Impact of Volume Control Biosensors on Blood Pressure During Haemodialysis: A Quasi-Experimental Study

Background: Intradialytic hypotension is a common complication in haemodialysis, affecting up to 30% of sessions. It results from an imbalance between ultrafiltration and compensatory mechanisms, such as vascular tone and plasma refilling. Volume-controlled biosensors allow for the continuous monitoring of the haemoconcentration, enabling early detection and prevention of hypotension. Methods: A quasi-experimental study was conducted to assess the effectiveness of biosensors in reducing hypotensive episodes. Two biosensors were compared: the Blood Volume Monitor and the Haemomaster system. Data were collected over two four-month periods: before and after biosensor implementation. Nursing staff received specific training, and a protocol for consistent data collection was established. Informed consent was obtained from all eligible participants. The incidence of intradialytic hypotension was compared between sessions with and without biosensor use. Additionally, outcomes were analysed according to biosensor type. Results: A total of 2262 dialysis sessions from 22 patients were analysed. The cohort was 54.5% male, with a mean age of 60 years (SE = 21); 27.3% had diabetes and 81.8% had hypertension. Post-dilution haemodiafiltration was performed in 62.8% of sessions. Intradialysis hypotension occurred in 11.2% of sessions using biosensors compared to 14.0% without (p = 0.021). No significant difference was found between biosensor types (10.8% vs. 11.8%; p = 0.531), although device 1 reached a significantly lower critical blood volume (mean: 10 L; SE = 4 vs. 16 L; SE = 5; p = 0.000). Conclusions: Biosensor use was associated with fewer hypotensive episodes and greater haemodynamic stability. These findings support their integration into routine dialysis practice to improve treatment, safety, and individualised care.