Today many patients with cancer have indwelling long-term central venous catheters. Benefits from catheter use include increased ease of administration of either chemotherapy or other drugs. However, these patients are prone to a number of complications, including deep venous thrombosis (DVT) and infection. Two kinds of catheter-related thrombi may develop: sleeve thrombi developing on the outside of intravenous catheters and occlusive DVT. Recent studies have demonstrated that the prevalence of pulmonary embolism in patients with arm DVT is high, and it is close to that observed in cohorts of patients with lower-extremity DVT. Accordingly, some kind of prophylaxis seems to be warranted. Furthermore, patients with confirmed catheter-related DVT should receive long-term anticoagulant therapy.

Summary Background: Asymptomatic pulmonary embolism (PE) is a common finding in patients with deep venous thrombosis (DVT) of the lower limbs, but the usefulness of seeking for silent PE in patients with acute DVT has not been evaluated. Patients and methods: This was a prospective study involving consecutive patients with acute symptomatic proximal DVT (confirmed by objective methods) and no clinical suspicion of PE. All patients underwent chest X-ray, ventilation-perfusion lung scan and arterial blood gases on admission, and received anticoagulant therapy. Those with scintigraphic evidence of PE underwent repeated lung scan and blood gases 7 days later. The aim of the study was to assess how many patients with silent PE develop symptoms while on heparin therapy, and in how many of them such symptoms are due to recurrent PE. Results: 946 consecutive patients with acute, proximal DVT had no contraindications to full-dose anticoagulant therapy. Baseline lung scan revealed high-probability defects (silent PE) in 200 (21%). Seven of these 200 patients had symptomatic recurrences during the 7-day study period, and an inferior vena cava filter was inserted. Besides, 6 patients developed PE symptoms, but no new perfusion defects were found on repeated scan. They switched to coumarin therapy, and they did not develop any further complications. Conclusions: Lung scan in patients with symptomatic DVT and no clinical suspicion of PE may be useful, since some patients with silent PE may develop symptoms while on heparin therapy. Without a baseline scintigraphy all these patients would have been considered to have recurrent PE, and vena cava interruption could have been performed.

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