Beyond rewarming time: graft thermometry and cooling technologies in robot-assisted kidney transplantation—a scoping review

Abstract

Robot-assisted kidney transplantation (RAKT) converts vascular anastomosis time into an incompletely measured thermal exposure. We mapped how grafts are cooled and how temperature is measured, reported, and linked to outcomes during RAKT. Following a prespecified protocol and a documented search-source amendment, PubMed/MEDLINE, Scopus, and Web of Science Core Collection were searched from inception to 26 July 2026; a backward and forward citation-chain audit was completed on 2 August 2026. Human or large-animal RAKT reports were eligible if they provided numeric intraoperative graft or pelvic thermometry or evaluated a purpose-built cooling system. Data were charted by report and innovation program. Clinical, technical, and measurement heterogeneity precluded meta-analysis. Reporting followed PRISMA-ScR. Seven reports from six innovation programs met eligibility criteria: five human studies, one porcine study, and one mixed bench-porcine-human development study. Six reports contained numeric graft or pelvic thermometry; one mesh-wrap report specified a target below 15 °C but did not measure graft temperature. Among continuous-cooling RAKT groups reporting mean ± SD thermometry, values ranged from 6.5 ± 3.1 °C at reperfusion in pigs to 19.74 ± 1.61 °C at 65 min in a matched human cohort; regional ice-based clinical series reported mean pre-reperfusion surface temperatures of 20.1-22.5 °C. Only two reports explicitly specified both a precise anatomical measurement site and a sampling interval.No study validated a clinically actionable threshold or an adjusted temperature-outcome relationship. Observed thermometry in six reports demonstrates that hypothermic conditions can be achieved under specific cooled RAKT protocols, but evidence of target attainment does not extend to the device-intent-only report and comparative clinical effectiveness remains unproven. Elapsed rewarming time should not substitute for graft thermal exposure. Standardized sensor metadata, serial temperatures, and temperature-dose metrics are prerequisites for comparative trials.