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American Journal of Critical Care. 2006;15: 402-412
Copyright © 2006 by the American Association of Critical-Care Nurses.
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CE Article and Journal Club Feature

Mechanical Thromboprophylaxis in Critically Ill Patients: A Systematic Review and Meta-Analysis

By Anthony Limpus, RN, Wendy Chaboyer, RN, PhD, Ellen McDonald, RN and Lukman Thalib, PhD.. From Princess Alexandra Hospital, Woolloongabba, Queensland, Australia (AL), Griffith University, Gold Coast, Queensland, Australia (WC), McMaster University Medical Centre, Hamilton, Ontario, Canada (EM), and Kuwait University, Safat, Kuwait (LT).


   Abstract
Top
 Abstract
Mechanical Prophylaxis
 Objective
 Methods
 Results
 Discussion
 Summary
 References
 
• 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.

Pulmonary embolus is a potentially life-threatening situation for the critically ill. In critically ill patients, pulmonary embolus, which precipitates hemodynamic instability, is associated with a 30% mortality rate.1 Previous research has shown that deep vein thrombosis (DVT) of the lower limbs is primarily responsible for the vast majority of cases of pulmonary embolus in hospitalized patients.2 Recent studies3,4 have shown that despite prophylaxis, DVT occurs in approximately 11% of intensive care patients. A number of reviews have been undertaken in recent years to examine the development and prevention of DVT in intensive care patients.2,5–7 In addition, a number of guidelines also exist for DVT prophylaxis.8–11


Pulmonary embolus is life threatening in critically ill patients and has a 30% mortality rate.

 

Most of these guidelines, however, are for medical or surgical patients9 and cannot be extrapolated to intensive care patients. As a result, the possibility that the benefit-to-risk ratio for venous thromboembolism in intensive care patients may be different from that in other patients also must be considered.6


   Mechanical Prophylaxis
Top
 Abstract
 Mechanical Prophylaxis
Objective
 Methods
 Results
 Discussion
 Summary
 References
 
Mechanical approaches for the prevention of DVT can be broadly classified as either static or dynamic. Graduated compression stockings (GCS), available in either thigh or knee length, are the only devices represented in the static classification. Although the mechanism of action for GCS is not fully understood, it is generally accepted that the change in the diameter of the vein lumen, as a result of graded circumferential pressure, forms the basis of the protective function.12

Dynamic approaches for prevention of DVT include devices that provide intermittent pneumatic compression of either the foot, the calf, or the calf and thigh. The compression is generated by an external electrical compressor that intermittently inflates a cuff or sleeve applied over one or more of those anatomical areas. These devices are broadly known as pneumatic compression devices or sequential compression devices. Their mechanism of action relies on either graded circumferential or uniform intermittent compression.

The potential benefit of mechanical thromboprophylaxis can be viewed from 2 perspectives. First, mechanical thromboprophylaxis may be useful as an interim or alternative measure until pharmacological prophylaxis can be safely introduced. That is, mechanical approaches can be used in patients in whom pharmacological agents are either contraindicated or in whom the likelihood of "catastrophic" bleeding poses an unacceptable risk.12 Second, mechanical approaches may act in a synergistic manner and as a result provide additional protective benefit when combined with mainstay pharmacological prophylaxis.7 This benefit, however, has yet to be demonstrated empirically in intensive care patients.


   Objective
Top
 Abstract
 Mechanical Prophylaxis
 Objective
Methods
 Results
 Discussion
 Summary
 References
 
The objective of this systematic review was to assess the evidence available on the effect of compression and pneumatic devices on thromboprophylaxis in critically ill patients and to obtain an estimate of the pooled effect on the differences between the use of compression and pneumatic devices versus control interventions. That is, a meta-analysis of similar studies was performed to ascertain the effect of compression and pneumatic devices on DVT.


Mechanical prophylaxis consists of graded compression stockings and pneumatic compression devices.

 


   Methods
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 Abstract
 Mechanical Prophylaxis
 Objective
 Methods
Results
 Discussion
 Summary
 References
 
Two experienced reviewers (WC, AL) systematically searched for potentially relevant articles in The Cochrane Library, PubMed, Agency for Healthcare Research and Quality, The Joanna Briggs Institute, and National Guidelines Clearinghouse databases from 1990 to present. Earlier studies were not considered because clinical practice and DVT prophylaxis including mechanical devices prior to the 1990s most likely differed from more recent practices. Reference lists and bibliographies of published works also were examined. A combination of the following terms was used in the search: "DVT," "venous thromboembolism," "graduated compression stockings" or "elastic compression stockings" or "anti-embolic stockings" or "TED stockings," "sequential compression devices," "pneumatic compression devices," "pneumatic compression boots" or "intermittent pneumatic compression boots," "mechanical prophylaxis," "critical care," and "intensive care."

Studies were included if the study samples consisted of intensive care patients, including trauma, surgical, medical, and coronary patients. Studies were excluded if they indicated that intensive care patients were included but did not provide a breakdown into subgroups of intensive care patients. We had no language restrictions, but we were able to review only the abstracts of non-English publications. Potentially relevant citations were evaluated for inclusion in duplicate by 2 of us (WC, AL).

In duplicate and independently, 2 researchers (WC, EM) abstracted data on the study design, population, intervention, diagnostic tests, and outcomes, assessing the methodological quality of each aspect. This assessment was informed by the Cochrane handbook’s description of assessing study quality by considering the potential influence of selection, performance, detection, and attrition bias.13 These concepts resulted in detailed documentation of (1) the sample including the population, sample size, and response rates (if applicable); (2) the intervention (if applicable); (3) the diagnostic tests used to assess the outcome (if applicable); and (4) the actual outcome measured. When discrepancies arose, the studies were reviewed again and the issues were resolved by consensus.

For the 2 randomized controlled trials (RCTs), a meta-analysis was conducted to obtain the combined risk ratio estimates for the differences in the effects due to intervention and control with compression and pneumatic devices in intensive care patients. Meta-analysis has been defined as "the statistical combination of results from two or more separate studies."14 Data were analyzed as rate data, that is, the incidence of DVT in each group. The pooled risk ratio was estimated by using both fixed and random effects models. Results were summarized in a forest plot, also termed a confidence interval plot. This plot displays estimates of the treatment effects of the individual studies and the estimate from the meta-analysis. Any publication bias among these RCTs was assessed by using a funnel plot. A funnel plot is "a scatterplot of treatment effect against a measure of study size"15 and is used to detect bias schematically. If publication bias is unlikely, then a symmetric inverted funnel shape is displayed, with asymmetry suggesting either publication bias or systematic differences between small and large studies.


   Results
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 Abstract
 Mechanical Prophylaxis
 Objective
 Methods
 Results
Discussion
 Summary
 References
 
A total of 21 studies that included compression and pneumatic devices for thromboprophylaxis were reviewed. These studies were conducted between 1992 and 2005. We found 5 relevant RCTs16–20 and 13 observational studies3,4,21–31 that examined the influence of compression and pneumatic devices on venous thromboembolism in the critical care population. Three surveys of current clinical practices also were identified.32–34 The total number of participants in RCTs and observational studies was 4232, with sample sizes ranging from 20 to 1222.

Randomized Controlled Trials
Five RCTs16–20 were found that included mechanical methods of DVT prophylaxis in intensive care patients (Table 1Go). A total of 811 patients were involved in all 5 trials (range 20–442). Patients in the trials included trauma patients17–20 and myocardial infarction patients aged more than 70 years.16 Blinded outcome assessment was used in only 1 of the 5 studies.19


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  		Table 1 Randomized controlled trials evaluating compression and pneumatic devices in intensive care patients

 
The methods of prophylaxis compared differed in 4 of the 5 trials. These comparisons included intermittent pneumatic compression versus low-molecular-weight heparin,19,20 GCS versus no GCS,16 pneumatic compression devices versus foot pump,17 and the evaluation of 2 different devices providing intermittent pneumatic compression.18

Of the 5 RCTs, only 2 qualified for the meta-analysis because of their comparable samples (trauma patients), treatment comparisons (ie, compression and pneumatic devices vs low-molecular-weight heparin), and outcomes (incidence of vascular thromboembolism). In the 3 excluded RCTs, Elliott et al17 compared 2 compression and pneumatic devices, Murakami et al18 examined the compliance between 2 compression and pneumatic devices, and Kierkegaard and Norgren16 compared GCS with no GCS in older patients with myocardial infarction.

Meta-analysis results revealed that the point estimate of the risk ratio obtained from the random effects model was 2.37, indicative of favoring the control over the intervention for the DVT outcome (Table 2Go). However, the 95% CI of 0.57 to 9.90 indicated no significant differences between the intervention and the control. The fixed model also yielded consistently similar estimates of 2.56 (95% CI 0.78–8.37) as shown in the forest plot (see FigureGo). The funnel plot was symmetrical, and because both the meta-analysis and 1 of the 2 studies in it favored the control it is unlikely that publication bias exists in this research.


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  		Table 2 Results of the meta-analysis

 

Figure 1
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  		Forest plot of risk ratio

 
Observational Studies
A total of 13 observational studies were found (Table 3Go). Of these, 12 (92.3%) were conducted in North America3,4,21–30 (9 in the United States, 3 in Canada), and 1 was a multisite, international study conducted in Canada and France.31 All studies were prospective. The total number of intensive care patients in all 13 studies was 3324 (range 44–1222).


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  		Table 3 Observational studies reporting compression and pneumatic

 
A total of 1474 (44.3%) were medical patients,23,24,31 958 (28.8%) were trauma patients,4,22,28 665 (20%) were medical-surgical patients,3,25,27,29 and 227 (6.8%) were surgical patients.21,30 Each study reported patients receiving different types of prophylaxis, all of which included some form of pneumatic or compression devices.

Seven studies3,4,22,24,25,28,29 included either incidence or prevalence of DVT as a measure, which represented a total of 1775 patients. Incidence of DVT in intensive care patients ranged from 11%22 to 56%24 if no treatment was used, 7.4%25 to 40%24 when pharmacological prophylaxis was used, and 0%22 to 33%24 when mechanical prophylaxis was used. Two studies had incidences of 13%28 and 31%29 for combination of pharmacological and mechanical prophylaxis. In 4 studies,23,27,30,31 the use of mechanical devices and drugs for DVT prophylaxis was documented. In another 4 studies24,25,28,29 with a total of 495 patients, mechanical prophylaxis was compared with pharmacological prophylaxis in relation to either the incidence or prevalence of DVT.

In the 3 studies25,28,29 in which the researchers undertook further analysis, no significant difference was found between the 2 forms of treatment for reducing the incidence of DVT. However, because of their small samples, the power of these studies must be questioned, because the true efficacy of pharmacological and mechanical prophylaxis may not have been recognized. In the reports of 2 studies,21,26 the authors also described the correct application and maintenance of mechanical devices.

Because observational studies are not designed to evaluate effectiveness,35 conclusions about the use of pneumatic and compression devices cannot be drawn. Direct observation of venous thromboembolism was reported in 7 studies3,4,22–25,28; however, a range of methodological issues, including the potential for bias and confounding, make meaningful interpretation difficult and problematic.

Surveys
We found 3 surveys32–34 in which researchers queried clinicians about the use of mechanical measures for thromboprophylaxis in the context of current clinical practices (Table 4Go). In total, 445 clinicians were surveyed in these 3 studies, representing 290 intensive care units in Canada, Australia, and Germany. Cook et al32 found that 17 (58.6%) of the 29 Canadian medical directors surveyed incorporated GCS as part of routine DVT prophylaxis for the 3 risk categories (recent bleeding, active bleeding, and high risk of bleeding). Pneumatic compression devices were used less frequently; 12 medical directors (41.4%) reported the use of these devices in patients with a recent history of bleeding.


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  		Table 4 Survey data

 
The findings of Limpus and Chaboyer34 showed that GCS were used in conjunction with anticoagulants in 88 (97%) of the 91 Australian units that responded and with sequential compression devices in 48 units (53%). Knee-length stockings were used most frequently (n = 37, 41%); however, 31 units (34%) used both knee- and thigh-length stockings. Mullges et al33 surveyed nurses in 324 nonsurgical German intensive care units and found that GCS were provided to all patients as part of routine prophylaxis in 8 (5.6%) of the 144 units that responded. GCS were not used in 18 units (12.5%).

These studies suggest that practices vary widely within countries and throughout the world. Most likely the lack of definitive evidence is a significant contributing factor to these variations in clinical practice.


   Discussion
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 Abstract
 Mechanical Prophylaxis
 Objective
 Methods
 Results
 Discussion
Summary
 References
 
Venous thromboembolism and its prevention in intensive care units has attracted considerable attention by way of numerous review papers, systematic reviews,5,6,9 and a meta-analysis.2 Morris and Woodcock35 recently summarized the venous flow effects of compression devices in relation to DVT prophylaxis. Three Cochrane Library reviews36–38 addressing mechanical prophylaxis also have been undertaken; however, none of these reviews focuses on the intensive care population. We also found an international consensus statement39 providing guidelines for the prevention of venous thromboembolism and a practice alert11 on DVT prophylaxis from the American Association of Critical-Care Nurses. We found no meta-analyses that focused purely on nonpharmacological prophylaxis in intensive care patients.

A systematic review39 of all relevant RCTs included evidence supporting the effectiveness of intermittent pneumatic compression, GCS, and GCS in combination with low-dose heparin in moderate risk, general surgical patients. No equivalent evidence to guide practice in high-risk critical care patients was found.

Little evidence is available on the mechanical methods of DVT prophylaxis in critically ill patients. Not only have few trials been done, but the overall numbers of patients in the trials are extremely small. Thus, few RCTs are available to provide guidance for practice. In contrast, a large number of observational studies indicate that compression and pneumatic devices are used widely in practice.


Although a large number of studies indicate that mechanical devices are widely used, few clinical trials are available to provide guidance for practice.

 

The observational study data are predominantly from North America, where the use of unfractionated heparin is the DVT prophylaxis of choice. In Europe, unlike North America, low-molecular-weight heparin is used predominantly. An Australian survey indicates that mechanical approaches to DVT prevention are common there.34 The observational data suggest that use of mechanical strategies for DVT prevention is widespread. The overall approach, however, is rather ad hoc or based on tradition because no guidelines based on evidence exist. Although 28.8% of the patients in the observational trials were trauma patients who did not receive anticoagulants, these data are no longer helpful in interpreting the results because strong data that support the use of low-molecular-weight heparin in this population are now available.40–42

Surveys of stated practice helped inform our systematic review, in that these studies provide useful indicators of current practices as perceived by those responding to the surveys. Three prospective multicenter surveys met our inclusion criteria: 1 study each from Australia,34 Canada,32 and Germany.33 These survey data represent opinions of 264 clinicians (29 physicians and 235 nurses). These survey results suggest that clinical practice varies widely, both within and between countries.


Graded compression stockings are used inappropriately, and their application is variable.

 

Our review suggests that GCS are not properly used to prevent venous thromboembolism. In addition to improper use of GCS, the frequency of use of GCS is also variable. It is therefore not unreasonable to assume that similar deficiencies may exist with other mechanical devices. Perhaps these deficiencies associated with mechanical strategies relate to a lack of empirical evidence. This lack of empirical evidence means that no guidelines have been clearly accepted, and thus practice varies widely.

The aim of future trials should be to determine what additional protective benefit compression and pneumatic devices provide when combined with mainstay pharmacological prophylaxis. Because this added benefit may be small, large-scale multisite trials will most likely be required. In designing these trials, researchers should recognize that clinical factors such as incorrect application or unplanned removal of devices may affect the study results. Another important consideration for future researchers is the type of tests used to diagnose DVT and their frequency of use; future comparisons would be more relevant if similar diagnostic criteria and measurements could be used.

The methods used in the upcoming PROphylaxis for ThromboEmbolism in Critical Care Trial (PROTECT)42 may provide a basis and guidance for researchers designing future studies of mechanical thromboprophylaxis.


   Summary
Top
 Abstract
 Mechanical Prophylaxis
 Objective
 Methods
 Results
 Discussion
 Summary
References
 
Our findings highlight the lack of appropriately designed RCTs to guide the use of compression and pneumatic devices as a legitimate strategy for DVT prophylaxis in critical care patients. Even though research in this area poses some unique challenges for researchers, little or no evidence is available to guide clinicians. Best practice in DVT prophylaxis for critically ill patients will remain based on recommendations5 until definitive risk-to-benefit ratios are available either to justify the incorporation of mechanical prophylaxis or to support the sole use of pharmacological measures. Until such time, questions about the role of mechanical thromboprophylaxis in critically ill patients remain unanswered.

To purchase electronic or print reprints, contact The InnoVision Group, 101 Columbia, Aliso Viejo, CA 92656. Phone, (800) 809-2273 or (949) 362-2050 (ext 532); fax, (949) 362-2049; e-mail, reprints{at}aacn.org.


   REFERENCES
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 Abstract
 Mechanical Prophylaxis
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 Methods
 Results
 Discussion
 Summary
 References
 

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  15. Higgins JPT, Green S, eds. Considerations and recommendations for figures in Cochrane reviews: graphs of statistical data. In: Higgins JPT, Green S, eds. Cochrane Handbook for Systematic Reviews of Interventions. Version 4.2.5 [updated May 2005]. Chichester, England: John Wiley & Sons Ltd; Appendix 8a:215–229. Also available at: http://www.cochrane.org/resources/handbook/hbook.htm. Accessed April 24, 2006.
  16. Kierkegaard A, Norgren L. Graduated compression stockings in the prevention of deep vein thrombosis in patients with acute myocardial infarction. Eur Heart J. 1993;14:1365–1368.[Abstract/Free Full Text]
  17. Elliott CG, Dundney TM, Egger M, et al. Calf-thigh sequential compression compared with plantar venous pneumatic compression to prevent DVT after non-lower extremity trauma. J Trauma. 1999;47:25–32.[Medline]
  18. Murakami M, McDill TL, Cindrick-Pounds C, et al. Deep vein thrombosis prophylaxis in trauma: improved compliance with a novel miniaturized pneumatic compression device. J Vasc Surg. 2003;38:923–927.[Medline]
  19. Ginzburg E, Cohn SM, Lopez J, et al. Randomized clinical trial of intermittent pneumatic compression and low molecular weight heparin in trauma. Br J Surg. 2003;90:1338–1344.[Medline]
  20. Kurtoglu M, Yanar H, Bilsel Y, et al. Venous thromboembolism prophylaxis after head and spinal trauma: intermittent pneumatic compression devices versus low molecular weight heparin. World J Surg. 2004;28:807–811.[Medline]
  21. Comerota AJ, Katz ML, White JV. Why does prophylaxis with external pneumatic compression for deep vein thrombosis fail? Am J Surg. 1992; 164:265–268.[Medline]
  22. Gersin K, Grindlinger GA, Lee V, Dennis RC, Wedel SK, Cachecho R. The efficacy of sequential compression devices in multiple trauma patients with severe head injury. J Trauma. 1994;37:205–208.[Medline]
  23. Keane M, Ingenito E, Goldhaber S. Utilization of venous thromboembolism prophylaxis in the medical intensive care unit. Chest. 1994;106:13–14.[Abstract/Free Full Text]
  24. Hirsch DR, Ingenito EP, Goldhaber SZ. Prevalence of deep venous thrombosis among patients in medical intensive care. JAMA. 1995;274:335–337.[Abstract/Free Full Text]
  25. Marik PE, Andrews L, Maini B. The incidence of deep venous thrombosis in ICU patients. Chest. 1997;111:661–664.[Abstract/Free Full Text]
  26. Anglen JO, Goss K, Edwards J, Huckfeldt RE. Foot pump prophylaxis for deep venous thrombosis: the rate of effective usage in trauma patients. Am J Orthop. 1998;27:580–582.[Medline]
  27. Ryskamp RP, Trottier SJ. Utilization of venous thromboembolism prophylaxis in a medical-surgical ICU. Chest. 1998;113:162–164.[Abstract/Free Full Text]
  28. Velmahos GC, Nigro J, Tatevossian R, et al. Inability of an aggressive policy of thromboprophylaxis to prevent deep venous thrombosis (DVT) in critically injured patients: are current methods of DVT prophylaxis insufficient? J Am Coll Surg. 1998;187:529–533.[Medline]
  29. Cook D, Attia J, Weaver B, McDonald E, Meade M, Crowther M. Venous thromboembolic disease: an observational study in medical-surgical intensive care unit patients. J Crit Care. 2000;15:127–132.[Medline]
  30. Cook D, Lapoeta D, Skrobik Y, et al. Prevention of venous thromboembolism in critically ill surgery patients: a cross-sectional study. J Crit Care. 2001;16:161–166.[Medline]
  31. Lacherade JC, Cook D, Heyland D, Chrusch C, Brochard L, Brun-Buisson C. Prevention of venous thromboembolism in critically ill medical patients: a Franco-Canadian cross-sectional study. J Crit Care. 2003;18:228–237.[Medline]
  32. Cook D, McMullin J, Hodder R, et al. Prevention and diagnosis of venous thromboembolism in critically ill patients: a Canadian survey. Crit Care. 2001;5:336–342.[Medline]
  33. Mullges W, Steinke E, Moldenhauer G, Berens N. Customary use of compression stockings for prevention of thrombosis in medical intensive care units in Germany [in German]. Dtsch Med Wochenschr. 2001;126:867–871.[Medline]
  34. Limpus A, Chaboyer W. The use of graduated compression stockings in Australian intensive care units: a national audit. Aust Crit Care. 2003;16:53–58.
  35. Morris RJ, Woodcock JP. Evidence-based compression: prevention of stasis and deep vein thrombosis. Ann Surg. 2004;239:162–171.[Medline]
  36. Amaragiri SV, Lees TA. Elastic compression stockings for prevention of deep vein thrombosis. Cochrane Database Syst Rev. Issue 3, 2000:CD001484.
  37. Kolbach DN, Sandbrink MWC, Hamulyak K, Neumann HAM, Prins MH. Non-pharmaceutical measures for prevention of post-thrombotic syndrome. Cochrane Database Syst Rev. Issue 3, 2003:CD004174.
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  40. Geerts WH, Jay RM, Code KI, et al. A comparison of low-dose heparin with low-molecular-weight heparin as prophylaxis against venous thromboembolism after major trauma. N Engl J Med. 1996;335:701–707.[Abstract/Free Full Text]
  41. Knudson MM, Morabito D, Paiement GD, Shackleford S. Low molecular weight heparin in preventing thromboembolism in trauma patients. J Trauma. 2001;41:446–459.
  42. US National Institutes of Health. PROphylaxis for ThromboEmbolism in Critical Care Trial (PROTECT). Available at: http://www.clinicaltrials.gov/ct/show/NCT00182143. Accessed April 24, 2006.
 

Journal Club Article Discussion Points

In a journal club, research articles are reviewed and critiqued. General and specific questions help to aid journal club participants in probing the quality of the research study, the appropriateness of the study design and methods, the validity of the conclusions, and the implications for practice.

When critically appraising this issue’s AJCC journal club article, "Mechanical Thromboprophylaxis in Critically Ill Patients: A Systematic Review and Meta-Analysis," consider the questions and discussion points listed below.

Study Synopsis: Compression and pneumatic devices are commonly used in the intensive care unit (ICU) to prevent thromboemboli in critically ill patients. This article reports on the results of a systematic review of randomized clinical trials evaluating the effect of compression and pneumatic devices on thromboprophylaxis in critically ill patients. Twenty-one studies identified in the literature, including 5 randomized clinical trials, were evaluated for their impact on reducing the incidence of venous thromboembolism in ICU patients. A meta-analysis of the 5 randomized clinical trials that included 811 patients revealed no significant differences between intervention and controls. The results of the meta-analysis indicate that limited evidence exists to suggest that compression and pneumatic devices are significantly different from no treatment or use of low-molecular-weight heparin.

  1. Description of the Meta-Analysis
  2. Literature Evaluation
  3. Sample
  4. Methods and Design
  5. Results
  6. Clinical Significance

Information From the Authors: Anthony Limpus, RN, lead author of this journal club article, provided additional information about the study. Limpus explains that the team decided to conduct the meta-analysis to critically evaluate the effect of a relatively common ICU practice as well as to extend the research evidence. He relates: "The background is that the meta-analysis is part of a program of research that aims to provide the evidence as to the ‘ideal’ length of graduated compression stocking for use in the critically ill. We did not plan to conduct the meta-analysis when we first started, but as the program matured it became apparent that it would be a good idea to undertake, as it would support our credentials to attract funding for larger studies in the area of mechanical thromboprophylaxis."

Limpus shares that the team has conducted several previous studies related to thromboprophylaxis, including a national audit on the use of graduated compression stockings in Australian ICUs, the effect of body position and graduated compression stocking length on blood flow velocity in the femoral vein, and compression profiles of graduated compression stockings following repetitive use by patients and hospital laundering, among other studies.

Limpus also shares that the most surprising finding of the meta-analysis was the lack of effect: "Obviously the finding from the 2 [randomized clinical trials] that there were no significant differences between the intervention and control stands out. However, the striking thing for me was that nobody has yet come to terms with the issues (difficulties) related to designing appropriate studies investigating pneumatic and compression devices. I think there needs to be a change in the mindset of researchers to possibly view these devices much the same as drugs. By that I mean to demonstrate efficacy we need to somehow quantify the patient’s exposure or dose of mechanical thromboprophylaxis."

Implications for Practice: According to the meta-analysis, the effect of the use of compression and pneumatic devices on thromboprophylaxis remains uncertain. Limpus suggests that "the major implication for the readership is to increase the awareness of the importance of compression and pneumatic devices. As nurses we have a responsibility to ensure that the appropriate devices are selected, correctly sized, and applied and then maintained."

"Hopefully," Limpus concludes, "this meta-analysis might act as a catalyst for further inquiry to either demonstrate efficacy in the critical care population, stimulate ongoing debate to question their use, and/or reduce the factors that limit their performance (appropriate selection, correct sizing and application). Either way, this meta-analysis has highlighted that study of compression and pneumatic devices is a huge area of opportunity for nurse researchers."

Journal Club feature commentary is provided by Ruth Kleinpell.




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