Objective To evaluate the predictive value of ultrasonography of the respiratory variability index of inferior vena cava internal diameter (IVC-RVI) in preoperative fluid responsiveness evaluation of hip fracture in geriatric patients.Methods A retrospective case-control study was used to analyze 39 cases of elderly hip fractures admitted to the Daping Hospital of Army Medical Center from August 2017 to February 2018,including 15 males and 24 females,aged 65-92 years [(80.9 ±7.9)years].The heart rate (HR),mean arterial pressure(MAP),cardiac output (CO),and cardiac stoke volume (SV)were recorded five minutes after the patient entered the operating room and within 5 minures after capacity load test.The inferior vena cave during expiration (IVCe) and inferior vena cave during inspiration (IVCi) were measured by ultrasound before and after volume load test and the difference in IVC-RVI was calculated.Volumetric positive group were the cases of SV change (△SV) ≥15％ (positive group,n =21),and volume negative group were the cases of △SV ＜15％ (negative group,n=18).The correlations between various ultrasonic parameters and SV were analyzed by comparing HR,MAP,CO,SV,SV,IVCe,IVCi and IVC-RVI before and after the capacity load test.The predictive value of IVC-RVI for preoperative volumetric reactivity in elderly patients with hip fractures was evaluated by using the receiver operative characteristic (ROC) curve and Pearson correlation analysis.Results Prior to the volumetric load test,no significant difference was observed between the two groups concerning HR,MAP,CO,SV,and IVCe (P ＞0.05),IVCi in the positive group was significantly smaller than that in the negative group (P ＜0.05),and IVC-RVI in the positive group was significantly larger than that in the negative group (P ＜0.05).After the volumetric load test,there was no statistically significant difference between the two groups in CO,IVCe,IVCi,and IVC-RVI (P ＞0.05),HR in the positive group was smaller than that in the negative group (P ＜ 0.05),and MAP and SV in the positive group were significantly larger than that in the negative group (P ＜ 0.05).Compared with that before capacity load test,MAP,CO,and SV in the positive group increased after the capacity load test (P ＜0.05),while the HR difference was not statistically significant (P ＞ 0.05).HR,MAP,CO,and SV showed no significant difference in the negative group before and after capacity test (P ＞ 0.05).IVC-RVI assessed the area under the curve (AUC) was 0.80 ± 0.08 for preoperative volumetric responsiveness in elderly hip fractures (P ＜ 0.05),with a critical point of 20.69％,sensitivity of 77.78％,and specificity of 76.19％.After Pearson correlation analysis,IVC-RVI was positively related to △SV (OR =0.367,P ＜0.05).Conclusion Ultrasonography of the respiratory variability of IVC can predict the preoperative fluid responsiveness of hip fracture in geriatric patients and guide for clinical rehydration.