Correct!
4. A + C
Asymptomatic pneumothoraces do not always need drainage and this depends on the patient's comorbidities (2). A rough rule of thumb is a 10% or larger pneumothorax may need drainage, smaller ones usually do not. Depending on the patient, interventions may be required. For example, a patient with severe pulmonary fibrosis and a 5% pneumothorax may benefit from intervention. However, in this case, the patient was completely asymptomatic and had good home support, transport and monitoring and therefore normally could have been sent home. The reason he was not, is that he lived at a much higher altitude. Based Boyle's law sending him to a higher altitude with a pneumothorax would likely have led to a significant increase in size. Boyle's law states that pressure and volume are inversely related such that P1V1 = P2V2, in a closed system at a constant temperature. While in theory the patient is not a closed system, the law still applies to the pneumothorax which is almost a closed system.
The gold standard for diagnosis of pneumothorax is a thoracic CT (2). Since there was disagreement about interpretation of the chest x-ray, a thoracic CT was performed (Figure 3).
Figure 3. Representative images from thoracic CT scan.
What abnormalities does the thoracic CT scan show?