Successful stenting for Budd–Chiari syndrome after pediatric liver transplantation: a case series and review of the literature

Hepatic venous outflow obstruction, known as Budd–Chiari syndrome, is a rare but serious complication of orthotopic liver transplantation and may lead to graft loss. Our aim was to describe a single center experience of percutaneous interventional management of hepatic outflow obstruction post liver transplantation in children. Three children with post-transplant hepatic venous outflow obstruction were treated successfully with percutaneous stent placement. This resulted in long-term resolution of symptoms and was superior to balloon angioplasty both in our series and in cases reported in the literature. Stenting may be the treatment of choice for hepatic venous obstruction after pediatric liver transplantation, particularly if there is a recurrence of stenosis after balloon dilatation.     

A novel approach to endovascular treatment of severe hepatic vein stenoses following liver transplant in children

Gibson C, John P, Amaral J. A novel approach to endovascular treatment of severe hepatic vein stenoses following liver transplant in children.
Pediatr Transplantation 2012. © 2012 John Wiley & Sons A/S. Abstract: Hepatic vein stenoses are a rare but serious complication of liver transplants in children. Restoration of flow by radiological methods often provides a viable treatment option. This technique relies on the interventional radiologist’s ability to advance a guide wire across the obstruction, thus allowing for balloon dilatation and other necessary interventions. Failure to cross the stenosis reduces graft survival and increases patient morbidity. We report two cases with tight hepatic vein stenosis where the guide wire could not be advanced in a conventional approach across the upper end of the stenosis. Utilizing prominent intrahepatic collateral vessels, the stenoses were able to be crossed, facilitating successful PTA with good clinical outcome.     

Management of end-stage central venous access in children referred for possible small bowel transplantation

The 3-year survival after small bowel transplantation (SBTx) has improved to between 73% and 88%. Impaired venous access for parenteral nutrition can be an indication for SBTx in children with chronic intestinal failure. AIM: To report our experience in management of children with extreme end-stage venous access. SUBJECTS: The study consisted of 6 children (all boys), median age of assessment 27 months (range, 13-52 months), diagnosed with total intestinal aganglionosis (1), protracted diarrhea (1), and short bowel syndrome (4), of which gastroschisis (2) and malrotation with midgut volvulus (2) were the causes. All had a documented history of more than 10 central venous catheter insertions previously. All had venograms, and 1 child additionally had a magnetic resonance angiogram to evaluate venous access. Five of 6 presented with thrombosis of the superior vena cava (SVC) and/or inferior vena cava. METHODS: Venous access was reestablished as follows: transhepatic venous catheters (5), direct intra-atrial catheter via midline sternotomy (4), azygous venous catheters (2), dilatation of left subclavian vein after passage of a guide wire and then placing a catheter to reach the right atrium (1), radiological recanalization of the SVC and placement of a central venous catheter in situ (1), and direct puncture of SVC stump(1). Complications included serous pleural effusion after direct intra-atrial line insertion, which resolved after chest drain insertion (1), displacement of transhepatic catheter needing repositioning (2), and SVC stent narrowing requiring repeated balloon dilatation. OUTCOME: Four children with permanent intestinal failure on assessment were offered SBTx, 3 of which were transplanted and were established on full enteral nutrition; the family of 1 child declined the procedure. In the remaining 2 children in whom bowel adaptation was still a possibility, attempts were made to provide adequate central venous access as feeds and drug manipulations were undertaken. One of them received liver and SBTx nearly 3 years after presenting with end-stage central venous access, because attempts to achieve independence from parenteral nutrition had failed. The other child died immediately after a transhepatic venous catheter placement, possibly from a nutritional depletion syndrome as no physical cause of death was found. Direct intra-atrial catheters in transplanted children proved to be adequate for the management of uncomplicated transplantation, although the usual infusion protocol had to be modified considerably, and the lack of access would have been critical if massive blood transfusion had been required during the transplant procedure. CONCLUSION: It was possible to reestablish central venous access in all cases. However, this was time consuming and difficult to assemble a skilled team consisting of one of more: surgeon, cardiologist, interventional radiologist, and transplant anesthetist. Small bowel transplantation is easier and safer with adequate central venous access, and we advocate liaison with an SBTx center at an early stage.     

Hepatic venous reconstruction in pediatric living-related donor liver transplantation--experience of a single center

In pediatric patients submitted to living related liver transplantation, hepatic venous reconstruction is critical because of the diameter of the hepatic veins and the potential risk of twisting of the graft over the line of the anastomosis. The aim of the present study is to present our experience in hepatic venous reconstruction performed in pediatric living related donor liver transplantation. Fifty-four consecutive transplants were performed and two methods were utilized for the reconstruction of the hepatic vein: direct anastomosis of the orifice of the donor left or left and middle hepatic veins and the common orifice of the recipient left and middle hepatic veins (group 1-26 cases), and wide triangular anastomosis after creating a wide triangular orifice in the recipient inferior vena cava at the confluence of all the hepatic veins with an additional longitudinal incision in the inferior angle of the orifice (group 2-28 cases). In group 1, eight patients were excluded because of graft problems in the early postoperative period and five among the remaining 18 patients (27.7%) presented stricture at the site of the hepatic vein anastomosis. All these patients had to be submitted to two or three sessions of balloon dilatations of the anastomoses and in four of them a metal stent had to be placed. The liver histopathological changes were completely reversed by the placement of the stent. Among the 28 patients of the group 2, none of them presented hepatic vein stenosis (p = 0.01). The results of the present series lead to the conclusion that hepatic venous reconstruction in pediatric living donor liver transplantation must be preferentially performed by using a wide triangulation on the recipient inferior vena cava, including the orifices of the three hepatic veins. In cases of stenosis, the endovascular dilatation is the treatment of choice followed by stent placement in cases of recurrence.     

Incidence,impact, and treatment of portal and hepatic venous complications following pediatric liver transplantation: A single‐center 12 year experience

Heffron TG, Pillen T, Smallwood G, Henry S, Sekar S, Casper K, Solis D, Tang W, Fasola C, Romero R. Incidence, impact, and treatment of portal and hepatic venous complications following pediatric liver transplantation: A single‐center 12 year experience.
Pediatr Transplantation 2010: 14:722–729. © 2010 John Wiley & Sons A/S. Abstract: PVT or PVS and HVOO are known causes of graft and patient loss after pediatric liver transplantation. Increased incidences of these complications have been reported in partial livers including DDSLT or LDLT. From 1997 to 2008, 241 consecutive pediatric patients received 271 hepatic grafts at a single center. Median follow‐up is 1856 days. Surgical technique, demographics, lab values, and radiologic imaging procedures were obtained utilizing OTTR^® to evaluate the relationship of portal and hepatic complications with risk factors, patient and graft survival. Grafts were composed of 115/271 (42.4%) partial livers of which 90 (33.2%) were DDSLT and 25 (9.2%) LDLT. Of 271 patients, 156 (57.6%) received whole‐sized grafts. There were six PVC in five patients with one patient requiring retransplantation (0.34%) and no patient deaths. Utilizing all three hepatic vein orifices on the recipient hepatic vena cava and the donor hepatic vein cut short enables a wide hepatic outflow tract unlikely to twist. None of the 241 patients developed early or late complications of the hepatic vein. None of the last 128 consecutive patients who received 144 grafts over seven and a half yr have developed either early or late complications of the hepatic or portal vein. Partial‐graft actuarial survival was similar to whole‐graft survival (87.2% vs. 85.3% at one yr; 76.6% vs. 80.2 at three yr; p = 0.488). Likewise, patient survival was similar between partial grafts and whole grafts (93.8% vs. 93.1% at one yr; 89.8% vs. 87.2% at three yr; p = 0.688) with median follow‐up of 1822 (±1334) days. Patients receiving partial livers were significantly younger and smaller than patients receiving whole livers (p < 0.001). Portal and hepatic venous complications may have negative effects on patient or graft survival after pediatric liver transplantation. In our series, there was one graft and no patient loss related to portal or hepatic venous complications after pediatric liver transplantation over 12 yr.     

Management of late‐onset portal vein complications in pediatric living‐donor liver transplantation

The purpose of this study was to evaluate retrospectively the results of PTA for late‐onset PV complications after pediatric LDLT and to assess whether a meso‐Rex shunt is a viable option for treating restenosis of the PV after PTA in selected cases. Seventy‐five children who underwent adult‐to‐child LDLT were included in this study, and there were six late‐onset PV complications (8.0%). The initial therapeutic approach was PTA, with or without stent: PTA with balloon dilation for three children, PTA with stent placement for one child, and failure to cannulate the occluded PV for two children. A meso‐Rex shunt was performed in the two children after failed PTA: One suffered complete obstruction of the main PV, and the other, restenosis with total thrombosis after PTA with stent. The PTA was a technical and clinical success in four with PV stenosis of the six patients (66.7%), and successful application of a meso‐Rex shunt in the other two children resulted in restoration of PV flow. In conclusion, PTA is a safe and effective procedure for treating late‐onset PV stenosis after pediatric LDLT. However, in growing pediatric recipients with restenosis of the PV after PTA or chronic PV thrombosis, a meso‐Rex shunt may be a better choice for late‐onset PV complications.     

Waiting list mortality for pediatric deceased donor liver transplantation in a Japanese living‐donor–dominant program

Living donor liver transplantation (LDLT) has become a major life‐saving procedure for children with end‐stage liver disease in Japan, whereas deceased donor liver transplantation (DDLT) has achieved only limited success. The annual number of pediatric liver transplantations is approximately 100‐120, with a patient 20‐year survival rate of 81.0%. In 2005, the liver transplantation program at the National Center for Child Health and Development in Tokyo, Japan, was initiated, with an overall number of 560 pediatric patients with end‐stage liver disease to date. In July 2010, our center was qualified as a pediatric DDLT center; a total of 132 patients were listed for DDLT up until February 2019. The indications for DDLT included acute liver failure (n = 46, 34.8%), metabolic liver disease (n = 26, 19.7%), graft failure after LDLT (n = 17, 12.9%), biliary atresia (n = 16, 12.1%), and primary sclerosing cholangitis (n = 10, 7.6%). Overall, 25.8% of the patients on the waiting list received a DDLT and 52.3% were transplanted from a living donor. The 5‐year patient and graft survivals were 90.5% and 88.8%, respectively, with an overall waiting list mortality of 3.0%. LDLT provides a better survival compared with DDLT among the recipients on the DDLT waiting list. LDLT is nevertheless of great importance in Japan; however, it cannot save all pediatric recipients. As the mortality of children on the waiting list has not yet been reduced to zero, both LDLT and DDLT should be implemented in pediatric liver transplantation programs.     

��ѹ�������������ƶ�ͯ ֧������խ5���ٴ�����

目的探讨高压球囊扩张术在儿童支气管狭窄临床应用中的疗效及安全性。方法对天津市儿童医院2010年6-12月住院的5例支气管狭窄患儿(包括先天性狭窄1例),经支气管镜进行高压球囊扩张术,每次球囊扩张1～3min,对比术前及末次球囊扩张术后胸片的改变,并定期随访1～6个月。对其临床资料进行回顾分析。结果 5例患儿经高压球囊扩张2～4次,狭窄段支气管管腔明显增宽,临床症状及体征明显改善,复查胸片肺实变及肺不张均有不同程度好转,肺气肿明显减轻。随访1～6个月,4例肺炎肺不张患儿复查胸片基本正常,1例先天性狭窄患儿未再出现高调金属样咳嗽,胸片示肺气肿消失。结论经支气管镜高压球囊扩张术治疗儿童支气管狭窄是一种安全、有效、简便的方法。     

Interventional treatment of lumen-reconstruction-related complications after pediatric living-donor liver transplantation

Background

Interventional radiology has recently been reported as an effective means of treating complications after liver transplantation. In children, however, the number of such reports is relatively small. In addition, there is ongoing discussion regarding the best interventional devices and methods for specific complications.

Objective

The aim of this study was to determine the value of interventional treatment for vessel and bile duct complications after pediatric living-donor liver transplantation.

Materials and methods

Six cases with lumen-reconstruction-related complications after liver transplantation received intervention. Three cases had hepatic artery thrombosis, one had portal vein stenosis, and two had bilioenteric anastomotic stenosis. Catheter-directed thrombolysis was used to treat cases with hepatic artery thrombosis; balloon dilation and stent placement were used for portal vein stenosis; balloon dilation and drainage were used for bilioenteric anastomotic stenosis.

Results

All interventions were performed successfully, and treatment efficacy was 100 %. Except for one death from multiple organ failure, all other cases survived through follow-up, which lasted up to 18 months. No case had intervention-related complication.

Conclusion

Interventional treatment is safe and effective, and can be the first choice for the treatment of complications associated with pediatric living-donor liver transplantation.     

Post-operative abdominal CT scanning in extrahepatic biliary atresia

A retrospective review of the abdominal CT scans of 26 children with extrahepatic biliary atresia was performed, and the results were correlated with available surgical and pathologic data. Associated congenital anomalies or acquired abnormalities were identified in these patients. Congenital anomalies included polysplenia, venous anomalies and bowel stenosis. Acquired abnormalities developed secondary to cirrhosis, portal hypertension, intrahepatic biliary duct dilatation, and hepatic ischemia. Despite frequent episodes of ascending cholangitis in these children, no hepatic abscesses were identified by CT or by pathologic examination. In conclusion, abdominal CT scanning of children with extrahepatic biliary atresia can define congenital and acquired abnormalities and provide important anatomic data for the surgeons before liver transplantation.     

Sonographic diagnosis of portal venous gas in two pediatric liver transplant patients with benign pneumatosis intestinalis

Penumatosis Intestinalis (gas in the bowell wall) is uncommon in children and is associated with a number of clinical conditions [1] most notably necrotizing enterocolitits in sick neonates. We observed portal venous gas on sonography and benign pneumatosis intestinalis on abdominal raiiography in two children who had recently undergone liver transplantation. Asymptomatic portal venous gas and pneumatosis intestinalis has not been described previously in pediatric liver transplant patients. It is important to recognize the sonorgaphic appearance of portal venous gas since sonography is the imaging modality most frequently utilized for monitoring the allograft post liver transplantation.     

Portal vein obstruction after liver transplantation in children treated by simultaneous minilaparotomy and transhepatic approaches: initial experience

Portal vein thrombosis is a complication that occurs anytime after liver transplantation and can compromise the patient and graft survival. We describe a combined technique for PV recanalization in cases of PV obstruction after liver transplantation. Four children (1%), of 367 subjected to liver transplantation from June 1991 to December 2008, underwent PV recanalization through a combined approach (transhepatic and minilaparotomy). All children received left lateral hepatic segments, developed Portal vein thrombosis (n=3) and stenosis (n=1), and presented with symptoms of portal hypertension after transplantation. PV recanalization was tried by transhepatic retrograde access, and a minilaparotomy was performed when percutaneous recanalization was unsuccessful. Three patients underwent a successful portal recanalization and stent placement with the combined technique. In one patient, the recanalization was unsuccessful because of an extensive portomesenteric thrombosis. The other three children had the portal flow reestablished and followed with Doppler US studies. They received oral anticoagulation for three consecutive months after the procedure and the clinical symptoms subsided. In case of PV obstruction, the combined approach is technically feasible with good clinical and hemodynamic results. It' is a minimally invasive procedure and can be tried to avoid or delay surgical treatment or retransplantation.     

Cerebral venous thrombosis after embolization of pediatric AVM with jugular bulb stenosis or occlusion: Management and prevention

PurposeThrombosis of cerebral arteriovenous malformation after embolization is rare, but can involve the normal venous network with extensive venous thrombosis. We report angioarchitecture findings, our management and prevention strategy for this complication in pediatric AVMs.MethodsIn this 5.5-year retrospective series, we reviewed records of 13 patients under 15 years who were anticoagulated after embolization. In our initial experience 4 children who didn't receive any prophylactic anticoagulation presented with extensive venous thrombosis after embolization (group 1). Following this, nine children with similar angioarchitecture and embolization modalities were treated with prophylactic anticoagulation immediately after embolization (group 2). We analyzed the type of AVM, angioarchitecture, dose of prophylactic anticoagulant, efficacy/complications of treatment and late outcome.ResultsAll patients in group 1 had severe jugular bulb stenosis/occlusion associated with cerebral venous dilatation. In group 2 with similar angioarchitecture, only three patients (33%) developed extensive thrombosis. In both groups, thrombosis occurred within two days of treatment in six children and two weeks in one child. The diagnosis was suspected on intracranial hypertension in five patients and occulomotor disorder in one. One was asymptomatic. All children were treated with therapeutic doses of LMWH (anti-Xa: 0.5–1). No hemorrhagic complications occurred. Good venous remodeling was observed in all but one patient.ConclusionAnticoagulation in extensive venous thrombosis after AVM embolization in children appears to be safe and effective. In cases with angioarchitectural features of dilatation of the cerebral venous network and occlusion/severe stenosis of the jugular bulbs, full dose anticoagulation may be required to prevent thrombosis.     

Hepatic venous reconstruction using the superficial femoral vein in a right‐lobe living donor liver transplant patient with interrupted inferior vena cava

Anatomical abnormalities in patients with BA often include polysplenia, preduodenal portal vein, interrupted retrohepatic IVC, cardiac abnormalities, and situs inversus. In LDLT patients who had congenital vascular anomalies, additional surgical modifications for the reconstruction of hepatic venous branches are sometimes necessary to prevent venous parenchymal congestion. We report a 12‐yr‐old female with post‐Kasai BA with interrupted retrohepatic IVC who underwent right‐lobe LDLT because the left liver graft volume was insufficient. The donor right liver graft had three major hepatic branches, including the RHV, IRHV, and MHV tributary (V8). We performed hepatic venous reconstruction by creating a large, wide triple orifice consisting of the RHV and two SFVs, which were anastomosed to the V8 and IRHV using the donor's SFV as an interposition graft. In conclusion, the reconstruction of venous orifices for right‐lobe LDLT patients with the absent retrohepatic IVC is can be carried out using an SFV graft derived from the living donor or the recipient.     

Outcome after pediatric liver transplantation impact of living donor transplantation on cost

OBJECTIVE: To compare the direct health care cost of living donor liver transplantation (LDLT) with that of cadaver donor liver transplantation (CDLT) in children and identify predictors of cost. STUDY DESIGN: All 16 children who underwent LDLT from January 1997 through January 2002 at Cincinnati Children's Hospital Medical Center comprised the study population. They were matched for age, diagnosis, and nutritional status with 31 children who received CDLT during the same era. A historic cohort analysis was performed. RESULTS: There was no difference in the 1-year mortality rates between both groups. Costs associated with graft retrieval contributed 15.3% and 31% of the initial transplant cost for LDLT and CDLT, respectively. Mean cost of care in the first year was 60.3% higher for LDLT than CDLT (P=.01). Multivariate analysis identified biliary complications and insurance status as predictors of cost for initial transplantation (R(2)=0.57), whereas biliary complications and pediatric end stage liver disease scores were identified as predictors of cost of care in the first year after transplantation (R(2)=0.77). CONCLUSIONS: The comprehensive cost of LDLT in the first year after transplantation is higher than cadaveric transplantation. This must be balanced against the time spent and care needs of patients on the waiting list.     

Status of the venous part of the portal system in infectious-toxic shock in infants with acute pneumonia

As many as 38 children aged 2 to 12 months suffering from acute pneumonia complicated by infectious-toxic shock manifested dilatation of the veins of portal circulation and deposition of a considerable blood volume, which was revealed by ultrasonic examination. The hemodynamic disorders were shown to play the leading part in the genesis of hepatomegaly, followed by hypoxic derangement of the hepatocyte. In infants, who are in a state of infectious-toxic shock, vascular decompensation of the liver is more pronounced and sets in earlier than parenchymatous. Administration of troxevasin (30 mg/kg a day) to the sick children promotes a more rapid elimination of venous dilatation in the system of portal circulation.     

Cardiac achalasia in children. Dilatation or surgery?

Surgical treatment of cardiac achalasia in children is still the main line of treatment with a success rate of 70-80%. Balloon dilatation is less widely used due to inappropriate size of balloons. The authors report on their experience in 11 children with cardiac achalasia over the last 7 years using balloon dilatation as the treatment of choice, 8 boys and 3 girls with ages ranging from 1.5-14 years (average 7.5 years) were investigated. One family (brother and sister) presented with no glucocorticoid deficiency or other anomalies, one patient had mental retardation, the rest had no associated anomalies. All patients presented with vomiting, 7 with dysphagia, 6 with loss of weight, 5 with recurrent chest infection and 2 with retrosternal pain. Radiological diagnosis was accurate in all patients, endoscopy with biopsy were done to confirm diagnosis and exclude other pathology, manometry yielded positive results in 4 patients. Dilatation was done under general anesthesia with fluoroscopic control, balloons were used over a guide wire (balloon sizes were 18-35 mm). Seven patients had 2 sessions and 4 had 3 sessions with radiological follow-up after the second dilatation. Follow-up ranged from 2-7 years: excellent results were achieved in 8 patients (72.7%) with disappearance of symptoms and marked radiologic improvement, 2 still have mild symptoms with overall success (90.9%), one had mild gastroesophageal reflux, controlled medically, and one had mild dysphagia but his status was improved compared to that before dilatation. One patient had recurrent dysphagia necessitating cardiomyotomy (9.1%). Results were not related to age or sex. The authors recommend balloon dilatation in children with cardiac achalasia as the treatment of choice or even as the only feasible treatment.     

֧���ܾ����������ų��������� ��ͯ����������խ�ٴ��о�

??Abstract: Objective To assess the efficiency and safety of the flexible bronchoscopic balloon dilatation tracheoplasty in children?? and discuss the optimal indication and combined therapy of central airway stenosis in children. Methods From July 2009 to April 2012?? 34 cases were diagnosed as central airway stenosis by chest CT scan and bronchoscpy in Shanghai Children's Medical Center??and received the treatment of the flexible bronchoscopic balloon dilatation tracheoplasty. The data about the efficiency?? complication and prognosis of the treatment were collected. Results In the 34 cases?? 16 cases were improved after the treatment and the overall response rate was 47.1%. According to the pathology of the stenosis?? these cases were divided into three types: 9 cases were membranous stenosis?? 5 cases were muscular stenosis and 20 cases were osseous stenosis. The response rate was 47.1%?? 100%?? and 20% respectively. According to the anatomy morphology of the stenosis?? 20 cases were short distance stenosis and the response rate was 75%?? 12 cases were long distance stenosis and the response rate was 8.3%?? 2 cases were funnel stenosis and the response rate was 0. Among these cases?? 3 cases accepted the operation of pulmonary artery sling and tracheal sliding angioplasty?? the total response rate being raised to 55.9%. The most common complication in the flexible bronchoscopic balloon dilatation tracheoplasty was transient oxygen desaturation. Conclusion The severity?? length?? pathology?? indication and time of the treatment should be considered completely before the flexible bronchoscopic balloon dilatation tracheoplasty. The balloon dilatation therapy is suitable for membranous with short distance stenosis. The combined interventional treatment is good for muscular stenosis??and the surgery and palliative treatment is an option for osseous with long distance stenosis.     

Management of hepatic venous obstruction after split-liver transplantation

Stenosis of the hepatic vein anastomosis is an unusual but critical complication after liver transplantation. In pediatric liver transplantation, the scarcity of size-matched donors has required the use of segmental liver allografts, either as reduced-size or split-liver grafts. This report illustrates the primary use of a hepatic vein stent to manage hepatic venous outflow obstruction in a pediatric split-liver recipient, and reviews experience in the management of hepatic venous outflow obstruction after liver transplant using stent methods.     

应用球囊扩张气道成形术治疗儿童支原体肺炎肺不张的探讨

目的 对支气管镜介导下球囊扩张气道成形术治疗支原体肺炎肺不张患儿4～5级气道炎性狭窄的疗效和安全性进行评价.方法 对30例支原体肺炎所致的气道炎性狭窄并肺不张患儿,实施支气管镜介导下球囊扩张气道成形术.分别于术前和最后一次球囊扩张术后胸部CT检查,对肺不张的情况进行评价.所有患儿均接受了1～6个月的随访.结果(1)30例气道狭窄的患儿分别接受球囊扩张1～3次.经过球囊扩张气道成形术后,25例患儿狭窄段管径增大,球囊扩张部位远端肺组织复张;5例狭窄段扩开不明显,其中3例病变部位有肉芽组织形成,经球囊联合冷冻治疗后,球囊扩张部位远端肺组织复张;另2例患儿病程超过3个月,扩张治疗无效.(2)经1～6个月随访,肺复张的28例患儿胸部CT显示扩张治疗部位影像正常,2例扩张治疗无效的患儿胸部CT显示的肺不张范围较前无变化.(3)30例接受此方法 治疗的患儿,20例扩张时出现扩张部位的支气管黏膜轻微出血,5例术后轻微胸痛,没有其他严重并发症发生.结论支气管镜介导下的球囊扩张气道成形术治疗儿童肺部感染后气道狭窄有效、安全.