Systematic Review of Plasma/packed Red Blood Cell Ratio on Survival in Ruptured Abdominal Aortic Aneurysms

Background: The ideal perioperative fluid resuscitation for patients with ruptured abdominal aortic aneurysms (rAAAs) is unknown. It has been shown in trauma studies that a higher ratio of plasma and platelets to packed red blood cells confers a mortality benefit. Controversy remains whether this is true also in the rAAA population. The objective of the present study was to investigate the benefit of a greater ratio of plasma/packed red blood cells in patients with rAAAs.

Methods: A health sciences librarian searched four electronic databases, including PubMed, Embase, Cochrane, and ClinicalTrials.gov, using concepts for the terms "fluid resuscitation," "survival," and "ruptured abdominal aortic aneurysm." Two reviewers independently screened the studies that were identified through the search strategy and read in full any study that was potentially relevant. Studies were included if they had compared the mortality of patients with rAAAs who had received a greater ratio of plasma to other component therapy with that of patients who had received a lower ratio. The risk of bias was assessed using the ROBINS-I (risk of bias in nonrandomized studies of interventions) validated tool, and evidence quality was rated using the GRADE (grades of recommendation assessment, development, and evaluation) profile. No data synthesis or meta-analysis was planned or performed, given the anticipated paucity of research on this topic and the high degree of heterogeneity of available studies.

Results: Our search identified seven observational studies for inclusion in the present review. Of these seven studies, three found an associated decrease in mortality with a greater ratio of plasma to packed red blood cells. The remaining four found no significant differences. The overall risk of bias was serious, and the evidence quality was very low.

Conclusions: Overall, the findings from the available studies would suggest that for patients who have undergone open surgery for a rAAA, mortality tends to be decreased when the amount of plasma transfused perioperatively is similar to the amount of packed red blood cells. However, the included studies reported very low-quality evidence based solely on highly heterogeneous observational studies, and further research is warranted.