Epidural analgesia masking a malfunctioning pneumatic compression device.
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Analgesia, Epidural↗
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Results for “Intermittent Pneumatic Compression Devices”
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Intermittent pneumatic compression and deep vein thrombosis prevention. A meta-analysis in postoperative patients.
Our objective was to overview the effectiveness of intermittent pneumatic compression (IPC) devices to prevent deep vein thrombosis (DVT) in postoperative patients, using meta-analysis methodology. We searched the Medline, metaRegister of Controlled Trials, and Cochrane database for studies published between 1970 and October 2004. Our inclusion criteria were: 1) randomized controlled trial of IPC versus no prophylaxis, 2) at least 20 patients per group, 3) at least one diagnostic DVT imaging test in all patients, and 4) clinical follow-up for at least the duration of hospitalization. A total of 2,270 patients were included in 15 eligible studies: 1,125 and 1,145 in the IPC and no prophylaxis group, respectively. The included studies formed a total of 16 treatment groups and were conducted in orthopedic (5), general surgical (4),oncologic (3), neurosurgical (3) and urologic (1) patient populations. In comparison to no prophylaxis, IPC devices reduced the risk of DVT by 60% (relative risk 0.40, 95% CI 0.29 - 0.56; p < 0.001). Contemporary randomized trials should be undertaken to test the utility of IPC in hospitalized medical patients as well as combined pharmacological plus IPC prophylaxis in both medical and surgical patients.
Adolescent↗
Comparison of two intermittent pneumatic compression systems. A hemodynamic study.
AIM: Sequential leg compression has been previously shown to be superior to uniform compression. The aim of our study was to compare the hemodynamic effectiveness of the portable sequential compression device (SCD Express Compression System, Tyco Healthcare Group LP, Mansfield, MA, USA) with a rapid inflation device (VenaFlow, Aircast, Inc, Summit, NJ, USA). The former, by sensing venous refill time, commences compression when the calf veins are refilled. METHODS: The two devices were tested in 12 normal volunteers in the semirecumbent position using duplex ultrasound. Baseline and augmented flow velocity and volume flow were measured at the level of the common femoral vein, above the saphenofemoral junction. Refilling time was determined from velocity recordings of the common femoral vein. Total and peak volume of blood expelled per hour during compression were calculated using flow data and the individual cycling rate. RESULTS: Both devices increased venous flow velocity, up to 3.8 times the baseline (all P<0.001). Refill time of the rapid inflation device was shorter in comparison with the sequential compression device (15+/-2.2 vs 25+/-4 s; P<0.001), suggesting incomplete vein evacuation. The sequential compression device, by augmenting flow throughout a significantly longer compression period per cycle (10.9 s vs 6.3 s), expelled significantly more venous blood (121+/-68 vs 81+/-63 mL; P<0.001). Similarly, the total volume of blood expelled per hour with the sequential compression device was 100% higher than the rapid inflation device (9685+/-5426 vs 4853+/-3658 mL; P<0.001). Although peak velocity enhancement was higher with the rapid inflation device, flow augmentation (a product of average blood flow velocity) was comparable (669+/-367 vs 771+/-574 cm/s; P=0.223) with the sequential compression device, mainly because the rapid inflation device failed to maintain flow enhancement beyond the initial flow surge. CONCLUSIONS: Sequential compression showed hemodynamic superiority compared to a rapid inflation device. This was enhanced further by the sensing of refill time, which resulted in more compression cycles over time. The relative efficacy of the two devices in deep vein thrombosis prevention should be tested in future studies.
Blood Flow Velocity↗
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.
Animals↗
Prevention of air travel-related deep venous thrombosis with mechanical devices: active foot movements produce similar hemodynamic effects.
OBJECTIVE: We compared the hemodynamic effects of different mechanical devices aimed for prevention of travel-related deep venous thrombosis with active foot movements. METHODS: Two battery-operated intermittent pneumatic compression (IPC) devices and three foot and calf muscle pump facilitating devices (PFD) that claimed to prevent travel-related deep venous thrombosis were tested in 17 healthy volunteers on the ground and in 8 of same volunteers during flight. Flow changes during active foot movements were compared with the effects of each of the tested devices. RESULTS: There was no significant difference in hemodynamic effect between PFDs and active foot movements. The hemodynamic effects of IPC devices were significantly less compared with active foot movements. Values obtained during air flights were not significantly different from those obtained on the ground. CONCLUSIONS: Whereas IPC use for prevention of venous stasis during flight can be justified for immobile patients or during sleep, PFDs do not provide additional hemodynamic benefits compared with simple movements of the foot.
Adult↗
Can a new design of pneumatic compression device reduce variations in delivered therapy for the mechanical prophylaxis of thromboembolic disease after total hip arthroplasty?
BACKGROUND: Compression devices have been shown to prevent thromboembolic disease. However, the pressures generated may not be the same as the ones recommended by the manufacturer. The purpose of this study is to investigate a new sequential compression device with feedback to maintain optimal therapy, and to determine whether therapy is improved with this new device. PATIENTS AND METHOD: A series of 50 patients undergoing elective total hip arthroplasty at a major tertiary-care hospital with a special interest in joint replacement were enrolled prospectively. In addition to pharmacological prophylaxis for thromboembolic disease, all patients received compression from a modified device. Maximum pressures generated and the rate of pressure rise in each of the 3 compartments within the device sleeves were measured and the results compared with data from historical controls. RESULTS: We considered therapy to be ideal when in a particular compression cycle all chambers of both right and left sleeves reach within 10% of their target pressures at within 10% of their target pressure rise rates. The average patient received this ideal therapy 88% of the time that the new trial sequential compression device was operating. This represents a dramatic improvement over previous devices. CONCLUSIONS: The new device allows dramatically improved pressures within the device because of a feedback loop that allows dynamic control of each chamber's pressure. Improved consistency of delivery should make it easier to accurately assess the true benefits of mechanical prophylaxis with a sequential compression device.
Adult↗
VenaFlow plus Lovenox vs VenaFlow plus aspirin for thromboembolic disease prophylaxis in total knee arthroplasty.
Two hundred seventy-five patients undergoing unilateral total knee arthroplasty were prospectively randomized to receive spinal epidural anesthesia (SEA), a VenaFlow calf compression device, and enoxaparin (group A) or SEA, VenaFlow, and aspirin (group B). Aspirin was started on the day of surgery, whereas enoxaparin was started 48 hours after surgery. Anticoagulants were continued for 4 weeks after surgery. All patients had an in-hospital ultrasound screening test on postoperative days 3 to 5 and a second follow-up ultrasound 4 to 6 weeks after surgery. The overall deep venous thrombosis rates in groups A and B were 14.1% and 17.8% (P = not significant), respectively. When used in combination with pneumatic compression devices and SEA, enoxaparin was not superior to aspirin in preventing deep venous thrombosis after total knee arthroplasty.
Adult↗
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.
Animals↗
Efficacy of mechanical prophylaxis for venous thromboembolism in patients with brain tumors.
Patients with brain tumors are at considerable risk for the formation of venous thromboemboli. One method of preventing these complications is mechanical prophylaxis in which an external pneumatic compression device and graduated elastic compression stockings are used. Evidence indicates that these devices prevent deep venous thrombosis (DVT) and pulmonary embolism (PE) by limiting venous stasis and increasing fibrinolytic activity at both the local and systemic levels. The authors present evidence for the occurrence of both mechanisms and discuss the use of mechanical compression in the setting of surgery for brain tumors. They also present data proving the efficacy of these devices in patients who undergo craniotomy with motor mapping for resection of glioma and in whom the contralateral leg receives no prophylaxis. Finally, they comment on the use of anticoagulation therapy both in addition to and in place of mechanical prophylaxis.
Anticoagulants↗
Mechanical thromboprophylaxis in critically ill patients: a systematic review and meta-analysis.
OBJECTIVE: To systematically review the randomized trials, observational studies, and survey evidence on compression and pneumatic devices for thromboprophylaxis in intensive care patients. METHODS: Published studies on the use of compression and pneumatic devices in intensive care patients were assessed. A meta-analysis was conducted by using the randomized controlled trials. RESULTS: A total of 21 relevant studies (5 randomized controlled trials, 13 observational studies, and 3 surveys) were found. A total of 811 patients were randomized in the 5 randomized controlled trials; 3421 patients participated in the observational studies. Trauma patients only were enrolled in 4 randomized controlled trials and 4 observational studies. Meta-analysis of 2 randomized controlled trials with similar populations and outcomes revealed that use of compression and pneumatic devices did not reduce the incidence of venous thromboembolism. The pooled risk ratio was 2.37, indicative of favoring the control over the intervention in reducing the deep venous thrombosis; however, the 95% CI of 0.57 to 9.90 indicated no significant differences between the intervention and the control. A range of methodological issues, including bias and confounding variables, make meaningful interpretation of the observational studies difficult. CONCLUSIONS: The limited evidence suggests that use of compressive and pneumatic devices yields results not significantly different from results obtained with no treatment or use of low-molecular-weight heparin. Until large randomized controlled trials are conducted, the role of mechanical approaches to thromboprophylaxis for intensive care patients remains uncertain.
Adolescent↗
Pneumatic pump reduces leg wound complications in cardiac patients.
Leg wound complications at the site of vein harvest for coronary artery bypass graft, although infrequent, cause significant morbidity. Pneumatic pressure therapy is valuable in venous and lymphatic diseases, but its usefulness after leg vein harvest has not been determined. A prospective randomized controlled trial was conducted on 200 patients, half of whom had sequential pneumatic leg pump therapy postoperatively. Wound healing, extent of lower limb edema, patient satisfaction, and the financial implications of pneumatic pressure therapy were assessed. In the study group, 71 patients had satisfactory wound healing vs. 23 in the control group. The leg wound infection rate in the study group was 3% vs. 15% in the control group ( p = 0.003). Lower limb edema was significantly reduced in the study group in the early postoperative period ( p < 0.05), and the mean postoperative length of hospital stay was reduced by 2.6 days in patients given pneumatic pressure therapy ( p = 0.003). The sequential pneumatic leg pump is an effective, inexpensive, and convenient device that reduces leg wound complications after coronary artery bypass grafting.
Coronary Artery Bypass↗
A simple and innovative device to measure arm volume at home for patients with lymphedema after breast cancer.
PURPOSE: We designed an arm volumeter specifically for home use based on the water displacement method. The objective of this study was to determine its accuracy and precision, and compare it with a standard volumeter used in lymphedema clinics worldwide. PATIENTS AND METHODS: Using a standard model hospital volumeter and our own device, we took three consecutive measurements of 11 specially cast cylinders, which had known volumes ranging from 10 mL to 4 L, and measurements of both arms of 15 volunteers. RESULTS: Measurements with both volumeters were highly accurate (R2 = 0.9999) when compared with the known volumes of the cast cylinders, and were strongly correlated (R2 = 0.9974) when each arm volume was compared between volumeters. Measurements with our volumeter were more precise both with the cylinders (average standard deviation [SD], 3.2 v 8 mL; P = .0553) and with the arms (average SD, 11.1 v 19 mL; P = .0034). Whereas the standard volumeter is expensive, fragile (acrylic), and prone to leaks, our volumeter is inexpensive, virtually indestructible, leak proof, and suitable for home use. CONCLUSION: Arm volumes can be measured quickly and accurately at home using a simple, inexpensive, and robust device based on water displacement. Readily accessible arm volumetry at home may have widespread influence on the management of lymphedema after breast cancer.
Anthropometry↗
The efficacy of a new portable sequential compression device (SCD Express) in preventing venous stasis.
OBJECTIVE: It has been previously shown that the SCD Response Compression System, by sensing the postcompression refill time of the lower limbs, delivers more compression cycles over time, resulting in as much as a 76% increase in the total volume of blood expelled per hour. Extended indications for pneumatic compression have necessitated the introduction of portable devices. The aim of our study was to test the hemodynamic effectiveness of a new portable sequential compression system (the SCD Express), which has the ability to detect the individual refill time of the two lower limbs separately. METHODS: This was an open, controlled trial with 30 normal volunteers. The new SCD Express was compared with the SCD Response Compression System in the supine and semirecumbent positions. The refilling time sensed by the device was compared with that determined from velocity recordings of the superficial femoral vein using duplex ultrasonography. Baseline and augmented flow velocity and volume flow, including the total volume of blood expelled per hour during compression with the SCD Express, were compared with those produced by the SCD Response compression system in the same volunteers and positions. RESULTS: Both devices significantly increased venous flow velocity as much as 2.26 times baseline in supine position and 2.67 times baseline in semirecumbent position (all P < .001). There was a linear relationship between duplex ultrasonography-derived refill time and the SCD Express-derived refill time in both the supine (r = 0.39, P = .03) and semirecumbent (r = 0.71, P < .001) positions but not with the SCD Response. Refill time measured by the SCD Express device was significantly shorter and the cycle rate higher in comparison with the SCD Response in both positions. The single-cycle flow velocity and volume flow parameters generated by the two devices were similar in both positions. However, median (interquartile range) total volume of blood expelled per hour was slightly higher with the SCD Express device in the supine position (7206 mL/h [range, 5042-8437] vs 6712 mL/h [4941-10,676]; P = .85) and semirecumbent position (4588 mL/h [range, 3721-6252] vs 4262 mL/h [3520-5831]; P = .22). Peak volume of blood expelled per hour by the SCD Express device in the semirecumbent position was significantly increased by 10% in comparison with the SCD Response (P = .03). CONCLUSIONS: Flow velocity and volume flow enhancement by the SCD Response and SCD Express were essentially similar. The latter, a portable device with optional battery power that detects the individual refill time of the lower limbs separately, is anticipated to be associated with improved overall compliance and therefore optimized thromboprophylaxis. Studies testing its potential for improved efficacy in preventing deep vein thrombosis are justified.
Adolescent↗
[Intermittent compression devices for swelling reduction and thrombosis prophylaxis--a pilot study after total hip replacement. Is the 2 hour daily minimum application sufficient?].
BACKGROUND: The use of intermittent compression devices for thrombosis prophylaxis and the reduction of postoperative swelling are widely accepted. The recommended minimum application of 2 h daily has never been statistically verified. Without evidence based data, the benefit of this costly equipment cannot be maximized. PATIENTS AND METHODS: A randomized clinical trial on 41 patients after total hip replacement was performed. The A-V Impulse System was applied for 2 h a day during the first 5 postoperative days to observe whether this time was sufficiently effective. RESULTS: In the control group, two deep vein thromboses occurred postoperatively, but there were none in the treatment group. Even though two patients from the treatment group had to be excluded from the study because of severe pain, all other parameters including visual analogue pain scale results and limb circumferences were comparable in both groups. CONCLUSION: These preliminary results suggest that pump systems can prevent deep venous thrombosis after hip surgery even when applied for only short intervals over a short period of time. However, large scale confirmatory studies are needed.
Adult↗
Efficacy of deep venous thrombosis prophylaxis in the medical intensive care unit.
The purpose of this study was to determine the incidence of deep venous thrombosis in medical intensive care unit patients receiving deep venous thrombosis prophylaxis. This was a prospective cohort study of 141 consecutive adult patients anticipated to remain in the medical intensive care unit for >48 hours. Deep venous thrombosis prophylaxis was provided using subcutaneous unfractionated heparin or a sequential compression device according to risk-stratified protocol. Compression ultrasound was performed. Fourteen patients (9.9%) developed deep venous thrombosis on follow-up studies. Incidence of deep venous thrombosis was 7.9% per person year (95% confidence interval, 4.8-12.8). Two of 14 developed pulmonary embolism. Eight patients required full anticoagulation with intravenous heparin or coumadin. In-hospital mortality was similar in both groups. Patients with deep venous thrombosis had a statistically higher risk of pulmonary embolism: 14.2% (95% confidence interval, 2.0-43.0) versus 0.0% (95% confidence interval, 0-3; P = .009). Incidence of deep venous thrombosis is high in medical intensive care unit patients receiving standard prophylaxis. Adherence to strict deep venous thrombosis prophylaxis protocol and exploration of other prophylaxis regimens should be pursued.
Adult↗
Secondary spinal cord hypoperfusion of circumscribed areas after injury in rats.
OBJECTIVES: The evaluation of the spatial spread of ischemia following spinal cord injury (SCI) is important for planning therapeutic strategies for secondary injury. The purpose of this study was to investigate in detail the change in regional spinal cord blood flow (rSCBF) after SCI. METHODS: Thirty-four male Wistar rats were used, for which laminectomies of the T11-13 vertebrae were performed. SCI was produced by a directed impact through a laminectomy site at the level of the Th12 using a pneumatic impact device. We measured the sequential and spatial changes of rSCBF using a laser Doppler scanning technique before and after SCI in rats not only at the injured myelomere but also at the circumferent myelomeres. SCBF mapping was carried out before and after SCI on each site. RESULTS: After SCI, the rSCBF value gradually decreased for each site for the SCI group (n=26), while it globally decreased at the epicenter. Moreover, a decrease in SCBF was observed at the caudal and rostral sites. The mean value of the %SCBF 120 minutes after SCI for each site was 63.6+/-2.3% (Th11), 74.4+/-4.5% (Th12), 75.8+/-3.2% (Th13), and was significantly lower for the rostral site compared with the caudal site (p<0.05, one-way analysis of variance). DISCUSSION: This study found that SCBF is significantly decreased not only at the injured myelomere but also at the circumferent myelomeres. Circumferentially extending ischemia after SCI is related to secondary injury after SCI. The improvement in SCBF after SCI, therefore, can be attributed to the treatment of SCI.
Analysis of Variance↗
Reversal of adverse hemodynamic effects of pneumoperitoneum by pressure equilibration.
HYPOTHESIS: The creation of positive-pressure pneumoperitoneum during laparoscopic operations can lead to adverse hemodynamic changes, mainly decreased cardiac output. We hypothesized that pneumatic compression sleeves worn on the legs during pneumoperitoneum could abolish the pressure gradient between the abdominal cavity and the legs and so eliminate these adverse hemodynamic changes. DESIGN: Prospective, randomized, controlled clinical trial with an additional calibration group. SETTING: A regional referral center. PATIENTS: Forty-five consecutive patients undergoing laparoscopic cholecystectomy who developed hemodynamic changes on induction of positive-pressure pneumoperitoneum were randomized to 3 groups. INTERVENTIONS: Low-pressure, nonsequential pneumatic compression sleeves, wrapped around the legs, were used to equilibrate the pressure gradient in the study group and to gradually exceed it in the calibration group. In the control group, no sleeves were used. MAIN OUTCOME MEASURES: Transesophageal Doppler cardiac output, stroke volume, and systemic vascular resistance were monitored noninvasively. RESULTS: The creation of positive-pressure pneumoperitoneum caused a significant decrease of cardiac output and stroke volume and increased systemic vascular resistance. In the experimental groups of patients, pressurizing the sleeves to the pneumoperitoneal pressure caused a significant increase of cardiac output (from 4.82 to 6.74 L/min), increased stroke volume, and decreased systemic vascular resistance (P<.001). This was not seen in the control group. Additional gradual pressure increase in the sleeves of the calibration group produced no further improvement. Releasing the pressure abolished the hemodynamic advantages. CONCLUSIONS: Applying pressure on the legs equivalent to the positive-pressure pneumoperitoneum improves hemodynamic performance during pneumoperitoneum by nullifying the pressure gradient that is responsible for the adverse consequences. This might be of major practical value, especially for cardiac patients undergoing prolonged laparoscopic operations.
Abdominal Cavity↗
Venous thromboembolism prophylaxis in medically ill patients and the development of strategies to improve prophylaxis rates.
Venous thromboembolism (VTE) is common but often unrecognized in medically ill patients. Over the past 5 years, three large-scale placebo-controlled trials enrolling a total of 5500 medically ill patients have highlighted the risk of VTE in this group. These trials have helped to define a specific at-risk patient profile, including those admitted to the hospital with severe congestive heart failure, respiratory illness, acute infection, and inflammatory bowel disease. We performed a retrospective review of patients admitted to the medical service at our tertiary care center to define how common the at-risk medical patient is and to evaluate and improve prophylaxis rates in this patient group. The study was conducted in two phases. Based on admission characteristics, patients were stratified into high-risk or low-risk groups for the development of VTE. During the pre-intervention phase, 75% of patients admitted to the medical service were characterized as increased risk for VTE, yet only 43% of these high-risk patients received prophylaxis of any sort. After interventions designed to increase awareness of VTE, we conducted a second review period. In this post-intervention phase, where 79% of patients were at risk for VTE, prophylaxis rates improved to 72%. Based on these results, we conclude that the majority of patients admitted to the medical service at our tertiary care center constitute a high-risk population that warrants consideration for VTE prophylaxis. Implementation of strategies to improve prophylaxis rates, including educational sessions and risk stratification guidelines, can be successful and improve identification and prophylaxis of this population.
Adolescent↗