Investigation of suspected acute - PowerPoint Presentation

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Investigation of suspected acute pulmonary thromboembolism (PTE)Internal Medicine Society of Australia and New Zealand

Hugh

Patient medical history (PMHx) 48 year old male plumber ex-smoker (1 pack of cigarettes per day for 10 years) having ceased 6 months previously

mild chronic obstructive pulmonary disease (COPD) medications; regular Spiriva inhaler and Ventolin inhaler as requiredno recent illnesses, weight loss, calf pain or long-haul plane flightsSymptoms10 days ago he developed a bad head cold with runny nose and sore throat, followed by onset of a hacking cough productive of purulent sputum and shortness of breath on exertion.

After 4 days, he went to his GP and was prescribed antibiotics. His symptoms were improving until today when he suddenly developed sharp pleuritic chest pain adjacent to his left mid-sternum and worsening shortness of breath.Because the pain was severe and he was unable to go to work, he took himself to the local hospital ED for assessment

Hugh Examination

no feverpulse rate (PR) 60 bpmblood pressure (BP) 140/80 lying supine position, 125/70 standingnormal heart sounds with no murmurs

scattered coarse inspiratory crackles and mild expiratory wheeze heard over all lung zones with no friction rubmarked tenderness over the left 4th anterior costochondral jointabdominal and neurological examinations are normalno calf swelling or tenderness

Tests / Investigationsfull blood count and 20-item biochemical profile normalelectrocardiograph normalchest X-ray shows mild hyperinflation of both lungs with no other focal abnormalities

pulse oximetry shows normal arterial oxygen saturation of 96% on room air.

Hugh What is the diagnosis?

Viral or cough-induced costochondritis?Acute pulmonary thromboembolism (PTE) with clots passing to his lungs?

Need to rule out acute pulmonary thromboembolism (PTE) due to severity of the condition.

What investigations can be used for suspected acute pulmonary thromboembolism?

Duplex ultrasound of the lower limb veins

Imaging test used to demonstrate venous thrombi which, if located in the deep venous system, can embolise to the lungs.EchocardiographyImaging test to assess right ventricular function and measure right heart pressures in acute PTE.

Serum troponin assayBlood test to detect elevated troponin levels resulting from right heart strain in acute PTE or myocardial ischaemia resulting from decreased cardiac output in massive or sub-massive PTE.

D-dimer assay

Highly sensitive test to detect breakdown products of venous thrombi in the bloodstream.

Computerised

tomography pulmonary arteries (CTPA)Imaging test requiring contrast infusion which can detect

embolised thrombi in pulmonary arteries in patients with suspected PTE.

Hugh

Which investigations are recommended in this case of suspected acute pulmonary thromboembolism (PTE)?Duplex ultrasound of the lower limb veins

EchocardiographySerum troponin assay

D-dimer assayComputerised tomography pulmonary arteries (CTPA)

Hugh

Use a validated prediction tool such as the modified Wells score to guide choice of investigation. Modified Wells score includes variables such as ‘symptoms and signs of DVT’ and heart rate >100 bpm, where a score < 4 makes acute PTE unlikely.

For Hugh, the modified Wells score is 0. This indicates low pre-test probability of acute PTE.As a result, the recommendation for investigation for Hugh is:Duplex ultrasound of the lower limb veins

Echocardiography

Serum troponin assay

D-dimer assay

Computerised

tomography pulmonary arteries (CTPA)

Hugh

Correct steps for managementD-dimer assay yields a result of 300 ng/ml which, for Hugh, is below upper normal age-adjusted reference value (or cut-point) of 550 ng/ml. This result renders the probability of acute PTE < 1% (

ie very unlikely).No further investigations for acute PTE are recommended for Hugh.History and examination suggests costochondritis induced by prolonged coughing or viral infection as the most likely cause for Hugh’s presentation.

Hugh is treated with: 1) analgesics 2) local anaesthetic injection to his costochondral joint 3) discharged from ED with follow-up from his GP.

Choosing Wisely Australia recommendationDon’t request computerised tomography pulmonary angiography (CTPA) as the first-choice investigation in patients with low risk of venous thromboembolism (VTE) by modified Wells score. Instead request

D-dimer and perform imaging only if levels are elevated, after adjusting for age

Internal Medicine Society of Australia and New Zealand

What is best practice?

The modified Wells score (see adjacent table) is a validated prediction rule for estimating pre-test probability of DVT or acute PTE. A low score (< 4)

equates to a low (< 10%) probability of DVT or PTE. The quantitative D-dimer assay is highly sensitive for DVT and acute PTE, such that a negative result (ie value below the upper normal reference value, after adjusting for age*) effectively rules out this condition in patients with low pre-test probability, as determined by the modified Wells score.

*Adjustment for age: for patients over age 50, upper normal reference value for the assay is multiplied by age/100In patients with modified Wells score < 4, D-dimer assay should be the first-choice investigation rather than CTPA or duplex venous ultrasound

Modified Wells score

Feature Points

Clinical signs and symptoms of DVT 3

PTE most likely diagnosis 3

Heart rate >100 beats per minute 1.5

Immobilisation at least three days or surgery

within past four weeks 1.5

Previous DVT or PTE 1.5

Haemoptysis 1

Malignancy treatment within six months or palliative 1

Total score is summation of all points assigned according to the presence of each feature listed

What is best practice?

Unnecessary use of CTPA has negative consequences of:

contrast allergyradiation exposureidentification of benign incidentalomas that may provoke further invasive investigationsidentification of isolated small sub-segmental emboli that do not account for the clinical presentation and whose natural history is unknown, but which may lead to commencement of anticoagulation which has not been shown to be of any benefit in such cases, and instead imposes risk of major bleeding

unnecessary costunnecessary delays in discharging very low risk patients from congested EDs

EvaluationHow likely is this Choosing Wisely recommendation to change your practice?

Not at allSomewhatSignificantlyExplain your reasoning

choosingwisely.org.auDecember 2019

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