Answer:
In a flow volume loop, the x-axis typically represents volume or lung capacity, while the y-axis represents flow rate. Here's a breakdown of the terms you've mentioned:
1. **Exp vs Insp Curves**:
- **Exp** stands for Expiration, representing airflow during exhalation.
- **Insp** stands for Inspiration, representing airflow during inhalation.
2. **Width of Loop**:
- The width of the loop refers to the horizontal span between the beginning and the end of the loop on the x-axis. It can indicate the dynamic range of lung volumes explored during the maneuver.
3. **Point on X-axis most medial**:
- The point on the x-axis most medial refers to the point closest to the origin on the x-axis. In other words, it's the starting point of the loop, usually representing the functional residual capacity (FRC) or end-expiratory lung volume.
4. **Point on the X-axis most lateral**:
- The point on the x-axis most lateral refers to the point farthest from the origin on the x-axis. It typically represents the total lung capacity (TLC) or maximum lung volume.
5. **Intrathoracic Obstructions (Mediastinal Mass) vs Extrathoracic (Vocal Cord Paralysis)**:
- Intrathoracic obstructions, such as a mediastinal mass, primarily affect the expiratory curve by limiting airflow during exhalation.
- Extrathoracic obstructions, such as vocal cord paralysis, primarily affect the inspiratory curve by limiting airflow during inhalation.
6. **What Affects Both Curves**:
- Conditions affecting both curves would typically be those impacting overall lung function or airway patency, regardless of the phase of respiration. For example:
- Chronic obstructive pulmonary disease (COPD) can affect both curves due to airway narrowing and reduced lung elasticity.
- Restrictive lung diseases, such as pulmonary fibrosis, can also affect both curves by reducing lung compliance and limiting both inspiration and expiration.
- Neuromuscular disorders affecting respiratory muscles can lead to abnormalities in both the inspiratory and expiratory curves.
