ANATOMY OF AIRWAY

ANATOMY OF AIRWAY & ITS ANAESTHETIC IMPORTANCE

MODERATOR- DR SHIVSHANKAR M

PRESENTED BY DR SHABBIR

1

FUNCTION OF NOSE The only externally visible part of the respiratory system that functions by:Providing an airway for respirationMoistening (humidifying) and warming the entering airFiltering inspired air and cleaning it of foreign matterServing as a resonating chamber for speechHousing the olfactory receptors

NOSEThe nose is divided into two regionsThe external nose, including the root, bridge, dorsum nasi, and apex The internal nasal cavityPhiltrum a shallow vertical groove inferior to the apexThe external nares (nostrils) are bounded laterally by the alae

NASAL CAVITYLies in and posterior to the external noseIs divided by a midline nasal septumOpens posteriorly into the nasal pharynx via internal naresThe ethmoid and sphenoid bones form the roofThe floor is formed by the hard and soft palates

Inspired air is: Humidified by the high water content in the nasal cavityWarmed by rich plexuses of capillariesCiliated mucosal cells remove contaminated mucus Superior, medial, and inferior conchae:Protrude medially from the lateral walls , Increase mucosal area and Enhance air turbulence and help filter airSensitive mucosa triggers sneezing when stimulated by irritating particles

During inhalation the conchae and nasal mucosa:Filter, heat, and moisten airDuring exhalation these structures:Reclaim heat and moistureMinimize heat and moisture loss

Sinuses in bones that surround the nasal cavity

Sinuses lighten the skull and help to warm and moisten the air

NOSERigid structure composed of cartilage and boneSeptal cartilage divides nasal cavity into two nasal fossaePalate divides nasal cavity and oral cavityNose divided into 3 regions

Vestibular area contains sebaceous glands; secrete sebumKeeps vibrissae soft and filter gases

Olfactory region: pseudostratified columnar epithelium and olfactory cells

Respiratoryhighly vascular; ciliated, pseudostratified columnar epitheliumContains turbinates or conchae; increase surface area (166 cm2) for humidification, heating/cooling and filtering of airMucous membranes provide up to 650-1000 ml of water/day to humidify air

Goblet cells in mucus membrane secrete 100 ml/day of mucous; aids in trapping inspired particles and prevents them from entering lower respiratory traceEach columnar cell contains 200-250 cilia; beat in waves toward oropharynx (mouth), 2cm/min

NOSEDeflection of nasal septum diminish lumen of respiratory airway-prevent passage of smallest ET Tube-test Patency of each nostril-side were obstruction is greatest anteriorly easiest to intubateWarming and humidifying inspired airIntubation is followed by mild tracheitis humidification of fresh gas flow can prevent it

NOSEResistance to airflow through nasal passages is twice the resistance through mouthRespiration , olfaction , phonation , humidification and filtrationTwo nasal fossae extend 10-14 cm from nostrils to nasopharynxNasal seputm is composed mainly by perpendicular plate of ethmoid descending from cribriform plate , septal cartilage and vomer

NOSEDisruption of cribriform plate secondary to facial trauma or head injury may allow direct communication with anterior cranial fossa , thus use of positive pressure mask ventillation can led to spread of infection causing meningitis or sepsis . nasal airways , nasotracheal tubes and nasogastric tubes may inadvertently be introduced into subarachnoid space

NOSE

NOSEEach nasal fossa provides approx 60 cm2 surface area per side for warming and humidifying inspired airInferior turbinate limits the size of nasotracheal tube that can be passed through nose Prolonged nasal intubation can cause maxillary sinus infection as its drainage is hinderedOlfactory area is liminted in upper third of nasal fossa and respiratory area in lower third of nasal fossa

NOSE10,OOO L of ambient air passes through nasal airway per day and 1 L of moisture is added to this air Moisture is partly from transudation of fluid through mucosal epithelium and from secretions produced by glands and goblet cellsThese secretions have bactericidal activity , foreign body invasion is further reduced by stiff hairs ( vibrissae ) , ciliated epithelium and extensive lymphatic drainage Kratschmer reflex - bronchiolar constriction upon stimulation of anterior nasal septum

ANAESTHESIA & HUMIDITYPRINCIPAL-Quantity of water vapour needed to saturate air with water vapour increases with temprature At room temprature of 17 c air contains 2 volumes per cent of water when fully saturated At body temprature of 37 c air in trachea contains 6 volumes percent of water vapour , thus nose and respiratory tract not only have the task of warming inspired air but also adding large quantities of water vapour

In most anaesthetic systems temperature of gases reaching patients is approximately same as room temprature TO AND FRO SYSTEM temperature of cansiter( near patient mouth ) may rise to as high as 45 *c , no time is available for cooling , provides very efficient humidificationCIRCLE ABSORPTION SYSTEM inspired mixture consists not only fresh dry gases but some expired gases containing water vapours at room temprature NON REBREATHING VALVE SYSTEM

METHODS OF HUMIDIFICATIONDIRECT INSTALLATIONWATER-BATHMOISTURE EXCHANGERMECHANICAL NEBULISERULTRASONIC NEBULISER

PHARYNXFunnel-shaped tube of skeletal muscle that connects to the:Nasal cavity and mouth superiorlyLarynx and esophagus inferiorlyExtends from the base of the skull to the level of the sixth cervical vertebra

PHARYNXIt is divided into three regionsNasopharynxOropharynxLaryngopharynx

NOSEPHARYNX LARYNX

PHARYNX12-15 cm long , extends from base of skull to cricoid cartilage anteriorly and to inferior border of sixth cervical border posteriorlyWidest at level of hyoid bone ( 5 cm ) and narrowest at level of esophagus ( 1.5 cm ) which is the most common site of obstruction after foreign body aspiration

Eustachian tube opens into lateral wall of nasopharynx Tonsillar pillars of fauces are present in lateral wall of oropharynxWall of pharynx contains two layers of muscle , external circular and internal longitudnal , each layer is composed of three paired muscles Stylo , salpingo and palatopharyngeous form the internal layer , they elevate the pharynx and shorten larynx during deglutition

Superior , middle and inferior constrictors form external layer , advance food in coordinated fashion from oropharynx to esophagus Constrictors are innervated by pharyngeal plexus , inferior constrictor has additional innervation by recurrent and external laryngeal nerve Internal layer is innervated by glossopharyngeal nerve

Superior constrictorMucous membrane of oral pharynxMucous membrane of laryngeal pharynxMiddle constrictorInferior constrictorEsophagusMucous membrane of nasopharynx

DEFENCE AGAINST PATHOGENS Inhaled particles greater than 10 um are removed by inertial impaction upon posterior nasopharynxInhaled airstream changes direction sharply at 90 degree hence cause some loss of momentum Impacted particles are trapped by waldeyers ring

Adenoid hypertrophy may restrict size of nasotracheal tube Lingual tonsil hypertrophy which is usually asymptomatic has been reported to be cause of unanticipated difficult intubation and fatal airway obstruction Retropharngeal and peritonsillar abscess poses anaesthetic challenges

Patency of pharynx is vital to patency of airway and proper gas exchange Traditionally its has been taught that in sedated or anesthetized patient , tongue fall ( reduction in genioglossus muscle activity leds to posterior displacment of tongue ) is cause of upper airway obstruction , however lately it has been proved that obstruction occurs as result of anterio-posterior dimensional changes at level of soft palate and epiglottis and not at level of tongue

OBSTRUCTIVE SLEEP APNEANarrowest portion of pharynx posterior to soft palateSubatmospheric subairway pressure created by contraction of diaphragm against resistance of nose can led to reduction in size of pharyngeal airwayLonger axis of pharyngeal airway is transverse however in OSA patients anterior-posterior axis is predominantApplication of CPAP appears to increase the volume and cross-sectional area of oropharynx

Collapsible segments of pharynx are divided into three areas retropalatal , retroglossal and retroepiglotticPatency is dependent on contractile function of pharyngeal dilator muscles Tensor palatani retracting soft palate away from posterior pharyngeal wallGenioglossus moving tongue anteriorlyMuscles moving the hyoid bone anteriorly including geniohyoid , sternohyoid and thyrohyoid

GLOTTIC CLOSURE & LARYNGEAL SPASMStimulation of superior laryngeal nerve mainly and to lesser extent trigeminal and glossopharyngeal nerve endings in supraglottic region can induce protective closure of glottis , this short lived phenomenon is polysynaptic involuntary reflex Nerve endings are highly sensitive to touch , heat and chemical stimuli , sensitive is especially intense in posterior commissure of larynx

Tongue fall can be prevented by extending head at atlanto-occipital region ( chin lift ) and lifting jaw up and forwards ( jaw thrust ) or by placing patient in lateral positionSpasm may result from intense surgical stimulation such as dilation of cervix , anus under insufficient anaesthesia , this is powerful reason why suxamethonium should be readily available

Oral procedures that promote an increase in secretions with blood in the airways, such as adenoidectomy tonsillectomy and laryngeal surgery, are associated with a higher risk. Bronchoscopy and upper gastrointestinal endoscopy can trigger the reflex by direct stimulation Certain dye stuff instilled on the eyes to evaluate the results of nasolacrimal catheterization can trigger laryngospasm, thus intubation of those patients or expelling the dye through the contralateral nostril is recommended . Anal dilation and correction of hypospadia can trigger reflex laryngospasm. anesthesia with neuroaxis block, such as sacral epidural anesthesia, and maintenance of adequate general anesthesia are recommended in children ventilated with laryngeal or face mask

Among inhalational anesthetic agents, desflurane and isoflurane when used for induction have an unacceptable rate of laryngospasm, which is one of the motives that sevoflurane and halothane are used for inhalational anesthetic induction.Laryngospasm represents focal seizure of adductors , this state is initiated by repeated superior laryngeal nerve stimulation

NASOPHARYNXLies posterior to the nasal cavity, inferior to the sphenoid, and superior to the level of the soft palate , Strictly an air passagewayLined with pseudostratified columnar epithelium , Closes during swallowing to prevent food from entering the nasal cavity pharyngeal tonsil lies high on the posterior wall Eustachian tube and auditory tube open into lateral surfaces, connect nasopharynx to middle ear, equalizes pressure of middle ear

NASOPHARYNX

OROPHARYNXExtends inferiorly from the level of the soft palate to the epiglottisOpens to the oral cavity via an archway called the fauces Serves as a common passageway for food and airThe epithelial lining is protective stratified squamous epitheliumPalatine tonsils lie in the lateral walls of the faucesLingual tonsil covers the base of the tongue

Roof of the mouth is formed by the hard and soft palateHard Bony portionSoft Fleshy portionUvula is the soft fleshy structure Epithelium is stratified squamous epithelium which is non-ciliated. Palatine (faucial) tonsils are located on each side of the oral cavity

TONSILS

TONSILSWaldeyer's ring is a continuous band of lymphoid tissue that surrounds the upper pharynx. The superior portion of the ring is located in the nasopharynx and is composed of the adenoids. Laterally the palatine tonsils and anteriorly the lingual tonsils complete the ring.Tonsillar crypts extend deeply into the body of the tonsil and are surrounded by lymphoid nodules. Debris and foreign particles collect within the crypts. The epithelium of the tonsils also varies by location. While the pharyngeal tonsil is covered mainly by multiple rows of ciliated epithelium, the palatine and lingual tonsils are covered by stratified, non-keratinized squamous epithelium.

primary follicles are formed during embryonic development and differentiate into secondary follicles after birth.secondary follicles mainly contain B lymphocytes at various stages of differentiation, along with scattered T lymphocytes.Tonsillar tumors or infections may result in ear pain due to referred pain conducted by cranial nerve IX.Pharyngeal bursa impades passage of ET Tube , if force is used penetration of mucosa and create false passage sepsis and post op collection of secretions

PHARYNXPeritonsilar abscess ( Quinsy ) nasal intubation very difficult and dangerous ET Tube deflected sharply forwards or impange and rupture abscess and lead to aspirationIn unconscious patient following anaesthesia- tendency of tongue to fall backwards and obstruct laryngeal opening To prevent this extension of head , extension of neck , placing fingers behind angles of jaw and exerting forward pressure and oropharyngeal airway

LARYNXExtent- lies at C3-C6 in midline of neck , formed by cartilaginous skeleton held together by ligaments , lined by mucous membrane and moved by muscle CARTILAGE- UNPAIRED and PAIRED UNPAIRED Epiglottis , thyroid and cricoid cartilagePAIRED Arytenoid , corniculate and cuneiform

Posterior Wall ofHypopharynx(Leading toEsophagus)Base of TongueMedianGlossoepiglotticFoldSuperior Surface ofEpiglottis

Superior Surface ofEpiglottis

Posterior Wall ofHypopharynx(Leading toEsophagus)LateralGlossoepiglotticFoldsMedianGlossoepiglotticFold

Vallecula

FRAMEWORK OF LARYNXCartilages (hyaline) of the larynxShield-shaped anterosuperior thyroid cartilage with a midline laryngeal prominence (Adams apple)Signet ringshaped anteroinferior cricoid cartilageThree pairs of small arytenoid, cuneiform, and corniculate cartilagesEpiglottis elastic cartilage that covers the laryngeal inlet during swallowing

VOCAL LIGAMENTSAttach the arytenoid cartilages to the thyroid cartilageComposed of elastic fibers that form mucosal folds called true vocal cordsThe medial opening between them is the glottisThey vibrate to produce sound as air rushes up from the lungsFalse vocal cordsMucosal folds superior to the true vocal cordsHave no part in sound production

Speech intermittent release of expired air while opening and closing the glottisPitch determined by the length and tension of the vocal cords Loudness depends upon the force at which the air rushes across the vocal cordsThe pharynx resonates, amplifies, and enhances sound qualitySound is shaped into language by action of the pharynx, tongue, soft palate, and lips

Composed of 3 single cartilaginous structures:

Epiglottis-flap, swings down to meet larynx during swallowing

Thyroid-bulk of this forms larynx

Cricoid-circular, keeps head of trachea open

LARYNXLIGAMENTS- Intrinsic and extrinsicINTRINSIC- Quadrangular membrane , conus elasticus and thyroepiglottic ligamentEXTRINSIC- Thyrohyoid membrane , cricothyroid , cricotracheal membrane , medial and lateral thyrohyoid ligament SYNOVIAL JOINTS- Cricothyroid and Cricoarytenoid

LARYNXMUSCLES- Intrinsic and extrinsicIntrinsic- Abductors of vocal cords- posterior cricoarytenoidAdductors lateral cricoarytenoid , oblique arytenoid , transverse arytenoid Tensor cricothyroid Relaxor thyroarytenoid , vocalisOpening of laryngeal inlet thyroepiglotticClosure of laryngeal inlet - aryepiglottic , interarytenoidExtrinsic- strap muscles and pharyngeal muscles

CARTILAGES OF LARYNXTHYROID CARTILAGE longest laryngeal cartilage , shield like formed by embryonic fusion of two distinct quadrilateral laminae in females the sides join at approx 120 degrees and in males closer to 90 degrees , this small thyroid angle explains the greater laryngeal prominence in males , the longer vocal cords and lower pitched voice

CRICOID CARTILAGEAnatomical lower limit of larynxThicker and stronger than thyroid cartilage and represents the only complete cartilaginous ring in airway , thus cautious downward pressure on cricoid cartilage is possible without subsequent airway obstructionRandsted and colleagues noted that placment of standard ET Tube through cricoid cartilage while preventing mucosal necrosis may be difficult

CRICOTHYROIDOTOMY

Cricothyroid membrane ( trapezoid with width 27-32 mm and height 5- 12 mm ) important surgical landmark access to airway by percutaneous or surgical cricothyroidotomy In females width and height of membrane are smaller than male , anterior vasculature overlie membrane and pose risk for hemorrhagePresence of transverse cricothyroid artery traverses upper half of membrane , hence transverse incision in lower third of membrane is recommended

INFANT LARYNXSize is 1/3 rd of adult , lumen is very narrowPosition is higher than adultEpiglottis lies at C2 and during elevation , it reaches C1 , so that infant can use nasl airway for breathing while suckingLaryngeal cartilage are softer , more pliable than adultVocal cords are only 4-4.5 mm long , shorter than in childhood and adultSupraglottic and subglottic mucosa are lax

LARYNXDuring phonation vocal cords meet in midlineOn inspiration they abduct returning to midline in expiration In order to minimize risk of any trauma to vocal cords intubation and extubation should be carried out during inspiration

VOCAL CORDS PARALYSISPosterior cricoarytenoid abductor of vocal cords Lateral cricoarytenoid adducts arytenoids closing glottisTransverse arytenoid adducts arytenoidOblique arytenoid closes glottis Aryepiglottic closes glottisVocalis relaxes cords Thyroarytenoid relaxes tension cords Cricothyroid tensor of cords

The Vagus The vagus nerve has three nuclei located within the medulla: 1. The nucleus ambiguus2. The dorsal nucleus3. The nucleus of the tract of solitarius

The nucleus ambiguus is the motor nucleus of the vagus nerve. The efferent fibers of the dorsal (parasympathetic) nucleus innervate the involuntary muscles of the bronchi, esophagus, heart, stomach, small intestine, and part of the large intestine. The afferent fibers of the nucleus of the tract of solitarius carry sensory fibers from the pharynx, larynx, and esophagus

The superior laryngeal nerve branches into internal and external branches. The internal superior laryngeal nerve penetrates the thyrohyoid membrane to supply sensation to the larynx above the glottis. The external superior laryngeal nerve innervates the one muscle of the larynx not innervated by the recurrent laryngeal nerve, the cricothyroid muscle.

Adductors of the Vocal Folds

The right vagus nerve passes anterior to the subclavian artery and gives off the right recurrent laryngeal nerve. This loops around the subclavian and ascends in the tracheo-esophageal groove, before it enters the larynx just behind the cricothyroid joint. The left vagus does not give off its recurrent laryngeal nerve until it is in the thorax, where the left recurrent laryngeal nerve wraps around the aorta just posterior to the ligamentum arteriosum. It then ascends back toward the larynx in the TE groove.

The Laryngeal MusculatureThe intrinsic muscles of the larynx, all of which are innervated by the recurrent laryngeal nerve, include the:Posterior cricoarytenoid - the ONLY abductor of the vocal folds. Functions to open the glottis by rotary motion on the arytenoid cartilages. Also tenses cords during phonation.

Abductor of Larynx

Lateral cricoarytenoid - - functions to close glottis by rotating arytenoids medially. Transverse arytenoid - - only unpaired muscle of the larynx. Functions to approximate bodies of arytenoids closing posterior aspect of glottis. Oblique arytenoid - - this muscle plus action of transverse arytenoid function to close laryngeal introitus during swallowing.

Thyroarytenoid - - very broad muscle, usually divided into three parts: Thyroarytenoideus internus (vocalis) - adductor and major tensor of free edge of vocal fold.Thyroarytenoideus externus - major adductor of vocal foldThyroepiglotticus - shortens vocal ligaments

Anatomy of the Larynx - MotionAdductors of the Vocal Folds:

Wegner and Grossman TheoryIn the absence of cricoarytenoid joint fixation, an immobile vocal cord in paramedian position has total pure unilateral recurrent nerve paralysis, and an immobile vocal cord in lateral position has a combined paralysis of superior and recurrent nerves (the adductive action of cricothyroid muscle is lost)

Causes of vocal cord paralysisMalignant : This accounts for 25% of cases, one half being caused by carcinoma of lung

Causes of vocal cord paralysisSurgical/Traumatic: (20% cases)ThyroidectomyPneumonectomyCABG Penetrating neck or chest trauma.Post intubationWhiplash injuriesPosterior fossa surgery

Causes of vocal cord paralysisNeurulogical (5-10%) Wallenberg syndrome (lateral medullary stroke)SyringomyeliaEncephalitisParkinsons, PoliomyelitisMultiple SclerosisMyasthenia Gravis, Guillian-BarreDiabetes

Causes of vocal cord paralysisInflammatory:Rheumatoid arthritis ( really a "fixed" cord here)Infectious:SyphilisTuberculosisThyroiditis Viral

Causes of vocal cord paralysisIdiopathic (20-25%):Sarcoidosis, LupusPolyarteritis nodosaOrtner's syndrome (left atrial hypertrophy).

Intracranial causesHead injuryCVABulbar poliomyelitisDistinctive featuresOther neurological signs and symptoms due to combined paralysis of soft palate, pharynx and larynx

CranialFracture base of skullJuglar foramen lesions (Glomus tumours, Naspharyngeal Carcinoma)Skull base osteomyelitisDistinctive featuresOther cranial nerve palsies (IX,X,XI)Pharyngeal, superior and Recurrent Laryngeal nerve

NeckThyroidectomyThyroid TumoursPost Cricoid CarcinomaMalignant Cervical LymphnodesDistinctive featuresSuperior and Recurrent Laryngeal nerves involved

ChestBronchogenic CarcinomaCardiothoracic SurgeryAortic AneurysmMediastinal LymphadenopathyTracheal/Oesophageal surgeryDistinctive featureInvolvement of Left Recurrent Laryngeal Nerve

LEFT VAGUS PARALYSIS

VOCAL CORD POSITIONS

Unilateral Recurrent Laryngeal Nerve Injury

This law explains median or paramedian position of the vocal cordsIt states that In all progressive lesions of RLN, abductor fibres of the nerve, which are phylogenetically newer, are more susceptible and thus first to be paralysed compared to adductor fibres RLN PARALYSIS -SEMONS LAW

RECURRENT LARYNGEAL NERVE PARALYSISUNILATERAL Unilateral injury to recurrent laryngeal nerve results in ipsilateral paralysis of all the intrinsic muscles of larynx ecxept the cricothyroid.

The vocal cords thus assumes a median or paramedian position & doesnt move laterally on deep inspiration.

Clinical features :

AsymptomaticChange in voice

The voice in unilateral paralysis gradually improves due to compensation by healthy cord which crosses midline to meet paralysed one.

Treatment : Generally no treatment is required.

(B) BILATERAL (B/L Abductor paralysis) :

Position of vocal cords : All the intrinsic muscles of larynx are paralysed, vocal cords lie in median or paramedian position due to unopposed action of cricothyroid muscles.

Clinical features : - Dyspnoea - Stridor

Movement of Vocal cord during inspiration & expiration

UNILATERAL PARALYSIS OF SLNParalysis of cricothyroid muscle & ipsilateral anaesthesia of the larynx above the vocal cord. Causes : - Thyroid surgery - Thyroid Tumors - Diptheria. Clinical features : - Weak voice with decreased pitch - Anaesthesia of the larynx on one side - Occassional aspiration. Laryngeal findings include : Askew position of glottis - Ant. Comissure is rotated to healthy side.Shortening of V.C. with loss of tension & V.C. appears wavyFlapping of the paralysed vocal cord V.C. sags down during inspiration & bulges up during expiration.

BILATERAL PARALYSIS OF SLNAn uncommon condition. Both the cricothyriod muscles are paralysed along with anaesthesia of upper larynx. Causes: - Surgical or accidental trauma - Diptheria - Cervical lymphadenopathy - Neoplastic disease Clinical features: - Both V.C. paralysis - Anaesthesia of larynx - Cough - Chocking fits - Weak & husky voice Treatment: - Tracheostomy with a cuffed tube & an oesophageal feeeding tube. - Epiglottopexy is an operation to close the laryngeal inlet to protect the lungs from repeated aspiration. It is a reversible precedure.

COMBINED/COMPLETE VOCAL CORD PARALYSIS(Recurrent & Superior Laryngeal Nerve Paralysis)

UNILATERAL

Paralysis of all the muscles of the larynx on one side except interarytenoid which also receives innervation from opposite side.

Aetiology :Thyroid surgeryLesions of nucleus ambigus which may lie medulla, post. cranial fossa, jugular foramen or parapharyngeal space.

Clinical features :All the muscles of larynx on one side are paralysedV.C. lie in cadeveric position ie. 3.5mm from the midlineGlottic incompetence results in hoarseness of voice & aspiration of liquids:

Treatment:

1. Speech therapy

2. Procedures to medialise the cord- Aim is to bring the paralysed vocal cord towards the midline so that healthy cord can meet it. This is achieved by :

Injection of teflon paste

Muscle or cartilage implant

Arthrodesis of cricoarytenoid joint

Thyroplasty type I

(B) Bilateral:

Both recurrent & superior laryngeal nerves on both sides are paralysed.Rare condition.Both cords lie in cadaveric position.Total anaesthesia of the larynx.

Clinical features :

-Aphonia: As V.C. cords doesnt meet at all.

-Aspiration: due to incompetent glottis & laryngeal anaesthesia.

-Inability to cough: due to inability of V.C. to meet which results in retention of secretions in the chest.

-Bronchopneumonia- due to repeated aspirations & retention of secretions.

Evaluation Physical ExaminationComplete Head and Neck ExaminationFlexible Fiberoptic Laryngoscopy90 degree Hopkins Rod-lens TelescopeAdequacy of Airway, Gross AspirationAssess Position of CordsMedian, Paramedian, LateralPosterior Glottic Gap on Phonation

Evaluation Unilateral ParalysisManual Compression Test

manual compression of the thyroid and cricoid cartilages modifies the position, shape, and tension of the vocal folds, adjunctive examinations used as a means of preoperative assessment of patients for medialization laryngoplasty,If quality of speech improves with pressure, patient will benefit from procedure Limitations: older patients, scarred vocal cords

Treatment:

Tracheostomy

Epiglottopexy

Vocal cord plication

Total laryngectomy

History

Symptoms:

Change in voiceHoarseness Aphonia Vocal fatigueNeck painAspirationCough

Past Medical & Surgical History :

Social History :

General ExaminationLocal Examination :

Examination of larynx & laryngopharynx IDL, FOL

Neck examination

Cranial nerve examination

Investigations : Nasopharyngolaryngoscopy

Videostroboscopy

Chest X-ray PA view

C.T. with contrast- may evaluate the entire course of recurrent laryngeal nerve

MRI

Regulation of air flowtrachea & bronchi held open by cartilaginous ringssmooth muscle in walls of bronchioles & alveolar ductssympathetic NS & epinephrine relaxation ( receptors) air flowleukotrienes (inflammation & allergens leukotrienes mucus & constriction)Protectionmucus escalator (goblet cells in bronchioles & ciliated epithelium)inhibited by cigarette smokeWarming & humidifying inspired airexpired air is 37 & 100% humidity (loss of ~400 ml pure water/day)Phonationlarynx & vocal cords

TRACHEAIt is a tube made up of cartilage and enclosed posteriorly by tracheal muscle and lined interiorly by ciliated columnar epithelium . It is about 18mm in diameter and 10-11 cm in length in adult Extent-lower part if larynx ( C6 ) to T5 , where it divides into left and right bronchiTRACHEOBRONCHIAL TREE- tracheal bifurcation occurs approx at a distance of 25 cm from upper incisor teeth in adults . Carina is a sharp shining ridge formed after bifurcation of trachea into 2 principal bronchus

Trachea moves with respirationOn deep inspiration carina can descend as much as 2.5 cm Extension of head and neck ideal position to maintain airway in anaesthetised patient can increase length of trachea by 20-30 %

RIGHT BRONCHIAL TREERight main bronchus is wider and shorter than left , being only 2.5 cm long As it is more nearly vertical than left main bronchus there is much greater tendency for either endotracheal tube or suction catheters to enter lumenIn small children under age of 3 years angulation of two main bronchi at carina is equal on both sides

In an event of ET Tube being inserted too far further complication is that bevelled end of tube ( as usually cut ) may become blocked off by its lying against mucosa of medial wall of main bronchusShort length of this bronchus makes the lumen difficult to occlude when this is required in thoracic anaesthesia Patency of middle lobe bronchus is particularly vulnerable to glandular swelling because it is closely related to right tracheobronchial group of glands

Posterior segment of upper lobe , together with apical segment of lower lobe is one of the commonest site for development of lung abscessWhen patient is lying wholly or partly on his side , inhaled material tends to gravitate into lateral portion of posyerior segment of upper lobe particularly right side If patient lies on his back- apical segment of lower lobe Incidence of lung abscess is twice as high in upper lobes as in lower lobes

LEFT BRONCHIAL TREEIt is narrower than right and is nearly 5 cm longPresence of 5 cm of bronchial lumen uninturrupted by any branching makes left main bronchus particularly suitable for intubation and blocking during thoracic aneasthesia It terminates at origin of upper lobe bronchus thus becoming main stem to lower lobe

LUNGSLight, soft, spongyConical in shape, apex, base, costal surface, medial surface, hilus. Note various impressionsRight lungThree lobes; superior, middle and inferiorOblique and horizontal fissureLeft LungTwo lobes; superior and inferior also Lingula and Cardiac notch, oblique fissure

BRONCHOPULMONARY SEGMENTS

BRONCHOPULMONARY SEGMENTS

BRONCHIOLES

AIRWAYPrimary BrochiOne to each lung continuation of tracheaRight bronchus is wider and shorter 2.5 cm as opposed to 5 cm and branches from the trachea at a greater angleSecondary bronchi one to each lobe, three in right, two in leftTertiary one to each bronchopulmonary segment approximately 10 per lungAll of the above are hyaline cartilage with no ability to change diameter

BRONCHIOLESGas ExchangePulmonary arteries carry deoxygenated blood to aleoliGas exchange occurs via diffusion through the capillary bedsReturned to heart via pulmonary veins

INNERVATIONPleura via intercostal (thoracic) nervesTracheobronchial treeParasympathetic via CN X efferent function = broncho-constriction via smooth mm., also to epithelial cells in trachea; afferent = responsible for cough reflexSympathetic from T1-T5 efferent = brocho-dilation

BLOOD SUPPLYLungs do not receive any vascular supply from the pulmonary vessels (pulmonary aa. or veins)Blood delivered to lung tissue via the bronchiole arteriesVessels evolve from aortic archTravel along the bronchial tree

Carina acts a anchor for double lumen tube Right principal bronchus is wider shorter and more vertical than left bronchusThere is much greater tendency for foreign bodies , ET Tube and suction to enter right principal bronchus

Each principal bronchus enters lung through hilum and divides into secondary ( lobar ) bronchi , one for each lobe of lungs ( 3 on right and 2 on left ) each lobar bronchi divide into tertiary( segmental bronchi) , one for each bronchopulmonary segment Tertiary ( segmental ) bronchi divides repeatedly to form very small branches called terminal bronchioles and still smaller branches called respiratory bronchioles

From proximal part of terminal bronchioles gas exchange begins and extends throughout succeding generations of airways to alveoli. corresponds to anatomical dead space and alveolar dead space respectively.Each respiratory bronchiole aeriates small part of lung known as pulmonary unit or terminal respiratory unit / acinusRespiarotry bronchiole ends in microscopic passages : alveolar ducts containing 2 or more pulmonary alveoli , atria and air saccules

ALVEOLAR STRUCTUREType I epithelial cellsthin, flat; gas exchangeType II epithelial cellssecrete pulmonary surfactant pulmonary compliance Pulmonary capillariescompletely surround each alveolus; sheet of bloodInterstitial space diffusion distance for O2 & CO2 is less than diameter of red blood cellElastic fiberssecreted by fibroblasts into pulmonary interstitial spacetend to collapse lung

Nervous or neural mechanismChemical mechanism

Nervous Mechanism: It involves respiratory centers, afferent and efferent nerves Respiratory centers: The centres in the medulla oblongata and pons that collects sensory information about the level of oxygen and carbon dioxide in the blood and determines the signals to be sent to the respiratory muscles.

Stimulation of these respiratory muscles provide respiratory movements which leads to alveolar ventilation. Respiratory centers are situated in the reticular formation of the brainstem and depending upon the situation in brainstem, the respiratory centers are classified into two groups:Medullary centersPontine centers

Medullary Centers:Inspiratory centerExpiratory center

Pontine Centers:Pneumotaxic centerApneustic center

EXPERT OPINION !!!!!!!!!