Pulmonary Diseases Flashcards
What are the classifications of pulmonary diseases?
Pulmonary diseases can be classified into 2 broad categories:
1. Restrictive vs. Obstructive
2. Infectious vs. Non-infectious
What are restrictive disorders and obstructive disorders?
- Restrictive disorders refer to the inability of the person to breathe in adequate amounts of air. These individuals have low lung volumes on pulmonary function tests (PFTs). Examples include aspiration, pulmonary fibrosis, atelectasis, bronchiolitis, and pulmonary edema.
- Obstructive disorders refer to the inability of the person to completely exhale air which has been inhaled. On PFTs these individuals will have high lung volumes because they are retaining air in the lungs. Disease examples include asthma and COPD.
What are the 2 main types of acute respiratory failure?
Hypoxemia and hypercapnic respiratory failure
What is hypoxemic respiratory failure defined by? Why?
Defined as a PaO2 of < 50mmHg. This is typically due to inadequate diffusion of oxygen from the alveoli to the capillary. Disorders that can impair diffusion are pulmonary edema, pulmonary embolus, and pneumonia.
What is hypercapnic respiratory failure defined by? What are cause of this?
Defined as a PaCO2 > 50mmHg. This is typically due to inadequate alveolar ventilation. Causes of hypercapnia include depression of the respiratory center by medications, abnormalities of the spinal cord systems, disorders of the medulla, diseases of the neuromuscular junction, chest wall abnormalities, or COPD.
What is a pneumothorax? What are the two types?
Presence of air or gas in the pleural space. The air in the thoracic cavity may press on the lung and cause it to collapse completely, or it may be a small amount of air that does not cause any difficulties. They two main types are spontaneous and secondary pneumothorax.
Who and how does spontaneous pneumothorax occur?
Occurs in young, tall, thin, males. They may also occur as a result of bleb rupture in persons who have emphysema. Smoking increases risk for spontaneous pneumothorax. In some individuals there is a genetic component and a family history of this diagnosis.
What is a bleb rupture?
Bleb ruptures are usually in the apexes and may occur during exercise, while at rest, or while asleep. The rupture allows air into the pleural space.
What is a secondary pneumothorax?
This is caused by trauma. A tension pneumothorax occurs when air becomes trapped in the thoracic cavity and can’t escape. The site of injury on the pleural membrane acts as a one-way valve and only lets air into the thoracic cavity. The person may then experience a complete lung collapse. This can then lead to deviated trachea, SOB, and hypotension.
What are clinical manifestations of a pneumothorax?
Sudden pleural pain, decreased breath sounds, and hyperresonance to percussion.
What is pulmonary edema?
Accumulation of water in the pulmonary alveolar sacs. This prevents the proper exchange of gases and leads to dyspnea, chest pain, and hypoxia. These individuals will also have orthopnea or paroxysmal nocturnal dyspnea.
What is pulmonary edema the most common cause of?
Pulmonary edema is the most common cause of left sided heart failure.
What happens to the lungs in left sided heart failure?
The backup of blood to the lungs increases capillary hydrostatic pressure which pushes fluid out into the alveolar sacs. ARDS or inhalation of toxic gases can cause capillary injury which leads to the movement of fluid into the alveolar space.
What is post obstructive pulmonary edema?
This occurs after relieving airway obstruction. Inspiration against an occluded airway creates excessive intrathoracic negative pressure which leads to increased venous return to the right side of the heart and a decreased outflow of blood from the left side of the heart. This creates increased pulmonary blood volume and pressure which causes the pulmonary edema.
What are clinical manifestations of pulmonary edema?
Dyspnea, hypoxemia, pulmonary rales, dullness to percussion, S3 heart sound, and frothy sputum.
What is Acute lung injury?
Type of respiratory failure which results from massive lung inflammation and disseminated alveolar capillary damage. This damage significantly impairs gas exchange, and the patient will have huge issues with oxygenation.
What is ARDS?
Acute respiratory distress syndrome is the most severe form of acute lung injury and is characterized by bilateral lung infiltrates seen on chest x-ray which are not explained by cardiac failure or fluid overload and a low ratio of partial pressure of oxygen to the fraction of inhaled oxygen.
What is the pathogenesis of ARDS?
- Inflammatory Phase: Occurs within the first 72 hours. The inflammatory cascade is triggered by an injury to the capillary membranes, which then increases the capillary permeability. Fluid, proteins, and blood cells then leak into the pulmonary interstitium and alveoli and impair gas exchange. Surfactant is inactivated and its production is impaired. The lungs lose compliance, work of breathing increases, alveolar ventilation decreases, and hypercapnia develops.
- Proliferative Phase: Pulmonary edema resolves, and surfactant is being produced again. This phase lasts 1-3 weeks. Intra alveolar exudate turns into a cellular granulation tissue and worsens the hypoxemia.
- Fibrotic Phase: Occurs between 14-21 days. There can be overlap between this phase and the proliferative phase. Here, the alveoli undergo fibrosis and ultimately this causes a decrease in pulmonary function which may be permanent. This leads to a decrease in functional residual capacity and a continuing V/Q mismatch with right to left shunting. The fibrosis causes pulmonary HTN.
What are clinical manifestations of ARDS?
hyperventilation, respiratory alkalosis, organ dysfunction, metabolic acidosis, decreased tidal volume, hypercapnia, decreased cardiac output, and hypotension.
A PF ratio of 201-300 is mild disease, 101-200 is moderate disease and <100 is severe disease.
What is asthma?
Reactive airway disease triggered by an allergic reaction.
What is the pathogenesis of asthma?
Asthma is an IgE mediated reaction. The airway narrows, and the disease is marked by dyspnea and expiratory wheezing. Cellular level changes include bronchial smooth muscle hypertrophy, goblet cell hyperplasia, thickening of the basement membranes, proliferation of eosinophils, and bronchial mucous plugs. These changes lead to air trapping which causes decreased alveolar perfusion, increased alveolar gas pressure, decreased ventilation and a creased V/Q ratio. Hyperventilation also occurs secondary to increased lung volumes which can cause CO2 retention and respiratory acidosis. The presence of respiratory acidosis is a precursor to respiratory failure.
What are symptoms during an asthma attack?
Chest constriction, expiratory wheezing, prolonged expiration, tachycardia, and tachypnea. Severe attacks are accompanied by the use of accessory muscles and inspiratory/expiratory wheezing. A silent chest and PaO2 <70 mmHg are signs of impending death.
How is asthma triggered in children?
Exacerbations in children are usually triggered by viral infections. In children, the most common of these is RSV.
What are clinical manifestations of RSV?
Expiratory wheezing, faint breath sounds, and sometimes a barrel chest. In severe cases they may have retractions, nasal flaring and accessory muscle use.
What is COPD?
Results in obstruction of airflow and is typically not reversible and is progressive.
What are risk factors to COPD?
Smoking, occupational dusts and chemicals, and indoor air pollutants.
What are the two main types of COPD?
Emphysema and chronic bronchitis
What is the genetic component of COPD?
An inherited mutation in the alpha 1 antitrypsin gene causes emphysema to develop at an early age, even in persons who do not use tobacco products.
