The efficacy of the new SCD response compression system in the prevention of venous stasis

OBJECTIVE: The current commercially available sequential intermittent pneumatic compression device used for the prevention of deep venous thrombosis has a constant cycle of 11 seconds' compression and 60 seconds' deflation. This deflation period ensures that the veins are filled before the subsequent cycle begins. It has been suggested that in some positions (eg, semirecumbent or sitting) and with different patients (eg, those with venous reflux), refilling of the veins may occur much earlier than 60 seconds, and thus a more frequent cycle may be more effective in expelling blood proximally. The aim of the study was to test the effectiveness of a new sequential compression system (the SCD Response Compression System), which has the ability to detect the change in the venous volume and to respond by initiating the subsequent cycle when the veins are substantially full. METHODS: In an open controlled trial at an academic vascular laboratory, the SCD Response Compression System was tested against the existing SCD Sequel Compression System in 12 healthy volunteers who were in supine, semirecumbent, and sitting positions. The refilling time sensed by the device was compared with that determined from recordings of femoral vein flow velocity by the use of duplex ultrasound scan. The total volume of blood expelled per hour during compression was compared with that produced by the existing SCD system in the same volunteers and positions. RESULTS: The refilling time determined automatically by the SCD Response Compression System varied from 24 to 60 seconds in the subjects tested, demonstrating individual patient variation. The refilling time (mean +/- SD) in the sitting position was 40.6 +/- 10. 0 seconds, which was significantly longer (P <.001) than that measured in the supine and semirecumbent positions, 33.8 +/- 4.1 and 35.6 +/- 4.9 seconds, respectively. There was a linear relationship between the duplex scan-derived refill time (mean of 6 readings per leg) and the SCD Response device-derived refill time (r = 0.85, P <. 001). The total volume of blood (mean +/- SD) expelled per hour by the existing SCD Sequel device in the supine, semirecumbent, and sitting positions was 2.23 +/- 0.90 L/h, 2.47 +/- 0.86 L/h, and 3.28 +/- 1.24 L/h, respectively. The SCD Response device increased the volume expelled to 3.92 +/- 1.60 L/h or a 76% increase (P =.001) in the supine position, to 3.93 +/- 1.55 L/h or a 59% increase (P =. 001) in the semirecumbent position, and to 3.97 +/- 1.42 L/h or a 21% increase (P =.026) in the sitting position. CONCLUSIONS: By achieving more appropriately timed compression cycles over time, the new SCD Response System is effective in preventing venous stasis by means of a new method that improves on the clinically documented effectiveness of the existing SCD system. Further studies testing its potential for improved efficacy in preventing deep venous thrombosis are justified.     

Effectiveness of leg compression in preventing venous stasis

To compare the ability of intermittent calf compression with that of sequential leg compression to prevent venous stasis, the clearance times of radiopaque dye, as determined by sequential phleborheograms performed on anesthetized patients, were compared. Calf compression was superior to no compression in clearing the dye from the calf alone, but did not aid clearance from the rest of the leg. Sequential leg compression was superior to intermittent calf compression in clearing dye from the calf and popliteal areas. Since intermittent leg compression has been as effective as small-dose heparin therapy in preventing postoperative deep venous thrombosis [7], the use of sequential leg compression may prove to be more effective and have less complications than heparin administration.     

Evidence-based compression: prevention of stasis and deep vein thrombosis

OBJECTIVE: To summarize the currently published scientific evidence for the venous flow effects of mechanical devices, particularly intermittent pneumatic compression, and the relation to prevention of deep vein thrombosis (DVT). SUMMARY BACKGROUND DATA: While intermittent pneumatic compression is an established method of DVT prophylaxis, the variety of systems that are available can use very different compression techniques and sequences. In order for appropriate choices to be made to provide the optimum protection for patients, the general performance of systems, and physiological effects of particular properties, must be analyzed objectively. METHODS: Medline was searched from 1970 to 2002, and all relevant papers were searched for further appropriate references. Papers were selected for inclusion when they addressed specifically the questions posed in this review. RESULTS: All the major types of intermittent compression systems are successful in emptying deep veins of the lower limb and preventing stasis in a variety of subject groups. Compression stockings appear to function more by preventing distension of veins. Rapid inflation, high pressures, and graded sequential intermittent compression systems will have particular augmentation profiles, but there is no evidence that such features improve the prophylactic ability of the system. CONCLUSIONS: The most important factors in selecting a mechanical prophylactic system, particularly during and after surgery, are patient compliance and the appropriateness of the site of compression. There is no evidence that the peak venous velocity produced by a system is a valid measure of medical performance.     

Intermittent pneumatic compression prevents venous stasis in the lower extremities in the lithotomy position

PURPOSE: To investigate the interactions of a new lithotomy positioning device (LPD) with two intermittent pneumatic compression (IPC) devices by measuring femoral venous flow velocity. METHODS: Subjects were divided into three groups: 1) supine position as a control, 2) lithotomy position using a conventional LPD, and 3) lithotomy position using a new LPD, Levitator(TM). These three groups were further divided in two according to the type of IPC device used: AV-impulse(TM) (rapid IPC) and SeQuel(TM) (standard IPC). Peak femoral venous flow velocity was measured by using an ultrasonic echo diagnostic device. Data were analyzed by one-way ANOVA with Fisher's test or by the unpaired two-tailed t test. RESULTS: Moving to the conventional lithotomy position from the supine position, venous flow velocity was decreased by 38% in both IPC device groups. Even when the new LPD was used to support the lithotomy position, the flow velocity was decreased by 24%, but the velocity was significantly higher than in the conventional lithotomy position. Both rapid and standard IPC devices increased flow velocity to 77% and 107% (first compression) and to 71% and 84% (fifth compression) of the control values during compression, respectively. In the lithotomy position group using the new LPD, similar increases in flow were seen with the use of IPC devices. CONCLUSION: Both rapid and standard IPC devices are useful for maintaining venous flow of the lower extremities in the lithotomy position.     

Why insurers should reimburse for compression stockings in patients with chronic venous stasis

BACKGROUND: Chronic venous stasis ulcers produce substantial morbidity rates and result in a significant expense to society. Fortunately, compression stockings (CS) have been found to reduce the rate of recurrence in patients with previous ulceration. Surprisingly, Medicare and other insurers do not reimburse the expense associated with CS or with patient education (Ed), which is essential to ensure compliance. METHODS: A Markov decision analysis model was used for analysis of the cost-effectiveness of a strategy of reimbursement for CS and Ed (prophylaxis) versus one that does not supply these resources in a 55-year-old patient with prior venous stasis ulceration. The mean time to ulcer recurrence (53 months with CS+Ed; 18.7 months without prophylaxis), the mean time for ulcer healing (4.6 months), the probabilities of hospitalization (12%) and amputation (0.4%) after the development of an ulcer, and quality-adjustment factors (0.80 during ulcer treatment) were derived from the literature. The cost of CS ($300/year) and Ed ($93 for initial evaluation; $58/year; $40/recurrence) and the medical cost of ulcer treatment (average cost, $1621/recurrence) were calculated from our hospital cost accounting system. RESULTS: A strategy of CS and Ed was cost saving, with 0.37 quality-adjusted life years and $5904 saved, compared with a strategy that does not provide these resources. The inclusion of loss of revenue related to absence from work in the analysis increased cost savings to $17,080 during the patient's lifetime. With sensitivity analysis, CS and Ed remained cost-effective (lifetime cost per quality-adjusted life year saved, <$60,000) if amputations and the cost of ulcer treatment were eliminated or if the cost of prophylaxis was increased to 600% of the base-case. The mean time to recurrence in patients with CS and Ed needed to be reduced from 53 months to 21.1 months before this strategy was no longer cost-effective. CONCLUSION: Prophylactic CS and Ed in patients with prior venous stasis ulceration are cost saving, even with the most conservative of assumptions. Insurers should routinely reimburse for these interventions.     

间歇性充气加压治疗在预防静脉血栓形成效果的Meta分析

目的：评价间歇性充气加压（IPC）治疗在预防静脉血栓形成的效果。 方法：检索中外文数据库所有关于IPC治疗来预防静脉血栓形成的随机对照试验（RCT）。按照纳入、排除标准纳入文献,并采用RevMan 5.2软件Meta分析。 结果：最终纳入63个RCT,共15 444例患者。Meta分析结果显示,与无干预组比较,IPC治疗组深静脉血栓（DVT）的发生率（OR=0.34,95% CI=0.26~0.45,P<0.00001）和肺栓塞（PE）的发生率（OR=0.45,95% CI=0.31~0.65,P<0.0001）明显减少;与压力循环袜（TEDS）治疗组比较,IPC组DVT的发生率（OR=0.55,95% CI=0.35~0.88,P=0.00001）明显减少;与抗凝药物治疗组比较,IPC组在预防DVT方面无优势（OR=1.05,95% CI=0.69~1.59,P=0.82）,但出血风险（OR=0.31,95% CI=0.19~0.50,P<0.00001）明显降低。 结论：在预防住院患者静脉血栓方面,IPC治疗具有明显的疗效,且无抗凝药物治疗所带来的出血风险。     

Consistent application of compression: An under-considered variable in the prevention of venous leg ulcers

Venous leg ulcers, the most common leg ulcer, occur in patients with chronic venous insufficiency due to venous hypertension. Evidence supports the conservative treatment with lower extremity compression, ideally between 30–40 mm Hg. Pressures in this range provide enough force to partially collapse lower extremity veins without restricting arterial flow in patients without peripheral arterial disease. There are many options for applying such compression, and those who apply these devices have varying levels of training and backgrounds. In this quality improvement project, a single observer utilised a reusable pressure monitor to compare pressures applied using different devices by individuals in wound clinics with diverse training from specialties of dermatology, podiatry, and general surgery. Average compression was higher in the dermatology wound clinic (n = 153) compared to the general surgery clinic (n = 53) (35.7 ± 13.3 and 27.2 ± 8.0 mm Hg, respectively, p < 0.0001), and wraps applied by clinic staff (n = 194) were nearly twice as likely as a self-applied wrap (n = 71) to have pressures greater than 40 mm Hg (relative risk: 2.2, 95% confidence interval: 1.136–4.423, p = 0.02). Pressures were also dependent upon the specific compression device used, with CircAid®s (35.5 mm Hg, SD: 12.0 mm Hg, n = 159) providing higher average pressures than Sigvaris Compreflex (29.5 mm Hg, SD: 7.7 mm Hg, n = 53, p = 0.009) and Sigvaris Coolflex (25.2 mm Hg, SD: 8.0 mm Hg, n = 32, p < 0.0001). These results indicate that the device-provided pressure may be dependent on both the compression device and the background and training of the applicator. We propose that standardisation in the training of compression application and increased use of a point-of-care pressure monitor may improve the consistency of applied compression, thus improving adherence to treatment and outcomes in patients with chronic venous insufficiency.     

Postoperative deep venous thrombosis prevention with intermittent sequential compression

The euglobulin lysis time (ELT) in antecubital vein and femoral vein was investigated in 35 patients before and after bilateral intermittent sequential leg compression for one hour. After compression, ELT in antecubital vein was shortened, and that in femoral vein was significantly shortened (p less than 0.05). beta-thromboglobulin, fibrinopeptide B beta 15-42 and alpha 2-plasmin inhibitor were also investigated, but no significant change was found after compression. The mean and peak blood velocity of the femoral vein before and during compression was measured using Doppler ultrasound in 20 patients. The mean blood velocity increased about 183% (p less than 0.001), and the peak blood velocity also increased 178% (p less than 0.001). ELT was measured pre- and post-operatively in 31 patients who had intermittent sequential compression during operation and succeeding two days and in 31 controls which had no compression. Both in antecubiltal vein and in femoral vein, ELT in the compression group was significantly shorter than that of control group in the first postoperative day. This study demonstrates that intermittent sequential compression of the legs increased fibrinolytic activity, and this effect may contribute to the prevention of deep venous thrombosis.     

Rapid-inflation intermittent pneumatic compression for prevention of deep venous thrombosis

BACKGROUND: Current treatment regimens that are designed to prevent deep venous thrombosis in patients undergoing orthopaedic procedures rely predominantly on drug prophylaxis alone. The purpose of this randomized clinical study was to evaluate the effectiveness of a mechanical adjunct to chemoprophylaxis that involves intermittent compression of the legs. METHODS: During a twenty-two month period, 1803 patients undergoing a variety of orthopaedic procedures were prospectively randomized to receive either chemoprophylaxis alone or a combination of chemoprophylaxis and mechanical prophylaxis. Nine hundred and two patients were managed with low-molecular-weight heparin alone, and 901 were managed with low-molecular-weight heparin and intermittent pneumatic compression of the calves for varying time periods. Twenty-four percent of the patients underwent total hip or knee joint replacement. Screening for deep venous thrombosis was performed on the day of discharge with duplex-color-coded ultrasound. RESULTS: In the chemoprophylaxis-only group, fifteen patients (1.7%) were diagnosed with a deep venous thrombosis; three thromboses were symptomatic. In the chemoprophylaxis plus intermittent pneumatic compression group, four patients (0.4%) were diagnosed with deep venous thrombosis; one thrombosis was symptomatic. The difference between the groups with regard to the prevalence of deep venous thrombosis was significant (p = 0.007). In the chemoprophylaxis plus intermittent pneumatic compression group, no deep venous thromboses were found in patients who received more than six hours of intermittent pneumatic compression daily. CONCLUSIONS: Venous thrombosis prophylaxis with low-molecular-weight heparin augmented with a device that delivers rapid-inflation intermittent pneumatic compression to the calves was found to be significantly more effective for preventing deep venous thrombosis when compared with a treatment regimen that involved low-molecular-weight heparin alone.     

中筒弹力袜预防下肢深静脉血栓效果的Meta分析

目的：综合评价中筒弹力袜在预防下肢深静脉血栓形成（DVT）中应用价值。 方法：检索多个中外文数据库上关于医用弹力袜预防下肢DVT的随机对照试验（RCT）。按照纳入排除标准筛选和提取文献,并采用RevMan 5.2软件进行统计学分析。 结果：最终纳入12个随机对照试验,共6 049例患者。Meta分析结果显示,在高危长途飞行乘客中,中筒弹力袜组较无袜对照组发生下肢DVT的风险明显降低（OR=0.08,95% CI=0.03~0.22,P<0.00001）;在住院患者中,中筒弹力袜组与长筒弹力袜在预防下肢DVT方面差异无统计学意义（OR=1.47,95% CI=0.69~3.13,P=0.32）;将住院患者及高危长途飞行的乘客合并分析,中筒弹力袜组发生下肢DVT的风险较无袜及长筒弹力袜组明显降低（OR=0.32,95% CI=0.11~0.92,P=0.03）。 结论：中筒弹力袜可减少高危长途飞行乘客与住院患者发生下肢DVT的风险,且效果优于长筒弹力袜,但仍需大样本、高质量的临床随机对照试验来验证。     

Management of venous stasis ulcer: long-term follow-up

In this study 112 patients (122 lower limbs) who had chronic venous stasis ulceration refractory to conservative management were treated surgically. Subfascial ligation was performed on 118 limbs and the long saphenous vein was removed in 4. Complications consisted of postoperative thrombophlebitis (2%), wound infection (2%) and wound infection with ulcer necrosis (1.5%). These all responded to conservative management. Follow-up (mean 7.9 years, median 11 years) showed a good or excellent result in 82% of cases, with healing of the ulcer and no ulcer recurrence despite significant noncompliance with support stockings. This paper is a long-term follow-up study of a surgical procedure for chronic venous stasis ulcers. The authors believe that the 82% good and excellent results may indicate that surgical intervention for refractory venous ulcers is a worthwhile procedure, providing potentially satisfactory long-term results.     

Intermittent pneumatic sequential compression (ISC) of the lower extremities prevents venous stasis during laparoscopic cholecystectomy

Background: Fifty patients were included in a prospective randomized trial to evaluate the efficacy of intermittent sequential compression (ISC) of the lower extremities in preventing venous stasis during laparoscopic cholecystectomy. Methods: We treated 25 patients with (+ISC) and 25 without (–ISC) intermittent sequential compression. Peak flow velocity (PFV) and cross-sectional area (CSA) of the right femoral vein were measured by Doppler ultrasound before, during, and after capnopneumoperitoneum with 14 mm Hg. Results: PFV was 26.4 (8.4) cm/s and CSA was 1.03 (0.23) cm² before pneumoperitoneum was induced. During abdominal insufflation, PFV decreased to 61% of the baseline value in the (–ISC) group but remained unchanged in the (+ISC) group (t = 5.17, df = 42.8, p < 0.01). CSA was 1.06 (0.22) cm² before insufflation. It increased to 118% of the baseline in the (–ISC) group and to 108% in the (+ISC) group (t =–1.55, df = 47.1, p= 0.13). PFV and CSA returned to baseline values within 5 min after abdominal desufflation. Conclusions: ISC effectively neutralizes venous stasis during laparoscopic surgery and may decrease the risk of postoperative thromboembolic complication. Therefore, it is recommended for all prolonged laparoscopic procedures. Received: 10 April 1996/Accepted: 24 April 1997     

The efficacy of a new portable sequential compression device (SCD Express) in preventing venous stasis

OBJECTIVE: It has been previously shown that the SCD Response Compression System, by sensing the postcompression refill time of the lower limbs, delivers more compression cycles over time, resulting in as much as a 76% increase in the total volume of blood expelled per hour. Extended indications for pneumatic compression have necessitated the introduction of portable devices. The aim of our study was to test the hemodynamic effectiveness of a new portable sequential compression system (the SCD Express), which has the ability to detect the individual refill time of the two lower limbs separately. METHODS: This was an open, controlled trial with 30 normal volunteers. The new SCD Express was compared with the SCD Response Compression System in the supine and semirecumbent positions. The refilling time sensed by the device was compared with that determined from velocity recordings of the superficial femoral vein using duplex ultrasonography. Baseline and augmented flow velocity and volume flow, including the total volume of blood expelled per hour during compression with the SCD Express, were compared with those produced by the SCD Response compression system in the same volunteers and positions. RESULTS: Both devices significantly increased venous flow velocity as much as 2.26 times baseline in supine position and 2.67 times baseline in semirecumbent position (all P < .001). There was a linear relationship between duplex ultrasonography-derived refill time and the SCD Express-derived refill time in both the supine (r = 0.39, P = .03) and semirecumbent (r = 0.71, P < .001) positions but not with the SCD Response. Refill time measured by the SCD Express device was significantly shorter and the cycle rate higher in comparison with the SCD Response in both positions. The single-cycle flow velocity and volume flow parameters generated by the two devices were similar in both positions. However, median (interquartile range) total volume of blood expelled per hour was slightly higher with the SCD Express device in the supine position (7206 mL/h [range, 5042-8437] vs 6712 mL/h [4941-10,676]; P = .85) and semirecumbent position (4588 mL/h [range, 3721-6252] vs 4262 mL/h [3520-5831]; P = .22). Peak volume of blood expelled per hour by the SCD Express device in the semirecumbent position was significantly increased by 10% in comparison with the SCD Response (P = .03). CONCLUSIONS: Flow velocity and volume flow enhancement by the SCD Response and SCD Express were essentially similar. The latter, a portable device with optional battery power that detects the individual refill time of the lower limbs separately, is anticipated to be associated with improved overall compliance and therefore optimized thromboprophylaxis. Studies testing its potential for improved efficacy in preventing deep vein thrombosis are justified.     

The effectiveness of intermittent plantar venous compression in prevention of deep venous thrombosis after total hip arthroplasty

The purpose of this study was to investigate the effectiveness of intermittent pneumatic compression of the plantar venous plexus with the newly developed arteriovenous impulse system. Seventy-four patients about to undergo primary unilateral total hip arthroplasty for osteoarthrosis, all receiving a standard thrombosis prophylaxis regime of thigh-length anti-embolic stockings, 5,000 IU heparin delivered subcutaneously twice daily, and 400 mg hydroxychloroquine sulfate delivered twice daily, were entered in a prospective trial. The patients were allocated at random to also receive the arteriovenous impulse system on the foot of the operated side. On approximately postoperative day 12 bilateral ascending venography was performed. There were 44 patients in the nonpumped group and 30 patients in the pumped group. The incidence of deep venous thrombosis was 6.6% in the pumped group and 27.27% in the non-pumped group. The incidence of thrombosis was significantly lower in the pumped group (P<.025). The authors conclude that chemical prophylaxis plus the use of the mechanical, pneumatic, and arteriovenous impulse system reduces the incidence of thromboembolic complications further than chemical prophylaxis alone.     

Compression characteristics of graduated compression stockings used for prevention of venous thromboembolism

BACKGROUND: Graduated compression stockings (GCS) are widely used to prevent perioperative venous thromboembolism. However, actual compression pressures of GCS on patients' legs have rarely been reported. METHODS: Four different types of GCS were evaluated. Compression pressures of GCS were measured hydrostatically by using a small balloon filled with water at the ankle, the calf and the knee (proximal end) in 463 legs of surgical patients. We also compared the influence of body mass index (BMI) on compression pressures of each GCS. RESULTS: No GCS ideally exerted compression of each sites of the legs while maintaining adequate pressure gradient from the ankle to the knee. It revealed that adequate compression of the calf and pressure gradient between the ankle and the calf could hardly be achieved simultaneously. In some GCS, BMI did not influence compression pressure but in the others compression tended to increase in patients with increased BMI. CONCLUSIONS: As the compression characteristics of GCS are different among products, selection of GCS is important for its effective use. To select a proper GCS, measurement of actual compression pressure seems necessary.     

静脉瘀血对静脉动脉化皮瓣微循环的影响

目的研究静脉瘀血对静脉动脉化皮瓣微循环的影响。方法３０只新西兰大白兔随机分为Ａ、Ｂ、Ｃ３组，Ａ组为动脉皮瓣，Ｂ组为静脉动脉化皮瓣，Ｃ组为静脉瘀血的静脉动脉化皮瓣，每组各１０只。术后３０分钟，１，２，３，４，５小时分别应用显微电视系统通过耳窗对各组皮瓣微循环进行动态观察，７天后记录皮瓣成活情况。结果静脉瘀血的静脉动脉化皮瓣微循环血流缓慢，微血栓逐渐增多，皮瓣成活率低。结论静脉瘀血可破坏静脉动脉化皮瓣静脉系统的代偿机制，影响皮瓣血液灌流，从而导致皮瓣成活率下降     

Trends in the incidence of venous stasis syndrome and venous ulcer: a 25-year population-based study

BACKGROUND: The incidence rates of venous stasis syndrome and venous ulcer are uncertain, and trends in incidence are unknown. METHODS: We performed a retrospective review of the complete (inpatient and outpatient) medical records of a community population (Olmsted County, Minnesota) to estimate the incidence of venous stasis syndrome and venous ulcer during the 25-year period, 1966 to 1990, and to describe trends in incidence. RESULTS: A total of 1131 patients received a first lifetime diagnosis of venous stasis syndrome. A total of 263 patients received a first lifetime diagnosis of venous ulcer. The overall incidence of venous stasis syndrome and venous ulcer were 76.1 and 18.0 per 100,000 person-years, respectively. The incidence of both was higher in women than in men (83.7 vs 67.4 per 100,000 person-years for venous stasis syndrome; 20.4 vs 14.6 per 100,000 for venous ulcer) and increased with age for both sexes. There was no clear trend in the incidence of venous stasis syndrome over the 25-year period. Compared with 1966 to 1970, the incidence of venous ulcer decreased in 1971 to 1980, but was unchanged after 1981. Among 945 patients with venous stasis only, 60 subsequently had a venous ulcer. The average (+/- SD) time from venous stasis diagnosis to development of a venous ulcer was 5.0 (+/- 5.0) years. CONCLUSION: Venous stasis syndrome and venous ulcer are common, especially in the elderly population. The incidence of venous stasis syndrome has not changed since 1966, and venous ulcer incidence is unchanged since 1981. More accurate identification of patients at risk for venous stasis syndrome and venous ulcer and more effective prevention are needed.     

静脉瘀血对静脉动脉化皮瓣微循环的影响

目的研究静脉瘀血对静脉动脉化皮瓣微循环的影响。方法 30只新西兰大白兔随机分为 A、B、C 3组,A 组为动脉皮瓣,B 组为静脉动脉化皮瓣,C 组为静脉瘀血的静脉动脉化皮瓣,每组各10只。术后30分钟,1,2,3,4,5小时分别应用显微电视系统通过耳窗对各组皮瓣微循环进行动态观察,7天后记录皮瓣成活情况。结果静脉瘀血的静脉动脉化皮瓣微循环血流缓慢,微血栓逐渐增多,皮瓣成活率低。结论静脉瘀血可破坏静脉动脉化皮瓣静脉系统的代偿机制,影响皮瓣血液灌流,从而导致皮瓣成活率下降。     

Intermittent pneumatic calf compression for prevention of deep venous thrombosis in general abdominal surgery

A prospective randomized trial is described in 119 patients undergoing major abdominal general surgical procedures. Half of the patients were treated prophylactically with intermittent pneumatic calf compression, begun after the induction of anesthesia and continued until the patient was walking; the other half acted as controls. Deep venous thrombosis was detected by iodine-125 fibrinogen scanning and confirmed by venography, and did not differ significantly in the control and treated groups. One fatal pulmonary embolism occurred in each group. The presence of malignancy of the gastrointestinal tract did not influence the results. The findings suggest that pneumatic compression delayed the development of deep venous thrombosis postoperatively and that perhaps it should be continued until discharge from hospital.