Objective:To investigate the applied effect of airway lavage of fiberoptic bronchoscope under computed tomography(CT)location combined with ultrasound monitoring diaphragmatic movement in mechanical ventilation of pediatric severe pneumonia.Methods:A total of 70 pediatric patients with severe pneumonia who received mechanical ventilation in The People's Hospital of Liupanshui City and Liupanshui Maternal and Child Health Care Hospital from October 2022 to October 2023 were selected,and they were divided into a control group and an observation group according to the random number table method,with 35 cases in each group.The control group did not undergo CT examination for lung before lavage with bronchoscopy,while the observation group received CT examination before airway lavage.Both two groups simultaneously adopted B ultrasound to monitor diaphragm movement.Heart rate,respiration,oxygen saturation,respiratory mechanics index,pediatric early warning score(PEWS)and modified pneumonia survivor index(mPIRO)score were detected before and after lavage,and the movement and thickness of diaphragm of children were measured by B ultrasound.Results:The heart rate and respiratory frequency of two groups after treatment were significantly lower than those before treatment,and the blood oxygen saturation was significantly higher than that before treatment.The heart rate and respiratory frequency of the observation group were respectively(80.23±10.07)times/min and(18.11±5.03)times/min,which were significantly lower than those of the control group,and the blood oxygen saturation was significantly higher than that of the control group,and the differences were statistical significance(t=3.397,3.939,7.719,P<0.05),respectively.The pulmonary pressure,peak pressure,plateau pressure,average airway pressure,chest pressure and abdominal pressure of two groups after treatment were significantly lower than those before treatment,and the levels of the above indicators in the observation group were significantly lower than those in the control group,with statistical significances(t=12.323,8.141,16.733,12.298,11.375,18.248,P<0.05),respectively.The PEWS scores and total scores of body temperature,pulse,respiration and blood pressure of two groups after treatment were significantly lower than those after treatment,and the above scores in the observation group were significantly lower than those in the control group,with statistical significance(t=67.309,58.148,35.997,30.218,5.271,P<0.05),respectively.The mPRIO scores and total scores of age,test indicators of laboratory,symptom duration,respiratory distress index and treatment plan in two groups after treatment were significantly higher than those before treatment,and the above scores in the observation group were significantly higher than those in the control group,with statistical significances(t=7.432,7.153,7.268,5.088,4.645,4.091,P<0.05),respectively.The diaphragm movement and thickness of two groups after treatment were significantly higher than those before treatment,and the above indicators in the observation group were significantly higher than those in the control group,with statistical significances(t=63.444,6.803,P<0.05),respectively.Conclusion:Compared with conventional airway lavage,the airway lavage of fiberoptic bronchoscope under CT location combined with B ultrasound of monitoring diaphragm has higher accuracy and reliability.