Predictability of passive leg raising test on anesthesia-induced hypotension in patients undergoing cardiac surgery

ABSTRACT

BACKGROUND: Hypotension often occurs after induction of general anesthesia. Although preload status has been considered as an important factor for the occurrence of this hypotension, there have been inconsistent results on this topic. The dynamic preload parameters have not been studied as a predictor of hypotension, and therefore we hypothesized that the passive leg raising (PLR) test, a dynamic preload parameter, could predict anesthesia-induced hypotension and conducted a prospective clinical study. METHODS: In 40 patients undergoing elective cardiac surgery, mean arterial pressure (MAP), stroke volume variation, stroke volume (SV) and cardiac index (CI) were measured using arterial line and FloTrac(TM)/Vigileo(TM) system before, during and after PLR test, respectively. Occurrence of anesthesia-induced hypotension was recorded. The ability of PLR test to predict hypotension was evaluated by receiver operating characteristic (ROC) curve analysis. RESULTS: The incidence of hypotension was 90%, which includes 12.5% of refractory hypotension. Changes in MAP and CI induced by PLR test predicted hypotension (area under ROC curves 0.722 and 0.788, respectively). Changes in SV and CI induced by PLR test predicted refractory hypotension (area under ROC curves 0.863 and 0.789, respectively). CONCLUSIONS: Our results suggest that PLR test can predict hypotension and refractory hypotension occurring after induction of anesthesia in patients undergoing cardiac surgery.