Fig. 1.

Absolute values of power spectrum densities (PSDs) for mean arterial pressure (MAP) at 0.05 Hz (A) and 0.10 Hz (D), middle cerebral artery velocity (MCAv) at 0.05 Hz (B) and 0.10 Hz (E), and posterior cerebral artery velocity (PCAv) at 0.05 Hz (C) and 0.10 Hz (F) during squat-stand maneuvers for three interventions. The frequency at which the PSD reached peak amplitude (either 0.05 Hz or 0.10 Hz) was used as a basis for sampling the point estimates for coherence, phase, and gain. At 0.05 Hz, MCAv and PCAv PSD during indomethacin and hypocapnia interventions were reduced compared with the no-intervention condition; at 0.10 Hz, MCAv PSD during indomethacin and hypocapnia interventions and PCAv PSD during the hypocapnia intervention were reduced compared with the no-intervention condition (see Table 1 for details).