ILLUSTRATIVE CASE
A 26-year-old man presents to the emergency department complaining of sudden-onset left-side chest pain and mild dyspnea that started while he was playing basketball. He denies any medical problems and takes no medications. He is able to speak in complete sentences as he answers your questions. His O2 saturation is 95% and a chest x-ray reveals a left-side, moderate-to-large pneumothorax.
A primary spontaneous pneumothorax is one that occurs in the absence of underlying clinical lung disease and is not associated with an inciting cause, such as a rib fracture.2 In the United States, the estimated incidence of primary spontaneous pneumothorax is 7.4 cases per 100,000 men and 1.2 cases per 100,000 women.3 The etiology is often unknown, but it is associated with several risk factors, including male sex, smoking, and a tall, thin body habitus.2
The management strategy for stable patients with a primary spontaneous pneumothorax largely depends on pneumothorax size and institutional practice. Multiple methods define pneumothorax size; the US standard cutoff for a small or large pneumothorax is 3 cm, between the pleural line and chest wall at the level of the apex,4 compared with 2 cm in Europe, when evaluating the distance at the hilum in an upright chest radiograph.5 The Collins method uses a formula to calculate the percentage of lung area affected based on 3 distinct measurements on a posterior/anterior upright chest radiograph.6
Management options include observation, supplemental oxygen, simple aspiration, and thoracostomy or chest tube placement. British Thoracic Society guidelines published in 2010 state that only a small pneumothorax can be managed conservatively with observation alone; for a large pneumothorax, the guidelines recommend needle aspiration to achieve lung reinflation, followed by chest tube placement if unsuccessful.5
In practice, management of a large primary spontaneous pneumothorax varies, but the most common treatment is chest tube placement.7 This procedure can be painful and may result in complications such as bleeding, infection, injury to internal structures, or the need for surgical intervention.7 In addition, once a chest tube is placed, hospital admission ensues, lasting an average of 4 days.8 Given these consequences, there is a need for safe and feasible treatment options for a large primary spontaneous pneumothorax.
STUDY SUMMARY
Observational management judged noninferior, with multiple advantages
The Primary Spontaneous Pneumothorax (PSP) trial was a prospective noninferiority trial conducted at 39 hospitals in Australia and New Zealand. This randomized controlled trial compared observational (“watch and wait”) vs interventional (chest tube placement) management of uncomplicated, unilateral, primary spontaneous pneumothorax. Patients ages 14 to 50 years with a moderate-to-large pneumothorax—32% or greater, as defined by the Collins method4—were randomly assigned to a study group to examine the primary outcome of lung reexpansion at 8 weeks.
The intervention included chest tube insertion attached to an underwater seal without suction for 1 hour, followed by an x-ray and clamping for 4 hours if there was no air leak, followed by a repeat chest x-ray. If there was no evidence of radiographic resolution, or if during observation the pneumothorax recurred, the underwater seal was recommenced and the patient was admitted to the hospital, with further intervention at the discretion of the inpatient clinicians. If radiographic improvement was seen, the tube was removed and the patient discharged.
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