Arterial Blood Pressure Waveform in Liver Transplant Surgery Possesses Variability of Morphology Reflecting Recipients' Acuity and Predicting Short Term Outcomes

Weinvestigated clinical information underneath the beat-to-beat fluctuation of thearterial blood pressure (ABP) waveform morphology. We proposed the DynamicalDiffusion Map algorithm (DDMap) to quantify the variability of morphology. The underlying physiology could be thecompensatory mechanisms involving complex interactions between variousphysiological mechanisms to regulate the cardiovascular system. As a livertransplant surgery contains distinct periods, we investigated its clinical behaviorin different surgical steps. Our study used DDmap algorithm, based onunsupervised manifold learning, to obtain a quantitative index for the beat-to-beatvariability of morphology. We examined the correlation between the variabilityof ABP morphology and disease acuity as indicated by Model for End-Stage LiverDisease (MELD) scores, the postoperative laboratory data, and 4 early allograftfailure (EAF) scores. Among the 85 enrolled patients, the variability ofmorphology obtained during the presurgical phase was best correlated with MELD-Nascores. The neohepatic phase variability of morphology was associated with EAFscores as well as postoperative bilirubin levels, international normalizedratio, aspartate aminotransferase levels, and platelet count. Furthermore, variabilityof morphology presents more associations with the above clinical conditionsthan the common BP measures and their BP variability indices. The variabilityof morphology obtained during the presurgical phase is indicative of patientacuity, whereas those during the neohepatic phase are indicative of short-termsurgical outcomes.