PURPOSE: CT pulmonary angiogram (CTPA) is the gold standard for the diagnosis of pulmonary embolism (PE). Indiscriminate use of CT scans results in unnecessary exposure to ionizing radiation. Ultrasound can diagnose venous thromboembolism indirectly and can aid in establishing an alternate diagnosis. We studied the accuracy of bedside ultrasound to predict the need for CTPA.
METHODS: Prospective study performed at a tertiary care hospital by pulmonary/critical care fellows and attendings trained in ultrasonography. When a CTPA was ordered patients had a screening ultrasound performed. (within 3 hours) All examiners were blinded to CTPA results prior to ultrasound exam. Ultrasound consisted of 3 parts: limited cardiac echocardiogram to evaluate left ventricular (LV) and right ventricular (RV) size and function; lung/pleural ultrasound to identify pneumothorax, alveolar consolidation, alveolar-interstitial pattern and pleural effusion; and deep venous thrombosis (DVT) study using two-site compression of the femoral and popliteal veins. We predicted no need for CTPA if either DVT was found with or without RV enlargement or clear evidence of an alternative diagnosis. We also compared our findings on ultrasound to formal DVT and echocardiographic studies, and CTPA parenchymal findings.
RESULTS: 82 ultrasound studies were performed. CTPA was completed in each case and 12/82 (14.6%) were positive for PE. Based on ultrasound findings, CTPA was not needed in 38/82 (46.3%) patients, all of which had CTPA studies negative for pulmonary embolism or positive for PE with positive DVT studies on ultrasound (7.8%). Fifteen (18.3%) patients had formal DVT studies and our results correlated in 15/15 (100%) patients. Formal echocardiography was performed in 28 patients (34.1%). Our findings correlated in 26/27 (96.3%) patients.
CONCLUSION: Point of care ultrasonography performed by a skilled physician can accurately predict the need for CTPA. An alternate diagnosis can be predicted when parenchymal abnormalities exist. DVT studies and point of care echo can also be accurately performed by skilled pulmonary/critical care physicians.
CLINICAL IMPLICATIONS: CT scans to diagnose pulmonary embolism can be reduced using ultrasonography to diagnose DVT’ s and provide alternative diagnosis.
DISCLOSURE: Seth Koenig, No Financial Disclosure Information; No Product/Research Disclosure Information