Differential Cardiac Responses After Passive Leg Raising: A Brief Report

Purpose This study retrospectively examined the hemodynamic effects of passive leg raising (PLR) in mechanically ventilated patients during fluid removal, prior to spontaneous breathing trials. In previous studies, we had noticed varying cardiac responses after PLR completion, particularly in positive tests. Methods Using a bioreactance monitor, we recorded and analyzed hemodynamic parameters, including stroke volume and cardiac index (CI), before and after PLR in post-acute ICU patients. Results We included 27 patients who underwent 60 PLR procedures. In preload-unresponsive patients, no significant CI changes were observed (CIt—6 = 3.5 ± 1.5 vs CIt9 = 2.9 ± 1.2; p =0.361), while in preload-responsive patients, two distinct CI response types to PLR were identified: a transient peak with immediate return to baseline (CIt—6 = 2.7 ± 0.7 vs CIt9 = 3.1 ± 1.1; p = 0.282) and a sustained CI elevation lasting beyond the PLR maneuver (CIt—6 = 2.6 ± 0.7 vs CIt9 = 3.6 ± 0.4; p = 0.002). The latter was particularly noted when ΔCI during PLR exceeded 25%. Conclusion Our findings suggest that in certain preload-responsive patients, PLR can induce a more sustained increase in CI, indicating a possible persistent hemodynamic effect, potentially due to a combination of autotransfusion and sympathetic activation affecting venous return. Further research in larger cohorts and more comprehensive hemodynamic assessments are warranted to validate these observations and to elucidate the possible underlying mechanisms. Bioreactance provides a noninvasive yet effective method for hemodynamic monitoring in the post-resuscitation phase of care.