A filter used to block clots from passing from the veins in
the legs to the arteries of the lung does not improve mortality rates for most
patients suffering a pulmonary embolism. However, if a patient is unstable – in
shock or requires a ventilator – filters can save lives.
Furthermore, for unstable patients with a pulmonary
embolism, it is crucial they receive clot-dissolving medications known as
The findings come from a set of three research articles on
pulmonary embolism treatment published by Michigan State
University’s Paul Stein
in the May edition of the American Journal of Medicine. The findings are based
on a study of more than two million patients suffering from the sometimes
deadly clots that travel to the lungs and block arteries.
Stein said the studies provide clearer guidance on what
treatments are most effective for patients, specifically in regard to vena cava
filters and thrombolytic therapy.
“There has been an increase in the use of vena cava
filters in the past several years for patients who arrive at a hospital
suffering from a pulmonary embolism,” said Stein, a professor in
osteopathic medical specialties and also director of research at St. Mary Mercy
Hospital in Livonia, Mich.
“But it appears the vast majority of filters that are
placed in patients with pulmonary embolism may not reduce mortality.”
However, he stressed that for the small proportion of
patients who arrive at a hospital in an unstable condition, the data suggest
mortality can be greatly reduced with a filter.
“These studies provide strong evidence on when filters
reduce mortality and when they will not,” he said. “Only a small
percentage of patients suffering from a pulmonary embolism are in shock or in
need of ventilation support, and therefore only a small proportion need a
Stein said for unstable patients it is vital that in
addition to using a filter, they receive thrombolytic therapy, which is much
less of a risk than the surgical removal of a clot known as an embolectomy.
“Only about a third of unstable patients receive
thrombolytic therapy,” he said. “The reason may be doctors are afraid
that patients will suffer from excessive bleeding. But the data show
thrombolytic therapy would save lives if used more frequently.”
As for an embolectormy, Stein’s team found that in most
surgical centers, unless the clinicians are highly specialized and experienced,
the mortality rate is high. In most hands, he said, thrombolytic therapy would
save more lives.
The findings were from a nationwide government database, the
Nationwide Inpatient Sample, and included data on more than two million
patients who suffered a pulmonary embolism between 1999 and 2008.