Pulmonology Flashcards
At what week does the distal end of the respiratory diverticulum become the lung bud
4 weeks
Note - Error at this state (embryonic) leads to TE fistula
Pulmonary hypoplasia (esp right lung) Limb deformities Facial anomalies
Potter sequence
Caused by oligohydramnios secondary to... Bilateral renal agenesis ARPKD Obstructive uropathy Chronic placental insufficiency
Chronic respiratory infections and discrete, round, sharply defined air-filled densities on CXR
BRONCHOGENIC CYST
Note - Caused by congenital dilation of large or terminal bronchioles
Cuboidal and clustered - secrete pulmonary surfactant made of phosphatidylcholine (lecithin; 30 wks) and phosphatidylglycerol (36 wks) to decrease lung recoil and increase compliance
TYPE II PNEUMOCYTES
Serve as precursors to Type I (squamous for gas exchange)
Note - Cover less surface area but are more plentiful than Type I pneumocytes
Nonciliated and cuboidal with secretory granules - degrade toxins
Club cells
Ground-glass appearance of lung fields with L/S < 1.5
Associated with…
Prematurity
Maternal diabetes (increased fetal insulin)
C-section (decreased fetal glucocorticoids)
Note - Fetal lungs mature when L/S > 2
NEONATAL RESPIRATORY DISTRESS SYNDROME
Treat with…
Maternal steroids
Artificial surfactants
May result in…
Metabolic acidosis
PDA (low O2 tension)
Necrotizing enterocolitis
Note - Retinopathy, IVH, and bronchopulmonary dysplasia if given supplemental O2
Includes cartilage, goblet cells, and pseudostratified columnar epithelium.
Bronchi
Note - Become serous fluid from club cells after this
Includes club cells and simple ciliated columnar epithelium.
Bronchioles
Note - Smooth muscle thickest here
Includes club cells and cuboidal ciliated cells
Respiratory bronchioles
Anatomic relationship of pulmonary artery to bronchus
“RALS”
Right anterior to bronchus
Left superior to bronchus
Vertebral levels of structures perforating diaphragm…
IVC
Esophagus/Vagus
Aorta, thoracic duct, azygous vein
T8 (directly enters RA)
T10
T12
Bifurcations of abdominal aorta, trachea, and common carotid
“rule of biFOURcation”
Abdominal aorta = L4
Trachea = T4
Common carotid = C4
Inspiratory capacity
IRV + TV
IRV = Room in lungs after normal inspiration TV = Air in lungs after normal inspiration
Functional residual capacity - Volume of gas after normal expiration
ERV + RV
ERV = Air that can still be breathed out after normal expiration RV = Air in lungs after maximal expiration
Vital capacity - Maximum volume of gas that can be expired after a maximal inspiration
IRV + TV + ERV
Total lung capacity - Maximum volume of gas present after a maximal inspiration
IRV + TV + ERV + RV
Physiologic dead space (VD)
(“Taco PAco PEco PAco”)
Note - Maximal alveolar dead space at lung apices
VT x [ (PaCO2 - PeCO2)/PaCO2 ]
VT = Tidal volume (normally around 500) Pa = Arterial PCO2 Pe = Expired air PCO2
Note - Normally around 150
Ventilation without perfusion
Pathologic dead space
Minute ventilation (VE)
VT x RR
Alveolar ventilation (VA)
(VT - VD) x RR
At FRC…
Airway/alveolar pressures
IP pressure
PVR
0
Negative
Minimum
Lung inflation results in lower volume at same pressure compared to lung deflation - due to need to overcome surface tension in inflation
Hysteresis
Factors favoring taut hemoglobin - low O2 affinity shifts curve to the right (offloading)
Increased... pH (H+ buffer) CO2 Exercise 2,3-BPG Altitude Temperature
Note - Results in renal hypoxia and increased EPO (erythrocytosis)
Note - 2,3-BPG is increased in hypoxia as its role is to bind Hb and enhance release
Mechanism of placental O2 transfer
HbF (2a, 2y) has a higher affinity for O2 due to decreased affinity of 2,3-BPG - drives oxygen across placenta to fetus
Mechanism of Methylene blue therapy for Methemoglobinemia
Methylene blue picks up electron from NADPH MetHb reductase and transfers it to MetHb - reduces Fe3+ back to Fe2+
Note - Do not give in G6PD deficiency (no NADPH)
Mechanism of CO induced left shift in Hb curve
CO binds with great affinity than O2, and therefore decreases offloading due to positive cooperativity
Note - On a blood oxygen content (not saturation) graph the result is a shift down
Normal Hb concentration
Decreased O2 sat
Normal PaO2 (dissolved O2)
Decreased total O2 content
CO POISONING
Decreased Hb concentration
Normal O2 sat
Normal PaO2 (dissolved O2)
Decreased total O2 content
ANEMIA
Increased Hb concentration
Normal O2 sat
Normal PaO2 (dissolved O2)
Increased total O2 content
POLYCYTHEMIA
Pa equilibrates with PA early along capillary - diffusion can only be increased by increasing blood flow
PERFUSION LIMITED GAS
Includes O2 in a healthy adult (high DLCO), CO2, N2O
Pa does not equilibrate fully with PA by the time blood reaches the end of the capillary
DIFFUSION LIMITED GAS (LOW DLCO)
Includes O2 in emphysema (decreased area), fibrosis (increased thickness), CO
Note - Exercise results in similar situation but DLCO is not decreased
PVR equation
[ P(pulm artery) - P(LA) ]/CO
Note - R = dP/Q
Alveolar gas equation - used for A-a gradient
PAO2 = 150 - (PaCO2/0.8)
Note - Normal A-a gradient = 10-15
Area of lung with highest and lowest V/Q
V/Q highest at apex (3; wasted ventilation)
Lowest at base (< 1; wasted perfusion)
Note - Both V and Q are maximal at the base and minimal at the apex, but Q drops more rapidly than V as you approach apex
Note - Apex ratio approaches 1 during exercise due to increased CO
V/Q = 0
SHUNT
Ventilation is 0 so O2 does not improve PaO2 (e.g. aspiration)
V/Q = infinity
DEAD SPACE
Perfusion is 0 so O2 does improve PaO2 (e.g. PE)
In a PE perfusion is distributed to nearby inflamed regions (poor ventilation) resulting in a R to L shunt (hypoxia) - Hyperventilation lowers CO2 but cannot raise O2
Causes of hypoxemia by normal and elevated A-a gradient
Normal:
High altitude
Hypoventilation
Elevated:
V/Q mismatch
Low DLCO
R to L shunt
Methods (3) of CO2 transport
HCO3- (90%)
Binding at N-terminus of globin (not heme and forming HbCO2 - favors taut form
Dissolved CO2
Haldane effect
In lungs oxygenation of Hb promotes H+ and CO2 offloading
Bohr effect
In tissue elevated PCO2 and H+ promote O2 offloading
Enzyme responsible for converting CO2 to H2CO3 - generates an H+ to bind Hb
Note - HCO3- is secreted from the cell via a HCO3-Cl antiporter
CARBONIC ANHYDRASE
Mechanism of RVH in high altitudes
Chronic hypoxic pulmonary vasoconstriction resulting in pulmonary hypertension
Risk factors for head and neck cancer
Alcohol
Tobacco
HPV-16 (oropharyngeal)
EBV (nasopharyngeal)
Acute and long term management of DVT
Acutely Heparin or LMWH (e. Enoxaparin)
Long-term oral anticoagulants (e.g. Warfarin, Rivaroxaban)
Hypoxemia
Neurologic abnormalities
Petechial rash (neck, axilla)
Thrombocytopenia
FAT EMBOLISM
Air trapping resulting in... Decreased FEV1/FVC (< 70%) Markedly decreased FEV1 Decreased FVC Increased RV (and FRC, TLC) Increased expiratory phase
Flow-volume loop…
Shifts to the left (larger volumes)
Decreases in size (reduced FEV and FVC)
OBSTRUCTIVE LUNG DISEASE
Includes COPD, asthma, and bronchiectasis
Note - Slow, deep breaths to decrease work of breathing against airway resistance
Interdigitating areas of pink (platelets, fibrin) and red (RBCs) found only in thrombi formed before death
LINES OF ZAHN
Productive cough for > 3 m/yr for > 2 yrs Wheezing Crackles Early hypoxemia (shunt) - elevated EPO Eventually hypercarbia Reid index > 40% Normal DLCO
Note - Reid index measures mucus gland enlargement
CHRONIC BRONCHITIS
Blue bloater - Hyperplasia of mucus-secreting glands in bronchi, inflammatory infiltrates, and squamous metaplasia
Two types of emphysema
Centriacinar - Upper lobes in smokers
Panacinar - Lower lobes in A1AT deficiency (+cirrhosis)
Mechanism of emphysema
Increased elastase (macrophage, neutrophils) activity
Increased compliance (inspiration)
Decreased recoil (expiration)
Hyperinflation
Dynamic airway obstruction during expiration
Decreased DLCO
Note - “Puffing” is to keep airway pressure elevated and prevent airway collapse during respiration
Shed epithelium forming whorled mucous plugs in asthma patients
Curschmann spirals
Eosinophilic, hexagonal needle-like crystals in sputum of asthma patients
CHARCOT-LEYDEN CRYSTALS
Formed from breakdown of eosinophils
Purulent sputum Recurrent infections Hemopytisis Digital clubbing Permanently dilated airways on CT
BRONCHIECTASIS
Chronic necrotizing infection of bronchi associated with…
Obstruction
Poor ciliary motility (smoking, Kartagener)
Cystic fibrosis
Allergic bronchopulmonary aspergillosis (CF, Asthma)
FEV1/FVC > 80
Decreased FEV1
Decreased FVC
Decreased TLC
Flow-volume loop…
Shifts to the right (smaller volumes)
Decreases in size (reduced FEV and FVC)
RESTRICTIVE LUNG DISEASE
Fast, shallow breaths to decrease work against elastic resistance of lungs
Increased FEV1/FVC due to increased radial traction increasing diameter of airways
Includes…
Idiopathic pulmonary fibrosis Poor breaching mechanics (normal DLCO, A-a gradient) ARDS NRDS/hyaline membrane disease Pneumoconioses Hypersensitivity pneumonitis Sarcoidosis
Bilateral hilar lymphadenopathy
Noncaseating granulomas
Asteroid bodies ("centriole-like")
Schaumann body (calcium in giant cells)
Uveitis
Cutaneous nodules
Increased ACE
Hypercalcemia due to increased ACE and 1,25 vit DSARCOIDOSIS
Note - CD4+ predominance which drives granuloma formation
Honeycomb CT
Lower lobe reticulonodular opacities on CXR
Digital clubbing
Restrictive PFTs
IDIOPATHIC PULMONARY FIBROSIS
Repetitive cycles of lung injury and TGF-b mediated healing resulting in increased collagen deposition - Neutrophil predominance
Farmer or birdkeeper with... Dyspnea Cough Chest tightness Granulomatous inflammation with eosinophils
HYPERSENSITIVITY PNEUMONITIS
Mixed Type III/IV hypersensitivity reaction to thermophilic Actinomyces - CD8+ predominance
Lower lobe pleural plaques
Pleural effusion
Golden-brown fusiform rods resembling dumbbells visualized with Prussian blue
ASBESTOSIS
Noncaseating granulomatous in upper lobes with hilar nodes - common in aerospace and manufacturing workers
BERYLLIOSIS
May respond to steroids
Macrophages laden with carbon in upper lobes - inflammation and fibrosis
COAL WORKERS PNEUMOCONIOSIS
Histologically similar to Anthracosis - asymptomatic in urban dwellers
Eggshell calcification of hilar lymph nodes affecting upper lobes - Common in foundries and mines
SILICOSIS
Silica disrupts phagolysosomes increasing risk for TB
Causes of (“SPPARTAS”)…
Impaired alveolar gas exchange and respiratory failure
Acute onset respiratory failure
No evidence of HF/fluid overload
Decreased PaO2/FiO2 (< 200)
Bilateral lung opacities (white out) on CXR
Can get waxy hyaline membrane
Caused by... Sepsis Pancreatitis ( large release of cytokines and enzymes cause activation of neutrophils in alveolar tissues) Pneumonia Aspiration uRemia Trauma Amniotic fluid embolism Shock
ACUTE RESPIRATORY DISTRESS SYNDROME
Trauma that results in bilateral pulmonary contusions or fat embolism following long bone fractures
cause INJURY TO ALVEOLAR PNEUMOCYTES and the PULMONARY ENDOTHELIUM –> release of inflammatory cytokines –> recruit neutrophils to the lung –> inflammatory mediators are released and cause further inflammation and alveolar endothelial damage causing:
1) increased pulmonary capillary permeability and fluid entry into the alveoli
2) decreased surfactant production causing alveolar collapse
3) protein rich fluid and necrotic debris causing hyaline membrane formation
Treatment of ARDS
Mechanical ventilation with low TV
Mechanism of ARDS
Endothelial damage (neutrophils, ROS, coagulation)
Increased alveolar capillary permeability
Protein-rich leakage into alveoli (hyaline membranes)
Diffuse alveolar damage
Non-cardiogenic pulmonary edema (normal PCWP)
Mechanism of pulmonary arterial hypertension - Presents as loud S2, systolic ejection murmur, right ventricular heave
Note - Defined as > 25 mmHg
Autosomal dominant BMPR2 mutation
Endothelial dysfunction
Medial hypertrophy and intimal fibrosis (onion skinning)
Plexiform capillary formation
Group I pulmonary hypertension
PULMONARY ARTERIAL HYPERTENSION (PAH)
Idiopathic Heritable (BMPR2 mutation causing smooth muscle proliferation) Drugs Connective tissue disease HIV Portal hypertension Congenital heart disease Schistosomiasis
Group II pulmonary hypertension
LEFT HEART DISEASE
Group III pulmonary hypertension
LUNG DISEASE/HYPOXIA
Group IV pulmonary hypertension
CHRONIC THROMBOEMBOLIC
Difference between pleural effusion and atelectasis (bronchial obstruction) on physical exam
Tracheal deviation is towards side of lesion in atelectasis
Note - Both have decreased breath sounds, dullness to percussion, and decreased fremitus
Light’s criteria
Exudative if…
Pleural/serum protein >0.5
Pleural/serum LDH >0.6
Pleural LDH > 2/3 upper limit for serum LDH
Common causes of exudative pleural effusion
Malignancy
Pneumonia
Collagen vascular disease
Trauma
Note - Increases risk of empyema
Thin, tall, young male with sudden onset chest pain
PRIMARY SPONTANEOUS PNEUMOTHORAX
Due to rupture of apical subpleural blebs or cysts
Note - Secondary due to diseased lung (e.g. bullae in emphysema, infections) or barotrauma (mechanical ventilation)
CXR appearance of…
Lobar pneumonia
Bronchopneumonia
Atypical pneumonia
Consolidation restricted to one lobe or lung
Patchy consolidation within a lobe or lung
Diffuse distribution along alveolar walls
Note - Bronchopneumonia is acute inflammatory infiltrate in alveoli from adjacent bronchioles
Bacterial etiology and treatment of air-fluid level in right lung
Note - Typically follows aspiration pneumonia
LUNG ABSCESS
Anaerobes (Bacteroides, Fusobacterium, Peptostreptococcus) or S. aureus
Treat with Clindamycin
Note - If upright will be right base, if supine will be superior segment of right lower lobe or posterior segment of upperlobes
Cancer with…
Psammoma bodies
Cytokeratin
Calretinin
Mesothelioma
Hoarseness (recurrent laryngeal)
Horner (superior cervical ganglion)
SVC syndrome
Sensorimotor deficit/arm pain (C8-T2)
PANCOAST SYNDROME
Smoker with... Undifferentiated central neoplasm Neuroendocrine origin Kulchitsky cells - small, dark blue cells Chromogranin A+ Neuron-specific enolase+ Myc oncogene Stain via neuro cell adhesion molecule (NCAM or CD56)
May cause... Cushing's SIADH Lambert-Eaton CNS dysfunction
SMALL CELL CANCER
Chemotherapy/Radiation
Non-smoker with... Peripheral glandular neoplasm Mucin+ KRAS EGFR ALK
May cause... Hypertrophic osteoarthropathy (clubbing)
ADENOCARCINOMA
Subtypes
Note - Most common form overall
Adenocarcinoma caused by growth along alveolar septa - thickening of alveolar wall with hazy infiltrates on CXR
Note - Better prognosis
BRONCHOALVEOLAR ADENOCARCINOMA (ADENOCARCINOMA IN SITU)
Smoker with…
Central hilar mass arising from the bronchus
Cavitation
Keratin pearls and intercellular bridges
May cause…
Hypercalcemia
SQUAMOUS CELL CARCINOMA
Peripheral highly anaplastic undifferentiated tumor
Pleomorphic giant cells
Elevated b-hCG
Gynecomastia
Galactorrhea
LARGE CELL CARCINOMA
Less responsive to chemotherapy so poor prognosis - remove surgically
Non-smoker with…
Pulmonary nest of neuroendocrine cells
Chromogranin A+
May cause…
Carcinoid syndrome
BRONCHIAL CARCINOID TUMOR
Excellent prognosis
Relationship of chest and lung compliance at FRC
Negative transmural pressure by chest wall (perpetually expanding) is balanced by positive transmural pressure by lung (perpetually collapsing)
Results in a resting airway pressure of 0 and intrapleural pressure of -5
Nerve under the piriform recess - damage leads to decreased supraglottic sensation and decreased cough reflex
INTERNAL SUPERIOR LARYNGEAL NERVE
Sensory afferent fibers (X) of the cough reflex (larynx, epiglottis) - efferents by motor portion of X
Markedly decreased ERV Normal RV Decreased FRC (ERV + RV) Decreased TLC Decreased FEV1 (< 80%) Decreased FVC (< 80%)
OBESITY-RELATED RESTRICTIVE LUNG DISEASE
Location of inferior border of lung/visceral pleura and parietal pleura…
Mid-axillary
Mid-clavicular
Paravertebral
6th rib and 8th rib
8th rib and 10th rib
10th rib and 12th rib
Note - Potential space between these two pleura is the costodiaphragmatic recess
Note - Always enter above a rib to avoid damaging intercostals lying underneath rib
Mechanism of decreased cerebral blood flow in hyperventilation (e.g. panic attack)
Decreased CO2 - potent cerebral vasodilator
Mechanism for minimum pulmonary vascular resistance at FRC
Inspiration stretches alveolar capillaries increasing their length and reducing their diameter, increasing their resistance
Expiration reduces tenting of extra-alveolar vessels and increases intrathoracic pressure on them, increasing their resistance
Profuse epistaxis in an adolescent male
Angiofibroma
Pleomorphic epithelial cells
Keratin+
Lymphocytic infiltration
Cervical adenopathy
Nasopharyngeal carcinoma
Hoarseness
Single vocal cord nodule in adults, multiple in children
Associated with HPV 6, 11
Laryngeal papilloma
Rarely may progress to laryngeal carcinoma - associated with alcohol and smoking
Four stages of lobar pneumonia
Note - Most common S. Pneumo, Klebsiella
Congestion
Red hepatization (neutrophils, RBCs)
Grey hepatization
Resolution (TII pneumocytes)
Most common causes (5) of bronchopneumonia…
Secondary, abscess, empyema Secondary, COPD CF Community, COPD Community, COPD, immunocompromised
S. aureus HIB Pseudomonas Moraxella Legionella
Most common causes (6) of atypical pneumonia…
Young adults (2) Infants Post-transplant Elderly Vet/Farmer with high fever
Mycoplasma (IgM hemolytic anemia), Chlamydia RSV CMV Influenza Coxiella (Q fever)
Timeline of TB infection
Hilar nodes, lower lobe Ghon focus with primary infection
Calcified Ranke’s complex with healing
Apical caseating granulomas (central necrosis, Langerhans giant cells) with secondary activation
Most common locations for miliary TB
Basal meningitis
Cervical lymph nodes
Sterile pyuria
Pott’s
Unilateral sided facial swelling
Unilateral sided arm swelling
Unilaterally distended jugular vein
BRACHIOCEPHALIC OBSTRUCTION
Unilateral unlike SVC syndrome which is bilateral
Note - Brachiocephalic also receives right lymphatic duct
Acidosis
High PCO2
Normal HCO3-
ACUTE RESPIRATORY ACIDOSIS
Renal compensation does not occur until after at least 24-48 hours of respiratory derangement
Mechanism of oxygen-induced hypercapnia
Pulmonary vasodilation increases dead space ventilation
Decreased chemoreceptor activity decreases minute ventilation
Decreased Hgb affinity for CO2 (Haldane effect) increases pCO2 levels
Anterior mediastinal masses
Thymoma
Teratoma
Thyroid cancer
Lymphoma
Respiratory quotient
CO2 produced/O2 consumed
Note - Typically around 0.8
Laplace’s law and surfactant
Distention pressure is the pressure needed to prevent collapse…
DP = 2T/r so as radius decreases DP increases - Surfactant decreases T with r to prevent an increase in DP
Resistance vessels of lower airway
Maximum resistance at medium sized bronchioles - Resistance lowers down the tree with increasing surface area
Differentiating hemithorax opacification by obstruction from pleural effusion
Obstruction - Mediastinal shift towards collapsed lung
Effusion - Mediastinal shift away from effusion
Collateral circulation of the lung
Bronchial arteries supply the bronchioles and then rejoin the pulmonary vein - This slightly lowers the PO2 in the outgoing pulmonary veins
Note - Collateral circulation results in hemorrhagic infarction rather than ischemic infarction in PE
Relationship of Palv, Part, Pv in zones of the lung
Zone 1 - Collapsed capillary (pathologic; apex)
Zone 2 - Pulsatile flow
Zone 3 - Continuous flow
Zone 1 - Palv > Part > Pv
Zone 2 - Part > Palv > Pv
Zone 3 - Part > Pv > Palv
Note - In supine position entire lung is zone 3
Sweat of a CF patient
Intestinal/Resp
higher Na and Cl ( due to CFTR and ENaC, diminished salt resorption)
Low Na and Cl ( decreased Cl secretion and increased Na absorption)
Eosinophils and mast cells
leukotrienes C4,D4,E4
bronchial asthma
induce bronchospasm and increasing bronchial mucus secretion
