ANATOMY OF TRACHEOBRONCHIALTREE AND ITS IMPORTANCE FORANAESTHESIOLOGIST By::Dr. HUNNY NARULA Moderator::Dr. Kanchan Chauhan
TRACHEA The tracheobronchial tree and the lung parenchyma comprise the lower respiratory tract. Trachea is a midline structure that extends from lower end of cricoid cartilage at level of C6 vertebra to its termination at bronchial bifurcation. In preserved dissected room cadever : At level of T4 vertebrae Living subject in erect position : Extends to level of upper border of 5th thoracic vertebrae or in full inspiration upto 6th thoracic vertebrae. Comprises 16-20 C shaped cartilage rings, cartilages are joined vertically by fibroelastic tissue and closed posteriorly by non striated trachealis muscle
Adult Length 10-12cm. Diameter 15-20mm. Children : Trachea is smaller, deeply placed and more mobile. 1 st post natal year – Diameter doesn’t exceed 4 mm During later child hood : Diameter in mm is approx. equal to age in years.
Formation of lung bud takes place When embryo is approx. 4 wk old & it (Respiratory diverticulum, lung bud) appears as an outgrowth from ventral wall of foregut Initially lung bud communicates with foregut. When diverticulum expands caudally, 2 longitudinal ridges (k/a tracheoesophageal ridges) separate it from foregut. These ridges subsequently fuse to form Tracheoseophageal septum. Foregut is divided into dorsal portion to form oesophagus and ventral portion to form trachea and lung buds. During its separation from foregut, lung bud form the trachea and 2 lateral outpocketings, the bronchial buds.
At beginning of 5th wk, each of these buds enlarge to formContd.. And Rt. Lt. main bronchi. Rt. then form 3 secondary bronchi and Lt. two, for 3 lobes of Rt. And 2 for Lt. respectively. Epithelium and internal lining – endodermal origin Cartilagenous, muscular and connective tissue – splanchnic mesoderm surrounding the foregut
Trachea divides into right- and left- primary main bronchi. Each further divides into lobar bronchi which in turn give rise to segmental bronchi-supply air to bronchopulmonary segments. Segmental bronchi divide dichotomously, eventually giving rise to terminal bronchioles which further terminates into respiratory bronchioles. Originating from each respiratory bronchioles are 2-11 alveolar ducts leading to the alveolar sacs which are extended as a group of alveoli. Airway becomes progressively narrower, shorter and more numerous, and Cross sectional area, enlarges. Areas of tracheobronchial tree furthest from the trachea are collectively called the "distal respiratory tree"
BRONCHOSCOPIC VIEW SHOWING CARINAAND LEFT & RIGHT BRONCHUS (MOREVERTICAL).
RIGHT MAIN BRONCHUS The right main bronchus is 2 cm long on average and has an internal diameter of 10-16 mm. This is slightly larger than the diameter of the left main bronchus. The bronchus intermedius of the right bronchial tree is actually quite short ,extending for 1.0-2.5 cm until its anterior wall extends into and becomes the middle lobe bronchus. Its posterior wall extends into and becomes the right lower lobe bronchus. Volume loss caused by pleural effusion, atelectasis, elevated right hemidiaphragm, as well as traction or torsion from a fibrotic or scarred upper lobe often cause
The RIGHT UPPER LOBE BRONCHUS divides into (3)a. The apical bronchusb. The anterior bronchusc. The posterior bronchus Distally just beyond the bronchus intermedius, another division occurs into : The MIDDLE LOBE BRONCHUS with its anterior direction, dividing into(2) a).medial and b).lateral segmental bronchus.
The RIGHT LOWER LOBE BRONCHUS(5) The right lower lobe bronchus divides immediately into a a).superior segmental bronchus(jsut across from the right middle lobebronchus), and b).medial basal segmental bronchus a bit more distally and along its medial wall. Finally dividing into three lower lobe bronchi (Three musketeers): c).Antero-basal d).Latero-basal e).Postero-basal
Right upper lobe bronchus and bronchus intermedius (sec. carinas)•The carina dividing the right upper lobe from the bronchusintermedius is called the right carina 1 or RC-1.•On the right, the carina between the right middle lobebronchus and the bronchus to the right lower lobe isnamed the right carina2 or RC-2.
Bronchus intermedius and right lowerlobe bronchus
LEFT MAIN BRONCHUS The left main bronchus is usually 4-5cm long(Rt. 2cm long).Its lumen is narrower and relatively horizontal. The usual length of the left lower lobe bronchus beyond the origin of the superior segmental bronchus is 1cm. Divides into : (2) a).upper and b).lower lobe bronchus.
The UPPER LOBE BRONCHUS divides into : a). Upper division(3) Apical Posterior Anterior b).Lingular bronchus(2) Superior div. inferior div. The LOWER LOBE BRONCHUS(4): Apical Ant.basal Post basal Lat basal Med basal
Left upper lobe bronchus:Upper division and Lingula LC-1 LC-2
ANGLE OF MAIN BRONCHI A). B). Rt Lt RIGHT LEFT 45 2 45 45 5•A). In Adults: Hence more chances of rt bronchial intubation•B). In Children (under the age of 3yrs the angulationof the two main bronchi at the carina is equal on bothsides.)
Some more.. The presence of 5cm of bronchial lumen uninterrupted by any branching makes the left main bronchus particularly suitable for intubation and blocking during thoracic surgery. The patency of the rt middle lobe bronchus is particularly vulnerable to glandular swelling because it is closely related to the right tracheobronchial groups of glands.
Relationship B/W Posture And TheFocal Incidence Of Lung Abcess Patient Lying On Side: inhaled materials collect in posterior segment of right upper lobe. Patient lying on back: inhaled materials collect in apical segment of right lower lobe. Bronchopulmonary segments are functionally and anatomically distinct from each other - which matters because a segment of diseased lung can be removed surgically without adversely affecting the rest of the lung.
TRACHEOSTOMY creation of permanent or semi permanent opening(surgical airway) in the anterior wall of trachea. Also k/a tracheotomy, laryngotomy, pharyngotomy. If a cannula is in place, an unsuturedopening heals into a patent stoma withina week. If decannulation is performed(ie, the tracheostomy cannula is removed),the hole usually closes in a similar amountof time.
Indications: In The Acute Setting, indications for tracheotomy include such conditions as severe facial trauma, head and neck cancers, large congenital tumors of the head and neck (e.g., branchial cleft cyst), and acute angioedema and inflammation of the head and neck. In the context of failed orotracheal or nasotracheal intubation, either tracheotomy orcricothyrotomy may be performed. In The Chronic Setting, indications for tracheotomy include the need for long-term mechanical ventilation and tracheal toilet (e.g. comatose patients, or extensive surgery involving the head and neck). In extreme cases, the procedure may be indicated as a treatment for severe Obstructive Sleep Apnea seen in patients intolerant of Continuous Positive Airway Pressure (CPAP) therapy.
Elective tracheostomy:Anaesthesia: GAPosition: dorsal recumbent with sand bag under the shoulder.Incision: horizontal incision 1 finger breadth above supra sternal notch parallel to it from one SCM to opp. side or vertical incision in midline extending from cricoid cartilage to suprasternal notch.Division /retraction of thyroid isthmus thus exposing 3rd & 4th tracheal rings.Opening of Trachea and insertion of tube.Emergency Tracheostomy:Within 2-4 mins with vertical incision.Cricothyrotomy/mini tracheostomy:Transverse incision over the cricothyroid membrane. Kept only for 3-5 days,to be replaced with standard tubes after patient’s stabilization..
Peadiatric tracheostomy Vertical incision in trachea b/w 2nd and 3rd ring. No excision of ant. Wall of trachea. Secure the tube with neck by two sutures.Percutaneous dilatational tracheostomy Percutaneous dilatational tracheostomy (PDT) has become a commonly performed procedure in the intensive care unit (ICU) in those patients subjected to prolonged mechanical ventilation. It has largely replaced the conventional surgical tracheostomy in critical care patients, with beneﬁts in terms of cost, ease of performance, and reduced complications. Use of guide wire and Dilators. Under the vision of Bronchoscope through endotracheal tube. Not suitable for thick neck and in emergency. Signiﬁcant complications associated with PDT, including haemorrhage, pneumothorax, and paratracheal placement, have ranged in various series from 3 to 18%
PERCUTANEOUS DILATATIONALTRACHEOSTOMYLANDMARKSDaigram showing anteriorstructures of neck
PROCEDURE: Cricoid cartilage is palpated and local anaesthetic infilterated,Solutions containing adrenaline may be used to decrease bleeding at the incision site. Horizontal incision is made at chosen insertion site of sufficient size to accept a tracheostomy tube(say about 1.5 to 2cm). At this stage it may be of benefit to perform an exploratory blunt dissection(keeping in midline) to identify the anatomical landmarks.
A 14G needle and cannula(withsyringe attached) is inserted in themidline in a caudal direction(to avoidthe likelihood of the guidewire beingpassed into pharynx.). The needle isadvanced until free withdrawal of airinto the syringe confirms the entry ofthe needle and the cannula into thetrachea.this may be facilitated byusing fluid filled syringe,allowingvisualization of withdrawn airbubbles. some secretions & mucusmay be aspirated during thisprocess,which is normal. The guide wire introducer is eased out from its sheath & the “J” tip is straigthened ,the introducer is inserted into the cannula & the guidewire is advanced into the trachea
Immediately prior to insertion, the distal end of the “single stage” dilator, “rhino horn” is immersed in water or saline to act as the lubricious coating on the dilator. The dilator is passed over the guiding catheter until it reaches the “safety stop”.The lubricated tracheostomy tube is insertedloaded on its lubricated introducer over theguiding catheter through the stoma with a slighttwisting motion.The cuff of the tube is inflatedand the tube secured using sutures &/or cottonstraps.
Types of PCT : Ciaglia technique Grigg’s technique Blue rhino / Rhino horn technique Fantony’s technique Perc twist technique Surgical Tracheostomy preferable to PCT in the following situations: Coagulation abnormality High level of ventilatory support (FiO2 >.7 & PEEP > 10 cm H2O) Unstable / Fragile cervical spine Neck injury Unfavorable neck anatomy (previous surgery, tumor etc.) Obesity
A mild tonic constriction exists in all normal human airways. Mainly maintained by the efferent vagal activity . In some individuals, intense bronchoconstriction is provoked following airway stimulation with low level of stimulus as compared to normal persons. This bronchial hyperresponsiveness is termed “Reactive Airways”. BRONCHOSPASM, the clinical feature of exacerbated underlying airway hyperreactivity, is characterized by abnormal bronchial smooth muscle contraction leading to narrowing of respiratory airways. During the perioperative period, bronchospasm usually arises during induction of anesthesia but may also be detected at any stage of the anesthetic course. The commonest disease condition that falls into this entity is bronchial asthma. Others include ::chronic bronchitis, emphysema, allergic rhinitis and upper/lower respiratory tract infections. This category of patients constitutes a problem to the anaesthetist especially when the airway has to be tempered with.
Often, precise testing is not practicable preoperatively and clinicians have to rely on history to identify factors suggesting an increased likelihood for perioperative bronchospasm. One of the most important is history of recent upper respiratory tract infection characterized by cough and fever. Respiratory symptoms like nocturnal dyspnoea, chest tightness on awakening, associated breathlessness and wheezing in response to various respiratory irritants, appear highly predictive of increased bronchial reactivity Bronchospasm encountered during the perioperative period and especially after induction/intubation may involve a)an immediate hypersensitivity reaction including IgE-mediated anaphylaxis or b).a nonallergic mechanism triggered by factors such as mechanical (i.e., intubation-induced bronchospasm) or pharmacologic-induced (via histamine-releasing drugs such as atracurium or mivacurium) bronchoconstriction in patients with uncontrolled underlying airway hyperreactivity.
Intraoperatively bronchospasm is diagnosed by ventillatory difficulties characterized by: Difficult mask ventillation. Increased peak airway pressure. Expiratory wheezing. Decreased or absent breath sounds. ETco2 demonstrated a marked prolonged expiratory upstroke of the capnogram. Low concentrations of EtCO2. Desaturation. Hypotension.
Management: The key to therapy is inhalation of sympathomimetics such as albuterol. These drugs produce more rapid and effective bronchodilation than intravenous aminophylline. The beta- adrenergic aerosols like salbutamol, when inhaled before induction of anaesthesia prevents bronchospasm. Intravenous lignocaine (1.5–2 mg/kg), hydrocortisone (4 mg/kg) or glycopyrrolate (1 mg) may also help in reversing the reflex response to bronchoconstriction. Glycopyroolate may also be administered directly through the endotracheal tube. These dugs are likely to be more effective before the stimulus. Lignocaine has been shown to prevent such bronchospasm by blockade of the airway response to irritation and direct attenuation of smooth muscle response to irritation. Its use could therefore be employed when endotracheal intubation and some drugs likely to trigger bronchospasm are indicated.
Inhalational anaesthetic agents like halothane produce bronchodilatation & if inhalation anaesthesia is indicated, it has been considered the agent of choice; but its myocardial depressant and arrhythmic effects in the presence of catecholamines may limit its use. At high MAC (>1.5), both enflurane and isoflurane prevent vagally mediated bronchospasm. These agents could hence be considered useful for inhalation anaesthesia in the asthmatics. However in 1997, Rooke et al observed clinically in humans that sevoflurane at 1.1 MAC may be more efficacious than both iso- and enflurane.
Differential diagnosis: The differential diagnosis includes: inadequate anesthesia, mucous plugging of the airway, esophageal intubation, kinked or obstructed tube/circuit, and pulmonary aspiration. Unilateral wheezing suggests endobronchial intubation or an obstructed tube by a foreign body (such as a tooth). If the clinical symptoms fail to resolve despite appropriate therapy, other etiologies such as pulmonary edema or pneumothorax should also be considered.
Seen in 1:4000 live births. M:F::25:3 10-40% are pre-term Ass. with polyhydramnios(60%) Embryology: Derived from primitive foregut 4th week of gestation tracheoesophageal diverticulum forms from the laryngotracheal groove Tracheoesophageal septum develops during 4th-5thweeks – muscular + submucosal layer of T + E formed Elongates with descent of heart and lung 7thweek reaches final length
CLINICAL PRESENTATION: Choking on 1st feed Drooling of saliva Coughing Cyanosis Aspiration pnuemonia Associated anomalies:VACTRAL anomalies in 35-65%DIAGNOSIS:Antenatal: In ultrasound polyhydramnios, distended stomachImmediately after birth: Inability to pass suction catheter into the stomach.CXR: coiled orogastric tube in the cervical pouch; air in the stomach & intestine
PREOPERATIVE PREPARATION2 OBJECTIVES:1.Minimize pulmonary complications (resulting from gastric acid reflux into pulmonary system) NPO, head up position, sump tube on low continuous suction, gastrostomy under LA2.Manage dehydration & electrolyte imbalance CONVENTIONAL TEFOPERATIVE MANAGEMENT CLOSURE ENDOSCOPIC TEF REPAIR
ANAESTHETIC MANAGEMENT:THREE APPROACHES:1. Induction with inhalational agent+ topical spray+ spontaneously breathing infant+ intubation2. Iv or inhalational induction+ muscle paralysis+ intubation3. Intubation in sedated awake neonatesASSESSMENT OF ETT POSITION:GOAL:ETT just above the carina & just below the fistula Rt. main stem intubation & withdraw ETT until breath sounds are equal bilateral.(Lt. main stem bronchial intubation is poorly tolerated d/t insufficient pulmonary reserve.)
contd: If g tube present, place the end under water seal:ETT is above fistula----(+)bubbles. Connect capnograph to g-tube: ETCO2 (+), if ETT is above the fistula Rigid bronchoscopy, not proven.Beware of gastric distension give gentle positive pressure ventillation keep gastrostomy open, if present.INTRAOPERATIVE PROBLEMS: Endobronchial intubation Intubation of fistula ETT obstruction V/Q mismatch Vagal response to tracheal manipulation
Post operative management EARLY EXTUBATION DESIRABLE Caution: disruption of surgical repair with reintubation POST OP PAIN MANAGEMENT:1. Iv narcotics2. Epidural infusion:0.1%bupivacaine+fentanyl 0.5mcg/ml @ 0.1-0.2ml/kg/hr3. Rectal analgesic + LA infilteration of incision.
BRONCHOSCOPY INDICATIONS INSTRUMENTS OF CHOICE ANAESTHESIA FOR BRONCHOSCOPY
INSTRUMENTS OF CHOICERIGID FIBEROPTIC/FLEXIBLE Forein Body Removal Mechanical problems of neck massive hemoptysis Upper lobe &peripheral lesions Vascular tumors Limited hemoptysis Small children During mech ventillation Endobronchial resections Pnuemonia for selective cultures Positioning of double lumen tubes Difficult intubation Cheking position of of ETT Bronchial blockade
Anaesthetic techniques:LOCAL ANAESTHESIA: Pretreated with drying agent LA: lidocaine & tetracaine Oropharynx: nebulization or gargle LA soaked pledgets in pyriform fossa(int. branch of sup. LN) Tracheal anaesthesia: transtracheal inj. of LA or spraying of vocal cords under direct vision of laryngoscope Alternatively sup. LN block along with glossopharyngeal N. block to depress gag reflex Blocks blunt patients reflexes: pt. must be NPO for several hours after examination Advantages: awake cooperative spontaneously breathing patient Disadv.: poor tolerance to bleeding, occasional lack of cooperation
GENERAL ANAESTHESIA:1. APNEIC OXYGENATION: Preoxygenation+ induction+ skeletal muscle paralysis+ cessation of IPPV increase in PCO2 1st minute: increase is approx. 6mmHg Subsequently @ 3mmHg/min. Oxygen insufflated at 10-15ml/min Apneic period should not extend beyond 5mins Technique is limited by build up of CO2,respiratory acidosis, cardiac dysrrhythmias2. APNOEA & INTERMITTENT VENTILLATION Oxygen & anaesthesia gases delivered to bronchoscope via anaesthesia circuit Ventilation possible only when eyepiece is in place,limits interventional period by surgeon Disadv: leak around the bronchoscope
3. SANDER’S INJECTION SYSTEM: Oxygen from high pressure source(50 psig),using controllable using pressure reducing valve & toggle switch to a 18-16G needle inside & parallel to the long axis of the bronchoscope. Pressing the toggle switch jet of oxygen entraining the room air & O2-air mixture emerges at a pressure to provide adequate ventilation & oxygenation Intraluminal tracheal pressure depends upon: driving pressure from reducing valve, the size of needle jet, & the length, int. diameter & the design of bronchoscope. Pressure varies inversely with cross sectional area of the bronchoscope so insertion of catheter or biopsy forceps into the lumen causes the intra tracheal pressure to rise.4. HFPPV5. MECH VENTILLATION
PHYSIOLOGICAL CHANGES ASSOCIATED WITHFIBEROPTIC BRONCHOSCOPY: In all patients: hypoxemia, average decline in Pao2 is 20mmHg & lasts for 1-2hrs.By 24hrs blood gases are back to normal. During or after bronchoscopy patients experience increased airway obstruction: inc FRC ,dec in PaO2, VC, Fev1& Forced inspiratory flow. all return to baseline by 24hrs.changes are secondary to activation of irritative reflexes or mucosal edema. If suction at 1atm is applied, air is removed @ 14L/min this causes dec in FiO2, PAO2, & FRC leading to dec PaO2,therefore suctioning should be kept brief. If fibroscopy is planned ETT of largest possible diameter should be used. Insertion leads to significant rise in PEEP, may cause barotrauma so if PEEP is already being used, it should be discontinued. With Nd-YAG LASERS FiO2 should be kept minimum & titrated against saturation, to reduce chances of catching endobronchial fire.
COMPLICATIONS: Trauma to teeth Hemorrhage Bronchospasm Perforation Subglottic edema In most cases, it is best to intubate the trachea with an ETT after bronchoscopy under general anaesthesia. This permits avoidance or treatment of some of these problems, particularly increased airway reactivity. It also facilitates suctioning and allows the patient more gradual recovery.
SMOKING CESSATION TIMELINE – THE HEALTH BENEFITS OVER TIME In 20 minutes, blood pressure and pulse rate decreases, and the body temperature of hands and feet increases. Carbon monoxide in cigarette smoke reduces the blood’s ability to carry oxygen. At 8 hours, the carbon monoxide level in blood decreases, With the decrease in carbon monoxide, blood oxygen level increases to normal. At 24 hours, risk of having a heart attack decreases. At 48 hours, nerve endings start to regrow and the ability to smell and taste is enhanced. Between 2 weeks and 3 months, circulation improves, walking becomes easier and coughing or wheezing is not as often. Phlegm production decreases. Within several months, there is significant improvement in lung function.
In 1 to 9 months, coughs, sinus congestion, fatigue and shortness of breath decreases as there is continuous significant improvement in lung function. Cilia, tiny hair-like structures that move mucus out of the lungs, regain normal function. In 1 year, risk of coronary heart disease and heart attack is reduced to half that of a smoker. Between 5 and 15 years after quitting, risk of having a stroke returns to that of a non-smoker. In 10 years, risk of lung cancer drops. Additionally, risk of cancer of the mouth, throat, esophagus, bladder, kidney and pancreas decrease. Even after a decade of not smoking however, risk of lung cancer remains higher than in people who have never smoked. Risk of ulcer also decreases. In 15 years, risk of coronary heart disease and heart attack in similar to that of people who have never smoked. The risk of death returns to nearly the level of a non-smoker.