Preliminary Pathogenesis Investigation And Risk Factors For Recurrence After Thoracoscopic Surgery Of Primary Spontaneous Pneumothorax

BACKGROUND AND OBJECTIVES:Primary spontaneous pneumothorax usually attack previously healthy person without underlying diseases. Bullae or subpleural blebs are very common in PSN patients in the surgery or chest CT. About the mechanism of the bullae and subpleural blebs formation,there are several hypotheses, but no hypothesis can fully explain. There are several common characteristics of PSN. PSN is mostly found in the male adolescence with ectomorphic stature, chest flatness is very common. Only bullectomy usually have high recurrence rate, but bullectomy plus pleurodesis will evidently decrease the recurrence rate. Residual apical space is usually found on the chest X-ray after surgery. The objective of this study is to analyze and compare the physical characteristics, like height, body weight and body mass index, especially focusing on the chest physical characteristics, like chest flatness, lung volume, lung average density and intrapleural pressure of PSN patients and healthy controls or other thoracic disease patients, further to preliminarily probe the possible mechanism and pathogenesis. Preventing recurrence is difficult because its pathogenesis and mechanisms are not well known. If risk factors contributing to postoperative recurrence can be identified and improved, then a lower rate of recurrence could be achieved. The aim of this study is to describe the risk factors associated with the ipsilateral recurrence of primary spontaneous pneumothorax after thoracoscopic surgery.METHODS:The data of 652 cases primary spontaneous pneumothorax from from January 2008 to December 2012 were retrospectively reviewed. The physical characteristics were reviewed and compared with healthy controls at the same age. The chest flatness of 99 cases primary spontaneous pneumothorax with chest CT data were measured and compared with 82 cases healthy controls in four CT levels. The lung volume and lung average density of 32 cases primary spontaneous pneumothorax whose chest CT could be used for reconstruction were measured and compared with 10 cases of hyperhidrosis patients. Intrapleural pressure of 43 cases primary spontaneous pneumothorax who accepted chest close drainage after the first attack were measured and compared with 39 cases of mediastinum tumor who accepted thoracoscopic surgery. The records of 248 primary spontaneous pneumothorax patients with a follow-up of more than 2 years after thoracoscopic surgery were reviewed and analyzed retrospectively. Two groups were divided according to recurrence. Univariate and multivariate binary logistic regression analysis were used to find the possible risk factors.RESULTS:The age distribution of primary spontaneous pneumothorax, no matter first attack or recurrence, was like the Gaussian distribution and the summit was 17 to 18. In the comparison of body physique between the primary spontaneous pneumothorax patients from 16 to 18 years old with the normal healthy controls from 16 to 18, the height of primary spontaneous pneumothorax was little higher than the control, but it didn’t reach statistics significance. The body weight of primary spontaneous pneumothorax was little lower than the control, but it didn’t reach statistics significance. The body mass index of primary spontaneous pneumothorax was lower than the control with statistics significance. The chest flatness of the primary spontaneous pneumothorax patients was significant heavier than that of the controls in both left and right side in four different levels. The lung volume of primary spontaneous pneumothorax both in male and female were smaller than that of the controls with statistics difference. The average lung density of primary spontaneous pneumothorax and control had no significant difference. The minimum intrapleural pressure and pressure difference of primary spontaneous pneumothorax were significant different than that of the controls. But the maximum inprapleural pressure of primary spontaneous pneumothorax had no significant difference with that of the controls. Twelve patients experienced primary spontaneous pneumothorax recurrence after thoracoscopic surgery. Patients with primary spontaneous pneumothorax recurrence were younger than patients with no recurrence. The postoperative air leakage time in the recurrence group was longer than in the non-recurrence group. In the recurrence group, more patients did not undergo pleurodesis than in the non-recurrence group. The variables of age, height, weight, body mass index, air leakage time and pleurodesis (with or without), with a P value less than 0.2 in univariate analysis, were enrolled in multivariate analysis. The findings showed that younger age and the absence of pleurodesis were associated with a higher risk of postoperative ipsilateral recurrence of primary spontaneous pneumothorax (P=0.003 and 0.001, respectively).CONCLUSIONS:PSN is more common in ectomorphic male adolescence. The distribution of age onset is Gaussian distribution and the summit of age onset is 17 to 18. The BMI of PSN is significantly lower than the healthy controls of the same age. The chest flatness of PSN in four different dimension are significantly evident than the controls. The lung volume of PSN is significantly lower than the controls; whereas the lung average density has no significant difference. The minimum intrapleural pressure and pressure difference of PSN is significantly different than the controls. these results remind us that the pathogenesis of PSN is related to the imbalance of body vertical development and lung development. The imbalance inflects in the lower lung volume, lower BMI and more evident chest flatness. These imbalances further cause the intrapleural pressure to be more negative, especially in the apical thoracic cavity. The increased intrapleural pressure plays an important role in the formation of bullae, subpleural blebs and apical ELCs. This study revealed that the absence of pleurodesis and younger age are possible risk factors for recurrence of primary spontaneous pneumothorax after thoracoscopic surgery. Therefore, thoracic surgeons should give much more attention to pleurodesis, especially in younger patients.