Respiratory Flashcards
When is respiration possible?
25 weeks
Pulmonary hypoplasia
Poorly developed bronchial tree with abnormal histology
Assoc w/ CDH and b/l renal agenesis
Bronchogenic cysts
Abnormal budding of the foregut and dilation of terminal or large bronchi
Club cells
Nonciliated; low-columnar/cuboidal with secretory granules
Located in small airways
Secrete component of surfactant; degrade toxins; act as reserve cells
Type I pneumocytes
97% of alveolar surfaces
Line the alveoli
Squamous; thin for optimal gas diffusion
Type II pneumocytes
Secrete surfactant from lamellar bodies
Cuboidal and clustered
Precursors to type I
Neonatal RDS
Surfactant deficiency -> alveolar collapse (ground glass on XR)
Therapeutic supplemental O2 SE in neonates
Retinopathy of prematurity
Intraventricular hemorrhage
Bronchopulmonary dysplasia
Screening tests for fetal lung maturity
L/S (≥ 2 is healthy)
Foam stability index test
Surfactant-albumin ratio
Conducting zone of respiratory tree anatomy
Large airways: nose, pharynx, larynx, trachea, and bronchi
Small airways: bronchioles further dividing into terminal bronchioles
Conducting zone of respiratory tree function
Warms, humidi es, and lters air but does not participate in gas exchange
Conducting zone of respiratory tree histology and components
Cartilage and goblet cells extend to end of bronchi
Pseudostrati ed ciliated columnar cells primarily make up epithelium of bronchus; transition to cuboidal cells
Respiratory zone of the respiratory tree anatomy
Lung parenchyma; consists of respiratory bronchioles, alveolar ducts, and alveoli
Respiratory zone of the respiratory tree function
Gas exchange
Respiratory zone of the respiratory tree histology
Mostly cuboidal cells in respiratory bronchioles, then simple squamous cells up to alveoli
Cilia terminate in respiratory bronchioles
Relation of the pulmonary artery to the bronchus
Right Anterior; Left Superior
Location of carina
Posterior to ascending aorta and anteromedial to descending aorta
Inhaled foreign body
Right lung: right main stem bronchus is wider, more vertical, and shorter
Basal segment if upright; posterior segment if supine
Where does the common carotid bifurcate?
C4
Where does the trachea bifurcate?
T4
Where does the abdominal aorta bifurcate?
L4
Tidal volume
Air that moves into lung with each quiet inspiration, typically 500 mL
Residual volume
Air in lung after maximal expiration
Elastic recoil
Tendency for lungs to collapse inward and chest wall to spring outward
Taut form of hemoglobin
Right shift of dissociation curve: ↑ O2 unloading
↑ Cl−, H+, CO2, 2,3-BPG, and temperature favor
taut form
Methemoglobin
Oxidized form of Hb (ferric, Fe3+); does not bind O2 as readily but binds cyanide (use to treat cyanide poisoning)
Normal iron state in Hb
Reduced (ferrous, Fe2+)
Methemoglobin presentation and treatment
Cyanosis and chocolate-colored blood
Methylene blue and vitamin C
Carboxyhemoglobin
Hb bound to CO in place of O2
↓ oxygen-binding capacity with left shift; ↓ O2 unloading
CO binds Hb 200x more than O2
Carboxyhemoglobin presentation and treatment
Geadaches, dizziness, and cherry red skin
100%/hyperbaric O2
Causes of right shift of O2/Hb curve
Acid CO2 Exercise 2,3-BPG Altitude Temperature
Physiological effects of a right shift
↓ affinity of Hb for O2 (↑ unloading of O2 to tissue)
Which way is a FHb curve shifted?
Left
[Hb], %O2 sat of Hb (SaO2), PaO2 and total O2 in anemia
SaO2: normal
PaO2: normal
Total O2: ↓
[Hb], %O2 sat of Hb (SaO2), PaO2 and total O2 in CO poisoning
SaO2: ↓
PaO2: normal
Total O2: ↓
[Hb], %O2 sat of Hb (SaO2), PaO2 and total O2 in polycythemia
SaO2: normal
PaO2: normal
Total O2: ↑
Response to high altitude
↓ Pao2 -> ↑ ventilation -> ↓ Paco2 -> respiratory alkalosis -> altitude sickness
↑ EPO, 2,3BPG, mitochondria, renal excretion of HCO3
Response to exercise
↑: CO2 production, O2 consumption, ventilation
↓: pH
Rhinosinusitis
Obstruction of sinus drainage into nasal cavity
Maxillary sinuses drain into middle meatus
Most common location of epistaxis
Anterior segment of nostril (Kiesselbach plexus)
Location of a life threatening nose bleed
Posterior segment (sphenopalatine artery, a branch of maxillary artery)
Sign of a PE
V ̇/Q ̇ mismatch, hypoxemia, respiratory alkalosi
Clinical presentation of a PE
Sudden-onset dyspnea, pleuritic chest pain, tachypnea, tachycardia
Flow volume loop in obstructive lung diseases
> volume (↑ TLC, FRC, RV); decreased FEV1/FVC
Loops shifts to the left
Flow volume loop in constrictive lung diseases
Increased FEV1/FVC
Loops shifts to the right
Pulmonary functions tests in obstructive lung diseases
↓↓ FEV1, ↓ FVC: ↓ FEV1/FVC ratio (hallmark)
V ̇/Q ̇ mismatch
Chronic bronchitis
Wheezing, crackles, cyanosis
Hypertrophy and hyperplasia of mucus-secreting glands (↑ Reid index >50%)
Dx: productive cough for > 3 months in a year for > 2 consecutive years
Emphysema types
Smoking: centriacinar (upper lobes)
α1-antitrypsin deficiency: panacinar, lower lobes
Emphysema pathology and clinical findings
Large air spaces
↓: recoil, Dlco
↑: compliance, elastase
↑: AP diameter, lucency; flat diaphragm, pursed lips
Asthma
↓ inspiratory/ expiratory ratio
mooth muscle hypertrophy and hyperplasia, Curschmann spirals, Charcot-Leyden crystals
Bronchiectasis
Purulent sputum, recurrent infections, hemoptysis, digital clubbing
Chronic necrotizing infection of bronchi
Poor ciliary motility (smoking, Kartagener), CF, ABPS
Restrictive lung diseases pulmonary tests
↓ lung volumes
FEV1/FVC ratio ≥ 80%
Interstitial lung diseases
Type of restrictive dz
↓ pulmonary diffusing capacity, ↑ A-a gradient
Pneumoconioses, Sarcoidosis, idiopathic, Wegners etc
Idiopathic pulmonary fibrosis
Restrictive lung dz
FEV1/FVC ratio ≥ 80%
↑ collagen deposition, “honeycomb” lung appearance and digital clubbing
Hypersensitivity pneumonitis
Type III/IV hypersensitivity reaction to environmental antigen
Seen in farmers and those exposed to birds
Inhalation injury and sequelae
Bronchoscopy shows severe edema, congestion of bronchus, and soot deposition (18 hours after inhalation injury; resolution at 11 days after injury)
Pneumoconioses sequelae
↑ risk of cor pulmonale, cancer, and Caplan syndrome (rheumatoid arthritis and pneumoconioses with intrapulmonary nodules)
Pneumoconioses types
Asbestos from the roof, but affects the base (lower lobes)
Silica and coal from the base (earth), but affect the roof (upper lobes)
Asbestosis
“Ivory white,” calcified, supradiaphragmatic and pleural plaques are pathognomonic
↑ risk of bronchogenic Ca, pleural effusion
Asbestos (ferruginous) bodies are golden-brown fusiform rods resembling dumbbells; found in alveolar sputum sample, visualized using Prussian blue stain
Berylliosis
Aerospace and manufacturing industries
Granulomatous (noncaseating); responds to steroids
Affects upper lobes
Anthracosis
asymptomatic condition found in many urban dwellers exposed to sooty air
Silicosis
Associated with foundries, sandblasting, mines
Macrophage release fibrogenic factors: fibrosis
Silica may disrupt phagolysosomes and impair macrophages, increasing susceptibility to TB
Affects upper lobes
“Eggshell” calci cation of hilar lymph nodes on CXR
Mesothelioma
Malignancy of the pleura associated with asbestosis
Psammoma bodies; cytokeratin and calretinin ⊕ in almost all mesotheliomas
Acute respiratory distress syndrome dx
Diagnosis of exclusion:
- respiratory failure within 1 week of alveolar insult
- bilateral lung opacities
- ↓ PaO2/FiO2 < 300 (hypoxemia due to ↑ intrapulmonary shunting and diffusion abnormalities)
- no evidence of HF/fluid overload
Acute respiratory distress syndrome pathology
Endothelial damage → ↑ alveolar capillary permeability → protein-rich leakage into alveoli → diffuse alveolar damage and noncardiogenic pulmonary edema → formation of intra- alveolar hyaline membranes
Sleep apnea
Cessation of breathing > 10 s
Hypoxia → ↑ EPO release → ↑ erythropoiesis
Central sleep apnea
No respiratory effort due to CNS injury/toxicity, HF, opioids
Cheyne- Stokes respiration
Obesity hypoventilation syndrome
Hypoventilation ↑ PaCO2 during waking hours
Pickwickian syndrome
Heritable PAH
Inactivating mutation in BMPR2 gene (normally inhibits vascular smooth muscle proliferation); poor prognosis
PE findings in pleural effusion
↓ breath sounds, dull percussion, ↓ fremitus
PE findings in atelectasis
↓ breath sounds, dull percussion, ↓ fremitus
Tracheal deviation toward lesion
PE findings in simple pneumothorax
↓ breath sounds, hyperresonant percussion, ↓ fremitus
PE findings in tension pneumothorax
↓ breath sounds, hyperresonant percussion, ↓ fremitus
Tracheal deviation away from lesion
PE findings in consolidation
Bronchial breath sounds, egophony, dull to percussion, ↑ fremitus
Transudate pleural effusion
↓ protein content
Due to ↑ hydrostatic pressure or ↓ oncotic pressure
Exudate pleural effusion
↑ protein content
Due to malignancy, pneumonia, collagen vascular disease, trauma (↑ vascular permeability)
Must be drained
Lymphatic pleural effusion
Due to thoracic duct injury from trauma or malignancy.
Milky- appearing fluid; triglycerides
Primary spontaneous pneumothorax
Due to rupture of apical subpleural bleb or cysts
Occurs most frequently in tall, thin, young males
Secondary spontaneous pneumothorax
Due to diseased lung
Tension pneumothorax
Air enters pleural space but cannot exit
Trachea deviates away from affected lung
Lobar pneumonia
S pneumo most frequently; also Legionella, Klebsiella
Intra-alveolar exudate → consolidation
Bronchopneumonia
S pneumoniae, S aureus, H influenzae, Klebsiella
Acute inflammatory infiltrates from bronchioles into adjacent alveoli; patchy distribution involving ≥ 1 lobe
Interstitial (atypical) pneumonia
Diffuse patchy inflammation localized to interstitial areas at alveolar walls; diffuse distribution involving ≥ 1 lobe
Cryptogenic organizing pneumonia
Noninfectious pneumonia characterized by inflammation of bronchioles and surrounding structure
⊝ sputum and blood cultures, no response to antibiotics
Lung abscess treatment
Clindamycin
Pancoast tumor
Superior sulcus tumor; occurs in the apex of lung
Compression of locoregional structures:
Recurrent laryngeal nerve: hoarseness
Stellate ganglion: Horner syndrome
Superior vena cava: SVC syndrome
Brachiocephalic vein: brachiocephalic syndrome (unilateral symptoms)
Brachial plexus: sensorimotor deficits
Superior vena cava syndrome
An obstruction of the SVC that impairs blood drainage from the head (“facial plethora”; note blanching) and UE
Histology of SCC
Neoplasm of neuroendocrine Kulchitsky cells: small dark blue cells
Chromogranin A ⊕, neuron-specific enolase ⊕
Adenocarcinoma of lung histology
Glandular pattern on histology, often stains mucin⊕
Adenocarcinoma
Most common lung cancer in nonsmokers and overall
Activating mutations include KRAS, EGFR, and ALK
Squamous cell carcinoma of lung histology
Keratin pearls and intercellular bridges
Guaifenesin
Expectorant—thins respiratory secretions; does not suppress cough re ex
N-acetylcysteine
Mucolytic—liquifies mucus in chronic bronchopulmonary diseases (eg, COPD, CF) by disrupting disulfide bonds
Dextromethorphan
Antitussive (antagonizes NMDA glutamate receptors)
