perfusion index
A noninvasive measure of peripheral perfusion derived from pulse oximetry that reflects the ratio of pulsatile to non-pulsatile blood flow.
Full Definition
The perfusion index (PI) is calculated as the ratio of the pulsatile signal (arterial blood) to the non-pulsatile signal (venous blood, bone, and tissue) detected by pulse oximetry. Normal values range from 0.02% to 20%, with higher values indicating better peripheral perfusion. In cardiovascular anesthesiology, PI serves as an early indicator of changes in peripheral blood flow and can detect hypovolemia, vasoconstriction, or compromised circulation before traditional vital signs change. Low PI values may indicate the need for fluid resuscitation or vasopressor adjustment.
Usage
Usage note: Often abbreviated as PI; ensure context distinguishes from other medical uses of this abbreviation.
In Context
- "The perfusion index dropped significantly following the initiation of cardiopulmonary bypass." — Intraoperative monitoring record
- "Trending perfusion index values helped guide fluid management during the procedure." — Hemodynamic management documentation