Pneumothorax is a common complication after EA/TEF repair, the incidence of pneumothorax in this cohort is 45%. Severe pneumothorax can affect the respiratory and circulatory system, even endanger life. The treatment strategies of pneumothorax include conservative observation, thorax puncture, and thoracic drainage, and most patients can often be cured. However, the pathogenesis of pneumothorax after EA/TEF repair has rarely been discussed in previous reports. In this study, we reviewed the clinical data of 188 patients with Gross type C EA/TEF and found that anastomotic leakage and mechanical ventilation were independent risk factors for pneumothorax. However, mechanical ventilator parameters could not be considered to be related to pneumothorax.
Anastomotic leakage, as one of the complications with a high incidence after EA/TEF repair , is closely related to pneumothorax, and our data also supports this view. The clinical manifestations of anastomotic leakage are sometimes similar to pneumothorax, such as dyspnea and decreased blood oxygen, which can be identified by chest radiograph or esophagography. However, the coexistence of these two complications is not conducive to the prognosis of these patients . Therefore, close attention should be paid to whether patients with anastomotic leakage have pneumothorax at the same time; and patients with pneumothorax should also be alert to whether anastomotic leakage has occurred at the same time. Postoperative thoracic drainage has become a routine operation, but some scholars believe that it can’t reduce the incidence of postoperative respiratory complications and mortality , nor can it prevent the occurrence of pneumothorax and pleural effusion , even in 10% of patients had no clinical significance in postoperative indwelling thoracic drainage . In this study, thoracic drainage tubes were routinely placed in all patients after surgery, which we believe that it was beneficial for some patients to observe the characteristics of thoracic drainage fluid. However, the issue of prophylactic thoracic drainage after EA/TEF repair still needs to be explored in prospective studies.
Previous studies have shown that there is a certain relationship between mechanical ventilation and pneumothorax [17, 18], but the causes of pneumothorax have not been analyzed in detail, and the sample size is very small. In this study, the results suggested that mechanical ventilation was one of the possible risk factors for pneumothorax, and we further compared and analyzed the specific parameters of mechanical ventilation, however, the results did not support the correlation between mechanical ventilation parameters and occurrence of pneumothorax. In addition, there was no significant relationship between mechanical ventilation and anastomotic leakage, as shown in Supplementary Table 1. Inconsistencies as to the above results, we consider that it may be associated with the following factors. First of all, the patients of early years (before 2014) didn’t routine receive mechanical ventilation after EA/TEF repair, and only some patients with other complications, respiratory failure, and high anastomosis tension might receive mechanical ventilation. Therefore, the comparison results of these patients may exist bias. In addition, postoperative mechanical ventilation was a continuous treatment process, and the parameters of mechanical ventilation were also constantly adjusted according to the patients’ conditions. In this study, parameters were selected when pneumothorax appeared, but the parameters at other time points might be different between the pneumothorax and the non-pneumothorax groups. Greenough  believed that neonates should be subjected to simultaneous mechanical ventilation at a lower PIP to reduce lung trauma, air leakage, bronchopulmonary dysplasia and other problems. Horn  found that high PEEP would lead to reduced blood perfusion in the diaphragmatic muscle, thus affecting respiration in animal experiments. In summary, the relationship between mechanical ventilation and pneumothorax still needs further studies to explore.
Some scholars  believed that the application of continuous positive airway pressure (CPAP) during the withdrawal period or after the removal of endotracheal intubation might be related to the production of pneumothorax, but only 2 cases were mentioned in their study, and the values of PEEP and FiO2 were not provided. Diez  reported 3 patients with pneumothorax after tracheal intubation and CPAP, and the PEEP values were 5, 6 and 6 cmH2O, respectively. The authors believed that some children needed CPAP for respiratory support after extubation, but the PEEP value should not be too high . High PEEP should be avoided in critically ill patients or when intraoperative anastomosis was obviously difficult. In this cohort, 2 patients developed pneumothorax after tracheal intubation and CPAP, and their PEEP values were 4 and 5 cmH2O, respectively, which were lower than the former report . In addition, Piyush  believed that application of CPAP after extubation after EA/TEF repair might not increase the risk of anastomotic leakage, and our data also supported this view (as shown in Supplementary Table 1). Rational application of CPAP after surgery can help patients to go offline. Therefore, based on the results of this study and previous reports, we still can’t clearly determine the relationship between CPAP and pneumothorax.
However, there are some limitations in this study. Surgical procedures and details, and perioperative management (especially the use of mechanical ventilation) changed over time, and access to surgical details and postoperative complications information was limited. Furthermore, the sample size in a single center and the high proportion of giving up and losing follow-up patients also limited the conclusions in this study. Thus, the relationship between mechanical ventilation and pneumothorax still needs to be further explored in future multi-center studies with large sample size.