Monitoring of premonitories septic shock in heart-rate variability

Real time monitoring of heart rate variability (HRV) for patients in intensive care unit (ICU) is considered to be useful for predicting their septic shock occurrences. HRV is estimated from a series of heartbeat intervals (RRI). Abnormal heartbeats and very low frequency components in RRI series have to be eliminated carefully because they result in erroneous estimate of HRV. Especially, an effective method of abnormal heartbeat elimination for ICU patients is necessary because ICU patients usually have many arrhythmias. In this study, we propose an abnormal heartbeat elimination method in which a stochastic model concerning with RRI series is employed. Applying the proposed elimination method to RRI series for ICU patients before HRV estimation, we identified a distinctive V-shape temporal pattern in HRV series before septic shock was occurred. The V-shaped pattern is applicable as a signal of septic occurrence. We finally propose a real-time monitoring for sepsis occurrence by using the V-shaped pattern in HRV. It is expected that septic shock occurrence is preventable by presenting an alarm when a V-shaped pattern appears in continuous HRV monitoring.