Changes in diaphragmatic ultrasonography findings and their association with postoperative complications in children undergoing pulmonary resection

BACKGROUND Few studies have investigated the changes in diaphragmatic function and their association with postoperative pulmonary complications (PPCs) in paediatric patients after lung resection. OBJECTIVE This study aimed to evaluate diaphragmatic function using ultrasound after lung resection and its influence on PCCs in children. DESIGN Prospective observational study. SETTING A tertiary children's hospital. PATIENTS Children aged 6 years or less who were scheduled for video-assisted thoracoscopic lung resection. INTERVENTION Ultrasonographic measurements of diaphragmatic excursion (DE) and thickening fraction (TF) were performed for three epochs: before anaesthesia induction (T0), 1 h postoperatively (T1) and 24 h postoperatively (T2). The thickening fraction is calculated from the thickness of the diaphragm at end expiration and end inspiration at each time point. DE T1 /DE T0 , DE T2 /DE T0 , TF T1 /TF T0 and TF T2 /TF T0 (%) were calculated. The incidence of PCCs was also determined. MAIN OUTCOME MEASURES The primary outcomes were changes in diaphragmatic excursion and thickening fraction over time, from T0 to T2. The secondary outcomes were the association between ultrasound parameters of diaphragm function and the occurrence of early PPCs within 3 days. RESULTS Data from 74 children were analysed. On the operated side, both diaphragmatic excursion and thickening fraction decreased at T1 and recovered slightly at T2, and were significantly lower than the T0 values. Children with PPCs had significantly lower DE T2 /DE T0 and TF T2 /TF T0 scores on the operated side than those without PPCs. According to the receiver operating characteristic analysis, the DE T2 /DE T0 (< 61.1%) on the operated side was associated with PPCs with an area under the curve of 0.764. CONCLUSIONS Peri-operative diaphragmatic function assessed by ultrasonography changed after lung resection in children. The diaphragmatic excursion and thickening fraction decreased postoperatively, and a prolonged decrease in diaphragmatic excursion was associated with pulmonary complications after lung surgery in children. CLINICAL TRIAL REGISTRY ClinicalTrials.gov, NCT04400370