ARDS/Pulm effusion

Question 1

Acute Respiratory Distress Syndrome (ARDS)

general

Answer 1

Life-threatening diffuse inflammatory form of lung injury

Characterized by bilateral lung infiltrates and progressive hypoxemia without cardiac failure

The underlying mechanism of ARDS is capillary endothelial injury and diffuse alveolar damage (DAD)

Epidemiology:
Most common cause of non-cardiogenic pulmonary edema
~190,000 cases of ARDS in the United States each year
~22% of patients who are mechanically ventilated meet the criteria for ARDS
Mortality rate: 9-20%

(you give supplemental O2 and they stay hypozic and desat) (can;t be related to cardio

Question 2

ARDS

Etiology

Direct lung injury

Answer 2

Results from clinical disorders that affect the lungs either directly or indirectly
Direct lung injury:
Bacterial and viral pneumonia
Aspiration of gastric contents
Pulmonary contusion
Near-drowning incidents
Toxic inhalation injury
Lung transplant

Question 3

ARDS

Etiology

Indirect lung injury

Answer 3

Indirect lung injury:
Sepsis (most common cause)
Severe trauma with prolonged hypovolemic shock
Drug overdoses
Bone marrow transplantation
Post-cardiopulmonary bypass
Massive blood transfusion
Pancreatitis
Fat or amniotic fluid embolism

Question 4

Question 5

ARDS

Patho - 1

EXUDATIVE

(the worst phase)

Answer 5

Occurs in 3 phases – exudative, proliferative, fibrotic

Exudative: 6-72 hours after the eliciting factor

Initial injury (cytokines) causing damage to pneumocytes and pulmonary endothelium → disrupted barriers between capillaries and airspaces (leaky)

Inflammatory reaction is initiated with endothelial cells secreting pro-inflammatory molecules and expressing adhesion molecules on their surface

Immune cells (neutrophils – 1st to arrive) stick and then migrate into the alveoli → neutrophils will release proteases and reactive oxygen molecules, and more cytokines to perpetuate the cycle

Edema fluid, protein, and cellular debris flood the airspaces

Disruption of surfactant → ↑ surface tension → airspace collapse, ventilation-perfusion mismatch, right-to-left shunting of venous blood leading to pulmonary hypertension

Question 6

ARDS

what kind of shunting do we see?

Answer 6

Right to left.
deoxygenated blood getting back into circulation leading to hypoxia

Question 7

ARDS

Patho - 2

Proliferative

Answer 7

Beginning stages of lung repair

Alveolar epithelial cells begin proliferating along the alveolar basement membranes

Macrophages clean up cellular debris and attract and activate fibroblasts

New pulmonary surfactant is produced

Question 8

ARDS

Patho - 3

Fibrotic

Answer 8

Abnormal deposition of collagen in the alveolar ducts and interstitial membranes by fibroblasts

Lung scarring; “stiff” lungs → restrictive lung disease

Stiff lungs – poor lung compliance, reduced diffuse capacity, microvascular occlusion

Question 9

Question 10

Question 11

ARDS

Expected vitals

Answer 11

Mild dyspnea → respiratory distress/failure

Vitals
Tachypnea
Tachycardia
Fever may/may not be present
Hypoxemia despite supplemental oxygen

Question 12

ARDS

PE findings

Answer 12

Physical exam
Diffuse crackles (rales)
Worse at the bases
Labored breathing
Retractions
Restlessness and/or anxious
Cyanosis
Altered level of consciousness

Exam findingsNOTconsistent with ARDS: new or changed murmur, S3 or S4 gallop, jugular venous distension (JVD), lower extremity pitting edema

Question 13

ARDS

Dx (4)

Answer 13

Berlin diagnostic criteria of ARDS:

1. Acute onset (within 1 week)
2. Diffuse bilateral infiltrates on chest x-ray or CT scan
3. No evidence of heart failure or fluid overload
4. Partial pressure of O2/fraction of inspired O2(PaO2/FiO2) < 300 mmHg:
   Mild ARDS:201–300 mm Hg
   Moderate ARDS: 101–200 mm Hg
   Severe ARDS: ≤ 100 mm Hg

if you have JVD, pulm edema, cardiomegaly,pedal edema its HF not ARDS

Question 14

Answer 14

CXR Day 1
70-year-old female admitted with acute respiratory failure, fever (38ºC) and dyspnea. She was tachypneic (30 bpm), with lymphopenia and low oxygen saturation (SpO2 85%, PAFI<250). Covid-19 positive.

she died on day 4

Question 15

ARDS

CXray

Answer 15

Chest X-ray:
ARDS: bilateral pulmonary infiltrates
Finding more consistent with bacterial pneumonia: consolidation

Findings more consistent with cardiogenic pulmonary edema:
Pulmonary venous congestion
Cardiomegaly
Pleural effusion

Question 16

ARDS

Question 17

ARDS

Labs

Answer 17

Labs
BNP levels < 100 pg/mL favors ARDS

Arterial blood gas (ABG):
Hypoxemia

Additional testing to determine the underlying cause (example: lipase for possible pancreatitis)

Question 18

ARDS

Tx

Answer 18

Patients are managed in the ICU
Correct the underlying cause

Supplemental oxygen:
Most patients require a high FiO2 (> 50%)
Delivered via high-flow nasal cannula, nonrebreather face mask, or by intubation (mechanical ventilation)
Failure of oxygen saturation improvement > 90% - suspect right-to-left shunting of blood

Mechanical ventilation:
If oxygen saturation is < 90% on high-flow oxygen
High PEEP
Low tidal volume (6 mL/mg)– most critical factor in reducing mortality rates
Prone positioning improves oxygenation
Fluid management is difficult
Large volume to maintain blood pressure
Fluid restriction to reduce left atrial filling pressure and improve oxygenation
Diuretics can facilitate fluid restriction/removal

Patients will require high PEEP (positive-end expiratory pressure) to keep the alveoli from collapsing

Question 19

ARDS

Prognosis and RF

Answer 19

Serious condition that is usually associated with high mortality and morbidity

Risk factors forestimating the prognosis in a patient with ARDS:
Advanced age
Direct lung injuries result in twice the number of mortalities
Preexisting organ dysfunction from chronic diseases:
Chronic liver disease
CKD
Immunosuppression

The majority ofpatientsrecover most of their lung function over several months

Question 20

Question 21

PE

Pleural Fluid

Answer 21

Forces (hydrostatic and osmotic pressures) responsible for producing pleural fluid within the capillary bed of theparietal pleura
Pleural fluid is absorbed bylymphvessels in the diaphragmatic and mediastinal surfaces of theparietal pleura; ultimately drains into the right atrium
The normal mean rate of production andabsorptionof the pleural fluid is 0.2 mL/kg/hour
The entire volume of pleural fluid normally turns over within 1 hour

Question 22

How does pleural effusion form?

Answer 22

Formation of a pleural effusion results from:
Overproduction of pleural fluid OR
Inability of the lymphatic system to remove fluid as it is produced

Question 23

Answer 23

Question 24

Pleural Effusion

general
Exudative vs transudative

Answer 24

Excessive accumulation of fluid within the pleural cavity (between the parietal and visceral pleura)

Classified as exudative or transudative based on Light’s criteria
Exudative
Caused by inflammation and ↑ capillary permeability
Fluid rich in protein and LDH in the pleural space

Transudative
Caused by a combination of ↑ hydrostatic pressure in the vasculature and ↓ oncotic pressure in the plasma

Question 25

# P effusion etiology | transudate vs exudate

Answer 25

Transudate: Examples: **Heart failure (HF)**- 90% of cases Liver cirrhosis Hypoalbuminemia Nephrotic syndrome Exudate: Examples: **Pneumonia** Empyema Tuberculosis (TB) Malignancy (most commonly a primary lung cancer) Connective tissue diseases Pancreatitis Asbestos Post-cardiac injury syndrome

Question 26

# pulm effusion Pulm embolism

Answer 26

THis is the only cause that will give you both transudative **and** exudative Pulmonary embolism Transudative effusion Obstruction of the pulmonary circulation → ↑ hydrostatic pressure Exudative effusion Release of vasoactive mediators from platelet-rich clots → ↑ capillary permeability

Question 27

# pulm effusion Symptoms

Answer 27

May be asymptomatic Symptoms Dyspnea (most common) Pleuritic chest pain Indication of pleural inflammation **Worsens with deep inspiration or cough** Fever Cough- can have wityh both types.

Question 28

# Pulm effusion PE Findings | inspection palpation and percussion

Answer 28

Inspection: An **asymmetrical chest expansion** (reduced expansion on the side of the effusion) *Fullness of intercostal spaces*(can't see until its big) Palpation: **↓ or absent tactile fremitus** *Tracheal deviation* Trachea is shifted to the opposite side of the effusion Percussion: Effusion >300 mL, chest examination will also be notable for **dullness to percussion** The upper border dullness follows a laterally ascending curve apexing at the midaxillary line (Ellis–Damoiseau line) | fremitus increases with consolidation/pneumonia

Question 29

# Pulm effusion PE findings | auscultation

Answer 29

Auscultation: **↓ or inaudible breath sounds over the effusion**  Bronchial breath sounds, bronchophony, and egophony: Heard over the lung parts directly above the effusion Pleural friction rub synchronous with respiration

Question 30

# Pulm effusion Determining the Etiology

Answer 30

Look for associated symptoms and physical examination findings that may clue you in: Fever, chills, productive cough → pneumonia Unintentional weight loss, early satiety, loss of appetite, constant chest pain → malignancy Night sweats, hemoptysis, and travel to endemic area → tuberculosis Weight gain, orthopnea, peripheral edema, jugular venous distention → congestive heart failure Occupational exposure to asbestos → mesothelioma Joint pain with or without effusion and/or skin rash → connective tissue disease “If you are effusing in TWO, think AUTOIMMUNE”

Question 31

# Pulm effusion CXray

Answer 31

Chest x-ray **Best initial test** to determine the presence of an effusion Minimum of 200 mL of fluid to obliterate the costophrenic angle Findings Abnormal blunting of costophrenic angles Fluid within horizontal or oblique fissures Effusions may demonstrate a meniscus Massive effusions Complete opacification of a hemithorax Tracheal deviation away from the affected side Mediastinal shift

Question 32

Answer 32

PA CXR showing bilateral pleural effusions: Blunting of the costophrenic angle (particularly on the right) Meniscus on the left MOST of the time bilat effusion is CHF but take Hx into account could be other things. | Pulm effusion

Question 33

# Pulm effusion Lateral decubitus films

Answer 33

Lateral decubitus films **Most sensitive** Can detect effusions with a minimum of **50 mL** Look at the distance between the chest wall and top of the fluid level Diagnostic thoracentesis should be performed on all patients that have pleural fluid ≥ 10 mm (1 cm) of thickness on imaging and that is new or of uncertain etiology **Determine if the effusion is: Fluid layering (free-flowing) → transudative effusion Loculated → exudative effusion**

Question 34

# Pulm effusion Pleural Fluid Analysis

Answer 34

Sample of pleural fluid by performing a diagnostic thoracentesis Pleural fluid should be sent for: Cultures and microscopy Bacteria Acid-fast bacilli Fungi Cytology  Cell count with differential pH Lactate dehydrogenase (LDH) Total protein Albumin Glucose Additional investigations include (based on clinical suspicion): Amylase → pancreatitis, esophageal rupture Triglycerides → chylothorax Rheumatoid factor and antinuclear antibodies → autoimmune disorders Acid-fast bacilli smear and adenosine deaminase (ADA) → TB

Question 35

# Pleural effusion Lights criteria

Answer 35

**Exudative** pleural effusion with any one of the following characteristics: Pleural fluid protein/serum protein ratio > 0.5 Pleural fluid LDH/serum LDH ratio > 0.6 Pleural fluid LDH > 2/3 of the upper limit of normal for serum **Transudative** pleural effusions meet none of the above characteristics

Question 36

# Pulm effusion Tx

Answer 36

Initial management for symptomatic patients Assess airway, breathing, and circulation Provide supplemental oxygen **Urgent drainage if:** Severe respiratory distress or respiratory failure Evidence of obstructive shock Interventions Therapeutic thoracentesis 1-1.5 L per treatment Chest tube placement (tube thoracostomy) Indwelling pleural catheter Management of symptoms and the underlying cause NSAIDs or other analgesics for pleuritic pain

Question 37

# pulm effusion Complications(4)

Answer 37

Question 38

# pulm effusion Thoracentesis

Answer 38

Performed using ultrasound to allow for visualization of anatomical structures Needle is inserted **above the rib** to avoid damage to the intercostal vein, artery, and nerve Procedural risks: Pneumothorax Vascular injury → hemothorax Re-expansion pulmonary edema

Question 39

# Special Forms of Pleural Effusion Parapneumonic effusion (effusion around an infection) Uncomplicated vs complicated

Answer 39

Parapneumonic effusion (effusion around an infection) Exudative, neutrophilic pleural fluid associated with pneumonia Classification: Uncomplicated No bacterial invasion of the pleura Will resolve with management of the pneumonia Complicated Bacterial invasion of the pleura Bacteria are rapidly cleared from the pleural space → cultures are usually negative

Question 40

# parapleural effusion Empyema

Answer 40

**Empyema** Bacterial infection of the pleura Pleural fluid will be thick, viscous, and opaque (**pus**) Require surgical drainage with a thoracostomy or chest tube PLUS antibiotics

Question 41

# pulm effusion

Question 42

# special pulm effusion Chylothorax

Answer 42

Chylothorax Lymphatic fluid in the pleural cavity due to impaired drainage Etiology: Trauma Surgery Malignancy Congenital anomalies Pleural fluid Cloudy and milky-appearing fluid Exudate High concentration of triglycerides and chylomicrons Lymphocytic predominance

Question 43

# special pulm effusions Hemothorax

Answer 43

Hemothorax Accumulation of blood in the pleural cavity Etiology: Trauma Malignancy Coagulopathy Connective tissue disease Pleural fluid: Frank blood (pleural fluid hematocrit > 50% peripheral hematocrit) Exudate

Question 44

# pulm effusion when is thoracentesis not required?

Answer 44

Thoracentesis not required: Heart failure with symmetric pleural effusions and no chest pain or fever Diuresis can be tried, and thoracentesis avoided unless effusions persist for ≥ 3 days