FRC
Also written as: FRC — Functional Residual Capacity
Functional residual capacity; the volume of air remaining in the lungs after normal, passive expiration.
Full Definition
Functional residual capacity (FRC) represents the lung volume at which the inward elastic recoil of the lungs is balanced by the outward elastic recoil of the chest wall. It consists of the expiratory reserve volume plus the residual volume, typically measuring about 2,300 mL in healthy adults. FRC serves as a reservoir for gas exchange between breaths and helps maintain alveolar stability. Conditions such as ARDS, pneumonia, or restrictive lung diseases can significantly reduce FRC, while emphysema may increase it. Understanding FRC changes helps respiratory therapists optimize PEEP settings and ventilation strategies.
Usage
Usage note: Distinguish from other lung capacity measurements; typically expressed in mL or L.
In Context
- "PEEP was increased to 8 cmH2O to help restore the patient's reduced FRC." — ARDS management protocol
- "Pulmonary function tests revealed an elevated FRC consistent with emphysema." — Pulmonary function report