Patent ductus arteriosus flow patterns in the treatment of congenital diaphragmatic hernia

Background: Congenital diaphragmatic hernia (CDH) mortality still remains high, due to lung hypoplasia and persistent pulmonary hypertension of the neonate (PPHN). Effective management of PPHN and time of operation are quite important to the improvement of CDH treatment. In order to determine the optimal time for operation, we monitored PPHN with cardiac ultrasound. Methods: PPHN was assessed with three parameters: patent ductus arteriosus flow patterns (PDAFP), %left ventricular diameter at diastole, and left ventricular fraction of shortening (LVFS). Four patients with an antenatal diagnosis were treated under this protocol. Diaphragm repair was performed when PDAFP became left to right shunt dominant and the pre- and postoperative course was analyzed with regular chart reviews. Results: The alveolar-arterial oxygen difference levels of four patients were 590, 335, 613 and 530 mmHg, and operations were carried out when the patients were 2, 2, 3 and 2 days old, respectively. In three of the four patients (all except case 3) the PDAFP changed from right to left shunt dominant or bidirectional (BD), to left to right shunt dominant within 48 h. The %left ventricular diameter at diastole was relatively stable around the time of operation. The LVFS of all patients decreased after the operation. Only the LVFS of case 3 decreased temporarily to less than 30% (which indicates poor left ventricular function) but recovered. No patients needed extracorporeal membrane oxygenation support. All patients survived the procedure and were extubated. Case 3, who took 10 days to become left to right shunt dominant after the operation, needed home oxygenation therapy for 10 months. Conclusions: PDAFP was a reliable marker of PPHN on a high-frequency oscillatory ventilator to determine the optimal time for the operation for CDH. The optimal time for operation is supposed to be the time when PDAFP become left to right shunt dominant.