Diffuse Interstitial Lung Diseases

A diverse group of lung disorders that produce similar inflammatory and fibrotic changes in the interstitium or interalveolar septa of the lung

Types of Diffuse Interstitial Lung Diseases

Sarcoidosis
The occupational lung diseases (asbestosis, pneumoconiosis, silicosis, pneumonitis, etc.)
Hypersensitivity pneumonitis
Lung diseases caused by exposure to toxic drugs

Sarcoidosis

A disease of unknown origin characterized by the formation of granulomatous lesions that appear especially in the lungs, liver, skin, and lymph nodes.
Etiology is probably immune or autoimmune
Malaise, fever, dyspnea, dry cough

Pneumoconioses

Occupational" or "dust" diseases
Black lung (coal)
Silicosis (silicon)
Asbestosis
Inert particles are walled off by immune cells that lay down fibrin
Fibrosis�stiff lung
Barrier to diffusion

Causes of Disorders of Lung Inflation

Conditions that produce lung compression or lung collapse
Collapse of a segment of the lung as in atelectasis
Compression of the lung by an accumulation of fluid in the intrapleural space
Complete collapse of an entire lung as in pneumothorax

Atelectasis

The incomplete expansion of a lung or portion of a lung
Causes
Airway obstruction
Lung compression such as occurs in pneumothorax or pleural effusion
Increased recoil of the lung due to loss of pulmonary surfactant

Pleural Effusion

An abnormal collection of fluid in the pleural cavity
Types of fluid
Serous, purulent (empyema), blood, etc.
S&S
Dyspnea
Pleuritic pain
Dry cough
Decreased breath sounds

Characteristics of Pleural Pain

Unilateral, localized to lower and lateral part of the chest
May be referred to the shoulder
Usually made worse by chest movements
Tidal volumes are kept small
Breathing becomes more rapid
Reflex splinting of the chest may occur

Diagnosis and Treatment of Pleural Effusion

Diagnosis
Chest radiographs, Chest ultrasound
Computed tomography (CT)
Treatment: Directed at the cause of the disorder
Thoracentesis
Injection of a sclerosing agent into the pleural cavity
Open surgical drainage

Pneumothorax

A collection of air or gas in the pleural space of the lung, causing the lung to collapse.
S&S
Dyspnea
Chest pain on affected side
Tachycardia
Decreased or absent breath sounds
Tracheal shift if severe

Spontaneous pneumothorax

Occurs when an air-filled blister on the lung surface ruptures

Traumatic pneumothorax

Caused by penetrating or non-penetrating injuries

Tension pneumothorax

Occurs when the intrapleural pressure exceeds atmospheric pressure

Pulmonary Hypertension

Pulmonary arterial pressure > 30mmHg
(normal 25/8)

Primary pulmonary hypertension

Usually in women aged 30 - 40
Rapidly progressive
Poor long-term prognosis

Causes of Secondary Pulmonary Hypertension

Increased pulmonary vascular resistance
Vasoconstriction
Obstruction
Destruction
Increased left atrial pressure
Increased pulmonary blood flow
Increased blood viscosity

S & S of Secondary Pulmonary Hypertension

Dyspnea and fatigue
Peripheral edema
Ascites
Signs of right heart failure (cor pulmonale)

Pulmonary Embolism

A blood-borne substance lodges in a branch of the pulmonary artery and obstructs the flow
Types
Thrombus: venous blood clot
Fat: mobilized from the bone marrow after a fracture
Amniotic fluid: enters the maternal circulation after rupture of the membranes

Pulmonary Edema

Accumulation of fluid in the interstitium and alveoli of the lungs
Most commonly caused by left heart failure
Fluid in alveoli causes
Lung stiffness
Difficult expansion
Impaired gas exchange

Pulmonary Edema S & S

Severe dyspnea and air hunger
Cough productive of frothy, blood tinged sputum
Tachypnea and tachycardia
Cold, clammy skin
Cyanosis
Extreme apprehension
Confusion, stupor

Acute Respiratory Distress Syndrome

Disorder caused by disseminated pulmonary inflammation
Leads to profound hypoxemia and increased work of breathing

Causes of ARDS

Shock
Major trauma (with or without fat emboli)
Sepsis secondary to pulmonary or non- pulmonary infections
Acute pancreatitis
Hematologic disorders
Aspiration
Reactions to drugs and toxins
Inhalation of toxins

Pathology of ARDS

Diffuse epithelial cell injury
Increased permeability of alveolar- capillary membrane
Fluid collects in inerstitium and alveoli
Surfactant inactivation
Hyaline membrane formation
Increased work of breathing
Intrapulmonary shunting of blood
Impaired gas ex

Manifestations of ARDS

Profound hypoxia
Tachypnia
Severe dyspnea
Hypotension
Hypercapnia
Acidosis
Multiple organ failure
Mortality: 30 - 60%

Acute Respiratory Failure

State of disturbed gas exchange
Defined as
PaO2 < 60 mmHg
PaCO2 > 50 mmHg
May involve
Hypoxemia
Hypercapnia
Both

Acute Respiratory Failure Causes

Causes
Emphysema, pneumonia, asthma, CNS disorders, shock, neuromuscular disorders, trauma, and many others

Acute Respiratory Failure Manifestations

Confusion, decreased LOC
Tachypnea, tachycardia
Tremors
Hypotension
Cyanosis, retractions, dysrhythmias, cool/clammy skin