CHEST PAIN AND SHORTNESS OF BREATH
A 29-year-old woman complained of a sudden onset of right-sided chest pain with shortness of breath. It woke her from sleep at 3.00 am. The pain was made worse by a deep breath and by coughing. The breathlessness persisted over the 4 h from its onset to her arrival in the emergency department. She has a slight non-productive cough. There is no
relevant previous medical history except asthma controlled on salbutamol and beclometasone. There is no family history of note. She works as a driving instructor and had returned from a 3-week holiday in Australia 3 weeks previously. She had no illnesses while she was away. She has taken an oral contraceptive for the last 4 years.
She has a temperature of 37.4°C, her respiratory rate is 24/min, the jugular venous pressure is raised 3cm, the blood pressure is 110/64mmHg and the pulse rate 128/min. Peak flow rate is 410L/min. In the respiratory system, expansion is reduced because of pain. Percussion and tactile vocal fremitus are normal and equal. A pleural rub can be heard over the right lower zone posteriorly. There are no other added sounds. Otherwise the examination is normal.
• What is the likely diagnosis?
• How can it be confirmed?
This woman has had a sudden onset of pleuritic pain, breathlessness and cough. The physical signs of tachypnoea, tachycardia, raised jugular venous pressure and pleural rub would fit with a diagnosis of a pulmonary embolus. The peak flow of 410 L/min indicates that asthma does not explain her breathlessness.
The differential diagnosis would include pneumonia, pneumothorax and pulmonary embolism. The clinical signs do not suggest pneumothorax or pneumonia. Possible predisposing factors for pulmonary embolism are the history of a long aeroplane journey 3 weeks earlier, oral contraception and her work involving sitting for prolonged periods. Other predisposing factors such as intravenous drug abuse should be considered. The ECG shows a sinus tachycardia. The often-quoted pattern of S-wave in lead I, Q-wave and T inversion in lead III (S1Q3T3) is not common except with massive pulmonary embolus. Other signs such as transient right ventricular hypertrophy features, P pulmonale and T-wave changes may also occur. The chest X-ray is normal, ruling out pneumothorax and lobar pneumonia.
A ventilation–perfusion lung scan could be done looking for a typical mismatch with an area which is ventilated but not perfused. This result would have a high probability for a diagnosis of pulmonary embolism. A pulmonary arteriogram has been the ‘gold standard’ for the diagnosis of embolism but is a more invasive test. In cases with a normal chest
X-ray and no history of chronic lung disease, equivocal results are less common and it is not usually necessary to go further than the lung scan. In the presence of chronic lung disease such as chronic obstructive pulmonary disease (COPD) or significant asthma, the ventilation–perfusion lung scan is more likely to be equivocal and further tests are more often used. In this case a computed tomography (CT) pulmonary angiogram was carried out. This showed a filling defect typical of an embolus in the right lower lobe pulmonary artery.
A search for a source of emboli with a Doppler of the leg veins may help in some cases, and the finding of negative D-dimers in the blood makes intravascular thrombosis and embolism unlikely.
Immediate management should involve heparin, usually as subcutaneous low-molecularweight heparin. The anticoagulation can then transfer to warfarin, continued in a case like this for 6 months. Alternative modes of contraception should be discussed and advice given on alternating walking or other leg movements with her seated periods at work. Thrombolysis should be considered when there is haemodynamic compromise by a large embolus.
• In the presence of a normal chest X-ray and no chronic lung disease, the ventilation–perfusion lung scan has good sensitivity and specificity.
• The chest X-ray and ECG are often unhelpful in the diagnosis of pulmonary embolism.
• CT pulmonary arteriogram is used when ventilation–perfusion scanning is likely to be unhelpful.