Rajah 1983.

Methods	RCT
Participants	Patients (n = 327) undergoing major thoracic surgery
Interventions	‐ Heparin 5000 IU subcutaneous ‐ Low‐dose heparin 2500 IU subcutaneous plus dihydroergotamine 0.5 mg subcutaneous ‐ No thromboprophylaxis Study treatment was given tid for 10 days after surgery
Outcomes	DVT. 125I fibrinogen uptake scan was used to diagnose DVT and all patients with a positive scan had a bilateral ascending venography to confirm the diagnosis
Notes	The type of thoracic surgery is not specified thus it remains unclear whether this study fulfils the inclusion criteria of the review