Abstract: Objective To study the changes of oxygen partial pressure［p(O2)］and carbon dioxide partial pressure
［p(CO2)］of the pleural cavity gas before and after oxygen therapy in patients with primary spontaneous pneumothorax (PSP).
Methods One 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. The two groups were given high concentration oxygen mask for 6 hours, and then the blood gas, expiratory
gas and pleural cavity gas were measured again. The levels of p(O2) and p(CO2) of the arterial blood, expiratory gas and
thoracic oxygen partial pressure before and after oxygen therapy were compared and analyzed. Results There were no
significant differences in values of p(O2) and p(CO2) in arterial blood gas before and after oxygen therapy between the two
groups (P＞0.05). There were no significant differences in values of Δp(O2) in arterial blood gas after oxygen therapy between
the two groups (P＞0.05). There were no significant differences in values of p(O2) and p(CO2) in expiratory gas before and
after oxygen therapy between the two groups (P＞0.05). The level of p(O2) of pleural cavity gas was lower after oxygen therapy
than that before oxygen therapy in patients with closed pneumothorax (P＜0.05). The level of p(O2) of pleural cavity gas was
higher after oxygen therapy than that before oxygen therapy in patients with open pneumothorax (P＜0.05). There were no
significant differences in values of p(CO2) of pleural cavity gas before and after oxygen therapy between the two groups (P＞
0.05). Conclusion The high concentration oxygen therapy is beneficial to the absorption of pleural cavity gas and
recruitment of lung in patients with close pneumothorax, but the effect on open pneumothorax is not obvious.

Key words: pneumothorax, blood gas monitoring, transcutaneous, primary spontaneous pneumothorax, oxygen partial pressure, carbon dioxide partial pressure, closed pneumothorax, open pneumothorax