BoardsBridgeArterial Line Waveform Damping
Underdamped vs overdamped systems, the square-wave fast-flush test, and when to trust (or replace) the tracing
Damping describes how the tubing-transducer column absorbs the pressure pulse; an overdamped system blunts the upstroke and underestimates SBP/DBP extremes, an underdamped (resonant) system exaggerates them. The fast-flush square-wave test is the bedside discriminator — count oscillations as the trace returns to baseline.
If you forget
**Fast-flush (square-wave) test is the bedside discriminator** — snap the flush valve, watch the square wave, count oscillations before baseline.
Board trap
Key numbers
- Optimal damping coefficient ζ = 0.4-0.7 (≈0.7 in most OR setups)
- Natural frequency fn > ~25 Hz for adult arterial monitoring systems
- Fast-flush test: optimal = 1-2 oscillations before baseline
- Pressure bag: 300 mmHg to drive continuous 3 mL/hr flush
- Use tubing ≤48 in to preserve fn above resonance zone
Uri Rozen, MD — Licensed Physician, Israel
Source guidelines: ASA SCA Perioperative TEE 2010 · ASA SCA Perioperative TEE 2010
Re-review cadence: 12 months from reviewed date.
Related on BoardsBridge
Card ID: waveform-damping · Path: aba.monitoring.arterial-line.waveform-damping