Patho: Chapter 31 (Disorders of Ventilation and Gas Exchange)

What is hypoxemia?

A reduction in the oxygen pressure (PO₂) of arterial blood to less than 60 mm Hg

What causes hypoxemia?

• Inadequate amount of oxygen in the air

• Disease of the respiratory system

• Dysfunction of the neurologic system

• Alterations in circulatory function

What are the characteristics/manifestations of hypoxemia?

• Cyanosis

• Increased ventilation

• Sympathetic nervous system activation

• Pulmonary vasoconstriction

• Increased RBC production

• Neurologic changes (combative behavior, euphoria)

• Hypotension

• Bradycardia

What is cyanosis?

Refers to a bluish discoloration of the skin and mucous membranes from excess deoxygenated hemoglobin in small blood vessels

What is Hypercapnia?

An Increase in the carbon dioxide content (PCO₂) of arterial blood to greater than 50 mm Hg.

What causes hypercapnia?

• Hypoventilation

• Ventilation-perfusion (V/Q) mismatch

What is atelectasis?

A partial collapse of the lung or inadequate inflation of a portion of the lung or alveoli.

What causes atelectasis?

• Airway obstruction

• Prolonged immobility

• Underlying lung disease

• Fractured ribs

What are the characteristics/manifestations of atelectasis?

• Partial lung collapse

• Inadequate inflation of alveoli

• Low ventilation compared to perfusion

• Reduced gas exchange

What are the two types of atelectasis?

• Primary atelectasis (present at birth)

• Secondary atelectasis (acquired)

What is Pleural Effusion?

The accumulation of fluid in the intrapleural (pleural) space surrounding the lungs.

What causes pleural effusion?

• Excess fluid formation

• Decreased lymphatic removal of fluid

• Congestive heart failure

• Renal failure

• Liver failure

• Malignancy (cancer)

What are the risk factors for pleural effusion?

• Bacterial pneumonia

• Viral infection

• Pulmonary infarcation

What is a pneumothorax?

The presence of air in the pleural space that causes partial or complete collapse of the lung.

What causes a pneumothorax?

• Rupture of an air-filled bleb on the lung (spontaneous)

• Traumatic injury to the chest or major airways (traumatic)

What are the characteristics/manifestations of a pneumothorax?

• Air in the pleural space

• Partial or complete lung collapse

• Impaired gas exchange

• Reduced lung expansion

What are the two main types of pneumothorax?

• Spontaneous pneumothorax

• Traumatic pneumothorax

What is a spontaneous pneumothorax?

A pneumothorax that occurs without an obvious injury or cause

What is a traumatic pneumothorax?

A pneumothorax caused by direct injury to the chest or major airways.

What are the two types of traumatic pneumothorax?

• Open pneumothorax

• Tension pneumothorax

What is an open pneumothorax?

Air is able to enter during inhalation and leave the pleural cavity during exhalation.

What is a tension pneumothorax?

Air is able to enter during inhalation but cannot leave during exhalation.

What is Asthma?

A chronic inflammatory disorder of the airways characterized by recurring episodes of airflow obstruction and bronchial hyperresponsiveness.

What causes Asthma?

• Genetic predisposition

• Exposure to allergens

• Exposure to irritants and tobacco smoke

• Obesity

• Respiratory tract infections

• Exercise

• Drugs and pollutants

What are the two types of asthma?

• Extrinsic (allergic) asthma

• Intrinsic (non-allergic) asthma

What is the strongest risk factor for asthma?

Genetic predisposition

What is Chronic Obstructive Pulmonary Disease (COPD)?

A group of chronic respiratory disorders characterized by progressive airflow limitation that is not fully reversible.

What causes COPD?

• Smoking cigarettes (primary cause)

• Chronic airway irritation

• Recurrent respiratory infections

What are the characteristics/manifestations of COPD?

• Progressive airflow obstruction

• Difficulty exhaling air

• Dyspnea (shortness of breath)

• Hypoxemia

• Hypercapnia

• Cyanosis

• Increased work of breathing

What is Emphysema?

An incurable lung disease characterized by enlargement of air spaces and destruction of alveolar walls.

What causes Emphysema?

• Smoking cigarettes (primary cause)

• Increased neutrophils in the alveoli

• Excess trypsin activity

• Alpha-1 antitrypsin deficiency (genetic defect)

What are the characteristics/manifestations of emphysema?

• Enlargements of air spaces

• Destruction of alveolar walls

• Irreversible loss of alveolar tissue

• Air trapping in the lungs

• Barrel chest (increased anterior-posterior chest diameter)

• Dyspnea

What is the primary cause of Emphysema?

Smoking cigarettes

How doe the alveoli get destroyed in emphysema?

Inhaled irritants increase the number of neutrophils, which then secrete trypsin, which is known to damage the alveoli.

Besides smoking, what can cause emphysema?

A genetic defect in alpha-1 antitrypsin synthesis leads to alveolar damage. In people with this defect, they have a surplus of trypsin, which damages the alveoli.

What is the function of alpha-1 antitrypsin?

It inactivates trypsin before it can damage the alveoli.

What are pink puffers?

Individuals with emphysema who maintain oxygen levels by increasing their respiratory effort.

What causes the pink puffer appearance?

• Emphysema

• Increased respiratory effort to maintain oxygenation

What are the characteristics/manifestations of pink puffers?

• Lack of cyanosis (“pink”)

• Increased respiration

• Dyspnea

• Increased ventilatory effort

• Use of accessory muscles

• Pursed-lip breathing (“puffer”)

What are blue bloaters (puffers)?

Individuals with chronic bronchitis who cannot maintain adequate oxygenation and often develop right-sided heart failure.

What causes the blue bloater appearance?

• Chronic bronchitis

• Inadequate oxygenation

• Cor pulmonale (right-sided heart failure)

What are the characteristics/manifestations of blue bloaters (puffers)?

• Cyanosis (“blue”)

• Polycythemia

• Inability to increase respiration enough to maintain oxygen levels

• Cor pulmonale (right ventricular enlargement/failure)

• Fluid retention (“bloater”)e]

What is Chronic Bronchitis?

A chronic obstructive pulmonary disease is characterized by obstruction of the major and small airways.

What causes chronic bronchitis?

• Chronic irritation from smoking

• Recurrent respiratory infections

What are the characteristics/manifestations of chronic bronchitis?

• Airway obstruction

• Increased number of mucus-producing cells

• Mucus hypersecretion

• Hypertrophy of submucosal glands in the trachea and bronchi

• Productive cough

• Cyanosis (in advanced disease)

• Fluid retention

Do people with chronic bronchitis have a productive cough?

Yes

What is Bronchiectasis?

A chronic lung disorder characterized by permanent dilation of the bronchi due to destruction of the bronchial muscle wall and elastic supporting tissue.

What causes Bronchiectasis?

• Destruction of the bronchial muscle wall

• Destruction of elastic supporting tissue

• Occurs secondary to other abnormalities or disease

What are the characteristics/manifestations of bronchiectasis?

• Permanent dilation of the bronchi

• Damage to bronchial walls

• Chronic airways disease

• Classified as a COPD

In what range will a COPD client’s blood pH fall?

It becomes more acidic (decreased pH).

What is Cystic Fibrosis?

An autosomal recessive genetic disorder that affects the exocrine glands and causes severe chronic respiratory disease.

What causes Cystic Fibrosis?

• Mutation of the CFTR gene on chromosome 7

• Defective chloride ion transport across epithelial cell membranes.

What are the characteristics/manifestations of Cystic Fibrosis?

• Thick, sticky mucus secretions

• Chronic respiratory infections

• Airway obstruction

• Pancreatic exocrine deficiency

• Elevated sodium chloride in sweat

• Steatorrhea (fatty stools)

• Diarrhea

• Digestive problems

• Abdominal pain

How can new mothers tell their baby has Cystic Fibrosis?

Their babies have salty sweat and steatorrhea.

Besides respiratory disease, what else does Cystic Fibrosis affect?

• Pancreas (pancreatic exocrine deficiency)

• Gastrointestinal tract

• Reproductive tract

• Sweat glands (elevated sodium chloride in sweat)

What is Pulmonary Hypertension?

A disorder characterized by abnormally elevated blood pressure within the pulmonary arterial system.

What are the characteristics/manifestations of pulmonary hypertension?

• Elevated pressure in pulmonary arteries

• Smooth muscle hypertrophy of pulmonary vessels

• Proliferation of the vessel intima

• Increased workload on the right ventricle

• Can lead to right-sided heart failure (cor pulmonale)

What are the two types of pulmonary hypertension?

• Primary pulmonary hypertension

• Secondary pulmonary hypertension

What is Primary pulmonary hypertension?

Pulmonary hypertension that develops on its own.

What is secondary pulmonary hypertension?

Pulmonary hypertension associated with other diseases, usually cardiac or pulmonary.

What causes secondary pulmonary hypertension?

• Elevation of pulmonary venous pressure

• Increased pulmonary blood flow

• Pulmonary vascular obstruction

• Hypoxemia

• COPD

• Heart failure

• Sleep apnea

What is Cor Pulmonale?

Right-sided heart failure resulting from primary lung disease or pulmonary hypertension.

Can bronchitis be associated with Cor Polmonale?

Yes

Do people who have COPD, like emphysema, have a prolonged expiration?

Yes

What is Acute Respiratory Distress Syndrome (ARDS)?

A clinical syndrome characterized by severe dyspnea of rapid onset, hypoxemia, and pulmonary infiltrates.

What causes Acute Respiratory Distress Syndrome (ARDS)?

• Injury to the alveoli and capillaries

• Increased permeability of the alveolar-capillary membrane

• Fluid and proteins leak into the alveoli

• Neutrophil activation and inflammation within the lungs

What are the characteristics/manifestations of Acute Respiratory Distress Syndrome (ARDS)?

• Rapid onset dyspnea

• Hypoxemia

• Pulmonary infiltrates

• Pulmonary edema

• Hyaline membrane formation

• Loss of surfactant

• Decreased lung compliance (stiff lungs)

• Difficult gas exchange

What is an Acute Lung Injury (ALI)?

A less severe forms of ARDS that can progress to ARDS.

What is Respiratory Failure?

A condition in which the respiratory system fails in one or both of its gas exchange functions: oxygenation of blood and removal of carbon dioxide.

What causes Respiratory Failure?

• Hypoventilation

• Depression of respiratory center

• Disease of respiratory nerves or muscles

• Ventilation-perfusion (V/Q) mismatch

• Impaired diffusion

• Interstitial lung disease

• ALI

• ARDS

• Pulmonary edema

• Pneumonia

What are the characteristics of Respiratory Failure?

• Impaired oxygenation of blood (hypoxemia)

• Impaired removal of carbon dioxide (hypercapnia)

• Inadequate gas exchange

• Can occur acutely or superimposed on chronic lung disease

What are the two types of Respiratory Failure?

• Hypoxemic Respiratory Failure (failure of oxygenation)

• Hypercapnic Respiratory Failure (failure to remove carbon dioxide)

Which of the following can cause Respiratory Failure?

All of the above

A client with chronic obstructive pulmonary disease presents who the emergency department with difficulty breathing. Physical examination reveals bluish skin, nail beds, and mucous membranes. Which term correctly describes this condition?

Cyanosis

A client with chronic obstructive pulmonary disease has developed right heart failure. The healthcare provider would document this as:

Cor Pulmonale