PDA is the second most common congenital heart disease and the second most prevalent congenital heart malformation. In preterm infants, the prevalence of PDA is high. 45% of preterm infants weighing less than 1750 g have PDA. More than 70% of PDA can be cured by conservative medical medications, but surgical procedures are often required for those PDA that are more gross and severely affect cardiopulmonary function. Premature infants have many characteristics of PDA surgical anesthesia compared with children of other ages due to their incomplete development of various organs, and there are few reports in this area in China. The experience of bedside surgery for PDA in preterm infants in our NICU for more than 1 year is summarized as follows. Clinical materials and methods 1. Clinical materials From October 2009 to May 2011, among 35 children with PDA who had failed conservative medical treatment, there were 22 males and 13 females with gestational age ranging from 27 weeks to 34 weeks and birth weight ranging from 0.72 to 2.25 kg (mean weight 1.48 kg). Among them, there were 17 cases of low birth weight, 15 cases of very low birth weight, and 3 cases of ultra-low birth weight. 33 of the 35 children failed to be treated with ibuprofen for PDA, and 2 cases were treated directly with surgery without ibuprofen because of severe bleeding tendency. Of the 35 children, 29 (83%) had neonatal pneumonia, 26 (74%) had neonatal respiratory distress syndrome, 26 (74%) had neonatal anemia, 18 (51%) had hypoproteinemia, 16 (46%) had severe electrolyte disturbances, 11 (31%) had pulmonary hemorrhage, 8 (23%) had intracranial hemorrhage, 6 (17%) had cardiac insufficiency and 4 (17%) had necrotizing Small bowel colitis was observed in 4 cases (11%). Among the 35 cases, 32 cases were treated with ventilator-assisted respiratory therapy before surgery, and the longest duration of preoperative ventilator therapy was 29 days, among which 5 cases were treated with emergency surgery due to sudden deterioration of preoperative condition. (1) Preoperative diagnosis After admission, all 35 children were given bedside echocardiogram to clarify the diagnosis of PDA. 33 of them were treated conservatively with internal medicine (ibuprofen) for 1~2 courses, and then the echocardiogram was repeated to clarify that the arterial duct was still not closed and the cardiopulmonary function was obviously impaired, so they could not be disconnected from the ventilator or oxygen and were referred to surgery. In the remaining two cases, because of the contraindication of preoperative drug (ibuprofen) treatment, no drug treatment was given, and surgery was performed directly. (2) Surgical anesthesia method All children were operated in the million-class NICU laminar flow monitoring ward. Preoperative preparation: (1) control infection with antimicrobial agents; (2) control pulmonary hemorrhage and intracranial hemorrhage with drugs such as Vk1 for three days before surgery; (3) continuous mechanical ventilation and preparation of two venous accesses before surgery, and continuous monitoring of blood pressure by arterial puncture, usually the posterior tibial artery, dorsalis pedis artery or femoral artery; (4) transfer the child to a constant temperature radiation table before surgery, set the temperature at 32-34 degrees Celsius, and continuously monitor ECG, invasive arterial pressure and oxygen ④Preoperatively, the child is placed on a constant temperature radiation table, set at 32-34 degrees Celsius, and the ECG is monitored continuously. Anesthesia: ①Intravenous anesthesia was used, including midazolam 0.1 mg/kg, fentanyl 5-20 μg/kg, and vecuronium 0.1-0.2 mg/kg; ②Intraoperative systolic blood pressure was maintained at >40 mmHg, and if blood pressure was low, dopamine was pumped up to 20 μg/kg/min; ③Intraoperative transcutaneous oxygen saturation was maintained at >85%, and if saturation is lower than this value during the surgical operation, it is necessary to suspend the operation, hand-controlled breathing, and pure oxygen ventilation to fully inflate the left lung and continue the operation after the blood oxygen saturation improves. Surgical approach: After general anesthesia, the child is placed in the right lateral position, and the incision is made at the 4th intercostal space on the posterior side of the left chest. The left lung was retracted to expose the descending aorta, and the posterior mediastinal pleura on the surface of the descending aorta was incised longitudinally with an electric knife along its long axis, near the spinal side, with the upper end reaching the beginning of the left subclavian artery and the lower end exceeding the arterial catheter by about 1 cm. The descending aortic end of the arterial catheter was fully freed, and one end of the 10-gauge wire was drawn from the upper window of the catheter inward to outward around the back of the descending aorta with right-angle forceps, and then this end was returned from the lower window of the catheter around the back of the descending aorta to complete the loop of the catheter. Methods of closing the arterial catheter: double 10-gauge ligation of the arterial catheter; single 10-gauge ligation of the arterial catheter + titanium clamp clamping; simple titanium clamp clamping of the arterial catheter. Ligation and/or clamping followed by exploration of the catheter area for disappearance of tremor. No closure of the posterior mediastinal pleura. The chest was closed after placement of a drainage tube in the mid-axillary line at the 7th intercostal space, and the patient was returned to the constant warmth box for monitored treatment after surgery. There were no intraoperative deaths, no intraoperative hemorrhage, and the mean arterial pressure increased to different degrees in all 35 children after PDA ligation, with a maximum increase of 30 mm Hg and a minimum increase of 6 mm Hg (mean 13.2 mm Hg). The pulse pressure decreased and the children were ventilated with ventilator-assisted ventilation after surgery for a minimum of 3 days and a maximum of 2 weeks (mean 1 week). Thirty-three of the children recovered well after surgery and were discharged, while two children died due to multifunctional organ failure after surgery. Discussion The arterial duct is a normal channel between the descending aorta and the pulmonary artery during fetal life. In normal newborns, 10-15 hours after birth, the lumen disappears functionally due to contraction of the muscular layer of the ductal wall of the arterial duct, reaching functional closure, and within 3 months the wall progressively closes to anatomical closure. If the closure mechanism is abnormal causing delayed closure of the duct, the ductus arteriosus is not closed. Echocardiography allows a definitive diagnosis. Preterm infants often have persistent open ductus arteriosus because of immature postnatal oxygen-induced ductus arteriosus contraction mechanisms and increased sensitivity of the ductus arteriosus in response to vasoactive substances. According to statistics, there is 1 case of PDA per 2500-5000 live births. The incidence of PDA is significantly higher in preterm infants, and can be as high as 80% in those weighing less than 1000 grams. In 1939, Gross et al. successfully ligated the arterial catheter for the first time, which was a milestone in the surgical treatment of PDA, and PDA became the first precocious disease that could be cured by surgical means. In 1967, Porstman successfully used the cardiac catheter to pass through the artery to fill the unclosed artery with polyethylene sponge plugs. In 1967, Porstman successfully used a polyethylene sponge plug to plug the unclosed artery through the artery, pioneering interventional therapy and enriching the treatment of PDA. Interventional therapy is simple and safe, without the risks associated with open-heart surgery, and patients recover quickly, gradually replacing open-heart surgery. Heymann et al. first reported pharmacological treatment of patent ductus arteriosus. The main drugs include anti-inflammatory pain and ibuprofen (inhibitors of prostaglandins), which promote ductal closure by inhibiting the synthesis of prostaglandins. Compared to anti-inflammatory pain, ibuprofen has the same efficacy and fewer side effects. Ibuprofen is the drug of choice for the treatment of PDA in preterm infants. PDA in preterm infants is usually treated conservatively with medications that can result in a significant reduction in the rate of surgery for PDA with significant hemodynamic significance. Surgery is the mainstay of treatment for those preterm infants who are medically ineffective and who remain ventilator dependent despite appropriate anti-heart failure therapy. In our group, 33 of the 35 children had been treated with ibuprofen for 1 to 2 courses, but the arterial catheter still could not be closed, and the children were still dependent on ventilators or could not be weaned from oxygen. After the surgery, cardiopulmonary function improved significantly. Gradually, he was taken off the ventilator and oxygen and resumed normal growth. The operation took about 30 minutes, with no more than 5 ml of bleeding, minimal trauma, and no incisional infection. We believe that timely surgery is a wise choice for preterm infants with preterm ductus arteriosus who have failed to respond to medications. In the early stage, because of insufficient awareness and poor timing of surgery, 2 children were operated only after the combination of multiple organ failure, especially massive pulmonary hemorrhage, and although the arterial catheter was successfully ligated, it still failed to save the children’s lives. From our experience, a PDA with a diameter of more than half of the diameter of the aortic root has a significant impact on the cardiopulmonary function of the child. Premature infants have incomplete development of various organs and poor adaptability to the external environment. The transfer process from the pediatric ward to the operating room often requires ventilators, warming boxes and many monitoring devices, which require coordination and cooperation of multiple parties and many personnel, and these difficulties make cardiac surgery for preterm infants impossible in many units. The NICU in our unit is a million-class laminar flow ward with complete ventilators and monitoring equipment, and has the necessary aseptic, anesthesia and monitoring conditions to complete the surgery, creating extremely favorable conditions for the success of the surgery. For premature babies, we have also made corresponding improvements in the anesthesia and surgery process. The anesthesiologist closely monitors the child’s heart rate and blood pressure during surgery, especially the transcutaneous oxygen saturation, the latter of which can be used as a sensitive indicator for monitoring cardiopulmonary function during surgery. In children or adults, prolonged compression of the left lung during surgery does not significantly affect cardiopulmonary function, whereas slightly prolonged compression of the left lung in preterm infants often leads to a decrease in oxygen saturation, which in turn affects myocardial contraction and endangers the child’s life. During surgery, if the oxygen saturation drops to 85%, we suspend the operation and wait for the anesthesiologist to fully expand the lung tissue and restore the oxygen saturation to normal before restarting the operation. The arterial ducts of premature infants are so thin that the slightest inadvertence may lead to rupture and life-threatening injury. During surgery, we use the descending aortic end of the catheter to fully free the catheter and pass the silk twice behind the descending aorta to achieve the purpose of looping the catheter, avoiding direct freeing of the catheter, which is easy to operate and greatly reduces surgical risk. For the catheter treatment, the initial use of simple wire ligation to close the catheter or simple titanium clamp clamp, a case of laryngeal nerve injury, postoperative analysis of the cause of the accidental injury is mainly due to the simple titanium clamp clamp when the local tissue is not sufficiently free. Now we use first free the arterial catheter, ligate the catheter with a thick wire, do not pull the catheter when ligating to avoid hemorrhage, and then clamp the catheter with a titanium clamp on the descending aorta side of the ligature line, which can reduce the chance of recanalization and reduce the chance of damage to the laryngeal nerve and incomplete clamping of the catheter tissue. Our data show that timely surgery for coarctation of PDA in preterm infants for whom conservative medical treatment is ineffective can often save the child’s life, and the NICU can meet the need for surgery. The combination of filament ligation and titanium clamp clamping results in low surgical risk and high surgical success rate. Bedside PDA surgery is recommended.