Prospective assessment of intraoperative renal perfusion with transit time flow measurements (TTFM) in deceased and living donor kidney transplantation

Optimal graft perfusion is key to achieving satisfactory post-transplant function. The possibility of evaluating vascular flows can lead to the early identification of vascular complications and reflect graft quality and outcome. From 1, 2022 to 1, 2024, transit time flow measurements (TTFM) were prospectively recorded in 75 consecutive kidney transplants (KTx) and analyzed alongside donor, recipient, transplant, and outcome data. Correct measurements were obtained in all cases. Patients receiving living-donor transplants showed higher arterial TTFM (397 (251-532) vs. 295 (167-382) ml/min, p = 0.010) but similar venous TTFM (p = 0.512). Arterial TTFM presented an inverse correlation with donor BMI (r = - 0.241, 95% CI - 0.449-0.008, p = 0.037). Two patients (2.6%) with severely reduced TTFM (< 50 ml/min) developed intraoperative vascular complications and underwent immediate treatment. Patients experiencing delayed graft function (DGF) presented lower arterial and venous TTFM (200 (119-298) vs. 341 (267-448) ml/min, p < 0.001 and 222 (170-391) vs. 369 (272-456) ml/min, p = 0.015), respectively. In patients with higher arterial TTFM, the serum creatinine levels showed a faster decrease (r = - 0.493, 95% CI - 0.652-0.293, p < 0.001). Arterial TTFM (OR: 0.993 (0.989-0.998), p = 0.004) and donor arterial hypertension (OR: 9.292 (2.337-36.935), p = 0.002) resulted in independent risk factors for DGF development at the multivariable logistic regression analysis. The identified arterial cutoff for better outcomes was 310 ml/min (AUROC 0.765). The intraoperative TTFM evaluation in KTx was safe and effective in the early recognition of vascular complications. Arterial TTFM reflect graft quality, with lower flows (< 310 ml/min) correlating with slower post-transplant serum creatinine decrement and representing an independent risk factor for DGF development.