Physicians have been taught to recommend bedrest in patients with acute venous thromboembolism during the initial two to four days of treatment. However, bedrest is not recommended in the American College of Chest Physicians guidelines for treating acute venous thromboembolism. The bedrest recommendation was based on the assumption that movement may dislodge the clot and cause a fatal pulmonary embolism (PE). This assumption has never been evaluated systematically to determine whether it is accurate. Three small trials found no difference in morbidity or mortality in patients with deep venous thrombosis (DVT) who were assigned to bedrest versus those who were allowed to ambulate. There are no studies that evaluate this issue in patients with PE. Trujillo-Santos and associates evaluated clinical outcomes in patients with venous thromboembolism assigned to strict bedrest versus those who were allowed to ambulate.

Participants in the study were patients with symptomatic, acute DVT or PE confirmed by an objective test. Those who met these criteria were enrolled in a national data bank. Patients were excluded if they had any contraindication for ambulation. Immobilization was defined as total bedrest to limit activity for up to three days. The study period was the first 15 days after the diagnosis of DVT or PE was established. The primary outcome was the development of symptomatic, objectively confirmed PE after initiation of treatment. Secondary outcomes included development of bleeding complications and death.

There were 2,650 patients enrolled in the study; 2,038 had acute DVT and 612 had PE. Of the patients with DVT, 1,050 were allocated to bedrest during the study and 988 were allowed to ambulate. Of the patients with PE, 385 were assigned to bedrest and 227 to ambulation.

Eleven patients with DVT and four with PE developed new symptomatic PE after treatment was started. These were confirmed with diagnostic studies. Five of these patients died as a result of the new PE (four with DVT and one with initial PE). The two most common risk factors for developing PE after treatment was started were age younger than 65 years and comorbid diagnosis of cancer. Comparing bedrest with ambulation groups, the researchers found no significant difference with regard to new PE events, fatal PE, or bleeding complications.

The authors conclude that bedrest has no impact on the risk for developing new PE in patients with acute DVT or PE. The risk of developing PE after starting treatment was low but was associated with a significant mortality rate.