L5 ATELECTASIS Flashcards
INTRODUCTION
DEFINITION;
Refers to either
1. Incomplete expansion of the lungs (Neonatal atelectasis)
2. A collapse of previously inflated lung producing areas of AIRLESS PULMONARY PARENCHYMA (Acquired Atelectasis)
No 2 occurs more commonly in adults and divider into
A. Resorption or obstruction Atelectasis
B. Compression Atelectasis
C. Contraction Atelectasis
RESORPTION ATELECTASIS
—This results from complete obstruction of an airway, leading to resorption of oxygen trapped in the dependent alveoli but without impairment of blood flow through the affected alveolar walls
— Thus because the lung volume is diminished the mediastinum shifts towards the atlectatic lung
—The causes include:
1.Excessive secretions (e.g., mucus plugs).
2.Exudates within smaller bronchi.
This condition is seen in the following states: -bronchial asthma, -chronic bronchitis, -bronchiectasis, -postoperative states, -aspiration of foreign bodies and, rarely, -bronchial neoplasms.
COMPRESSION ATELECTASIS
—This results from the pleural cavity being partially or completely filled by either:
1.Fluid exudate
2.Tumor.
3. Blood.
4. Air ( pneumothorax or tension pneumothorax).
The mediastinum shifts away from the affected lung.
CONTRACTION ATELECTASIS
This is seen when there is local or generalized fibrotic changes in the lung or pleura to prevent full expansion
— Atelectasis is a reversible disorder except in contraction Atelectasis
PULMONARY EDEMA
—Pulmonary edema is fluid accumulation in the lung parenchyma.
The etiology could be either:
1.Hemodynamic disorder.
2.Microvascular injury.
-Thus classification is based on etiologic agent.
ETIOLOGY OF PULMONARY EDEMA
A.HEMODYNAMIC EDEMA
1. Increased hydrostatic pressure (increased pulmonary venous pressure) Seen in
-Left-sided heart failure (common)
-Volume overload
-Pulmonary vein obstruction
- Decreased oncotic pressure (less common)
-Hypoalbuminemia
-Nephrotic syndrome
-Liver disease
-Protein-losing enteropathies
3.Lymphatic obstruction (rare)
B.EDEMA DUE TO MICROVASCULAR INJURY (ALVEOLAR INJURY)
1.Infections: pneumonia, septicemia
2. Inhaled gases: oxygen, smoke
3.Liquid aspiration: gastric contents, near-drowning
4.Drugs and chemicals: chemotherapeutic agents (bleomycin), other medications (amphotericin B), heroin, kerosene, paraquat
5.Shock, trauma
6.Radiation
7.Transfusion related
C.EDEMA OF UNDETERMINED ORIGIN
-High altitude
-Neurogenic (central nervous system trauma)
HEMODYNAMIC DISORDER
The commonest hemodynamic cause of pulmonary edema is (increased hydrostatic pressure), as seen in left-sided congestive heart failure.
GROSSLY: clinically there is pulmonary congestion and edema as evident by:
A. heavy lungs.
B. wet lungs.
—Dependent edema is seen in the basal regions of the lower lobes due to increase hydrostatic in these sites .
HISTOLOGICALLY:
1.Engorgement of alveolar capillaries
2. Granular Pink precipitate in intra alveolar space
3. Alveolar microhemorrhages
4. Heart failure cells may be present(hemosiderin-laden macrophages)
5. In long standing cases such as mitral stenosis, Hemosiderin-laden macrophages are abundant, fibrosis and thickened alveolar wall too.
MICROVASCULAR INJURY
Edema is as a result of
1. Primary injury to vascular endothelium
2. Damage to alveolar epithelial cells
-resulting in fluids and protein leakage into the interstitial space initially
And to the alveoli in severe cases.
ACUTE LUNG INJURY (ALI) / ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS)
INTRODUCTION:
—Both ALI/ARDS are pulmonary inflammatory associated disorder with epithelial and endothelial cell injury.
DEFINITIONS:
1. Acute lung injury (ALI) (noncardiogenic pulmonary edema) -Is a disease characterized by the abrupt onset of significant Hypoxemia and Diffuse pulmonary infiltrates in the absence of cardiac failure.
- Acute respiratory distress syndrome (ARDS): This refers to severe ALI.
3.Acute interstitial pneumonia: ALI in the absence of any etiology.
- Diffuse alveolar damage : Is the histologic manifestation of ALI.
