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General Surgery
Respiratory System
Built from Skandalakis' Surgical Anatomy: The Embryologic and Anatomic Basis of Modern Surgery
What’s inside
15 sections · 171 slides
Overview
- Embryogenesis of the trachea, bronchi and lungs, and the antenatal phases of lung growth Congenital anomalies: accessory lobes, agenesis, aplasia, hypoplasia, tracheal bronchus Surgical anatomy of trachea, bronchi and lungs with their topographic relations Bronchopulmonary segments, lung hila and the right and left bronchial trees Vascular supply, lymphatic drainage and innervation of the lower airway Operative applications: tracheostomy, resection, transplantation and their complications
Historical milestones
- The chapter opens with a dated table of anatomic and surgical landmarks It runs from Assyro-Babylonian descriptions of rhonchi to modern transplantation Useful for eponyms: Boyden's segmental nomenclature, Galen's thoracic physiology Read it for provenance of terms you already use, not for examinable detail
- Anatomic and Surgical History of the Respiratory System
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
- Anatomic and Surgical History of the Respiratory System (continued)
Embryogenesis
- Fourth week: an opening appears on the ventral pharyngeal wall of the foregut This is the laryngotracheal groove, the primordium of the lower respiratory system The groove grows out as the respiratory diverticulum, which yields respiratory epithelium The diverticulum carries mesenchyme with it as it enlarges Mesenchyme supplies connective tissue, muscle and cartilage for larynx, trachea and lungs
- Separation of the foregut into airway and oesophagus
- Division of the foregut into trachea and oesophagus
- 26 days after fertilisation the tracheal end of the diverticulum produces two lung buds The bronchial buds enlarge into the primordia of the right and left bronchi Right bronchus takes a caudal pathway; the left takes an oblique one Fifth week: two lateral buds arise on the right bronchus but only one on the left Both events are asymmetrical, and set up three right lobes against two on the left Within the lung bud the bronchial tree subdivides into blind ends, the infundibula
- Lung buds at the end of the fifth week
- Trachea and bronchi at the beginning of the seventh week
- Lobe segmentation continues until there are 10 segments on the right and 8 on the left Pulmonary formation ceases around the end of the fifth week Three antenatal phases of ramification then begin in sequence These are the glandular (pseudoglandular), canalicular, and alveolar (terminal sac) phases
- The three antenatal phases of lung development
- Pseudoglandular: solid cuboidal epithelial clusters surround each infundibulum The parenchyma histologically resembles an exocrine gland, hence the name Gas exchange is impossible, so a fetus born in this phase cannot survive Canalicular: blood vessels ramify around infundibula and alveolar primordia Pulmonary tissue becomes very vascular; bronchioles have enlarged laminae Respiration at 24-25 weeks is possible and the fetus may survive
- Runs from week 24-26 until birth, overlapping the end of the canalicular phase Terminal sacs multiply and their epithelium becomes thin and flat Rich proliferation of blood capillaries and lymph capillaries accompanies this Alveolar epithelial cells are type I pneumocytes Type II pneumocytes are the secretory cells that produce surfactant Surfactant coats the terminal sacs, lowering surface tension and preventing collapse
- Survival requires both adequate pulmonary vasculature and surfactant A premature seven-month fetus may survive: respiratory function is by then reasonable The lungs have some secretory function at this stage Surfactant promotes maturity of the antenatal lungs
- Postnatal alveolar multiplication
- During the first week air inflates all the alveoli Blood and lymphatic capillaries absorb the fluid that occupied 50% of the lung Rapid alveolar development runs from the sixth through the eighth week More alveoli continue to form during the first postnatal years
Congenital anomalies
- The chapter tabulates each anomaly with its prenatal age at onset It also gives first appearance or diagnostic clue, sex chiefly affected and relative frequency Onset ranges from week 3-4 for tracheal atresia to month 5 for tracheobronchomegaly Frequency and lethality vary from fatal at birth to incidental in adult life
- Congenital Anomalies of the Trachea and Lungs
- Congenital anomalies of the trachea and lungs
- Shields lists posterior accessory, inferior accessory, middle lobe of the left lung, azygos lobe Posterior, inferior and left middle lobes are true accessory lobes The azygos lobe is not truly accessory It is a partial separation of part of the apical segment of the right upper lobe The separating structure is the azygos venous arch Terminology in the literature is inconsistent, so define the term you are using
- Accessory lobes of the lungs
- Formed by a deep indentation from an aberrant tributary of the azygos vein The mesoazygos is the accompanying fold of parietal pleura carried down with the vein It lies in the region of the apical and posterior segments of the right upper lobe It varies considerably in size and extent Anson's figures record an incidence of 0.4%, that is 8 cases in 2000 specimens
- Azygos lobe and the anomalous azygos vein
- Defined by an aberrant fissure running horizontally on the costal surface of the lower lobe Matawari found 19 cases in 273 specimens: 13% on the right, 3% on the left It frequently corresponded to S6, the superior segment: right 87%, left 50% B7 (medial basal) tended to form a common trunk with B (subsuperior) or B8 (anterior basal) V6 tributaries were often double and V6 tended to disperse widely Anomalous segmental artery or vein communicating with other segments in 7 of 19 cases (37%)
- Congenital deficiency of lung tissue
- Pulmonary aplasia and dysplasia compared with normal lungs
- Pulmonary hypoplasia and pulmonary ectoplasia
- The right upper lobe bronchus originates from the lateral tracheal wall Peragallo and Swenson report it in approximately 1 in 250 patients at bronchoscopy It is usually of little clinical significance in itself The atypical origin may complicate one-lung ventilation during thoracic surgery
- Roque reported unilateral right pulmonary agenesis without mediastinal displacement In that case there was cervical ascent of the liver and right hemidiaphragm Evrard: any expanding thoracic cystic lesion on radiography is an indication for resection Resect even if asymptomatic, given risks of compression, infection and malignant degeneration For a fetal intrathoracic mass, prenatal diagnosis and intrauterine intervention may be indicated Endo: congenital pulmonary venous obstruction causes reversible, operable pulmonary hypertension
The trachea
- Divided surgically into an upper (cervical) and a lower (thoracic) part with the bifurcation Supine length 10-13 cm, from the laryngotracheal junction at C6 to the bifurcation at T4 In upright posture the trachea lies between C6 and T6 Kubik and Healey: tracheal length may increase by about 1.5-2.5 cm on swallowing or respiration Mulliken and Grillo: with the neck flexed the trachea can lie wholly within the mediastinum Neck flexion drops the cricoid cartilage to the level of the thoracic inlet
- Origin of the trachea at the sixth cervical vertebra
- 15 to 20 U-shaped rings of hyaline cartilage give the trachea its lateral rigidity The rings are united by a thin elastic membrane Posteriorly the cartilages are united by the trachealis, a thin smooth muscle Position is not fixed: the trachea may deviate right or left It is ensheathed in loose connective tissue stroma also related to the oesophagus
- Kubik and Healey: the cervical trachea at its origin lies 1.5-2 cm below the skin At the sternal notch the trachea is 4.5-5.0 cm beneath the skin At the bifurcation the depth is approximately 7 cm The thoracic trachea is the deepest anatomic entity of the superior mediastinum
- Fascial layers of the neck and the danger space
- Bifurcation lies at the sternal angle anteriorly and the fifth thoracic vertebra posteriorly It sits just above the left atrium The carina is the internal ridge at the bifurcation, at the level of the last tracheal cartilage It separates the proximal ends of both bronchi and is a bronchoscopic landmark Also called the tracheal keel; it may be membranous or cartilaginous
- Schuster: a catheter tip inside the pericardium risks lethal cardiac tamponade The pericardium is not visible on chest radiography, so a surrogate marker is needed The carina was a mean 0.4 (SD 0.1) cm above the pericardial sac as it crosses the SVC In no case was the carina located below the pericardial sac The carina is visible even on poor quality portable films Catheter tips should lie in the superior vena cava above the level of the carina
- The thymic vessels
- Lower end of the trachea and the deep cardiac plexus
- Right vagus nerve
- Arteries: inferior thyroid arteries, with branches from superior thyroid, bronchial, internal thoracic Veins: inferior thyroid veins drain to one or both brachiocephalic veins Lymphatics drain to cervical, tracheal and tracheobronchial nodes Sympathetic postganglionic fibres from cardiac branches of the cervical trunk and thoracic visceral nerves Sympathetic supply to tracheal muscle is bronchodilator Parasympathetic fibres from vagus and recurrent laryngeal nerves are bronchoconstrictive
The bronchi
- Right and left primary bronchus compared
- Primary bronchi and their anterior vascular relations
- Ashour: the left lung is more vulnerable to bronchiectasis than the right The left main bronchus has a longer mediastinal course than the right It has a narrower diameter It has limited peribronchial space as it passes through the subaortic tunnel The left lung is more affected both in frequency and severity These features make the left main bronchus more prone to obstruction
- Left main bronchus in the subaortic tunnel
- Trotter: torsion of the whole lung or of a lobe may be spontaneous or follow trauma Felson listed the anatomic conditions that predispose to this rare event A 180 degree rotation can produce right or left lobar torsion in theatre or postoperatively Wong and Goldstraw reported this complication; lobopexy is occasionally necessary
- Origin of right and left bronchial arteries is very variable They may arise from internal thoracic, subclavian or inferior thyroid arteries Most commonly a single right bronchial artery arises from the aorta or 3rd right posterior intercostal artery The left lung is supplied by two bronchial arteries from the beginning of the descending thoracic aorta Carles: the supply is dominated by the intercostobronchial trunk and anastomotic networks Their findings on bronchial artery revascularisation may apply to pulmonary transplantation
- Sites of origin and number of the bronchial arteries
- Cauldwell's series dissected 150 autopsy specimens It records the number of right and left bronchial arteries with percentage incidence Read it as a probability distribution, not a normal pattern with exceptions The commonest single arrangement accounts for well under half of specimens
- Origins and Number of Bronchial Arteries in 150 Dissected Autopsy Specimens
- Variations in origin of the bronchial and oesophageal arteries
- Systemic blood supply to the lung
- Right bronchial veins, usually two, drain to the terminal part of the azygos vein Left bronchial veins end in the left superior intercostal vein or the accessory hemiazygos Lymphatic vessels from the bronchi pass to bronchopulmonary and tracheobronchial nodes Sympathetic and parasympathetic innervation via the pulmonary and cardiac plexuses The bronchi are relatively insensitive to pain Stimulation of the bronchial mucosal lining produces coughing
- Right bronchial veins
- Main veins of the thorax
- Regional drainage of the pulmonary lymphatics
The lungs: topography and relations
- The lungs are movable within the thoracic cavity but anchored to the heart and trachea Right lung: three lobes. Left lung: two lobes The right lung is shorter because of the right hepatic lobe The left lung is narrower because of the leftward position of the heart and pericardium Each lung receives the bronchi and the pulmonary vessels Both have an apex, a base, three surfaces, three borders and fissures
- Coronal section of the thorax through the tracheal bifurcation
- Coronal section of the thorax through the heart and great vessels
- Covered by pleura and projecting above the clavicle into the root of the neck Extent above the clavicle varies with respiration, posture, body build and angle of view The apex of the left lung is a little longer than that of the right The surgeon must remember the upward cervical projection of the lung
- The base rests on the superior surface of the diaphragm and relates to subdiaphragmatic organs Right lower lobe: pleura, diaphragm, peritoneum, right lobe of liver Left lower lobe: pleura, diaphragm, peritoneum, left lobe of liver, gastric fundus, spleen Costal surface relates to the thoracic wall and ends at the three pulmonary borders Medial (mediastinal) surface contacts mediastinal organs; posteriorly it relates to the spine The hilum, or pulmonary porta, transmits bronchi, vessels and nerves
- Relationships between the lungs and the mediastinal organs
- Frija studied the inferior lung margin (ILM) using computed radiography Right posterior ILM always visible, usually concave upward (94%), height 8.7 (SD 1.6) cm Its most inferior part faced L1 or L2 in 92% and was continuous with the azygo-oesophageal recess in 96% Left posterior ILM not visible laterally in 34% and medially in 60%; height 6.9 (SD 1.5) cm Right anterior ILM visible in 76%, often oblique upward and medially or concave upward, notched in 38% Anterior margins are more variable than posterior; posterior margins differ mainly in diaphragmatic height
- Anterior, inferior and posterior borders correspond to the lines of pleural reflection Borders are atypical and not always constant; deep or shallow respiration changes their topography Left oblique fissure begins posteriorly at the 4th rib, occasionally 3rd or 5th, ending at the 6th or 7th Right oblique fissure begins at about the 5th rib and ends at the 6th costochondral junction Both oblique fissures cross the midaxillary line at the level of the 5th or 6th rib The horizontal fissure runs from the 6th rib in the midaxillary line to the 4th costal cartilage
- Borders of the pleurae and lungs, anterior and posterior views
- Borders of the pleurae and lungs, lateral views
- External fissures of the lungs and how often they occur
Bronchopulmonary segments
- A bronchopulmonary segment is the portion of lung served by a tertiary bronchus Right lung has 10 segments, left lung has 8 Some writers count the two terminal branches of the apicoposterior segment separately They also split the anteromedial basal segment, thereby giving the left lung 10 segments Each segment has a centrally placed bronchus and a branch of the pulmonary artery Pulmonary venous tributaries run between the segments, not within them
- The bronchopulmonary segments
- The table pairs each segment name with its numerical designation on each side Bracketed numbers give the alternative numbering used in the literature Left-sided fusions are shown as combined numbers, for example apicoposterior as 1 + 3 Use it to translate between an operation note and an atlas that number segments differently
- Bronchopulmonary Segmental Nomenclature and Numerical Designations
- Bronchopulmonary Segmental Nomenclature and Numerical Designations (continued)
- Three lobes defined by an oblique major fissure and a horizontal minor fissure The oblique fissure separates the lower lobe from the middle lobe The horizontal fissure separates the upper lobe from the middle lobe Upper lobe: apical, posterior and anterior segments Middle lobe: medial and lateral segments Lower lobe: superior segment plus anterior, medial, posterior and lateral basal segments
- Two lobes separated by the oblique fissure Apical and posterior segments of the upper lobe fuse as the apicoposterior segment Medial basal and anterior basal share a common origin as the anteromedial segment The lingula is the inferior part of the left upper lobe, a thin prolongation in front of the heart It contains superior and inferior lingular segments and relates to the left 6th rib and left ventricle The lingula is the homologue of the right middle lobe
- Each segment is an independent and separate surgical unit It can be excised in toto because anastomosis between adjacent segments is minimal Segmental veins lie between segments and are good landmarks for intersegmental separation Apicoposterior segments of the upper lobes are common sites for tuberculosis Superior segments of the lower lobes are also common sites for tuberculosis Fissures may be absent or poorly developed, especially the horizontal fissure
Lung roots and hila
- The hilum is the area of the mediastinal surface transmitting bronchi and pulmonary vessels The lung root is the group of structures entering and leaving the hilum The two sides differ in lobe number, segment arrangement and topographic relations Knowledge of those differences is essential before approaching either hilum
- Approaches to the right lung hilum
- Approaches to the right lung hilum
- Approaches to the left lung hilum
- Approaches to the left lung hilum
The bronchial trees
- Right upper lobe bronchus is 1-1.5 cm long, from the lateral wall of the right main bronchus It arises below the carina and gives three segmental bronchi: apical, posterior, anterior Their genesis is variable; they probably form by trifurcation of the upper lobe bronchus The middle lobe bronchus arises perhaps 1 cm below the orifice of the upper lobe Its lateral and medial segments are formed by bifurcation The lower lobe bronchus gives five segmental bronchi: superior and four basal
- Right bronchial tree
- Tracheal bronchus supplying the apical segment of the right upper lobe
- Segmental bronchi of the right lung
- Left upper lobe bronchus arises anterolaterally about 5 cm distal to the carina It divides into an ascending superior and a descending inferior division The superior division bifurcates into apicoposterior and anterior bronchi The inferior division is the lingula, dividing into superior and inferior lingular bronchi Left lower lobe bronchus gives the superior segmental bronchus about 0.5 cm below the upper orifice The four remaining basal bronchi form by bifurcation and trifurcation, commonly anteromedial basal
- Left bronchial tree
- Segmental bronchi of the left lung
- Typical branchings of the chief bronchi of the left lung
Pulmonary vessels
- The dual blood supply of the lung
- Right and left pulmonary arteries arise from the pulmonary trunk, itself from the right ventricle The trunk has an intrapericardial part 3.75 cm long and an extrapericardial part 1.25 cm long The extrapericardial portion lies to the left of the ascending aorta The trunk bifurcates in the concavity of the aortic arch, below the trachea The bifurcation lies in front of the left main bronchus It gives a right pulmonary artery closely related to the ascending aorta and a short left artery
- The right pulmonary artery is longer and larger than the left It lies below the carina and anterior to the right main bronchus Its anterior relations are the ascending aorta, superior vena cava and phrenic nerve At the root the right bronchus lies above it and the pulmonary veins below The left pulmonary artery is attached to the aortic arch concavity by the ligamentum arteriosum It crosses over the left primary bronchus behind the upper lobe bronchus
- Pulmonary arteries and segmental arteries
- Common branching pattern of the right and left pulmonary arteries
- Pulmonary veins are highly variable and contain no valves There are usually two on each side, superior and inferior They are formed by intersegmental tributaries and do not follow the bronchi closely Right superior vein lies anterior, occasionally inferior, to the right pulmonary artery It has four tributaries: three from the upper lobe and one from the middle lobe Right inferior pulmonary vein lies inferior and posterior to the superior vein
- The left superior pulmonary vein is formed by three or four branches These drain the left upper lobe in its entirety It lies roughly anterior to the left pulmonary artery The left inferior pulmonary vein is formed by two branches It lies inferior and posterior to the superior vein
- Pulmonary veins and segmental veins
Lymphatics, innervation and histology
- Pulmonary lymphatics belong to the greater group of thoracic lymphatics They intercommunicate richly and their node groups also communicate with each other Several competing classifications exist, confusing to student and surgeon alike Superficial group: lymphatics under the visceral pleura and in the interlobar septa Deep group: lymphatics around the vessels and bronchi Rich communication between the two networks occurs in the hilar area
- Schematic of the respiratory lymphatic system
- The chapter tabulates node positions separately for the right and left lungs Positions are given relative to lobar and segmental bronchial orifices Use it to name the station you are sampling in operative terms It complements, rather than replaces, the numbered staging maps
- Distribution of Bronchopulmonary Lymph Nodes
- Distribution of Bronchopulmonary Lymph Nodes (continued)
- Postganglionic fibres arise from the first five thoracic sympathetic ganglia They supply blood vessels, glands and the smooth muscle of the bronchi Their purpose is uncertain; they perhaps inhibit the action of smooth muscle Rosse and Gaddum-Rosse: visceral efferents are motor to bronchial glands They also produce vasoconstriction of pulmonary blood vessels Whether such fibres terminate on bronchiolar muscle is questioned, despite sympathomimetic bronchodilation
- Vagal fibres synapse on intrapulmonary ganglion cells whose axons supply the lung The vagus is motor to bronchial and bronchiolar smooth muscle and produces bronchoconstriction It most likely does not innervate smooth muscle in the wall of the pulmonary vessels Sensory vagal fibres probably affect the pulmonary vessels Vagal afferents may cause severe hypotension and changes in heart rate Vagal sensory fibres innervate the bronchial mucosa and mediate the cough reflex
- Parietal pleura is a somatic structure with generous somatic sensory innervation It is supplied by the intercostal and phrenic nerves, mediating touch and pain Irritation of mediastinal and medial diaphragmatic parietal pleura may refer pain Pain is referred to the root of the neck and over the shoulder The mechanism is overlap of cord segments for the phrenic nerve (C3-C5) and supraclavicular nerves (C3, C4) Visceral pleura is innervated by vagal fibres and mediates no pain
- The histologic features of trachea and bronchi are practically the same The wall is described in four layers from within outwards The innermost is mucous membrane with ciliated pseudostratified columnar epithelium Beneath it lies the lamina propria The chapter does not cover respiratory mechanics, ventilation or pulmonary blood flow
Surgical applications
- Common tracheal procedures: tracheostomy, tracheal resection, treatment of stenosis and of fistula The arch of the aorta begins anterior to the trachea, then lies above the left main bronchus The brachiocephalic artery lies in front of the trachea and then to its right The left common carotid artery lies anterior to the trachea and then passes to its left Tracheal deviation results from pressure in the neck or mediastinum The carina is the internal keel separating the two bronchial orifices, a bronchoscopic landmark
- Penetrating wounds of neck and chest can involve cervical or thoracic trachea They may involve one or both bronchi Blunt chest trauma can produce severe injuries of the trachea or bronchi The mechanism is the various forces generated during impact
- The usual site is between the second and fourth tracheal rings Layers: skin and superficial fascia, investing layer of deep cervical fascia, visceral compartment The visceral compartment lies under the pretracheal fascia Platysma lies in the superficial fascia but is absent in the midline Anterior jugular veins may lie close to the midline They may be united by a jugular venous arch at the level of the seventh to eighth tracheal rings
- Structures at risk during tracheostomy
- The isthmus commonly lies over the second and third tracheal rings It is often more cranial and less often more caudal In about 10 percent of individuals the two lobes are not connected by an isthmus The isthmus can be retracted up or down, or ligated and divided if necessary A thyroid ima artery is present in about 10 percent of individuals A suspensory ligament of the thyroid and a levator thyroid muscle may lie near the midline
- They arise as a venous plexus on the anterior surface of the thyroid isthmus Left and right descending veins enter the respective brachiocephalic veins The two veins may form a common trunk entering the SVC or the left brachiocephalic vein The inferior thyroid vein is often asymmetric and therefore more liable to injury The thyroid venous plexus over the gland drains into the thyroid veins
- Venous drainage of the thyroid gland
- Tracheostomy in children remains controversial because of possible complications Rocha considered the risks of tracheostomy and intubation acceptable in comatose children That applies to children needing prolonged ventilatory support Tepas, in editorial comment, questioned the necessity of early tracheostomy Bronchial stump should be covered with tissue such as pleura, muscle or omentum Coverage aids healing and avoids air leaks and bronchopleural fistula
- Bronchoscopy, biopsy, segmentectomy, lobectomy and partial lobectomy Total pneumonectomy and transplantation Choice is made according to the underlying pathology Fernando advises bronchial artery embolisation for haemoptysis Embolisation thereby reduces the need for lung resection
- McFadden and Robbins: video-assisted thoracoscopy may be used in selected patients Yim: safe and effective for pulmonary tuberculosis without chronic inflammation or distorted anatomy Liu: thoracoscopy is the treatment of choice for pneumothorax requiring surgery The lung can be approached by posterior or anterior thoracotomy, or median sternotomy Posterior thoracotomy is through the 5th intercostal space; anterior through the 3rd Asaph advocates median sternotomy for primary pulmonary carcinoma
- Key steps in total pulmonary resection
- Surgicoanatomic features are the same as those of pneumonectomy Air leaks should be treated by careful ligation of the small bronchi Rothenberg reported successful video-assisted thoracoscopic lung resection in infants and children Two patients with metastatic disease needing extensive resection were converted to thoracotomy
Anatomic complications
- Tracheostomy may be open, percutaneous or translaryngeal MacCallum: percutaneous and translaryngeal have fewer complications than open tracheostomy Escarment noted the convenience of percutaneous single-step dilatational tracheostomy The same authors urged further study of long term sequelae
- Superior and inferior thyroid artery branches may anastomose across the midline The cricothyroid branches are particularly liable to do so A thyroid ima artery is occasionally present and must be ligated if found Overly aggressive sharp dissection can injure the brachiocephalic artery Erosion by a tracheostomy tube can cause a tracheoarterial or tracheoesophageal fistula A wrongly curved or too low tube can compromise the subclavian artery
- Tracheostomy tubes and tube curvature
- Anterior jugular veins may be met when incising the investing fascia The brachiocephalic vein can be injured if sharp dissection is carried too far downward The left brachiocephalic (innominate) vein crosses high on the trachea The vein may be found just above the suprasternal notch, so it is particularly vulnerable The subclavian vein can be compromised by a wrongly curved or too low tube
- Oesophageal injury usually arises from errors of tube use, not misperceived anatomy Careless use and manipulation may cause a tracheoesophageal fistula Recurrent laryngeal nerve injury can occur during tracheostomy as during thyroidectomy Too high a tracheostomy can directly injure the vocal cords Placement through the thyrohyoid membrane can also produce vocal cord injury The stoma should be formed below the first ring
- Bonanno reported the adverse effect of a cuffed tube on the swallowing mechanism Trigeminal, glossopharyngeal, recurrent and external laryngeal nerves were evaluated Nerve injury was not a factor in the dysfunction The cause was inhibition of elevation and anterior rotation of the larynx There was also failure of the hypopharyngeal sphincter to open completely The distal end of an over-curved tube will erode the anterior tracheal wall (Roe: 60 degree curvature)
- Indicated for benign and malignant lesions of trachea, or trachea and bronchi Bronchoplastic procedures should be employed to allow pulmonary preservation Fahimi advised wedge carinal resection with rotational approximation for difficult stump closure Pilcher: delayed resection and reimplantation of an injured lobar bronchus is feasible Wood and Vallieres: 50 resections, no deaths, morbidity 32% Asamura found acceptable failure and bronchopleural fistula rates with newly developed endostaplers
- Tracheobronchial rupture may occur following intubation Jougon: aggressive surgical repair is not always mandatory after delayed diagnosis That applies to iatrogenic tracheobronchial rupture Conservative treatment must often be considered The stated exception is rupture occurring after lung resection
- Bleeding after lung resection
- Careful haemostasis of a bleeding intercostal artery may avert paraplegia Avoid cautery or packing at the posterior corner of the intercostal incision Dorsal branches of intercostal arteries, especially caudal ones, may give radicular branches to the cord Shama and Odell reported oesophageal injury of up to 0.5%; repair in theatre avoids fatal mediastinitis Vogt-Moykopf: contralateral pneumothorax 0.08%, most likely from a contralateral bleb Chylothorax 0.05% (Simpson) or 0.3% (Brie); the thoracic duct can be ligated with impunity
- A 180 degree rotation can produce right or left lobar torsion, in theatre or postoperatively Wong and Goldstraw reported it; lobopexy is occasionally necessary Right or left phrenic nerve injury is rare, and may be accidental or deliberate Deliberate division to paralyse the hemidiaphragm for volume reduction is not recommended Bollen reported left recurrent nerve injury after mediastinal lymph node dissection
Pulmonary transplantation
- Hardy and colleagues reported the first human lung transplant in 1963 Several centres have since advanced single and double sequential lung transplantation Meyers and Patterson (1999) cited one year survival over 75% They reported excellent functional results across a range of diagnoses Faughnan cautions against transplantation for diffuse pulmonary arteriovenous malformations Grover's article is recommended for further reading
- McFadden and Emory: infection is the major cause of morbidity and mortality Bronchiolitis obliterans is the second most common complication Rejection, bacterial infection and cytomegalovirus infection all produce lung dysfunction Garfein compared telescoped and end-to-end bronchial anastomosis Telescoped anastomosis had more anastomotic complications and more postoperative pneumonia
- The airway separates from the foregut in week 4; segments are complete by the end of week 5 Viability depends on capillary apposition and surfactant, not on airway number 95% of alveoli form after birth: 20 million at birth, about 300 million in the adult The azygos lobe is not a true accessory lobe but apical segment cut off by an aberrant vein Tracheal bronchus occurs in about 1 in 250 bronchoscopies and complicates one-lung ventilation Bronchial artery number and origin are variable: assume nothing until demonstrated
- Trachea runs C6 to T4 supine, 10-13 cm, at 1.5-2 cm depth at the cricoid and 7 cm at the carina Central venous catheter tips belong in the SVC above the level of the carina Segmental artery and bronchus are central; the vein is intersegmental and marks the plane Right hilum from in front: superior pulmonary vein is most superficial; through the fissure, the artery The right superior pulmonary vein drains the middle lobe as well as the upper lobe Left main bronchus in the subaortic tunnel is narrow and confined, so it obstructs more readily
- The chapter cites its sources as numbered superscripts in the text The numbered reference list itself was not carried through in this extract The slides that follow name the authors exactly as the chapter attributes them Consult the printed chapter's reference list for full bibliographic detail
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- Skandalakis' Surgical Anatomy: The Embryologic and Anatomic Basis of Modern Surgery
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