Duplex screening as a method of quality assurance of perioperative thromboembolism prophylaxis

Background. Improvements in thrombosis prophylaxis in both the operative an d non-operative fields aim to reduce further the not inconsiderable residua l risk of suffering a deep vein thrombosis or embolism. The goal of the stu dy was to establish the part played in a quality assurance strategy by earl y diagnosis of a thrombosis and by knowledge of the hospital's internal pat ient-risk profile in order to counter the unpredictability of thromboemboli c complications and make rational decisions about thromboembolism prophylax is. Methods. Duplex ultrasonography has been used routinely in trauma surgical patients in Krefeld Hospital since September 1991 as a screening method for diagnosing deep leg and pelvic Vein thrombosis prior to mobilisation of th e patients. 778 patients were investigated up to March 1997. In the period from September 1991 to September 1994, patients received standardised low-d ose prophylaxis with unfractionated heparin (UFH). In October 1994, the pro phylaxis regimen was modified by chan,ain,a the anti-embolism stockings fro m bidirectional elastic stockings to transverse elastic graduated compressi on stockings (TED(R)) and by adapting the dosage of the heparin prophylaxis to patient risk, with the use of low molecular weight heparin (LMWH) Certo parin (Mono-Embolex(R) NM) since April 1995. All patients with a deep vein thrombosis were treated immediately with APTT-monitored full heparinisation and immobilisation. Results. In the period from September 1991 to March 1997, an asymptomatic d eep vein thrombosis of the lower Limbs was diagnosed in 68 cases (8.7%) out of 778 trauma surgical patients by means of routine duplex ultrasound. Usi ng a strategy of duplex screening and immediate anticoagulation/immobilisat ion, no clinically significant pulmonary emboli occurred in this period. At the same time, the antithrombotic efficacy of the prophylaxis could be imp roved and assessed objectively by means of duplex screening: with optimal c ompression stockings and consistent use of risk-adapted UFH prophylaxis, it was possible to reduce the residual thrombosis rate, which was 11.5% (95% CI 7.7-15.2%) with standard UFH prophylaxis, to 8.7% (95% CI 4.5-12.9%) and ultimately, using the combination of optimal anti-embolism stockings and L MWH prophylaxis, to 6.0% (95% CI 3.0-8.9%) which was significant (p<0.05). The cost-effectiveness analysis resulted in a cost-relation per successfull y treated patient of about 1:100 for the diagnosis of a deep vein thrombosi s using duplex ultrasound and subsequent heparin treatment compared to the diagnosis and intensive care treatment of a massive pulmonary embolism. Conclusions. Duplex ultrasound screening for asymptomatic deep vein thrombo sis thus proves to be a suitable instrument for internal hospital quality c ontrol in thrombosis prophylaxis. Its routine use can be recommended at lea st in high-risk patients, not only from the medicolegal aspect but also fro m the purely economic aspect.