J Extra Corpor Technol 2024 , 56 , 147 – 148 Ó The Author ( s ), published by EDP Sciences , 2024 https :// doi . org / 10.1051 / ject / 2024028
Available online at : ject . edpsciences . org
EDITORIAL
The potential benefits of monitoring oxygen delivery in relation to O 2 ERi and VCO 2 during normothermic regional perfusion in DCD donors
As the field of organ transplantation continues to evolve , the use of Donation after Circulatory Death ( DCD ) donors has emerged as a critical method to expand the donor pool . However , the preservation of organs from DCD donors remains a significant challenge , primarily due to the risk of ischemic damage and subsequent organ dysfunction . Normothermic Regional Perfusion ( NRP ) has been introduced as a technique to mitigate these risks , restoring circulation and oxygenation in the donor organs . Within this context , the monitoring of indexed oxygen delivery ( DO 2i ) about Equilibrium between Required and Supplied Oxygen ( O 2 ERi ) and carbon dioxide production ( VCO 2 ) offers substantial potential benefits that can significantly enhance the outcomes of organ transplantation . Indexed Oxygen delivery ( DO 2i ) plays a pivotal role in ensuring the viability of organs during NRP . Adequate DO 2i is essential to maintain cellular metabolism and prevent ischemic injury during the period between circulatory cessation and organ retrieval . The study by de Somer et al . ( 2011 ) highlights the critical nature of maintaining optimal DO 2i levels during cardiopulmonary bypass , demonstrating that inadequate DO 2i is strongly associated with the development of acute kidney injury ( AKI ) [ 1 ]. This finding underscores the importance of monitoring and maintaining adequate DO 2i levels not only during cardiopulmonary bypass but also in the context of NRP for DCD donors , where organ preservation is paramount . The Equilibrium between Required and Supplied Oxygen ( O 2 ERi ) is a crucial metric that reflects the balance between the oxygen provided to the tissues and the oxygen they actually consume . Maintaining this balance is vital to prevent both under-oxygenation , which can lead to ischemic injury , and over-oxygenation , which can cause oxidative stress and tissue damage . The work by Ranucci et al . ( 2024 ) introduced the concept of a multifactorial dynamic perfusion index that incorporates DO 2i and other perfusion-related variables , demonstrating improved predictive accuracy for AKI when these factors are considered together . In the context of NRP , monitoring O 2 ERiinrelationtoDO 2i could enable more precise control over the oxygenation status of the organs , helping to optimize their viability for transplantation [ 2 ]. A study my group and I published in 2020 showed that hyperlactatemia during CPB , often a sign of inadequate oxygen delivery relative to metabolic demands , can be predicted by monitoring DO 2i in relation to O 2 ERi [ 3 ].
O 2 ERi is a metric used to assess the balance between the oxygen delivered to tissues ( DO 2i ) and the oxygen they consume . It is essentially the oxygen extraction ratio indexed to a patient ’ s body surface area ( BSA ). This balance is critical to prevent both underoxygenation ( leading to ischemia ) and over-oxygenation ( which can cause oxidative stress ).
O 2 ERi can be calculated using the following formula :
O 2 ERi ¼ VO 2i = DO 2i :
Where : VO 2i : The indexed volume of oxygen consumed by the tissues per minute , indexed to BSA . DO 2i : The indexed oxygen delivery , which is the amount of oxygen delivered per minute , indexed to BSA . VO 2i is generally calculated as :
VO 2i ¼ ðArterial Oxygen Content � Venous Oxygen ContentÞ Blood Flow 10 = Body Surface Area : DO 2i is generally calculated as : DO 2i ¼ Blood Flow ðArterial Oxygen Content = Body Surface AreaÞ [ 3 ]
In clinical settings , VO 2 is often approximated using indirect calorimetry or can be calculated if CO 2 production ( VCO 2 ) and respiratory quotients ( RQ ) are known . The relationship between DO 2i and VCO 2 is particularly important during NRP , as it allows for realtime assessment of whether the organs are receiving sufficient oxygen to meet their metabolic needs . Inadequate oxygenation , as reflected by a disproportionate increase in VCO 2 , can be an early indicator of metabolic distress , allowing for timely interventions to adjust perfusion parameters . The integration of DO 2i monitoring with O 2 ERi and VCO 2 during NRP offers several clinical advantages that can significantly improve the outcomes of organ transplantation from DCD donors :
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