AP Pulmonary Part 1 2022 Keiser University PDF

Keiser University Dr. Joseph Curione PULMONARY SYSTEM Part 1 22-1 Breathing and Respiration Respiration: exchange of gases between the atmosphere, blood, and cells 3 processes required for respiration – Ventilation (breathing) – External (pulmonary) respiration – Internal (tissue) respiration The ca...

Keiser University Dr. Joseph Curione PULMONARY SYSTEM Part 1 22-1 Breathing and Respiration Respiration: exchange of gases between the atmosphere, blood, and cells 3 processes required for respiration – Ventilation (breathing) – External (pulmonary) respiration – Internal (tissue) respiration The cardiovascular system assists the respiratory system by transporting gases Structures of the Respiratory System Structurally: respiratory system is divided into 2 parts: 1. 2. Upper respiratory system Lower respiratory system Functionally: respiratory system are divided into 2 zones: 1. 2. Conducting zone (dead space up to terminal bronchioles) Respiratory zone (gas exchange in alveoli) 22-3 The upper respiratory system consists of the nose, paranasal sinuses, pharynx, and associated structures The lower respiratory system consists of the larynx, trachea, bronchi, and lungs 22-4 Upper Respiratory Tract Nose to laryngopharynx Associated structures can affect Mallampati Score. 22-5 Mallampati Score 22-6 Lower Respiratory Tract Larynx to alveoli 22-7 Thorax Bones & cartilage protect contents – 12 pairs of ribs True ribs (1-7) directly attached to sternum via costal cartilage False ribs (8-10) indirectly attached Floating ribs (11-12) not attached to sternum Supernumerary ribs (extra) – Cervical ribs – elongation of transverse process of 7th cervical vertebra (0.5% incidence) – Lumbar ribs - elongation of transverse process of lumbar vertebrae, less common Allows flexibility for movement that is needed for ventilation to occur – Oblique orientation of ribs allows for elevation of the rib cage involved with lung expansion Sternum Manubrium = uppermost part of the sternum – Suprasternal notch (jugular) Trachea lies posterior to and in line with jugular notch Same horizontal plane as T2, signifies midpoint of trachea and ideal location for the distal tip of the endotracheal tube – Sternal angle (of Louis) = where manubrium joins the body of the sternum Bifurcation of the trachea (carina) occurs at this level (T4-T5) – Manubriosternal joint = hinge-like joint between manubrium and body of sternum Allows hinge-like forward movements of sternum during inspiration and backward movements during expiration 22-9 Upper Airway - Nose Functions – warms, cleanses, humidifies inhaled air – detects odors – resonating chamber that amplifies the voice Bony and cartilaginous supports – superior half: nasal bones medially and maxillae laterally – inferior half: lateral and alar cartilages – ala nasi: flared portion shaped by dense CT, forms lateral wall of each nostril 22-10 Nasal Cartilage Caveat: Beware of Nose rings & other jewelry (Bovie) Nasal Cavity Extends from nostrils to posterior nares Vestibule: dilated chamber inside ala nasi – stratified squamous epithelium, vibrissae (guard hairs) Nasal septum divides cavity into right and left chambers called nasal fossae 22-12 Nasal Conchae and Paranasal Sinuses Turbinates & Sinuses warm, clean and moisten air for the lungs 22-13 Nasal Cavity - Conchae and Meatuses Superior, middle and inferior nasal conchae – 3 folds of tissue on lateral wall of nasal fossa – mucous membranes supported by thin scrolllike turbinate bones Meatuses – narrow air passage beneath each conchae – narrowness and turbulence ensures air contacts mucous membranes 22-14 Paranasal Sinuses 22-15 Nasal Cavity - Mucosa Olfactory mucosa – lines roof of nasal fossa Respiratory mucosa – lines rest of nasal cavity with ciliated pseudostratified epithelium Defensive role of mucosa – mucus (from goblet cells) traps inhaled particles bacteria destroyed by lysozyme & IgA 22-16 Nasal Cavity - Cilia and Erectile Tissue Function of cilia of respiratory epithelium – sweep debris-laden mucus into pharynx to be swallowed Erectile tissue of inferior concha – venous plexus that rhythmically engorges with blood and shifts flow of air from one side of fossa to the other once or twice an hour to prevent drying Spontaneous epistaxis – most common site is inferior concha 22-17 Regions of Pharynx 22-18 Pharynx Nasopharynx (pseudostratified epithelium) – posterior to choanae, dorsal to soft palate – receives auditory tubes and contains pharyngeal tonsil – 90° downward turn traps large particles (>10µm) Oropharynx (stratified squamous epithelium) – space between soft palate and root of tongue, inferiorly down to hyoid bone, contains palatine and lingual tonsils Laryngopharynx (stratified squamous) – hyoid bone to level of cricoid cartilage 22-19 Lower Airway - Larynx Glottis – vocal cords and opening between Epiglottis – flap of tissue that guards glottis, directs food and drink to esophagus Note: Infant larynx – higher in throat, forms a continuous airway from nasal cavity that allows breathing while swallowing – by age 2, more muscular tongue forces larynx down 22-20 22-21 Larynx Glottis and Epiglottis 22-22 Larynx frontal section – PA view 22-23 Vocal Cords True vocal folds are attached anteriorly to the thyroid cartilage and posteriorly to the arytenoid cartilage. 22-24 Larynx Located in adults between C3 - C6 – C3-C5 in children (superior) Framework formed by 9 total pieces of cartilage (3 paired, 3 unpaired) – Epiglottis – Thyroid – Cricoid – Arytenoid (paired) – Corniculate (paired) – Cuneiform (paired) 22-26 Nine Cartilages of Larynx Epiglottic cartilage - most superior Thyroid cartilage – largest; forms laryngeal prominence Cricoid cartilage - connects larynx to trachea Arytenoid cartilages (2) - posterior to thyroid cartilage Corniculate cartilages (2) - attached to arytenoid cartilages like a pair of little horns Cuneiform cartilages (2) - support soft tissue between arytenoids and epiglottis 22-27 Arytenoid & Corniculate cartilages epiglottis Arytenoid cartilages Thyroid cartilage Cricoid cartilage Views of Larynx 22-29 Laryngeal Cavity Rima glottidis = opening between true vocal cords and the arytenoid cartilages Narrowest portion of the airway Glottis = true vocal cords and the rima glottidis arytenoid and corniculate cartilages 22-30 Larynx In pediatric patients, Cricoid was considered the narrowest portion of the airway newer studies suggest the glottic opening may be the narrowest in the pediatric patient 22-31 Other Pediatric Airway Differences Ω Not only is the size of the airway different, the shapes and locations of the structures also vary between the infant and the adult. 22-32 During Intubation It’s very easy in a child to insert the laryngoscope blade too deep, as in the right picture. If too deep you will not see recognizable anatomy because you are looking down the esophagus and hiding the larynx. 22-33 Extrinsic Muscles Connect larynx to hyoid bone, elevate larynx during swallowing up and forward – Suprahyoid muscles: stylohyoid, mylohyoid, diagstric – Infrahyoid muscles: omohyoid, sternothyroid, thyrohyoid, and sternohyoid 22-34 Stylohyoid m. 22-35 Mylohyoid m. 22-36 Digastric m. 22-37 m. 22-38 m. 22-39 m. 22-40 m. 22-41 Muscles of the laryngeal inlet – Aryepiglottic: narrows inlet, closes glottis – Oblique arytenoid: narrows inlet, closes glottis – Together, the aryepiglottic and oblique arterynoid act as a purse-string sphincter during swallowing – Transverse arytenoid: assists aryepiglottic & oblique arytenoids – Thyroepiglottic: widens inlet 22-42 Intrinsic Muscles Intrinsic muscles - rotate corniculate and arytenoid cartilages adducts (tightens: high pitch sound) or abducts (loosens: low pitch sound) vocal cords Muscles involved with movement of true cords: – Cricothyroids: tense vocal cords ONLY intrinsic muscle to lie outside the cartilaginous framework of the larynx – Thyroarytenoids: relax vocal folds Vocalis m.: part of the thyroarytenoids, adjusts tension of cords – Lateral cricoarytenoids: adducts cords, closes (slide 24) – Transverse arytenoids: adducts cords, closes – Oblique arytenoids: adducts cords, closes – Posterior cricoarytenoids: abducts vocal cords & folds, opens ONLY ABDUCTOR muscle of vocal cords (slide 24) 22-43 Intrinsic Muscles of the Larynx 22-44 Cricothyroid m. 22-45 Blood Supply to the Larynx Blood supply to the larynx is supplied via the external carotids – Superior laryngeal a. & Superior Thyroid a. & subclavian arteries – Inferior laryngeal a. & Inferior thyroid a. 22-46 Subclavian à thyrocervical trunk à Inferior thyroid a. à Inferior laryngeal a. 22-47 22-48 Larynx Innervation Innervation of the larynx (C.N. X, Vagus) – Sensory: Interior Branch of Superior laryngeal nerve provides sensation for upper portion of the larynx down to and including upper half of the vocal cords Recurrent laryngeal nerve transmits sensation below the true cords and lower half of the cords – Motor: ALL intrinsic muscles except the cricothyroid are innervated by the RECURRENT LARYNGEAL nerve – Cricothyroid muscle is innervated by superior laryngeal nerve Trachea 22-50 Trachea Fibrocartilaginous tube, approximately 10-20cm long and 12mm in diameter Begins at the end of the larynx (C6) and extends to T5-6 Supported by 16-20 C-shaped rings of cartilage with smooth muscle posteriorly The carina is the lower most portion of the trachea where it divides into primary bronchi Lined with ciliated pseudostratified epithelium which functions as mucociliary escalator 22-51 Removing Inhaled Particles The lungs produce 100mL of mucous per day Turbulent flow helps trap precipitate Cough Reflex Mucociliary escalator mechanism – Impaired by endotracheal intubation & volatile anesthetics – Ciliated epithelial cells beat particles up the airway to be swallowed in the oropharynx Cilia remove “contaminated” mucus 22-52 Branching of Tracheobronchial Tree Dead Space Gas Exchange Conducting Zone SECONDARY (LOBAR) BRONCHI – Bronchospasm occurs here – Three on the right, two on the left (related to lobes) SEGMENTAL BRONCHI – Bronchospasm occurs here, can be treated by increasing positive pressure, deepening the anesthetic, increasing the inspiratory time of ventilation, and directly spraying lidocaine into the trachea – Ten on right, eight on left TERMINAL BRONCHIOLES – Diameter of 1 mm and contain NO cartilage – Relatively thick smooth muscle wall compared to lumen Can contract during asthma attack No goblet cells Respiratory Zone 22-55 Bronchial Circulation vSupplied by systemic circulation vSome mixes with alveolar venous return, causing an anatomic shunt – area of the lung where there is perfusion but no ventilation. 22-56 22-57 Bronchial Circulation AV shunt causes slight dilution of PO2 (bronchial venous mixes w/ pulmonary vein blood). This dilution is what causes the alveolar-arterial gradient. PA – Pa ~ 5-15mmHg 22-58 Alveolar-Arterial Gradient PAO2 – PaO2 N = 5 – 15 mmHg Useful in determining the cause of restrictive lung disease (extrinsic vs. intrinsic) If Gradient is normal, blame the chest wall (extrinsic restrictive disease) If Gradient is increased, then the problem is in the lung (intrinsic restrictive lung ds.) 22-59 Bronchial Innervation v Sensory & Motor via Vagus v Parasympathetic: Ach bronchoconstriction v M3 (Gq) v Sympathetic: Epi/Norepi bronchodilation v B2 (Gs) 22-60 Respiratory Zone Composed of: – Acinus (terminal respiratory unit) Respiratory bronchioles Alveolar ducts Alveoli – Alveoli are formed from birth to age 4, they continue to maximally expand until age 8 22-61 Respiratory Zone Respiratory bronchioles = first segment of airway where gas exchange occurs (transitional zone) Alveolar ducts = walls completely lined with alveoli Alveolar sac = located at end of each 3rd generation of alveolar ducts Diffusion is the main mechanism for gas exchange from the alveoli into the blood – More lipid soluble anesthetics will diffuse easier, resulting in build up in the blood stream Diffusion = Area/Thickness In a normal lung, the area of the blood gas interface is about the size of a tennis court 22-62 Alveoli 300 million in the adult, Polygon shape maximizes surface area Surrounded by 1,000 pulmonary capillaries each Type I alveolar cells – Squamous, Form walls, involved with gas exchange Type II alveolar cells – Cuboidal Produce surfactant (­ #s limit gas exchange in ds) Alveolar macrophages = eliminate foreign debris Alveolar pores (pores of Kohn) allow for collateral ventilation 22-63 Alveolar Stability Alveoli have tendency to collapse This is primarily prevented by: – Surfactant – Alveolar pores – Interdependence 22-64 Lungs Cone shaped structures located in the thorax Occupy all of thoracic cavity except mediastinum Right lung has three lobes Left lung has two lobes Left lung is more narrow than the right The lungs are innervated by the pulmonary plexus Sympathetic fibers T2-T6 and parasympathetic fibers from the vagus Few to no pain receptors in lungs 22-65 Lungs There is a normal perfusion and ventilation (V/Q) difference between the two lungs because of different surface areas The right lung has three lobes and receives 60% of the cardiac output to the lungs Parasympathetic fibers produce constriction of the airways and increase mucus secretion by the mucus glands Sympathetic hormones produce dilation of the airways (beta-2 response) 22-66 Lungs Pleural membranes are serous membranes that line the thoracic cavity and cover the lungs – 10cc of pleural fluid produced per lung, prevents friction in Pleural Cavity. Creates pressure gradient (discussed later) – Visceral pleura attached to outer surface of the lungs, parietal pleura line the wall of the thoracic cavity 22-67 Thorax - Cross Section 22-68 Pleural Cavity Pneumothorax – air in the P.C. Hemothorax – blood in P.C. Empyema – pus in the P.C. Pleurisy/Pleuritis – inflammation/fluid in P.C. Copyright © 2014 John Wiley & Sons, Inc. All rights reserved. Pulmonary Ventilation Breathing (pulmonary ventilation) – one cycle of inspiration and expiration – quiet respiration – at rest – forced respiration – during exercise – Lung volumes are discussed in 2nd pulmonary lecture Flow of air in and out of lung requires a pressure difference between air pressure within lungs and outside body 22-70 Muscles of Respiration Diaphragm 22-71 Diaphragm Accounts for most Tidal volume Dome-shaped muscle that forms the floor of the thorax and separates the thoracic cavity and the abdominal cavity Separated into two halves = hemidiaphragms – Right hemidiaphragm is higher than the left (heart pushes left side down; liver raises right side) Major diaphragmatic foramina: – Vena cava foramen – Esophageal hiatus (esophagus and vagus nerve pass through; site of hiatal hernia) – Aortic hiatus 22-72 Diaphragm Innervation is supplied by paired phrenic nerves – C3-5 (C4 provides 70% of contribution) – Allows for half of the diaphragm to continue working if one side is damaged – Motor AND sensory nerves. Sensory diaphragmatic pain referred to the shoulder areas Major factors affecting the position of the diaphragm: – Recoil of lungs – Thoracic viscera pressure (e.g. CHF) – Abdominal viscera pressure (e. g. pregnancy) – Abdominal muscle activity (contraction pushes diaphragm upward) 22-73 Diaphragm Movement during normal breathing – 1-2cm normal tidal breathing – 7-13cm with deep breathing The diaphragm accounts for 60-75% of normal tidal volume respiration Diaphragm is a skeletal muscle (you can paralyze it!) 22-74 Intercostals External intercostal muscles oriented obliquely forward and downward – Responsible for up to 25% of tidal volume that enters lungs during normal breathing at rest – Lift up the ribs during inspiration Internal intercostal muscles oriented opposite and downward – Assist in expiration by pulling the ribcage down – Aids in forced expiration 22-75 Boyles Law 22-76 Pressure Changes in Ventilation Factors Affecting Ventilation Surface tension – Inwardly directed force in the alveoli which must be overcome to expand the lungs during each inspiration Elastic recoil – Decreases the size of the alveoli during expiration Compliance – Ease with which the lungs and thoracic wall can be expanded 22-78