Flow-Bubble Sensors For Heart-Lung Machines

Bubble Sensors Guarantee Patient Protection

Bubble detectors are key to patient safety. They are required to be clamped on the arterial line right after the arterial filter to protect against massive air embolism. The bubble sensors automatically warn and deactivate the arterial pump. However, there are further options to place bubble detectors within the HLM circuit. The venous reservoir represents the first critical position where air can get into the circuit. Therefore, a reasonable location to apply the bubble sensor is between the venous reservoir and the arterial pump. Even to place a bubble sensor between the oxygenator and arterial line filter allows for trapping and purging air if necessary. The ideal and safest set-up would be to have multiple bubble sensors.

Pressure Sensors

Pressure sensors continuously measure and document the pressure within the tubing system. If certain pressure limits are reached, an alarm signal is triggered. This ensures that the HLM does not pump the blood back into the patient's vascular system at too high a pressure.

Pump Monitoring With Flow Sensors

Flow sensors are also a main component in HLM’s. In order to not only detect air bubbles but also to effectively manage them, using shunts to connect the arterial circuit line and the venous reservoir in the tubing set-up is a critical point. When air is detected, the arterial line is promptly closed by the arterio-venous shunt while the detected air is directly eliminated to the venous reservoir. When no more air is spotted, the shunt automatically re-opens the tubing to again feed the arterial line going straight into the human body. For this reason, flow rates passing the shunt need to be continuously compared to the flows generated by the arterial pump, monitored and controlled over the time the HLM is running. Ultrasonic flow meters accomplish this task failure-free and reliably.

Level Sensors

Level sensors are utilized to monitor changes in fluid or blood volume in the venous reservoir of the heart-lung machine.

Top medtech companies already rely on this game-changing technology and have implemented the control and monitoring unit for instantaneous flow and bubble detection into their equipment. One of the industry‘s leading companies developing and manufacturing HLMs has integrated the hybrid sensor solution into its recently launched device.

The main reason for the manufacturer to trust in the SONOFLOW CO.56 Pro sensor series is the small electronic footprint and the option for multipoint measurement: Five of the smart sensors with different tubing channels have been applied to the customer‘s newly developed console. The onboard electronics and its options for data processing make connecting the sensors an easy game. The built-in microcontroller guarantees to control all processes while data is transferred via the RS485-interface. The sensors themselves measure flow rates on different tubes and shunts leading to the body or back into the venous circuit of the heart-lungmachine. Simultaneously, they detect air bubbles accidentally caused. Finally, the non-invasive ultrasonic sensors give feedback on the real flow compared to the theoretical flow of the pump.