Brachiocephalic vein distensibility during passive leg raising in healthy adults

Abstract Passive leg raising (PLR) is a validated test of fluid responsiveness, but the value of brachiocephalic vein (BCV) distensibility as an ultrasound marker remains uncertain. In this prospective study, 129 volunteers were assessed for eligibility and 122 were analyzed (45 nonfasting controls, 77 fasting). Cardiac output (CO) was measured before and after PLR by echocardiography, and BCV distensibility was calculated from respiratory diameter variation. PLR increased CO in both groups ( P < 0.001). Median ΔCO was lower in fasting participants than in controls (21.05 [12.93–37.32] vs. 29.88 [22.13–39.86], P = 0.038), with lower responder rates at ΔCO ≥ 10% (79.2% vs. 95.6%, P = 0.016) and ΔCO ≥ 15% (74.0% vs. 91.1%, P = 0.032). ΔBCV distensibility did not differ between groups and was not associated with ΔCO overall (Spearman r = 0.148, P = 0.105). ROC analysis showed poor discrimination (AUC 0.38 overall, 0.51 in controls, 0.31 in fasting participants for ΔCO ≥ 15%), and exploratory adjusted analyses did not support an independent association between fasting status and responder status. BCV distensibility showed limited value and poor discriminatory performance as a marker of PLR-induced cardiac output change in spontaneously breathing healthy adults.