Intraoperative TTFM uses pulsatility index (PI) as a parameter. A PI less than what value generally indicates satisfactory graft flow?

• A. PI less than 2 indicates good graft flow.
• B. PI greater than 3 indicates good graft flow.
• C. PI is not used in TTFM.
• D. PI equals 5 is ideal.

Answer: (A)

Pulsatility index is a measure of flow stability and downstream resistance in the graft during transit-time flow measurement. A low PI means the graft is delivering steady, less resistive flow, which is what you want after anastomosis. When the PI is under about 2, it Generally indicates satisfactory graft flow with good run-off and minimal resistance. If the PI is higher—say above 3—it suggests increased resistance or issues at the anastomosis, in the graft, or from distal runoff, which can mean inadequate or turbulent flow despite a seemingly normal mean flow. So the threshold most often used is a PI under 2 for satisfactory graft perfusion. The other statements are not correct because a higher PI signals problems, PI is indeed used in TTFM, and a value like 5 is not considered ideal.