A retrospective review of 75 abdominal NRP procedures compared intra-abdominal with descending thoracic cannulation. Thoracic access was associated with shorter cannulation time, higher circuit flows, and fewer red-cell transfusions. Larger lactate changes occurred during longer perfusion runs, but duration-normalized values were similar. Selection bias and concurrent thoracic organ recovery limit interpretation; organ utilization and recipient outcomes were not available.
Abdominal normothermic regional perfusion, or A-NRP, restores oxygenated blood flow to abdominal organs after donation following circulatory death. The objective is to support organ assessment and recovery under warm, blood-based perfusion conditions. Cannulation is an important part of that process, because access, venous drainage, blood loss, and the ability to establish adequate circuit flow all influence the conduct of perfusion. In this retrospective study, Boyne and colleagues compared their established intra-abdominal approach with a newer descending thoracic aortic approach. The findings suggest another practical option for experienced teams, but they do not establish that one technique improves transplant recipient outcomes.
The investigators reviewed all A-NRP procedures performed by Regional Perfusion Services between July 1, 2024, and June 30, 2025. The analysis included 75 cases: 28 used intra-abdominal cannulation, designated IA-NRP, and 47 used descending thoracic cannulation, designated DT-NRP. Sixteen surgeons and five perfusionists participated in at least one procedure. This was an observational comparison within one service, rather than a randomized trial. Technique selection therefore reflected clinical and procurement circumstances, leaving important differences between the groups that could influence the results independently of cannulation.
The distinction between access site and perfused territory is central to interpreting the paper. DT-NRP uses the descending thoracic aorta for arterial access and the right atrium for venous drainage, but the intended perfusion territory remains abdominal. The authors describe proximal aortic exclusion and venting to prevent cerebral and thoracic perfusion. This should not be confused with thoracoabdominal NRP intended to support thoracic organs. Their intra-abdominal approach instead establishes access near the abdominal aortic bifurcation and adjacent inferior vena cava. These descriptions explain the study comparison; they are not a substitute for institutional procurement protocols, surgical training, or verification of regional exclusion.
One motivation for the descending thoracic approach was the difficulty of abdominal vascular access in certain donors. Previous abdominal surgery, obesity, and distal aortic atherosclerosis may complicate intra-abdominal cannulation. The authors propose that thoracic access can avoid some of these obstacles and permit a more direct route for venous drainage. However, thoracic access has its own limitations. They state that DT-NRP is not indicated in a redo chest and may be challenging when left-sided thoracic scarring follows infection or prior instrumentation. The useful clinical message is flexibility in access selection, rather than a universal preferred route.
Median cannulation time was 8.5 minutes with DT-NRP and 10.0 minutes with IA-NRP, with a reported P value of 0.016. The absolute difference was 1.5 minutes, equivalent to a 15% lower median compared with the intra-abdominal group. That is a potentially relevant operational improvement, but the data should not be interpreted as a guaranteed time saving for every donor. The authors attribute the difference partly to working within one cavity and to the accessibility of the descending aorta and right atrial drainage. Differences in anatomy, surgeon experience, and procurement requirements remain plausible contributors.
Perfusion duration moved in the opposite direction. Median NRP time was 91.0 minutes in the descending thoracic group and 61.5 minutes in the intra-abdominal group, with P = 0.006. Longer time on perfusion was not a predefined treatment target or proof of improved preservation. Duration was influenced by surgical preferences, logistics, and pump stability. Intra-abdominal cases more often involved concurrent rapid recovery of thoracic organs, which could shorten the available perfusion period. Comparing total duration without considering that procurement context would therefore oversimplify the findings.
The transfusion difference was substantial: median packed red blood cell use was zero units in DT-NRP and three units in IA-NRP, with P < 0.001. The authors also observed higher peak and lowest circuit flows with the descending thoracic approach, despite similar calculated target flows. Ratios of observed flow to target favored DT-NRP. These findings are consistent with the proposed benefits of improved drainage and less volume loss, but the study cannot isolate which mechanism produced the observed differences. Cannulation site, procurement activity, blood collection for other systems, and surgical dissection could all contribute.
Thoracic organ recovery is a particularly important confounder. Sixteen IA-NRP cases included rapid recovery of the heart, lungs, or both. Four heart recoveries used the Organ Care System, requiring blood removal for circuit priming. Only two lung rapid recoveries were reported in the DT-NRP cohort. Loss of blood and volume during thoracic dissection, together with blood diverted for another preservation system, could increase transfusion requirements and disturb regional perfusion. The paper explicitly recognizes that the groups were not directly comparable on this dimension. The transfusion result is therefore an association, not evidence that changing arterial access alone will eliminate transfusion.
Lactate interpretation requires similar care. The median reported lactate change was 2.9 mmol/L in DT-NRP compared with 2.3 mmol/L in IA-NRP, with P = 0.024. A larger decrease could reflect perfusion conditions, additional time for metabolic recovery, or differences in blood entering the circuit. The investigators also calculated an exploratory duration-normalized lactate range. That measure was similar between groups, with P = 0.8430. Because the underlying measurements were not time-ordered for this calculation, it was not a true lactate clearance rate or longitudinal slope. The results do not justify claiming that DT-NRP cleared lactate faster.
The learning-curve analysis showed a steeper early decline and lower nadir in cannulation time for DT-NRP. Both curves later increased, which the authors suggest could relate to new personnel or more complex cases. These observations support the possibility of efficient adoption among trained teams, but they do not define a validated competency threshold. The service already had three years of NRP experience, and surgeons had experience in rapid recovery procurement plus workshop training and proctoring. Generalizing the learning curve to a new program without that background would be premature.
The most consequential limitation is the absence of organ utilization and recipient outcome data. Procedural efficiency, circuit flow, transfusion exposure, and lactate behavior are useful intermediate measures, but they cannot establish transplant benefit or comparative safety on their own. The sample was also too small to adequately separate intra-abdominal cases with and without thoracic recovery. Nonrandomized selection, donor differences, and team logistics could explain part of the observed advantages. Although the discussion uses the term noninferior, this observational analysis should not be presented as a formal noninferiority trial.
For perfusion professionals, the study supports considering descending thoracic access as an additional A-NRP option within an experienced multidisciplinary program. It offers a coherent technical rationale and encouraging procedural observations, while leaving the central outcome question unanswered. Future multicenter comparisons should account for donor characteristics, concurrent thoracic procurement, blood diversion, and perfusion duration, and should include organ use and recipient outcomes. Until then, the strongest conclusion is that DT-NRP was feasible and associated with favorable operational measures in this service, rather than proven superior for transplantation.
Keywords: Abdominal Normothermic Regional Perfusion, Descending Thoracic Cannulation, Intra-Abdominal Cannulation, Donation After Circulatory Death, Organ Procurement, Venous Drainage, Blood Transfusion, Lactate, Perfusion, Organ Transplantation.
Source: Boyne G, Walker OC, Du J, et al. Transplantation Direct. 2026;12:e2006. Read the original open-access study.
Original educational summary of a study published under CC BY 4.0. Cover artwork is an AI-generated conceptual illustration, not a procedural diagram.
