ObjectiveTo evaluate the predictive value of mini-fluid challenge for volume responsiveness in patients under shock.MethodsSixty patients diagnosed as shock were included in the study. A 50 mL infusion of physiological saline over 10 seconds and a further 450 mL over 15 minutes were conducted through the central venous catheter. Cardiac output (CO), global end-diastolic volume index (GEDVI), central venous pressure (CVP) and extravascular pulmonary water index (EVLWI) were monitored by the pulse indicator continuous cardiac output monitoring. If the increase of CO after 500 mL volume expansion (ΔCO500) ≥10%, the patient was considered to be with volume responsiveness. The relevance between ΔCO50 and ΔCO500 was analyzed, and the sensitivity and specificity of the ΔCO50 were analyzed by receiver operating characteristic (ROC) curve.ResultsAfter 50 mL volume injection, the heart rate and systolic blood pressure of the two groups did not change obviously. The CVP of non-responders changed slightly higher than that of responders, but neither of them had obviously difference (P>0.05). The CO of responders had increased significantly (P<0.05) which was in accord with that after a further 450 mL volume injection. GEDVI and EVLWI did not change significantly (P>0.05). ΔCO50 and ΔCO500 were strongly correlated (r=0.706, 95%CI 0.677 - 0.891, P>0.05). The area under ROC curve for ΔCO50 was 0.814 (95%CI 0.707 - 0.922).ConclusionThe volume responsiveness of patients under shock can be predicted by mini-fluid challenge study which is related to normal volume expansion and it does not increase the risk of pulmonary edema.