In vitro and in vivo test of a customized system for extracorporeal life support

Objective We tried to develop a reliable, stable and effective customized ECLS system through a well designed in vitro and in vivo study. Methods An in vitro test model of the ECLS system, mainly consisting of a pseudo-patient (a blood reservoir), bladder, oxygenator, pump tube (outer diameter: 1/4 inch), roller pump and the heater, was built. Performances of the pump, monitors, and the heater were observed every day. The precision of the pump flow (pressure monitor or the heater) was compared with a transonic flow-meter (Medtronic ECMO system or thermometer). The monitors were tested to see if they could meet the requirements. Four healthy and two mild ARDS piglets were supported with the customized ECLS system for 24 hours. Hemodynamics, lung mechanics, gas change and hematological parameters of the piglets and performances of the machine were recorded. Agreement between the customized ECLS system and other devices including the transonic flow-meter, Medtronic ECMO system and thermometer was evaluated by the Bland-Altman method. Results The pump, the monitors, and the heater functioned well without accidently stopping working. The 95% limits of agreement of pump flow, pre-pump pressure, post-pump pressure, post-membrane pressure, and temperature were (-0.04 L/min, 0.03 L/min), (-3 mmHg, 3 mmHg), (-5 mmHg, 6 mmHg), (-6 mmHg, 6 mmHg), (0.1 ℃, 0.3 ℃). The pressure monitors and the bladder could alarm and stop the pump fast during a 100 times trail. The bubble detector could respond well (alarm and stop the pump) to 60 of the 100 bubbles injected into the circuit. The alarming temperature of the heater was (42.3±0.2)℃. The customized ECLS worked well without complications throughout the in vivo test. A temporary decrease of Cdyn and increase of A-aDO2 and OI were observed in healthy piglets while an escalating trend of Cdyn and a downtrend of A-aDO2 and OI in ARDS piglets. Mean arterial blood pressure of the piglets supported with the customized ECLS system maintained stable while the Hb and PLT decreased. Conclusion In vitro and in vivo test showed the pump, pressure monitors and the heater of the customized ECLS system functioned well, and the feasibility, safety and stability of the system were preliminarily verified from the cytosol of the cell to the lumen of the sarcoplasmic reticulum. Key words: Extracorporeal life support; Customized; In vitro; In vivo; Agreement