- Email: [email protected]
Superior hemodynamic performance of a thigh-length versus knee-length intermittent pneumatic compression device
Superior hemodynamic performance of a thigh-length versus knee-length intermittent pneumatic compression device Robert B. Patterson, MD, RVT, and Paul Cardullo, RN, MS, RVT, Providence, RI Objective: There is a lack of consensus regarding which length of intermittent pneumatic compression (IPC) device provides optimal thromboprophylaxis. This trial was conducted to compare hemodynamic performance of a thigh-length and knee-length IPC device. The hypothesis is that thigh-length IPC will be more efficient in preventing stasis. Methods: This single-center trial tested the thigh-length sleeve (TLS) and knee-length sleeve (KLS) in 47 healthy volunteers. Peak systolic velocity and total volume flow were measured at rest and during the 11-second compression cycle. Measurements were obtained at the popliteal vein for the KLS and at the common femoral vein for the TLS.
Results: The study was completed by 47 volunteers (32 women, 15 men), who were a mean age of 39.7 years (range, 18-68 years). There was a statistically significant difference in augmented total volume flow and peak systolic velocity between the KLS and TLS favoring the TLS: median total volume flow was 357.54 mL/min for the KLS vs 668.21 mL/min for the TLS (P < .0001), and median peak systolic velocity was 47.70 cm/s for the KLS vs 58.47 cm/s for the TLS (P [ .0019). Conclusions: This trial suggests that the improved hemodynamic effects of a thigh-length IPC system may provide superior thromboprophylaxis to a knee-length IPC. (J Vasc Surg: Venous and Lym Dis 2013;1:276-9.)
Venous thromboembolism (VTE) consists of deep vein thrombosis (DVT) and pulmonary embolism (PE). Despite advances in pharmacologic and mechanical prophylaxis, VTE remains a major contributor to morbidity, mortality, and health care costs.1 Most hospitalized patients have at least one risk factor for VTE, and many patients have multiple risk factors.2 A review of data from the Agency for Healthcare Research and Quality Patient Safety Indicators found that postoperative VTE increased length of stay by an average of 5.36 days and resulted in a statistically significant increase in cost and patient mortality.3 The Centers for Medicare and Medicaid Services Surgical Care Improvement Project has identified prophylaxis of VTE as a primary component of quality.4 Intermittent pneumatic compression (IPC) in conjunction with pharmaceutical prophylaxis is a recommended method of mechanical prophylaxis for high-risk patients. Furthermore, the use of IPC devices is recommended for patients at risk of bleeding who cannot receive pharmaceutical prophylaxis.5 Use of IPC devices has been shown to reduce the risk of VTE by 60% compared with no
prophylaxis,6 and a meta-analysis concluded that combined modalities offer optimal protection for patients at high risk for VTE.7 Mechanical VTE prophylaxis options include rapid and slow foot compression, as well as knee-length and thighlength IPC sleeves. Currently, no consensus is available to guide the clinician’s selection of an IPC device. Prior publications have suggested that a thigh-length device may optimally reduce stasis, although a meta-analysis comparing the clinical performance of knee-length and thigh-length IPC devices was inconclusive in establishing clinical superiority of thigh-length devices.8 Hemodynamic testing is a well-established method of evaluating IPC devices.9,10 The method allows comparative characterization of the movement of blood in the legs using ultrasound technology. We postulated that the flow augmentation of a thigh-length IPC would be greater than a knee-length IPC using the same compression algorithm.
From the Warren Alpert School of Medicine, Brown University. Author conflict of interest: This study was funded by Covidien Cardinal Hemodynamic Study 383.23. Editorial support was provided by Clinical Affairs at Covidien. Presented at the Twelfth Annual Meeting of the European Venous Forum, Ljubljana, Slovenia, July 1, 2011. Reprint requests: Robert B. Patterson, MD, RVT, Providence Surgical Care Group, 486 Silver Spring St, Providence, RI (e-mail: robert_patterson@ brown.edu). The editors and reviewers of this article have no relevant financial relationships to disclose per the Journal policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 2213-333X/$36.00 Copyright Ó 2013 by the Society for Vascular Surgery. http://dx.doi.org/10.1016/j.jvsv.2012.09.009
276
METHODS This study was approved by the Institutional Review Board. All participants signed informed consent before study procedures. Study design. This study was a randomized, singlecenter, crossover trial that compared the hemodynamic performance of the knee-length vs the thigh-length IPC sleeves (both manufactured by Covidien, Mansfield, Mass). Total blood volume flow and peak systolic velocity were the study variables, calculated by the method of Kakkos et al.11 Participants. A preliminary study of 19 volunteers was performed to determine the sample size necessary to detect a difference in the primary end point of $150 mL/min change in blood volume flow or >15 cm/s change in
JOURNAL OF VASCULAR SURGERY: VENOUS AND LYMPHATIC DISORDERS Volume 1, Number 3
peak systolic blood velocity. Power was fixed at 80% using a two-sided 0.05 Wilcoxon test, assuming a Gaussian distribution. This preliminary study showed a sample size of 47 was needed to detect a difference in peak systolic blood velocity. The study enrolled healthy adult men and women who properly fit into size medium IPC sleeves. Exclusion criteria included a local condition precluding sleeve placement (ie, infection, dermatitis, surgical wound), clinical arterial disease with absent pedal pulses, peripheral edema, heart failure, pregnant or breastfeeding women, and active VTE or a history of VTE. Materials. Kendall SCD knee-length soft sleeves model 5329 (KLS) and the Kendall SCD thigh-length soft sleeves model 5330 (TLS; both Covidien) were used throughout the study. The sleeves consist of three air chambers that deliver circumferential compression to the legs. The KLS has three chambers in the calf, and the TLS has two calf chambers and one thigh chamber (Fig 1). The sleeves were inflated sequentially to a controlled pressure of 45 mm Hg at the lower calf, 40 mm Hg in the middle bladder, and 30 mm Hg at the top bladder, with an 11second compression cycle and 60-second decompression using a compatible Kendall SCD 5325 Compression System Controller (Covidien; Fig 2). This controller, with a fixed rather than variable venous refill time, was used to minimize intersubject variability potentially seen with a variable refill time device. Procedures. Participants fasted and abstained from caffeine and smoking for a minimum of 1 hour before the study. DVT screening was performed by ultrasound imaging with the participants supine. After negative DVT screening, IPC sleeves were placed on both legs (to avoid alarming of the Kendall SCD 5325 controller), with only
Patterson and Cardullo 277
Fig 2. Compression pattern of knee-length and thigh-length intermittent pneumatic compression (IPC) devices. (See Fig 1 for A-C bladder configuration.)
the right leg used for study measurements. The order of sleeve placement (TLS or KLS) was randomized based on a previously assigned randomization schedule. A common controller unit was used throughout the study to avoid any potential source of variability. All measurements were performed with a Philips HD15 color Doppler ultrasound system (Philips Healthcare, Andover, Mass). To avoid interoperator variability, the same sonographer conducted all studies. A linear array L12-3 transducer was used to image the common femoral vein for the TLS or the popliteal vein for the KLS in the longitudinal plane. The sample volume was positioned in the middle lumen at a 60 angle to flow. Peak systolic velocity (PSV) in cm/s, time averaged velocity (TAV) in cm/s, vein diameter in mm (popliteal for KLS and common femoral for TLS), and total volume flow (TVF) in mL/min were recorded at baseline for 11 seconds after 5 minutes of rest. The Kendall SCD 5325 controller was then activated, and a minimum of five compression cycles were performed before data acquisition. Five consecutive measurements of PSV, TAV, and TVF were obtained at the target vein after each compression cycle to calculate the mean for the parameters. Measurements of PSV and TVF were made over the 11 seconds of compression. After a 15-minute rest period, the IPC device crossover occurred, and the study parameters were tested with the other IPC device (KLS or TLS), according to the same methods described above. Data analysis. A nonparametric one-sample (paired) Wilcoxon signed-rank test was used to compare the paired KLS and TLS measurements for the study end points of change in PSV and change in blood TVF moved per unit of time.
RESULTS Fig 1. Knee-length and thigh-length intermittent pneumatic compression (IPC) devices, with bladder configuration.
Study enrollment occurred between June 30, 2010, and September 17, 2010. A total of 47 volunteers (32
278 Patterson and Cardullo
JOURNAL OF VASCULAR SURGERY: VENOUS AND LYMPHATIC DISORDERS July 2013
women and 15 men), who were a mean age of 39.7 years (range, 18-68 years), completed the study. Median resting TVF was 116.05 (652.28) mL/min for the KLS and 314.53 (6188.13) mL/min for the TLS. The knee and thigh configurations both had a substantial increase in TVF with compression (Fig 3), with a difference in median values (compression e resting) of 357.54 (6 231.07) mL/min for the KLS and 668.21 (6 320.23) mL/min for the TLS (P < .0001). Similarly, there was a significant increase in the difference in median PSV for both sleeve lengths, with the TLS having a greater median velocity increase (58.47 6 29.65 cm/s) compared with the KLS (47.70 6 18.79 cm/s; P ¼ .0019; Fig 4). In all of these measurements, variability (in parentheses) is expressed as the interquartile range, that is, the difference between the 75th and 25th percentiles of the distribution. DISCUSSION Few studies have directly compared the performance of knee-length and thigh-length sequential compression devices. However, a few studies have reported results for knee-length vs thigh-length compression stockings. The Clots in Legs or Stockings After Stroke (CLOTS) 2 trial demonstrated superiority of thigh-length stockings in VTE prophylaxis in a stroke population.12 Two recent meta-analyses found a relative risk reduction in VTE with thigh-length stockings compared with knee-length stockings that did not reach statistical significance.13,14 We have demonstrated that use of a thigh-length IPC device significantly increases TVF and TAV compared with a knee-length IPC in healthy volunteers. Although a VTE end point study would be the ideal way to study IPC device performance, due to the large sample sizes necessary to study clinical performance of IPC devices with DVT and PE end points, such studies are logistically difficult to conduct. As with our study, most prior studies evaluating venous hemodynamic changes with IPC devices have been performed in healthy volunteers. Such studies use hemodynamic measures as a surrogate for clinical efficacy. Numerous publications have stressed that the efficacy of IPC devices of any configuration is directly related to compliance of patients and nursing staff in the application
Fig 4. Peak systolic velocity of knee-length and thigh-length intermittent pneumatic compression (IPC) devices. aP ¼ .0019.
of these devices. Thigh-high devices are commonly demonstrated to have a lower satisfaction rating by patients and nursing personnel.15,16 Our results suggest that thighlength devices may offer improved protection against VTE through superior reduction in venous stasis. Education of patients and nursing personnel about these benefits may lead to increased compliance and improved IPC efficacy with a thigh-length device. In addition, development of more comfortable compression sleeves may improve compliance and patient tolerance of thigh-length sleeves.17 Several potential shortcomings of these data exist. First, the study was conducted in healthy individuals. Although patients who receive the device are typically compromised and in a hospital setting, a hemodynamic study by Kakkos et al9 demonstrated a similar hemodynamic response between healthy individuals and those with chronic venous insufficiency, suggesting generalizability of our results. Second, the knee and thigh IPC devices were insonated at different sites. The sites of insonation of the common femoral vein for the thigh-length device and the popliteal vein for the knee-length device were selected to minimize the potential contribution of the capacitance of the thigh deep venous system in diminishing the augmentation of PSV and TVF in the KLS. Because tissue volume under compression appears to be directly correlated with augmentation of hemodynamics with IPC, we felt that insonation closest to the region of compression would provide the most rigorous comparison of the two devices. CONCLUSIONS
Fig 3. Total volume flow of knee-length and thigh-length intermittent pneumatic compression (IPC) devices. aP < .0001.
Using hemodynamic data as a surrogate for clinical effectiveness, this trial suggests that the improved hemodynamic effects of the thigh-length IPC device may provide superior thromboprophylaxis to a knee-length IPC device. The hemodynamic superiority of the thigh-length IPC device compared with the knee-length IPC device, as measured by augmented TVF and PSV, was highly significant in this study. We postulate that the increased volume of compressed tissue accounts for the findings, consistent with a study of foot vs foot and calf compressive devices.18
JOURNAL OF VASCULAR SURGERY: VENOUS AND LYMPHATIC DISORDERS Volume 1, Number 3
The execution of a large prospective, controlled, multicenter clinical trial to confirm the results of this trial would be ideal; however, completion of these evaluations is limited by their considerable resource requirements.
8.
9.
AUTHOR CONTRIBUTIONS Conception and design: RP Analysis and interpretation: RP, PC Data collection: PC Writing the article: RP Critical revision of the article: RP, PC Final approval of the article: RP Statistical analysis: RP Obtained funding: RP, PC Overall responsibility: RP REFERENCES 1. Geerts WH, Bergqvist D, Pineo GF, Heit JA, Samama CM, Lassen MR, et al. Prevention of venous thromboembolism: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008;133(6 Suppl):381-453S. 2. Anderson FA Jr, Wheeler HB. Physician practices in the management of venous thromboembolism: a community-wide survey. J Vasc Surg 1992;16:707-14. 3. Zhan C, Miller MR. Excess length of stay, charges, and mortality attributable to medical injuries during hospitalization. JAMA 2003;290:1868-74. 4. Hospital Quality Alliance (HQA) 2004-2007 measure build-out table. Centers for Medicare & Medicaid Services Web site. Available at: http://www.cms.gov/HospitalQualityInits/downloads/HospitalHQA 2004_2007200512.pdf. Accessed November 11, 2011. 5. Guyatt GH, Akl EA, Crowther M, Gutterman DD, Schünemann HJ. Antithrombotic therapy and prevention of thrombosis: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (9th Edition). Chest 2012;14(Suppl):7-47S. 6. Urbankova J, Quiroz R, Kucher N, Goldhaber SZ. Intermittent pneumatic compression and deep vein thrombosis prevention. A metaanalysis in postoperative patients. Thromb Haemost 2005;94:1181-5. 7. Kakkos SK, Caprini JA, Geroulakos G, Nicolaides AN, Stansby GP, Reddy DJ. Combined intermittent pneumatic leg compression and
10.
11.
12.
13.
14.
15.
16.
17.
18.
Patterson and Cardullo 279
pharmacological prophylaxis for prevention of venous thromboembolism in high-risk patients. Cochrane Database Syst Rev 2008:CD005258. Vanek VW. Meta-analysis of effectiveness of intermittent pneumatic compression devices with a comparison of thigh-high to knee-high sleeves. Am Surg 1998;64:1050-8. Kakkos SK, Szendro G, Griffin M, Sabetai MM, Nicolaides AN. Improved hemodynamic venous effectiveness and associated clinical correlations of a new intermittent pneumatic compression system in patients with chronic venous insufficiency. J Vasc Surg 2001;34: 915-22. Kakkos SK, Griffin M, Geroulakos G, Nicolaides AN. The efficacy of a new portable sequential compression device (SCD Express) in preventing venous stasis. J Vasc Surg 2005;42:296-303. Kakkos S, Szendro G, Griffin M, Daskalopoulou SS, Nicolaides A. The efficacy of the new SCD Response Compression system in the prevention of venous stasis. J Vasc Surg 2000;32:932-40. CLOTS (Clots in Legs Or sTockings after Stroke) Trial Collaboration. Thigh-length versus below-knee stockings for deep venous thrombosis prophylaxis after stroke: a randomized trial. Ann Intern Med 2010;153: 553-62. Loomba RS, Arora RR, Chandrasekar S, Shah PH. Thigh-length versus knee-length compression stockings for deep vein thrombosis prophylaxis in the inpatient setting. Blood Coagul Fibrinolysis 2012;23: 168-71. Sajid MS, Desai M, Morris RW, Hamilton G. Knee length versus thigh length graduated compression stockings for prevention of deep vein thrombosis in postoperative surgical patients. Cochrane Database Syst Rev 2012;(5):CD007162. Hilleren-Listerud AE. Graduated compression stocking and intermittent pneumatic compression device length selection. Clin Nurse Spec 2009;23:21-4. Proctor MC, Greenfield LJ, Wakefield TW, Zajkowski PJ. A clinical comparison of pneumatic compression devices: the basis for selection. J Vasc Surg 2001;34:459-63; discussion: 463-4. Conway D, Quatrara B. DVT prophylaxis with a new compression sleeve following surgery: the role of nurses and the importance of patient compliance. Poster/abstract presentation, NAON May 2011. Delis KT, Slimani G, Hafez HM, Nicolaides AN. 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. Eur J Vasc Endovasc Surg 2000;19:250-60.
Submitted Jul 8, 2012; accepted Sep 22, 2012.
Results: The study was completed by 47 volunteers (32 women, 15 men), who were a mean age of 39.7 years (range, 18-68 years). There was a statistically significant difference in augmented total volume flow and peak systolic velocity between the KLS and TLS favoring the TLS: median total volume flow was 357.54 mL/min for the KLS vs 668.21 mL/min for the TLS (P < .0001), and median peak systolic velocity was 47.70 cm/s for the KLS vs 58.47 cm/s for the TLS (P [ .0019). Conclusions: This trial suggests that the improved hemodynamic effects of a thigh-length IPC system may provide superior thromboprophylaxis to a knee-length IPC. (J Vasc Surg: Venous and Lym Dis 2013;1:276-9.)
Venous thromboembolism (VTE) consists of deep vein thrombosis (DVT) and pulmonary embolism (PE). Despite advances in pharmacologic and mechanical prophylaxis, VTE remains a major contributor to morbidity, mortality, and health care costs.1 Most hospitalized patients have at least one risk factor for VTE, and many patients have multiple risk factors.2 A review of data from the Agency for Healthcare Research and Quality Patient Safety Indicators found that postoperative VTE increased length of stay by an average of 5.36 days and resulted in a statistically significant increase in cost and patient mortality.3 The Centers for Medicare and Medicaid Services Surgical Care Improvement Project has identified prophylaxis of VTE as a primary component of quality.4 Intermittent pneumatic compression (IPC) in conjunction with pharmaceutical prophylaxis is a recommended method of mechanical prophylaxis for high-risk patients. Furthermore, the use of IPC devices is recommended for patients at risk of bleeding who cannot receive pharmaceutical prophylaxis.5 Use of IPC devices has been shown to reduce the risk of VTE by 60% compared with no
prophylaxis,6 and a meta-analysis concluded that combined modalities offer optimal protection for patients at high risk for VTE.7 Mechanical VTE prophylaxis options include rapid and slow foot compression, as well as knee-length and thighlength IPC sleeves. Currently, no consensus is available to guide the clinician’s selection of an IPC device. Prior publications have suggested that a thigh-length device may optimally reduce stasis, although a meta-analysis comparing the clinical performance of knee-length and thigh-length IPC devices was inconclusive in establishing clinical superiority of thigh-length devices.8 Hemodynamic testing is a well-established method of evaluating IPC devices.9,10 The method allows comparative characterization of the movement of blood in the legs using ultrasound technology. We postulated that the flow augmentation of a thigh-length IPC would be greater than a knee-length IPC using the same compression algorithm.
From the Warren Alpert School of Medicine, Brown University. Author conflict of interest: This study was funded by Covidien Cardinal Hemodynamic Study 383.23. Editorial support was provided by Clinical Affairs at Covidien. Presented at the Twelfth Annual Meeting of the European Venous Forum, Ljubljana, Slovenia, July 1, 2011. Reprint requests: Robert B. Patterson, MD, RVT, Providence Surgical Care Group, 486 Silver Spring St, Providence, RI (e-mail: robert_patterson@ brown.edu). The editors and reviewers of this article have no relevant financial relationships to disclose per the Journal policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 2213-333X/$36.00 Copyright Ó 2013 by the Society for Vascular Surgery. http://dx.doi.org/10.1016/j.jvsv.2012.09.009
276
METHODS This study was approved by the Institutional Review Board. All participants signed informed consent before study procedures. Study design. This study was a randomized, singlecenter, crossover trial that compared the hemodynamic performance of the knee-length vs the thigh-length IPC sleeves (both manufactured by Covidien, Mansfield, Mass). Total blood volume flow and peak systolic velocity were the study variables, calculated by the method of Kakkos et al.11 Participants. A preliminary study of 19 volunteers was performed to determine the sample size necessary to detect a difference in the primary end point of $150 mL/min change in blood volume flow or >15 cm/s change in
JOURNAL OF VASCULAR SURGERY: VENOUS AND LYMPHATIC DISORDERS Volume 1, Number 3
peak systolic blood velocity. Power was fixed at 80% using a two-sided 0.05 Wilcoxon test, assuming a Gaussian distribution. This preliminary study showed a sample size of 47 was needed to detect a difference in peak systolic blood velocity. The study enrolled healthy adult men and women who properly fit into size medium IPC sleeves. Exclusion criteria included a local condition precluding sleeve placement (ie, infection, dermatitis, surgical wound), clinical arterial disease with absent pedal pulses, peripheral edema, heart failure, pregnant or breastfeeding women, and active VTE or a history of VTE. Materials. Kendall SCD knee-length soft sleeves model 5329 (KLS) and the Kendall SCD thigh-length soft sleeves model 5330 (TLS; both Covidien) were used throughout the study. The sleeves consist of three air chambers that deliver circumferential compression to the legs. The KLS has three chambers in the calf, and the TLS has two calf chambers and one thigh chamber (Fig 1). The sleeves were inflated sequentially to a controlled pressure of 45 mm Hg at the lower calf, 40 mm Hg in the middle bladder, and 30 mm Hg at the top bladder, with an 11second compression cycle and 60-second decompression using a compatible Kendall SCD 5325 Compression System Controller (Covidien; Fig 2). This controller, with a fixed rather than variable venous refill time, was used to minimize intersubject variability potentially seen with a variable refill time device. Procedures. Participants fasted and abstained from caffeine and smoking for a minimum of 1 hour before the study. DVT screening was performed by ultrasound imaging with the participants supine. After negative DVT screening, IPC sleeves were placed on both legs (to avoid alarming of the Kendall SCD 5325 controller), with only
Patterson and Cardullo 277
Fig 2. Compression pattern of knee-length and thigh-length intermittent pneumatic compression (IPC) devices. (See Fig 1 for A-C bladder configuration.)
the right leg used for study measurements. The order of sleeve placement (TLS or KLS) was randomized based on a previously assigned randomization schedule. A common controller unit was used throughout the study to avoid any potential source of variability. All measurements were performed with a Philips HD15 color Doppler ultrasound system (Philips Healthcare, Andover, Mass). To avoid interoperator variability, the same sonographer conducted all studies. A linear array L12-3 transducer was used to image the common femoral vein for the TLS or the popliteal vein for the KLS in the longitudinal plane. The sample volume was positioned in the middle lumen at a 60 angle to flow. Peak systolic velocity (PSV) in cm/s, time averaged velocity (TAV) in cm/s, vein diameter in mm (popliteal for KLS and common femoral for TLS), and total volume flow (TVF) in mL/min were recorded at baseline for 11 seconds after 5 minutes of rest. The Kendall SCD 5325 controller was then activated, and a minimum of five compression cycles were performed before data acquisition. Five consecutive measurements of PSV, TAV, and TVF were obtained at the target vein after each compression cycle to calculate the mean for the parameters. Measurements of PSV and TVF were made over the 11 seconds of compression. After a 15-minute rest period, the IPC device crossover occurred, and the study parameters were tested with the other IPC device (KLS or TLS), according to the same methods described above. Data analysis. A nonparametric one-sample (paired) Wilcoxon signed-rank test was used to compare the paired KLS and TLS measurements for the study end points of change in PSV and change in blood TVF moved per unit of time.
RESULTS Fig 1. Knee-length and thigh-length intermittent pneumatic compression (IPC) devices, with bladder configuration.
Study enrollment occurred between June 30, 2010, and September 17, 2010. A total of 47 volunteers (32
278 Patterson and Cardullo
JOURNAL OF VASCULAR SURGERY: VENOUS AND LYMPHATIC DISORDERS July 2013
women and 15 men), who were a mean age of 39.7 years (range, 18-68 years), completed the study. Median resting TVF was 116.05 (652.28) mL/min for the KLS and 314.53 (6188.13) mL/min for the TLS. The knee and thigh configurations both had a substantial increase in TVF with compression (Fig 3), with a difference in median values (compression e resting) of 357.54 (6 231.07) mL/min for the KLS and 668.21 (6 320.23) mL/min for the TLS (P < .0001). Similarly, there was a significant increase in the difference in median PSV for both sleeve lengths, with the TLS having a greater median velocity increase (58.47 6 29.65 cm/s) compared with the KLS (47.70 6 18.79 cm/s; P ¼ .0019; Fig 4). In all of these measurements, variability (in parentheses) is expressed as the interquartile range, that is, the difference between the 75th and 25th percentiles of the distribution. DISCUSSION Few studies have directly compared the performance of knee-length and thigh-length sequential compression devices. However, a few studies have reported results for knee-length vs thigh-length compression stockings. The Clots in Legs or Stockings After Stroke (CLOTS) 2 trial demonstrated superiority of thigh-length stockings in VTE prophylaxis in a stroke population.12 Two recent meta-analyses found a relative risk reduction in VTE with thigh-length stockings compared with knee-length stockings that did not reach statistical significance.13,14 We have demonstrated that use of a thigh-length IPC device significantly increases TVF and TAV compared with a knee-length IPC in healthy volunteers. Although a VTE end point study would be the ideal way to study IPC device performance, due to the large sample sizes necessary to study clinical performance of IPC devices with DVT and PE end points, such studies are logistically difficult to conduct. As with our study, most prior studies evaluating venous hemodynamic changes with IPC devices have been performed in healthy volunteers. Such studies use hemodynamic measures as a surrogate for clinical efficacy. Numerous publications have stressed that the efficacy of IPC devices of any configuration is directly related to compliance of patients and nursing staff in the application
Fig 4. Peak systolic velocity of knee-length and thigh-length intermittent pneumatic compression (IPC) devices. aP ¼ .0019.
of these devices. Thigh-high devices are commonly demonstrated to have a lower satisfaction rating by patients and nursing personnel.15,16 Our results suggest that thighlength devices may offer improved protection against VTE through superior reduction in venous stasis. Education of patients and nursing personnel about these benefits may lead to increased compliance and improved IPC efficacy with a thigh-length device. In addition, development of more comfortable compression sleeves may improve compliance and patient tolerance of thigh-length sleeves.17 Several potential shortcomings of these data exist. First, the study was conducted in healthy individuals. Although patients who receive the device are typically compromised and in a hospital setting, a hemodynamic study by Kakkos et al9 demonstrated a similar hemodynamic response between healthy individuals and those with chronic venous insufficiency, suggesting generalizability of our results. Second, the knee and thigh IPC devices were insonated at different sites. The sites of insonation of the common femoral vein for the thigh-length device and the popliteal vein for the knee-length device were selected to minimize the potential contribution of the capacitance of the thigh deep venous system in diminishing the augmentation of PSV and TVF in the KLS. Because tissue volume under compression appears to be directly correlated with augmentation of hemodynamics with IPC, we felt that insonation closest to the region of compression would provide the most rigorous comparison of the two devices. CONCLUSIONS
Fig 3. Total volume flow of knee-length and thigh-length intermittent pneumatic compression (IPC) devices. aP < .0001.
Using hemodynamic data as a surrogate for clinical effectiveness, this trial suggests that the improved hemodynamic effects of the thigh-length IPC device may provide superior thromboprophylaxis to a knee-length IPC device. The hemodynamic superiority of the thigh-length IPC device compared with the knee-length IPC device, as measured by augmented TVF and PSV, was highly significant in this study. We postulate that the increased volume of compressed tissue accounts for the findings, consistent with a study of foot vs foot and calf compressive devices.18
JOURNAL OF VASCULAR SURGERY: VENOUS AND LYMPHATIC DISORDERS Volume 1, Number 3
The execution of a large prospective, controlled, multicenter clinical trial to confirm the results of this trial would be ideal; however, completion of these evaluations is limited by their considerable resource requirements.
8.
9.
AUTHOR CONTRIBUTIONS Conception and design: RP Analysis and interpretation: RP, PC Data collection: PC Writing the article: RP Critical revision of the article: RP, PC Final approval of the article: RP Statistical analysis: RP Obtained funding: RP, PC Overall responsibility: RP REFERENCES 1. Geerts WH, Bergqvist D, Pineo GF, Heit JA, Samama CM, Lassen MR, et al. Prevention of venous thromboembolism: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008;133(6 Suppl):381-453S. 2. Anderson FA Jr, Wheeler HB. Physician practices in the management of venous thromboembolism: a community-wide survey. J Vasc Surg 1992;16:707-14. 3. Zhan C, Miller MR. Excess length of stay, charges, and mortality attributable to medical injuries during hospitalization. JAMA 2003;290:1868-74. 4. Hospital Quality Alliance (HQA) 2004-2007 measure build-out table. Centers for Medicare & Medicaid Services Web site. Available at: http://www.cms.gov/HospitalQualityInits/downloads/HospitalHQA 2004_2007200512.pdf. Accessed November 11, 2011. 5. Guyatt GH, Akl EA, Crowther M, Gutterman DD, Schünemann HJ. Antithrombotic therapy and prevention of thrombosis: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (9th Edition). Chest 2012;14(Suppl):7-47S. 6. Urbankova J, Quiroz R, Kucher N, Goldhaber SZ. Intermittent pneumatic compression and deep vein thrombosis prevention. A metaanalysis in postoperative patients. Thromb Haemost 2005;94:1181-5. 7. Kakkos SK, Caprini JA, Geroulakos G, Nicolaides AN, Stansby GP, Reddy DJ. Combined intermittent pneumatic leg compression and
10.
11.
12.
13.
14.
15.
16.
17.
18.
Patterson and Cardullo 279
pharmacological prophylaxis for prevention of venous thromboembolism in high-risk patients. Cochrane Database Syst Rev 2008:CD005258. Vanek VW. Meta-analysis of effectiveness of intermittent pneumatic compression devices with a comparison of thigh-high to knee-high sleeves. Am Surg 1998;64:1050-8. Kakkos SK, Szendro G, Griffin M, Sabetai MM, Nicolaides AN. Improved hemodynamic venous effectiveness and associated clinical correlations of a new intermittent pneumatic compression system in patients with chronic venous insufficiency. J Vasc Surg 2001;34: 915-22. Kakkos SK, Griffin M, Geroulakos G, Nicolaides AN. The efficacy of a new portable sequential compression device (SCD Express) in preventing venous stasis. J Vasc Surg 2005;42:296-303. Kakkos S, Szendro G, Griffin M, Daskalopoulou SS, Nicolaides A. The efficacy of the new SCD Response Compression system in the prevention of venous stasis. J Vasc Surg 2000;32:932-40. CLOTS (Clots in Legs Or sTockings after Stroke) Trial Collaboration. Thigh-length versus below-knee stockings for deep venous thrombosis prophylaxis after stroke: a randomized trial. Ann Intern Med 2010;153: 553-62. Loomba RS, Arora RR, Chandrasekar S, Shah PH. Thigh-length versus knee-length compression stockings for deep vein thrombosis prophylaxis in the inpatient setting. Blood Coagul Fibrinolysis 2012;23: 168-71. Sajid MS, Desai M, Morris RW, Hamilton G. Knee length versus thigh length graduated compression stockings for prevention of deep vein thrombosis in postoperative surgical patients. Cochrane Database Syst Rev 2012;(5):CD007162. Hilleren-Listerud AE. Graduated compression stocking and intermittent pneumatic compression device length selection. Clin Nurse Spec 2009;23:21-4. Proctor MC, Greenfield LJ, Wakefield TW, Zajkowski PJ. A clinical comparison of pneumatic compression devices: the basis for selection. J Vasc Surg 2001;34:459-63; discussion: 463-4. Conway D, Quatrara B. DVT prophylaxis with a new compression sleeve following surgery: the role of nurses and the importance of patient compliance. Poster/abstract presentation, NAON May 2011. Delis KT, Slimani G, Hafez HM, Nicolaides AN. 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. Eur J Vasc Endovasc Surg 2000;19:250-60.
Submitted Jul 8, 2012; accepted Sep 22, 2012.