Respiratory Failure and VQ Mismatch Quiz
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Questions and Answers

What is the most common cause of hypoxia in respiratory diseases?

  • VQ mismatch (correct)
  • Shunts
  • Alveolar hypoventilation
  • Diffusion deficit

    • When does the effect of gravity on VQ ratio become significant?

  • In healthy individuals
  • In cases of disease (correct)
  • When blood flow is reduced
  • When ventilation is increased

    • What is Type 1 respiratory failure characterized by?

  • Hypercapnia with a high PaO2
  • Hypoxemia with a high CO2
  • Hypoxemia with a normal or low CO2 (correct)
  • Hypercapnia with a normal or low PaO2

    • Pulmonary ventilation increases from apex to base primarily due to:

    Signup and view all the answers

    According to Poiseulle's Law, what is resistance to flow inversely proportional to?

    <p>Radius</p> Signup and view all the answers

    Which structures provide the most resistance to airflow?

    <p>Bronchioles</p> Signup and view all the answers

    Which structures provide the most resistance to perfusion?

    <p>Arterioles</p> Signup and view all the answers

    What happens to bronchioles in response to raised PaCO2?

    <p>They dilate to improve airflow</p> Signup and view all the answers

    What happens to pulmonary arterioles in response to low PaO2?

    <p>They constrict to reduce blood flow</p> Signup and view all the answers

    What varies from the bottom to the top of the lung?

    <p>Ventilation</p> Signup and view all the answers

    What is the result of the variation in blood flow and ventilation from bottom to top of the lung?

    <p>Different arterial and alveolar partial pressures of O2</p> Signup and view all the answers

    What is the normal range for arterial PaO2?

    <p>11-15kPa</p> Signup and view all the answers

    What is the normal range for arterial PaCO2?

    <p>4.6-6.4 kPa</p> Signup and view all the answers

    Hypoxia is characterized by:

    <p>Low PaO2 levels</p> Signup and view all the answers

    Hypercapnia is characterized by:

    <p>High PaCO2 levels</p> Signup and view all the answers

    Abnormal values outside the normal ranges for PaO2 and PaCO2 may indicate:

    <p>Respiratory failure</p> Signup and view all the answers

    What is hypoventilating?

    <p>Inability to exhale which causes CO2 retention</p> Signup and view all the answers

    Respiratory failure is defined as a failure to maintain adequate:

    <p>Gas exchange</p> Signup and view all the answers

    Type 2 respiratory failure is characterized by

    <p>Hypoxemia with a high CO2</p> Signup and view all the answers

    What are the main four physiological causes of respiratory failure?

    <p>Alveolar hypoventilation, diffusion deficit, shunts and VQ mismatch</p> Signup and view all the answers

    Which physiological cause of respiratory failure is characterized by an increase in PaCO2?

    <p>Alveolar hypoventilation</p> Signup and view all the answers

    How can alveolar hypoventilation-induced respiratory failure be corrected?

    <p>Oxygen therapy</p> Signup and view all the answers

    Which type of respiratory failure is associated with alveolar hypoventilation?

    <p>Type II</p> Signup and view all the answers

    What is the characteristic effect of alveolar hypoventilation on minute ventilation?

    <p>Increase of PaCO2</p> Signup and view all the answers

    What is minute ventilation?

    <p>amount of air inhaled and exhaled per minute</p> Signup and view all the answers

    Define perfusion

    <p>Blood that flows through the capillaries that surround the alveoli</p> Signup and view all the answers

    Define alveolar dead space

    <p>the part of the lungs where gas exchange cannot occur due to the absence of adequate blood flow or ventilation.</p> Signup and view all the answers

    What is a characteristic associated with alveolar hypoventilation

    <p>All of the above</p> Signup and view all the answers

    Which physiological cause of respiratory failure is related to an impairment in the transfer of gases across the alveolar-capillary method

    <p>Diffusion deficit</p> Signup and view all the answers

    What is the main characteristic of a shunt in the context of respiratory failure?

    <p>Venous blood mixing with arterial blood</p> Signup and view all the answers

    Which type of shunt is commonly seen in pediatric cardiac cases and usually reverses?

    <p>Extra pulmonary shunt</p> Signup and view all the answers

    What are the common causes of intra-pulmonary shunt?

    <p>Pus, edema, blood, or tumor in the alveoli</p> Signup and view all the answers

    True or False: Oxygen can correct pure shunt hypoxia.

    <p>False</p> Signup and view all the answers

    What does VQ matching refer to in the context of gas exchange?

    <p>The balance between ventilation and perfusion in alveolar capillaries</p> Signup and view all the answers

    What is the consequence of VQ mismatch?

    <p>Hypoxia in respiratory diseases</p> Signup and view all the answers

    Which of the following can cause VQ mismatch?

    <p>All of the above</p> Signup and view all the answers

    What happens to the PAO2 and the PA-PaO2 gradient in the presence of VQ mismatch?

    <p>PAO2 decreases and the gradient increases</p> Signup and view all the answers

    What is the consequence of ventilation-perfusion (VQ) mismatching on blood leaving relatively healthy alveoli?

    <p>Blood leaving healthy alveoli will have an oxygen saturation of about 97%</p> Signup and view all the answers

    What happens to the oxygen saturation of blood leaving alveoli with suboptimal V/Q ratios?

    <p>O2 saturation decreases</p> Signup and view all the answers

    What is the overall consequence of ventilation-perfusion (VQ) mismatching on the circulation?

    <p>Hypoxemia</p> Signup and view all the answers

    Why does blood leaving relatively healthy alveoli have a high oxygen saturation?

    <p>Due to a flat upper portion of the oxyhaemoglobin dissociation curve</p> Signup and view all the answers

    What is the most common cause of Type 2 respiratory failure?

    <p>Alveolar hypoventilation</p> Signup and view all the answers

    What is diffusion deficit caused by?

    <p>A reduction in gas exchange area</p> Signup and view all the answers

    What are shunts?

    <p>A mixture of venous and arterial blood</p> Signup and view all the answers

    What is the effect of gravity on VQ ratios in the lungs?

    <p>VQ ratios vary from lung apex to base</p> Signup and view all the answers

    What are the three zones established in an upright person based on the relationship between pulmonary arterial pressure, pulmonary venous pressure, and alveolar pressure?

    <p>Zone 1, Zone 2, and Zone 3</p> Signup and view all the answers

    What is Type 1 respiratory failure characterized by?

    <p>Hypoxemia with a normal or low CO2</p> Signup and view all the answers

    How many zones are established in an upright person due to the gravitational effects on pulmonary perfusion?

    <p>3</p> Signup and view all the answers

    Study Notes

    Respiratory Failure: Understanding VQ Mismatch and Regulation

    • Gas exchange in the lungs involves alveolar-blood diffusion and partial pressures of O2 and CO2 exchange, with normal arterial values of PaO2 and PaCO2.
    • Factors that influence gas exchange in health and disease include influential factors such as Fick's principle and ventilation-perfusion VQ matching.
    • VQ ratios vary from lung apex to base due to the effect of gravity on ventilation and perfusion, and the comparison of pulmonary and systemic circulation characteristics.
    • VQ mismatch is the most common cause of hypoxia in respiratory diseases and is of major significance in respiratory failure.
    • Type 1 respiratory failure is characterized by hypoxemia with a normal or low CO2, while Type 2 respiratory failure is characterized by hypoxemia with a high CO2.
    • Respiratory failure can be caused by alveolar hypoventilation, diffusion deficit, shunts, and ventilation-perfusion VQ mismatch.
    • Hypoventilation resulting from a reduction in minute ventilation and an increase in proportion of dead space ventilation is the most common cause of Type 2 respiratory failure.
    • Diffusion deficit is caused by a reduction in gas exchange area due to pathological conditions such as pulmonary fibrosis, oedema, asbestosis, or pneumonia.
    • Shunts occur when venous blood mixes with arterial blood, and can be extra-pulmonary or intra-pulmonary, with the commonest causes being alveolar filling and atelectasis.
    • VQ matching is regulated by altering respiratory bronchiolar and pulmonary arteriolar radius changes in response to raised PaCO2 or low PaO2, which changes resistance and hence flow.
    • The VQ ratio is not uniform throughout the lungs due to gravity, and blood flow and ventilation vary from bottom to top of the lung.
    • The gravitational effects on pulmonary perfusion result in three zones that are established in an upright person, dependent on the relationship between pulmonary arterial pressure, pulmonary venous pressure, and alveolar pressure, with zone 1 established when alveolar pressure exceeds arterial pressure and there is no blood flow, zone 2 established when arterial pressure exceeds alveolar pressure, and blood flow depends on the difference between arterial and alveolar pressures, and zone 3 established when both arterial and venous pressures exceed alveolar pressure, and blood flow depends on the normal arterial-venous pressure difference.

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    Description

    Test your knowledge on respiratory failure and the regulation of VQ mismatch with this informative quiz. Learn about the factors that influence gas exchange in the lungs, the different types of respiratory failure, and the causes of hypoventilation, diffusion deficit, and shunts. Explore how VQ matching is regulated and understand the non-uniformity of the VQ ratio throughout the lungs. Challenge yourself with this quiz and enhance your understanding of respiratory failure and VQ mismatch.

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