Effect of Controlled Expiratory Pressures on Cerebrovascular Changes During Valsalva Maneuver

Abstract

This study aimed to investigate the effects of Valsalva maneuver (VM) with the controlled expiratory pressures on vascular stiffness of common carotid artery (CCA) and cerebral hemodynamic changes using diagnostic ultrasonography. Twenty-seven healthy participants (mean and standard deviation of age = 22.78 ± 1.89) performed 30 and 40 mmHg VM. The right CCA stiffness index and pulse wave velocity (PWV) were measured before (PRE) and after (POST) VM. The peak systolic velocity (PSV), resistance index (RI), and heart rate (HR) were measured before (PRE) and after (POST1 and POST2 during the first and the second 15 s, respectively) VM. Near-infrared spectroscopy (NIRS) was utilized to measure regional oxygen saturation (rSO2) and oxyhemoglobin (HbO) on the left and right prefrontal cortex. Stiffness index decreased by 1.76 (p < 0.001) from PRE to POST only after 30 mmHg VM. PWV decreased by 0.69 m/s (p < 0.001, 30 mmHg) and 0.34 m/s (p = 0.022, 40 mmHg) in POST. Conversely, PSV increased by 5.36 cm/s (p = 0.031, 30 mmHg) and 4.77 cm/s (p = 0.04, 40 mmHg) in POST2. Increase in RI (p = 0.017) and decrease in HR (p = 0.003) occurred only after the 40 mmHg VM. Right HbO decreased after 30 mmHg VM (p = 0.023) from PRE to POST1, and right rSO2 increased after 40 mmHg VM (p = 0.036) from VM (during) to POST1. Both 30 and 40 mmHg VM showed a significant improvement in PWV and an increase in PSV. However, at 30 mmHg VM, a significant decrease in HbO was observed after VM owing to increased cerebral oxygen exchange, and at 40 mmHg VM, an rSO2 increase was observed after VM owing to high vascular pressure. Additionally, the increased pressure and rSO2 at 40 mmHg may have been caused by increased RI. The results indicated that the 30 mmHg VM was more effective on CCA stiffness than the 40 mmHg VM.