Pulmonary Flashcards
Why is lung infarction a rare complication of PE?
Dual circulation from pulmonary and bronchial systems.
CF: CFTR is what type of transmembrane protein?
MC mutation?
ATP-gated
Delta F508 - this mutation leads to protein MISFOLDING and failure of glycosylation –> degradation
Aspiration: supine
Posterior segments of upper lobes and superior segment of lower lobes
Aspiration: upright
Right main bronchus – basilar segments of lower lobes.
MOA of pulmonary hypertension
Vasoconstriction due to pulmonary venous congestion
Pulmonary vascular bed responds to tissue hypoxia by doing what?
Vasoconstricting
Diverts blood away from underventilated regions to better-ventilated regions. Arterial resistance dec as tissue o2 content inc
MC GI disorder in patients with CF?
Pancreatic insufficiency
Viscous secretions in lumens of pancreas –> obstruction, inflam –> fibrosis
Inc risk for def in fat-soluble vit like vit K
FEV1/FVC decreased
Obstructive (obstruction reduces FEV1 more than FVC)
FEV1/FVC increased
restrictive
May also be normal bc both vol reduced proportionally
Decreased TLC/RV is seen in obstructive or restrictive lung disease?
Obstructive (TLC is inc or normal, primarily through expansion of RV)
RV progressively increases
Where is airway resistance highest in the respiratory tract?
Medium sized bronchi > trachea > bronchioles >terminal bronchioles
What is a normal A-a gradient? Increase occurs in what situations?
10-15mmHg
Normal with alveolar hypoventilation.
Inc: hypoxemia due to shunting (airway obstruction), V/Q mismatch, fibrosis (impaired diffusion)
Consider what lung cancer in smokers?
Squamous cell carcinoma. There are SCC pancoast tumors.
Small cell carcinoma also possible.
Hereditary pulm arterial HTN is due to an inactivating mutation of BMPR2 - AD, which causes what histologically?
Vascular smooth mm cell proliferation.
What is the main lipid component of lung surfactant?
DipalmitoylphosphatidylCHOLINE (DPPC)
What type of vessel has the highest resistance in the body and therefore has the highest drop in pressure across the vessel?
Arterioles
Contribute the largest part of total peripheral resistance (systemic vascular resistance)
Perfusion-limited equilibration of O2
Normal individual at rest, PE
Diffusion-limited equilibration of O2
emphysema, pulm fibrosis, exercise.
What are normal tracheal pO2, alveolar pO2, and alveolar pCO2?
Tracheal pO2 - 150
alveolar pO2 - 104
alveolar pCO2 - 40
Failure of alveolar gas to reach normal equilibrium point. Presents with approx equal composition of tracheal air and alveolar air.
Perfusion defect: poor alveolar perfusion
e.g. PE
Rheumatoid arthritis can cause what pulmonary problem?
Interstitial lung disease (pulm fibrosis)
How does ankylosing spondylitis cause hypoventilation?
Thoracic spine and costovertebral and costosternal junctions are involved, limiting chest wall expansion.
PE occurs in what vessel?
Pulmonary ARTERY
Asbestos exposure inc risk of what malignancies? How can you differentiate them grossly?
Bronchogenic adenocarcomina - peripheral lesions of the lung
Mesothelioma - pleural thickenings
Note: Using immunohistochemistry, CALRETININ can be demonstrated in both benign mesothelium and in malignant mesothelioma
Assoc with ferruginous bodies/fusiform rods
asbestos effects lower lungs. For a particle to affect the lower lungs it has to be <2.5 mew/micro meters.
Of the following, which is LAST to disappear as the epithelium changes along the respiratory tube?
Goblet cells, cilia, mucous glands, serous glands, cartilage
Cilia
Bronchi - have pseudostrat columnar ciliated epithelium + goblet cell, submucosal mucoserous glands and cartilage
Bronchioles, terminal broncholes, and resp bronchioles (simple cuboidal) lack goblet cells, glands and cartilage
Alveolar macrophages are responsible for helping to clear the lower lobes (alveolar sacs)
Impaired CFTR affects Cl, Na and H20 how in the respiratory and intestinal epithelia?
Sweat ducts?
Resp/intestine:
- Reduced - Cl secretion
- Increased - Na and h20 absorption
- Causes dehydrated mucus and more neg nasal transepithelial potential difference
Sweat:
- cant reabsorb Cl and Na –> high Na and Cl in sweat
- hyponatremia from excess salt wasting (salt supplements recommended)
Differentiate primary ciliary dyskinesia vs CF
Primary ciliary dyskinesia - dynein arm (9+2) defect –> impaired mucociliary clearance, situs inversus, immotile sperm, normal growth, low nasal NO levels. Bronchiectasis
CF - mutation in CFTR gene –> chronic sinopulm infx, panc insuff, absent vas def, failure to thrive
Where is PVR lowest during spirometry?
At the FRC.
Increased AND decreased lung volumes inc PVR.
V/Q scan for PE shows what
PERFUSION defect without ventilation defect
embolus prevents adequate blood perfusion to the affect areas of the lung
In DKA, if a patient presents with blood pH 7.27, what does this indicate?
Respiratory failure
Normally in DKA, metabolic acidosis is compensated for by resp ALKALOSIS (Kussmaul respirations). If DKA becomes severe enough, resp fatigue, dec mental status, and hypoventilation can cause superimposed respiratory ACIDOSIS
Elastases found in alveolar fluid are derived from what?
Infiltrating neutrophils and alveolar macrophages
What cell type makes up over 95% of the surface area of the alveoli?
Type I pneumocytes (Squamous cells)
What cell type secretes the major components of pulmonary surfactant (phospholipids and dipalmitoyl phosphatidylcholine)?
Help with regeneration of alveolar lining
Type II pneumocytes - cuboidal-shaped with electron dense lamellar bodies.
(lamellar bodies of type II pneumocytes store and release pulm surfactant)
Proteinases of the lung?
Antiproteinases of the lung?
Proteinases: elastase, cathepsin G, MMP
Anti-proteinases: a1-antitrypsin, a2-macroglobulin, TIMPS
Note: neutrophil elastase is inhibited by a1-antitrypsin
macrophage elastase is inhibited by TIMPs (tissue inhibitors of metalloproteinases)
Sputum showing eosinophils and Charcot-Leyden crystals is what condition? Immunological mechanism?
Extrinsic allergic asthma
Involves bronchial wall infiltration by eosinophils in response to IL-5 release by allergen-activated TH2 cells
What cell contributes to the development of emphysema?
Neutrophils and macrophages - release proteases that degrade the ECM and generate oxygen free radicals that impair protease inhibitors (eg a1-antitrypsin)
How can silicosis lead to increase suspectibility to mycobacteria infection?
SIlicosis impairs the macrophage effector arm of cell-mediated immunity
Macrophage phagolysosomes may be disrupted by internalized silica particles
Superior vena cava syndrome can be caused by what? Sx?
Mediastinal mass (eg intrathoracic spread of bronchogenic carcinoma) Impaired venous return to upper body --> dyspnea, facial swelling, and dilated collateral veins in upper trunk
What is a major RF for ARDS? What happens to lung compliance, work of breathing, V/Q, and PCWP?
pancreatitis
Lung compliance - dec
work of breathing - inc
V/Q - mismatch
PCWP - normal (noncardiogenic pulm edema. Elevated PCWP is a sign of cardiogenic pulm edema like w/decomp LV failure)
Histo - activated neutrophils in alveolar tissue –> alveoli lined with hyaline membranes
Differentiate fat embolism sx from PE
Fat embolism - resp distress, NEURO sx (alt mentation, seizures), PETECHIAL RASH
PE - resp distress, tachypnea, tachy, cough, pleuritic chest pain, V/Q mismatch
Law of Laplace
Distending pressure (P) = 2T/r
T = surface tension
r = radius
Eg smaller spheres collapse before large ones
Surfactant counteracts alveolar collapse by dec surface tension as alveolar radius dec
What ratio indicates adequate surfactant production in a neonate?
L/S >=2
L = Lecithin (phosphatidylcholine)
S = Sphingomyelin (constant in 3rd tri)
Obesity can cause restrictive PFTs. MC indicator of obesity-related disease?
reduction in expiratory reserve volume and functional residual capacity
Primary mediators of disease in COPD?
Neutrophils, macrophages, and CD8 T lymphocytes. Secrete enzymes and proteases.
Note: inflam cells show impaired ability to phag bacteria also
What is the intrapleural pressure in the lung at FRC (ie resting state)
-5 cm H20
Note: chest wall has expanding force on lung –> neg pressure
Lungs, due to elasticity have positive transmural pressure, tendency to collapse
High altitude does what to pH, pCO2 and pO2?
Resp alkalosis (hyperventilation d/t hypoxia) - compensated by renal excretion of bicarb in 24-48h
pH inc
pCO2 dec
pO2 dec
In what situations is Diffusing capacity for carbon monoxide (DLCO) high or low?
High - asthma (inc pulm capillary blood vol)
Low - emphysema (destruction of alveoli and adjoining capillary beds)
Note: DLCO helps distinguish bw intrinsic vs extrinsic (eg obesity) restrictive lung diseases. Intrinsic has reduced DLCO, extrinsic has normal DLCO.
Unilateral pulmonary opacification and deviation of the mediastinum toward the opacified lung is characteristic of what?
Obstruction in a mainstem bronchus. (eg central lung tumors in chronic smokers)
Prevents ventilation of an entire lung –> obstructive atelectasis or complete lung collapse
Erythema nodosum, arthralgias, hilar lymphadenopathy, and elevated serum ACE levels are common findings in what? Liver histo?
Sarcoidosis
Histo - scattered noncaseating granulomas
Pneumoconiosis: eggshell calcification on rim of hilar nodes, birefringent particles surround fibrous tissue on histology
Silicosis
Most prominent in apical regions
Silica may disrupt phagolysosomes and impair macrophages –> inc risk for Tb
Pneumoconiosis: histo of nodal and perilymphatic lung tissue shows accumulations of macrophages filled with what?
Coal
Coal worker’s pneumoconiosis
Pneumoconiosis: noncaseating epithelioid granulomas without obvious particles on histo
Berylliosis
Pneumoconiosis: pleural plaques, assoc with mesothelioma
Asbestosis
How can excessively high O2 concentrations in patients with COPD precipitate confusion and depressed consciousness?
inc O2 –> inc CO2 retention (o2-induced hypercapnia) –> confusion and depressed consciousness.
Partly d/t reversal of hypoxic pulm vasoconstriction which inc physiologic dead space as the poorly ventilated alveoli are perfused .
How can you differentiate diffuse alveolar damage from bronchiolitis obliterans organizing pneumonia?
Diffuse alveolar damage (DAD)—> Increase alveolar capillary permeability—> protein rich leakage into alveoli—->formation of alveolar hyaline membranes.
Bronchiolitis obliterans is an inflammatory obstruction of the lung’s tiniest airways, called bronchioles. The bronchioles become damaged and inflamed by chemical particles or respiratory infections, particularly after organ transplants, leading to extensive scarring that blocks the airways.
Pulm circulation has what characteristic compared to bronchial circulation
Bronchial Arteries branch from the aorta to supply the bronchi and pulmonary connective tissue w/ nourishing, they receive 0.2-1.9% of C.O
Meanwhile, Pulmonary circulation receives the rest of the cardiac output.
Shunt vs dead space? Which is a PE?
SHUNT= airway obstruction (V/Q=0)
DEAD SPACE= blood flow obstruction (V/Q=infinity)
PE is an example of dead space
Smoking does what to the following:
- Mucus production/secretion
- Cilia activity
- Alveolar macrophage function
- Mucus production/secretion: inc
- Cilia activity: dec
- Alveolar macrophage function: dec
In neonatal resp distress syndrome, what structure is altered in the type II pneumocytes, resulting in less surfactant?
lamellar bodies, keratinosomes or Odland bodies are secretory organelles found in type II pneumocytes and keratinocytes.
A healthy patient inhales to total lung capacity and then exhales forcefully. The rate of expiratory airflow is highest at TLC and dec linearly as exhalation continues. Why?
Airway compression - limits flow.
Normal: after a small amount of gas has been exhaled, the flow is limited by airway compression and determined by the elastic recoil of the lung and resistance upstream of that point.
Restrictive: the maximum flow rate is reduced, as is the total volume expired. The flow is abnormally high in the latter part of expiration because of increased recoil.
Obstructive: the flow rate is very low in relation to lung volume, and a scooped out appearance is often seen following the point of maximal flow.
What happens to DLCO after ARDS (form of non-cardiogenic pulm edema) resolves
Dec DLCO - pulmonary edema increases the thickness of the alveolo-capillary space, increasing the distance the oxygen must diffuse to reach blood. This impairs gas exchange leading to hypoxia, increases the work of breathing, eventually induces FIBROSIS OF THE AIRSPACE.
The hallmark of ARDS is diffuse injury to cells which form the alveolar barrier, surfactant dysfunction, activation of the innate immune response, and abnormal coagulation.[1] In effect, ARDS results in impaired gas exchange within the lungs at the level of the microscopic alveoli.
Middle-aged woman with progressive shortness of breath?
Think of idiopathic pulmonary fibrosis, a restrictive lung disease.
