COVID-19 Pulmonary Embolism Often Seen Outside the ICU

Cyclomedica Australia PTY LTD

Cyclomedica manufactures medical equipment for nuclear medicine lung imaging. Cyclomedica's core product is Technegas™.

The Technegas™ system is a device which creates Technegas™; an ultra-fine dispersion of Tc99m labeled carbon used for nuclear medicine ventilation/ perfusion (V/Q) lung imaging. V/Q imaging is used to diagnose pulmonary embolism.

Technegas has been on the market since 1984 and since then over 4 million patient exams performed. Technegas™ is not yet available in the United States.

Technegas offers significant advantages over all other V/Q agents because it behaves as a true gas allowing its nano-sized particles to penetrate deep into the alveoli where they remain bound to the lining of the alveoli resulting in a very stable, true functional image of the highest quality. Showing a higher sensitivity and specificity result over traditional planar V/Q, Technegas™ is considered the agent of choice for quality SPECT-VQ in the asseesment and follow up for PE, and more recently, in the evaluation of COPD and other airways disease.

Technegas™ SPECT-VQ has shown to have the same sensitivity as CT- Pulmonary Angiograms (CTPA) with much less radiation burden to the patient and has become a standard of care for lung imaging in Nuclear Medicine.

COVID-19 Pulmonary Embolism Often Seen Outside the ICU

Acute pulmonary embolism (PE) was common in COVID-19 cases, often in obese patients and in those not sick enough to require critical care, an observational study showed.

PE turned up in 22% of 328 patients who got pulmonary CT angiography for PCR test-positive COVID-19 at the Henry Ford Health System's hospitals in Detroit from March 16 to April 18.

Notably, 51% of the PE cases were diagnosed in the emergency department and 72% overall were diagnosed in patients who did not require intensive care unit (ICU) level care, reported Neo Poyiadji, MD, of the Henry Ford Hospital in Detroit, and colleagues in Radiology.

While the overall PE rate was in line with the 23% to 30% rate in other studies within computed tomography (CT) angiography-tested populations with COVID-19, the proportion of non-ICU cases was "in sharp contrast to a recently published study highlighting PE to be associated with ICU admission and mechanical ventilation," the group wrote.

ICU admission was not more common in the PE group in their study, nor was rate of intubation in those who were admitted to the ICU (65% vs 67% without PE, P=0.89).

"Our results suggest that even patients who do not have severe enough illness to qualify for ICU care can develop acute pulmonary embolism," the researchers concluded.

Abnormally aggressive coagulation has been noted with COVID-19, and consensus has formed for thromboprophylaxis during admission, despite some disagreement on the specifics.

Guidelines from a consensus group of the International Society on Thrombosis and Haemostasis and other professional societies recommended risk stratifying COVID-19 patients in the hospital for venous thromboembolism (VTE) prophylaxis using the normal risk tools. Other groups have recommended prophylactic-dose low molecular weight heparin for all hospitalized COVID-19 patients, even those not in the ICU, irrespective of risk scores.

In the study, 28 of the 122 (23%) patients that were on venous thromboprophylaxis developed a PE.

Recent autopsy studies in the Annals of Internal Medicine have suggested that more thrombotic events may be happening than clinically detected.

Autopsy of the first 12 COVID-19 deaths in one area of Germany turned up unsuspected deep venous thrombosis in seven (58%) and PE as the direct cause of death in four.

A series from Austria on 11 deceased patients with COVID-19 (10 of whom were selected at random for autopsy) showed that, while VTE was not clinically suspected before death in any of the patients, all had thrombosis of small and mid-sized pulmonary arteries to various degrees. Ten of the 11 received prophylactic anticoagulant therapy.

In the study by Poyiadji and co-authors, other predictors of PE were elevated D-dimer and obesity.

Body mass index greater than 30 was more common in the PE group than in the non-PE patients (58% vs 44%, P=0.05), with obesity associated with a significant 2.7-fold higher risk after adjustment for other factors.

A 6-μg/mL increase in D-dimer had a multivariate odds ratio of 4.8 for PE (P=0.001). D-dimer at 3.11 μg/mL predicted PE with 78% sensitivity and 81% specificity.

However, statin therapy prior to admission was associated with a 60% lower likelihood of PE in the multivariate model (P=0.005). "Statins have been previously described to be associated with decreased rates of venous thromboembolism, as well as to decrease the risk of recurrent PE," the researchers noted.

Limitations of the study included the retrospective, single health system design, the authors said. Also, the findings should not be extrapolated to all COVID-19 patients, Poyiadji suggested.

"It is difficult to say what proportion of COVID-19 patients underwent pulmonary CT angiography," Poyiadji told MedPage Today. "From the time frame of our study, approximately 2,500 COVID-19 patients were admitted to our hospitals within our system. However, there are many more COVID-19 patients who were not admitted ... Patients who underwent pulmonary CT angiography had either intermediate or high probability for PE. It is not a routine scan for COVID-19 patients."