A 75-year-old with abdominal pain, hypoxia, and weak pulses in the left leg
RISK STRATIFICATION IN ACUTE PULMONARY EMBOLISM
Multiple models exist to estimate the risk of complications in patients with acute pulmonary embolism.
The Bova score6 is based on the following factors:
- Systolic blood pressure 90–100 mm Hg (2 points) (patients with systolic blood pressure lower than 90 mm Hg were excluded from the study from which this score was derived)
- Cardiac troponin elevation (2 points)
- Right ventricular dysfunction on echocardiography or computed tomography (2 points)
- Heart rate 100 beats/min or greater (1 point).
A total score of 0, 1, or 2 (stage I) denotes low risk, 3 or 4 points (stage II) intermediate risk, and more than 4 points (stage III) high risk.
The PESI score (Pulmonary Embolism Severity Index)7 is based on:
- Age (1 point per year)
- Sex (10 points for being male)
- Heart rate 110 per minute or greater (20 points)
- Cancer (30 points)
- Heart failure (10 points)
- Chronic lung disease (10 points)
- Systolic blood pressure less than 100 mm Hg (30 points)
- Respiratory rate at least 30 per minute (20 points)
- Temperature less than 36ºC (20 points)
- Altered mental status (60 points)
- Arterial oxygen saturation less than 90% (20 points).
The total score is broken down into 5 classes: I (< 65 points), II (65–85), III (86–105), IV (106–125), and V (> 126). Classes I and II are low risk, and the higher ones are high risk.
The simplified PESI score8 was developed to more rapidly risk-stratify patients and has been found to be similar to the PESI score in prognostic accuracy. Patients get 1 point for each of the following:
- Age over 80
- Cancer
- Chronic cardiopulmonary disease (heart failure or chronic lung disease)
- Heart rate 110 per minute or greater
- Systolic blood pressure less than 100 mm Hg
- Arterial oxygen saturation less than 90%.
A total score of 0 is low risk; anything higher is high risk.
Back to our patient
Our patient had proximal and calf deep vein thrombosis of the right leg, bilateral submassive pulmonary emboli with associated biomarker elevation and right ventricular dysfunction, and left renal artery thrombosis with infarction. Using the PESI score, his risk of death in the next 30 days was 13.7% and his 30-day risk of a complicated course was 27%. Using the Bova score, his 30-day risk of death was 15.5% and his 30-day risk of a complicated course was 29.2%.6,7
Notably, the patient’s right ventricular function had also been impaired on the echocardiogram performed during his admission 1 month previously. On transthoracic echocardiography during the current admission, the patient was found to have a similar degree of right ventricular dysfunction. This finding, along with the oxygen requirement that developed during the earlier admission, suggested that his pulmonary embolism may have been subacute and that the diagnosis may have been missed during the earlier hospital stay.
The patient was treated with unfractionated heparin. After the hospital’s multidisciplinary pulmonary embolism response team discussed and weighed the above factors, they recommended to not pursue thrombolytic therapy or inferior vena cava filter placement.
Of note, the patient’s pulses in the left lower extremity continued to be weak but palpable, and the left leg was cooler to touch than the right leg.
ASSESSING PERIPHERAL ARTERY DISEASE
4. How should the finding of weak pulses in this patient’s left leg be initially investigated?
- Computed tomographic angiography with runoff
- Ankle-brachial indices with pulse-volume recordings
- Arterial duplex ultrasonography
- Magnetic resonance angiography of the lower extremities
The ankle-brachial index is the initial diagnostic test for assessment of pulse abnormalities and for diagnosis of lower-extremity peripheral artery disease. It is calculated by dividing the higher of the ankle systolic pressures (posterior tibial or dorsalis pedis) by the higher of the 2 brachial pressures (left or right).9 Normal values are between 1.00 and 1.40.
Ankle-brachial indices in our patient
Our patient underwent measurement of his brachial, dorsalis pedis, and posterior tibial artery systolic pressures using blood pressure cuffs and continuous-wave Doppler. Ankle pulse-volume recordings were also obtained.
Given the patient’s poor renal function and concern for acute renal infarction, we thought it best to avoid iodinated or gadolinium contrast, such as with magnetic resonance or computed tomographic angiography.
Segmental leg pressures and pulse-volume recordings can be performed to help localize the level of arterial disease in the extremities, but were not done in this case because of the extensive deep vein thrombosis in the right leg.10,11
Arterial ultrasonography in our patient
Arterial duplex ultrasonography was performed to help determine the location of arterial disease. It showed patent arteries in the right leg. In the left lower extremity there was slow, monophasic blood flow in the distal superficial femoral artery. The popliteal artery was occluded. The posterior tibial artery was occluded at the origin, with reconstitution distally. The peroneal artery was occluded throughout. The anterior tibial artery was patent throughout. The ultrasonographic findings were thought to be suspicious for arterial thromboembolism.
