Objective:To explore the relationship between hematocrit, early fluid therapy, and clinical outcomes in patients with septic shock, and to provide evidence for fluid resuscitation therapy and prognosis assessment in these patients.Methods:The clinical information of patients with septic shock who were diagnosed and treated in the Emergency Intensive Care Unit (EICU) of the First Affiliated Hospital of Wenzhou Medical University from January 1, 2018 to December 31, 2020 were collected. Taking the survival or death of patients 28 days after admission as the end point of clinical research, the patients were divided into the survival and death groups. After analyzing the basic data of the two groups, the univariate and multivariate COX regression analyses were used to analyze the evaluation value of Δ Hematocrit (HCT) d2-d1 and ΔHCT d3-d1 on the prognosis of patients with septic shock. At the same time, the Kaplan-Meier survival curve was used to analyze the overall survival rate of patients with septic shock, and the smooth curve fitting graph was used to verify its relationship with net fluid intake and death. Results:There were 241 cases in the survival group and 67 cases in the death group. Univariate COX analysis showed statistically significant differences between the survival and death groups in acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) ( P=0.0006), red cell volume distribution width (RDW) ( P=0.0043), age ( P=0.0184), ΔHCT d2-d1 ( P=0.0136), ΔHCT d3-d1 ( P=0.0204), and white blood cell (WBC) ( P=0.0444). Multivariate COX analysis showed that ΔHCT d2-d1 ( P=0.0115) and ΔHCT d3-d1 ( P=0.0029) were independent risk factors for death in EICU patients with septic shock. ΔHCT d2-d1 and ΔHCT d3-d1 were divided into three groups according to the three-digit method. The Kaplan-Meier survival curve showed no significant difference among the three groups in the overall survival rate related to ΔHCT d2-d1 ( P=0.16), but there was a statistically significant difference in the overall survival rate among the three groups related to ΔHCT d3-d1 ( P=0.025). The smooth fitting curve of ΔHCT d3-d1, net fluid intake, and prognosis showed that ΔHCT d3-d1 was negatively correlated with net fluid intake, and the middle ΔHCT d3-d1 group had the best prognosis. Conclusions:The value of ΔHCT d3-d1 is related to the net fluid intake of patients with septic shock. An appropriate decrease in HCT on the third day can improve the prognosis of patients with septic shock. The dynamic changes of hematocrit can provide a certain basis for fluid resuscitation and prognosis evaluation in patients with septic shock.