It is difficult to estimate the ischemic consequences when using partial resuscitative endovascular balloon occlusion of the aorta (REBOA). The aim was to investigate if end-tidal carbon dioxide (ETCO 2 ) is correlated to degree of aortic occlusion, measured as distal aortic blood flow, and distal organ metabolism, estimated as systemic oxygen consumption (VO 2 ), in a porcine model of normovolemia and hemorrhagic shock. Materials and methods: Nine anesthetized pigs (25-32 kg) were subjected to incremental steps of zone 1 aortic occlusion (reducing distal aortic blood flow by 33%, 66%, and 100%) during normovolemia and hemorrhagic grade IV shock. Hemodynamic and respiratory variables, and blood samples, were measured. Systemic VO 2 was correlated to ETCO 2 and measures of partial occlusion previously described. Results: Aortic occlusion gradually lowered distal blood flow and pressure, whereas ETCO 2 , VO 2 and carbon dioxide production decreased at 66% and 100% aortic occlusion. Aortic blood flow correlated significantly to ETCO 2 during both normovolemia and hemorrhage (R ¼ 0.84 and 0.83, respectively) and to femoral mean pressure (R ¼ 0.92 and 0.83, respectively). Systemic VO 2 correlated strongly to ETCO 2 during both normovolemia and hemorrhage (R ¼ 0.91 and 0.79, respectively), blood flow of the superior mesenteric artery (R ¼ 0.77 and 0.85, respectively) and abdominal aorta (R ¼ 0.78 and 0.78, respectively), but less to femoral blood pressure (R ¼ 0.71 and 0.54, respectively). Conclusion: ETCO 2 was correlated to distal aortic blood flow and VO 2 during incremental degrees of aortic occlusion thereby potentially reflecting the degree of aortic occlusion and the ischemic consequences of partial REBOA. Further studies of ETCO 2 , and potential confounders, in partial REBOA are needed before clinical use.