Generation of microbubbles in extracorporeal life support and assessment of new elimination strategies

Abstract

Occurrence of microbubbles (MB) is a major problem during venoarterial extracorporeal life support (ECLS) with partially severe clinical complications. The aim of this study was to establish an in vitro ECLS setup for the generation and detection of MB. Furthermore, we assessed different MB elimination strategies. Patient and ECLS circuit were simulated using reservoirs, a centrifugal pump, a membrane oxygenator, and an occluder (modified roller pump). The system was primed with a glycerin solution of 44%. Three different revolution speeds (2500, 3000, and 3400 rpm) were applied. For MB generation, the inflow line of the pump was either statically or dynamically (15 rpm) occluded. A bubble counter was used for MB detection. The effectiveness of the oxygenator and dynamic bubble traps (DBTs) was evaluated in regard to MB elimination capacities. MB generation was highly dependent on negative pressure at the inflow line. Increasing revolution speeds and restriction of the inflow led to increased MB activity. The significant difference between inflow and outflow MB volume identified the centrifugal pump as a main source. We could show that the oxygenator’s ability to withhold larger MB is limited. The application of one or multiple DBTs leads to a significant reduction in MB count and overall gas volume. The application of DBT can significantly reduce the overall gas volume, especially at high flow rates. Moreover, large MB can effectively be broken down for faster absorption. In general, the incidence of MBs is significantly dependent on pump speed and restriction of the inflow. The centrifugal pump was identified as a major source of MB generation.

Pulsatility protects the endothelial glycocalyx during extracorporeal membrane oxygenation

“…Currently, the standard circuit consists of a membrane oxygenator and a centrifugal pump, through which the non-physiological flow leads to microcirculatory malperfusion. 5,6 Recently, several pumps allowing for pulsatile flow have been developed. 3,7,8 The novel i-Cor system (Xenios AG, Heilbronn, Germany) consists of a diagonal blood pump that provides pulsatility triggered by electrocardiogram and has been applied in Europe for several years.…”

Veno-arterial extracorporeal membrane oxygenation for the treatment of obstructive shock caused by venous air embolism: A case report

“…Second, the rotational speed of ECMO is another concern. Literature review and our own air embolism experiments have shown that low rotational speed can reduce the formation of microbubbles in the return blood[ 8 , 9 ]. In the present case, the initial rotational speed was 2000 rpm, along with the close monitoring of flow volume and bubbles in the circuit.…”

Design and 3D-model of a dynamic bubble trap for cardiopulmonary bypass

“…МП, несмотря на малые размеры, имеют дифференциацию. Некоторые исследователи разделяют пузырьки на: <50 мкм -очень маленькие, к которым относят МП; 50-100 мкм -маленькие; 100-150 мкм -средние; 150-300 мкм -большие; >300 мкм -очень большие [11]. Другие относят к МП все объекты, которые могут измерить текущие системы регистрации в контуре аппаратов ВК (от 5-10 до 250-500 мкм) [12].…”