A pneumothorax is said to be spontaneous if it occurs in the absence of trauma or underlying pathology. For instance an apparently spontaneous pneumothorax in someone with emphysema is to be considered as secondary rather than primary spontaneous for the purpose of this section.
The incidence of admissions for primary spontaneous pneumothorax in the UK has been found to be 16.7 / 100,000 / year in males and 5.8 / 100,000 / year in females. The condition typically occurs in tall thin men between 20 and 30 years of age. Approximately 75% are current smokers.
A pneumothorax present before take-off or occurring during climb may result in a tension pneumothorax owing to the decreasing ambient pressure. This can lead to incapacitation and possibly death. At best, a pneumothorax would be distracting and could induce a degree of hypoxia.
Recurrence is common with 20–60% events at 5 years. Risk factors for recurrences are:
In addition contralateral recurrences occur in 15–30% of cases. Therefore patients who have undergone unilateral surgical intervention remain at increased risk of developing a pneumothorax on the contralateral side for some years. The likelihood of a recurrence decreases exponentially over time. Half the recurrences happen in the first year, a quarter in the second year, one eighth in the third year etc.
Current surgical techniques generally involve Video Assisted Thoracic Surgery (VATS) with apical resection (whether bullae are visible or not) or stapling of bullae, and (but not always done) pleurodesis by abrasion, using a sand paper type of material. This may be augmented by chemical pleurodesis or/and peeling of strips of pleura. The procedure may be unilateral or bilateral. Pleurectomy is now rarely performed as it is mostly unnecessary. It has a significant morbidity. Relapse is possible even after surgery.
It must be understood that different combinations of techniques have different rates of relapse. MEs should therefore not assume that an applicant who underwent surgery is necessarily eligible for a Medical Certificate at a certain point in time.
The following table, compiled by CAA after meta-analysis of some 18 studies, gives an indication of the estimated recurrence rate depending on the procedure(s) performed if any.
| Bilateral VATS + subtotal pleurodesis | Recurrence rate: no data. However it is safe to assume 3% or less |
| Unilateral VATS + subtotal pleurodesis | Recurrence rate ~ 3% Contralateral ~ 5-15% |
| Unilateral VATS, no pleurodesis | Recurrence rate ~ 10-16% Contralateral ~ 5-15% |
| Conservative treatment | Recurrence rate ~ 20-60% Contralateral ~ 5-15% |
Most recurrences following surgery occur in the first 12–18 months post intervention.
It is possible that an applicant who underwent bilateral Pleurectomy, or VATS with pleurodesis, could obtain a Medical Certificate 6 month post-surgery, perhaps restricted to multicrew operations for 6–12 months. In contrast someone who underwent unilateral bullectomy only may have to wait 18 to 24 months, while an applicant treated conservatively may have to wait up to a few years before becoming eligible for a Medical Certificate. An applicant with a history of recurrent spontaneous pneumothorax is unlikely to be issued a certificate unless surgery has been undertaken.
The following information should be provided:
