Br. J. Surg. Vol. 64 (1977) 371-373
The efficacy of graduated compression stockings in the prevention of deep vein thrombosis J. H. S C U R R , S. Z. I B R A H I M , R. G. F A B E R A N D L. P. LE Q U E S N E * SUMMARY
The incidence of deep venous thrombosis (DVT) was studied by the 1261-fibrinogen technique in 70 patients who had had major abdominal operations and who were wearing graduated static compression stockings on one leg, the patient’s other leg being used as a control. In the whole group 7 patients developed bilateral D VT, 19 patients developed unilateral D VT in the control leg and only one patient developed unilateral DVT in the stockinged leg. The diflerence between stockinged and control legs was highly significant (P= 0.0003). In the 19 patients with malignant disease the incidence of DVT in the stockinged leg remained signgcantly less ( P = 0.037). It is concluded that graduated static compression stockings do reduce the incidence of postoperative deep venous thrombosis. INrecent years, on the basis of studies using the lZ6Ifibrinogen technique for its detection, a number of measures have been shown to reduce the incidence of deep venous thrombosis (DVT). These measures can be divided into two groups: those that influence the capacity of the blood to clot and those that are designed to prevent stasis of the venous return from the lower limb; amongst the latter are the use of intermittent calf stimulation (Browse and Negus, 1970; Rosenberg et al., 1975) and intermittent calf compression (Hills et al., 1972; Roberts and Cotton, 1974). Although there is evidence that elastic stockings of various sorts increase the velocity of venous flow from the lower leg (Myerowitz and Nelson, 1964; Makin et al., 1969), there is conflicting evidence as to their value in the prevention of DVT. On the one hand, Wilkins and his colleagues (Wilkins et al., 1952; Wilkins and Stanton, 1953) showed that elastic stockings do reduce the incidence of pulmonary embolus, while Makin (1969) found a reduced incience of DVT, but, on the other hand, Rosengarten et al. (1970) and Browse et al. (1974) were unable to find any difference between the incidence of DVT in stockinged and control legs. These differences may be due to the methods used in diagnosis, for while Wilkins and his colleagues and Makin relied on clinical evidence of thrombo-embolic disease, Rosengarten et al. (1970) and Browse et al. (1974) used lZ5I-fibrinogen. More recently a graduated static compression stocking? (Fig. 1) has been developed. The specific properties of the stocking are that it has one-way stretch, is contoured to the limb, has a circumferential knit, is seamless and has a gusset at the top to prevent gartering. The stocking is manufactured in 9 sizes, classified in length as short, regular and long and in circumference as small, medium and large, and it is assessed that 95 per cent of the population can be fitted with a suitable size. On the basis of experimental studies (Sigel et al., 1975) pressure exerted by the stocking is graduated to 18 mmHg at
Fig. 1. The features of a TED stocking (right) compared to a Tubigrip stocking (left). Note that the TED stocking is shaped to the foot and calf, with a gusset at the top to prevent any gartering effect. See text for the other features of the TED stocking.
the ankle, 14 at the mid-calf, 8 at the popliteal region, 10 at the lower thigh and 8 at the upper thigh. It is this stocking that has been studied in this trial. Patients and methods Studies were carried out on 75 patients over the age of 40 years (mean 61 years, range 42-80 years) undergoing major operations within the abdominal cavity. All patients gave their informed consent to participating in this study. All patients wore the stocking on one leg only, the side being decided randomly by the toss of a coin. The stocking size was determined and the stocking applied the evening before operation and was left in place until the ninth postoperative day. Five patients were excluded from the analysis of results, 3 because
* Department of Surgical Studies, The Middlesex Hospital, London. Requests for reprints to: Professor L.P. Le Quesne. t TED stocking, Kendall Company, Hospital Products Division.
372
J. H. Scurr et al.
Table I: OPERATIONS PERFORMED Biliary Large bowel Oesophagogastroduodenal Prostate Ovarian Adrenal Hepatic Practalol peritonitis Massive incisional hernia Table 11: INCIDENCE OF DEEP VENOUS THROMBOSIS IN THE WHOLE GR OUP Unilateral Bilateral
31 18
13 2
2 1
1 1 1
Total
~
Control legs (70) Stockinged legs (70)
19 (27%)
1U%)
7 (10%) 7(10%)
26 (37%)
8 (11%)
Between 3 and 6 hours after operation 100 pCi ~f ’ ~~I - f i b r i n o g en was given intravenously and the legs were examined by the method of Negus et al. (1968) on the first, second, third, fifth and seventh postoperative days. If DVT was suspected or diagnosed, the examination was performed every day thereafter; DVT was diagnosed by the criteria set out by Pai and Negus (1971). Surgical diathermy, for haemostatic purposes, was used in all operations. Initially no record was kept of the position of the diathermy plates, which were sometimes strapped t o the control leg and sometimes placed under the buttock. However, since the former position might influence the venous return from the control limb, in the last 47 patients care was taken to ensure that the plate was always placed under the buttock. The statistical significance between the incidence of DVT in stockinged and control legs was tested by Fisher’s exact test (the median test). The difference in the day of detection of the thrombus was tested by the Wilcoxon test for unpaired data.
Overall difference between control and stockinged legs, P = 04003 (Fisher’s exact test).
Results The overall incidence of DVT in the patients studied was 38 per cent. The incidence of DVT in control Table 111: INCIDENCE OF DEEP VENOUS and stockinged legs in the whole group is shown in THROMBOSIS I N 19 PATIENTS WITH MALIGNANT Table ZZ; 7 patients developed bilateral DVT while DISEASE 20 patients developed unilateral DVT, 19 in the Unilateral Bilateral Total control leg and 1 in the stockinged leg. 7 (37%) 3 (16%) 10 (53%) Control Legs (19) Whether expressed as the overall difference in the Stockinged legs (19) 1 (0.5%) 3 (16%) 4 (21%) incidence of DVT in the control and stockinged leg Overall difference between control and stockinged legs, (P= 0.0003), or as the difference in patients developP = 0.037 (Fisher’s exact test). ing unilateral thrombosis (P= 0.000005), these results are highly significant. The incidence of DVT in 19 patients with malignant disease is shown in Table ZZZ; Table IV: INCIDENCE OF DEEP VENOUS 3 patients developed bilateral DVT and 8 unilateral THROMBOSIS IN 47 PATIENTS WITH DIATHERMY PLATE UNDER BUTTOCK DVT, 7 in the control leg and 1 in the stockinged leg. Again, both the overall difference in the incidence of Unilateral Bilateral Total DVT (P= 0.037) and the difference in unilateral Control legs (47) 13 (28%) 4 (9%) 17 (36%) thrombosis (P = 0.02) were significant. Table ZV Stockinged legs (47) 1 (2%) 4 (9%) 5 (11%) shows the incidence of DVT in the 47 patients in Overall difference between control and stockinged legs, whom the diathermy plate was known to be under P = O W 0 6 (Fisher’s exact test). the buttock, and definitely not strapped to the control leg. It is seen that the distribution of DVT is similar to that in the whole group (Table ZZ) and the overall difference (P = 0.006) and the difference in unilateral O C o n t r o l leg thrombosis (P = 0.0004) remain highly significant. Test leg The majority of the cases of thrombus in the control leg were detected in the first 48 hours after operation, but this was not true for the stockinged leg (Fig. 2). Of the 7 patients with bilateral DVT, in 5 patients the thrombus occurred first in the control leg, in 1 it occurred first in the stockinged leg and in the remaining patient both were detected on the same day. However, in neither those patients with unilateral DVT nor those with bilateral thrombosis is the Days after o p er atio n difference in the time of detection of the thrombus statistically significant, possibly because of the smallFig. 2. Histogram showing the day on which DVT was first detected in the control and stockinged legs. This difference is ness of the sample. not significant (P = 0.09).
they died within 72 hours of operation (there being no evidence that any had pulmonary embolus but 2 of these patients had DVT confined to the calf in the control leg), 1 because he removed the stocking and 1 because of technical problems with the scintillation counter. Of the 70 patients remaining in the study, 38 wore the stocking on the right leg and 32 on the left leg. The operations performed on these 70 patients are shown in Table I. All patients were given potassium iodide 120 mg daily by mouth for 1-3 days preoperatively t o block thyroid uptake and were maintained on this dose daily for 3 weeks. If they were unable to take tablets or time had not been available for the preoperative dose 100 mg was given intravenously.
Discussion The results of this trial have shown clearly that the incidence of DVT judged by the 1251-fibrinogen test is significantly less in the legs of patients wearing a TED stocking compared to the patients’ other control legs. These results are in agreement with those of Holford (1976). He studied two groups of patients, one group wearing TED stockings on both legs and the other group acting as controls, and he found that the incidence of DVT in the stockinged group was half that in the control group. However, both the results reported here and Holford’s results are at complete variance with those of
Graduated compression stockings
373
Rosengarten et al. (1970) and Browse et al. (1974) is conceivable that the increased volume results in who failed to show that the wearing of elastic stock- further pooling and predisposes to DVT. This quesings gave any protection against DVT. It is noted, tion can only be resolved by further studies comparing however, that these latter authors were studying the the incidence of deep venous thrombosis in patients effects of Tubigrip, a two-way stretch cylinder which wearing stockings on both legs and control patients. is not contoured to the limb and has no gusset, so that it may produce gartering. Further, Browse et al. Acknowledgements were using one size of stocking (4RT 6.75 cm; Seton Our thanks are due to the Kendall Company, Hospital Products Ltd), regardless of the size of patients’ legs. Products Division, who supplied the stockings and provided It is claimed (Makin et al., 1969) that Tubigrip financial support for this study. increases the rate of venous return, but in fact Makin’s results were extremely variable; of his 13 patients only References 7 showed a marked increase in the velocity of the BROWSE N. L., JACKSON B. T., MAYO M. E. et al. (1974) The value of mechanical methods of preventing postoperative calf femoral venous blood while the others showed invein thrombosis. Er. J. Surg. 61, 219-223. significant changes between the control and the Tubi- BROWSE N. L. and NEGUS D. (1970) Prevention of postoperative gripped leg. The TED stocking (Fig. 1) was developed leg vein thrombosis by electrical muscle stimulation. An following the experimental work of Sigel et al. (1975), evaluation with 12sI-labelledfibrinogen. Br. Med. J. 3, who studied the effect on the rate of femoral venous 615418. flow of 5 compression cuffs placed around the ankle, HILLS N. H., PFLUG J. J., JEYASINGH K. et al. (1972) Prevention of deep vein thrombosis by intermittent pneumatic commid-calf, popliteal region, lower thigh and upper pression of the calf. Er. Med. J. 1, 131-135. thigh. By altering the pressures in the cuffs they dis- HOLFORD c. P. (1976) The effect of graduated static compression covered that the maximal, consistent increase in the on isotopically diagnosed deep vein thrombosis of the leg. velocity of the femoral venous flow (138 per cent) Br. J. Surg. 63, 157. was achieved by pressures of 18,14,8,10 and 8 mmHg LEWIS c. E., ANTOINE J., TALBOT w. A. et al. (1977) Elastic from the ankle to the upper thigh. By increasing the compression in the prevention of venous stasis: a reconsideration Am. J. Surg. (In the press.) pressures, flow velocity was further increased in some patients but in others it was slowed. These results MAKIN G. s. (1969) A clinical trial of ‘Tubigrip’ to prevent deep venous thrombosis. Br. J. Surg. 56, 373-375. were in agreement with those of Myerowitz and NelG. s., MAYES P. B. and HOLROYD A. M. (1969) Studies on son (1964), who found that a uniform pressure of MAKIN the effect of ‘Tubigrip’ on flow in the deep veins of the 10mmHg resulted in an increase in flow velocity in calf. Er. J. Surg. 56, 369-372. 80 per cent of their patients, but in 12 per cent there MYEROWITZ B. R. and CROOK A. (1960) Elastic-stocking comwas actual slowing while in 8 per cent there was no pression and venous blood-flow. Effect in the lower limb. effect. Lancet 2, 122-124. A recent study (Lewis et al., 1976) has been carried MYEROWITZ B. R. and NELSON R. (1964) Measurement of the velocity of blood in lower limb veins with and without out on the effect of TED stockings on the time of compression. Surgery 56, 48 1486. clearance of radiographic contrast material from the D., PINTO D. J., LE QUESNE L. P. et al. (1968) lasI-labelled leg. This showed that while TED stockings caused no NEGUS fibrinogen in the diagnosis of deep vein thrombosis and decrease in the size of the deep veins of the legs, the its correlation with phlebography. Er. J. Surg. 55, 835-839. average clearance times of contrast material from PAI B. Y. and NEGUS D. (1971) Prevention of deep-vein thromcalf, popliteal region and thigh were halved in the bosis with subcutaneous heparin. Lancet 2, 1098-1099. stockinged legs as compared to the control legs. It ROBERTS v. c. and COTTON L. T. (1974) Prevention of postoperative deep vein thrombosis in patients with malignant would appear therefore that TED stockings increase disease. Br. Med. J. 1, 358-360. the linear velocity of venous blood flow and also reduce pooling in the soleal sinuses and behind vein ROSENBERG I. L., EVANS M. and POLLOCK A. v. (1975) Prophylaxis of postoperative leg vein thrombosis by low dose subcusps. cutaneous heparin or peroperative calf muscle stimulaIt was noted in this study that there was a rather tion : a controlled clinical trial. Br. Med. J. 1, 649-651. high incidence of DVT in the control leg. On the ROSENGARTEN D. s., LAIRD J., JEYASINGH K. et al. (1970) The basis of this study and others, there is general agreefailure of compression stockings (Tubigrip) to prevent ment that the overall incidence of calf vein thrombosis deep vein thrombosis after surgery. Br. J. Surg. 57, 296299. in patients over the age of 45 years undergoing a major abdominal operation is about 30 per cent; and, SABRI s., ROBERTS v. c. and COTTON L. T. (1971) Effects of externally applied pressure on the haemodynamics of the furthermore, that some 30 per cent of those patients limb. Br. Med. J. 3, 503-508. who develop DVT have bilateral thromboses. Thus, SIGELlower B., EDELSTEIN A. L., SAVITCH L. et al. (1975) Type of 20 per cent of legs, rather than patients, are at risk compression for reducing venous stasis. A study of lower and this would have been the incidence expected in extremities during inactive recumbency. Arch. Surg. 10, our control group, while the actual finding was 37 171-175. per cent. This was probably due to a small sample SPIRO M., ROBERTS v. c. and FUCHARDS J. B. (1970) Effect of externally applied pressure on femoral vein blood flow. error but it raises the possibility that the incidence of Br. Med. J. 1, 119-723. DVT in the control leg was increased by the stocking R. w., MIXTER G. jun., STANTON J. R. et al. (1952) on the other leg, a possible explanation for this being WILKINS Elastic stockings in the prevention of pulmonary embolism described in the work of Spiro et al. (1970) and of a preliminary report. N. Engl. J. Med. 246, 360-364. Sabri et a]. (1971). These authors have shown that WILKINS R. w. and STANTON I. R. (1953) Elastic stockings in the externally applied pressure on one leg increases the prevention of pulmonary embolism. N. Engl. J. Med. 248, quantity of blood flowing through the other, and it 1087-1090.
31
The efficacy of graduated compression stockings in the prevention of deep vein thrombosis J. H. S C U R R , S. Z. I B R A H I M , R. G. F A B E R A N D L. P. LE Q U E S N E * SUMMARY
The incidence of deep venous thrombosis (DVT) was studied by the 1261-fibrinogen technique in 70 patients who had had major abdominal operations and who were wearing graduated static compression stockings on one leg, the patient’s other leg being used as a control. In the whole group 7 patients developed bilateral D VT, 19 patients developed unilateral D VT in the control leg and only one patient developed unilateral DVT in the stockinged leg. The diflerence between stockinged and control legs was highly significant (P= 0.0003). In the 19 patients with malignant disease the incidence of DVT in the stockinged leg remained signgcantly less ( P = 0.037). It is concluded that graduated static compression stockings do reduce the incidence of postoperative deep venous thrombosis. INrecent years, on the basis of studies using the lZ6Ifibrinogen technique for its detection, a number of measures have been shown to reduce the incidence of deep venous thrombosis (DVT). These measures can be divided into two groups: those that influence the capacity of the blood to clot and those that are designed to prevent stasis of the venous return from the lower limb; amongst the latter are the use of intermittent calf stimulation (Browse and Negus, 1970; Rosenberg et al., 1975) and intermittent calf compression (Hills et al., 1972; Roberts and Cotton, 1974). Although there is evidence that elastic stockings of various sorts increase the velocity of venous flow from the lower leg (Myerowitz and Nelson, 1964; Makin et al., 1969), there is conflicting evidence as to their value in the prevention of DVT. On the one hand, Wilkins and his colleagues (Wilkins et al., 1952; Wilkins and Stanton, 1953) showed that elastic stockings do reduce the incidence of pulmonary embolus, while Makin (1969) found a reduced incience of DVT, but, on the other hand, Rosengarten et al. (1970) and Browse et al. (1974) were unable to find any difference between the incidence of DVT in stockinged and control legs. These differences may be due to the methods used in diagnosis, for while Wilkins and his colleagues and Makin relied on clinical evidence of thrombo-embolic disease, Rosengarten et al. (1970) and Browse et al. (1974) used lZ5I-fibrinogen. More recently a graduated static compression stocking? (Fig. 1) has been developed. The specific properties of the stocking are that it has one-way stretch, is contoured to the limb, has a circumferential knit, is seamless and has a gusset at the top to prevent gartering. The stocking is manufactured in 9 sizes, classified in length as short, regular and long and in circumference as small, medium and large, and it is assessed that 95 per cent of the population can be fitted with a suitable size. On the basis of experimental studies (Sigel et al., 1975) pressure exerted by the stocking is graduated to 18 mmHg at
Fig. 1. The features of a TED stocking (right) compared to a Tubigrip stocking (left). Note that the TED stocking is shaped to the foot and calf, with a gusset at the top to prevent any gartering effect. See text for the other features of the TED stocking.
the ankle, 14 at the mid-calf, 8 at the popliteal region, 10 at the lower thigh and 8 at the upper thigh. It is this stocking that has been studied in this trial. Patients and methods Studies were carried out on 75 patients over the age of 40 years (mean 61 years, range 42-80 years) undergoing major operations within the abdominal cavity. All patients gave their informed consent to participating in this study. All patients wore the stocking on one leg only, the side being decided randomly by the toss of a coin. The stocking size was determined and the stocking applied the evening before operation and was left in place until the ninth postoperative day. Five patients were excluded from the analysis of results, 3 because
* Department of Surgical Studies, The Middlesex Hospital, London. Requests for reprints to: Professor L.P. Le Quesne. t TED stocking, Kendall Company, Hospital Products Division.
372
J. H. Scurr et al.
Table I: OPERATIONS PERFORMED Biliary Large bowel Oesophagogastroduodenal Prostate Ovarian Adrenal Hepatic Practalol peritonitis Massive incisional hernia Table 11: INCIDENCE OF DEEP VENOUS THROMBOSIS IN THE WHOLE GR OUP Unilateral Bilateral
31 18
13 2
2 1
1 1 1
Total
~
Control legs (70) Stockinged legs (70)
19 (27%)
1U%)
7 (10%) 7(10%)
26 (37%)
8 (11%)
Between 3 and 6 hours after operation 100 pCi ~f ’ ~~I - f i b r i n o g en was given intravenously and the legs were examined by the method of Negus et al. (1968) on the first, second, third, fifth and seventh postoperative days. If DVT was suspected or diagnosed, the examination was performed every day thereafter; DVT was diagnosed by the criteria set out by Pai and Negus (1971). Surgical diathermy, for haemostatic purposes, was used in all operations. Initially no record was kept of the position of the diathermy plates, which were sometimes strapped t o the control leg and sometimes placed under the buttock. However, since the former position might influence the venous return from the control limb, in the last 47 patients care was taken to ensure that the plate was always placed under the buttock. The statistical significance between the incidence of DVT in stockinged and control legs was tested by Fisher’s exact test (the median test). The difference in the day of detection of the thrombus was tested by the Wilcoxon test for unpaired data.
Overall difference between control and stockinged legs, P = 04003 (Fisher’s exact test).
Results The overall incidence of DVT in the patients studied was 38 per cent. The incidence of DVT in control Table 111: INCIDENCE OF DEEP VENOUS and stockinged legs in the whole group is shown in THROMBOSIS I N 19 PATIENTS WITH MALIGNANT Table ZZ; 7 patients developed bilateral DVT while DISEASE 20 patients developed unilateral DVT, 19 in the Unilateral Bilateral Total control leg and 1 in the stockinged leg. 7 (37%) 3 (16%) 10 (53%) Control Legs (19) Whether expressed as the overall difference in the Stockinged legs (19) 1 (0.5%) 3 (16%) 4 (21%) incidence of DVT in the control and stockinged leg Overall difference between control and stockinged legs, (P= 0.0003), or as the difference in patients developP = 0.037 (Fisher’s exact test). ing unilateral thrombosis (P= 0.000005), these results are highly significant. The incidence of DVT in 19 patients with malignant disease is shown in Table ZZZ; Table IV: INCIDENCE OF DEEP VENOUS 3 patients developed bilateral DVT and 8 unilateral THROMBOSIS IN 47 PATIENTS WITH DIATHERMY PLATE UNDER BUTTOCK DVT, 7 in the control leg and 1 in the stockinged leg. Again, both the overall difference in the incidence of Unilateral Bilateral Total DVT (P= 0.037) and the difference in unilateral Control legs (47) 13 (28%) 4 (9%) 17 (36%) thrombosis (P = 0.02) were significant. Table ZV Stockinged legs (47) 1 (2%) 4 (9%) 5 (11%) shows the incidence of DVT in the 47 patients in Overall difference between control and stockinged legs, whom the diathermy plate was known to be under P = O W 0 6 (Fisher’s exact test). the buttock, and definitely not strapped to the control leg. It is seen that the distribution of DVT is similar to that in the whole group (Table ZZ) and the overall difference (P = 0.006) and the difference in unilateral O C o n t r o l leg thrombosis (P = 0.0004) remain highly significant. Test leg The majority of the cases of thrombus in the control leg were detected in the first 48 hours after operation, but this was not true for the stockinged leg (Fig. 2). Of the 7 patients with bilateral DVT, in 5 patients the thrombus occurred first in the control leg, in 1 it occurred first in the stockinged leg and in the remaining patient both were detected on the same day. However, in neither those patients with unilateral DVT nor those with bilateral thrombosis is the Days after o p er atio n difference in the time of detection of the thrombus statistically significant, possibly because of the smallFig. 2. Histogram showing the day on which DVT was first detected in the control and stockinged legs. This difference is ness of the sample. not significant (P = 0.09).
they died within 72 hours of operation (there being no evidence that any had pulmonary embolus but 2 of these patients had DVT confined to the calf in the control leg), 1 because he removed the stocking and 1 because of technical problems with the scintillation counter. Of the 70 patients remaining in the study, 38 wore the stocking on the right leg and 32 on the left leg. The operations performed on these 70 patients are shown in Table I. All patients were given potassium iodide 120 mg daily by mouth for 1-3 days preoperatively t o block thyroid uptake and were maintained on this dose daily for 3 weeks. If they were unable to take tablets or time had not been available for the preoperative dose 100 mg was given intravenously.
Discussion The results of this trial have shown clearly that the incidence of DVT judged by the 1251-fibrinogen test is significantly less in the legs of patients wearing a TED stocking compared to the patients’ other control legs. These results are in agreement with those of Holford (1976). He studied two groups of patients, one group wearing TED stockings on both legs and the other group acting as controls, and he found that the incidence of DVT in the stockinged group was half that in the control group. However, both the results reported here and Holford’s results are at complete variance with those of
Graduated compression stockings
373
Rosengarten et al. (1970) and Browse et al. (1974) is conceivable that the increased volume results in who failed to show that the wearing of elastic stock- further pooling and predisposes to DVT. This quesings gave any protection against DVT. It is noted, tion can only be resolved by further studies comparing however, that these latter authors were studying the the incidence of deep venous thrombosis in patients effects of Tubigrip, a two-way stretch cylinder which wearing stockings on both legs and control patients. is not contoured to the limb and has no gusset, so that it may produce gartering. Further, Browse et al. Acknowledgements were using one size of stocking (4RT 6.75 cm; Seton Our thanks are due to the Kendall Company, Hospital Products Ltd), regardless of the size of patients’ legs. Products Division, who supplied the stockings and provided It is claimed (Makin et al., 1969) that Tubigrip financial support for this study. increases the rate of venous return, but in fact Makin’s results were extremely variable; of his 13 patients only References 7 showed a marked increase in the velocity of the BROWSE N. L., JACKSON B. T., MAYO M. E. et al. (1974) The value of mechanical methods of preventing postoperative calf femoral venous blood while the others showed invein thrombosis. Er. J. Surg. 61, 219-223. significant changes between the control and the Tubi- BROWSE N. L. and NEGUS D. (1970) Prevention of postoperative gripped leg. The TED stocking (Fig. 1) was developed leg vein thrombosis by electrical muscle stimulation. An following the experimental work of Sigel et al. (1975), evaluation with 12sI-labelledfibrinogen. Br. Med. J. 3, who studied the effect on the rate of femoral venous 615418. flow of 5 compression cuffs placed around the ankle, HILLS N. H., PFLUG J. J., JEYASINGH K. et al. (1972) Prevention of deep vein thrombosis by intermittent pneumatic commid-calf, popliteal region, lower thigh and upper pression of the calf. Er. Med. J. 1, 131-135. thigh. By altering the pressures in the cuffs they dis- HOLFORD c. P. (1976) The effect of graduated static compression covered that the maximal, consistent increase in the on isotopically diagnosed deep vein thrombosis of the leg. velocity of the femoral venous flow (138 per cent) Br. J. Surg. 63, 157. was achieved by pressures of 18,14,8,10 and 8 mmHg LEWIS c. E., ANTOINE J., TALBOT w. A. et al. (1977) Elastic from the ankle to the upper thigh. By increasing the compression in the prevention of venous stasis: a reconsideration Am. J. Surg. (In the press.) pressures, flow velocity was further increased in some patients but in others it was slowed. These results MAKIN G. s. (1969) A clinical trial of ‘Tubigrip’ to prevent deep venous thrombosis. Br. J. Surg. 56, 373-375. were in agreement with those of Myerowitz and NelG. s., MAYES P. B. and HOLROYD A. M. (1969) Studies on son (1964), who found that a uniform pressure of MAKIN the effect of ‘Tubigrip’ on flow in the deep veins of the 10mmHg resulted in an increase in flow velocity in calf. Er. J. Surg. 56, 369-372. 80 per cent of their patients, but in 12 per cent there MYEROWITZ B. R. and CROOK A. (1960) Elastic-stocking comwas actual slowing while in 8 per cent there was no pression and venous blood-flow. Effect in the lower limb. effect. Lancet 2, 122-124. A recent study (Lewis et al., 1976) has been carried MYEROWITZ B. R. and NELSON R. (1964) Measurement of the velocity of blood in lower limb veins with and without out on the effect of TED stockings on the time of compression. Surgery 56, 48 1486. clearance of radiographic contrast material from the D., PINTO D. J., LE QUESNE L. P. et al. (1968) lasI-labelled leg. This showed that while TED stockings caused no NEGUS fibrinogen in the diagnosis of deep vein thrombosis and decrease in the size of the deep veins of the legs, the its correlation with phlebography. Er. J. Surg. 55, 835-839. average clearance times of contrast material from PAI B. Y. and NEGUS D. (1971) Prevention of deep-vein thromcalf, popliteal region and thigh were halved in the bosis with subcutaneous heparin. Lancet 2, 1098-1099. stockinged legs as compared to the control legs. It ROBERTS v. c. and COTTON L. T. (1974) Prevention of postoperative deep vein thrombosis in patients with malignant would appear therefore that TED stockings increase disease. Br. Med. J. 1, 358-360. the linear velocity of venous blood flow and also reduce pooling in the soleal sinuses and behind vein ROSENBERG I. L., EVANS M. and POLLOCK A. v. (1975) Prophylaxis of postoperative leg vein thrombosis by low dose subcusps. cutaneous heparin or peroperative calf muscle stimulaIt was noted in this study that there was a rather tion : a controlled clinical trial. Br. Med. J. 1, 649-651. high incidence of DVT in the control leg. On the ROSENGARTEN D. s., LAIRD J., JEYASINGH K. et al. (1970) The basis of this study and others, there is general agreefailure of compression stockings (Tubigrip) to prevent ment that the overall incidence of calf vein thrombosis deep vein thrombosis after surgery. Br. J. Surg. 57, 296299. in patients over the age of 45 years undergoing a major abdominal operation is about 30 per cent; and, SABRI s., ROBERTS v. c. and COTTON L. T. (1971) Effects of externally applied pressure on the haemodynamics of the furthermore, that some 30 per cent of those patients limb. Br. Med. J. 3, 503-508. who develop DVT have bilateral thromboses. Thus, SIGELlower B., EDELSTEIN A. L., SAVITCH L. et al. (1975) Type of 20 per cent of legs, rather than patients, are at risk compression for reducing venous stasis. A study of lower and this would have been the incidence expected in extremities during inactive recumbency. Arch. Surg. 10, our control group, while the actual finding was 37 171-175. per cent. This was probably due to a small sample SPIRO M., ROBERTS v. c. and FUCHARDS J. B. (1970) Effect of externally applied pressure on femoral vein blood flow. error but it raises the possibility that the incidence of Br. Med. J. 1, 119-723. DVT in the control leg was increased by the stocking R. w., MIXTER G. jun., STANTON J. R. et al. (1952) on the other leg, a possible explanation for this being WILKINS Elastic stockings in the prevention of pulmonary embolism described in the work of Spiro et al. (1970) and of a preliminary report. N. Engl. J. Med. 246, 360-364. Sabri et a]. (1971). These authors have shown that WILKINS R. w. and STANTON I. R. (1953) Elastic stockings in the externally applied pressure on one leg increases the prevention of pulmonary embolism. N. Engl. J. Med. 248, quantity of blood flowing through the other, and it 1087-1090.
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