Analysis of the cost-efficiency of the vascular impulse technology (VIT) in the perioperative management of complex ankle fractures: results of a prospective randomised controlled trial

INTRODUCTION

Posttraumatic swelling causes a delay in surgery, a prolonged hospital stay and a higher risk of complications. Thus, soft tissue conditioning following complex ankle fractures is of central importance in their perioperative management. Since the clinical benefit of VIT usage on the clinical course has been shown, it should now be investigated whether it is also cost-efficient in doing so.

MATERIALS AND METHODS

Included are published clinical results of the prospective, randomised, controlled, monocentric VIT study that have proven the therapeutic benefit in complex ankle fractures. Participants were allocated in a 1:1 ratio into the intervention group (VIT) and the control group (elevation). In this study, the required economic parameters of these clinical cases were collected on the data of the financial accounting and an estimation of annual cases had been performed to extrapolate the cost-efficiency of this therapy. The primary endpoint was the mean savings (in €).

RESULTS

Thirty-nine cases were studied in the period from 2016 to 2018. There was no difference in the generated revenue. However, due to lower incurred costs in the intervention group, there were potential savings of about €2000 (p_ITT = 0.073) to 3000 (p_AT = 0.008) per patient compared to the control group with therapy costs decreasing as the number of patients treated increases from €1400 in one case to below €200 per patient in 10 cases. There were 20% more revision surgeries in the control group or 50 min more OR time, respectively, and an increased attendance by staff and medical personnel of more than 7 h.

CONCLUSIONS

VIT therapy has been shown to be a beneficial therapeutic modality, but it is so not only in regard to soft-tissue conditioning but also cost efficiency.

Vascular impulse technology versus elevation for reducing the swelling of upper and lower extremity joint fractures

Soft-tissue conditioning due to posttraumatic oedema after complicated joint fractures is a central therapeutic aspect both pre- and postoperatively. On average, 6-10 days pass until the patient is suitable for surgery. This study compares the decongestant effect of vascular impulse technology (VIT) with that of conventional elevation. In this monocentric RCT, 68 patients with joint fractures of the upper (n = 36) and lower (n = 32) extremity were included and randomized after consent in a 1:1 ratio. Variables were evaluated for all fractures together and additionally subdivided into upper or lower extremity for better clinical comparability. Primary endpoint was the time in days from hospital admission to operability. Secondary endpoints were total length of stay, oedema reduction, pain intensity, complications, and revisions. The time from admission until operability was reduced by 1.4 (95% CI - 0.4; 3.1) days in the mITT analysis (p = 0.120) and was statistically significant with 1.7 (95% CI 0.1; 3.3) days in the as-treated sensitivity analysis (p_AT = 0.038). Significantly less pain and a faster oedema reduction were found in the intervention group. Due to rare occurrences, nothing can be concluded regarding complications and revisions. Administration of VIT therapy did not lead to a significant reduction in time until operability in the whole population but was superior to elevation for soft-tissue conditioning and pain reduction. However, there was a significant reduction by 2.5 days (95% CI 0.7; 4.3) in the subgroup of lower extremity fractures. VIT therapy therefore seems to be a helpful tool in the treatment of posttraumatic oedema after complex joint fractures of the lower and upper extremity, especially in tibial head and lower leg fractures.

Vascular impulse technology versus elevation for the reduction of swelling of lower extremity joint fractures: results of a prospective randomized controlled study

AIMS

Complex joint fractures of the lower extremity are often accompanied by soft-tissue swelling and are associated with prolonged hospitalization and soft-tissue complications. The aim of the study was to evaluate the effect of vascular impulse technology (VIT) on soft-tissue conditioning in comparison with conventional elevation.

METHODS

A total of 100 patients were included in this prospective, randomized, controlled monocentre study allocated to the three subgroups of dislocated ankle fracture (n = 40), pilon fracture (n = 20), and intra-articular calcaneal fracture (n = 40). Patients were randomized to the two study groups in a 1:1 ratio. The effectiveness of VIT (intervention) compared with elevation (control) was analyzed separately for the whole study population and for the three subgroups. The primary endpoint was the time from admission until operability (in days).

RESULTS

The mean length of time until operability was 8.2 days (SD 3.0) in the intervention group and 10.2 days (SD 3.7) in the control group across all three fractures groups combined (p = 0.004). An analysis of the subgroups revealed that a significant reduction in the time to operability was achieved in two of the three: with 8.6 days (SD 2.2) versus 10.6 days (SD 3.6) in ankle fractures (p = 0.043), 9.8 days (SD 4.1) versus 12.5 days (SD 5.1) in pilon fractures (p = 0.205), and 7.0 days (SD 2.6) versus 8.4 days (SD 1.5) in calcaneal fractures (p = 0.043). A lower length of stay (p = 0.007), a reduction in pain (p_preop = 0.05; p_discharge < 0.001) and need for narcotics (p_preop = 0.064; p_postop = 0.072), an increased reduction in swelling (p < 0.001), and a lower revision rate (p = 0.044) could also be seen, and a trend towards fewer complications (p = 0.216) became apparent.

CONCLUSION

Compared with elevation, VIT results in a significant reduction in the time to achieve operability in complex joint fractures of the lower limb. Cite this article: Bone Joint J 2021;103-B(4):746-754.

Physiological Impact and Clinical Relevance of Passive Exercise/Movement

Passive exercise/movement has a long history in both medicine and physiology. Early clinical applications of passive exercise/movement utilized pneumatic and direct limb compression to stimulate the vasculature and evoke changes in blood flow to avoid complications brought about by stasis and vascular disease. Over the last 50 years, passive exercise/movement has continued to progress and has provided physiologists with a reductionist approach to mechanistically examine the cardiorespiratory, hyperemic, and afferent responses to movement without the confounding influence of metabolism that accompanies active exercise. This review, in addition to providing an historical perspective, focuses on the recent advancements utilizing passive leg movement, and how the hyperemic response at the onset of this passive movement has evolved from a method to evaluate the central and peripheral regulation of blood flow during exercise to an innovative and promising tool to assess vascular function. As an assessment of vascular function, passive leg movement is relatively simple to perform and provides a nitric oxide-dependent evaluation of endothelial function across the lifespan that is sensitive to changes in activity/fitness and disease state (heart failure, peripheral artery disease, sepsis). The continual refinement and characterization of passive leg movement are aimed at improving our understanding of blood flow regulation and the development of a clinically ready approach to predict and monitor the progression of cardiovascular disease.

Non-Invasive Management of Peripheral Arterial Disease

BACKGROUND

Peripheral arterial disease (PAD) is common and symptoms can be debilitating and lethal. Risk management, exercise, radiological and surgical intervention are all valuable therapies, but morbidity and mortality rates from this disease are increasing. Circulatory enhancement can be achieved using simple medical electronic devices, with claims of minimal adverse side effects. The evidence for these is variable, prompting a review of the available literature.

METHODS

Embase and Medline were interrogated for full text articles in humans and written in English. Any external medical devices used in the management of peripheral arterial disease were included if they had objective outcome data.

RESULTS

Thirty-one papers met inclusion criteria, but protocols were heterogenous. The medical devices reported were intermittent pneumatic compression (IPC), electronic nerve (NMES) or muscle stimulators (EMS), and galvanic electrical dressings. In patients with intermittent claudication, IPC devices increase popliteal artery velocity (49-70 %) and flow (49-84 %). Gastrocnemius EMS increased superficial femoral artery flow by 140 %. Over 4.5-6 months IPC increased intermittent claudication distance (ICD) (97-150 %) and absolute walking distance (AWD) (84-112 %), with an associated increase in quality of life. NMES of the calf increased ICD and AWD by 82 % and 61-150 % at 4 weeks, and 26 % and 34 % at 8 weeks. In patients with critical limb ischaemia IPC reduced rest pain in 40-100 % and was associated with ulcer healing rates of 26 %. IPC had an early limb salvage rate of 58-83 % at 1-3 months, and 58-94 % at 1.5-3.5 years. No studies have reported the use of EMS or NMES in the management of CLI.

CONCLUSION

There is evidence to support the use of IPC in the management of claudication and CLI. There is a building body of literature to support the use of electrical stimulators in PAD, but this is low level to date. Devices may be of special benefit to those with limited exercise capacity, and in non-reconstructable critical limb ischaemia. Galvanic stimulation is not recommended.

Intermittent pneumatic compression: physiologic and clinical basis to improve management of venous leg ulcers

Venous leg ulcers (VLUs) are a significant health problem that afflicts 1% of the population at some point during their lifetime. Intermittent pneumatic compression (IPC) is widely used to prevent deep venous thrombosis. However, IPC seems to have application to a broader base of circulatory diseases. The intermittent nature of pulsatile external compression produces beneficial physiologic changes, which include hematologic, hemodynamic, and endothelial effects, which should promote healing of VLUs. Clinical studies of the management of VLUs show that IPC increases overall healing and accelerates the rate of healing, leading to current guideline recommendations for care of patients with VLUs. Proper prescription of IPC to improve the management of patients with VLUs requires further definition. It seems that application of IPC in combination with sustained graduated compression improves outcome in patients with the most advanced venous disease.

Nonoperative active management of critical limb ischemia: initial experience using a sequential compression biomechanical device for limb salvage

Critical limb ischemia (CLI) patients are at high risk of primary amputation. Using a sequential compression biomechanical device (SCBD) represents a nonoperative option in threatened limbs. We aimed to determine the outcome of using SCBD in amputation-bound nonreconstructable CLI patients regarding limb salvage and 90-day mortality. Thirty-five patients with 39 critically ischemic limbs (rest pain = 12, tissue loss = 27) presented over 24 months. Thirty patients had nonreconstructable arterial outflow vessels, and five were inoperable owing to severe comorbidity scores. All were Rutherford classification 4 or 5 with multilevel disease. All underwent a 12-week treatment protocol and received the best medical treatment. The mean follow-up was 10 months (SD +/- 6 months). There were four amputations, with an 18-month cumulative limb salvage rate of 88% (standard error [SE] +/- 7.62%). Ninety-day mortality was zero. Mean toe pressures increased from 38.2 to 67 mm Hg (SD +/- 33.7, 95% confidence interval [CI] 55-79). Popliteal artery flow velocity increased from 45 to 47.9 cm/s (95% CI 35.9-59.7). Cumulative survival at 12 months was 81.2% (SE +/- 11.1) for SCBD, compared with 69.2% in the control group (SE +/- 12.8%) (p = .4, hazards ratio = 0.58, 95% CI 0.15-2.32). The mean total cost of primary amputation per patient is euro29,815 ($44,000) in comparison with euro13,900 ($20,515) for SCBD patients. SCBD enhances limb salvage and reduces length of hospital stay, nonoperatively, in patients with nonreconstructable vessels.

Prospective study to determine the effect of intermittent pneumatic foot and calf compression on popliteal artery peak systolic blood flow

OBJECTIVE

This study investigated the effects of posture and also intermittent foot and calf compression on peak systolic flow of the popliteal artery in a normal population.

METHODS

This was a prospective study carried out in normal subjects at the Vascular Laboratory, Department of Surgery, Hospital Kuala Lumpur, from March 2006 to September 2006. The study compared the popliteal artery blood flow during change of posture from the horizontal (supine) to the sitting position and the effect of intermittent pneumatic compression (IPC) of the foot and calf on popliteal artery blood flow immediately and 10 minutes after cessation of compression.

RESULTS

A total of 15 subjects involving 30 limbs were examined in this study. On comparing flows between the horizontal and sitting position, there was a mean reduction in blood flow of 23% (p < 0.005). Immediately after compression of the foot and calf, there was an increase in blood flow of between 4% and 35% with a mean of 15% (p < 0.05). Peak systolic flows at 10 minutes postcompression were 536 +/- 95 mL/min, which was still significantly higher than precompression measurements.

CONCLUSION

There is a significant reduction in popliteal artery blood flow on changing from the supine to the sitting position. Popliteal artery blood flow is higher than baseline after 15 minutes of intermittent pneumatic foot and calf compression. The increase in popliteal artery blood flow is still present 10 minutes after cessation of IPC.

Intermittent pneumatic compression regulates expression of nitric oxide synthases in skeletal muscles

This study investigated the effects of intermittent pneumatic compression (IPC) on expression of nitric oxide synthase (NOS) isoforms in compressed (anterior tibialis, AT) and uncompressed (cremaster muscles, CM) skeletal muscles. Following IPC application of 0.5, 1, and 5h on both legs of rats, the endothelial NOS (eNOS) mRNA expression was significantly up-regulated to 1.2-, 1.8, and 2.7-fold from normal, respectively, in both AT and CM, and protein expression increased more than 1.5-fold of normal at each time point. Similarly, neuronal NOS expression was up-regulated, but to a lesser degree. In contrast, inducible NOS expression was significantly and time-dependently down-regulated in both muscles. After IPC cessation, eNOS levels returned to normal in both AT and CM. The results confirm our hypothesis that IPC-induced vasodilation is mediated by regulating expression of NOS isoforms, in particular eNOS, in both compressed and uncompressed skeletal muscles. The results also suggest the importance of precisely characterizing expression of each NOS isoform in tissue pathophysiology.

Duration and amplitude decay of acute arterial leg inflow enhancement with intermittent pneumatic leg compression: An insight into the implicated physiologic mechanisms

PURPOSE

By acutely enhancing the arterial leg inflow, intermittent pneumatic leg compression (IPC) improves the walking ability, arterial hemodynamics, and quality of life of claudicants. We quantified the duration of acute leg inflow enhancement with IPC of the foot (IPC(foot)), calf (IPC(calf)), or both (IPC(foot+calf)) and its amplitude decay in claudicants and controls in relation to the pulsatility index, an estimate of peripheral resistance. These findings are cross-correlated with the features of the three implicated physiologic mechanisms: (1) an increase in the arteriovenous pressure gradient, (2) suspension of peripheral sympathetic autoregulation, and (3) enhanced release of nitric oxide with flow and shear-stress increase.

METHODS

Twenty-six limbs of 24 claudicants with superficial femoral artery occlusion or stenoses (>75%) and 24 limbs of 20 healthy controls matched for age and sex, meeting stringent selection criteria, had their popliteal volume flow and pulsating index (peak-to-peak velocity/mean velocity) measured with duplex scanning at rest and upon delivery of IPC. Spectral waveforms were analyzed for 50 seconds after IPC delivery per 5-second segments. The three IPC modes were applied in a true crossover design. Data analysis was performed with the Page, Friedman, Wilcoxon, Mann-Whitney and chi2 tests.

RESULTS

The median duration of flow enhancement in claudicants exceeded 50 seconds with IPC(foot), IPC(calf), and IPC(foot+calf) but was shorter (P < .001) in the controls (32.5 to 40 seconds). Among the three IPC modes, the duration of flow enhancement differed (P < .05) only between IPC(foot) and IPC(foot+calf). After reaching its peak within 5 seconds of IPC, flow enhancement decayed at rates decreasing over time (trend, P < .05, Page test), which in both groups were highest at 5 to 20 seconds, moderate at 20 to 35 seconds, and lowest at 35 to 50 seconds (P < .05, Friedman test). Baseline and peak flow with all IPC modes was similar between the two groups. Pulsatility index attenuation in claudicating limbs lasted a median 32.5 seconds with IPC(foot), 37.5 seconds with IPC(calf), and 40 seconds with IPC(foot+calf); duration of pulsatility index attenuation was shorter in the control limbs with IPC(foot) (30 seconds), IPC(calf) (32.5 seconds), or IPC(foot+calf) (35 seconds), yet differences, as well as those among the 3 IPC modes, were not significant.

CONCLUSION

Leg inflow enhancement with IPC exceeds 50 seconds in claudicants and lasts 32.5 to 40 seconds in the controls. Peak flow occurs concurrently with maximal pulsatility index attenuation, within 5 seconds of IPC. Irrespective of group or IPC mode, the decay rate (%) of flow enhancement is highest within 5 to 20 seconds of IPC, moderate at 20 to 35 seconds, and lowest at 35 to 50 seconds. Since attenuation in peripheral resistance terminates with the mid time period (20 to 35 seconds) of flow decay, and nitric oxide has a half-life of <7 to 10 seconds, the study's data indicate that all implicated physiologic mechanisms (1, 2, and 3) are likely active immediately after IPC delivery (0 to 20 sec) and all but nitric oxide are effective in the mid time period (20 to 35 seconds). As the pulsatility index has returned to baseline, the late phase of flow enhancement (35 to 50 seconds) could be attributable to the declining arteriovenous pressure gradient alone.

Rapid foot and calf compression increases walking distance in patients with intermittent claudication: results of a randomized study

OBJECTIVE

The aim of our pilot study was to determine the usefulness of rapid, high-pressure, intermittent pneumatic calf and foot compression (IPCFC) in patients with stable intermittent claudication, with reference to the end points of improvement in initial claudication distance (ICD) (distance at which patient feels pain or discomfort in the legs), and improvement in absolute claudication distance (ACD) (distance at which patient stops walking because the pain or discomfort becomes severe).

METHODS

Thirty male patients presenting with stable, intermittent claudication (ACD between 50 and 150 meters on treadmill testing at 3.8 km/h, 10 degrees gradient) were recruited into this pilot study from a single center. Fifteen patients were randomized to treatment with IPCFC (applied for 1 hour twice daily in the sitting position) and were also advised to have daily exercise, and 15 patients served as controls, who were advised exercise alone. All patients received aspirin and had resting and postexercise ankle/brachial index (ABI) measured at enrollment along with ICD and ACD on treadmill testing (3.8 km/h, 10 degrees gradient). The mean age, baseline ICD, and ACD of the treatment and control groups were 70.4 +/- 7 years and 70.7 +/- 9 years, 55.8 +/- 15 meters and 68.4 +/- 17 meters, and 86.7 +/- 19 meters and 103.9 +/- 27 meters, respectively. Both groups were equally matched for risk factors, including smoking, type II diabetes mellitus, and hypercholesterolemia. IPCFC was applied. The study protocol included follow-up visits at 1, 2, 3, 4, 6, and 12 months with the ABI, ICD and ACD being measured at every visit.

RESULTS

The percent change from baseline for ICD and ACD for each patient visit and the mean +/- standard deviation (SD), standard error (SE), and median were calculated for the control and treatment groups. The percent change from baseline measurements (mean +/- SD) for ICD and ACD in the control group at 4, 6, and 12 months were 2.2 +/- 18 and 2.3 +/- 18, 2.9 +/- 17 and 5.2 +/- 20, and 3.6 +/- 18 and 5.8 +/- 20, respectively. In contrast, the changes in ICD and ACD at 4, 6, and 12 months in the treatment group were 137.1 +/- 128 (P < .01) and 84.3 +/- 82 (P < .01), 140.6 +/- 127 (P < .01) and 96.4 +/- 106 (P = .01), and 150.8 +/- 124 (P <0.01) and 101.2 +/- 104 (P <0.01), respectively. Although the ABI showed a slight increase in the treatment group, these differences were not statistically significant.

CONCLUSIONS

The results of this pilot study show that IPCFC improves walking distance in patients with stable intermittent claudication. A significant increase in ICD and ACD was seen at 4 and 6 months of treatment, respectively, and the improvement was sustained at 1 year. The combination of IPCFC with other treatment such as risk-factor modification and daily exercise may prove useful in patients with peripheral arterial occlusive disease. It may be a useful first line of therapy in patients with disabling claudication who are unfit for major reconstructive surgery. Improved walking on long-term follow-up and experience from different centers may establish a role for this treatment modality in the future.

Effect of intermittent pneumatic compression of foot and calf on walking distance, hemodynamics, and quality of life in patients with arterial claudication: a prospective randomized controlled study with 1-year follow-up

SUMMARY BACKGROUND DATA

Perioperative mortality, graft failure, and angioplasty limitations militate against active intervention for claudication. With the exception of exercise programs, conservative treatments yield modest results. Intermittent pneumatic compression [IPC] of the foot used daily for 3 months enhances the walking ability and pressure indices of claudicants. Although IPC applied to the foot and calf together [IPCfoot+calf] is hemodynamically superior to IPC of the foot, its clinical effects in claudicants remain undetermined.

OBJECTIVE

This prospective randomized controlled study evaluates the effects of IPCfoot+calf on the walking ability, peripheral hemodynamics, and quality of life [QOL] in patients with arterial claudication.

METHODS

Forty-one stable claudicants, meeting stringent inclusion and exclusion criteria, were randomized to receive either IPCfoot+calf and aspirin[75 mg] (Group 1; n = 20), or aspirin[75 mg] alone (Group 2; n = 21), with stratification for diabetes and smoking. Groups matched for age, sex, initial [ICD] and absolute [ACD] claudication distances, pressure indices [ABI], popliteal artery flow, and QOL with the short-form 36 Health Survey Questionnaire (SF-36). IPCfoot+calf (120 mm Hg, inflation 4 seconds x 3 impulses per minute, calf inflate delay 1 second) was used for 5 months, > or =2.5 hours daily. Both groups were advised to exercise unsupervised. Evaluation of patients, after randomization, included the ICD and ACD, ABI, popliteal artery flow with duplex and QOL* at baseline*, 1/12, 2/12, 3/12, 4/12, 5/12* and 17/12. Logbooks allowed compliance control. Wilcoxon and Mann-Whitney corrected[Bonferroni] tests were used.

RESULTS

At 5/12 median ICD, ACD, resting and postexercise ABI had increased by 197%, 212%, 17%, and 64%, respectively, in Group 1 (P < 0.001), but had changed little (P > 0.1) in Group 2; Group 1 had better ICD, ACD, and resting and postexercise ABI (P < 0.01) than Group 2. Inter- and intragroup popliteal flow differences at 5/12 were small (P > 0.1). QOL had improved significantly in Group 1 but not in Group 2; QOL in the former was better (P < 0.01) than in Group 2. QOL in Group 1 was better (P < 0.01) than in Group 2 at 5/12. IPC was complication free. IPC compliance (> or =2.5 hours/d) was >82% at 1 month and >85% at 3 and 5 months. ABI and walking benefits in Group 1 were maintained a year after cessation of IPC treatment.

CONCLUSIONS

IPCfoot+calf emerged as an effective, high-compliance, complication-free method for improving the walking ability and pressure indices in stable claudication, with a durable outcome. These changes were associated with a significant improvement in all aspects of QOL evaluated with the SF-36. Despite some limited benefit noted in some individuals, unsupervised exercise had a nonsignificant impact overall.

Intermittent venous compression, and the duration of hyperaemia in the common femoral artery

External compression of limbs to below-diastolic pressure (venous compression) has been shown to produce a short-lived hyperaemia in supply arteries. Intermittent pneumatic compression is currently under investigation therefore as a treatment for peripheral arterial disease. The optimal timing of the compression will depend on the duration of hyperaemia produced by a particular duration of compression, and the purpose of this work was to test that link. Nineteen healthy volunteers underwent intermittent compression of one leg with two compression cycles - one compressing for 10 s each time, the other for 1 min. Blood flow velocities in the common femoral artery was shown to increase on release of the compression by 38% (inter-quartile range 27-56%) for the sequence with short duration compression, and by 57% (inter-quartile range 37-87%) for the longer sequence (difference, P = 0.005, Wilcoxon). The hyperaemia duration above the baseline level was 37 s (inter-quartile range 32-49 s) for the short sequence, and 54 s (inter-quartile range 37-76 s) for the longer sequence (difference, P = 0.001, Wilcoxon). The magnitude of the change in the compression duration was not equalled by the difference in hyperaemia duration, suggesting that the physiological mechanism behind the hyperaemia is unlikely to be due solely to simple accumulation of metabolites, and a myogenic mechanism remains possible. Therapies for peripheral arterial disease need not employ long duration compression, as a greater percentage of time will be spent in hyperaemia with short duration intermittent compression.

Haemodynamic effect of intermittent pneumatic compression of the leg after infrainguinal arterial bypass grafting

Background

Intermittent pneumatic compression (IPC) may increase blood flow through infrainguinal arterial grafts, and has potential clinical application as blood flow velocity attenuation often precedes graft failure. The present study examined the immediate effects of IPC applied to the foot (IPCfoot), the calf (IPCcalf) and to both simultaneously (IPCfoot+calf) on the haemodynamics of infrainguinal bypass grafts.

Methods

Eighteen femoropopliteal and 18 femorodistal autologous vein grafts were studied; all had a resting ankle : brachial pressure index of 0·9 or more. Clinical examination, graft surveillance and measurement of graft haemodynamics were conducted at rest and within 5 s of IPC in each mode using duplex imaging. Outcome measures included peak systolic (PSV), mean (MV) and end diastolic (EDV) velocities, pulsatility index (PI) and volume flow in the graft.

Results

All IPC modes significantly enhanced MV, PSV, EDV and volume flow in both graft types; IPCfoot+calf was the most effective. IPCfoot+calf enhanced median volume flow, MV and PSV in femoropopliteal grafts by 182, 236 and 49 per cent, respectively, and attenuated PI by 61 per cent. Enhancement in femorodistal grafts was 273, 179 and 53 per cent respectively, and PI attenuation was 63 per cent.

Conclusion

IPC was effective in improving infrainguinal graft flow velocity, probably by reducing peripheral resistance. IPC has the potential to reduce the risk of bypass graft thrombosis.

Soft-tissue injury associated with closed fractures: evaluation and management

Determination of the severity of injury to the soft tissues is an important component of patient assessment and affects management of closed fractures. The response of soft tissue to blunt injury involves microvascular and inflammatory processes that produce localized tissue hypoxia and acidosis. Incisions placed through such compromised tissue can lead to wound breakdown and deep infection. Therefore, recognizing the signs of soft-tissue injury is the foundation for successful management of closed fractures. Many treatment options, including splinting, cryotherapy, compression, and delayed surgery, help limit further soft-tissue injury and facilitate its rapid recovery before surgical intervention. Emerging surgical techniques based on improved management have resulted in decreased rates of soft-tissue complications.

The effects of intermittent pneumatic compression on the arterial and venous system of the lower limb: a review

A better understanding of lower limb haemodynamics and the effects of intermittent pneumatic compression on the lower limb has led to an increasing awareness of the potential value of intermittent pneumatic compression in both venous and arterial disease. Intermittent pneumatic compression can be used in both the primary and secondary care settings, with its advantages being further enhanced by excellent patient compliance and very low rate of complications. Intermittent pneumatic compression has a proven role in the prophylaxis of deep vein thrombosis and there is some evidence that it is a useful adjunct in the management of venous ulcer disease. With laboratory and more recent clinical studies demonstrating augmentation of arterial inflow with intermittent pneumatic compression, its use in arterial diseases is being increasingly explored. Further studies are needed to define the precise role of intermittent pneumatic compression in arterial disease but any treatment regimen which reduces the need for referral or intervention in the claudicant or critically ischaemic limb will be a valuable addition to those managing arterial disease.

Evaluation of Pulmonary Arterial Catheter Parameters Utilizing Intermittent Pneumatic Compression Boots in Congestive Heart Failure

The use of intermittent pneumatic compression boots to reduce the risk of deep venous thrombosis is contraindicated in patients with congestive heart failure (CHF) due to a theoretical increase in venous return to the heart and exacerbation of heart failure. This study evaluates intermittent pneumatic compression effects on pulmonary artery catheter parameters in CHF patients. We conducted a prospective within-patient study of CHF patients monitored by pulmonary artery catheterization. Hemodynamic variables were assessed with and without the use of intermittent pneumatic compression boots. A sample size of 18 patients was calculated a priori to obtain an 80 per cent power to detect a mean difference of 10 per cent. Twenty patients were studied; no patient suffered hemodynamic instability during the application of pneumatic compression; no statistically significant change in any hemodynamic parameters was noted. A trend toward decreasing mean arterial blood pressure ( P = 0.057), pulmonary artery wedge pressure ( P = 0.065), and systemic vascular resistance ( P = 0.08) was observed. None were clinically significant. The application of intermittent pneumatic compression to the feet of patients in CHF does not significantly alter central hemodynamic parameters in CHF patients. This study suggests that intermittent pneumatic compression may be used in CHF patients for venous thromboembolic risk reduction.

Role of nitric oxide in vasodilation in upstream muscle during intermittent pneumatic compression

This study investigated the dosage effects of nitric oxide synthase (NOS) inhibitor N(G)-monomethyl-L-arginine (L-NMMA) on intermittent pneumatic compression (IPC)-induced vasodilation in uncompressed upstream muscle and the effects of IPC on endothelial NOS (eNOS) expression in upstream muscle. After L-NMMA infusion, mean arterial pressure increased by 5% from baseline (99.5 +/- 18.7 mmHg; P < 0.05). Heart rate and respiratory rate were not significantly affected. One-hour IPC application on legs induced a 10% dilation from baseline in 10- to 20-microm arterioles and a 10-20% dilation in 21- to 40 microm arterioles and 41- to 70-microm arteries in uncompressed cremaster muscle. IPC-induced vasodilation was dose dependently reduced, abolished, or even reversed by concurrently infused L-NMMA. Moreover, expression of eNOS mRNA in uncompressed cremaster muscle was upregulated to 2 and 2.5 times normal at the end of 1- and 5-h IPC on legs, respectively, and the expression of eNOS protein was upregulated to 1.8 times normal. These increases returned to baseline level after cessation of IPC. The results suggest that eNOS plays an important role in regulating the microcirculation in upstream muscle during IPC.

Nonpharmacologic thromboembolic prophylaxis in total knee arthroplasty

Deep venous thrombosis is the most common complication in patients having elective total knee replacement. Pneumatic compression devices play an important role in the prophylaxis of deep venous thrombosis and effectively decrease the risk of distal deep venous thrombosis. The combination therapy with pharmacologic agents has the benefit of decreasing the rate of proximal deep venous thrombosis and therefore is recommended. In the absence of clinical data, recent in vivo flow studies suggest that calf or combined foot and calf compression are superior to foot compression alone. Epidural anesthesia in comparison with general anesthesia decreases the incidence of thromboembolic disease after total knee arthroplasty. Although hypotensive anesthesia and intraoperative heparin have been proven to substantially lower the incidence of deep venous thrombosis after total hip arthroplasty, the current literature does not support its application during the implantation of a total knee replacement. Pneumatic compression devices are an important part of deep venous thrombosis prophylaxis especially in the early postoperative period considering that pharmacologic anticoagulation is contraindicated in the first 12 hours after spinal anesthesia and in the presence of an epidural line.

Peripheral sympathetic autoregulation in arterial calf inflow enhancement with intermittent pneumatic compression

BACKGROUND

Peroperative mortality, graft failure and balloon angioplasty limitations mitigate against active intervention for claudication. With the exception of exercise programmes, conservative treatments yield limited results. Intermittent pneumatic compression of the foot (IPC(foot)) used daily for over 3 months enhances significantly the walking ability and pressure indices of stable claudicants; this is attributable to the significant calf inflow enhancement with IPC(foot); however, the physiologic mechanisms involved are only partially understood. Aims by comparing the effects of IPC(foot)and postural alteration on calf inflow haemodynamics, this study examines the role of peripheral sympathetic autoregulation, which controls homeostasis in lower limb vessels when posture changes, in the enhancement of calf inflow with IPC(foot)in healthy subjects and claudicants.

MATERIAL AND METHODS

forty-one limbs of healthy subjects (n =34; Group I) and 48 limbs of stable claudicants (Fontaine II) (n =42; Group II) were studied. The volume flow (Q), pulsatility index (PI), mean (mV), peak systolic (PSV) and end diastolic (EDV) velocities were measured in the popliteal artery using duplex ultrasound in: the horizontal position, and on sitting with or without IPC(foot).

RESULTS

in Group II: median Q, mV, PSV and EDV increased by 61%, 53%, 29% and 51% respectively, and PI decreased by 20% as posture changed from sitting to horizontal; with IPC(foot)median Q, mV, PSV and EDV increased by 70%, 58%, 22% and 75% respectively, and PI decreased by 26% (all p < 0.001). In Group I: median Q, mV, PSV and EDV increased by 125%, 115%, 51% and 38% respectively and PI decreased by 30% as posture changed from sitting to horizontal; with IPC(foot)median Q, mV, PSV and EDV increased by 119%, 153%, 23% and 46%, respectively, and PI decreased by 50% (all p < 0.001). The effects of IPC(foot)and postural alteration (from sitting to horizontal) did not differ haemodynamically (p > 0.1) in both groups. Q on lying was similar in Groups I and II. On sitting Q was higher in Group II [p =0.027 (95% CI 1.7, 27 ml/min)].

CONCLUSIONS

the striking similarity in the haemodynamic effects of IPC(foot)and postural alteration in the popliteal artery strongly suggests that the leg inflow enhancement with IPC(foot)is mediated by a transient suspension of peripheral sympathetic autoregulation. In addition to their role as clinical markers of PVD severity, the autoregulatory reflexes of peripheral circulation appear to have functions with significant clinical implications in the management of patients with leg inflow impairment.

Intermittent Pneumatic Compression Devices – Physiological Mechanisms of Action

There are many reports of how IPC is used effectively in the clinical setting; including the prevention of deep venous thrombosis, improvement of circulation in patients with lower extremity arterial diseases, reduction of lymphoedema, and the healing of venous ulcers. However, despite the widely accepted use of IPC, it is still unclear how IPC actually exerts its beneficial effects. The exact physiological mechanisms of action are unknown. The clinical utility of IPC and the putative mechanisms by which IPC could exert its therapeutic effect will be reviewed. The paper will examine the mechanical effects of IPC exerted on the lower extremity, and the subsequent biochemical changes in the circulation. In vitro studies of the effects of mechanical stress such as compressive strain and shear on cultured endothelial cells, and their clinical relevance to IPC will also be reviewed.

Effects of intermittent pneumatic compression of the calf and thigh on arterial calf inflow: a study of normals, claudicants, and grafted arteriopaths

BACKGROUND

Recent data indicate that intermittent pneumatic compression (IPC) of the foot may offer benefits in patients with intermittent claudication exceeding those of standard medications approved by the Food and Drug Administration. IPC of the foot (IPC(foot)) and calf (IPC(calf)) increases flow velocity in infrainguinal arterial bypass grafts and thus may prevent arterial thrombosis. Our aim was to evaluate the acute effects of IPC of the thigh (IPC(thigh)), IPC(calf), and IPC of the thigh and calf (IPC(calf + thigh)) in healthy controls, claudicants, and arteriopaths who have undergone infrainguinal bypass grafting for critical or subcritical limb ischemia.

METHODS

Sixteen limbs of normals (group A), 17 limbs of claudicants (group B), and 16 limbs of arteriopaths (group C) who had undergone infrainguinal autologous revascularization were studied. Blood flow was measured in the limbs of normals and claudicants in the popliteal artery and in the grafts of revascularized limbs by using duplex ultrasonography. Mean velocity (mV), peak systolic velocity, end diastolic velocity (EDV), pulsatility index (PI), and volume flow (Q) were measured in the sitting position at rest and within 10 seconds from the delivery of IPC(thigh), IPC(calf), and IPC(calf + thigh), IPC was delivered at maximum inflation and deflation pressures of 120 mm Hg and 0 mm Hg, respectively; inflation and deflation times of 4 and 16 seconds, respectively; and a proximal inflate delay of 1 second (calf compression preceding that of thigh).

RESULTS

In all 3 groups with all IPC modes, the Q, mV, and EDV increased while PI decreased (P <.05). IPC(thigh) was less effective than IPC(calf), but still increased Q (by 114%, 57%, and 59.8% in groups A, B, and C, respectively) and EDV, while decreasing PI in all 3 groups (P <.05). IPC(calf + thigh) was the most efficient mode, generating an increase in the median Q of 424% in controls, 229% in claudicants, and 317% in grafted arteriopaths. The addition of IPC(thigh) to IPC(calf) increased the mV and Q in group A (P < or = .044); the mV, Q, and EDV in group B (P < or = .03), and mV and PI by 24% and -27% in group C, respectively.

CONCLUSIONS

IPC applied to the thigh, either alone or in combination with IPC(calf), generates native arterial and infrainguinal autologous graft flow enhancement. The paucity of conservative methods available for lower limb blood flow augmentation may allow IPC of the lower limb to emerge as a reliable, noninvasive therapeutic option, ameliorating claudication and assisting infrainguinal bypass graft flow. IPC(thigh) adds to the armamentarium of currently known IPC options (foot or calf) promoting its applicability and efficacy.

The acute effects of intermittent pneumatic foot versus calf versus simultaneous foot and calf compression on popliteal artery hemodynamics: a comparative study

INTRODUCTION

Intermittent pneumatic compression (IPC) is currently being investigated with respect to its effect on distal arterial volume flow in patients with peripheral vascular disease. Recently published data have shown a substantial acute enhancement in arterial calf inflow in response to IPC of the lower limb in both intermittent claudication and leg ischemia.

PURPOSE

The aim of the study was to compare the immediate effects of intermittent pneumatic foot (IPC(foot)) versus calf (IPC(calf)) versus simultaneous foot and calf compression (IPC(foot+calf)) on popliteal artery hemodynamics in patients with intermittent claudication (Fontaine II) and in normal subjects, using duplex ultrasonography. For this purpose, 25 limbs of 20 healthy subjects (age range [mean], 51-74 [64] years) and 31 limbs of 25 claudicants (age range [mean], 56-81 [66.5] years; resting ankle-brachial indices, 0.38-0.75 [0.55]) were examined in the sitting position with and without IPC compression.

RESULTS

Mean popliteal artery flow in healthy subjects increased by 98.8% on application of IPC(foot), 188% with IPC(calf), and 274% with IPC(foot+calf) (all P <.001). Mean flow in claudicants increased by 58% on application of IPC(foot), 132% with IPC(calf), and 174% with IPC(foot+calf) (all P <.001). The mean velocity, peak systolic velocity, and end diastolic velocity displayed a pattern of change similar to that for volume flow in both groups. Pulsatility index decreased in both groups on application of IPC; the lowest values were generated with IPC(foot+calf).

CONCLUSION

Of the three compression modes investigated, IPC(foot+calf) was the most effective means of acutely augmenting arterial calf inflow in arteriopaths and normals. The significant increase in end diastolic velocity and decrease in pulsatility index indicate that peripheral vasodilatation is the central mechanism in this impulse-related flow augmentation. Prospective trials are indicated to determine the clinical potential of the long-term effects of IPC(foot+calf) in patients with symptomatic peripheral vascular disease.

Improving walking ability and ankle brachial pressure indices in symptomatic peripheral vascular disease with intermittent pneumatic foot compression: a prospective controlled study with one-year follow-up

PURPOSE

Intermittent pneumatic foot compression (IPC(foot)) augments arterial leg inflow. It has been suggested that prolonged use of impulse leg compression at home might ameliorate claudication caused by peripheral vascular disease by improving collateral circulation. The purpose of this study was to determine the effect of IPC(foot) treatment on claudication distance and arterial hemodynamics in patients with intermittent claudication caused by peripheral vascular disease.

METHODS

Thirty-seven patients with stable intermittent claudication were admitted to this prospective controlled study. Of these, 25 patients received IPC(foot) (>4 hr/d) for 4.5 months (group 1), and the other 12 patients acted as control patients (group 2). Both groups were advised to exercise unsupervised for a minimum of 1 hour daily and received aspirin (75 mg/d). Groups were matched for age, sex, risk factors, claudication distances, and ankle pressures at baseline. In each patient, initial claudication distance (ICD), absolute claudication distance (ACD), resting ankle brachial index (r-ABI), ankle brachial pressure index after exercise (p-eABI), and popliteal artery volume flow were measured at day 0, 2 weeks, and 1, 2, 3, and 4.5 months. On completion of the treatment period (4.5 months), both groups continued with aspirin (75 mg/d) and unsupervised exercise and were re-examined after 12 months. Data analysis is based on nonparametric statistics, the Wilcoxon signed ranks test, and the Mann-Whitney test for intragroup and intergroup comparisons, respectively. Results are expressed as median and interquartile ranges.

RESULTS

Over the 4.5 months of active treatment, (1) median ICD in group 1 increased by 146% (P <.001), from 78 m (interquartile range, 65-102 m) at baseline to 191.5 m (interquartile range, 127-254 m); ICD did not significantly increase in group 2; (2) median ACD in group 1 improved by 106% (P <.001), from 124 m (interquartile range, 100-160 m) to 255 m (interquartile range, 149-398 m); no significant changes were documented in group 2; (3) median r-ABI in group 1 rose by 18% (P <.001), from 0.57 (interquartile range, 0.48-0.62) to 0.67 (interquartile range, 0.64-0.70); no improvement was noted in group 2; (4) median p-eABI in group 1 rose by 110% (P <.001), from 0.21 (interquartile range, 0.07-0.27) to 0.44 (interquartile range, 0. 36-0.52); no changes were noted in group 2; and (5) median popliteal artery volume flow in group 1 improved by 36% (P <.001), from 100 mL/min (interquartile range, 59-163 mL/min) to 136 mL/min (interquartile range, 99.5-173.4 mL/min); no significant changes were found in group 2. At 4.5 months, ICD, ACD, r-ABI, and p-eABI in group 1 were all significantly better than those in group 2 (P <.01). Twelve months' posttreatment, walking ability and ABIs in group 1 were not statistically different from those at 4.5 months and remained significantly better than those of control subjects.

CONCLUSION

Intermittent pneumatic foot compression used at home for 4.5 months increases claudication distance by over 100%. Associated increases in r-ABI by 18%, p-eABI by 110%, and arterial calf inflow by 36% suggest an improved collateral circulation. Maximum benefit seems to be offered over the initial 3 months. Treatment benefits are maintained 1 year after treatment. A multicenter study is indicated to quantify actual benefits and to demonstrate cost effectiveness.

Effect of intermittent pneumatic foot compression on popliteal artery haemodynamics

PURPOSE

the aim was to investigate the effect of intermittent pneumatic foot compression (IPC(foot)) on popliteal artery haemodynamics in normal individuals and in patients with intermittent claudication due to peripheral vascular disease (PVD) (Fontaine stage II).

MATERIAL AND METHODS

popliteal artery volume flow [vFl], pulsatility index [PI], mean velocity [mV], peak systolic [PSV] and end diastolic velocity [EDV], in 25 limbs of 20 normal subjects and 40 limbs of 32 stable claudicants were obtained in the sitting position before, during and within 30 seconds after the application of IPC(foot)(applied pressure: 120 mmHg; inflation time: 3 seconds; deflation time: 17 seconds) using colour-flow duplex imaging (CFDI). The reproducibility of flow velocity estimations using CFDI in the horizontal [hor] (recovery) and sitting [sit] positions was evaluated in 20 limbs of normal controls and 20 limbs of claudicants.

RESULTS

popliteal artery vFl, mV, PSV and PI measurements were performed with a coefficient of variation (CV) of less than 14.6% among claudicants and of less than 13.3% in normal subjects. EDV is the least reproducible parameter with an overall CV range of 10.2-21.5% in normal controls and 9.1-18.6% in arteriopaths. On application of IPC(foot)popliteal artery vFl increased by 111% in the control group (p<0.001) and by 51% in the claudicants (p<0.001). Within 30 seconds of the cessation of pump action flow decreased significantly in both groups (p<0.001), but maintained a significantly higher level than that at baseline (p<0. 001, in both groups). The mV, PSV and EDV showed a similar pattern of significant changes. Both in normals and claudicants, the PI decreased with IPC(foot)(p<0.001) and increased post-compression; however, it was significantly lower than baseline (p<0.005) within 30 seconds of impulse delivery.

CONCLUSIONS

current CFDI technology enables a reproducible estimation of popliteal artery flow velocities. IPC(foot)can significantly augment arterial calf inflow on an acute basis both in normals and claudicants. The increase of EDV and decrease of PI indicate that attenuation of peripheral resistance to flow is the main mechanism underlying the popliteal artery vFl enhancement on application of IPC(foot). Prospective trials on the long-term effect of IPC(foot)in the management of patients with PVD are indicated from the results of this study.

Enhancing venous outflow in the lower limb with intermittent pneumatic compression. A comparative haemodynamic analysis on the effect of foot vs. calf vs. foot and calf compression

OBJECTIVES

intermittent pneumatic compression (IPC), an established method of deep-vein thrombosis prophylaxis, is also an effective means of leg inflow enhancement, improving the walking capacity and ankle pressure of claudicants, long-term. This study, using duplex ultrasonography, compares the haemodynamic effect of IPC of the (a) foot (at 120 mmHg [IPC(foot/120 mmHg)], and 180 mmHg [IPC(foot/180 mmHg)]), (b) calf (IPC(calf), 120 mmHg) and (c) both simultaneously (IPC(foot+calf), 120 mmHg), on the venous outflow of 20 legs of normals and 25 legs of claudicants.

RESULTS

the peak and mean velocities, volume flow and pulsatility index in the superficial femoral and popliteal veins of both groups increased significantly with all IPC modes (p<0.001). IPC(foot+calf)produced the highest enhancement followed by IPC(calf)(p<0.01), which was more effective (p<0.001) than either IPC(foot/180 mmHg)or IPC(foot/120 mmHg). The venous volume expelled with IPC(calf)and IPC(foot+calf)was 2-2.5 and 3-3.5 times that with IPC(foot/180 mmHg)respectively. Velocity enhancement with IPC was similar between groups and the superficial femoral and popliteal veins. IPC(foot/180 mmHg)produced higher (p<0. 01) flow velocities than IPC(foot/120 mmHg)in both groups and veins examined; however, differences were limited.

CONCLUSIONS

all IPC modes proved effective, IPC(foot+calf)generating the highest venous outflow enhancement. Higher venous volumes expelled with IPC(foot+calf)explain its reported superiority on leg inflow over the other modes. Increase of applied pressure from 120 to 180 mmHg with IPC(foot)offered only a small outflow improvement. Venous haemodynamics at rest and with IPC in claudicants do not differ significantly from those in healthy subjects.

Optimum intermittent pneumatic compression stimulus for lower-limb venous emptying

OBJECTIVE

intermittent pneumatic compression (IPC) of the foot (IPC(foot)), calf (IPC(calf)) or both (IPC(foot+calf)) augments calf inflow, and improves the walking ability and peripheral haemodynamics of claudicants (IPC(foot), IPC(foot+calf)), largely due to venous outflow enhancement. This cohort study, using direct pressure measurements in healthy limbs, determines the optimal combination of frequency (2-4 impulses/minute), applied pressure (60-140 mmHg), mode (IPC(foot)-IPC(calf)-IPC(foot+calf)) and delay time of calf-to-foot impulse (0 s-0.5 s-1 s) that enables IPC to generate an almost complete and sustained decrease in venous pressure.

RESULTS

(a) IPC(foot)at 120 and 80 mmHg generated lower venous pressure than that with 100 and 60 mmHg (p=0.036) respectively, for 2-4 impulses/minute; venous pressure differences between applied pressures of 140 and 120 mmHg or between 80 and 100 mmHg were insignificant. (b) Venous pressure with IPC(calf)at 80 mmHg was lower than that with 60 mmHg (p=0.036) (2-4 cycles/minute); differences in venous pressure between applied pressures of 140 and 100 mmHg or between 120 and 80 mmHg were insignificant. (c) At applied pressures 60-140 mmHg, IPC(foot+calf)with one-second delay generated lower venous pressure than that with half-second delay (p=0.036), the latter being more efficient than zero delay; increasing applied pressures produced lower venous pressure, but differences were small. Venous pressure decreased with increasing IPC frequency (from 2 to 3-4/minute), at applied pressures 60-140 mmHg.

CONCLUSIONS

IPC(foot+calf)at applied 120-140 mmHg, a frequency of 3-4 impulses/minute and one-second delay, provided the optimum intermittent pneumatic stimulus.

Influences of inflation rate and duration on vasodilatory effect by intermittent pneumatic compression in distant skeletal muscle

Previous study has demonstrated that application of intermittent pneumatic compression on legs can cause vasodilation in distant skeletal muscle at the microcirculation level. This study evaluated the influence of inflation rate and peak-pressure duration on the vasodilatory effects of intermittent pneumatic compression. The cremaster muscles of 50 male rats were exposed and divided into five groups of 10 each. A specially designed intermittent pneumatic-compression device was applied in a medial-lateral fashion to both legs of all rats for 60 minutes, with an inflation rate and peak-pressure duration of 0.5 and 5 seconds, respectively, in group A, 5 and 0 seconds in group B, 5 and 5 seconds in group C, 10 and 0 seconds in group D, and 10 and 5 seconds in group E. Diameters of arterial segments were measured in vessels of three size categories (10-20, 21-40, and 41-70 microm) for 120 minutes. The results showed that the greatest increase in diameter was produced by intermittent pneumatic compression with the shortest inflation rate (0.5 seconds). A moderate increase resulted from compression with an inflation rate of 5 seconds, and no effective vasodilation occurred during compression with the longest inflation rate (10 seconds). When the groups with different inflation rates but the same peak-pressure duration were compared, there was a significant difference between any two groups among groups A, C, and E and between groups B and D. When the groups with different peak-pressure durations but the same inflation rate were compared, compression with a peak-pressure duration of 5 seconds caused a generally similar degree of diameter change as did compression without inflation at peak pressure. The findings suggest that inflation rate plays an important role in the modulation of distant microcirculation induced by intermittent pneumatic compression whereas peak-pressure duration does not significantly influence the vasodilatory effects of the compression. This may be due to the fact that rapid inflation produces a significant increase in shear stress on the vascular wall, which stimulates vascular endothelium to release nitric oxide, causing systemic vasodilation.

Sequential foot compression reduces lower limb swelling and pain after total knee arthroplasty

Two common prophylactic measures to prevent deep vein thrombosis (DVT) in patients after orthopedic lower limb surgeries are pneumatic foot and calf compression and antithrombotic treatment. These preventive measures differ in their mechanisms of operation. Antithrombotic agents are aimed to minimize the risk of clot formation, whereas pneumatic foot and calf compression therapy prevents venous stasis, which is a primary factor leading to thrombus formation in patients with leg trauma. DVT, however, is not the only consequence of patient immobility and venous stasis. Additional sequelae of venous stasis include lower limb swelling and pain resulting from the increase in venous pressures and change of normal compartmental circulatory pressures. We therefore hypothesized in the present study that antithrombotic treatment alone is not as effective as combined with pneumatic foot compression in reducing limb swelling and pain. Forty-eight patients after total knee arthroplasty participated in this randomized, controlled study. Low-molecular-weight heparin was the prophylactic measure used for the control group, whereas the pneumatic compression group received low-molecular-weight heparin and foot compression therapy for approximately 7 days after surgery. Lower limb swelling and pain were significantly reduced for the foot compression group in relation to the control group. Ultrasound and venography demonstrated no significant DVT in either group. We conclude that foot compression therapy is an important prophylactic addition to antithrombotic treatment in overcoming the hazardous clinical implications of venous stasis.

Intermittent pneumatic compression of legs increases microcirculation in distant skeletal muscle

Intermittent pneumatic compression has been established as a method of clinically preventing deep vein thrombosis, but the mechanism has not been documented. This study observed the effects of intermittent pneumatic compression of legs on the microcirculation of distant skeletal muscle. The cremaster muscles of 80 male rats were exposed, a specially designed intermittent pneumatic-compression device was applied to both legs for 60 minutes, and the microcirculation of the muscles was assessed by measurement of the vessel diameter in three categories (10-20, 21-40, and 41-70 microm) for 120 minutes. The results showed significant vasodilation in arterial and venous vessels during the application of intermittent pneumatic compression, which disappeared after termination of the compression. The vasodilation reached a maximum 30 minutes after initiation of the compression and could be completely blocked by an inhibitor of nitric oxide synthase, NG-monomethyl-L-arginine (10 micromol/min). A 120-minute infusion of NG-monomethyl-L-arginine, beginning coincident with 60 minutes of intermittent pneumatic compression, resulted in a significant decrease in arterial diameter that remained at almost the same level after termination of the compression. The magnitude of the decrease in diameter in the group treated with intermittent pneumatic compression and NG-monomethyl-L-arginine was comparable with that in the group treated with NG-monomethyl-L-arginine alone. The results imply that the production of nitric oxide is involved in the positive influence of intermittent pneumatic compression on circulation. It is postulated that the rapid increase in venous velocity induced by intermittent pneumatic compression produces strong shear stress on the vascular endothelium, which stimulates an increased release of nitric oxide and thereby causes systemic vasodilation.

The contributions of arterial and venous volumes to increased cutaneous blood flow during leg compression

Intermittent lower extremity compression increases cutaneous blood flow. The source of this increased perfusion and, the influence of physical activity on stimulated foot skin perfusion has not been elucidated. The purpose of this study is to determine the arterial and venous contributions to augmented cutaneous blood flow during foot and leg compression, and to evaluate whether physical activity influenced the response to compression. Fifty limbs from 29 normal volunteers were studied in the sitting position. Their daily physical activity was categorized as active if they exercised > or =3 days/week or sedentary if they exercised < or =3 days/week. Inflatable foot and calf compression cuffs attached to a timed-pressure pump (Art-assist AA 1000, ACI, Inc., San Marcos, CA) were applied to the subject's leg and set to deliver 120 mmHg pressure with a 10-sec deflation cycle. Skin perfusion of the great toe was recorded by a laser Doppler (Laserflo Model BPM 403, TSI, Inc., St. Paul, MN). Total perfusion with compression (A), retrograde venous perfusion (B), and compression artifact (C) was recorded. Mean values for A, B, and C and the differences between the two groups were analyzed using multivariate multiple comparison statistical method. The mean baseline skin perfusion was 3.96 +/- 0.91, and mean total stimulated skin perfusion (A) was 9.23 +/- 2.13. With arterial inflow obliterated and compression applied, mean skin perfusion (B) was 1.96 +/- 0.44. The sedentary group had a mean resting perfusion of 1.64 +/- 0.28 and mean stimulated value (A) of 2.29 +/- 0.37 ml/min/100 gm tissue. The active group had a mean resting perfusion of 28.26 +/- 0.91, and stimulated value (A) of 32.65 +/- 4.47 ml/min/100 gm tissue. These differences in the mean skin perfusion between the two groups were significant. It is concluded that in normals, the majority of increased perfusion is from increased arterial inflow. There is a larger resting foot skin perfusion in active individuals and they have quantitatively greater stimulated inflow compared to sedentary individuals.

Patient assessment and examples of a method of treatment. Use of the circulator boot in peripheral vascular disease

Effective peripheral blood flow is positively related to cardiac output and gravity (part dependent) and inversely related to gravity (part elevated), venous pressure, interstitial fluid pressure, degree of peripheral neuropathy, arteriosclerotic and thrombotic arterial obstructions, and infection. These factors are considered in the operation of the end-diastolic pneumatic boot in the treatment of illustrative patients with lymphedema, venous stasis disease, peripheral arteriosclerosis obliterans, peripheral neuropathy, cellulitis, and osteomyelitis and the failing heart. A method of treatment that includes the use of the boot and the injection of local antibiotics is described.

External leg compression in the treatment of vascular disease

In summary, external compression of the limbs is a mode of therapy that has enjoyed a long history in the treatment of venous and arterial disease. Evidence suggests that its beneficial effects are mediated through enhancement of venous and arterial blood flow, promotion of vasodilation, enhancement of fibrinolysis, and, in the case of obstructive arterial disease, promotion of the development of collateral circulation. The utility of external leg compression in the prevention of deep venous thrombosis and in the management of chronic venous stasis disease has been well documented, and it has become an accepted treatment for these disorders. The use of pneumatic compression in the treatment of atherosclerotic peripheral vascular and cardiovascular disease is less widespread and its indications are less well defined. Though the work of a few investigators in each of these areas shows striking benefits of the technique, further investigation in these areas is warranted. Potential benefits to patients of external limb compression therapy include its non-invasive nature, its ability to be applied in an out-patient setting, and long-term cost savings through possible avoidance of hospitalization and invasive procedures.

Intermittent calf and foot compression increases lower extremity blood flow

PURPOSE

Although foot compression increases foot skin perfusion and calf compression increases popliteal artery blood flow, these compression techniques have not been evaluated in combination. The purpose of this study was to evaluate whether calf and foot compression applied separately and simultaneously increase popliteal artery blood flow and/or foot skin perfusion, and to assess the relative merits of compression in patients with superficial femoral artery occlusion.

METHODS

Twenty-two legs from 12 normal volunteers with ankle/brachial indices (ABIs) > 0.96, and 10 legs from 7 claudicator patients with angiographically documented superficial femoral artery (SFA) occlusion and patent popliteal arteries with ABIs < 0.8 were studied in the sitting position. Calf and foot cuffs connected to a rapidly inflating and deflating timed-pressure pump (Art-Assist-AA 1000; ACI Medical Inc., San Marcos, California) were applied to the subject in the sitting position. Skin blood flow of the great toe was measured with a laser doppler (Laserflo model BPM 403A; TSI Inc., St. Paul, Minnesota), and popliteal artery blood flow was measured using duplex ultrasonography (ATL-Ultramark 9; Advanced Tech Laboratory, Bothell, Washington). Foot and calf compression was applied separately and simultaneously at 120 mm Hg pressure, with a 10-second inflation and 20-second deflation cycle. Popliteal artery blood flow and foot skin perfusion were recorded and the mean of 6 cycles calculated.

RESULTS

Precompression popliteal artery blood flow (mL/min) for volunteers was 38.86 +/- 3.94, and for patients was 86.30 +/- 14.55 (P = 0.001). Precompression foot skin perfusion (mL/min/ 100/g tissue) for volunteers was 1.67 +/- 0.29, and for patients was 4.00 +/- 0.92 (P = 0.01). With the application of calf, foot, and simultaneous calf and foot compression, the popliteal artery blood flow increased in volunteers by 124%, 54%, and 173%, respectively, and in patients by 76%, 13%, and 50%. Foot skin perfusion increased in volunteers by 260%, 500%, and 328%, respectively, and in patients by 116%, 246%, and 188%. Relative increases in popliteal artery blood flow and foot skin perfusion were higher in volunteers compared with patients during compression; however, the absolute values for foot skin perfusion and popliteal artery blood flow were consistently higher in patients.

CONCLUSIONS

Measured in the sitting position, the resting popliteal artery blood flow and foot skin perfusion are greater in patients with SFA occlusion compared with normal volunteers. Following compression, popliteal artery blood flow and foot skin perfusion increased in both groups, but relatively more in volunteers. Increases in popliteal artery blood flow are significantly higher with calf compression than with foot compression for both groups. A patent SFA allows for additive increases in popliteal artery blood flow with simultaneous foot and calf compression in normal persons, whereas this is not observed in patients. However, the increases in foot skin perfusion in patients with an occluded SFA parallel the increases shown in normal volunteers, with separate and simultaneous foot and calf compression.

Augmentation of blood flow in limbs with occlusive arterial disease by intermittent calf compression

PURPOSE

This study was designed to investigate the effect of intermittent calf compression on popliteal arterial blood flow and to see how flow is influenced by position of the subject and by arterial blood pressure at the ankle.

METHODS

Volume flow in the popliteal artery of subjects in the sitting and prone positions was measured with duplex ultrasonography before inflation and immediately after deflation of a pneumatic cuff placed around the calf. Eleven legs of control subjects and 41 legs of patients with symptoms (32% patients with diabetes) with decreased ankle pressure were studied. Cuffs were inflated for 2 seconds at pressures ranging from 20 to 120 mm Hg.

RESULTS

An increase in arterial blood flow of two to eight times (mean 4.4 +/- 2.0) was found on deflation of the cuff in seated control subjects. Little change in flow was observed when the subjects were in the prone position. In seated patients with arterial obstruction, the mean increase in arterial flow was 3.2 +/- 1.6 times the resting flow. Little correlation was found between the maximum increase in flow and the ankle/brachial index.

CONCLUSIONS

An increased arteriovenous pressure gradient accounts for some but not all of the flow increase, much of which must be attributable to transient vasodilatation. Because the increase in flow does not depend on an increased inflow pressure and was not adversely affected by a low resting ankle-brachial pressure index or a low toe-pressure, intermittent external limb compression may deserve investigation as a possible adjunct to the nonoperative treatment of patients with severe arterial insufficiency.

Effects of intermittent pneumatic compression of the foot on the microcirculatory function in arterial disease

OBJECTIVE

The venous pump of the foot assists blood returning to the heart. The aim of this study was to evaluate the effect of mechanical activation of the foot pump on the microcirculation of the skin in patients with peripheral occlusive arterial disease.

DESIGN

Single parallel group comparing patients with arterial disease to normal control subjects.

SETTING

Department of Surgery, the University College and Middlesex Hospital, London, U.K.

SUBJECTS AND MATERIALS

15 patients with peripheral occlusive arterial disease and 15 control subjects. A pneumatic impulse foot pump was applied to the foot.

OUTCOME MEASURES

The Laser Doppler flux (LDF) and transcutaneous oxygen tension (tcPO2) were measured on the big toe with the subject supine, before, during and after a 10 min period of foot pumping. The study was repeated with the subject sitting.

RESULTS

On sitting there is a fall in LDF and rise in tcPO2. Application of intermittent pneumatic compression of the foot in the sitting position resulted in an increase in LDF. In patients, the median percentage increase was 57% and the median difference was 82 arbitrary units (AU) (95% CI 60-130, p < 0.001). In controls, the median percentage increase was 66% and the median difference was 124 AU (95% CI 73-275 p < 0.001). There was a corresponding "further" increase in tcPO2 in both groups of subjects. In patients, the median percentage increase was 8%, in controls the median percentage increase was 10% p < 0.01).

CONCLUSION

We conclude that intermittent pneumatic compression of the foot in the dependent position increases LDF and tcPO2.

The venous footpump: influence on tissue perfusion and prevention of venous thrombosis

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