplasty except for two technical features. First cricoid cartilage was split on its anterior surface. Second split cricoid cartilage was fixed to pre vertebral fascia to maintain enough space to accommodate sliding caudal segment of trachea because of stiffness of cricoid cartilage. We believe that sliding cricotracheoplasty is a new surgical technique for congenital cricotracheal stenosis that has similar results and advantages as sliding tracheoplasty.】

Paediatric airway stenosis: laryngotracheal reconstruction or cricotracheal resection?

Modern surgical management of paediatric laryngotracheal stenosis includes a wide variety of surgical procedures. These can broadly be divided into two groups. First, laryngotracheal reconstruction (LTR) procedures in which the cricoid cartilage is split and the framework is expanded with various combinations of cartilage grafts and stents; and second, cricotracheal resection (CTR) where a segmental excision of the stenotic segment is done and an end-to-end anastomosis is performed. In this article we review the literature and our experience and discuss the relative indications for CTR and LTR in children. High decannulation rates have been reported for CTR; however, it remains a more extensive procedure than LTR involving extensive tracheal mobilization. If the tracheostomy site is included in the resection then a significant length of trachea is excised. Alternatively, LTR with cartilage grafting can precisely correct a specific stenosis with minimum morbidity and high decannulation rates for grade 2 and selected grade 3 stenosis. For the more severe stenosis treatment with LTR has been less successful. Retrospective data from this institution suggests that the children with grade 4 stenosis treated with LTR are more likely to require a subsequent open procedure to achieve decannulation than those treated with CTR. LTR is a less extensive procedure and is preferred for grade 2, selected grade 3 stenosis. CTR is the preferred option for grade 4 and severe grade 3 stenosis with a clear margin between the stenosis and the vocal cords.

Perceptual and acoustic analysis of vocal registers in 10-year-old children

Register transitions were identified by a group of five experts on child voices in recordings of 15 10-year-old children who sustained the vowel [a:] at different pitches throughout their vocal range. Two had mutational voices, seven had deviant voices and six were controls with normal voices. The control group had one register transition at a mean fundamental frequency of 511 Hz, or about 25% higher than in adult voices. This difference between adult and child voices may be because of the difference in trachea length, as proposed by Titze (J. Voice 1988; 3: 183-194). Children with either functional or physiological voice deviations exhibited a transition at a mean frequency of 417 Hz. A second transition was found in four voices at a mean frequency of 902 Hz. No correlation was found between the occurrence of register transitions and discontinuities in the upper and lower voice range profile contours.

Acoustic exaggeration of size in birds via tracheal elongation: comparative and theoretical analyses

AbstractAt least 60 bird species possess an elongated trachea that typically forms loops or coils within the sternum or thorax. This peculiar trait has been known for centuries, and a wide variety of hypotheses have been proposed for its function. However, none of these hypotheses adequately accounts for its existence in all of the diverse bird species and habitats in which it is found. In this paper it is proposed that tracheal elongation serves to exaggerate the apparent size of a vocalizing bird. In normal birds, trachea length is correlated with body size, and thus the acoustic correlates of trachea length in bird calls could convey information about size. By manipulating such an acoustic cue (formant frequency dispersion), tracheal elongation allows a caller to duplicate sounds produced by a larger bird. Unlike previously‐proposed hypotheses, this ‘size exaggeration’ hypothesis is found to be consistent with current theories of avian vocal production and a wide range of comparative ecological and behavioural data. A number of new predictions of the hypothesis are found to be upheld. Finally, tracheal elongation is considered as a possible example of ‘sensory exploitation’, and its ultimate functional significance in mate choice and/or territoriality is discussed.

Tracheal transplantation: Defining the vascular territory of the canine cranial thyroid artery

The management of long-segment tracheal stenosis remains an unsolved clinical problem that has significant implications for the survival of some patients and the quality of life of others. However, recent advances in microvascular tissue transfer may allow tracheal transplantation to be used as a treatment option. Studies in dogs have demonstrated that the reanastomosis of the cranial thyroid artery (CTA) after the transplantation of a short segment of trachea sustains cartilage viability. However, the distal perfusion zone of the CTA within the canine trachea has not been described. Hence it is unclear what length of trachea can be safely harvested, with use of the CTA as the donor artery, without risking ischemia of the distal trachea. This study determined the perfusion territory of the CTA by use of latex or dye infusion via the thyroid branches of the CTA. Findings in five perfusion-fixed cadaver mongrel dogs (8 to 12 kg) were studied. In each dog, both common carotid arteries were dissected and the CTAs identified. The right CTA was ligated and the left common carotid artery was ligated cranial to the CTA. The left common carotid artery was perfused for 10 minutes under 100 mm Hg pressure with black india ink/saline solution (20:1000 ml) or with blue latex solution. Perfusion territories were determined by grossly and microscopically measuring the region of stain in the endolaryngeal and endotracheal airways. The results demonstrated that up to 18 ipsilateral rings of the canine trachea are perfused after injection of dye under physiologic pressure into the CTA. Contralateral staining was also noted, but to a lesser degree. These results suggest that the canine CTA may perfuse, on average, a 16- to 17-ring tracheal segment. (Otolaryngol Head Neck Surg 1999;120:180-3.)