OBJECTIVES: The aim of this study is to determine which maneuvers result in greatest cross-sectional area (CSA) of the internal jugular vein (IJV) and reduce collapsibility as measured by ultrasound during simulated venipuncture. METHODS: A total of 52 healthy adult volunteers were prospectively studied in an academic emergency department. Cross-sectional area of the IJV was recorded at baseline, with Valsalva, hepatic pressure, and a combination of hepatic pressure plus Valsalva. Subjects were studied in supine and Trendelenburg. Measurements were repeated using pressure applied to the ultrasound transducer to simulate venipuncture and evaluate degree of IJV collapse. Repeated measures analysis of variance models were used to assess the effects of the maneuvers on the diameter equivalent of the cross-sectional area (CRADE). RESULTS: With simulated venipuncture, both Valsalva and Trendelenburg position were significantly (P < .0001) associated with increased CSA of the IJV. Valsalva in either Trendelenburg or supine position was associated with the largest CRADE (1.20 and 1.13 cm, respectively). Without simulated venipuncture, CSA of the IJV were increased in all settings (P < .0001), but the relative impacts of Valsalva and Trendelenburg position were similar. Hepatic pressure had no impact on CSA of the IJV (P = .94). CONCLUSIONS: All maneuvers with the exception of hepatic pressure led to a statistically significant increase in IJV CSA as compared with baseline with and without simulated venipuncture. Valsalva was the only maneuver, when used alone or in combination, to increase the CSA by greater than 50% and prevent collapse by 50% or more under simulated venipuncture.