Abstract: Objective To investigate the clinical value of bedside ultrasound combined with alveolar-arterial oxygen gradient (PA-aO2) in children with septic shock undergoing fluid resuscitation. 
Methods A total of 38 children with septic shock admitted to the First Department of Intensive Care Medicine, Hebei Children′s Hospital were selected and divided into conventional group (n=19) and experimental group (n=19) by random number table method. After admission, all the children were given comprehensive treatment including initial anti-shock (20 mL/kg sodium acetate ringer′s injection), anti-infecion treatment and respiratory support. The conventional group continued fluid resuscitation after initial fluid resuscitation according to the International Guideline for Management of Sepsis and Septic Shock (6 h target of early target-oriented treatment), and the experimental group was given dynamic evaluation of hemodynamics after initial fluid resuscitation based on bedside ultrasound and PA-aO2 monitoring, to guide subsequent fluid resuscitation. General data, PA-aO2 at 6 h, 24 h and 48 h after fluid resuscitation and heart rate (HR) and mean arterial pressure (MAP) at 6 h after fluid resuscitaion, lactic acid clearance rate at 24 h after fluid resuscitaion,vasoactive drug score at 48 h after fluid resuscitaion, total fluid intake at 48 h after fluid resuscitaion, and the number of patients undergoing blood purification therapy at 48 h after fluid resuscitaion were compared between the two groups. 
Results There was no statistical significance in gender, age, weight, warning score, critical illness score, HR and MAP at admission, blood lactic acid and PA-aO2 in the two groups. The difference of interaction between groups, time points and time points between groups were statistically significant with respect to PA-aO2  at 6 h, 24 h, and 48 h after fluid resuscitation in the two groups (P＜0.05). There was no statistical significance in HR, MAP, lactate clearance at 24 h after fluid resuscitation and vasoactive drug score at 48 h after fluid resuscitation. The total fluid intake at 48 h after fluid resuscitation in experimental group was significantly less than that in conventional group, and the number of patients undergoing blood purification therapy was less than that in conventional group, showing significant differences. 
Conclusion Bedside ultrasound combined with PA-aO2 can accurately guide fluid management in children with septic shock, optimize volume status, reduce fluid intake and the risk of pulmonary edema, avoid invasive treatment of blood purification, relieve pain and benefit children. 

Key words: shock, septic, ultrasonography, alveolar-arterial oxygen gradient