Objective: Warm ischemic time (WIT) is one of the risk factors for rejection and loss of renal function in renal transplantation. Anastomosis of the renal artery and vein of a transplant recipient without cooling maneuvers exposes the kidney to temperatures above the metabolic threshold. This anastomosis time, or second warm ischemic time (SWIT), can adversely affect graft outcome, especially if prolonged. In 2022, an insulated gel bag for renal transplantation, OrganPocket® (SCREEN Holdings Co.,Ltd. Japan), was launched on the market. We experienced a group of 13 patients who underwent living renal transplantation using the OrganPocket® at our hospital (OP group: 13 cases) and analyzed the temperature change during the second warm ischemic time  by thermography. We also compared the temperature change and postoperative results with those of the group that underwent living renal transplantation without the OrganPocket® (control group: 13 cases).
Methods: OP group recipients: median age 46 years old (5 males, 8 females), BMI 21.7, donor age 51 years old (5 males, 8 females); Control (Ctrl) group recipients: median age 43 years old (7 males, 6 females), BMI 22.6, donor age 61 years old (4 males, 9 females). Temperature changes over time were measured with thermography from the time of kidney graft cooling until resumption of blood flow after anastomosis. During secondary warm blood ischemic time in the Ctrl group, the renal graft was directly cooled with a cooled lactate Ringer's solution intermittently for surface cooling. Surface temperature while wearing the OrganPocket®  was targeted to the renal hilus.
Results: Ischemic time was 3 min WIT, 19 min cold ischemic time (CIT), and SWIT 52 min for the OP group. In the Ctrl group, WIT was 3 minutes, CIT 20.5 minutes, and SWIT 49 minutes. renal temperature after core cooling was 6.1℃ for the OP group and 8.3℃ for the Ctrl group. At 5, 10, 15, and 20 minutes after the start of anastomosis, the temperatures were 16.5℃, 17.6℃ 19.7℃, and 21.0℃ in the OP group and 12.1℃, 13.6℃, 13.6℃, and 16.5℃ in the Ctrl group, respectively. Before resumption of blood flow by clamp release, the renal surface after removal of the organ pocket in the OP group was 19.5℃ and the difference from the ambient operative field temperature (29.6℃) at that time was 10.1℃. The difference between the renal and ambient operative field temperature before resumption of blood flow in the Ctrl group was 10.6℃. Postoperative renal function was good, with intraoperative urination onset in all patients and no cases of delayed graft function.
Conclusion: The use of OrganPocket® made it possible to maintain the renal graft at a low temperature during anastomosis.