1. Chapter 31: Disorders of Ventilation and Gas Exchange

2. Gases of Respiration Primary function of respiratory system Remove CO2
Addition of O2
Insufficient exchange of gasses
Hypoxemia
Hypercapnia

3. Hypoxemia Hypoxemia results from An inadequate O2 in the air
Disease of the respiratory system
Dysfunction of the neurological system
Alterations in circulatory function
Mechanisms
Hypoventilation
Impaired diffusion of gases
Inadequate circulation of blood through the pulmonary capillaries
Mismatching of ventilation and perfusion

4. Manifestations of Hypoxemia #1
Mild hypoxemia
Metabolic acidosis
Increase in heart rate
Peripheral vasoconstriction
Diaphoresis
Increase in blood pressure
Slight impairment of mental performance

5. Manifestations of Hypoxemia #2
Chronic hypoxemia
Manifestations of chronic hypoxia may be insidious in onset and attributed to other causes.
Compensation masks condition.
Increased ventilation
Pulmonary vasoconstriction
Increased production of red blood cells
Cyanosis

6. Hypercapnia Increased arterial PCO2
Caused by hypoventilation or mismatching of ventilation and perfusion
Effects
Acid–base balance (decreased pH, respiratory acidosis)
Kidney function
Nervous system function
Cardiovascular function

7. Disorders of the Pleura
Pleural effusion: abnormal collection of fluid in the pleural cavity
Transudate or exudate, purulent (containing pus), chyle, or sanguineous (bloody)
Hemothorax
Pleuritis
Chylothorax
Atelectasis
Empyema

8. Types of Pneumothoraxes
Spontaneous Pneumothorax
Occurs when an air-filled blister on the lung surface ruptures
Traumatic Pneumothorax
Caused by penetrating or nonpenetrating injuries
Tension Pneumothorax
Occurs when the intrapleural pressure exceeds atmospheric pressure

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

10. Characteristics and Symptoms of Pleural Pain
Abrupt in onset
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.

11. Pleural Effusion Definition
An abnormal collection of fluid in the pleural cavity
Types of fluid
Transudate
Exudate
Purulent drainage (empyema)
Chyle
Blood

12. Diagnosis and Treatment of Pleural Effusion
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

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

14. Types of Atelectasis Primary Present at birth Secondary
Develops in the neonatal period or later in life

15. Question #1
Which of the following is a disorder caused by abnormal accumulation of fluid in the pleural space?
Pneumothorax
Pleural effusion
Atelectasis
Hypercapnia

16. Answer to Question #1 B. Pleural effusion
Rationale: Pleural effusion can be caused by transudate, exudate, chyle, or other fluid.

17. Physiology of Airway Disease
Upper respiratory tract
Trachea and major bronchi
Lower respiratory tract
Bronchi and alveoli
Creation of negative pressure
Effects of CO2/pH
Role of inflammatory mediators
Increase airway responsiveness by:
Producing bronchospasm
Increasing mucus secretion
Producing injury to the mucosal lining of the airways

18. Functions of Bronchial Smooth Muscle
The tone of the bronchial smooth muscles surrounding the airways determines airway radius.
The presence or absence of airway secretions influences airway patency.
Bronchial smooth muscle is innervated by the autonomic nervous system.
Parasympathetic: vagal control
Bronchoconstrictor
Sympathetic: β2-adrenergic receptors
Bronchodilator

19. Factors Contributing to the Development of an Asthmatic Attack
Allergens
Respiratory tract infections
Exercise
Drugs and chemicals
Hormonal changes and emotional upsets
Airborne pollutants
Gastroesophageal reflux

20. Factors Involved in the Pathophysiology of Asthma
Genetic
Atopy
Early versus late phase
Environmental
Viruses
Allergens
Occupational exposure

21. Classifications of Asthma Severity
Mild intermittent
Mild persistent
Moderate persistent
Severe persistent

22. Question #2
Which of the following has not been implicated in the development of asthma?
Allergens
Respiratory tract infections
Diet
Drugs and chemicals
Hormonal changes and emotional upsets
Airborne pollutants
Gastroesophageal reflux

23. Answer to Question #2 C. Diet
Rationale: Diet does not affect the respiratory tract other than via allergic reactions.

24. Chronic Obstructive Airway Disease
Inflammation and fibrosis of the bronchial wall
Hypertrophy of the submucosal glands
Hypersecretion of mucus
Loss of elastic lung fibers
Impairs the expiratory flow rate, increases air trapping, and predisposes to airway collapse
Alveolar tissue
Decreases the surface area for gas exchange

25. Causes of Chronic Obstructive Airway Disease
Chronic bronchitis
Emphysema
Bronchiectasis
Cystic fibrosis

26. Types of Chronic Obstructive Pulmonary Disease
Emphysema
Enlargement of air spaces and destruction of lung tissue
Types: centriacinar and panacinar
Chronic Obstructive Bronchitis
Obstruction of small airways

27. Characteristics of Type A Pulmonary Emphysema
Smoking history
Age of onset: 40 to 50 years
Often dramatic barrel chest
Weight loss
Decreased breath sounds
Normal blood gases until late in disease process
Cor pulmonale only in advanced cases
Slowly debilitating disease

28. Characteristics of Type B Chronic Bronchitis #1
Smoking history
Age of onset 30 to 40 years
Barrel chest may be present
Shortness of breath, a predominant early symptom
Rhonchi often present
Sputum frequent, an early manifestation

29. Characteristics of Type B Chronic Bronchitis #2
Often dramatic cyanosis
Hypercapnia and hypoxemia may be present.
Frequent cor pulmonale and polycythemia
Numerous life-threatening episodes due to acute exacerbations

30. Bronchiectasis Permanent dilation of the bronchi and bronchioles
Secondary to persisting infection or obstruction
Manifestations
Atelectasis
Obstruction of the smaller airways
Diffuse bronchitis
Recurrent bronchopulmonary infection
Coughing; production of copious amounts of foul- smelling, purulent sputum; and hemoptysis
Weight loss and anemia are common.

31. Cystic Fibrosis Definition
An autosomal recessive disorder involving fluid secretion in the exocrine glands and the epithelial lining of the respiratory, gastrointestinal, and reproductive tracts
Cause
Mutations in a single gene on the long arm of chromosome 7 that encodes for the cystic fibrosis transmembrane regulator (CFTR), which functions as a chloride (Cl−) channel in epithelial cell

32. Manifestations of Cystic Fibrosis
Pancreatic exocrine deficiency
Pancreatitis
Elevation of sodium chloride in the sweat
Excessive loss of sodium in the sweat
Nasal polyps
Sinus infections
Cholelithiasis

33. Diffuse Interstitial Lung Diseases
Definition
A diverse group of lung disorders that produce similar inflammatory and fibrotic changes in the interstitium or interalveolar septa of the lung
Types
Sarcoidosis
The occupational lung diseases
Hypersensitivity pneumonitis
Lung diseases caused by exposure to toxic drugs

34. Occupational Lung Diseases
Pneumoconioses
The inhalation of inorganic dusts and particulate matter
Hypersensitivity diseases
The inhalation of organic dusts and related occupational antigens
Byssinosis: cotton workers; has characteristics of the pneumoconioses and hypersensitivity lung disease

35. Pulmonary Embolism Development
A blood-borne substance lodges in a branch of the pulmonary artery and obstructs the flow
Types
Thrombus: arising from DVT
Fat: mobilized from the bone marrow after a fracture or from a traumatized fat depot
Amniotic fluid: enters the maternal circulation after rupture of the membranes at the time of delivery

36. Pulmonary Hypertension
Signs and Symptoms of Secondary Pulmonary Hypertension
Dyspnea and fatigue
Peripheral edema
Ascites
Signs of right heart failure (cor pulmonale)
A disorder characterized by an elevation of pressure within the pulmonary circulation
Pulmonary arterial hypertension

37. Cor Pulmonale
Right heart failure resulting from primary lung disease and long-standing primary or secondary pulmonary hypertension
Involves hypertrophy and the eventual failure of the right ventricle
Manifestations include the signs and symptoms of the primary lung disease and the signs of right-sided heart failure.

38. Acute Respiratory Distress Syndrome
A number of conditions may lead to ALI/ARDS.
They all produce similar pathologic lung changes that include diffuse epithelial cell injury with increased permeability of the alveolar–capillary membrane.

39. Causes of ARDS Aspiration of gastric contents
Major trauma (with or without fat emboli)
Sepsis secondary to pulmonary or nonpulmonary infections
Acute pancreatitis
Hematologic disorders
Metabolic events
Reactions to drugs and toxins

40. Causes of Respiratory Failure
Impaired ventilation
Upper airway obstruction
Weakness of paralysis of respiratory muscles
Chest wall injury
Impaired matching of ventilation and perfusion
Impaired diffusion
Pulmonary edema
Respiratory distress syndrome

41. Treatment of Respiratory Failure
Respiratory supportive care directed toward maintenance of adequate gas exchange
Establishment of an airway
Use of bronchodilating drugs
Antibiotics for respiratory infections
Ensure adequate oxygenation

42. Question #3
Which of the following has been implicated as a causative factor in right ventricular failure?
Cor pulmonale
Pneumothorax
Cystic fibrosis
ARDS

43. Answer to Question #3 A. Cor pulmonale
Rationale: Cor pulmonale will result in RV failure due to the increase in workload that will result.