Multisite Peripheral Photoplethysmography Captures Intra-Aortic Balloon Pump Counterpulsation and Weaning State in Cardiogenic Shock

BACKGROUND: Intra-aortic balloon pump (IABP) counterpulsation raises aortic diastolic pressure every cycle (1:1) or alternate cycles (1:2, weaning). Whether they reach peripheral photoplethysmography (PPG) is unknown; 1 report described 1:1 only. CASE SUMMARY: An 82-year-old man in IABP-supported cardiogenic shock had finger and thenar PPG on 1:1, 1:2, removal, and twice afterward. An augmented diastolic peak appeared on every finger beat on 1:1 and alternate beats on 1:2, barring ectopy, and none afterward. Perfusion index reached a nadir at removal and rose through recovery; finger-thenar coherence followed a similar trend. DISCUSSION: Peripheral PPG encoded assist ratio and weaning state. The augmented peak was proportionally larger at the finger than in the aorta, raising the hypothesis that it reflects root- and arch-supplied territories. TAKE-HOME MESSAGE: Ordinary peripheral PPG carries a beat-resolved signature of IABP counterpulsation and of the weaning course, without vascular access.