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ABSTRACT AND COMMENTARY BY: Joseph
A.Caprini, M.D.
Director, Surgical Research
Northwestern University Medical Center, Chicago, Illinois
This paper reports the results of a questionnaire
sent to 363 surgeons of the Vascular Surgical Society of Great Britain and
Ireland about their use of deep vein thrombosis (DVT) prophylaxis at the time of
varicose vein operations. Eighty percent (80%) (289/363) of the questionnaires
were returned and only 29% (83/363) of the surgeons felt that varicose veins
were an important risk factor for DVT. Subcutaneous heparin therapy was used by
only 33% of those who felt that varicose veins were an important risk factor for
DVT. Heparin was used by a mere 12% of all surgeons responding.
Factors which influenced heparin use included previous DVT, obesity, age,
recurrent varicose veins, and inpatient status. Reasons for not giving heparin
included concern about bleeding or bruising, no evidence of DVT risk, rapid
mobilization, the perceived effectiveness of elastic compression, and the
feeling that one or two doses were not worth the effort. Other methods of
thrombosis prophylaxis included anti-embolism stockings, elastic bandages, leg
elevation, Dextran 70, cessation of smoking, and intravenous fluids. The types
of bandaging placed on the leg at the end of the varicose vein operation
included crepe or other bandages, uniform compression hose, and graduated
elastic compression hose (antiembolism). A small minority (4%) used heavier
hose. Antiembolism hose were used in the days following operation in 55% of
patients and 15% used other (perhaps heavier) hose.
The survey revealed that the majority of vascular surgeons in the United Kingdom
and Ireland do not believe that varicose veins are an important risk factor for
DVT. However, interest in this topic appears keen as evidenced by the 80%
response rate. The authors were surprised that more surgeons were not influenced
by obesity or bilateral procedures as risk factors in their selective use of
subcutaneous heparin.
The only factor influencing heparin use was a history of DVT. The authors
supported the practice of having multiple surgeons in order to decrease the
procedure time since this may influence the risk of DVT. They pointed out that
varicose veins are listed as a risk factor for DVT in national and international
consensus documents despite the paucity of Level 1 data on the subject. They
felt that medicolegal considerations prompt them (as well as some of the
respondents) to employ subcutaneous heparin in these patients. They also felt
that the duration of the operation should be short with more than one
experienced surgeon being desirable. Tilting the head down during operation,
passive calf movements by the operating team at the conclusion of the operation,
and early ambulation are all advised to minimize the incidence of DVT. The
authors also suggested subcutaneous heparin be used along with compression
therapy during the perioperative period when there is a history of venous
thromboembolism or oral contraceptive use.
Additional indications for this approach, according to the authors, included
other risk factors such as obesity, long operations, and advancing age. They did
not feel that the slightly increased risks of hematoma and bleeding warranted
the use of heparin in the absence of established risk factors mentioned above.
COMMENTARY
This paper reflects the clinical preferences of vascular surgeons in the United
Kingdom and Ireland and reflects the available medical literature concerning the
association, or lack thereof, between varicose veins and venous thromboembolism.
Unfortunately, this is an area where the truth is disguised due to the
prevalence of multiple risk factors, including varicose veins, in the same
patient as well as the lack of appropriate Level 1 studies addressing the
problem.
Recently, a report by B–hler, et al. prospectively evaluated thrombotic risk,
including the diagnostic significance of preoperative color-coded duplex
sonography in patients undergoing operations for varicose veins.1 Ascending
pressure phlebography (APP) and color-coded duplex sonography (CCDS) were done
before and 10 and 21 days following stripping operations for varicose veins. No
postoperative DVT occurred in patients investigated with these tests. The
authors concluded that the postoperative thrombotic risk following varicose vein
operations is low in properly selected patients. Their study included carefully
selected, healthy individuals without any history of venous thrombosis or
secondary varicosis due to the postthrombotic syndrome. They also stated that
CCDS was the preferred investigative tool because of the excellent correlation
with APP, providing a high degree of accuracy in the diagnosis of reflux and
regular vein morphology.
B–hler's work supports the opinions expressed by the vascular surgeons in the
survey. However, before this topic is closed, consider some additional factors
regarding varicose veins. The presence of visible leg varicose veins is usually
associated with reflux at one of a number of possible locations in the leg which
results in leakage of blood from the deep to the superficial venous system when
the calf muscle pump contracts to drive blood toward the heart. This phenomenon
is enhanced because of a pressure difference - 25 to 53 mmHg base pressure in
the deep venous system compared to 0 to 1 mmHg pressure under the skin where
varicosities are located. As the pressure increases in the muscle compartment,
blood can leak through perforating veins into the veins in the subcutaneous
space, engorging them with blood because of the low pressure. This causes
progressive dilatation of the surface veins, pulling venous valve cusps apart
and increasing the magnitude of the venous dilatation. Eventually, the surface
venous pressure will rise. The ensuing venous congestion can impair influx of
arterial blood, particularly at the capillary level. Therefore, some feel that
surface venous stasis and vein dilatation can be pathophysiologic factors in the
occurrence of venous thrombosis.
The use of leg compression hose of at least 30 to 40 mmHg can overcome the
pressure differences between the deep and superficial compartments. This results
in a decrease in the size of surface varicosities and a marked decrease in blood
pooling and stasis. Antiembolism hose and many leg wraps do not have sufficient
pressure to reverse these gradients. We feel that heavy hose is most valuable in
the management of patients with hemodynamically significant varicosities. The
hose are ideal for patients who refuse surgical therapy and those with multiple
risk factors which may be associated with a high risk for venous thromboembolism
if a surgery is done. We routinely use these stockings following operation,
usually applying them in the operating room and continuing them for several
weeks postoperatively. In our experience, postoperative pain and discomfort are
reduced using these hose.
We have reviewed our experience in 313 patients undergoing surgery for
varicosities under general or regional anesthesia over a five-year period.
Fourteen percent (14%) had prior superficial venous thrombosis in branches of
these varicose veins. All patients had graduated elastic stockings and
sequential pneumatic compression devices used perioperatively. Those with more
than four risk factors also received postoperative subcutaneous heparin for four
weeks. All patients wore 30 40 mmHg hose for two to four weeks postoperatively.
None developed venous thromboembolism.
We feel that careful assessment of thrombosis risk using a risk assessment guide
is mandatory in any surgical patient, including those with varicose veins. Most
individuals having operations for varicose veins requiring general or regional
anesthesia do not need heparin prophylaxis as the risk of thromboembolism
appears low. The use of physical compression, including heavier hose following
discharge (our local practice), serves to minimize wound hematoma and thrombus
formation, and hastens recovery. Scientific validation of these postulates,
however, awaits further study. 5068b
SOURCE: Campbell WB, Ridler BMF.Br J
Surg 1995; 82:1494-97
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REFERENCE
1. B–hler K, Baldt M, Schuller-Petrovic S, et al. Varicose vein stripping: A
prospective study of the thrombotic risk and the diagnostic significance of
preoperative color-coded duplex sonography. Thromb Haemost 1995; 73(4):597-600.
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