The fast flush test--is the clinical comparison equivalent to its in vitro simulation?

Area of Science:

• Cardiovascular physiology
• Medical device engineering
• Anesthesiology

Background:

• The fast flush (FL) test, an in vitro simulation, previously validated the dynamic response measurement of blood pressure monitoring systems.
• The FL test was shown to be equivalent to the gold standard square wave (SW) test for dynamic response assessment.
• In vitro simulation conditions are reproducible in vivo during cardiopulmonary bypass (CPB) and circulatory arrest.

Purpose of the Study:

• To verify the validity of the FL test in vivo under clinical conditions, extending previous in vitro findings.
• To assess whether the patient's arterial tree influences the dynamic characteristics of fluid-filled manometers.

Main Methods:

• Studied 14 patients undergoing surgery requiring CPB, measuring arterial manometer dynamic response during pulsatile and non-pulsatile CPB.
• Recorded dynamic response during circulatory arrest in 4 patients and compared in vitro and in vivo manometer performance in 3 patients.
• Utilized a fluid-filled manometer connected to a transducer, recording arterial pressures and FL test waveforms via a monitor.

Main Results:

• The arterial pressure measuring system's dynamic response remained consistent across normal pulsatile flow, CPB, and circulatory arrest.
• The dynamic response of the fluid-filled manometer was identical in vivo and in vitro.
• Clinical conditions during CPB and circulatory arrest effectively replicate the in vitro FL test simulation model.

Conclusions:

• The FL test is validated for in vivo use, confirming its accuracy in clinical settings, including CPB and circulatory arrest.
• The dynamic characteristics of fluid-filled manometers are independent of the patient's vasculature.
• The FL test provides a reliable method for assessing blood pressure monitoring system dynamics in diverse clinical scenarios.