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Tension pneumothorax is normally associated with trauma,1–3 and ventilated patients.2,4,5 It is a rare diagnosis that should not be missed and may be overlooked in other settings. It may not present with all the “classic” signs leading to a potential delay in treatment.1
While serving on a nuclear submarine a 23 year old sailor presented acutely unwell after exercise. He was an extremely fit sportsman of average height and build who was a smoker with no significant medical history.
He was dyspnoeic, and complaining of sudden left sided pleuritic chest pain. On examination he was sweaty and tachycardic with deteriorating consciousness, becoming rapidly weaker and confused. There was reduced expansion and absent breath sounds on the left side, his trachea was deviated to the right, neck veins were prominent, and apex beat was not palpable. Of note, there was no hyper-resonance on the affected side.
He was placed on high flow oxygen and positioned to maintain his airway. Because of large pectoral muscle mass, attempts at needle thoracocentesis via the second intercostal space proved difficult, and only provided transient benefit. On piercing the parietal pleura with blunt dissection through the fifth intercostal space, there was a reassuring release of air and the patient promptly improved. A 24 French gauge intercostal drain was then inserted.
No imaging facilities are available on board, therefore progress was assessed by clinical examination only. The drain remained in situ with a persistent air leak without re-expansion of the lung until day 4, when the patient coughed violently resulting in re-inflation of his lung. After a further 24 hours with no recurrence, the drain was removed and the patient remained on light duties for the remaining duration of the patrol (four weeks), with an uneventful recovery.
Subsequently the patient was referred for video assisted thorascopic surgery, where no significant pleural or pulmonary defect was found, and he had a pleural abrasion on the affected side. He recovered quickly back to full fitness, and was counselled to give up smoking. He has been passed fit for further service on submarines.
A pneumothorax is the collection of air in the potential space between the parietal and visceral pleura. A tension pneumothorax is the presence of intrapleural air under positive pressure throughout the entire respiratory cycle. Without prompt diagnosis and treatment this condition is usually fatal. Severe cardiorespiratory embarrassment occurs with a prompt fall in Pao2 and decline in stroke volume and cardiac output because of impaired venous return from raised intrathoracic pressure.5 In this case the patient already had a considerable oxygen debt from his vigorous exercise immediately before the event, which no doubt contributed to his rapid compromise.
The incidence of spontaneous tension pneumothorax is rare: a search of Medline shows only five previous case reports,1,2 but between 1% to 3% of unrecognised pneumothoraces may tension without treatment.1,2 Primary pneumothorax describes those with no underlying clinical lung disease and is more common in young men (aged 15–34) and in smokers.2,6,7 Incidence is estimated at 18–28/100 000 per year for men and 1.2–6/100 000 per year for women.8,9 Recurrence rates in the absence of underlying lung disease or further treatment have been estimated at between 19% to 54%10–12 and are increased by continuation of smoking, and height.11,12
A tension pneumothorax is an absolute indication for an intercostal chest drain.3,7 Furthermore, the British Thoracic Society now recommend using a cannula with a minimum of 4.5 cm in length to overcome the problems of pectoral muscle mass.7
In around 80%–90% of cases with primary spontaneous pneumothorax a cause can be found with either computed tomography or thoracoscopy, these are often subclinical blebs, bullae, or cysts.13,14 This submariner had a chest radiograph that was normal three years before this event as part of routine screening for pressurised submarine escape training. Indications for video assisted thorascopic surgery include occupational risk7; during the procedure a patient can undergo resection of pleural blebs and bullae as well as pleurectomy or pleural abrasion.
In this case changes in ambient pressure cannot be implicated as a submarine is at atmospheric pressure (or thereabouts) at all times and no significant rapid changes in pressure were recorded. Neither variations in ambient atmospheric pressure nor exercise are associated with increased incidence of spontaneous pneumothorax.7,9,15
Tension pneumothorax is a clinical diagnosis and this case highlights the absolute importance of rapid recognition and treatment of such a serious condition. Previous case reports have suggested that some clinicians are not aware that tension pneumothorax can occur in the absence of trauma or artificial ventilation.1 In any suspected pneumothorax evidence of mediastinal shift should be carefully looked for using tracheal position and apex beat, although these can be inconsistent findings.1