乌鸦传媒

SAN FRANCISCO -- Patients who experience tachycardia -- either symptomatic or asymptomatic -- following knee replacement surgery are most likely to trigger an imaging examination to determine if the patient has pulmonary emboli, researchers suggested here.

In a study of 457 patients who underwent computed tomography (CT) scans, 60.3% had a diagnosis of tachycardia that created an order for the imaging study, said , a fellow in pulmonary critical care medicine at New York University School of Medicine, in his poster presentation. About 24.7% of the scans were triggered by patients who experienced hypoxia, and 10.1% of the scans were performed because patients said they had shortness of breath.

Overall, 73 of these patients, or 15.9% of the cohort, were found to have pulmonary emboli, he told 乌鸦传媒 at the annual meeting of the American Thoracic Society, noting that the figure was lower than that in other reports in the literature.

Knee replacement procedures were observed to have the highest incidence of positive scans -- 56.2%. That represented 41 of the 73 patients who had positive scans during the time period of the retrospective study of May 2013 to April of 2015. Hip replacement surgery was the second most common incidence of positive scans, with 21.9% (16 patients). Spine procedures were third, with 13.7% (10 patients) testing positive. The remaining 8.2% of post-procedure pulmonary emboli were observed in upper extremity and foot and ankle procedures.

Of the 457 patients who had CT scans for suspected pulmonary embolism, 57 of these patients had undergone lower extremity duplex examinations, and the doctors diagnosed deep vein thromboses (DVT) in 1.7% of these individuals.

All patients undergoing total hip and total knee replacement also received pharmacological anti-coagulation with warfarin, low-molecular-weight heparin, or aspirin in accordance with the standard protocol for DVT prophylaxis at his institution, Postelnicu said. Arthroscopy, foot, ankle, and hand patients were not given anticoagulation therapy.

'We get many calls from our colleagues in the orthopedic specialty service that they have patients who are hypoxic or have shortness of breath or have tachycardia," Postelnicu said, in explaining why the study was conducted. "We wanted to determine the incidence of pulmonary embolism in our population and compare it with that of other hospitals in our area such as the Hospital for Special Surgery, which recorded an incidence of pulmonary embolism of almost 30% when patients had a CT scan."

The researchers wanted to determine how the incidence of pulmonary embolism in the patient population compared. He said the finding of a lower incidence of pulmonary embolism at his institution might be related to the ethnic makeup, noting that his patients were predominantly white -- 58.9%, with 21.9% self-reported as black -- while other hospitals had a more diverse population.

The study also showed that knee surgery patients were most likely to be diagnosed with pulmonary embolism, with just 22% of these complications observed among hip replacement surgeries. Postelnicu said other studies have a higher percentage of hip replacement surgery patients developing emboli.

"It sort of gets to the point where if you had knee surgery and all of a sudden you have shortness of breath, there is a very good chance you have a pulmonary embolism." he said. "That is pretty concerning."

Commenting on the study, , a fellow in pulmonary critical care at the University of Colorado Anschutz Medical Campus in Aurora, told 乌鸦传媒 that he didn't find these results surprising. "Whenever I would be called in to consult with the orthopedists on a patient who was having shortness of breath or tachycardia following surgery, I figured it was a pulmonary emboli.

"The first, second, and third things that cross my mind are pulmonary embolism. If this happens 15% to 16% of the time, as is shown in the study, that is a lot. Tachycardia can be subtle. It isn't necessarily something that is felt by the patient, but it will show up in vital signs or in monitoring.

"You have to treat these signs with urgency; pulmonary embolism can be fatal," he said.

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