Brain tissue pulsation responses to a low-level expiratory resistance manoeuvre: A pilot healthy volunteer study

Pulsatility of the brain has been hypothesised to be linked to intracranial pressure (ICP), although the nature of this relationship remains poorly understood. We used a low-level expiratory resistance manoeuvre to characterise brain tissue pulsation (BTP) responses in a pilot healthy volunteer study. BTPs were measured using a transcranial tissue Doppler ultrasound prototype in 10 healthy volunteers at rest and during the manoeuvre. Measurements of mean arterial pressure (MAP), pulse pressure (PP), and heart rate (HR) were also recorded. One-way repeated-measures ANOVA compared changes between baseline, each phase of the manoeuvre, and recovery. Bulk BTP amplitude increased significantly during the initial phase compared with baseline (P = 0.004). A non-significant decrease was observed as the manoeuvre continued, with values decreasing below baseline during the late phase, followed by an increase above baseline during recovery. HR increased significantly during the late phase (P = 0.015). No significant changes were observed in MAP or PP. Bulk BTP amplitude demonstrated a dynamic response during low-level expiratory resistance, characterised by an initial increase followed by a non-significant decrease over the remainder of the manoeuvre. The physiological mechanisms underlying these observations remain uncertain. Future studies incorporating direct ICP measurements and complementary physiological monitoring are needed to clarify the relationship between BTPs and intracranial dynamics.