From February 1989 to November 1992, 61 Bird's Nest filters were placed in the infrarenal vena cava in 61 patients (36 men and 25 women; mean age ± s.d., 63 ± 15, range (16–83). In 27 (44.3%). the filter was inserted because of contraindication to anticoagulation, in 19 (31.1%) for anticoagulation failure and in 15 (24.6%) as prophylaxis against pulmonary embolism in high risk patients. All the filters were introduced by percutaneous puncture of the femoral vein after preliminary screening venography demonstrated that the iliac vein was free of thrombus. Two deaths occurred within 24 h of filter placement (periprocedure mortality 3.3%) while five other patients died within 1 month (30 day cumulative mortality 11.5%). At follow up, 2–40 months later (mean ± s.d., 17 ± 9), a further 13 patients had died (cumulative mortality 32.8%). At 36 months, the probability of survival, calculated by the Kaplan‐Meier Product Limit Method, was 55% (95% confidence intervals 37–74%). Apart from the two patients dying within 24 h, none of the early or late deaths were attributable to the procedure and there were no recurrent pulmonary emboli. Thirty‐seven of the surviving 41 patients were recalled for clinical examination and Duplex ultrasound interrogation of the vena cava and the lower limb veins. No new venous thromboses in the legs were observed and no increase or onset of leg swelling was reported. The vena cava patency was 100% in these 37 patients. Considering that the annual attack rate for deep venous thrombosis in New South Wales, Australia is 60 per 100000, and for pulmonary embolism 45 per 100000, vena caval filter placement is an effective but underused resource.
In patients with venous thrombotic disease and in whom anticoagulation or thrombolytic therapy is inappropriate, ineffective, or even contraindicated, insertion of vena caval filters or venous thrombectomy must be considered. The primary indication for the placement of vena caval filters is in patients who have developed a pulmonary embolus and in whom anticoagulation is either contraindicated or in whom anticoagulation must be discontinued because of the development of bleeding complications. At the present time, either the Greenfield filter placed through a jugular, femoral, or axillary venotomy or the bird's nest filter are appropriate and appear to be the most effective and least fraught with complications. The use of venous thrombectomy has waxed and waned over the last several decades. At the present time, the procedure is advocated mainly for lower limb venous thrombosis which is extensive enough to threaten limb viability. On occasion, it may be appropriate to extend the indications for venous thrombectomy to include femoral thrombosis of less than 10 days duration or iliac thrombosis of less than 3 weeks duration with floating thrombi at the level. Technical modifications which improve the patency of the obliterated veins which are predisposed to rethrombosis include the creation of a temporary arteriovenous fistula and meticulous care in removing the entire clot. The patient should be treated with anticoagulants postoperatively to prevent a recurrence of the problem. The main theoretical advantage of venous thrombectomy is a reduced incidence of postthrombotic syndrome. Objective data to support this contention do not exist.
Large tissue defects may occur following head and neck surgery. When combined with ipsilateral radical neck dissection the venous drainage of a free flap used to cover the defect may be compromised. Twelve patients having radical neck dissections underwent on-table venography to study the pattern of venous drainage of these flaps. The predominant drainage pattern is initially in a cephalic direction, then across the midline and finally in a caudal direction on the contralateral side of the neck. Venous drainage to the contralateral side of the neck may be a determinant of flap survival. In order to facilitate venous drainage following free flap procedures, patients should be positioned so that the contralateral internal jugular vein is not compressed. Drains should be placed caudal to the microvascular anastomoses in order to minimize interference with the cephalic direction of venous drainage. Any patient having a radical neck dissection requiring a central venous catheter should have it placed ipsilateral to the neck dissection. Thrombosis around a contralaterally placed cannula may significantly increase head and neck venous pressure.
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