Abstract

Background Renal resistance (RR) measured during hypothermic machine perfusion (HMP) is used to assess donor kidney quality and guide transplantation decisions. However, its clinical reliability and relationship with donor factors remain unclear.

Methods This scoping review and meta-analysis evaluate the variability, determinants, and predictive value of RR during HMP. A systematic search of PubMed, Embase, Web of Science, and Cochrane Library (July 2024) identified 49 primary studies reporting RR in perfused human kidneys. The risk of bias was assessed using the ROBINS-I tool. Meta-analyses for the predictive value of RR were performed when ≥3 studies reported univariable associations for the same time point and outcome.

Results Most studies had moderate to serious risk of bias. RR typically declined rapidly, stabilizing within 5 hours (range: 0.30–3.50 to 0.17–1.50 mmHg/mL/min), but patterns varied widely. Determinants included histology, donor characteristics, and perfusion additives, though evidence was inconsistent. A meta-analysis showed terminal RR was significantly associated with delayed graft function (odds ratio 2.49, 95% CI 1.49-4.18, I2=58%). While several studies proposed RR-thresholds, none were consistently validated, and heterogeneity in measurement timings and device settings limits comparability.

Conclusion RR shows potential as a functional assessment parameter during HMP but is influenced by multiple technical and biological factors. Current evidence does not support the use of isolated RR-thresholds for organ acceptance. Standardized HMP protocols, trajectory modeling, and prospective studies are needed to clarify RR’s role in clinical decision-making.

Funding This study was funded by a grant from the KU Leuven Research Council (C2M/23/051) and was preregistered at the Open Science Framework (DOI: 10.17605/OSF.IO/D8QYU).

Competing Interest Statement

IJ received an unrestricted research grant from XVIVO Perfusion paid to her institution.

Funding Statement

This study was funded by a grant from the KU Leuven Research Council (C2M/23/051) and was preregistered at the Open Science Framework (DOI: 10.17605/OSF.IO/D8QYU).

Author Declarations

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I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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Data Availability

All data that support the findings of this study are openly available in RDR, the KU Leuvens repository at https://doi.org/10.48804/YG4LXD

AbbreviationsAHabnormal histologyAPanterograde perfusionAUCarea under the curveBMIbody mass indexCIconfidence intervalCITcold ischemia timeDBDdonation after brain deathDCDdonation after circulatory deathDGFdelayed graft functionDKTdouble kidney transplantationDORdiagnostic odds ratioECDexpanded criteria donorseGFRestimated glomerular filtration rateENOS-nitrosylating agent ethyl nitriteFdegrees of freedomGFRglomerular filtration rateGPgood perfusionHLAhuman leukocyte antigenHRhazard ratioHTKhistidine-tryptophane-ketoglutarateIFimmediate functionIFNarterial intimal fibrous narrowingIGLInstitut Georges LopezIVinverse varianceKDPIkidney donor profile indexKDRIkidney donor risk indexMDRDmodificaton of diet in renal diseaseMPmarginal perfusionNGnot givenNHnormal histologyNRPnormothermic regional perfusionORodds ratioPGE1prostaglandin-1PNFprimary non functionRcorrelation coefficientROCreceiver operating characteristicRPretrograde perfusionRRrenal resistanceSEstandard errorSKTsingle kidney transplantationTIStubular interstitial scarringtPAtissue plasminogen activatorUWUniversity of Wisconsinyyear