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

The long-term arterial assist intermittent pneumatic compression generating venous flow obstruction is responsible for improvement of arterial flow in ischemic legs

Background

There is a large group of patients with ischemia of lower limbs not suitable for surgical reconstruction of arteries treated with the help of external assist by intermittent pneumatic compression devices (IPC). Until recently the generally accepted notion was that by compressing tissues below the knee, veins become emptied, venous pressure drops to zero and the increased arterial-venous pressure gradient enables greater arterial flow. We used a pump that, in contradiction to the “empty veins” devices, limited the limb venous outflow by venous obstructions and in a long period therapy expanded the perfusion vessels and brought about persistent reactive hyperemia.

Aim

To check the toe and calf arterial inflow measured by venous stasis plethysmography and capillary flow velocity during arterial assist IPC in a long-term therapy of ischemic legs.

Material and methods

Eighteen patients (12M, 6F) age 62 to 75 with leg peripheral arterial disease (PAD, Fontaine stage II) were studied. Pneumatic device with two 10cm wide cuffs (foot, calf) (Bio Compression Systems, Moonachie, NJ, USA) inflated to 120 mmHg for 5–6 sec to obstruct the venous flow, deflation time 16 sec, applied for 45–60 min daily for a period of 2 years.

Results

At pump inflation increase in toe arterial pressure, volume, capillary blood flow velocity and one-minute arterial inflow test was observed. Increased toe volume appeared concomitantly with the inflated chamber venous obstruction. Resting pressure in the great saphenous vein increased. The two years therapy showed persistence of the resting limb increased toe capillary flow. Intermittent claudication distance increased by 20–120%. After two years arterial assist TBI increased from 0.2 to 0.6 (range 0.3 to 0.8) (p<0.05 vs pre-therapy). The toe arterial inflow dominated over that in calf skin and muscles, nevertheless, there was prolongation of the claudication distance presumably due to dilatation of exchange vessels also in muscles.

Conclusions

Our arterial assist IPC brought about increase in the toe capillary flow, long lasting dilatation of toe capillaries and extension of painless walking distance. The crucial factor of rhythmic repeated venous outflow obstructions should be taken into account in designing effective assist devices.

A comparison of different modes of pneumatic compression on muscle tissue oxygenation: An intraparticipant, randomised, controlled volunteer study

Intermittent pneumatic compression (IPC) to the lower limbs is widely used as a mechanical means to prevent deep vein thrombosis in hospitalised patients. Due to a theoretical concern about impairing blood flow, thromboembolic-deterrent stockings and IPC are considered contraindicated for patients with peripheral vascular diseases by some clinicians. This study assessed whether IPC would alter peripheral limb muscle tissue oxygenation (StO2), and whether such changes were different during 10 minutes of sequential and single-compartment compressions. Twenty volunteers were randomised to have their left or right arm treated with a sequential or single-compartment IPC for 10 minutes, using the contralateral arm without compression as an intraparticipant control. After a five-minute wash-out period, the procedure was repeated on the same arm using the alternative mode of IPC. Both hands’ thenar muscles StO2 was monitored every two minutes for 10 minutes using the same near-infrared spectroscopy StO2 monitor. Both sequential (3.5%, 95% confidence intervals (CI) 2.7–4.2; p < 0.001) and single-compartment IPC (1.6%, 95% CI 0.4–2.8; p = 0.039) significantly increased muscle StO2 within 10 minutes compared to no compression; and the increments were higher during sequential compressions compared to during single-compartment compressions (2.1%, 95% CI 0.7–3.5; p = 0.023). This mechanistic study showed that both modes of IPC increased upper limb muscle StO2 compared to no compression, but the StO2 increments were higher with the multiple-chamber sequential compressions mode. Contrary to the theoretical concern that IPC may impair peripheral limb tissue oxygenation, our results showed that IPC actually increases oxygenation of the peripheral limb muscles, especially during the sequential compressions mode.

The Use of Transcutaneous Electrical Stimulation of the Calf in Patients Undergoing Infrainguinal Bypass Surgery

BACKGROUND

Infrainguinal bypass surgery is frequently associated with postoperative reperfusion edema of the limb. The etiology is thought to be multifactorial, and there is as yet no standardized treatment protocol for this problem. The primary aim of this study was to assess whether the use of intermittent electrical stimulation of the calf muscles after infrainguinal bypass surgery was effective in reducing the incidence of edema, and the secondary aims to determine the effect of calf muscle stimulation on arterial and venous flow in the operated leg.

METHODS

Forty patients due to undergo infrainguinal bypass surgery for critical lower-limb ischemia (Fontaine grading III-IV or Rutherford grading II-III) were recruited prospectively and randomly divided into the control group, who received the current standard of care, and study group, who received electrical calf muscle stimulation for a 1 hour session twice daily for the first postoperative week. Preoperatively and postoperatively, the leg was measured at 3 predetermined points and a duplex ultrasound scan performed.

RESULTS

The groups were well matched for all parameters. At 1 week, the below knee and calf girth were less in the study group (P = 0.025 and P = 0.043, respectively). Venous flow volumes at rest and on stimulation were higher in the study group (P = 0.010 and P = 0.029, respectively). At 6 weeks, the below knee girth and amount of pitting edema were less in the study group (P = 0.011 and P = 0.014, respectively).

CONCLUSIONS

We conclude that transcutaneous electrical stimulation of the calf decreased lower-limb swelling at 1 and 6 weeks, and increased the venous flow volume at rest and on stimulation at 1 week in patients undergoing infrainguinal bypass surgery for critical ischemia regardless of patient factors or the type of bypass surgery performed or graft used.

Acute oxygenation changes on ischemic foot of a novel intermittent pneumatic compression device and of an existing sequential device in severe peripheral arterial disease

Background

Intermittent pneumatic compression (IPC) improves haemodynamics in peripheral arterial disease (PAD), but its effects on foot perfusion were scarcely studied. In severe PAD patients we measured the foot oxygenation changes evoked by a novel intermittent IPC device (GP), haemodynamics and compliance to the treatment. Reference values were obtained by a sequential foot-calf device (SFC).

Methods

Twenty ischemic limbs (Ankle-Brachial Index = 0.5 ± 0.2) of 12 PAD patients (7 male, age: 74.5 ± 10.8 y) with an interval of 48 ± 2 hours received a 35 minute treatment in supine position with two IPC devices: i) a Gradient Pump (GP), which slowly inflates a single thigh special sleeve and ii) an SFC (ArtAssist^®, ACI Medical, San Marcos, CA, USA), which rapidly inflates two foot-calf sleeves. Main outcome measure: changes of oxygenated haemoglobin at foot (HbO_2foot) by continuous near-infrared spectroscopy recording and quantified as area-under-curve (AUC) for periods of 5 minutes. Other measures: haemodynamics by echo-colour Doppler (time average velocity (TAV) and blood flow (BF) in the popliteal artery and in the femoral vein), patient compliance by a properly developed form.

Results

All patients completed the treatment with GP, 9 with SFC. HbO_2foot during the working phase, considered as average value of the 5 minutes periods, increased with GP (AUC 458 ± 600 to 1216 ± 280) and decreased with SFC (AUC 231 ± 946 to −1088 ± 346), significantly for most periods (P < 0.05). The GP treatment was associated to significant haemodynamic changes from baseline to end of the treatment (TAV = 10.2 ± 3.3 to 13.5 ± 5.5 cm/sec, P = 0.004; BF = 452.0 ± 187.2 to 607.9 ± 237.8 ml/sec, P = 0.0001), not observed with SFC (TAV = 11.2 ± 3.4 to 11.8 ± 4.3 cm/sec; BF = 513.8 ± 203.7 to 505.9 ± 166.5 ml/min, P = n.s.). GP obtained a higher score of patient compliance (P < 0.0001).

Conclusions

A novel IPC thigh device, unlike a traditional SFC device, increased foot oxygenation in severe PAD, together with favourable haemodynamic response and high compliance to the treatment under the present experimental conditions.

Inflatable external upper and lower leg compression improves stroke volume and peripheral perfusion during central hypovolemia in healthy volunteers

Aim: To determine whether external leg compression (ELC) around the legs could prevent and restore central hypovolemia induced by head-up tilt (HUT) maneuver. Materials & methods: The dynamic effect of ELC was determined using 50 cm H2O inflation pressure. HUT was performed without ELC (control model), with ELC inflated before HUT (prevention model) and after HUT (restore model). Results: The decrease in stroke volume (SV) during the prevention model versus control model was 17 ± 3% versus 27 ± 3%. The restore model increased SV by 24 ± 2%. Similarly, peripheral perfusion measured by perfusion index (PI) and tissue oxygen saturation (STO2) was smaller in the prevention model than in the control model (PI: 65 ± 3% vs 79 ± 2%; STO2: 4 ± 1% vs 9 ± 1%). In the restore model, PI increased by 117 ± 24% and STO2 increased by 3 ± 1%. Conclusion: In this study, inflatable ELC around the legs was able to prevent and restore SV and peripheral perfusion in a model of acute central hypovolemia.

Pathophysiology and treatment of edema following femoropopliteal bypass surgery

Substantial lower-limb edema affects the majority of patients who undergo peripheral bypass surgery. Edema has impairing effects on the microvascular and the macrovascular circulation, causes discomfort and might delay the rehabilitation process of the patient. However, the pathophysiology of this edema is not well understood. The Cochrane Library and Medline were used to retrieve literature on edema following peripheral bypass surgery. Factors other than local wound healing alone are suggested in the literature to play a role, given the severity and duration of this edema. Hyperemia, microvascular permeability, reperfusion-associated inflammation and lymphatic disruptions are likely to facilitate the development of edema. Preventive methods could be lymphatic-sparing surgery, intraoperative antioxidative therapy and postoperative elevation. Successful treatment strategies to reduce postoperative edema are based on lymph massage and external compression. In conclusion, the pathophysiology of edema following peripheral surgery is not fully understood, although reperfusion-associated inflammation and lymphatic disruptions are likely to play a crucial role. When future less-invasive techniques prove to be successful, postoperative edema might be minimized. Until then, a careful lymphatic-sparing dissection should be executed when performing a peripheral bypass reconstruction. Postoperatively, the use of compression stockings and leg elevation are currently the golden standards.

Prospective randomized controlled trial to analyze the effects of intermittent pneumatic compression on edema following autologous femoropopliteal bypass surgery

Background

Patients who undergo autologous femoropopliteal bypass surgery develop postoperative edema in the revascularized leg. The effects of intermittent pneumatic compression (IPC) to treat and to prevent postreconstructive edema were examined in this study.

Methods

In a prospective randomized trial, patients were assigned to one of two groups. All patients suffered from peripheral arterial disease, and all were subjected to autologous femoropopliteal bypass reconstruction. Patients in group 1 used a compression stocking (CS) above the knee exerting 18 mmHg (class I) on the leg postoperatively for 1 week (day and night). Patients in group 2 used IPC on the foot postoperatively at night for 1 week. The lower leg circumference was measured preoperatively and at five postoperative time points. A multivariate analysis was done using a mixed model analysis of variance.

Results

A total of 57 patients were analyzed (CS 28; IPC 29). Indications for operation were severe claudication (CS 13; IPC 13), rest pain (10/5), or tissue loss (7/11). Revascularization was performed with either a supragenicular (CS 13; IPC10) or an infragenicular (CS 15; IPC 19) autologous bypass. Leg circumference increased on day 1 (CS/IPC): 0.4%/2.7%, day 4 (2.1%/6.1%), day 7 (2.5%/7.9%), day 14 (4.7%/7.3%), and day 90 (1.0%/3.3%) from baseline (preoperative situation). On days 1, 4, and 7 there was a significant difference in leg circumference between the two treatment groups.

Conclusions

Edema following femoropopliteal bypass surgery occurs in all patients. For the prevention and treatment of that edema the use of a class I CS proved superior to treatment with IPC. The use of CS remains the recommended practice following femoropopliteal bypass surgery.

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.

Long-term effects of endovascular angioplasty on orthostatic vasocutaneous autoregulation in patients with peripheral atherosclerosis

OBJECTIVE

To test the hypothesis that endovascular revascularization of femoropopliteal lesions improves the impaired venoarteriolar response (VAR) in patients with atherosclerosis.

METHODS

We prospectively compared VARs in 15 healthy controls (18 legs) and 14 patients (17 legs) with mild to moderate peripheral arterial disease before and after successful peripheral endovascular angioplasty of femoropopliteal lesions. In all subjects, foot skin blood flow was assessed by laser Doppler flowmetry in the horizontal (HBF) and sitting (SBF) positions. VAR was calculated as (HBF - SBF)/HBF x 100.

RESULTS

In patients with peripheral arterial disease, mean HBF (in arbitrary units [AU]; mean +/- SD) was similar before (25.6 +/- 15.3 AU) and after (27.0 +/- 16.4 AU) angioplasty (P = .67), whereas SBF was significantly lower after than before the endovascular procedure (11.6 +/- 7.7 AU to 18.4 +/- 14.1 AU; P < .05). Intragroup differences between SBF and HBF were significant before and after angioplasty (P < .001). VAR was higher after angioplasty (55.1% +/- 21.2%) compared with VAR before intervention (33.4% +/- 20.2%; P = .015). Although VAR increased after the intervention, VAR was still lower than in healthy controls (68.4% +/- 20.5%; P = .025). During the 6 months of follow-up, the ankle-brachial index and VAR remained unchanged (P > .05).

CONCLUSIONS

Patients with mild to moderate peripheral arterial disease have an impaired orthostatic autoregulation that improves after successful endovascular revascularization of femoropopliteal obstructive lesions. The effect on VAR is sustained in the absence of restenosis.

MR angiography of the hand with subsystolic cuff-compression optimization of injection parameters

OBJECTIVE

The purpose of our study was to assess the impact of various injection rates on contrast-enhanced high-resolution 3D MR angiography of the hand.

MATERIALS AND METHODS

Ten healthy individuals (mean age, 24.4 years; range, 20-27 years) underwent 3D contrast-enhanced MR angiography of both hands. Starting 3 minutes before data acquisition, subsystolic upper arm cuff compression was applied unilaterally. A 1.5-T whole-body scanner with 3D gradient-echo sequence was used. Seven data sets (20 seconds) were obtained consecutively. I.v. contrast material of 0.1 mg/kg of body weight of gadobutrol was injected at rates of 0.5, 1.0, and 1.5 mL/s. For both hands, quantitative data evaluation was performed with contrast-to-noise ratio (CNR) in the radial, ulnar, palmar, and digital arteries and veins. Qualitative assessment of the arterial visualization score and venous contamination score was rated by two experienced radiologists using a 4-point scale.

RESULTS

The lowest venous contamination score (CNR and reviewers' assessment) was observed with an injection rate of 0.5 mL/s (p < 0.05). For the arterial signal, the reviewers' assessment was that an injection rate of 0.5 mL/s was best (p = 0.08). Compression yielded a significantly lower venous contamination score for the compressed side than for the noncompressed side for flow rates of 0.5 mL/s and 1.0 mL/s (p < 0.05).

CONCLUSION

Image quality of hand MR angiography was better with cuff compression. A flow rate of 0.5 mL/s yielded a good CNR and a significantly lower venous contamination score than the other flow rates.

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.