Atelectasis of the lung, Acute Lung injury, and Diseases of Vascular Origin
Disease
Atelectasis
Obstructive
Atelectasis
(Resorption)
Compression
Atelectasis
Contraction
Atelectasis
Atelectasis due to
loss of surfactant
Pathogenesis
- Incomplete expansion or collapse of previously inflated lung,
producing areas of relatively airless pulmonary parenchyma
- Can occur at birth or anytime afterwards
- Reversible, since collapsed lung can be reinflated
o Exception, scarring (contraction atelectasis
- Complete obstruction of an airway causes resorption of oxygen
distally through the pores of Kohn in alveoli
- Due to excessive bronchial secretions and mucous plugging
(bronchial asthma, chonic bronchitis, post-op complication)
- Tumors  incomplete obstruction and localized emphysema
 Mediastinum shifts toward lung
- Filled Pleural cavity (fluid, tumor, blood clot, air) partial or complete
o HF or neoplastic effusion  fluid compresses the lung
o Pneumothorax  Air compresses the lung
- Abnormally elevated diaphragm: basal atelectasis
o Peritonitis, subdiaphragmatic abscess or seriously ill post-op
 Mediastinum shifts away lung
- Local or generalized fibrotic changes
o Pleura / Lungs prevent expansion
- Ex. Respiratory Distress Syndrome (RDS) in Infants
-  Loss of surfactant
Surfactant normally prevents collapse
©2010 Mark Tuttle
Clinical
-
Labs/Histology
- Fever
- Ipsilateral elevation of the diaphragm
- Dyspnea
- Usually within 24
hours of collapse
- Absent breath sounds
-
- Ground-glass appearance on X-ray
Acute Lung Injury:
Pulmonary Edema
• Pulmonary congestion + edema
• Adult Respiratory Distress Syndrome (Diffuse alveolar damage b/c can be children too)
1. Hemodynamic edema(transudate) 2. Edema from Microvascular Injury (exudate)
- Hydrostatic pressure ↑
- Infections: pneumonia, septicemia
- Heavy, wet lungs,
o Left sided HF (common)
- Inhaled gases: oxygen, smoke
frothy blood tinged
o Volume Overload
- Aspiration: gastric contents, near-drowning
fluid
o Pulmonary vein obstruction
- Drugs/chemicals: chemotherapeutic agents
- Fluid accumulates
- Oncotic pressure ↓ (less common)
o Bleomycin: edema & fibrosis
Short term
Long-term
in the lower lobes
o Hypoalbuminemia
o Amphotericin B
Microscopic changes
where hydrostatic
o Nephrotic syndrome
o Heroi
- Intraalveolar granular eosinophilic precipitate
pressure is greater
o Liver disease
o Kerosine
- Alveolar microhemorrhages and hemosiderin- Changes lead to
o Protein-losing enteropathies
o Paraquat (herbicide)
laden macrophages (“heart-failure cells”) present
impaired function
- Lymphatic Obstruction
- Shock
in chronic cases
(interstitial edema)
- Trauma
- With long-standing chronic passive congestion
and predisposes
- Transfusion-related (TRALI)
(e.g. mitral stenosis – fish mouth from RF), lungs
one to infections
3. Edema of undetermined origin
become visibly brown. firm (hemosiderin-laden
(intraalveolar
- High Altitude (HAPE) – High altitude pulmonary edema
macrophages and interstitial fibrosis)
edema)
- Neurogenic (CNS trauma)
termed “brown induration”
Adult Respiratory
Infection
Chemical Injury
- Rapid onset of:
Acute Stage
Distress Syndrome
Sepsis (40% cases) Heroin or methadone o Severe life-threatening respiratory insuffic.
- Increased capillary permeability produces
(ARDS, Diffuse
Diffuse pulmonary Acetyaslicyclic acid
o Cyanosis
interstitial and then intra-alveolar edema
Alveolar Damage
infections
Barbituate overdose
o Severe arterial hypoxemia refractory to
- Interstitial inflammation
DAD)
Gastric aspiration Paraquat (herbicide)
oxygen therapy
- Hyaline membranes composed of fibrin rich
(30% cases)
o “White out” on X-ray - bilateral
fluid, cytoplasmic and lipid remnants of
Noncardiogenic
Inhaled Irritants
- Severe pulmonary edema
necrotic epithelial cells
pulmonary edema
Physical Injury
Oxygen toxicity
- Frequently progresses to multisystem failure
Organizing stage
resulting from acute
Mechanical
Smoke
Pathogenesis
- Resolution is unusual. Instead, the fibrin
alveolar-capillary
trauma(head )
Irritant gases and
- Diffuse damage to alveolar capillary walls
exudate organizes
damage
(20% cases)
chemicals
- Most common: alveolar capillary endothelium
- Hyperplasia of type II pneumocyte continues
Pulmonary
- Less common: injury to alveolar epithelium
– attempt at repair and resolution
Clinical Course
contusions
Hematologic
- Increased vascular permeability ↑
- Interstitial inflammation and fibrosis
- 150,000 cases/year
Near-drowning
Multiple transfusions  Alveolar flooding, rich in fibrin, deposit in wall
- Intra-alveolar fibrosis
in USA
Fractures with fat DIC
- Analogous to crescenteric glomerulonephritis
- Honeycomb lung
- 60% mortality
embolism
- Loss of diffusion capacity
Superimposed bacterial infx: in fatal cases
- Severe dyspnea +
Burns
Pancreatitis
- Widespread surfactant abnormalities due to
Diffuse Alveolar Damage (DAD)
tachypnea
Ionizing radiation
damage of Type II Pneumocytes Atelectasis
Hyaline membrane
- O2 transport dmgd
- Hypoxemia
Uremia
- Resolve in 1st week
unresponsive to O2
Hypersensitivity
- If survive > 1week,
therapy
Organic solvents
Cardiopulm bypass
Honeycomb
inflammation + fibros
- PaO2 < 50mmHg
Drugs
Lung
 compliance ↓
- Respiratory therapy
 V/Q mismatch
- Need high O2 to treat
but O2 toxicity
Diseases of Vascular Origin: Pulmonary embolisum, hemorrhage, infarction. Pulmonary HTN, vascular sclerosis, Diffuse pulmonary hemorrhage (Goodpasture, idopath)
Disease
Pathogenesis
Clinical
Labs/Histology
Pulmonary Embolism - Blood clot that occlude the large
None (~60-80% are clinically silent)
Embolus:
pulmonary arteries
- Too small of emboli
- Red cells, platelets and fibrin fill arterial
Large
- Source: DVT in legs (most common)
Hemorrhage (~10-15%)
lumen adhering to endothelial surface
- Chest pain
- Predisposing factors:
- Tissue viability sustained by collateral blood flow - May dissolve or organize and recanalize
- Dyspnea
o Immobilization (ex. hospital, flight)
- Transient chest pain & cough
Hemorrhage:
- Shock
o Hypercoagulable States
Infarction (10%) – less likely b/c collateral circul.
- Blood in alveoli and interstitium
- Fever
(Factor V bleeder, Contraception –
- Due to inadequate collateral blood flow; often
- Preserved architecture
- Elevated enzyme,
estrogen, Malignancy [Trousseau’s])
coexisting heart and lung disease is present
Infarct:
Acute R-HF (cor pulm.), CV collapse sudden death
- Usually wedge-shaped and peripheral, with
LDH3 ↑
Treatment
- Due to obstruction of pulmonary vasculature
embolus at apex
mimic MI
- Difficult problem: prophylaxis
- Patients have electromechanical dissociation
- Apex points to hilum
- Early post-surgical ambulation
Pulmonary hypertension
- ¾ infarcts in lower lobe
Small
- Elastic stockings, leg exercises
- Multiple emboli over time; can cause chronic
Acute (recent) infarct
- Transient chest
Anticoagulation
for
high-risk
ppl
right
heart
strain
(right
ventricular
hypertrophy)
- Coagulative necrosis with hemorrhage
pain or cough- Filter in inferior vena cava
Second embolus (30%)
(ie. red infarct)
normal CVS
- Overlying pleura with fibrinous pleuritis
- Dyspnea
- Post-morten clot: free, unattached
Seen in most cases
Remote (old) infarct
- Tachypnea
- Pre-morten clot: lines of Zahn, on vessel - Wheezing from THXA2 from platelets
- Inflammatory response followed by
- Chest pain
- Fever
regeneration and fibrosis (scar)
- Cough, hemoptysis
- Pleural friction rub
- Often hemosiderin in macrophagesHF cells
– infarcts with
Special types of Emboli
compromised
Pulmonary Infarct
Fat
embolism:
Air
embolism:
bronchial
- Multiple in > 50%
- Most common form of clinically
- Trauma, surgery, intravenous injections,
circulation
- Lower lobes: 2/3
significant embolism second to
obstetrical procedures, criminal abortion
- Wedge shaped
thromboembolism
May
cause
sudden
death
frothy
blood
is
Diagnosis
- Base peripheral
- Occurs generally as a result of fracture
present in the right ventricle and pulmonary
- Spiral CT
- Apex toward hilum
of a long bone, most typically the femur
artery at autopsy
angiography
- Histological examination shows fat
- On histological examination, empty spaces
- Most definitive
globules in the capillaries and small
resembling fat emboli are seen
technique, but
Saddle Embolus
vessels of the lung
Embolic carcinomatosis:
dangerous for the
Septic embolism:
- Carcinomas (breast, stomach and lung) invade
patient
- Infected fragments of venous thrombi or
blood vessels, disseminate and occlude
- D-dimer level
tricuspid valve vegetations (endocarditis)
pulmonary arteries
- “Septic infarct” (neutrophils and
Amniotic fluid embolism:
organisms) can convert to abscess
- Usually at time of delivery; can cause shock and
Bone marrow embolism:
diffuse alveolar damage in severe cases
- CPR with chest compressions leading to
rib fractures
Starch or talc particles:
- Contained in drug injected by addicts
Disease
Pulmonary
Hypertension
When mean
pulmonary pressure
reaches ¼ systemic
Pathogenesis
- Primary (Idiopathic) – rare
o Females: 24-40yrs; sometimes young
o Dyspnea, fatigue (hypoxia), common
o Some patients have angina
o Right ventricular hypertrophy
o 80% die 2-5 years of Cor Pulmonale
o Often w/emboli, pneumonia
- Secondary: Structural conditions which
increase pulmonary blood flow, vascular
resistance, or L heart resistance
o Chronic obstructive, insterstitial lung
diseases
o Antecedent congenital or acquired
heart disease (ex. TOF)
o Recurrent thromboemboli
o Autoimmune disorders
Diffuse Pulmonary Hemorrhage Syndromes
Goodpasture
- Anti-Basement Membrane Antibodies
Syndrome
- Simultaneous renal, pulmonary disease
- Proliferative rapidly progressive
glomerulonephritis
- Necrotizing hemorrhagic interstitial
pneumonitis
Idiopathic Pulmonary - Degeneration and hyperplasia of
Hemosiderosis
alveolar epithelial cells
- Cause unknown
Vasculitis-associated
hemorrhage
- Hypersensitivity angiitis
- Wegener’s Granulomatosis
- Lupus erythematosus (SLE)
Clinical
- Role of BMPR2 (Bone morphogenic prot)
Surface protein family TGF-β
Binds to cytokines
o Embryogenesis
o Cell proliferation & differentiation
o Apoptosis
- BMPR2 inhibition of proliferation
- If mutated  proliferation of sm. mm.
o 50% of familial 1° pulmonary HTN
o 26% of sporadic cases
o 2q33 locus association
Morphology
Atheromatous plaques
- Main elastic arteries
Medial hypertrophy, intimal proliferation, fibrosis
- Small arteries and arterioles
Plexogenic pulmonary arteriopathy
- Capillary tuft formation (“plexiform lesion”)
- Indicates severe and irreversible hypertension
- Males > Females; most cases in teens, 20s
- Patients generally present with hemoptysis,
focal lung consolidations and renal failure.
- Uremia common cause of death
- Trigger, initiating antibody is unknown.
- Viruses, smoking and exposure to hydrocarbons
(dry cleaning industry) may be cofactors
- Treatment – immunosuppressants and
plasmapheresis
- Cough, hemoptysis, anemia, weight loss
- Children and young adults
-
Labs/Histology
Mainly arterioles, small arteries
Medial thickness, intimal fibrosis, narrow lumen
- Immunofluorescence shows linear deposits
of immunoglobulins and complement on the
glomerular BM and in the alveolar septa
- Hemosiderin filled macrophages in alveoli
and hemosiderin in alveolar septa
o DDx from HF cells  HF cells not in septa
- Capillary dilatation and pulmonary fibrosis
-