Clinical Value Of Gas Partial Pressure Measurement In Diagnosis And Treatment Of Spontaneous Pneumothorax

Objective:To study the predictive value of evaluation in gas partial pressure of pleural cavity and expiration to the closure of visceral pleura in primary spontaneous pneumothroax patients.To study the changes of oxygen partial pressure[p（O₂）]and carbon dioxide partial pressure[p（CO₂）]of the pleural cavity gas of patients with primary spontaneous pneumothorax（PSP）before and after oxygen therapy.Methods:Part 1To collect the expiratory gas by the device which we designed and produced,to collect the gas in the pleural cavity by thoracentesis.To detect the oxygen partial pressure and carbon dioxide partial pressure respectively,and the blood gas analysis of radial artery was done at same time.The data was analyzed and sorted to find the relationship between them.Combine the data with the radiographic information to predict whether the leakage of the visceral pleura is closed.Part 2One hundred and twenty hospitalized PSP patients were divided into two groups:closed pneumothorax group（n=57）and open pneumothorax group（n=51）,according to the[p（O₂）]and[p（CO₂）]of the arterial blood gas,expiratory gas and pleural cavity gas.Twelve patients were excluded.information.To collect the expiratory gas by the device which we designed and produced,to collect the gas in the pleural cavity by thoracentesis after oxygen therapy.To detect the[p（O₂）]and[p（CO₂）]respectively,and the arterial blood gas analysis was done at same time.Results:Part 1Of the 93 patients with spontaneous pneumothorax,49 were classified as closed pneumothorax and 44 as open pneumothorax.By multiple Logistic regression analysis,it was found that[p（O₂）]and[p（CO₂）]had the strongest correlation with the type of spontaneous pneumothorax.According to the ROC curve,the diagnostic accuracy of the ratio of exhaled gas to visceral pleura gas of[p（O₂）]and[p（CO₂）]in spontaneous pneumothorax was higher.The reference value of the ratio of exhaled gas to visceral pleura gas of[p（O₂）]was 1.81,which sensitivity was93.3%,and the specificity was 100%.The reference value of the ratio of exhaled gas to visceral pleura gas of[p（CO₂）]was 0.97,which sensitivity was 78.0%,and the specificity was 85.3%.Part 2There were no significant differences in values of[p（O₂）]and[p（CO₂）]in arterial blood gas between two groups before and after oxygen therapy（P>0.05）.There were no significant differences in values of△[p（O₂）]in arterial blood gas between two groups after oxygen therapy（P>0.05）.There were no significant differences in values of[p（O₂）]and[p（CO₂）]in expiratory gas between two groups before and after oxygen therapy（P>0.05）.There were significant differences in values of[p（O₂）]and[p（CO₂）]in pleurl cavity gas between two groups before and after oxygen therapy（P<0.05）.The level of[p（O₂）]of pleural cavity gas was lower after oxygen therapy than before in patients with closed pneumothorax（P<0.05）.There were no significant differences in values of[p（CO₂）]in pleural cavity gas in patients with closed pneumothorax before and after oxygen therapy（P>0.05）.The level of[p（O₂）]of pleural cavity gas was higher after oxygen therapy than before in patients with open pneumothorax（P<0.05）.There were no significant differences in values of[p（CO₂）]in pleural cavity gas in patients with open pneumothorax before and after oxygen therapy（P>0.05）.Conclusions:The combination of thoracic gas and exhaled gas[p（O₂）]and[p（CO₂）]can predict the closure of visceral pleura in patients with spontaneous pneumothorax.Closed pneumothorax can be judged when the ratio of exhaled gas to visceral pleura gas of[p（O₂）]was more than 1.81 and the ratio of exhaled gas to visceral pleura gas of[p（O₂）]was less than 0.97.This method is simple and effective and suitable for clinical application.High concentration oxygen therapy is beneficial to the absorption of pleural cavity gas and recruitment of lung in patients with close pneumothorax,but it is not the same in patients with open pneumothorax.