Automated therapeutic anticoagulation: A closed-loop approach using a modified measurement device

Measurement of the activated clotting time (ACT) is an important and regularly performed task in hospitals for thrombosis prevention. Required adjustments of anticoagulation therapy are most often done manually by using a therapeutic look-up table adapted to patient weight. This process is prone to human errors and an automated solution for calculating the required change and readjusting the individual infusion rate of an anticoagulant therefore would provide benefits. Currently no automated blood anticoagulation system is available and we thus decided to expand an existing ACT measurement device with real-time reporting capabilities. We intercepted the electrical signals to the device's seven segment displays and converted the electrical signals of the numbers using a Raspberry Pi. Then an automated closed-loop heparinization following a look-up table approach as used in clinical practice was implemented. To prove the feasibility of the system, a successful test for 96 hours in an anaesthetized animal was performed. While this study has shown that automatic closed-loop adaptation in a medical environment is feasible, we discuss possible implications of this approach, outline open problems and address issues that need to be solved towards a more automated and better medical care in general.