Changes in Central Venous Oxygen Saturation during Inpatient Hemodialysis.

INTRODUCTION

Ultrafiltration during hemodialysis can precipitate intradialytic hypotension (IDH), particularly in hospitalized patients with limited cardiovascular reserves. Central venous oxygen saturation (ScvO2) is a surrogate marker of cardiac output and may provide real-time insights into hemodynamic stress during dialysis.

METHODS

We analyzed data from a prospective observational study of hospitalized adults receiving intermittent hemodialysis with central venous catheters for either acute kidney injury (AKI) or end-stage kidney disease. Continuous ScvO2 was measured throughout the dialysis sessions using Crit-Line-IV. Mixed-effects models were used to characterize intradialytic ScvO2 trends, with restricted cubic splines to evaluate the associations between ScvO2 slopes, ultrafiltration rate (UFR), and IDH.

RESULTS

During 204 hemodialysis sessions among 135 individual participants, ScvO2 declined during 58% of the sessions, with substantial inter-patient variability in ScvO2 slopes. Steeper negative ScvO2 slopes were associated with a higher risk of IDH across all IDH definitions, particularly among patients with AKI. Hemodialysis sessions with the steepest ScvO2 declines (defined as the bottom 25th) were associated with increased risk of requiring an intervention for hemodynamic instability, independent of UFR and pre-dialysis blood pressure (adjusted OR: 2.42, 95% CI: 1.12, 5.20). This association was enhanced in patients with AKI (adjusted OR: 5.80, 95% CI: 2.05, 16.46).

CONCLUSIONS

Continuous intradialytic ScvO2 monitoring is feasible in hospitalized patients and may identify patients at higher risk of hemodynamic instability, especially among those with AKI. ScvO2 may be a useful adjunct for guiding ultrafiltration during inpatient hemodialysis.