Is the air handling capability of the quadrox D pump dependent within an ECMO circuit? An in vitro study

Abstract

The occurrence of gaseous microemboli (GME) within the extracorporeal membrane oxygenation circuit is largely overlooked, as are methods to ameliorate this occurrence. We aimed to determine if the air handling capability of the Quadrox D oxygenator was dependent upon whether it was used in conjunction with a centrifugal or roller pump; and if application of a Pall air eliminating filter (AEF) would prevent circuit air introduction from intravenous infusions. Using a blood primed circuit 1 mL of air was infused pre pump. GME were quantified post pump and post oxygenator using the EDAC Quantifier. Trials were conducted at 1 and 2 L/min flow. To prevent GME recirculation a Capiox SX18 was used in circuit with negative pressure applied to its oxygenator; an EDAC cuvette distal to this device quantified GME recirculation. Following air infusion, 3-5 minute data recordings were carried out for each trial. Separate trials were carried out for centrifugal and roller pumps, and for each flow rate. The process was then repeated following the application of the AEF to the air infusion line. More GME were detected post Quadrox D when the centrifugal pump was used in comparison to the roller pump at 1 L/min (p < .05), and 2 L/min (p = .05). A greater volume of air was detected post Quadrox D when used in conjunction with the centrifugal device at 1 L/min (p < or = .05), and 2 L/min (p < or = .05). Application of the AEF resulted in zero GME detected at any circuit location. The results of this study confirm that a greater total count and volume of GME are detected distal to the Quadrox D when used in conjunction with a Rotaflow centrifugal pump. Application of a Pall AEF to infusion and drug lines can prevent air introduction from this source.

Figure 1.

Schematic diagram representing the experimental circuit. HCU, Heater Cooler Unit.

Figure 2.

A comparison of post pump and post Quadrox D total median microemboli count for each pump and flow speed.

Figure 3.

Frequency polygon depicting the median count of detected GME, in 10 micron intervals, post pump and post Quadrox D, following administration of 1 mL of air and when used in conjunction with a centrifugal pump at 1 L/min.

Figure 4.

Frequency polygon depicting the median count of detected GME, in 10 micron intervals, post pump and post Quadrox D, following administration of 1 mL of air and when used in conjunction with a roller pump at 1 L/min.

Figure 5.

Frequency polygon depicting the median count of detected GME, in 10 micron intervals, post pump and post Quadrox D, following administration of 1 mL of air and when used in conjunction with a centrifugal pump at 2 L/min.

Figure 6.

Frequency polygon depicting the median count of detected GME, in 10 micron intervals, post pump and post Quadrox D, following administration of 1 mL of air and when used in conjunction with a roller pump at 2 L/min.