flow-volume loop
Graphical representation of airflow versus lung volume during forced expiration and inspiration, used to diagnose respiratory conditions.
Full Definition
A flow-volume loop is a diagnostic graph created during spirometry that plots expiratory and inspiratory flow rates against lung volume throughout a complete breathing cycle. The patient performs forced expiratory and inspiratory maneuvers while the spirometer records both flow and volume data simultaneously. The resulting loop shows peak expiratory flow, expiratory flow at various lung volumes, and inspiratory flow patterns. Different respiratory conditions produce characteristic loop shapes: obstructive diseases create a scooped expiratory curve, restrictive diseases show reduced loop size, and upper airway obstruction produces flattened portions. This test provides more detailed information than simple spirometric values alone and helps distinguish between various types of respiratory pathology.
In Context
- "The flow-volume loop demonstrated the characteristic scooping pattern consistent with chronic obstructive pulmonary disease." — Pulmonary function interpretation
- "Analysis of the flow-volume loop revealed flattening of both inspiratory and expiratory curves, suggesting fixed upper airway obstruction." — Diagnostic report