History of presenting problem

Pain

Is the pain really pleuritic? Did it develop suddenly? Sudden pleuritic chest pain is most likely to be due to pulmonary embolus with pulmonary infarction or a pneumothorax. Sudden onset of a unilateral  chest pain/discomfort and breathlessness should make you think immediately of pneumothorax, particularly in a tall, thin ‘Marfanoid’ man.

What was the patient doing in the hours before and at the moment when the pain came on? Unaccustomed or vigorous activity, e.g. painting the ceiling, is likely to precipitate musculoskeletal pain.

Breathlessness

Was the breathlessness sudden? Sudden onset of breathlessness with tachycardia and light-headedness caused by hypotension are suggestive of substantial pneumothorax or major pulmonary artery embolism.

Was there any haemoptysis? Haemoptysis occurs because of pulmonary infarction and supports the diagnosis of pulmonary embolism.

Thromboembolitic risk factors 

Are there any risks of thromboembolism? In this case clearly the findings on rectal examination suggest the possibility of rectal tumour. Cancer is a risk factor for thromboembolic disease. Other risk factors are:

-previous thromboembolism

-recent surgery: particularly major abdominal, pelvic, hip or knee surgery

-immobility, e.g. long haul aeroplane flights

-pregnancy/puerperium

-thrombophilia: protein C, proten S or antithrombin III deficiency; factor  V Leiden mutation; family history of thromboembolism

-obstruction to venous flow (maybe present if their is local spread of  a tumour )

-smoking

-obesity

-age over 40 years

-homocystenuria

-HIV/AIDS (although last on the list, definetly not the least)

Fever

Has there been fever? It is probable that this woman has had a pulmonary embolus, but ask about fevers, sweats or rigors. Most patients with pulmonary embolism are feverish, but high fever ( T> 38.5C), sweats or rigors make the diagnosis of pneumonia more likely.

Contraindications to anticoagulation

It is unlikely that this woman will have any contraindications to anticoagulation, but ask about these, the most common being a history of gastrointestinal bleeding. It is  probable that you would decide to anticoagulate someone proven to have pulmonary embolism, but in the presence of relative contraindication you would advise particularly close monitoring and counsel the patient to report problems immediately, e.g. change in colour of bowel motions, feeling of dizziness.

Examination

Full general, respiratory and cardiac examinations are required, but in this case pay particular attention to the following aspects.

General 

Is the patient seriously ill? Does the patient need resuscitation of airway, breathing and circulation? If yes, resuscitate and seek immediate help from intensive care.

If the patient is gravely ill, note respiratory rate (tachypnoea is defined as a respiratory rate >20/min) and look for central cyanosis. Is there any evidence of metastatic spread (nodes)?

Cardiovascular

There should be particular emphasis on signs of acute pulmonary artery obstruction and/or pulmonary hypertension, which would be likely to be caused by subacute or chronic pulmonary embolism in this case:

-tachycardia

-hypotension

-elevated JVP

-right ventricular heave (along the left sternal border)*

-loud P2 and right ventricular S3.* (*features more typical of pulmonary hypertension.)

For the pathophyisiology of the above click here.

Respiratory 

Respiratory may be entirely normal, but listen carefully for pleural rub. This can be very localized: ask the patient to put a finger on the spot that hurts most and listen carefully at and around that point. Consolidation typically gives bronchial breathing and dullness to percussion.

Musculoskeletal 

Can the pain be reproduced by any movement or by localized pressure? If it can then supports a musculoskeletal cause of pleuritic pain. However , remember that pleurisy is exacerbated by anything that causes pleural movement. If in doubt assume pulmonary embolism: be safe and not sorry.

Approach to investigation

Investigations  

Chest radiograph

This will helpexclude other  causes of pleuritic chest pain (pneumonia, pneumothorax)  and in resource limited setting, it may be the only imaging available. It may be normal, but most times there maybe changes (click here)  and these are as follows:

-Atelectasis

-linear infiltrates

-segmental collapse 

-raised hemidiaphragm

-pleural effusion

-Westermark’s sign (which is the asymmetry of lung markings due to absence of perfusion distal to a clot).  IMAGE

-Hampton's hump (a pleural-based wedge-shaped infiltrate/atelectasis from an infarct) IMAGE

-Palla's sign (an enlarged right descending pulmonary artery ).

Seek help from a radiologist to interpret x-rays when you can!

Electrocardiogram

Classic abnormalities include sinus tachycardia; new-onset atrial fibrillation or flutter; and an S wave in lead I, a Q wave in lead III, and an inverted T wave in lead III (SIQ3T3 seen in fewer than 10% of proven PE). Often, the QRS axis is greater than 90°. T-wave inversion in leads V1 to V4, perhaps the most frequent but least publicized change, reflects right ventricular strain. Abnormal ECG   Normal ECG  

Arterial blood gases

Respiratory alkalosis and hypoxemia are common findings,  but they should not be used in isolation to detect PE. ( Data from the Prospective Investigation of Pulmonary Embolism Diagnosis [PIOPED] indicate that, contrary to classic teaching, arterial blood gases lack diagnostic utility for PE, even though the PO2 and PCO2 will often both decrease. Among patients suspected of PE, neither the room air arterial PO2 nor calculation of the alveolar-arterial oxygen gradient can reliably differentiate or triage patients who actually have PE at angiography.)

Although ABG findings should not be used to confirm a diagnosis of PE, profound hypoxemia without clear explanation should raise suspicion for possible PE.

Plasma D-dimer

D-dimer is a breakdown product of cross-linked fibrin and is elevated in active venous thromboembolism. A normal value can be used to exclude thromboembolism. The enzyme-linked immunosorbent assay (ELISA) is more accurate than the rapid latex test. In case of D-dimer ELISA a value>500ng/mL is highly suggestive. Check with the your lab as to what method they are using, the reference range maybe different. (click)

D-dimer levels are not reliable in hospitalized patients as there are other causes of raised levels e.g. sepsis.

Echocardiography

More than half of patients with PE will have normal echocardiograms. Nevertheless, this imaging test helps with the rapid triage of extremely ill patients who may have PE. Bedside echocardiography can usually reliably differentiate among illnesses that have radically different treatment, including acute myocardial infarction, pericardial tamponade, dissection of the aorta, and PE complicated by right heart failure. McConnell's sign, i.e., right ventricular free wall hypokinesis with normal right ventricular apical motion, appears to be specific for PE. Detection of right ventricular dysfunction due to PE helps to stratify the risk, delineate the prognosis, and plan optimal management.              

Other findings on ECHO: are right ventricular dilatation, pulmonary artery enlargement, tricuspid regurgitaion, abnormal septal movement, and failure of the inferior vena cava to collapse during inspiration.

Specific tests for pulmonary embolism

Ventilation-perfusion isotope scanning

Small particulate aggregates of albumin labeled with a gamma-emitting radionuclide are injected intravenously and are trapped in the pulmonary capillary bed. The perfusion scan defect indicates absent or decreased blood flow, possibly due to PE. Ventilation scans, obtained with radiolabeled inhaled gases such as xenon or krypton, improve the specificity of the perfusion scan. Abnormal ventilation scans indicate abnormal nonventilated lung, thereby providing possible explanations for perfusion defects other than acute PE. The scans are interpreted as being normal, or of low, intermediate or high probability: reports need to be interpreted in the clinical context.

Pulmonary angiography

It is regarded by some as the ‘gold standard’ for diagonising pulmonary embolism, but is invasive-with major or fatal complications in 0.5-1.3% of investigations, and minor complications in 2%-and interpretation is not always straight forward, particularly for those who donot perform the test regularly. The most common finding is filling defect in the pulmonary artery as the radio-opaque dye flows around the embolus.

In the current era of chest CT with contrast, pulmonary angiography is reserved for

(1) patients with technically inadequate CT scans,

(2) scans performed on older machines that cannot image fourth- and fifth-order pulmonary arteries, and

(3) patients who will undergo interventions such as catheter embolectomy or catheter-directed thrombolysis.

Spiral computer tomography

This can detect intravascular clot from the pulmonary trunk down to the segmental arteries, but unlike pulmonary angiography it cannot visualize emboli in the subsegemental arteries. In many centres, this has become the investigation of choice, particularly for patients with pre-existing lung  disease, which renders the interpretation of ventilation-perfusion scans difficult or impossible.

Investigations relevant to the rectal mass

I’m sure you almost forgot about it, but no worries mate, most cases of PE will not have a rectal mass. Anyhow, in this particular case appropriate investigation would include sigmoidoscopy and biopsy.

Approach to Management

Please note that although pulmonary embolism has been discussed separately it is not a disease on its own.  Up to 40% of patients with deep venous thrombosis (DVT) actually have undiagnosed pulmonary embolism the  2 conditions therefore are best looked at together (Venous thromboembolic disease). Pulmonary embolism is a complication of DVT therefore, manage them together.

-ABCs; if in shock administer high flow oxygen, intravenous fluids, and immediately seek intensive care help.

-The use of warfarin and heparin should follow set hospital guidelines.(Click here for a set of Guidelines at my hospital).

-Pulmonary embolectomy is now reserved for patients who donot respond to thrombolysis or who have a contraindication to thrombolysis. Active bleeding from a rectal tumour would be a contraindication in our 54 yr old lady.

-Inferior  vena caval filters should be considered in patients at high risk of emboli in whom anticoagulation is a contraindication and in those with recurrent embolism despite adequate anticoagulation. (click here for HIV patients requiring an IVC filter)

Summary

In cases of acute onset chest pain, dypsnoea or unexplained hypoxemia, consider pulmonary embolism as one of your differentials. Remember if you don’t think about it you will miss it.

In the history, thromboembolitic risk factors should be explored.

The ideal approach to investigations is screen with D-dimer if >500 request a V/Q scan or helical CT scan if available.

In resource limited settings,  a  Chest x ray coupled with a good history and examination maybe all you’ve got-use them.

Familiarize yourself with local hospital guidelines for the management of venous thromboembolitic disease, more importantly, understand the rationale and mechanism of action of various therapy.

References 

1. Harrison’s online -  Pulmonary thromboembolism,  Dennis L. Kasper, Eugene Braunwald, Anthony S. Fauci, Stephen L. Hauser, Dan L. Longo, J. Larry Jameson, and Kurt J. Isselbacher, Eds

2. Current diagnosis and treatment in pulmonary medicine,   Michael E. Hanley and Carolyn H. Welsh.

3. Medical masterclass- Cardiology and Respiratory Medicine, John D Firth Michael I. Polkey, Paul R. Roberts.