Real-Time Tissue Oxygenation Monitoring Using Fiberoptic Sensors in Cadaveric Multiorgan Preservation under Mouse ECMO

Background: Organ shortage has become a global challenge for the treatment of end-stage organ failure accounting on average 15 to 30% of patients dying annually on a waiting list. The biggest challenge remains the extending of organ's shelf life. Extracorporeal membrane oxygenation (ECMO) has shown great promises both in vivo and ex vivo. Some clinical data suggest using ECMO for multiorgan recovery from nonheart beating and brain-dead donors. In this regard, our robust mouse ECMO model offers unprecedented platform for optimizing protocols toward cadaver organ procurement for transplantation purposes. As we use both blood-mixed and bloodless perfusion protocol, the versatile measurement of tissue oxygenation is essential to monitor quality of organ storage and reperfusion. The aim of the study was to monitor in real-time mode partial pressure of oxygen (pO₂) in different organs of mouse cadavers subjected to venoarterial ECMO

Method: Pooled C57Bl/6 mice (aged 16–18 weeks with an average weight of 27 ± 1 g) directly after sacrificing were administered with 500 U streptokinase/500 U heparin and reanimated for 5 minutes by gentle closed-chest cardiac massage. An ECMO circuit was primed with 0.6 mL of 1:1 mixture of Krebs-Henseleit solution (containing 2.25 mM CaCl2) and 6% hydroxyethylstarch solution. ECMO was initiated in 1.5 hours after death. Experimental animals were run on ECMO device for 2 hours at 22 to 24°C, whereas control animals did not undergo any treatments apart from heparinization. The pO₂ was measured intramuscularly and intraorgan using a needle fiberoptic sensor connected to a portable monitoring device.

Results: Directly after the death, the pO₂ values did not exceed 5 mm Hg in all cadaver mice. In the mice not subjected to ECMO, those values did not change with time as opposed to ECMO groups (both blood-mixed and bloodless) where they increased dramatically at least in the range of 60 to 100 mm Hg within the first minutes of oxygenated perfusion and remained stable in the course of perfusion. Notably, after 2 hours of ECMO cadaver mice presented active heart beating. As a separate highlight, significantly higher intraorgan pO₂ levels (liver, intestine, and heart) were detected for ECMO mice compared with controls.

Conclusion: In this study, for the first time, we report an experimental proof of principle for the real-time measurement of tissue pO₂ using needle sensor in ECMO-assisted cadaver mice for optimizing postmortem organ recovery.

Publication History

Article published online:
03 February 2022