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

For predicting fluid responsiveness by passive leg raising (PLR), the lower limbs can be elevated at 45° either from the 45° 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.

Prospective study

A 24-bed medical intensive care unit.

A total of 35 patients with circulatory failure who responded to an initial PLR_SEMIREC by an increase in cardiac index ≥ 10%.

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).

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.

PLR_SEMIREC induces larger increase in cardiac preload than PLR_SUPINE and may be preferred for predicting fluid responsiveness.