Monitoring free flaps and replanted digits via perfusion index - A proof of concept study

BACKGROUND: Early detection and treatment of vascular complications in replanted digits is essential for the survival. The perfusion index (PI) represents a marker of peripheral perfusion as it shows the ratio of pulsatile to non-pulsatile blood flow. OBJECTIVE: To evaluate the feasibility and applicability of the PI as a monitoring tool for free flaps and replanted digits by measuring the inter- and intraindividual changes in PI. METHODS: Five patients were postoperatively monitored according to intern standards by hourly clinical evaluation. Additionally, a pulse oximeter with SET-technology (R) (Masimo Radial 7, Masimo Corporation, Irvine, USA) was added with a LNCS (R) Red TFA-1 SpO2 sensor (Masimo Corporation, Irvine, USA) and respectively a LNCS (R) Neo-3 neonatal finger clip to evaluate the perfusion via PI and SpO2. RESULTS: All patients showed sufficient perfusion in clinical controls. There was no detectable vascular complication during follow-up. Mean perfusion index was 0.93 with a median of 0.44. The patients showed a mean SpO2 of 90.59% with a median of 89.21%. CONCLUSION: Our results show a great intra- and interindividual range of PI and SpO2. SpO2 provided an even greater range than PI. Trends in intraindividual PI changes may be a promising monitoring tool for free flaps and replanted digits.