chapter 23 disorders of ventilation and gas exchange n.
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Essentials of Pathophsiology. Chapter 23 Disorders of Ventilation and Gas Exchange. Pleural, musculoskeletal, and myocardial pain are similar in description and almost impossible to differentiate.

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pre lecture quiz true false

Pleural, musculoskeletal, and myocardial pain are similar in description and almost impossible to differentiate.

  • Extrinsic or atopic asthma is typically initiated by a type I hypersensitivity reaction induced by exposure to an extrinsic antigen or allergen, such as dust mite allergens, cockroach allergens, and animal dander.
  • Persons with emphysema are often labeled as “blue bloaters” because of the chronic hypoxemia and eventual right-sided heart failure with peripheral edema.
  • Cystic fibrosis is manifested by pancreatic exocrine deficiency and a noted decrease in levels of sodium chloride in the sweat.
  • Hypercapnia refers to an abnormal increase in oxygen levels.
Pre lecture quiz True/false






pre lecture quiz

A pleural __________ refers to an abnormal collection of fluid in the pleural cavity.

  • __________ is a leading cause of chronic illness in children and is responsible for a significant number of lost school days; it is also the most frequent admitting diagnosis in children’s hospitals.
  • A __________ pneumothorax, a life-threatening condition, occurs when the intrapleural pressure exceeds atmospheric pressure, permitting air to enter but not leave the pleural space.
  • A pulmonary __________ develops when a blood-borne substance lodges in a branch of the pulmonary artery and obstructs the flow.
  • Corpulmonale refers to __________-sided heart failure resulting from primary lung disease and involves hypertrophy and eventual failure of that ventricle.
Pre lecture quiz
  • Asthma
  • Effusion
  • Embolism
  • Right
  • Tension
causes of respiratory failure

Hypoventilation  hypercapnia, hypoxia

    • Depression of the respiratory center
    • Diseases of respiratory nerves or muscles
    • Thoracic cage disorders
  • Ventilation–perfusion mismatching
  • Impaired diffusion  hypoxemia but not hypercapnia
    • Interstitial lung disease
    • ARDS
    • Pulmonary edema
    • Pneumonia
Causes of Respiratory Failure

PO2 <60 mm Hg

    • Cyanosis
  • Impaired function of vital centers
    • Agitated or combative behavior, euphoria, impaired judgment, convulsions, delirium, stupor, coma
    • Retinal hemorrhage
    • Hypotension and bradycardia
  • Activation of compensatory mechanisms
    • Sympathetic system activation

PCO2 >50 mm Hg

  • Respiratory acidosis
    • Increased respiration
    • Decreased nerve firing
      • Carbon dioxide narcosis
      • Disorientation, somnolence, coma
    • Decreased muscle contraction
      • Vasodilation
        • Headache; conjunctival hyperemia; warm, flushed skin

CO2 + H2O H2CO3 H+ + HCO3-


Tell whether the following statement is true or false.

Both hypercapnia and hypoxemia will lead to respiratory failure if untreated.



Rationale:In hypercapnia (PCO2 >50 mm Hg), tissues accumulate carbon dioxide; in hypoxemia (PO2 <60 mm Hg), less oxygen is delivered to the tissues. In both cases, gas exchange is impaired, and respiratory failure will result unless the conditions are corrected (with oxygen, mechanical ventilation, etc.).

pleural disorders decrease ventilation

Parietal pleura lines the thoracic wall and superior aspect of the diaphragm

Visceral pleura covers the lung

Pleural cavity or space between the two layers contains a thin layer of serous fluid

Pleural Disorders Decrease Ventilation

Mr. K presents himself with a stab wound

  • Now he is having breathing problems, and his breath sounds are diminished on the side with the wound
  • His trachea seems to be slanting toward the other side of his chest, and his heart sounds are displaced away from the wound
  • He has an increased respiration rate and blood pressure, is pale and sweating with bluish nail beds, and has no bowel sounds


  • Explain the effects of the wound

Air enters the pleural cavity

  • Air takes up space, restricting lung expansion
  • Partial or complete collapse of the affected lung
    • Spontaneous: an air-filled blister on the lung ruptures
    • Traumatic: air enters through chest injuries
      • Tension: air enters pleural cavity through the wound on inhalation but cannot leave on exhalation
      • Open: air enters pleural cavity through the wound on inhalation and leaves on exhalation
open pneumothorax
Open Pneumothorax

Air goes out

Air Comes in

tension pneumothorax
Tension Pneumothorax

Air comes in

Air is trapped


Tell whether the following statement is true or false.

Open pneumothorax is more life-threatening than tension pneumothorax.



Rationale:In open pneumothorax, inhaled air compresses the affected side’s lung, but during exhalation, the lung reinflates somewhat. In tension pneumothorax, a sort of one-way valve exists: the air enters the affected side during inhalation, but is unable to leave when the patient exhales. Therefore, all of this air exerts increased pressure on the organs of the thoracic cage. Unless the pressure is relieved, tension pneumothorax is fatal.

pleural effusion fluid in the pleural cavity

Hydrothorax: serous fluid

Empyema(em-pī-ē-mə) : pus

Chylothorax: lymph

Hemothorax: blood

PleuralEffusion—Fluidin the Pleural Cavity

an accumulation of fluid in one or both pleural cavities, often resulting from disease of the heart or kidneys

fluid in the pleural space secondary to leakage from the thoracic duct

obstructive airway disorders

Bronchial asthma

  • Chronic obstructive airway diseases
    • Chronic bronchitis
    • Emphysema
    • Bronchiectasis
    • Cystic fibrosis
Obstructive Airway Disorders
pathogenesis of bronchial asthma
Pathogenesis of Bronchial Asthma

Early Phase



Cytokine Release

Muscle Spasm

Late Phase

Mast Cell Activation

Vascular porosity

Edema and WBC infiltration

Epithelial Damage

Muscle Spasm with edema

extrinsic atopic asthma

Type I hypersensitivity

Mast cells’ inflammatory mediators cause acute response within 10–20 minutes

Treat with inhalers

Airway inflammation causes late-phase response in 4–8 hours

Treat with antiflamatory

Extrinsic (Atopic) Asthma


Mast cells release



WBCs enter region

and release more



intrinsic nonatopic asthma

Respiratory infections

    • Epithelial damage, IgE production
  • Exercise, hyperventilation, cold air
    • Loss of heat and water may cause bronchospasm
  • Inhaled irritants
    • Inflammation, vagal reflex
  • Aspirin and other NSAIDs
    • Abnormal arachidonic acid metabolism
Intrinsic (Nonatopic) Asthma
airway obstruction in asthma
Airway Obstruction in Asthma















airflow limitation


Which of the following occurs in asthma?

  • Airway inflammation
  • Bronchospasm
  • Decreased ability to clear mucus
  • All of the above

All of the above

Rationale:Inflammatory mediators lead to airway inflammation, edema of the mucous lining of the airways, bronchospasm, and impaired ability to clear secretions. All of these things cause the airways to narrow during an asthma attack.

chronic obstructive pulmonary disorders


    • Enlargement of air spaces and destruction of lung tissue
  • Chronic obstructive bronchitis
    • Obstruction of small airways
  • Bronchiectasis
    • Infection and inflammation destroy smooth muscle in airways, causing permanent dilation
Chronic Obstructive Pulmonary Disorders

the bronchi are distended, characterized by sudden violent coughing and copious expectoration of sputum, and which often become infected

mechanisms of copd

Inflammation and fibrosis of bronchial wall

  • Hypertrophied mucus glands  excess mucus
    • Obstructed airflow
  • Loss of alveolar tissue
    • Decreased surface area for gas exchange
  • Loss of elastic lung fibers
    • Airway collapse, obstructed exhalation, air trapping
Mechanisms of COPD

Mechanism of COPD

A) Inflammation, Fibrosis

B) Hypersecretion of mucus

C) Destruction of elastic fibers that hold the airways open


Neutrophils in alveoli secrete trypsin

    • Increased neutrophil numbers due to inhaled irritants can damage alveoli
  • Alpha1-antitrypsin inactivates the trypsin before it can damage the alveoli
    • A genetic defect in alpha1-antitrypsin synthesis leads to alveolar damage
chronic bronchitis

Chronic irritation of airways

    • Increased number of mucus cells
    • Mucus hypersecretion
  • Productive cough
pink puffers vs blue bloaters

Pink puffers (usually emphysema)

    • Increase respiration to maintain oxygen levels
    • Dyspnea; increased ventilatory effort
    • Use accessory muscles; pursed-lip breathing
  • Blue bloaters (usually bronchitis)
    • Cannot increase respiration enough to maintain oxygen levels
    • Cyanosis and polycythemia
    • Corpulmonale
Pink Puffers vs. Blue Bloaters

Which chronic obstructive pulmonary disease primarily affects the alveoli?

  • Asthma
  • Emphysema
  • Chronic bronchitis
  • Bronchiectasis (dilitation)


Rationale:In emphysema, alveolar walls are destroyed. The other chronic pulmonary diseases listed primarily affect the airways.

copd and blood ph


  • In what range will a COPD client’s blood pH fall?
    • Why?
COPD and Blood pH

Normal when stabilized & down to 7.3 unstabilized

CO2 +H2O H2CO3 H+ + HCO3-

Venous blood gas

Respiratory acidosis(lung induced): Low pH, High CO2, Low HCO3-

Metabolic (tissue induced): Low pH, High CO2, Normal HCO3-

consequences of copd

Which step in this flow chart will cause the central chemoreceptors to increase respiration?

Which will cause the peripheral chemoreceptors to increase respiration?

Consequences of COPD



ability to


stale air in


low O2








A client with chronic bronchitis has a barrel chest and cyanosis. His pulse oximeter reads 86% oxygenation. His PO2 is 54 mm Hg. His PCO2 is 56 mm Hg.

  • He is put on low-flow oxygen but complains of shortness of breath. Somebody turns the O2 flow up. He is found in a coma with a PCO2 of 59 mm Hg and a blood pH of 7.2.


  • What was the cause of the coma? Why?
cystic fibrosis

Recessive disorder in chloride transport proteins

    • High concentrations of NaCl in the sweat
    • Less Na+ and water in respiratory mucus and in pancreatic secretions
      • Mucus is thicker
        • Obstructs airways
        • Obstructs pancreatic and biliary ducts
Cystic Fibrosis
pathogenesis of cystic fibrosis
Pathogenesis of Cystic Fibrosis

Cystic Fibrosis Transmembrane Regulator Gene Failure

cystic fibrosis manifestations


  • A client with cystic fibrosis is having respiratory problems and:
    • Digestive problems
    • Flatulence
    • Steatorrhea
    • Weight loss


  • He does not understand why a respiratory disease would cause these problems. How would this be explained to the client?
Cystic Fibrosis Manifestations

Steatorrhea is the presence of excess fat in feces. Stools may also float due to excess lipid, have an oily appearance and be especially foul smelling.

pulmonary blood flow

In a COPD client, exhalation is inefficient and O2 levels in the lungs decrease

  • If blood goes through the lungs filled with stale air, it will not pick up much oxygen; it might even pick up CO2


  • What will the pulmonary arterioles do?
  • Which side of the heart will be affected? Why?
Pulmonary Blood Flow
disorders of pulmonary blood flow

Pulmonary embolism

  • Pulmonary hypertension
    • Primary
      • Blood vessel walls thicken and constrict
    • Secondary
      • Elevation of pulmonary venous pressure
      • Increased pulmonary blood flow
      • Pulmonary vascular obstruction
      • Hypoxemia
Disorders of Pulmonary Blood Flow

Results of Pulmonary Hypertension

Occluded pulmonary artery

cor pulmonale

Right-sided heart failure secondary to respiratory disease

    • Decreased lung ventilation
    • Pulmonary vasoconstriction
    • Increased workload on right heart
    • Decreased oxygenation
    • Kidney releases erythropoietin  more RBCs made
    • Polycythemia makes blood more viscous
    • Increased workload on heart
Cor Pulmonale
acute respiratory distress syndrome ards

Exudate enters alveoli

    • Blocks gas exchange
    • Makes inhalation more difficult
  • Neutrophils enter alveoli
    • Release inflammatory mediators
    • Release proteolytic enzymes
Acute Respiratory Distress Syndrome (ARDS)

Tell whether the following statement is true or false.

Patients suffering from ARDS will be not necessarily be hypoxemic.



Rationale:In ARDS the alveoli are filled with exudate, decreasing the available surface area for gas exchange. If gas exchange decreases, poorly oxygenated or unoxygenated blood is sent to the tissues (hypoxemia).