Fig. 2.

Top: ΔTHb (solid lines) and ΔHbO₂ (dashed lines) averaged over all subjects for control (black) and POTS (gray) groups during the modified Oxford maneuver. Results are shown for illustrative purposes; statistical comparisons are shown in Table 1. NIRS, near-infrared spectroscopy. Middle: corresponding changes in arterial inflow (ΔQ_a; solid lines) and venous outflow (ΔQ_v; dashed lines) for both control (black) and POTS (gray) groups during the modified Oxford maneuver. Bottom: averaged ΔCBFv during the modified Oxford maneuver for control (black) and POTS (gray) groups. The first arrow indicates the administration of SNP, and the second arrow indicates the administration of PE.