Intraoperative Beat-to-Beat Pulse Transit Time (PTT) Monitoring via Non-Invasive Piezoelectric/Piezocapacitive Peripheral Sensors Can Predict Changes in Invasively Acquired Blood Pressure in High-Risk Surgical Patients

Background: Non-invasive tracking of beat-to-beat pulse transit time (PTT) via piezoelectric/piezocapacitive sensors (PES/PCS) may expand perioperative hemodynamic monitoring. This study evaluated the ability for PTT via PES/PCS to correlate with systolic, diastolic, and mean invasive blood pressure (SBP(IBP), DBP(IBP), and MAP(IBP), respectively) and to detect SBP(IBP) fluctuations. Methods: PES/PCS and IBP measurements were performed in 20 patients undergoing abdominal, urological, and cardiac surgery. A Pearson’s correlation analysis (r) between 1/PTT and IBP was performed. The predictive ability of 1/PTT with changes in SBP(IBP) was determined by area under the curve (reported as AUC, sensitivity, specificity). Results: Significant correlations between 1/PTT and SBP(IBP) were found for PES (r = 0.64) and PCS (r = 0.55) (p < 0.01), as well as MAP(IBP)/DBP(IBP) for PES (r = 0.6/0.55) and PCS (r = 0.5/0.45) (p < 0.05). A 7% decrease in 1/PTT(PES) predicted a 30% SBP(IBP) decrease (0.82, 0.76, 0.76), while a 5.6% increase predicted a 30% SBP(IBP) increase (0.75, 0.7, 0.68). A 6.6% decrease in 1/PTT(PCS) detected a 30% SBP(IBP) decrease (0.81, 0.72, 0.8), while a 4.8% 1/PTT(PCS) increase detected a 30% SBP(IBP) increase (0.73, 0.64, 0.68). Conclusions: Non-invasive beat-to-beat PTT via PES/PCS demonstrated significant correlations with IBP and detected significant changes in SBP(IBP). Thus, PES/PCS as a novel sensor technology may augment intraoperative hemodynamic monitoring during major surgery.