Large airways consist of…
nose, pharynx, larynx, trachea and bronchi.
Small airways consist of…
bronchioles and terminal bronchioles (large numbers in parallel give the least resistance).
The conducting zone acts to…
warm, humidify and filter air but it does not participate in gas exchange. It is anatomic dead space.
Cartilage and goblet cells extend to…
the end of the bronchi.
Pseudostratified ciliated columnar cells (which beat mucus up and out of the lungs) extend to…
the beginning of the terminal bronchiles and then transitions to the cuboidal cells.
Airway smooth muscles extend to…
the end of terminal bronchioles and is sparse beyond this point.
The respiratory zone consists of…
respiratory bronchiles, alveolar ducts and alveoli. These participate in gas exchange.
The respiratory zone is mostly made of…
cuboidal cells in respiratory bronchioles and then is simple squamous cells up to the alveoli. No cilia.
Type I pneumocytes make up…
97% of the alveolar surfaces. They line the alveoli. Squamous. Thin for optimal gas diffusion.
Type II pneumocytes secrete…
pulmonary surfactant which leads to decreased alveolar surface tension and prevention of alveolar collapse (atelectasis). They are cuboidal and clustered.
Type II pneumocytes also serve as…
precursors to type I cells and other type II cells. They proliferate during lung damage.
Clara (club) cells are…
nonciliated; columnar/cuboidal with secretory granules.
Clara cells secrete…
a component of surfactant and degrade toxins.
Collapsing pressure =
2(surface tension)/radius
Alveoli have increased tendency to collapse on…
expiration as radius decreases.
Pulmonary surfactant is a complex mixture of…
lecithins, the most important of which is dipalmitoylphosphatidylcholine.
Surfactant synthesis begins around…
week 26 of gestation but mature levels are not achieved until around week 35.
Lecithin to sphingomyelin ratio that indicates fetal lung maturity is…
> 2.
Right lung has…
3 lobes. Left Lobe has Less and Lingula.
The more common site for inhaled foreign bodies is…
the right lung bc the right main stem bronchus is wider and more vertical than the left.
Aspiration while upright ends up in the…
lower portion of the right inferior lobe.
Aspiration while supine ends up in the…
superior portion of the right inferior lobe.
The relation of the pulmonary artery to the bronchus at each lung hilus is described by…
RALS - Right Anterior; Left Superior.
Structures perforating the diaphragm:
-At T8: IVC -At T10: esophagus, vagus -At T12: aorta, thoracic duct, azygous vein
The diaphragm is innervated by…
C3, 4 and 5 (phrenic nerve).
Pain from diaphragm irritation can be referred to..
the shoulder (C5) or the trapezius ridge (C3, 4).
Inspiratory Reserve Volume (IRV)
air that can still be breathed in after normal inspiration
Tidal Volume (TV)
air that moves into the lung with each quiet inspiration (about 500 mL)
Expiratory Reserve Volume (ERV)
air that can still be breathed out after normal expiration
Residual Volume (RV)
air in lung after maximal expiration; cannot be measured on spirometry
Inspiratory capacity (IC)
IRV + TV
Functional Residual Capacity (FRC)
RV + ERV (volume in lungs after normal expiration)
Vital Capacity (VC)
TV + IRV + ERV; maximum volume of gas that can be expired after a maximal inspiration
Total Lung Capacity (TLC)
IRV + TV + ERV + RV; volume of gas present in lungs after a maximal inspiration
V(D) =
physiologic dead space = anatomic dead space of conducting airways plus functional dead space in the alveli (volume of inspired air that does not participate in gas exchange)
Equation for V(D) =
VT x (PaCO - PECO)/PaCO
The largest contributor of functional dead space is…
the apex of a healthy lung.
Minute ventilation (V(E))
total volume of gas entering the lungs per minute V(E) = V(T) x RR
Alveolar ventilation (V(A))
volume of gas per unit time that reaches the alveoli V(A) = (VT-VD) x RR
The lungs have a tendency to…
collapse inward and the chest wall has a tendency to spring outward.
At FRC, the inward pull of the lung is…
balanced by outward pull of the chest wall and the system pressure is atmospheric.
Elastic properties of the chest wall and lungs determine their…
combined volume.
At FRC, airway and alveolar pressures are…
0 and intrapleural pressure is negative (which prevents pneumothorax). PVR is at minimum.
Compliance is…
the chang in lung volume for a given change in pressure.
Compliance is decreased in…
pulmonary fibrosis, pneumonia and pulmonary edema.
Compliance is increased in…
emphysema and normal aging.
Hemoglobin (Hb) is composed of…
4 polypeptide subunits (2 alpha and 2 beta) .
Hb exists in 2 forms:
- T (taut) form has a low affinity for O2 2. R (relaxed) form has a high affinity for O2
Hb exhibits..
positive cooperativity and negative allostery.
Factors that favor the taut form of Hb
-increased Cl -increased H+ -CO2 -2,3-BPG -Temperature
Factors that favor the taut form of Hb cause…
the dissociation curve to shift to the right leading to increased oxygen unloading
Fetal Hb (2 alpha and 2 gamma) has lower affinity for…
2,3-BPG and thus higher affinity for O2.
Methemoglobin is…
the oxidized form of Hb (ferric, Fe3+) that does not bind O2 as readily but has increased affinity for cyanide.
Methemoglobinemia may present with…
cyanosis and chocolate-colored blood.
To treat cyanide poisoning, use…
nitrites to oxidize Hb to methemoglobin which binds the cyanide. Then use thiosulfate to bind this cyanide forming thiocyanate which is renally excreted.
Methemoglobinemia can be treated with…
methylene blue.
Carboxyhemoglobin is a…
form of Hb bound to CO in place of O2. This causes decreased oxygen binding capacity with a left shift in the oxygen hemoglobin dissociation curve and decreased O2 unloading in tissues.
The affinity of CO for Hb is…
200x greater than O2.
The oxygen-Hb dissociation curve has a…
sigmoidal shape due to the positive cooperativity (tetrameric Hb can bind 4 O2 molecules and has higher affinity for each subsequent O2 molecule bound).
Myoglobin does not show positive cooperativity bc…
it is monomeric. Curve lacks sigmoid shape.
When the oxygen-hemoglobin curve shifts to the right, there is…
decreased affinity of Hb for O2. (facilitates unloading of O2 to tissue)
An increase in all factors of the O2-Hb curve cause…
a shift of the curve to the right.
The curve for fetal Hb is…
shifted to the left.
Factors that cause right shift (BAT ACE):
B - BPG A - Altitude T - Temperature A - Acid (H+) C - CO2 E - Exercise
Cyanosis results when…
deoxygenated Hb > 5 g/dL.
Pulmonary circulation is normally…
low-resistance, high-compliance system.
In the lungs, a decrease in PaO2 causes…
a hypoxic vasoconstriction (opposite of most tissues) that shifts blood away from poorly ventilated regions of the lung to well-ventilated regions.
Perfusion limited
-O2 (normal health) -CO2 -N2O
In perfusion limited exchange, gas will…
equilibrate early along the length of the capillary and diffusion can be increased only if blood flow increases.
In diffusion limited exchange, gas…
does not equilibrate by the time blood reaches the end of the capillary.
Diffusion limited
-O2 (emphysema, fibrosis) -CO
An increase in the A-a gradient may occur in…
hypoxemia; causes include shunting, V/Q mismatch, fibrosis
Situations with normal A-a gradient despite Hypoxemia
-high altitude -hypoventilation
Hypoxemia with increased A-a gradient (3)
-V/Q mismatch -diffusion limitation -right to left shunt
Causes of hypoxia (4)
- decreased CO 2. hypoxemia 3. anemia 4. CO poisoning
V/Q in the apex of the lung =
3 (wasted ventilation)
V/Q at the base of the lung =
.6 (wasted perfusion)
Both ventilation and perfusion are greater at…
the base of the lung than the apex.
V/Q approaches 1 with…
exercise because there is vasodilation of apical capillaries resulting in a V/Q ratio that approaches 1.
Organisms that thrive in high O2 will…
flourish in the apex (TB).
V/Q approaches zero in…
airway obstruction (shunt). 100% O2 will not improve PO2.
V/Q approaches affinity in…
blood flow obstruction. 100% O2 will improve PO2.
CO2 is transported from tissues to the lungs in 3 forms:
- HCO3- (90%) 2. Carbaminohemoglobin (HbCO2) (5%) 3. dissolved CO2 (5%)
Haldane effect
In the lungs, oxygenation of Hb promotes dissociation of H+ from Hb. This shifts equilibrium toward CO2 formation. Therefore, CO2 is released from RBCs.
Bohr effect
In peripheral tissues, increased H+ from tissue metabolism shifts the curve to the right unloading O2.
Decreased atmospheric oxygen leads to…
decreased PaO2 which increases ventilation which decreases PaCO2.
Chronic changes in response to high altitude
-decreased PaCO2 -increased ventilation -increased erythropoietin -increased 2,3-BPG -increased mitochondria -increased renal excretion of HCO3- (to compensate for respiratory alkalosis)
Increased erythropoietin leads to…
increased hematocrit and Hb
Chronic hypoxic pulmonary vasoconstriction from high altitude leads to…
RVH.
Response to exercise
-increased CO2 production -increased O2 consumption -increased ventilation rate to meet O2 demand -increased pulmonary bf due to increased CO -decreased pH (secondary to lactic acidosis)
In response to exercise, there is no change in…
PaO2 and PaCO2 but ther is increase in venous CO2 and decrease in venous O2.
Rhinosinusitis is…
obstruction of sinus drainage into the nasal cavity leading to inflammation and pain over the affected area (typically maxillary sinuses).
Most common acute cause of rhinosinusitis is…
viral URI. This may cause a superimposed bacterial infxn (S. pneumoniae, H. influenzae and M. catarrhalis).
Deep vein thrombois is predisposed by…
Virchow Triad: 1. Stasis 2. Hypercoagulability (most commonly Factor V Leiden) 3. Endothelial damage
Homan sign
doriflexion of foot leads to leg pain; seen in DVT
Prevention and acute management of DVT
heparin
Long-term prevention of DVT recurrence
warfarin
A pulmonary emboli causes a…
V/Q mismatch which leads to hypoxemia and then respiratory alkalosis.
Symptoms of Pulmonary Emboli
-sudden onset dyspnea -chest pain -tachypnea -sudden death
Types of PE
- fat 2. air 3. thrombus 4. bacteria 5. amnitotic fluid 6. tumor
Fat emboli is associated with…
long bone fractures and liposuction.
Classic Triad of PE
- Hypoxemia 2. Neuro abnormalities 3. Petechial rash
Amniotic fluid emboli can lead to…
DIC, especially post-partum.
Gas emboli are due to…
nitrogen bubbles that precipitate in ascending divers; treat with hyperbaric oxygen.
The imaging test of choice for PE is…
CT pulmonary angiography.
Lines of Zahn are…
interdigitating areas of pink (platelets, fibrin) and red (RBCs) found only in thrombi formed before death.
Obstructive lung diseases result in..
air trapping in the lungs. Airways close prematurely at high lung volumes leading to: increaesed RV, decreased FVC.
PFTs of obstructive lung disease
-markedly decreased FEV1 -decreased FVC -decreased FEV1/FVC (hallmark) -V/Q mismatch
Chronic, hypoxic pulmonary vasoconstriction can lead to…
cor pulmonale.
Types of Obstructive Lung Disease (4)
- Bronchitis (blue bloater) 2. Emphysema (pink puffer) 3. Asthma 4. Bronchiectasis
Bronchitis shows…
hyperplasia of the mucus secreting glands in the bronchi (Reid index > 50%)
Findings of bronchitis
- wheezing 2. crackles 3. cyanosis 4. late-onset dyspnea 5. CO2 retention
Chronic Bronchitis is defined as…
a productive cough for more than 3 months per year for more than 2 years.
Emphysema shows…
enlargement of airway spaces, decreased recoil, increased compliance, decreased DLCO.
Increased compliance in emphysema is due to…
loss of elastic fibers due to increased elastase activity.
Two types of Emphysema
- Centriacinar - associated with smoking 2. Panacinar - associated with alpha1-antitrypsin acitivity
Findings of Emphysema
-barrel chest -exhalation through pursed lips (to increase airway pressure and prevent airway collapse during respiration)
Asthma is…
bronchial hyperresponsiveness that causes reversible bronchoconstriction.
Asthma shows…
smooth muscle hypertrophy Curschmann spirals (shed epithelium form mucus plugs) Charcot-Leyden crystals (from breakdown of eosinophils)
Test for asthma with…
the methacholine challenge.
Findings of asthma
-cough -wheezing -tachypnea -dyspnbea -hypoxemia -decreased I/E ratio -pulsus paradoxus -mucus plugging
Bronchiectasis is…
chronic necrotizing infection of bronchi leading to permanently dilated airways, purulent sputum , recurrent infxns and hemoptysis.
Bronchiectasis is associated with…
- bronchial obstruction 2. poor ciliary motility (smoking) 3. Karatgener 4. cystic fibrosis 5. allergic bronchopulmonary aspergillosis
Restrictive lung diseases have…
decreased lung volumes decreased FVC decreased TLC
PFTs of restrictive lung disease
-FEV1/FVC ratio is > 80%
2 Types of Restrictive Lung Disease
- Poor breathing mechanics 2. interstitial lung diseases
Features of restrictive lung disease due to poor breathing mechanics
- extrapulmonary 2. peripheral hypoventilation 3. normal A-a gradient
Restrictive diseases due to poor muscular effort
-polio -myasthenia gravis
Restrictive diseases due to poor structural apparatus
-scoliosis -morbid obesity
Features of restrictive lung disease due to interstitial lung disease
-decreased pulmonary diffusing capacity -increased A-a gradient
Findings of Sarcoidosis
-bilateral hilar lymphadenopathy -noncaseating granuloma -increased ACE and Ca2+
Hypersensitivity pneumonitis is often seen in…
farmers and those exposed to birds. It is a mixed type III?IV HSR due to rxn to environmental Ag.
Pneumoconioses increase the risk of…
cor pulmonale and Caplan syndrome.
Caplan syndrome is…
RA, and pneumoconioses with intrapulmonary nodules.
Asbestosis is associated with…
shipbuilding, roofing and plumbing.
Findings of Asbestosis
-“ivory white” calcified pleural plaques -asbestos (ferruginous) bodies: golden-brown fusiform rods resembling dumbbells
Calcified pleural plaques are pathognomic of…
asbestos exposure but they are not pre-cancerous. They are associated with an increased incidence of bronchogenic carcinoma and mesothelioma.
Asbestosis affects…
the lower lobes.
Prolonged coal dust exposure seen in coal workers’ pneumoconiosis leads to…
macrophages laden with carbon leading to inflammation and fibrosis. aka black lung disease.
Coal workers’ pneumoconiosis affects…
the upper lobes.
Anthracosis is…
an asymptomatic condition found in many urban dwellers exposed to sooty air.
Silicosis is associated with…
foundaries, sandblasting, and mines.
Pathogenesis of silicosis
macrophages respond to silica and release fibrogenic factors leading to fibrosis.
Silicosis gives an increased risk of…
TB and bronchogenic carcinoma.
Silicosis affects the…
upper lobes.
Classic finding of silicosis
“eggshell” calcification of hilar lymph nodes
Neonatal respiratory distress syndrome is due to…
surfactant deficiency that leads to increased surface tension and alveolar collapse.
A lecithin: sphinogmyelin ratio of less than 1.5 in amniotic fluid is predictive of…
neonatal RDS.
Persistently low O2 tension is a risk for…
PDA.
Therapeutic supplemental O2 for RDS can result in…
retinopathy of prematurity and bronchopulmonary dysplasia.
Risk factors for neonatal RDS
- prematurity 2. maternal diabetes (due to increased fetal insulin) 3. C-section (due to decreased release of fetal gluococorticoids)
Treatment for neonatal RDS
- maternal steroids before birth 2. artificial surfactant for the infant
Acute Respiratory Distress Syndrome (ARDS) may be caused by…
trauma, sepsis, shock, gastric aspiration, uremia, acute pancreatitis or amniotic fluid embolism.
Pathogenesis of ARDS
diffuse alveolar damage leads to increased alveolar capillary permeability leadsto protein-rich leakage into alveoli and noncardiogenic pulmonary edema (normal PCWP)
ARDS results in…
formation of intra-alveolar hyaline membrane
Initial damage seen in ARDS is due to…
release of neutrophilic substances toxic to the alveolar wall, activation of coagulation cascade and oxygen-derived free radicals.
Normal pulmonary artery pressure =
10-14 mmHg
Pulmonary HTN levels
>25 mmHg at rest
Pulmonary HTN results in…
arteriosclerosis, medial hypertrophy, and intimal fibrosis of the pulmonary arteries.
Primary pulmonary HTN is due to…
an inactivating mutation in the BMPR2 gene (which normally functions to inhibit vascular smooth muscle proliferation; poor prognosis.
Secondary pulmonary HTN is due to…
COPD (destruction of lung parenchyma) mitral stenosis (increased resistance leading to increased pressure) recurrent thromboemboli (decreased cross-sectional area of pulmonary vascular bed) autoimmune disease (sclerosis) left to right shunt (endothelial injury) sleep apnea living at high altitude
Course of pulmonary HTN
severe respiratory distress leads to cyanosis and RVH leads to death from decompensated cor pulmonale
Sleep apnea is…
repeated cessation of breathing for more than ten seconds during sleep.
PaO2 during the day of people with sleep apnea is…
normal.
Nocturnal hypoxia from sleep apnea leads to…
HTN, arrhythmias and sudden death
Central sleep apnea
no respiratory effort
Obstructive sleep apnea
respiratory effort against airway obstruction; associated with obesity and loud snoring
Treatment for Sleep apnea
-weight loss -CPAP -surgery
Increased erythropoiesis is seen in sleep apnea because..
the hypoxia leads to increased EPO release.
Obesity hypoventilation syndrome
obesity leads to hypoventilation leads to decreased PaO2 and increased PaCO2 during waking hours
Pleural effusion physical findings
decreased breath sounds dull to percussion decreased fremitus
Atelectasis physical findigns
decreased breath sounds dull to percussion decreased fremitus trachea deviation toward side of lesion
Spontaneous pneumothorax physical findings
decreased breath sounds hyperresonant to percussion decreased fremitus tracheal deviation toward side of lesion
Tension pneumothorax physical findings
decreased breath sounds hyperresonant to percussion decreased fremitus tracheal deviation away from side of lesion
Consolidation physical findings
bronchial breath sounds late inspiratory crackles dull to percussion increased fremitus
On CXR, pneumothorax is…
radiolucent (dark).
Wedge-shaped opacity think…
pulmonary embolism
Presentation of lung cancer
cough hemoptysis bronchial obstruction wheezing pneumonic “coin” lesion on CXR noncalcified nodule on CT
SPHERE of complications from lung cancer
Superior vena cava syndrome Pancoast tumor Horner syndrome Endocrine (paraneoplastic) Recurrent laryngeal symptoms Effusions
All lung cancers are associated with smoking except…
bronchial carcinoid.
The most common lung cancer in nonsmokers and overall (except for mets) is…
adenocarcinoma.
Activating mutations for adenocarcinoma include…
k-ras EGFR ALK
Adenocarcinoma is associated with…
hypertrophic osteoarthropathy (clubbing).
Bronchioloalveolar subtype (adenocarcinoma in situ), on CXR shows…
hazy infiltrates to pneumonia.
Histology of Bronchioloalveolar adenocarcinoma
grows along alveolar septa leading to an apparent “thickening” of the alveolar walls
Characteristics of Squamous Cell Carcinoma of the Lung
-hilar mass arising from bronchus -cavitation -cigarettes -hypercalcemia
Squamous cell carcinoma has hypercalcemia because it…
produces PTHrP
Histology of squamous cell carcinoma
-keratin pearls -intercellular bridges
Small cell carcinoma Characteristics
-undifferentiated -amplification of myc (L-myc) -inoperable (treat with chemo)
Small cell carcinoma may produce…
ACTH, ADH or Antibodies against presynaptic Ca2+ channels (Lambert-Eaton)
Histology of Small Cell Carcinoma
-neoplasm of neuroendocrine Kulchitsky cells (small dark blue cells)
Characteristics of Large Cell Carcinoma
-highly anaplastic, undifferentiated -poor prognosis -less responsive to chemo -removed surgically
Large cell carcinoma histology
pleomorphic giant cells
Bronchial carcinoid tumor characteristics
-excellent prognosis -symptoms usually due to mass effect -occasionally carcionid syndrome
Bronchial carcinoid tumor histology
-nests of neuroendocrine cells -chromogranin A positive
Mesothelioma is…
malignancy of the pleura associated with asbestosis.
Mesothelioma results in..
hemorrhagic pleural effusions and pleural thickening.
Histology of mesothelioma shows…
psammoma bodies.
Pancoast tumor is…
carcinoma that occurs in the apex of the lung and may affect the cervical sympathetic plexus causing Horner syndrome (ipsilateral ptosis, miosis and anhidrosis), SVC syndrome, sensorimotor deficits and hoarseness.
Superior vena cava syndrome is…
an obstruction of the SVC that impairs blood drainage from the head (facial plethora), neck (JVD) and upper extremities (edema). Medical emergency.
SVC syndrome is commonly caused by…
malignancy and thrombosis from indwelling catheters.
SVC can raise…
intracranial pressure leading to HAs, dizziness and increased risk of aneurysm/ruptureof intracranial arteries.
Lobar pneumonia typical organisms
-S. pneumoniae (most frequent) -Legionella -Klebsiella
Characteristics of lobar pneumonia
-intra-alveolar exudate leading to consolidation -may involve entire lung
Bronchopneumonia typical organisms
-S. pneumoniae -S. aureus -H. influenzae -Klebsiella
Characteristics of bronchopneumonia
-acute inflammatory infiltrates from bronchiles into adjacent alveoli -patchy distribution
Interstital (atypical) pneumonia organisms
-viruses (influenza, RSV, adenoviruses) -mycoplasma -legionella -chlamydia
Characteristics of interstitial pneumonia
-diffuse, patchy inflammation localized to interstitial areas at alveolar walls -generally follows indolent course
Lung abcesses are…
a localized collection of pus within parenchyma
Lung abscesses are caused by…
bronchial obstruction (cancer) or aspiration of oropharyngeal contents (esp in alcoholics or epileptics)
On CXR, lung abscesses often show…
air-fluid levels
Lung abscesses organisms
-S. aureus -anaerobes (bacteroides, fusobacterium, peptostreptococcus)
Lung abscesses should be treated with…
clindamycin because it covers S. aureus and anaerobes.
Pleural effusions are…
excess accumulation of fluid between the 2 pleural layers leading to restricted lung expansion during inspiration
Transudate features
-decreased protein content -due to CHF, nephrotic syndrome or hepatic cirrhosis
Exudate features
-increased protein content, cloudy -due to malignancy, collagen vascular disease, trauma
Lymphatic pleural effusions are also known as…
chylothorax. They are due to throacic duct injury from trauma or malignancy. -milky appearing fluid -increased trigs
Pneumothorax is…
accumulation of air in the pleural space
Pneumothorax symptoms
unilateral chest pain and dyspnea decreased tactile fremitus hyperresonance dimished breath sounds
Spontaneous pneumothorax occurs most commonly in..
tall, thin young males bc of rupture of apical blebs
Tension pneumothorax usually occurs in the setting of…
trauma or lung infection. Air is capable of entering pleural space but not exiting so trachea deviates away from affected lung.
