Sat27November0556PM 20

A 73-year old man is admitted to the intensive care with hypoxic ventilatory failure six days after a total hip replacement. He is sedated, intubated and ventilated. The SpO2 is 92% on 60% oxygen but haemodynamically stable.

Which of the following investigations will best confirm a diagnosis of an acute pulmonary embolism?

(Please select 1 option)

V/Q scan

12-lead ECG

CT Pulmonary angiography (CTPA) Correct

Chest X ray

Transthoracic echocardiogram

Explanation

CT Pulmonary Angiography (CTPA) in the Radiology department or imaging suite is the preferred diagnostic imaging modality in patients who are being mechanically ventilated in the Critical Care Unit where pulmonary embolism (PE) is suspected. The sensitivity and specificity of this investigation is high at 83% and 96%, respectively.

If a patient is haemodynamically unstable the risks of transportation to a remote area are high, a bedside diagnostic test such as echocardiography is more appropriate. This investigation is a rapid bedside diagnostic tool, which may be useful if the use of thrombolytic therapy or embolectomy is being urgently considered.

A 12-lead ECG is usually abnormal in massive PE due to acute right ventricular failure, possibly in combination with hypoxaemia, but the findings are neither sensitive nor specific.

A chest X ray cannot be used to confirm the diagnosis of PE and should only contribute to the diagnostic approach by ruling out conditions that mimic pulmonary emboli in the ICU, such as atelectasis, pulmonary oedema, pleural effusions, pneumonia and pneumothorax

V/Q-scanning is impractical in the intensive care setting as it can only be considered when the CXR is normal and there is no concurrent cardiopulmonary disease.

The usefulness of measures of D-dimer, troponin and B-type natriuretic peptide as diagnostic tests in critically ill patients with clinically suspected PE is limited.

Answer Statistics

1

2%

2

1%

3

97%

4

2%

Times answered: 312