ObjectiveTo evaluate hepatic venous Doppler parameters under varying inspiratory effort levels in healthy adults using ultrasound, providing a theoretical basis for assessing the impact of inspiratory effort on hepatic venous blood return. MethodsA cross-sectional study was conducted from December 2024 to March 2025, enrolling 61 healthy adults. Inspiratory effort was quantified via portable pulmonary function testing, measuring inspiratory volume (IV) during quiet breathing, moderate inspiratory effort, and maximal inspiratory effort. Hepatic venous Doppler parameters (a-wave, s-wave, d-wave peak velocities) were assessed bedside under these three conditions. Correlation analyses and linear regression models were used to explore relationships between IV and hepatic venous flow parameters. ResultsA total of 61 participants completed screening, with a mean age of 27.03 ± 4.73 years (24 males, 39.0%). Although male participants had advantages in height and weight, no significant differences in inspiratory volume (IV), hepatic venous a-wave, s-wave, d-wave peak velocities, or s/d ratio were observed between men and women across all breathing states (all P>0.05). Significant negative correlations were identified between IV and a-wave (r=?0.68, 95%CI: ?0.75 to ?0.59), s-wave (r=?0.56, 95%CI: ?0.65 to ?0.45), and d-wave (r=?0.33, 95%CI: ?0.46 to ?0.20) velocities. Linear regression equations were established as follows:a-wave (cm/s) = 22.06 - 0.23 × IV (ml/kg ideal body weight); s-wave (cm/s) = 34.96 - 0.26 × IV (ml/kg ideal body weight); d-wave (cm/s) = 25.82 - 0.11 × IV (ml/kg ideal body weight).The s/d ratio decreased significantly with increasing inspiratory effort (1.37 ± 0.38 vs. 1.23 ± 0.24 vs. 1.15 ± 0.22; F=9.91, P<0.001). However, only a weak negative correlation (r=?0.28, P<0.001) was observed between inspiratory effort and s/d ratio. ConclusionInspiratory effort demonstrates a strong negative correlation with hepatic venous blood peak flow velocities in healthy adults. While the s/d ratio shows a downward trend with deeper inspiration, the association is weak.
