Interstitial Lung Disease

Known ethiology: dust, drugs, poisons, radiation, infectious agents, secondary to pulmonary edema and chronic uraemia.

Unknown ethiology: Sarcoidosis, amyloidosis

Pathophysiology

Regardless the cause, after the initial pulmonary paremchyma injury it occurs a accumulation of inflammatory and immune cells, that origin an alveolitis that can progress for the pulmonary acid destruction, pulmonary fibrosis and the cystic cavity formation. These events can origin capillary evolvement, pulmonary hypertension and finally right cardiac insufficiency (cor pulmonale).

Clinical manifestations

Dyspnoea

Pain

Discomfort

Hemoptysis (diffuse alveolar bleeding)

Quick and superficial breathing (due to a major resistance for lack of elasticity)

por perda de elasticidade)

Increased dead space

Increased work by the respiratory muscles

Respiratory insuffciency: Increased oxygen

CO2 pressure increased or normal

Idiopathic Pulmonary Fibrosis

Disease characterized by the cells infiltration in interstitial respiratory tissues (interstitial pulmonary disease) with healing of lung parenchyma. This leads to an increase in elastic recoil of the lung and a decrease of compliace, that we known as characteristics of restrictive pulmonary diseases.

Clinical presentation

Also known as criptogenic fibrosing alveolitis, the pulmonary fribosis is an uncommon disease that includes dry and persistent cough with no fever or chest pain. With the progress of the disease the dyspnea proliferates and originates cyanosis. In more advanced stages it occurs pulmonary hypertension that leads to peripheral edema and right cardiac insufficiency.

Phatophysiology

The primary injury that leads to fibrosis remains unknown. Meanwhile it can be observed a series of cellular events that regulates the inflammatory process and the fibrotic answer.

These events are:

- Initial injury of the tissue;

- Damage and vascular activation and trombolises in several degrees;

- Injury and epithelium activation with loss on the barrier integrity and release of proinflammatory mediators;

- Increased adhesion of leukocytes;

- Continuous process of injury and healing characterized by changes in cellular populations, and increased production of matrix with increased deposits of collagen and elastin.

These events lead to a pattern of pulmonary injury that causes an increased of the elastic recoil and changes on  gas exchange and pulmonary and vascular abnormalities.  

Clinical Manifestations

Cough

Dyspnea and tachypnea: It is necessary a larger effort to pulmonary distension. A fast and superficial inspiration pattern decreases the ventilation effort.  

Respiratory rales: Reflect the sucessive opening of respiratory units due to fibrosis and loss of surfactant.

Cardiatic Examination: hypoxemia, pulmonary hypertension, increased jugular venous pressure, tricuspid regurgitation murmur.

Pulmonary function tests: Reduction of CPT, FEV1 and FVC. DLCO progressively reduces.

Arterial blood gas analysis: Hypoxemia due to the increased dead space.

Pulmonary Edema

The pulmonary edema is the accumulation of excess fluid in the extravascular space of the lungs. This accumulation can slowly occur in patients with renal insufficiency or abruptly on patients with heart insufficiency to myocardial infarction. The pulmonary edema presents itself usually as dyspnea. In severe cases the pulmonary edema may present also edema liquid on the phlegm, leading to acute respiratory insufficiency.

Etiology

Causes of pulmonary edema:

Transmural increased pulmonary capilary wedge pressure (increased hydrostatic pressure): Increased left atrial pressure, pulmonary venous hypertension, increased capillary blood volume, decreased interstitial pressure, reduced colloid osmotic pressure (hypoalbuminemia due to nephrotic syndrome and liver failure).

Permeability of increased pulmonary capillary endothelium: Circulatin toxins, infectious pneumonia, pulmonary edema due to the high altitude after pulmonary bypass.

Increased permeability of the alveolar epithelium: Inhaled toxins, aspiration of gastric contents, drowning or near drowning, decreased surfactant.

Decreased lymphatic drainage.

Phatophysiology

A problem in one or more of the following factors: The capillary or alveolar endothelial permeability and the colloid osmotic and hydrostatic pressure are related to almost every clinic presentations of pulmonary edema.

In clinical practice these four factors are grouped into two types of pulmonary edema:

 - Cardiogenic pulmonary edema related to edema resulting from increased hydrostatic or osmotic pressure.

 - Noncardiogenic pulmonary edema  related to edema resulting from changes in the endothelium and alveolar capillary permeability. This edema it’s often known as Adult Respiratory Distress Syndrome (ARDS). The alveolar liquid that accumulates as result of lost of integrity of alveolar epithelium allows that solutes and large molecules (as albumin) entering the alveolar spaces. These changes can result from the injury of the alveolar epithelium by inhaled toxins or by pulmonary infection or even by changes that occur after a primary injury of the endothelium by circulating toxins. The circulating factors may act directly on capillary endothelium or may affect it by immune mediators. For example in infections by Gram bacteria the bacterial endotoxins cause the adherence of neutrophils and macrophages to endothelial surfaces that also cause the release of prostaglandins, thromboxanes and leukotrienes as oxygen radicals that cause oxidative injury. Both neutrophils and macrophages can release proteolytic enzymes that cause more damage.

Clinical manifestations

There are two types of pulmonary edema that cause an increase of the extravascular liquid in the lung and both can lead to respiratory insufficiency.