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Respiratory SystemLABMP593January 26, 2016Mahra Nourbakhsh, MD, PhD

Anatomy of Respiratory SystemRespiratory system is composed of:Thoracic walls: Bones (ribs, sternum and thoracic vertebra), Nerves, VesselsExtraparenchymal airways: Larynx, TracheaPleura: Visceral and ParietalLungs: Left and Right lungs, Airways (Intraparenchymal), Vascular tissue and Interstitial tissue

Thoracic Wall: Ribcage

Body ofsternumXiphoidprocessCostal cartilages(hyaline cartilage)Manubriumsterni12 RibsAttachment: Posteriorly: to transverse process of 12 thoracic vertebrae

Anteriorly: directly or indirectly to sternum.

Major Muscles of RespirationDiaphragm, Intercostal musclesAccessory Muscles of Respiration:SCM, Scalen, abdominal wall muscles, serratus ,etc.

Thoracic Wall: Respiratory Muscles

Extraparenchymal Airway: TracheaTrachea: Length: 10-16 cm Diameter: 25mmFormed by: C-shape cartilage and trachealis muscles.Divide to left & right main (primary) bronchus at carina to left & right lung.Lobar (Secondary) bronchus: to superior/inferior lobes on the left lung and superior/middle/inferior lobes on the right lungsegmental (tertiary) bronchus

Pleura: Visceral/ParietalVisceral Pleura: attached to the surface of the lung and continues inside the fissures.Parietal pleura: attached to the chest wall (coastal pleura), diaphragm (diaphragmatic pleura) and mediastinum (mediastinal pleura).

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Pleural Cavity:

Slit like potential space that separates visceral from parietal pleura. Contains very scant amount of fluid. Has negative pressure in comparison to air pressure, opens the lung. If the negative pressure is disturbed, the lung will collapse

Pleural Reflections:

At the lung base parietal pleura is two intercostal space lower than visceral pleura.Costophrenic (Costodiaphragmatic) recess, the first place you see the fluid in upright CXRay.

Pleura: Pleural Cavity & ReflectionsQ1: What is pleural effusion? What is empyema? Where do they accumulate

Clinical Aspects of Pleural CavityPenetration of air or blood inside the pleural cavity disturbs the negative pressure of pleural cavity, potentially life threatening. Collapsed lung, reduction of blood return to the right heart and consequently hypotension.

Air in pleural space

blood in pleural spaceWhat is the diagnosis in these two cases, both resulting from trauma?

Lungs: Left & RightLeft lung: one fissure (oblique), two lobes (upper and lower) and two lobar bronchus (upper and lower) and arteriesRight lung: two fissure (oblique and horizontal) and three lobes (upper, middle, lower) and three lobar bronchus and arteries.Each lobe: has segments and segmental bronchus and arteries.

Blood SupplyPulmonary circulation: gas exchange with outside airBronchial (systemic) circulation: supply the lung parenchyma.InnervationNo pain receptors in parenchyma. Pain receptors can be found in parietal pleura and vasculature of the lung

Quiz #1Explain why early lung parenchymal tumors are painless? When do you think lung tumors can cause pain?When does pneumonia can cause chest pain?Explain why pulmonary emboli and pulmonary hypertension are associated with chest pain?What is pleuretic chest pain? How do you differentiate pleuretic chest pain from other type of chest pain?

Clinical approach to the lung disease History symptomsPhysical exam signsDifferential diagnosis: Assessment and plan:

Symptom: DyspneaDefinition: Unpleasant subjective sensation of breathing.DDX: Apart from pulmonary causes, cardiac, psychiatric, hematologic and neuromuscular causes disease can cause dyspnea.Pulmonary causes: almost any type of pulmonary disease can cause dyspnea.

Symptom: pleuretic chest painDefinition: sharp chest pain associated with respiration and is aggravated by deep inspiration.

DDX of pleuretic chest pain: any disease that primarily (pleuritis, rib fracture) or secondarily (lung tumors, pneumonia, affects parietal pleura and/or chest wall.

Symptom: CoughProductive vs. dry coughDDX: Airway irritants: fume, GERD, nasal discharge Airway disease:Parenchymal disease:CHFDrug induced

Symptom: HemoptysisDefinition: expectoration of blood from respiratory system arises from alveoli to glottis.Massive henoptysis: >600 ml/24h, life threateningDDX:EpistaxisAirway disease: Chronic bronchitisParenchymal disease: PneumoniaVascular disease: PEMiscellaneous: TB, Tumor

Physical Exam: Breath SoundsWheezing: Low pitch continuous musical sounds Rales/Crackles: Short explosive sounds

Click and hear example of abnormal breath sounds

Anatomic Diagnostic Tests: CXR

Standard (upright): Posterior-Anterior (PA) and Lateral (Lat).Supine: Anterior-Posterior (AP) for bed-ridden patients.Lateral Decubitus: Left& Right, for pleural effusion.

Anatomic Diagnostic Tests: CXR

PA vs AP film: Note the difference in size of the heartPA vs Lat decubtous: Note fluid is moving with gravity

Anatomic Diagnostic Tests: Computed Tomography (CT) ScanX ray-based techniqueX-ray source and detector rotate around the body provide 3D pictures. Very sensitive technique for detecting small size tumor or looking to interstitial diseasesSensitivity can be increased by using contrast.

Anatomic Diagnostic Tests: Computed Tomography (CT) Scan

CT scan can detect the mass that are not visible on CXR

CT scan detects PEHigh Resolution CT (HRCT) scan is the preferred radiologic method for interstitial lung disease, in this case idiopathic pulmonary fibrosis

No Xray, no radiotracer, therefore safer technique specifically in pregnant womenVery high resolution.Application of MRI is limited in intrinsic lung disease due to signal loss by physiologic movement of chest during respiration.Excellent imaging modalities for chest wall/diaphragmatic tumorsAnatomic Diagnostic Tests: Magnetic Resonance Imaging (MRI)

Functional imaging technique, using radiotracer which emits gamma ray.A tracer is typically a biologically active derivatives of glucose called fluorodeoxyglucose (FDG) that is absorbed by metabolically active tissue (in this case neoplasm).The imaging is done by help of CT Scanner (PET-CT), therefore not only is an anatomic imaging but also is a functional imaging. Anatomic/Functional Diagnostic Tests: Positron Emission Tomography (PET) Scan

FDG avid mass high possibility of neoplasm

Biochemical Diagnostic Tests: Arterial Blood GasMajority of pulmonary diseases are associated with alteration in arterial oxygen pressure (PaO2), CO2 (PaCO2) and consequently acid-base status.ABG provides information regarding oxygenation and acid-base status rapidly.Four important components of ABG are pH, HCO3, PaO2 and PaCO2.

Medical Techniques for Obtaining Biological SpecimensCollection of sputum Percutaneous Transthoracic Needle Aspiration: Under guide of US or CT Scan a large needle is inserted through the chest wall into the lesion to obtain specimen for histology or microbiologyThoracentesis: Blind or under US guide a needle is inserted into the pleural cavity to collect fluid. The specimen is sent for microbiology, cytology and biochemical assays. It is also therapeutic

Invasive Diagnostic Modalities:BronchoscopyEndoscopic technique to visualize inside the airways

RigidFlexible

Transbronchial biopsy: Can be performed using biopsy forceps passing through the bronchoscopeBrushing: another way for obtaining small size biopsyBronchoalvelar lavage (BAL): With the bronchoscope wedged into a sub-segmental airway, aliquots of sterile saline can be instilled through the scope allowing sampling of cells and organisms from alveolar spaces.Endobronchial ultrasound and transbronchial needle aspiration: an ultrasound probe fitted in bronchoscope is used as a guide for needle aspiration of a mass

Invasive Diagnostic Modalities:Bronchoscopic Sampling

Medical Thoracoscopy: using rigid or semi-rigid thoracoscope visulaize the pleural cavity. Biopsy can taken from parietal pleuraVideo Assissted Thoracoscopic Surgery: Performs at OR using a thoracoscope, surgeon can take biopsy from lung or visceral pleura, reduces the need for thoracotomy.Open lung biopsy: thoracotomy

Invasive Diagnostic Modalities:Medical Thoracoscopy & Video Assisted Thoracoscopic Surgery (VATS)

Functional Diagnostic Test:Pulmonary Function Test (PFT)Using spirometer multiple maneuver including inspiration and expiration is performed and the machine measures volume of exchanged air and flow (volume/sec) of exchanged air.

Functional Diagnostic Test:Pulmonary Function Test (PFT)Total Lung Capacity (TLC): the volume in the lung at maximum inflationResidual Volume (RV): the volume of remains in the lung after maximum exhalation.Vital Capacity (FVC): the volume that is exhaled out after the deepest inhalation.Forces Expiratory Volume at 1 second (FEV1): the volume is breathed out in the first second of exhalation by force

PFT: Two PatternsObstructive: the hallmark is air entrapment in the lung, therefore the RV and TLC is increased. In addition due to obstruction less air is exhaled out there fore the FEV1 is reduced. FVC is slightly reduced, therefore FEV1/FVC is reduced significantly.

Restrictive: the hallmark is that air cannot enter to the lung due to the reduced lung elastic recoil (stiff lung) or weak inspiratory muscles, therefore the RV and TLC is reduced. FEV1 remains normal or slightly reduced but FVC is extremely reduced. Therefore FEV1/FVC is increased significantly.

PFT: Flow/Volume Loop

FVC

QUIZ #2The PFT results of three patients are as follow. What pattern of lung disease do they have?

Patient #1: RV=123%, TLC= 128%, FEV1=56% and FVC=89% of the normal values.

Patient #2: RV= 69%, TLC=72%, FEV1=95% and FVC=62% of the normal values.

Obstructive Lung Disease:Reversible Obstruction:Asthma

Irreversible Obstruction:Chronic Obstructive Pulmonary Disease: Emphysema and Chronic BronchitisBronchiectasisCystic Fibrosis

Asthma

Definition: Reversible bronchospasm due to inflammation causing airflow obstruction..Sign and symptoms: Triad of dyspnea, cough and wheezing. Can cause cyanosis and respiratory distressDiagnosis: in acute attack the diagnosis is clinical. But after stabilization, obstructive pattern on PFT which is reversed by using bronchodilators (ventolin).Chracot-Leyden Crystals: produced after eosinophil enzyme (lysophospholipase) is released.Curschmanns spirals: spiral shape mucus plugs found in sputum of asthmatic patientsTreatment: Bronchodilators (short acting and long acting), corticosteroids (inhaler and systemic), Leukotriene Receptor Antagonists and Anti IgE.

COPD: Chronic Bronchitis & EmphysemaChronic BronchitisProductive cough on most days for at least 3 consecutive months in two consecutive years.Obstruction is due to narrowing of airway lumen by excess mucus and thickened mucosal wall.

EmphysemaDilation and destruction of air spaces distal to terminal bronchiole.Decrease elastic recoil of lung parenchyma causes decreased expiratory driving pressure, airway collapse and air trapping.Two types: Centriacinal in smokers mostly upper zone and Panacinar in alpha-1 antitrypsin deficiency, lower lobes.

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COPD: Chronic Bronchitis & EmphysemaChronic Bronchitis (Blue Bloater)Chronic productive cough, purulent sputum, hemoptysis, mild dyspnea initially.Cyanosis, crackle, wheezing, frequently obese.

Emphysema (Pink Puffer)Dyspnea, tachypnea, minimal cough.Pink skin, pursed-lip breathing, hyperinflation of lung/barrel chest, decreased breath sounds, cachectic.

COPD: Chronic Bronchitis & EmphysemaChronic BronchitisMajor risk factor is smoking.Diagnosis: Clinical + PFT. Treatment: O2 (increase the survival), bronchodilators, corticosteroids

EmphysemaMajor risk factor is smoking. Also alpha-1 antitrypsin deficiency can cause emphysemaDiagnosis: Clinical, PFT + CXR.Treatment: O2 (increase the survival), bronchodilators, corticosteroids

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EmphysemaMarkedly dilation of airway is the hallmark of the emphysema. Bullae are markedly enlarged air space (> 1cm in diameter) which is believed to arise from ball-valve mechanism resulting more air entrapment. They can be seen in CXRay

BronchiectasisDefinition: Irreversible dilation of airway due to inflammatory destruction of airway wall resulting from persistently infected mucusRisk Factors: Post infection: Post obstruction:Impaired defenses: Sign and Symptoms: chronic cough, purulent sputum, hemoptysis, recurrent pneumonia, local crackle and wheezing

BronchiectasisDiagnosis: PFT+ HRCTTreatment: Vaccination, antibiotics, corticosteroids, chest physio and pulmonary resection.

Cystic Fibrosis (CF)Genetic disease due to mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR). The most common mutation is deletion of 3 nucleotide results in deletion of phenylalanine at position 508.Pathophysiology: Chloride transport dysfunction: thick secretion from exocrine glands (lung, pancreas, skin, reproductive organs) and blockage of secretory ducts. Lung: clogging of the airway by thick mucus build-up and obstruction later recurrent infection, bronchiectasis. The most common cause of death is secondary to respiratory failure.Pancreas: pancreatic deficiencyOther manifestation: Diabetes, azoospermia, sinusitis, meconium ileus in infants.

Cystic Fibrosis (CF)Diagnosis: Sweat chloride test, PFT, Genetic counseling.Treatment: there is no cure. Treatment is supportive by using chest physiotherapy, bronchodilators, mucolytics, inhaled tobramycin, antibiotics, pancreatic enzyme supplement.Lung transplantation: disease progresses in the transplanted lung

QUIZ #3Is asthma always an allergic response?

Name four pulmonary obstructive diseases.

What is the only treatment with mortality benefits in chronic bronchitis and emphysema?

Restrictive Lung Disease:Interstitial Lung Disease (ILD)Inflammation and/or fibrosing process in the alveolar walls results in thickening and fibrosis of the interstitial tissue

Sign and Symptoms: Dyspnea on exertion, dry crackles, non-productive cough, cyanosis, clubbing

Diagnosis: Radiology (HRCT), PFT, Bronchoscopy, BAL, Biopsy

Pathophysiology of ILD:Decrease lung complianceReduced RV, TLC and FVCImpaired diffusion of gasHypoxia and consequently on lung term right ventricular failure (Cor-pulmonale)

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Interstitial Lung Disease (ILD): EtiologyKnown: Systemic Rheumatic Disorders: RA, Scleroderma, SLE, etc.DrugsPulmonary vasculitis: Wegners granulomatosis, churg-strauss, etc.Environment/OccupationAlveolar filling disorders: Goodpasture, diffuse alveolar hemorrhage, .pulmonary alveolar proteinosisUnknown: Idiopathic pulmonary fibrosis (IPF), Sarcoidosis, Langerhans-cell histocytosis, lymphangiolyomyomatosis, pulmonary infiltrates with eosinophilia, non-specific interstitial pneumonia, lymphocytic interstitial pneumonia and cryptogenic organizing pneumonia.Do not memorize the followings

ILD: Environment/OccupationPneumoconiosesHypersensitivity pneumonitis: also known as extrinsic allergic alveolitis secondary to intense and repetative sensitization and exposure to an organic agents. Example: Farmers lung, bird breeders lung, etc.

Pneumoconioses:AsbestosisSilicosisCoal worker pneumoconiosis.

AsbestosisExposure to several forms of mineral silicate called asbestos that was used as a thermal insulator.The asbestos fibers are inhaled and induces lung fibrosis.Lots of people are not fully aware that they have been exposed. Even bystander exposure can cause asbestosis.Pleural plaques specifically at lower lobes and diaphragmatic surface can be seen on CXR.PFT reveals restrictive pattern.Most common cancer Bronchogenic carcinoma, minimum latency of 15-19 years, increased risk if also smokingMesothelioma of pleura or peritoneal are associated with exposure. 80% of mesothelioma is related to mesothelioma therefore can be compensable. Relatively shortterm exposure (