Pleth Variability Index Changes useful Predictor of Intradialytic Hypotension, finds study

A new research published in the journal of BMC Nephrology showed that Dynamic changes in Pleth Variability Index (PVi) during the first hour of hemodialysis independently and strongly predict the risk of subsequent intradialytic hypotension (IDH). Continuous PVi monitoring provides a practical, non-invasive method for early risk stratification and timely intervention.

IDH affects nearly one in three patients and can lead to dizziness, organ damage, and increased mortality risk. Despite its frequency, physicians have long struggled with reliable early prediction methods. Traditional indicators such as the baseline blood pressure or fluid removal volume have offered only limited accuracy.

The focus now is shifting to the Pleth Variability Index, which is a non-invasive parameter derived from pulse oximetry that reflects fluid responsiveness and cardiorespiratory interactions. While PVi has been used in critical care settings, its role in routine hemodialysis has remained largely unexplored, until now.

This prospective observational study involved 200 chronic hemodialysis patients across multiple centers, and monitored PVi at the start of dialysis and again one hour into the session. This focused particularly on how PVi changed over time, by calculating both absolute and percentage variations.

IDH occurred in 30.5% of participants, and while baseline PVi values showed no meaningful difference between those who developed IDH and those who did not, the dynamic changes told a different story. The patients who experienced IDH had significantly higher PVi readings after one hour, as well as larger increases overall.

A threshold increase of just over 23% was associated with a strong ability to predict IDH, which offered nearly 79% sensitivity and 75% specificity. The patients exceeding this threshold were found to have more than 7-times the risk of developing IDH when compared to others.

These dynamic PVi measures significantly outperformed conventional predictors. Statistical analysis confirmed that both absolute and percentage changes in PVi were independent and robust predictors of IDH, even when accounting for other clinical variables. Since PVi monitoring is non-invasive and easy to implement, it offers a practical way for clinicians to identify high-risk patients early and adjust therapy before complications arise.

Overall, real-time tracking of physiological changes could help prevent dangerous drops in blood pressure and improve patient outcomes during dialysis. Further dedicated research is required to integrate PVi monitoring into routine clinical protocols.

Reference:

Li, J., Xu, Q., Li, F., Yang, T., Gao, C., Li, Y., Zhou, J., Cao, Y., Tong, C., Lu, W., & Wu, Y. (2026). The value of pleth variability index in predicting hypotension during maintenance hemodialysis: a prospective observational multicenter study (PVi-HD study). BMC Nephrology. https://doi.org/10.1186/s12882-026-04883-4