Robbins Chapter 13: Lungs Flashcards
Bronchial Tree
Bronchi–>bronchioles—>terminal bronchioles—> respiratory bronchioles—>alveoli duct—> alveolar sacs
Acinus
Respiratory bronchioles, alveolar ducts, alveolar sacs
ARDS
Rest failure occurring within 1 week of a known clinical insult w. bilateral opacities on chest imaging, not fully explained by effusions, atelectasis, CF, or fluid overload.it is a restrictive airway disease
ARDS symptoms
Integrity of alveolar-capillary membrane is compromised by endothelial and epithelial injury. There is respiratory insufficiency, cyanosis, severe arterial hypoxemia that is refractory to oxygen therapy.
Diffuse Alveolar Damage
histological manifestation of ARDS in the lungs.
Most frequent triggers of ARDS
pneumonia, sepsis, aspiration, trauma, pancreatitis, transfusion reactions
Acute Phase of ARDS
Capillary congestion, necrosis of alveolar epithelial cells, interstitial and intra-alveolar edema hemorrhage, collections of neutrophils in capillaries. Presence of hyaline membrane lining alveolar ducts
Organizing Stage of ARDS
Type II pneumocytes proliferate to regenerate alveolar lining.
Hyaline Membrane
fibrin rich edema and necrotic epithelial cells, intra-alveolar fibrosis. Line the alveolar ducts.
Poor Prognosis of ARDS
Advanced age, multi organ failure, bacteremia
Obstructive Airway Disease
Increase resistance to airflow caused by partial or complete obstruction at any level.
Restrictive Pulmonary Disease
Reduced expansion of lung parenchyma and decreased total lung capacity.
Types of obstructive disorders
- Emphysema
- Asthma
- Chronic Bronchitis
- Bronchiectasis
FEV1/FVC ratio in Obstructive disorders
FEV1/FVC ration is reduced. FEV1 is reduced and FVC is reduced or unchanged.
FEV1/FVC ration in Restrictive disorders
FEV1/FVC remains unchanged. FVC is reduced and FEV1 remains unchanged or is reduced proportionally.
Chronic Bronchitis initially affects..
the large airways
Emphysema affects..
the acinus.
COPD includes
chronic bronchitis and emphysema. It is irreversible
Emphysema
Permanent enlargement of air spaces distal to terminal bronchioles, accompanied by destruction of their walls without significant fibrosis.
Lobule
A cluster of 3-5 acinus
4 major types of emphysema
- Centriacinar/Centrilobular
- Panacinar
- Distal Acinar
- Irregular
Only Centriacinar and panacinar cause significant airway obstruction.
Centriacinar/Centrilobular Emphysema
Respiratory bronchioles are affected and distal alveoli are spared. More severe in apical segments of upper lobes. More common in cigarette smokers.
Panacinar/Panlobular Emphysema
All of acinus is affected. More severe in lower lobes. Associated with alpha1-antitrypsin deficiency.
Distal Acinar/Paraseptal Emphysema
Distal part of acinus is abnormal. It occurs adjacent to areas of fibrosis & is more severe in upper half of lungs. More often present in young adults with spontaneous pneumothorax.
Irregular Emphysema
Irregular portions of acinus affected. Associated with scarring. Asymptomatic and maybe the most common form of emphysema.
Pathogenesis of Emphysema
- Inflammatory cells & mediators
- Protease-antiprotease imbalance
- Oxidative stress
- Airway infection
Inflammatory cells & mediators in Pathogenesis of Emphysema
Imflamm mediators increase (e.g. leukotriene B4, IL-8, TNF, etc) - they attract more inflammatory cells in circulation, amplify inflammatory process, & induce structural changes w. growth factors.
Inflammatory cells present in emphysema lesions
Neutrophils, Macrophages, CD4+, CD8+ T cells
Protease-Antiprotease Imbalance
Proteases released from inflammatory cells & epithelial cells that break down CT. In Pts that Deve,op emphysema there is a deficiency of anti-proteases.
Oxidative Stress
ROS are generated from cigarette smoke & released from activated inflammatory cells (macrophages & neutrophils). Cause tissue damage.
Airway infection in emphysema
Bacterial and/or viral infections can exacerbate emphysema
Alpha1-antitrypsin
Present in serum, tissue fluid, macrophages. Inhibitor of proteases (particularly elastase) secreted by neutrophils during inflammation.
Proteinase Inhibitor (Pi)
locus on chromosome 14 that encodes for Alpha1-antitrypsin.
Protease mediates damage of…
Extracellular matrix.
Small airways held open by…
elastic recoil of lung parenchyma. Loss of elastic tissue in walls of alveoli that surround respiratory bronchioles reduces radial traction and causes respiratory bronchioles to collapse during expiration.
In emphysema there is loss of..
alveoli and alveolar capillaries.
First symptom in Emphysema
Dyspnea
FEV1/FVC ratio in Emphysema
Reduced, FEV1 reduced, FVC normal or reduced.
Pink Puffers
Name for emphysema patients. Puffers due to dyspnea and hyperventilation, Pink because they are well oxygenated w. Hb.
Classic presentation of emphysema w. no bronchitic component
Pt is barrel chested & dyspneic, thin, prolonged expiration, sitting forward in a hunched over position.