Capnometry predicts the viability of procured kidneys from uncontrolled donation after circulatory death donors

Although uncontrolled donation after circulatory death (uDCD) donors provide kidney transplants with excellent long-term survival rates, a significant percentage of grafts are eventually found not to be viable for transplantation. Capnometry during cardiopulmonary resuscitation (CPR) is a marker of tissue metabolism and organ perfusion. We analyzed whether capnometry values in potential uDCD donors could help to differentiate between valid (who provided at least one transplantable kidney) and futile uDCD donors (those not yielding suitable grafts for transplantation).

This study was performed at two transplant centers between January 2018 and December 2023. Patients who had unsuccessful out-of-hospital CPR attempt after cardiopulmonary arrest (CPA) and met the criteria for uDCD were selected. Capnometry values were analyzed at the start of CPR, at the midpoint and at arrival at the hospital (transfer), along with other prehospital variables that could influence the selection of a viable donor.

Overall, 69 potential uDCD donors were included, of which 26 (37.7 %) were valid and 43 (62.3 %) were futile. The capnometry values in valid donors compared to futile donors were 24.5 mmHg versus 16 mmHg at the initial reading (P-value <0.078) and 26 mmHg versus 15 mmHg at transfer, respectively (P-value <0.004). The optimal cut-off value for transfer capnometry levels to discriminate viable from futile donors was 17 mmHg. In the multivariable model, mechanical chest compression (odds ratio [OR]: 14.29; P-value = 0.009), transient return of pulse (OR: 19.0; P-value = 0.013), donor age (OR [per one-year increase]: 0.91; P-value = 0.026) and capnometry values at arrival at hospital (OR [per one-mmHg increase]: 1.08, P-value = 0.012) were independent predictors of donor viability.

Capnometry obtained at hospital arrival is useful for identifying valid uDCD donors. In addition, younger donor age, use of mechanical chest compression devices, and transient return of pulse are prehospital variables that also increase the odds of viability in this type of donors.