Mini-fluid challenge test predicts stroke volume and arterial pressure fluid responsiveness during spine surgery in prone position: A STARD-compliant diagnostic accuracy study

The study was designed to verify if mini-fluid challenge test is more reliable than dynamic fluid variables in predicting stroke volume (SV) and arterial pressure fluid responsiveness during spine surgery in prone position with low-tidal-volume ventilation. Fifty patients undergoing spine surgery in prone position were included. Fluid challenge with 500 mL of colloid over 15 minutes was given. Changes in SV and systolic blood pressure (SBP) after initial 100 mL were compared with SV, pulse pressure variation (PPV), SV variation (SVV), plethysmographic variability index (PVI), and dynamic arterial elastance (Ea(dyn)) in predicting SV or arterial pressure fluid responsiveness (15% increase or greater). An increase in SV of 5% or more after 100 mL predicted SV fluid responsiveness with area under the receiver operating curve (AUROC) of 0.90 (95% confidence interval [CI], 0.82 to 0.99), which was significantly higher than that of PPV (0.71 [95% CI, 0.57 to 0.86]; P = .01), and SVV (0.72 [95% CI, 0.57 to 0.87]; P = .03). A more than 4% increase in SBP after 100 mL predicted arterial pressure fluid responsiveness with AUROC of 0.86 (95% CI, 0.71–1.00), which was significantly higher than that of Ea(dyn) (0.52 [95% CI, 0.33 to 0.71]; P = .01). Changes in SV and SBP after 100 mL of colloid predicted SV and arterial pressure fluid responsiveness, respectively, during spine surgery in prone position with low-tidal-volume ventilation.