Pneumothorax

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108 Pneumothorax

Instruction

Examine this patient’s chest.

Salient features

History

• Sudden onset or rapidly progessive dyspnoea

• Ipsilateral acute pleuritic pain: either sharp or a steady ache

• A small pneumothorax may be asymptomatic

• Obtain history of:

• recent pleural aspiration or insertion of subclavian line (J R Soc Med 1997;90:319–21)
• recent surgeries in head and neck
• abdominal procedures using bowel or peritoneal distension.

• History of asthma, COPD, acute respiratory distress syndrome, pneumonia, trauma to chest

• History of Marfan syndrome

• History of HIV

• History of positive pressure ventilation.

Examination

• Decreased movement of the affected side

• Increased percussion, note:

• trachea may be central (small pneumothorax) or deviated to the affected side (underlying collapse of lung) or the opposite side (large pneumothorax)
• increased vocal resonance with diminished breath sounds.

Proceed as follows:

• Look for clues regarding aetiology:

• Pleural aspiration site
• Infraclavicular region for a bruise of the central line
• Comment if the patient is thin or has marfanoid features
• Inhaler or peak flow meter by the bedside (asthma, COPD).

• Tell the examiner that you would suspect tension pneumothorax when there is tachycardia (>135 beats/min), hypotension and pulsus paradoxus.

Diagnosis

This patient has diminished breath sounds and hyper-resonant note on R/L side of the chest (lesion) caused by pneumothorax secondary to Marfan syndrome (aetiology), and is not breathless at rest (functional status).

Questions

What do you understand by the term pneumothorax?

Air in the pleural cavity.

How would you investigate this patient?

• Chest radiography, both inspiratory and expiratory phases. In critically ill patients, pneumothorax is suspected when:

• the costophrenic angle extends more inferiorly than usual because of air: the ‘deep sulcus sign’ (Fig. 108.1; Radiology 1980;136:25–7)
• the liver appears more radiolucent as a result of air in the cerebellopontine angle, or on the left side, when the air will outline the medial aspect of the hemidiaphragm under the heart.

• Blood gases if the patient is breathless: hypoxaemia depending on the shunting, whereas hypercapnia does not develop.

image

Fig. 108.1 Deep sulcus sign of pneumothorax. (A) On posteroanterior chest radiograph, the costophrenic angle is normally acute (arrow). In a supine patient, a pneumothorax will often be anterior, medial, and basilar. (B) On supine film, the dark area along the right cardiac border and lung base appeared larger (small arrows), and the costophrenic angle much deeper and more acute than normal (large arrow). (C) Tension pneumothorax, with an extremely deep costophrenic angle (large black arrow), an almost completely collapsed right lung (small white arrows) and shift of the mediastinum to the left.

(With permission from Mettler 2004.)

Advanced-level questions

How would you grade the degree of collapse?

British Thoracic Society of grading:

• Small: where there is a small rim of air around the lung

• Moderate: when the lung is collapsed towards the heart border

• Complete: airless lung, separate from the diaphragm (aspiration is necessary)

• Tension: any pneumothorax with cardiorespiratory distress (rare and requires immediate drainage).

How do you estimate the size of the pneumothorax?

The classic chest radiographic appearance is that of a thin, visceral pleural line lying parallel to the chest wall, separated by a radiolucent band devoid of lung markings. The average width of this band can be used to estimate the size of the pneumothorax with a fair degree of accuracy. However, it is usually clinically more convenient to characterize the pneumothorax as small, moderate, large or complete. The estimated size of the pneumothorax and the patient’s clinical status can be useful in guiding management decisions.

How would you manage this patient?

• Small pneumothoraces (<20% in size) spontaneously resolve within weeks.

• Larger ones (irrespective of size) with normal lungs are managed by simple aspiration rather than an intercostal tube as the initial drainage procedure. Aspiration is less painful than intercostal drainage, leads to a shorter admission and reduces the need for pleurectomy, and has no increase in recurrence rate at 1 year.

• When there is rapid re-expansion following simple aspiration, an intercostal tube with underwater seal drainage is used. The tube should be left in for at least 24 h. When the lung re-expands, clamp the tube for 24 h. If repeat radiography shows that the lung remains expanded, the tube can be removed. If not, suction should be applied to the tube. If it fails to resolve within 1 week, surgical pleurodesis should be considered. Video-assisted thoracoscopic surgery with several chest ports allows clear visualization of the pleural cavity for resection of bullae and pleurodesis.

What are the causes of pneumothorax?

• Spontanenous (usually in thin males)

• Trauma

• Bronchial asthma

• COPD: emphysematous bulla (JAMA 1975;234:389–93)

• Carcinoma of the lung

• Cystic fibrosis

• TB (the original descriptions of pneumothorax is commonly associated with TB, JAMA 1931;96:653–7)

• Mechanical ventilation

• Marfan syndrome, Ehlers–Danlos syndrome

• Catamenial pneumothorax: pneumothorax that occurs in association with menstruation.

How would you do a pleurodesis?

By injecting talc into the pleural cavity via the intercostal tube.

In which patients would you avoid doing a pleurodesis?

In patients with underlying cystic fibrosis. These patients may require lung transplantation in the future and pleurodesis may make this procedure technically not feasible.

When would you suspect a tension pneumothorax?

Tension pneumothorax should be suspected in the presence of any of the following:

• Severe progressive dyspnoea

• Severe tachycardia

• Hypotension

• Marked mediastinal shift.

When should open thoracotomy be considered?

It should be considered if there is one of the following present:

• A third episode of spontanenous pneumothorax

• Any occurrence of bilateral pneumothorax

• Failure of the lung to expand after tube thoracostomy for the first episode.

What do you know about Birt–Hogg–Dubé syndrome?

Birt–Hogg–Dubé syndrome is an autosomal dominant condition that includes skin fibrofolliculomas, pulmonary cysts, spontaneous pneumothorax and renal cancer. The condition is a result of germline mutations in the gene FLCN, which encodes folliculin; the function of this protein is largely unknown, although FLCN has been linked to the mTOR pathway. The availability of DNA-based diagnosis has allowed insight into the great variation in expression of FLCN, both within and between families.

Further reading

Sahn SA, Heffner J. Spontaneous pneumothorax. N Engl J Med. 2000;342:868-874. review

OK Williamson (1866–1941), an English physician, described the Williamson sign: BP in the leg is lower than that in the upper limb on the affected side in pneumothorax.

The use of simple aspiration to manage pneumothorax was first reported by OG Raja in 1981 when he was a medical registrar (Br J Dis Chest 1981;75:207–8).

In 1995, a surgeon on a flight from Hong Kong undertook a life-saving, emergency operation on a woman with a spontaneous pneumothorax. The hero, Angus Wallace, was described by emeritus professor of surgery Miles Irving as ‘a typical professor of surgery: ebullient, extrovert, and confident. It was a brilliant piece of improvisation’ (Lancet, 2009;374:1055–6).

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