Physiological aspects of the determination of comprehensive arterial inflows in the lower abdomen assessed by Doppler ultrasound

The splanchnic circulation has been described as the "blood-giver of circulation" and is believed to play a major role in overall cardiovascular regulation [1]. The splanchnic system receives nearly 30% of the cardiac output through three large arteries: the coeliac and the superior and inferior mesenteric arteries. Hemodynamics in the splanchnic organs are altered under various stressful conditions, such as during physical activity and in the postprandial state [2], due to balancing of tone between sympathetic and vagus activity; consequently, clinical assessment of the splanchnic circulation could potentially provide valuable information regarding hepato-gastrointestinal disease [3-5] and cardiac dysfunction [6].Previous Doppler ultrasound studies that measured splanchnic blood flow in a "single vessel with small size volume", such as the superior mesenteric, coeliac artery, or portal vein, were concerned solely with the target organ in the gastrointestinal area [2,7-9]; therefore, evaluation of alterations in these single arterial blood flows under the various states were sometimes limited to small volumes, even though there was a relatively large change in flow. Evaluation of the comprehensive arterial blood flow in the lower abdomen (BFAb), including the liver, spleen, gastro-intestine, kidney, and pelvic organs as a multiple arterial function, may potentially be a feasible method of determining the distribution of abdominal blood-flow volume or disorder in cases of splanchnic or cardiovascular dysfunction, as well as the distribution following nutritious meal intake or physical exercise [10,11].Our previous studies used ultrasonography to assess whole arterial BFAb hemodynamics: BFAb was obtained by subtracting blood flow in the bilateral proximal femoral arteries [left femoral artery (LFA) and right femoral artery (RFA)] from blood flow in the upper abdominal aorta (Ao) above the coeliac artery bifurcation [10-14].This method of quantitative assessment is a c