Efficacy and Safety of Strategies to Preserve Stable Extracorporeal Life Support Flow during Simulated Hypovolemia

Aim:

Without volume-buffering capacity in extracorporeal life support (ELS) systems, hypovolemia can acutely reduce support flow. This study aims at evaluating efficacy and safety of strategies for preserving stable ELS during hypovolemia.Material & METHODS: Flow and/or pressure-guided servo pump control, a reserve-driven control strategy and a volume buffer capacity (VBC) device were evaluated with respect to pump flow, venous line pressure and arterial gaseous microemboli (GME) during simulated normovolemia and hypovolemia.

RESULTS:

Normovolemia resulted in a GME-free pump flow of 3.1±0.0 L/min and a venous line pressure of -10±1 mmHg. Hypovolemia without servo pump control resulted in a GME-loaded flow of 2.3±0.4 L/min with a venous line pressure of -114±52 mmHg. Servo control resulted in an unstable and GME-loaded flow of 1.5±1.2 L/min. With and without servo pump control, the VBC device stabilised flow (SD = 0.2 and 0.0 L/min, respectively) and venous line pressure (SD=51 and 4 mmHg, respectively) with near-absent GME activity. Reserve-driven pump control combined with a VBC device restored a near GME-free flow of 2.7±0.0 L/min with a venous line pressure of -9±0 mmHg.

CONCLUSION:

In contrast to a reserve-driven pump control strategy combined with a VBC device, flow and pressure servo control for ELS show evident deficits in preserving stable and safe ELS flow during hypovolemia.