Deep venous thrombosis in medical-surgical critically ill patients: prevalence, incidence, and risk factors

OBJECTIVE

Critically ill patients may be at high risk of venous thromboembolism. The objective was to determine the prevalence, incidence, and risk factors for proximal lower extremity deep venous thrombosis among critically ill medical-surgical patients.

DESIGN

Prospective cohort.

SETTING

Closed university-affiliated intensive care unit.

PATIENTS

We enrolled consecutive patients > or =18 yrs of age expected to be in intensive care unit for > or =72 hrs. Exclusion criteria were an admitting diagnosis of trauma, orthopedic surgery, pregnancy, and life support withdrawal.

INTERVENTIONS

Interventions included bilateral lower extremity compression ultrasound within 48 hrs of intensive care unit admission, twice weekly, and if venous thromboembolism was clinically suspected. Thromboprophylaxis was protocol directed and universal. We recorded deep venous thrombosis risk factors at baseline and daily, using multivariate regression analysis to determine independent predictors. Patients were followed to hospital discharge.

RESULTS

Among 261 patients with a mean Acute Physiology and Chronic Health Evaluation II score of 25.5 (+/-8.4), the prevalence of deep venous thrombosis was 2.7% (95% confidence interval 1.1-5.5) on intensive care unit admission, and the incidence was 9.6% (95% confidence interval 6.3-13.8) over the intensive care unit stay. We identified four independent risk factors for intensive care unit-acquired deep venous thrombosis: personal or family history of venous thromboembolism (hazard ratio 4.0, 95% confidence interval 1.5-10.3), end-stage renal failure (hazard ratio 3.7, 95% confidence interval 1.2-11.1), platelet transfusion (hazard ratio 3.2, 95% confidence interval 1.2-8.4), and vasopressor use (hazard ratio 2.8, 95% confidence interval 1.1-7.2). Patients with deep venous thrombosis had a longer duration of mechanical ventilation (p = .03), intensive care unit stay (p = .005), and hospitalization (p < .001) than patients without deep venous thrombosis.

CONCLUSIONS

Despite universal thromboprophylaxis, medical-surgical critically ill patients remain at risk for lower extremity deep venous thrombosis. Further research is needed to evaluate the risks and benefits of more intense venous thromboembolism prophylaxis.

Limits on gravitational-wave emission from selected pulsars using LIGO data

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars.

Patients with severe sepsis vary markedly in their ability to generate activated protein C

Activated protein C (APC) supplementation significantly reduces mortality in patients with severe sepsis, presumably by down-regulating coagulation, inflammation, and apoptosis. In vivo, endogenous APC is generated from protein C (PC) “on demand” in response to elevated thrombin levels. Thrombomodulin and endothelial cell protein C receptor are endothelial receptors required to generate APC endogenously. Since these receptors may be down-regulated in sepsis, we measured plasma markers of APC generation in 32 patients with severe sepsis to determine whether APC generation is impaired and whether markers of APC generation correlate with 28-day mortality. Relative to normals, all patients had elevated F1 + 2 and thrombin-antithrombin complex (TAT) levels (markers of thrombin generation and inhibition, respectively), and 28 of 32 patients had reduced PC levels. In 20 patients, APC levels paralleled elevated F1 + 2 levels, whereas 12 patients had low APC levels despite elevated F1 + 2 levels, suggesting that APC generation is impaired in the latter. No significant differences exist between survivors and nonsurvivors with respect to baseline PC levels, F1 + 2 levels, and APACHE II (acute physiology and chronic health evaluation) scores. Baseline APC levels were higher in survivors (P = .024), and baseline F1 + 2/APC ratios were lower in survivors (P = .047). Larger studies are warranted to establish whether APC generation profiles aid in managing sepsis. (Blood. 2004;104:3958-3964)

CD8+ T-cell-depleted, matched unrelated donor, allogeneic bone marrow transplantation for advanced AML using busulfan-based preparative regimens

The role of T-cell depletion (TCD) to prevent graft-versus-host disease (GVHD) after matched unrelated donor allogeneic bone marrow transplant (MUD BMT) remains undefined. Most studies employ total body irradiation and pan TCD. Between March 1993 and June 2002, we treated 33 relapsed acute myelogenous leukemia (AML) patients with busulfan-based preparative regimens and selective TCD. The preparative regimen consisted of busulfan 14 mg/kg, cyclophosphamide 120 mg/kg and VP-16 50 mg/kg in all but one patient who only received busulfan and cyclophosphamide. Donor marrow was depleted of CD8+ T cells by immunomagnetic bead separation. The patients were also treated with cyclosporine and methylprednisolone or FK-506 and mini-dose methotrexate. Four (15%) of 33 patients developed graft failure or rejection. However, three of these patients were serologically mismatched at HLA-Cw. Although 67% of evaluable patients developed acute GVHD, severe grade III-IV acute GVHD only developed in 19%. The severity of acute GVHD correlated with the degree of CD8+ TCD. Median relapse-free survival was 5 months among 20 patients treated with active AML, and 28 months among 13 patients treated in complete remission. Our results confirm that MUD BMT with CD8+ TCD for AML is a potentially curative treatment option.

Applying the Grades of Recommendation for Antithrombotic and Thrombolytic Therapy

This article about the grades of recommendation for antithrombotic and thrombolytic therapy is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Clinicians need to know whether a recommendation is strong or weak, and about the methodological quality of the evidence underlying that recommendation. We determine the strength of a recommendation by considering the trade-off between the benefits of a treatment, on the one hand, and the risks, burdens, and costs on the other. Here, as elsewhere, we assume that a recommended treatment will increase costs (we recognize this is not always the case, but for simplicity we will continue to make this assumption). If the benefits outweigh the risks, burdens, and costs, we recommend that clinicians offer a treatment to typical patients. The uncertainty associated with the trade-off between the benefits and the risks, burdens, and costs will determine the strength of the recommendations. If we are very certain that the benefits do, or do not, outweigh the risks, burdens, and costs, we make a strong recommendation (in our formulation, Grade 1). If we are less certain of the magnitude of the benefits and the risks, burdens, and costs, and thus of their relative impact, we make a weaker Grade 2 recommendation. We grade the methodological quality of a recommendation according to the following criteria. Randomized clinical trials (RCTs) with consistent results provide evidence with a low likelihood of bias, which we classify as Grade A recommendations. RCTs with inconsistent results, or with major methodological weaknesses, warrant Grade B recommendations. Grade C recommendations come from observational studies or from a generalization from one group of patients included in randomized trials to a different, but somewhat similar, group of patients who did not participate in those trials. When we find the generalization from RCTs to be secure, or the data from observational studies overwhelmingly compelling, we choose a Grade C+. When that is not the case, we designate methodological quality as Grade C.

Antithrombotic and Thrombolytic Therapy: From Evidence to Application

This chapter about implementation strategies for practice guidelines is part of the 7th ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that feasibility, acceptability and cost related to implementation strategies may lead to different choices depending on the practice setting (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). To encourage uptake of guidelines to reduce thrombosis, we recommend that appreciable resources be devoted to distribution of educational material (Grade 2B). We suggest that few resources be devoted to educational meetings (Grade 2B), to audit and feedback (Grade 2B), or to educational outreach visits (Grade 2B) to encourage uptake of the guidelines. We suggest that appreciable resources be devoted to computer reminders (Grade 2A) and to patient-mediated interventions (Grade 2B) to encourage uptake of the guidelines. This review suggests that there are few implementation strategies that are of unequivocal, consistent benefit, and that are clearly and consistently worth resource investment. Fully informed decisions will require additional research to identify effective guideline implementation strategies to optimize antithrombotic and thrombolytic therapy.

Methodology for Guideline Development for the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy

This article describes the methodology for the Seventh American College of Chest Physicians (ACCP) Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Guideline authors began by specifying the population, the intervention and alternative, and the outcomes for each clinical question, and defined the criteria for eligible articles, including methodological criteria, for each recommendation. Librarians, in collaboration with guideline authors and methodologists, conducted systematic searches for evidence. Guideline authors systematically evaluated the evidence, considered the full range of benefits, risks, inconvenience, and costs associated with alternative management strategies, considered patients' underlying values and preferences, and made recommendations accordingly. To increase the likelihood that the recommendations adequately represent patient values and preferences, the development process included a review of recommendations by research methodologists, practicing generalists, and specialists. Chapters are organized so that evidence is clearly linked to the relevant recommendations, and that recommendations particularly sensitive to underlying values and preferences are explicitly identified. Authors paid careful attention to the strength of the underlying evidence and to the balance between risks and benefits, which are both reflected in the grades of recommendations. Thus, improvements to the process of making recommendations for the ACCP guidelines include the explicit definition of questions, transparent eligibility criteria for including studies, and the specification of values and preferences underlying recommendations where they are particularly relevant. In combination with our previous practice of grading recommendations according to their strength, and the methodological quality of the supporting studies, these innovations establish our guidelines as, by and large, evidence based.

Evidence-based clinical practice guideline for the prevention of ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) is an important patient safety issue in critically ill patients.

PURPOSE

To develop an evidence-based guideline for the prevention of VAP.

DATA SOURCES

MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews.

STUDY SELECTION

The authors systematically searched for relevant randomized, controlled trials and systematic reviews that involved mechanically ventilated adults and were published before 1 April 2003.

DATA EXTRACTION

Physical, positional, and pharmacologic interventions that may influence the development of VAP were considered. Independently and in duplicate, the authors scored the validity of trials; the effect size and confidence intervals; the homogeneity of results; and safety, feasibility, and economic issues.

DATA SYNTHESIS

Recommended: The orotracheal route of intubation, changes of ventilator circuits only for each new patient and if the circuits are soiled, use of closed endotracheal suction systems that are changed for each new patient and as clinically indicated, heat and moisture exchangers in the absence of contraindications, weekly changes of heat and moisture exchangers, and semi-recumbent positioning in the absence of contraindications. Consider subglottic secretion drainage and kinetic beds. Not recommended: Sucralfate to prevent VAP in patients at high risk for gastrointestinal bleeding and topical antibiotics to prevent VAP. Because of insufficient or conflicting evidence, no recommendations were made about systematically searching for maxillary sinusitis, chest physiotherapy, the timing of tracheostomy, prone positioning, prophylactic intravenous antibiotics, or intravenous plus topical antibiotics.

LIMITATIONS

No formal economic analysis was performed, and patient perspectives were not considered.

CONCLUSION

If effectively implemented, this guideline may decrease the morbidity, mortality, and costs of VAP in mechanically ventilated patients.

Clinician discomfort with life support plans for mechanically ventilated patients

OBJECTIVE

To examine the incidence and predictors of clinician discomfort with life support plans for ICU patients.

DESIGN AND SETTING

Prospective cohort in 13 medical-surgical ICUs in four countries.

PATIENTS

657 mechanically ventilated adults expected to stay in ICU at least 72 h.

MEASUREMENTS AND RESULTS

Daily we documented the life support plan for mechanical ventilation, inotropes and dialysis, and clinician comfort with these plans. If uncomfortable, clinicians stated whether the plan was too technologically intense (the provision of too many life support modalities or the provision of any modality for too long) or not intense enough, and why. At least one clinician was uncomfortable at least once for 283 (43.1%) patients, primarily because plans were too technologically intense rather than not intense enough (93.9% vs. 6.1%). Predictors of discomfort because plans were too intense were: patient age, medical admission, APACHE II score, poor prior functional status, organ dysfunction, dialysis in ICU, plan to withhold dialysis, plan to withhold mechanical ventilation, first week in the ICU, clinician, and city.

CONCLUSIONS

Clinician discomfort with life support perceived as too technologically intense is common, experienced mostly by nurses, variable across centers, and is more likely for older, severely ill medical patients, those with acute renal failure, and patients lacking plans to forgo reintubation and ventilation. Acknowledging the sources of discomfort could improve communication and decision making.

Clinically important deep vein thrombosis in the intensive care unit: a survey of intensivists

INTRODUCTION

Outside the intensive care unit (ICU), clinically important deep vein thrombosis (DVT) is usually defined as a symptomatic event that leads to objective radiologic confirmation and subsequent treatment. The objective of the present survey is to identify the patient factors and radiologic features of lower limb DVT that intensivists consider more or less likely to make a DVT clinically important in ICU patients.

METHODS

Our definition of clinically important DVT was a DVT likely to result in short-term or long-term morbidity or mortality if left untreated, as opposed to a DVT that is unlikely to have important consequences. We asked respondents to indicate the likelihood that patient factors and ultrasonographic features make a DVT clinically important using a five-point scale (from 1 = much less likely to 5 = much more likely).

RESULTS

Of the 71 Canadian intensivists who responded, 70 (99%) rated three patient factors as most likely to make a DVT clinically important: clinical suspicion of pulmonary embolism (mean score 4.6), acute or chronic cardiopulmonary morbidity that might limit a patient's ability to tolerate pulmonary embolism (score 4.5), and leg symptoms (score 4.2). Of the ultrasound features, proximal (score 4.7), large (score 4.2), and totally occlusive (score 3.9) thrombi were considered the three most important.

CONCLUSION

When labeling a DVT as clinically important, intensivists rely on different patient specific factors and thrombus characteristics than are used to assess the clinical importance of DVT outside the ICU. The clinical importance of DVT is influenced by unique factors such as cardiopulmonary reserve among mechanically ventilated patients.

Clinician predictions of intensive care unit mortality*

OBJECTIVE

Predicting outcomes for critically ill patients is an important aspect of discussions with families in the intensive care unit. Our objective was to evaluate clinical intensive care unit survival predictions and their consequences for mechanically ventilated patients.

DESIGN

Prospective cohort study.

SETTING

Fifteen tertiary care centers.

PATIENTS

Consecutive mechanically ventilated patients > or = 18 yrs of age with expected intensive care unit stay > or = 72 hrs.

INTERVENTIONS

We recorded baseline characteristics at intensive care unit admission. Daily we measured multiple organ dysfunction score (MODS), use of advanced life support, patient preferences for life support, and intensivist and bedside intensive care unit nurse estimated probability of intensive care unit survival.

MEASUREMENTS AND MAIN RESULTS

The 851 patients were aged 61.2 (+/- 17.6, mean + SD) yrs with an Acute Physiology and Chronic Health Evaluation (APACHE) II score of 21.7 (+/- 8.6). Three hundred and four patients (35.7%) died in the intensive care unit, and 341 (40.1%) were assessed by a physician at least once to have a < 10% intensive care unit survival probability. Independent predictors of intensive care unit mortality were baseline APACHE II score (hazard ratio, 1.16; 95% confidence interval, 1.08-1.24, for a 5-point increase) and daily factors such as MODS (hazard ratio, 2.50; 95% confidence interval, 2.06-3.04, for a 5-point increase), use of inotropes or vasopressors (hazard ratio, 2.14; 95% confidence interval, 1.66-2.77), dialysis (hazard ratio, 0.51; 95% confidence interval, 0.35-0.75), patient preference to limit life support (hazard ratio, 10.22; 95% confidence interval, 7.38-14.16), and physician but not nurse prediction of < 10% survival. The impact of physician estimates of < 10% intensive care unit survival was greater for patients without vs. those with preferences to limit life support (p < .001) and for patients with less vs. more severe organ dysfunction (p < .001). Mechanical ventilation, inotropes or vasopressors, and dialysis were withdrawn more often when physicians predicted < 10% probability of intensive care unit survival (all ps < .001).

CONCLUSIONS

Physician estimates of intensive care unit survival < 10% are associated with subsequent life support limitation and more powerfully predict intensive care unit mortality than illness severity, evolving or resolving organ dysfunction, and use of inotropes or vasopressors.