The changes in blood flow velocity in the internal jugular vein under conditions of variable intrapulmonic pressure and gravitational effect

Background We explored the dynamics of changes in the blood flow velocity in the internal jugular vein (IJV) under conditions of changing intrapulmonary pressure and gravitational influence in healthy volunteers. Methods Color duplex ultrasonography of the right IJV was performed in 25 healthy volunteers of both genders. The dopplergram of the blood flow spectrum was recorded in the right IJV in the horizontal supine position of the participants, and 3 minutes after the volunteers had attained the new position due to the lifting the bed back section at the 30°. We recorded the maximum (Max) and minimum (Min) linear of blood flow velocity (cm/s). In each position, the measurements were carried out sequentially at positive end-expiratory pressure (PEEP) values of 0, 5, 10 cmH2O after 3 minutes by process of changing the level of PEEP. Quantitative data were presented as arithmetic mean (M), standard deviation (SD) and compared using the Wilcoxon rank-sum test. Results Our data demonstrated that negatively related influence of continuous positive airway pressure on IJV blood flow velocity: Max/Min 57.40±13.10/20.68±7.80 cm/s (PEEP 0 cmH2O), 39.00±18.80/14.63±4.90 (PEEP 5 cmH2O), 30.83±7.30/13.25±2.90 (PEEP 10 cmH2O). The blood flow velocity values are increased after 30° head elevation in PEEP 5 and 10 cmH2O in comparison to 0° values. Conclusions The constant positive airway pressure 5-10 cmH2O in a person in supine position decreasing blood flow velocity in IJV. The 30° head elevation eliminates this effect. ### Competing Interest Statement The authors have declared no competing interest.