Pulmonary Edema - Patho 2 (not done?)

What does this refer to

• Primary gas-exchange units

• Pores of Kohn

  • Permit air to pass through the septa from alveolus to alveolus

    • Collateral ventilation and even air distribution

• Lungs contain approximately 25 million ____ at birth and 300 million by adulthood

Alveoli

What does this refer to

• Formed by shared alveolar and capillary walls

• Thin membrane of alveolar epithelium, the alveolar basement membrane, interstitial space, the capillary basement membrane, and the capillary endothelium

Alveolocapillary membrane (Pulmonary and Bronchial Circulation)

What does this refer to

Blood-gas barrier

What does this refer to

• Adequate inspired O2 – (FiO2)

• Ventilation and perfusion of alveoli

• A permeable alveolocapillary membrane

• Adequate blood flow

• Ability to transport O2 and CO2

• Ability of cell to use O2 and eliminate CO2

Requirements for Ventilation, Perfusion, and Diffusion

What does this refer to

• Tendency of water molecules to contract to the smallest possible surface area (bead) with exposure to air

• Increased ______= increased work of breathing

Surface Tension of Water

What does this refer to

• The smaller a sphere’s radius (alveoli) the greater the surface tension and the more difficult (work) to expand the alveoli

• Surfactant reduces fluid surface tension lining the alveoli and decreases tendency to collapse, preventing atelectasis

Laplace’s Law

What does this refer to

• Four steps

  • Ventilation of the lungs

  • Diffusion of oxygen from the alveoli into the capillary blood

  • Perfusion of systemic capillaries with oxygenated blood

  • Diffusion of oxygen from systemic capillaries into the cells

• Diffusion of CO2 occurs in reverse order

Gas Transport

What does this refer to

• Accumulation of fluid in lung interstitium and alveoli

• Impaired gas exchange → hypoxia

• Common cause of respiratory distress

Pulmonary Edema

What does this refer to

• Maintained by Starling forces

• Low pulmonary capillary hydrostatic pressure

• Effective lymphatic drainage

Normal Pulmonary Fluid Balance

What does this refer to

• Fluid movement = Kf [(Pc - Pi) - σ(πc - πi)]

  • Kf = filtration coefficient

  • Pc = capillary hydrostatic pressure

  • πc = capillary oncotic pressure

Starling Equation

What does this refer to

1. Increased hydrostatic pressure

2. Decreased oncotic pressure

3. Increased capillary permeability

4. Lymphatic obstruction

Mechanisms of Pulmonary Edema

What does this refer to

• Drain excess fluid from interstitium

• Obstruction or overload can exacerbate edema

• Chronic edema may impair lymphatic clearance

Lymphatic Role in Pulmonary Edema

What does this refer to

• Fluid in alveoli blocks oxygen diffusion

• V/Q mismatch and shunt physiology

• Hypoxia and dyspnea result

Gas Exchange Impairment

What does this refer to

Ventilation-Perfusion

What does this refer to

• Dyspnea, orthopnea, crackles on auscultation

• Pink frothy sputum (severe cases)** know this

• Tachypnea, hypoxia, cyanosis

Clinical Features of Pulmonary Edema

What does this refer to

• Cardiogenic: Kerley B lines, perihilar infiltrates, cardiomegaly

• Non-cardiogenic: bilateral infiltrates, normal heart size

• CT may show ground-glass opacities

Radiologic Findings

What does this refer to

• Due to elevated left atrial pressure

• Common causes: LV failure, mitral stenosis

• ↑ Pulmonary capillary hydrostatic pressure

Cardiogenic Pulmonary Edema

What does this refer to

• Backward transmission of pressure

• Fluid leaks into interstitium → alveoli

• Often seen in congestive heart failure

Hemodynamic Changes in Cardiogenic Edema

What does this refer to

• Normal cardiac pressures

• Caused by increased capillary permeability

• Etiologies: ARDS, sepsis, aspiration, trauma

Non-Cardiogenic Pulmonary Edema

What does this refer to

• Endothelial damage → protein-rich fluid

• Inflammatory cytokines: TNF-α, IL-1

• Seen in ARDS and infections

Capillary Leak Syndrome

What does this refer to

• Severe form of non-cardiogenic edema

• Diffuse alveolar damage and inflammation

• Leads to hypoxemia and stiff lungs

Acute Respiratory Distress Syndrome (ARDS)

What does this refer to

• Non-cardiogenic: triggered by hypoxia

• Vasoconstriction → elevated pulmonary pressures

• Capillary stress failure and leakage

High Altitude Pulmonary Edema (HAPE)

What does this refer to

• Occurs after CNS insult (e.g., head trauma)

• Sympathetic surge causes vasoconstriction

• ↑ Hydrostatic pressure in pulmonary circulation

Neurogenic Pulmonary Edema

What does this refer to

• Fluid overload and hypoalbuminemia

• ↓ Oncotic pressure → fluid transudation

• Often mixed mechanism with cardiac involvement

Pulmonary Edema in Renal Failure

What does this refer to

• Pulmonary edema arises from various pathophysiological pathways

• Cardiogenic vs. non-cardiogenic classification aids management

• Understanding mechanisms is key to diagnosis and treatment

Summary

What does this refer to

ARDS Chest x-ray

What is black on a chest x-ray

air

What is dark gray on a chest x-ray

fat

What is light gray on a chest x-ray

soft tissue

What is white on a chest x-ray

metal

What is off-white on a chest x-ray

bone

What does this refer to

Densities

What does this refer to

• D – Details

• R – RIPE

• S – Soft tissues and bones

• A – Airways

• B – Breathing

• C – Circulation

• D – Diaphragm

• E - Extras

Chest x-ray system DRS-ABCDE

What does this refer to

• Is this my patient’s X-ray done today?

• Patient’s information.

• Type of film. PA, AP, lat, erect/supine, L/R

• Date and time of X-ray.

Details (system of chest-x-ray)

What does this refer to

• R – Rotation. Look at clavicles.

• I – Inspiration. 5-6 anterior ribs/8-10 posterior ribs in MCL

• P – Picture. All of lung fields included. Angulation.

• E – Exposure aka Penetration. Look at spinous processes, diaphragm.

RIPE (system of chest-x-ray)

What does this refer to

• Pneumothorax. Look at apices.

• Lung fields.

• Vascularity.

• Lesions, masses, air-fluid levels

• Pleura

Breathing (system of chest-x-ray)

What does this refer to

• Shoulders, clavicles, ribs, sternum, spine

• Soft tissue symmetry, swelling, subcutaneous air, masses

• Breasts

• Calcifications – especially in vessels

Soft tissues and bones (system of chest-x-ray)

What does this refer to

• Trachea midline

• Mediastinal masses

• Carina and main stem bronchi

• Aortic knob

• Hilum

• Vessels

Airways and mediastinum (system of chest-x-ray)

What does this refer to

• Heart position

• Heart size

• Heart borders

• Heart shape

• Aortic stripe

Circulation (system of chest-x-ray)

What does this refer to

• Diaphragm shape

• Hemidiaphragms

• Costophrenic angles

• Gastric bubble

• Pneumoperitoneum

Diaphragm (system of chest-x-ray)

What does this refer to

• Tubes and lines– ETT, NGT, central lines, chest tube, PICC lines

• Wires - Pacemaker, AICD, EKG electrodes

• Metal –bone fixators, bullets, buck shot, coins

Extras (system of chest-x-ray)