In-vitro quantification of gaseous microemboli in two extracorporeal life support circuits

Abstract

During the course of extracorporeal membrane oxygenation, patients are at constant risk of exposure to air emboli. Air emboli may enter the circuit during routine lab sampling, medication administration, air entrainment through the venous cannula, or via a circuit disruption. Circuit components have been designed and positioned to minimize the quantity of air that travels through the arterial line to the patient. The purpose of this study was to assess the air handling of a newer generation extracorporeal life support circuit. The extracorporeal life support circuit consisted of an open hard-shell venous reservoir, Better Bladder (BB14) or silicone bladder (R-14), and Quadrox D oxygenator or 0800 silicone oxygenator. Air emboli detection sensors were placed in the extracorporeal life support circuit: post bladder, post oxygenator, and post heat exchanger if applicable.Air was injected as a 1 mL/min for 5 minutes injection or as a single 5 mL bolus. Emboli detection was recorded continuously during and for 3 minutes post air injection at two blood flow rates (Qb) (.5 and 1.2 L/min). All tests were performed in triplicate with each condition. All tested components reduced the embolic volume transmitted through the circuit. The quantity of this reduction was dependent on both the Qb and the air injection condition. During this in-vitro testing, air emboli passing through any of the components tested was decreased. Furthermore, the emboli delivery was reduced post component with the slower Qb (.5 L/min).

Figure 1.

Diagram of circuit A, Quadrox D® and Better Bladder.

Figure 2.

Diagram of circuit B, Silicone 0800 oxygenator, ECMOtherm heat exchanger, and silicone bladder.

Figure 3.

Comparison of the silicone bladder (R-14) to the better bladder (BB14) at Q_b .5 L/min with both a 1 mL/min × 5 minutes air injection (A_S) (R-14 = .0001 (±.0001)), (BB14 = .0018 (±.002)) and 5 mL air bolus (A_B) (R-14 = .0005 (±.0006)), (BB14 = .011 (±.014)). GME volume is total measured during trial time.

Figure 4.

Comparison of the silicone bladder (R-14) to the better bladder (BB14) at Q_b 1.2 L/min with both a 1 mL/min × 5 minutes air injection (R-14 = .007 (±.0006)), (BB14 = .057 (±.029))*(p < .05) (A_S) and 5 mL air bolus (R-14 = .002 (±.0003)), (BB14 = .053 (±.017))*(p < .05)(A_B). GME volume is total measured during trial time.

Figure 5.

Comparison of the Quadrox D® (QD) to the 0800 silicone oxygenator (0800) alone at Q_b .5 L/min with both a 1 mL/min × 5 minutes air injection (A_S) (QD = .00001 (±.000008)), (0800 =.00016 (±.00013)) and 5 mL air bolus (A_B) (QD = .00032 (±.00028)), (0800 = .00010 (±.00015)). GME volume is total measured during trial time.

Figure 6.

Comparison of the Quadrox D ® (QD) to the 0800 silicone oxygenator (0800) alone at Q_b 1.2 L/min with both a 1 mL/min × 5 minutes air injection (A_S) (QD = .00072 (±.00009)), (0800 = .069 (±.037)) *(p < .05) and 5 mL air bolus (A_B) (QD = .0012 (±.0011)), (0800 = .117 (±.062)). GME volume is total measured during trial time.

Figure 7.

Comparison of the Quadrox D® (Circuit A) to the 0800 silicone oxygenator and separate ECMOtherm heat exchanger (Circuit B) at Q_b .5 L/min with both a 1 mL/min × 5 minutes air injection (A_S) (Circuit A = .00001 (±.000008)), (Circuit B = .000006 (±.000003)) and 5 mL air bolus (A_B) (Circuit A = .00032 (±.00028)), (Circuit B = .00014 (±.000006)). GME volume is total measured during trial time.

Figure 8.

Comparison of the Quadrox D ® (Circuit A) to the 0800 silicone oxygenator and separate ECMOtherm heat exchanger (Circuit B) at Q_b 1.2 L/min with both a 1 mL/min × 5 minutes air injection (Circuit A = .00072 (±.00009)), (Circuit B = .0036 (±.0043)) *(p < .05)(A_S) and 5 mL air bolus (Circuit A = .0012 (±.0011)), (Circuit B = .013 (±.0057))*(p < .05)(A_B). GME volume is total measured during trial time.