Measurement of dynamic vein pressure during venous needle dislodgement

Venous needle dislodgment during dialysis treatment significantly reduces patients' QOL and can occasionally result in mortality. Therefore, a method of detecting needle dislodgement by monitoring pressure at the venous side (blood return side) during treatment is required. However, some reports have questioned the validity of performing pressure-based monitoring. In this study, we created an experimental circuit using blood circuit, pressure pump, and indwelling needle. Then, we conducted an experiment simulating the intra-access pressure of the patient. This experiment examines the amount of pressure change that occurs when the needle is pulled out. In the experiments, the intra-access pressure was 0, 50, 100, or 200 mmHg, and the pressure change when the needle was removed from the hemodialysis circuit under each condition was measured over time. The results showed a strong positive correlation between the simulated intravascular pressure and the pressure difference at the time of needle removal, and pressure-based monitoring was considered to be difficult unless the intravascular pressure was ≥50 mmHg. However, in a previous study, the internal pressure of the arteriovenous fistula (AVF), which is often used for vascular access, was 32.6 ± 23.5 mmHg. As such, because many Japanese hemodialysis patients have AVF (89.7%), pressure-based monitoring may often be ineffective. Therefore, when needle dislodgment is monitored using pressure, measures other than using a method in which the intravascular pressure is intentionally increased by tightening the tourniquet at the upper arm and other than by pressure monitoring should be taken.