Examples of Conditions That Increase Physiological Dead Space

📚 Quick Study Guide

• 🫁 Physiological dead space refers to the portion of the respiratory system where gas exchange does not occur. It's the sum of anatomical dead space (conducting airways) and alveolar dead space (alveoli that are ventilated but not perfused).
• 🌬️ Conditions that increase physiological dead space effectively reduce the efficiency of ventilation.
• 💔 Pulmonary Embolism: Blocks blood flow to alveoli, increasing alveolar dead space.
• 📉 Low Cardiac Output: Reduces pulmonary perfusion, increasing alveolar dead space.
• 🎈 Emphysema: Damages alveolar walls, reducing surface area for gas exchange and creating areas that are ventilated but poorly perfused.
• 🤕 Hypotension: Results in decreased pulmonary capillary perfusion.
• 🔬 Positive Pressure Ventilation: Can over-inflate alveoli and decrease pulmonary blood flow.

🧪 Practice Quiz

1. What is the primary effect of pulmonary embolism on physiological dead space?
   1. A) Decreases anatomical dead space
   2. B) Increases alveolar dead space
   3. C) Decreases alveolar dead space
   4. D) No effect on dead space
2. How does low cardiac output influence physiological dead space?
   1. A) Increases pulmonary perfusion
   2. B) Decreases pulmonary perfusion
   3. C) No effect on pulmonary perfusion
   4. D) Increases oxygen uptake
3. Which lung condition is characterized by damaged alveolar walls, leading to increased physiological dead space?
   1. A) Asthma
   2. B) Pneumonia
   3. C) Emphysema
   4. D) Bronchitis
4. Hypotension can increase physiological dead space by:
   1. A) Increasing pulmonary capillary perfusion
   2. B) Decreasing pulmonary capillary perfusion
   3. C) Dilating the bronchioles
   4. D) Constricting the bronchioles
5. How does positive pressure ventilation potentially increase physiological dead space?
   1. A) By increasing pulmonary blood flow
   2. B) By decreasing pulmonary blood flow
   3. C) By reducing alveolar over-inflation
   4. D) By promoting uniform alveolar ventilation
6. Which of the following directly contributes to alveolar dead space?
   1. A) Blockage of the trachea
   2. B) Perfusion of non-ventilated alveoli
   3. C) Ventilation of non-perfused alveoli
   4. D) Increased anatomical dead space
7. A patient with severe dehydration is likely to experience which of the following regarding physiological dead space?
   1. A) Decreased physiological dead space due to increased blood volume
   2. B) Increased physiological dead space due to reduced blood volume and perfusion
   3. C) No change in physiological dead space
   4. D) Decreased physiological dead space due to reduced ventilation