Passive leg raising for predicting fluid responsiveness: importance of the postural change.

OBJECTIVE: For predicting fluid responsiveness by passive leg raising (PLR), the lower limbs can be elevated at 45 degrees either from the 45 degrees semi-recumbent position (PLR(SEMIREC)) or from the supine position (PLR(SUPINE)). PLR(SUPINE) could have a lower hemodynamic impact than PLR(SEMIREC) since it should not recruit the splanchnic venous reservoir.

DESIGN: Prospective study

SETTING: A 24-bed medical intensive care unit.

PATIENTS AND PARTICIPANTS: A total of 35 patients with circulatory failure who responded to an initial PLR(SEMIREC) by an increase in cardiac index >/= 10%.

INTERVENTIONS: PLR(SEMIREC), a transfer from the semi-recumbent to the supine position and PLR(SUPINE) were performed in all patients in a random order before fluid expansion (500 mL saline).

MEASUREMENTS AND RESULTS: PLR(SEMIREC), supine transfer and PLR(SUPINE) significantly increased the pulse-contour derived cardiac index (PiCCOplus) by 22 (17-28)%, 9 (5-15)% and 10 (7-14)% (P < 0.05 vs. PLR(SEMIREC) for the latter two), respectively. These maneuvers significantly increased the right ventricular end-diastolic area (echocardiography) by 20 (14-29)%, 9 (5-16)% and 10 (5-16)% (P < 0.05 vs. PLR(SEMIREC) for the latter two) and the central venous pressure by 33 (22-50)%, 15 (10-20)% and 20 (15-29)% (P < 0.05 vs. PLR(SEMIREC) for the latter two), respectively. Volume expansion significantly increased cardiac index by 27 (21-38)% and all patients were responders to volume expansion. If an increase in cardiac index >/= 10% is considered as a positive response to PLR(SUPINE), 15 (43%) patients would have been unduly predicted as non-responders to fluid administration by PLR(SUPINE).

CONCLUSIONS: PLR(SEMIREC) induces larger increase in cardiac preload than PLR(SUPINE) and may be preferred for predicting fluid responsiveness.