Objective:To investigate the effect of pulmonary ultrasound B-line score on the guidance and prognosis of early fluid resuscitation in patients with severe acute pancreatitis(SAP).Methods:90 patients with SAP were divided into control group(n=45)and observation group(n=45)according to the different ways of fluid management.Both groups received positive fluid therapy guided by the EGDT strategy.The control group used increased lung rales and oxygen desaturation as a sign of reverse fluid resuscitation,while the observation group used lung ultrasound B-line score to guide fluid management.The total liquid balance was compared between the two groups at the initial 6 h,1 d,2 d and 48 h.The tissue perfusion and oxygen metabolism indexes[oxygenation index(PaO2/FiO2),blood lactate and central venous oxygen saturation(ScvO2)]were compared between the two groups at 0,6,12 and 24 h.The levels of B-type natriuretic peptide(BNP)and intra-abdominal pressure(IAP)were compared between the two groups at the time of enroll-ment,24 and 48 h after treatment,and the endpoint events[6 h resuscitation compliance rate,incidence of multiple organ dysfunction syndrome(MODS)and mortality]were compared between the two groups.Results:The total amount of fluid balance in the observation group was less than that in the control group at the initial 6 h,1 d,2 d and the first 48 h(P＜0.05).The PaO2/FiO2 and blood lactate in the two groups decreased with time,and PaO2/FiO2 in the observation group was higher at each time point after resuscitation(P＜0.05),blood lactate was lower(P＜0.05),the ScvO2 of the two groups increased with time,and the observation group was higher at 24 h of resuscitation(P＜0.05).BNP and IAP levels in both groups increased over time,and the observation group was lower at each time point after resuscitation(P＜0.05).The 6-hour resuscitation compliance rate in the observation group was higher than that in the con-trol group,and the incidence of MODS was lower than that in the control group(P＜0.05).There was no statistically significant differ-ence in the 28-day mortality rate between the observation group and the control group(P＞0.05).Conclusion:Pulmonary ultrasound B-line score has high clinical value in guiding early fluid resuscitation in SAP patients.1t is helpful to adjust the amount of fluid resusci-tation in time,effectively improve the levels of PaO2/FiO2 and ScvO2,reduce the level of blood lactate,improve the microcirculation of patients,reduce the risk of fluid overload,and improve the overall prognosis of patients.