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Published on: November 24, 2014
Pulsatility index variations using two different transit-time flowmeters in coronary artery bypass surgery
Håvard B Nordgaard1, Nicola Vitale, Rafael Astudillo
1Department of Circulation and Medical Imaging, The Norwegian University of Science and Technology, N-7489 Trondheim, Norway. haavardnordgaard@gmail.com
Summary
Different filter settings on transit-time flowmeters significantly impact pulsatility index (PI) measurements in coronary artery bypass grafting (CABG). Always specify the flowmeter type and its settings when reporting graft flow data.
Area of Science:
- Cardiovascular Surgery
- Medical Device Technology
- Hemodynamics
Background:
- Transit-time flow measurement is crucial for intra-operative assessment in coronary artery bypass grafting (CABG).
- Commonly used flowmeters (MediStim ASA, Transonic Inc.) have differing default filter settings (20 Hz vs. 10 Hz).
- Discrepancies in filter settings can lead to variations in flow measurements and reported results.
Purpose of the Study:
- To compare pulsatility index (PI) values obtained from MediStim and Transonic flowmeters during CABG.
- To evaluate the impact of varying filter settings on flow patterns within the same grafts.
Main Methods:
- Simultaneous measurement of graft flow and PI using MediStim and Transonic flowmeters in 19 bypass grafts.
- Assessment of eight grafts under diverse digital filter settings (5, 10, 20, 30, 50, 100 Hz).
Main Results:
- The Transonic flowmeter yielded substantially lower PI values compared to the MediStim flowmeter.
- Increasing the filter setting on the flowmeter led to a considerable increase in PI.
- Lower filter settings in the Transonic flowmeter resulted in smoother flow curves.
Conclusions:
- Filter setting differences explain the lower PI observed with the Transonic flowmeter.
- Variations in filter settings directly influence PI measurements.
- Caution is advised when comparing flow values and indexes; the specific flowmeter and its settings must be documented.
