Doing No Harm with Primary Spontaneous Pneumothorax

Spontaneous pneumothorax can occur as a primary process in the absence of underlying lung disease or secondarily in the presence of a predisposing lung disorder. Differentiating between the two is critical because patients with lung disease severe enough to cause a pneumothorax are much less likely to tolerate the event. In contrast, primary spontaneous pneumothorax (PSP) characteristically affects men younger than 30 with asthenic body types; a population with a higher capacity for tolerating V/Q mismatch.

Guideline recommendations for management of PSP vary due to limited evidence, but mostly favor intervention in some form if the pneumothorax is significantly sized. To examine this approach, the PSP investigators randomized 316 patients with moderate-to-large PSP to receive immediate intervention with a small-bore chest tube or conservative watchful waiting. The primary endpoint of lung re-expansion within 8 weeks was achieved in 98.5% of patients in the intervention group and 94.4% in the conservative cohort. The difference was within the prespecified noninferiority margin of -9 percentage points (risk difference, −4.1 percentage points; 95% confidence interval, −8.6 to 0.5; P=0.02 for noninferiority).

Iatrogenesis must also be considered when balancing the risks and benefits of a procedure. In this study, 41 patients in the intervention group had an adverse event, versus only 13 in the conservative group (relative risk, 3.32; 95% CI, 1.85 to 5.95). Nineteen patients in the intervention group had an adverse event leading to prolonged hospitalization, life-threatening illness, or intervention to manage these outcomes. Adverse events included hemothorax, infection, and severe chest pain or breathlessness.

These results suggest that minimalism may be favored in the right patient, within the right clinical context, and with the right (or left) pneumothorax.

The following NEJM Journal Watch summary explains the study and results in more detail.

Jason T. McMullan, MD, MS, FAEMS reviewing Brown SGA et al. N Engl J Med 2020 Jan 30 Broaddus VC. N Engl J Med 2020 Jan 30

Dogma, and the American College of Chest Physicians, calls for treating large spontaneous pneumothoraces with tube thoracostomy and subsequent hospitalization, even in young healthy patients without signs of physiologic derangement (NEJM JW Emerg Med May 2001 and Chest 2001; 119:590). British Thoracic Society recommendations allow a trial of needle aspiration prior to tube thoracostomy (Thorax 2010; 65:Suppl 2). Although we know the risks associated with both procedures, the risks of not treating pneumothoraces remain poorly defined.

To better calculate the risk-benefit ratios of various treatment options for spontaneous pneumothorax, researchers randomized 316 patients in 39 Australian and New Zealand hospitals to drainage or observation. Patients in the treatment group had a small-bore chest tube placed; tube removal and discharge were possible if the pneumothorax resolved after 1 hour of water seal and 4 hours of clamping. Patients in the observation group were watched for at least 4 hours and discharged without pneumothorax drainage if no supplemental oxygen was needed, ambulation was comfortable, and repeat chest x-ray was stable.

During an 8-week follow-up interval, 98.5% of the treatment group and 94.4% of the observation group had complete pneumothorax resolution. Only 15% of the observation group ultimately required drainage; observed patients experienced fewer complications and spent less time out of work or admitted to the hospital. Pneumothorax recurrence was higher in the treatment group.

Comment: Less may be more in stable, healthy patients with a primary spontaneous pneumothorax. Most complications were related to treatment and not the underlying pneumothorax. As an editorialist points out, given that chest tube placement is implemented more aggressively in the U.S. than in Australia or New Zealand, implementation of an observation-first strategy in the U.S. may avoid even more harm.

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Ahmad is a 2019-2020 editorial fellow at the New England Journal of Medicine. He is from Toronto, Canada where he is completing his training in pulmonary medicine at the University of Toronto.