Atelectasis, ARDS, Pulmonary edema

Question 1

In relation to Neonates, what is Atelectasis ?

Answer 1

Neonatal Atelectasis an incomplete explanation of the lungs

Question 2

Acquired Atelectasis is defined as?

Answer 2

A collapse of previously inflated lungs, resulting in areas of relatively airless pulmonary parenchyma.

Question 3

Acquired atelectasis occurs commonly in ?

Answer 3

Adults

Question 4

List the different types of acquired atelectasis ?

Answer 4

• Resorption or obstruction Atelectasis
• Compression Atelectasis
• Contraction Atelectasis

Question 5

In 6 steps, what’s occurs in resorption atelectasis?

Answer 5

• This occurs from complete obstruction of an airway
• Overtime, Air (oxygen) trapped in dependent alveoli (distal alveoli) is resorbed.
• resorption occurs without impairment of blood flow through the affected alveoli walls
• Because the lung volume is diminished, the mediastinum shifts TOWARDS the atelectatic lungs

Question 6

Causes of resorption atelectasis

Answer 6

1. Excessive secretions (Mucus plugs)
2. Exudates within smaller bronchi. This is seen in conditions like?
   - Bronchial Asthma
   - Chronic Bronchitis
   - Bronchiectasis
   - Postoperative states
   - Foreign body aspiration
   - Bronchial neoplasms (intrabrochiaL-tumors)

Question 7

Compression atelectasis ?

Answer 7

This results from the accumulation of a significant volume of
- Fluid( exudate, Transudafe)
- Air (Pneumothorax, Tension pneumothorax)
- Blood
- Tumor
Accumulate in the pleural cavity

Mediastinum shifts away from the affected lung

Question 8

Contraction atelectasis ?

Answer 8

• This occurs when focal or generalized pulmonary or pleural fibrosis prevent full lung expansion

Question 9

Atelectasis is a reversible disorder except in?

Answer 9

Contraction Atelectasis

Question 10

Significant atelectasis complications?

Answer 10

• Leads to reduced oxygenation
• Predisposes to infection

Question 11

Pulmonary edema Definition?

Answer 11

Pulmonary Edema is defined as an abnormal increase in the interstitial fluid within lung parenchyma

Question 12

Etiology of pulmonary Edema can be classified into?

Answer 12

• hemodynamic disorders
• Microvascular injury

Question 13

Hemodynamic pulmonary edema is further classified into?

Answer 13

1) increased hydrostatic pressure - increased pulmonary Venous pressure
2) Decreased oncotic pressure
3) lymphatic obstruction (rare)

Question 14

Causes of increased hydrostatic pressure includes?

Answer 14

• Left sided heart failure
• volume overload
• pulmonary vein obstruction

Question 15

Causes of decreased oncotic pressure ?

Answer 15

• Hypoalbuminemia
• nephrotic syndrome
• liver diease
• protein losing Enteropathies (PLE)

Question 16

Classification of edema due to microvascular injury (alveolar injury)

Answer 16

Primary injury to the vascular endothelium
- infection; pneumonia, septicemia
- inhaled gases; oxygen, smoke
- liquid aspiration; gastric contents, near drowning
- Radiation
- Lung trauma
Indirect injury
- systemic inflammatory response syndrome (Sepsis, extensive trauma, burns, pancreatitis)
- Blood transfusion related
- Drugs and chemicals; chemotherapeutic agents (bleomycin), amphotericin B, heroine, cocaine, Paraquat, kerosine

Question 17

What can cause Edema of undetermined origin?

Answer 17

• Neurogenic edema- CNS trauma
• High altitude

Question 18

The commonest hemodynamic cause of pulmonary edema is ?

Answer 18

Increased hydrostatic pressure (as seen in left-sided heart failure )

Question 19

Gross description of pulmonary edema

Answer 19

Clinically there’s pulmonary congestion and edema is evident by
- wet lungs
- Heavy lungs

Question 20

What’s dependent edema ?

Answer 20

Edema accumulates initially in the basal regions of the lower lobes because hydrostatic pressure is greatest in these sites.

Question 21

Histological features of pulmonary edema?

Answer 21

1. Engorgement of the alveolar capillaries
2. The presence of finely granular pale pink precipitate in the intra-alveolar space
3. Presence of alveolar microhemorrhages
4. Presence of hemosiderin-laiden macrophages (heart failure cells)

Question 22

Histological features of long standing pulmonary congestion ?

Answer 22

As seen in mitral stenosis
1) Abundant hemosiderin-Laiden macrophages
2) fibrosis and thickening of the alveoli walls
3) soggy lungs become firm with brown induration

Question 23

Edema in microvascular injury occurs as a result of?

Answer 23

1) Primary injury to vascular endothelium
2) Damage to alveolar epithelial cells
- Results in fluids and protein leakage into the interstitial space and then into the alveoli

Question 24

Injury-related alveolar edema is an important feature of which condition ?

Answer 24

Acute respiratory distress syndrome (ARDS)

Question 25

What’s the underlying pathology in **Acute lung injury** and **ARDS**

Answer 25

Pulmonary inflammation with **epithelial** and **endothelial cell injury**

Question 26

Definition of Acute Lung injury ?

Answer 26

Characterized by an **abrupt onset** of significant **hypoxemia** and **diffuse pulmonary infiltrates** in the **absence of cardiac failure** Bilateral pulmonary edema (non-Cardiogenic pulmonary edema)

Question 27

ARDS is defined as?

Answer 27

This is a manifestation of **severe Acute lung injury**.

Question 28

Histological manifestation of ALI and ADRS?

Answer 28

Diffuse alveolar Damage

Question 29

**Acute interstitial pneumonia** is defined as ?

Answer 29

Acute lung injury occurring in the **absence of any trigger, or any etiology**

Question 30

Etiology of ALI?

Answer 30

Complication from **direct lung injuries** or **systemic disorder** 1) Infections; 2) Physical injury 3) inhaled irritants 4) chemical injury 5) hematological conditions 6) uremia 7) pancreatitis 8) hypersensitivity reactions (organic solvents and drugs)

Question 31

Examples of infections cause ALI?

Answer 31

- sepsis - Diffuse pulmonary infection - viral infection - mycoplasma - Pneumocystis pneumonia - Miliary tuberculosis - Gastric aspiration

Question 32

Examples of physical injury causing ALI?

Answer 32

- Head injuries - Pulmonary contusions - Near drowning - Fractures with fat embolism - Burns - Ionizing radiation

Question 33

Examples of inhaled irritants causing ALI?

Answer 33

- Oxygen toxicity - Smoke - Irritant gases and chemicals

Question 34

Examples of chemical injury causing ALI?

Answer 34

- Heroin or methadone overdose - Acetyl salicylic acid - Barbiturate overdose - Paraquat

Question 35

examples of Hematological conditions that can cause secretion

Answer 35

- Multiple transfusions - Disseminated intravascular coagulation

Question 36

In the pathogenesis of ARDS, what’s is the root cause (pathogenesis )

Answer 36

An imbalance between **pro-inflammatory** and **anti-inflammatory conditions**

Question 37

Following an acute lung injury? What happens in ADRS?

Answer 37

- Macrophages activate and increase synthesis of IL8, IL1 and TNF **IL8** - is a potent neutrophil chemotactic.

Question 38

Functions of IL8 and TNF ?

Answer 38

- IL8 causes activation of neutrophils - TNF aids **activated neutrophils to bind their ligands on activated endothelial cells** by up-regulating the expression of adhesion molecules

Question 39

Stiff neutrophils that are trapped in lung capillary bed secret what?

Answer 39

Inflammatory substances like - protease - Oxidants - platelet activating factors - leukotrienes

Question 40

Loss of surfactant causes ?

Answer 40

Endothelial and epithelial injury leads to **loss of surfactant** and **inability of the alveoli unit to expand**

Question 41

Dysregulation of coagulation system in ARDS ?

Answer 41

Yes, - the **protein C** and **anticoagulant levels** are **decreased** in plasma and Bronchoalveloar lavage fluid - **Tissue factor** levels are **increased**

Question 42

Clinical features of ARDS?

Answer 42

- Increasing Cyanosis - Increasing Hypoxemia - Profound Dyspenea - Profound tachypnea - Respiratory acidosis - Respiratory failure

Question 43

Gross description of ALI in acute phase?

Answer 43

Lungs may be - Heavy - Red - Boggy - Firm

Question 44

Histological features of ARDS/ ALI?

Answer 44

- interstitial and intra-alveolar **edema** - congestion - **fibrin deposition** - **Diffuse alveolar damage** - alveolar walls become lined with **waxy hyaline membranes**

Question 45

Chronic histological features of ARDS/ALI

Answer 45

- **Proliferation of type 2 pneumocytes** - **Granulation tissue** seen in the alveolar spaces - **Fibrotic thickening of the alveolar septa and walls** due to interstitial cells proliferation and collagen deposit

Question 46

Summarized pathogens is of ALI, ARDS

Answer 46

- Endothelial activation - Adhesion and extravasation of neutrophils. - Accumulation of intra-alveolar fluid and formation of hyaline membranes - Resolution of injury **Damage to endothelial and alveolar epithelial cells and secondary inflammation** are the key initiating events and the basis of lung damage.

Question 47

Radiological findings in ARDS?

Answer 47

Diffuse bilateral Lung infiltrate

Question 48

Treatment of ARDS

Answer 48

- Treat the underlying cause - sepsi etc - Mechanical ventilation - Supportive care

Question 49

Investigations to be carried out for this patient?

Answer 49

Sepsis work up FBC E/U/Cr

Question 50

Complications of ARDS?

Answer 50

- Bronchopneumonia - Sepsis - Multi organ failure - Diffuse alveolar damage