**5.1 Conservative management**

Clinically stable patients with small pneumothoraces can be treated with conservative management, and they should stay in the emergency room with a control chest radiograph to perceive the resolution of pneumothorax. Conservative management consists of observing the patient, oxygen therapy, and analgesia [39]. In the case of symptomatic and/or large pneumothoraces, it is indicated to remove the air from the pleural space by simple aspiration or chest tube drainage [40]. Patients with a first episode of primary spontaneous pneumothorax that are hemodynamically stable, with few or no symptoms, and have a small pneumothorax (<2–3 centimeters between the lung and the chest wall or <15% of hemithorax) can be

treated by supplemental oxygen, which accelerates the process of reabsorption of air by the pleura. The observation period should be at least 6 hours; after this time, the patient can be discharged if three conditions are met: absence of progression of the pneumothorax confirmed by a control chest radiograph, compliance of the outpatient treatment plans, and ease of access to emergency medical services. In these cases, the follow-up after discharge should be from 2 to 4 weeks [41].
