Thermodilution-determined Internal Jugular Venous Flow

Abstract

PURPOSE: Cerebral blood flow (CBF) increases 20% during whole body exercise although a Kety-Schmidt-determined CBF is reported to remain stable; a discrepancy that could reflect evaluation of arterial vs. internal jugular venous (IJV) flow and/or that CBF is influenced by posture. Here we test the hypothesis that IJV flow, as determined by retrograde thermodilution increases during exercise when body position is maintained. METHODS: Introducing retrograde thermodilution, IJV flow was measured in 8 healthy humans at supine and upright rest and during exercise in normoxia and hypoxia with results compared to changes in ultrasound-derived IJV flow and middle cerebral artery mean velocity (MCA Vmean). RESULTS: Thermodilution determined IJV flow was in reasonable agreement with values established in a phantom (R=0.59, p<0.0001) and correlated to the ultrasound-derived IJV flow (n=7; Kendall's tau, 0.28, p= 0.036). When subjects stood up, IJV blood flow decreased by 9±13 (mean±SD)% (219±57 to 191±73 ml·min, p<0.0001) and the influence of body position was maintained during exercise (p<0.0001). Exercise increased both IJV flow and MCA Vmean (p=0.019 and p=0.012, respectively) and the two responses were similar (p=0.50). During hypoxia, however, only MCA Vmean responded with a further increase (p<0.0001). CONCLUSION: As determined by retrograde thermodilution, IJV flow seems little sensitive to hypoxia, but does demonstrate the about 15% reduction in CBF when humans are upright and, provided that body position is maintained, also the increase in CBF during whole body exercise. . . . Published ahead of PrintMedicine & Science in Sports & Exercise ® Published ahead of Print contains articles in unedited manuscript form that have been peer reviewed and accepted for publication. This manuscript will undergo copyediting, page composition, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered that could affect the content. termined by termined retrograde ther retrograde the rate the the about 15% 5% reduct is maintained is maintained, , also the incr also the inc words ds: : cerebral blo cereb Copyright © 2016 American College of Sports Medicine Thermodilution-determined Internal Jugular Venous Flow

Cerebral lactate uptake during exercise is driven by the increased arterial lactate concentration

“…A second catheter was introduced retrograde into the right internal jugular vein using the Seldinger technique and advanced to the bulb of the vein. Proper positioning of the catheter was assumed if the participants reported a mild pain behind the ear during insertion of the guide wire (15) and could hear a rapid saline infusion into the catheter (16). A third catheter was inserted into the median cubital vein and advanced into the right atrium.…”