Introduction: The evaluation of a potential donor patient involves a series of tests and molecular markers to assess the suitability of an organ and the safety for the recipient. A fundamental marker used in out-of-hospital emergency medicine is capnometry, which allows us to indirectly, but accurately, evaluate the potential donor’s organs’ perfusion. These values could help determine the adequacy of a possible donor in an uncontrolled non-heart beating donation (DACD) and donor selection during out-of-hospital medical emergencies. Capnometry values during cardiopulmonary resuscitation (CPR) are a renal transplant evolution predictor in DACD.

Method: Ours is a retrospective study of DACD Maastricht type IIa during a calendar year. The inclusion criteria of the study were: patients who have suffered a witnessed cardiac arrest; age between 16 and 60; asystole electrocardiographic pattern; less than 15 minutes until advanced life support (ALS) arrival; at least 20 minutes of CPR; less than 120 minutes until arrival at the hospital; absence of thorax and abdomen exsanguinating lesions; absence of suspicion of neoplastic, infectious diseases or intravenous drug users (IDUs); chest circumference compatible with chest compression system for donors; and being on hemodialysis and on the renal transplant waiting list for recipients. The data collected from the donors were: age, sex, body mass index, medical history, cause of death, CPR start time, ALS arrival time, time of arrival at the hospital, time of death, cold ischemia and warm ischemia time of each organ, and capnometry values at the begining, at the middle point and at the end of CPR. As from the recipients, collected data were: transplanted organ, cause of chronic kidney disease (CKD), starting date of dialysis, number and type of transplant incompatibilities, renal failure, acute rejection, number of dialysis sessions after transplant, urologic complications, transplant-related infections, serum creatinine levels on 1st, 7th, 15th, 30th, 90th, 180th and 360th days after transplant, levels of proteinuria on 1st, 7th, 15th, 30th, 90th, 180th and 360th days after transplant, one-year transplanted organ survival, one-year recipient patient survival. The quantitative variables are summarized with their median and interquartile range (IR), and the qualitative variables are presented with their distribution of absolute (n) and relative (%) frequencies. We evaluated the correlation between capnometry values of the donor (at the beginning and at the middle point of CPR, and during hospital transference) with creatinine and proteinuria levels on the specified days using the Spearman correlation test. The association between qualitative variables with the capnometry values was evaluated with the Wilcoxon test. For all these tests, a p <0.05 was the accepted level of statistical significance.

Results: During a calendar year, 34 donors were studied. The mean age of the donors was 46.9 years, and 82.4% of them were male. The median capnometry value was: 21.3 +/- 12 at the beginning of CPR, 27.4 +/- 12.2 at the middle point of CPR, and 23 +/- 11.7 during hospital transference. The analysis of the correlation between at-the-middle-point-of-CPR and hospital-transference capnometry values, and creatinine and proteinuria levels, showed a statistically significant moderate-to-high negative correlation. Also, a statistically significant association was observed between hospital-transference capnometry values and the number of after-transplant dialysis sessions the receptor needed.

Conclusion: Capnometry is a useful tool to determine kidney transplant viability and prognosis. There is an association between donors capnometry values at the middle point of CPR and during hospital transference, and creatinine and proteinuria levels of the recipient, and another association between high capnometry values during hospital transference and a less need of after-transplant dialysis.