ABSTRACT
BACKGROUND: The effects of head-down position on dynamic hemodynamic variables remain without full understanding. We evaluated the effects of steep head-down position on the pulse pressure variation (PPV). METHODS: Forty patients were positioned at 30degrees head-down position after anesthesia induction. We measured the heart rate (HR), arterial blood pressure (BP) and PPV before and 2 minutes after the position change. RESULTS: PPV and HR decreased (9.3 +/- 3.2% to 4.6 +/- 1.8%, 67.2 +/- 11.4 to 62.4 +/- 7.8, respectively) after steep head-down position, whereas the BP increased. Baseline PPV was related with decreases of PPV (r2 = -0.83, P < 0.0001). An 8% PPV threshold discriminated the patients with more than 5% decreases of absolute PPV value. The area under the receiver operating characteristic curve was 0.98 (95% CI = 0.88 to 1.00, P < 0001). CONCLUSIONS: Steep head-down position caused decreases in PPV. Higher PPV at the supine position decreased more after the position change. Further investigations are required to assess the significance, the duration and the relationship with fluid responsiveness of this change.