A Review of Surgical Management of Congenital Pulmonary Airway Malformations (CPAM): A Decade of Experience

Congenital pulmonary airway malformation (CPAM) (previously named congenital cystic adenomatoid malformation) is a rare abnormality, first described in 1949. CPAM results from adenomatoid proliferation of the terminal bronchioles causing cyst formation, which may impair normal alveolar growth. It occurs more commonly in males and has an estimated incidence of 1:11000 to 1:35000. Most are diagnosed on routine antenatal ultrasonography. Most involve lower lobes, occasionally lesions are bilateral. CPAM lesions are usually managed by surgical removal in childhood due to the risk of serious infection, and potential for malignant change. A recent meta-analysis has favoured surgical management.

Historically, correction of CPAM was by open thoracotomy and surgical resection. This has evolved, however, and since 2008 more than 50 surgical corrections have been carried out thoracoscopically at King's College Hospital. The perioperative anaesthetic management of these children has also evolved, with the increasing use of selective lung ventilation.

The age range at surgery is variable, usually 1 - 14 years, and just over half being asymptomatic. Anaesthetic techniques are variable: for example, the deployment of selective lung ventilation techniques, the choice of anaesthetic agents and the types of invasive monitoring. Surgical duration is typically 3-4 hours. A degree of hypercarbia occurs in most cases during the procedure because of reduced minute ventilation to facilitate surgical access, and the absorption of carbon dioxide insufflated into the pleural space. Around 1/3rd receive blood transfusions. Perioperative complications include: respiratory problems causing hypoxia, requirement for re-intubation, conversion to open thoracotomy, bradycardia, surgical emphysema and sometimes the requirement for prolonged post-operative respiratory support including ventilation, CPAP and chest drain management, bronchopulmonary fistulae, and chylothorax and rarely seizures and cerebral infarction.

In general, post-operative care includes at least 24 hours critical care and another 6-7 days in hospital. The mainstay of early post-operative pain control is either with morphine using a nurse controlled intravenous analgesia system, or with epidural analgesia. These are supplemented with oral analgesic regimens. Children who were preoperatively symptomatic seem more likely to develop perioperative complications.

Objective The purpose of this investigation is to review all children who underwent CPAM surgery over the last 10 years at a single regional centre and carry out a descriptive evaluation of pre-operative factors, anaesthetic and surgical factors, peri- and post-operative morbidity, mortality and subsequent long term outcome.

Methods A retrospective review of all CPAM resections performed since 2008 at a single centre. The data will be retrieved from electronic and paper based medical records, anaesthetics records and operation notes. A prospective analysis of the post-operative course and events will be undertaken. A detailed evaluation of these children in relation to their health, growth and development will be carried out via a structured 20-minute telephone interview with prior consent.

Analysis Outcomes will be compared across preoperatively symptomatic and asymptomatic groups using Mann-Whitney/Wilcoxon test or Student t test for continuous data or the chi square for categorical data. All tests were 2-tailed, and P< 0.05 was considered statistically significant.