Michael C. Plewa

BackgroundThe National Quality Forum (NQF) has endorsed a performance measure designed to increase imaging efficiency for the evaluation of pulmonary embolism (PE) in the emergency department (ED). To our knowledge, no published data have examined the effect of patient-level predictors on performance.MethodsTo quantify the prevalence of avoidable imaging in ED patients with suspected PE, we performed a prospective, multicenter observational study of ED patients evaluated for PE from 2004 through 2007 at 11 US EDs. Adult patients tested for PE were enrolled, with data collected in a standardized instrument. The primary outcome was the proportion of imaging that was potentially avoidable according to the NQF measure. Avoidable imaging was defined as imaging in a patient with low pretest probability for PE, who either did not have a D-dimer test ordered or who had a negative D-dimer test result. We performed subanalyses testing alternative pretest probability cutoffs and imaging definitions on measure performance as well as a secondary analysis to identify factors associated with inappropriate imaging. χ² Test was used for bivariate analysis of categorical variables and multivariable logistic regression for the secondary analysis.ResultsWe enrolled 5940 patients, of whom 4113 (69%) had low pretest probability of PE. Imaging was performed in 2238 low-risk patients (38%), of whom 811 had no D-dimer testing, and 394 had negative D-dimer test results. Imaging was avoidable, according to the NQF measure, in 1205 patients (32%; 95% CI, 31%-34%). Avoidable imaging owing to not ordering a D-dimer test was associated with age (odds ratio [OR], 1.15 per decade; 95% CI, 1.10-1.21). Avoidable imaging owing to imaging after a negative D-dimer test result was associated with inactive malignant disease (OR, 1.66; 95% CI, 1.11-2.49).ConclusionsOne-third of imaging performed for suspected PE may be categorized as avoidable. Improving adherence to established diagnostic protocols is likely to result in significantly fewer patients receiving unnecessary irradiation and substantial savings.

The purpose of the present study was to demonstrate the contribution of pulmonary-generated reactive oxygen species (ROS) on cardiac dysfunction using a rat model of ischemia–reperfusion (IR) injury. Three groups of rats were subjected to regional IR injury in (i) lung, (ii) heart, (iii) lung + heart. A fourth (control) group of rats were instrumented using the same methods but without induction IR. Hemodynamic data were recorded in real time. Blood from the proximal aorta was sampled during baseline, ischemia, and reperfusion, mixed with α-phenyl-N-tert-butylnitrone (PBN) for measuring ROS by electron paramagnetic resonance spectrometry. Data were analyzed by a two-way analysis of variance. The results showed that the lung IR generated an increased burst of ROS that resulted in significant cardiac dysfunction, including hypotension and ECG changes. The results indicated that generation of ROS as a result of acute IR lung injury may be sufficiently large enough to cause direct cardiac dysfunction that is independent of injury caused to the myocardium as a result of regional myocardial IR injury alone.

Objectives:  Available D‐dimer assays have low specificity and may increase radiographic testing for pulmonary embolism (PE). To help clinicians better target testing, this study sought to quantify the effect of risk factors for a positive quantitative D‐dimer in patients evaluated for PE.Methods:  This was a prospective, multicenter, observational study. Emergency department (ED) patients evaluated for PE with a quantitative D‐dimer were eligible for inclusion. The main outcome of interest was a positive D‐dimer. Odds ratio (ORs) and 95% confidence intervals (CIs) were determined by multivariable logistic regression. Adjusted estimates of relative risk were also calculated.Results:  A total of 4,346 patients had D‐dimer testing, of whom 2,930 (67%) were women. A total of 2,500 (57%) were white, 1,474 (34%) were black or African American, 238 (6%) were Hispanic, and 144 (3%) were of other race or ethnicity. The mean (±SD) age was 48 (±17) years. Overall, 1,903 (44%) D‐dimers were positive. Model fit was adequate (c‐statistic = 0.739, Hosmer and Lemeshow p‐value = 0.13). Significant positive predictors of D‐dimer positive included female sex; increasing age; black (vs. white) race; cocaine use; general, limb, or neurologic immobility; hemoptysis; hemodialysis; active malignancy; rheumatoid arthritis; lupus; sickle cell disease; prior venous thromboembolism (VTE; not under treatment); pregnancy and postpartum state; and abdominal, chest, orthopedic, or other surgery. Warfarin use was protective. In contrast, several variables known to be associated with PE were not associated with positive D‐dimer results: body mass index (BMI), estrogen use, family history of PE, (inactive) malignancy, thrombophilia, trauma within 4 weeks, travel, and prior VTE (under treatment).Conclusions:  Many factors are associated with a positive D‐dimer test. The effect of these factors on the usefulness of the test should be considered prior to ordering a D‐dimer.ACADEMIC EMERGENCY MEDICINE 2010; 17:589–597 © 2010 by the Society for Academic Emergency Medicine

Objectives:  The utility of D‐dimer testing for suspected pulmonary embolism (PE) can be limited by test specificity. The authors tested if the threshold of the quantitative D‐dimer can be varied according to pretest probability (PTP) of PE to increase specificity while maintaining a negative predictive value (NPV) of >99%.Methods:  This was a prospective, observational multicenter study of emergency department (ED) patients in the United States. Eligible patients had a diagnostic study ordered to evaluate possible PE. PTP was determined by the clinician’s unstructured estimate and the Wells score. Five different D‐dimer assays were used. D‐dimer test performance was measured using 1) standard thresholds and 2) variable threshold values: twice (for low PTP patients), equal (intermediate PTP patients), or half (high PTP patients) of standard threshold. Venous thromboembolism (VTE) within 45 days required positive imaging plus decision to treat.Results:  The authors enrolled 7,940 patients tested for PE, and clinicians ordered a quantitative D‐dimer for 4,357 (55%) patients who had PTPs distributed as follows: low (74%), moderate (21%), or high (4%). At standard cutoffs, across all PTP strata, quantitative D‐dimer testing had a test sensitivity of 94% (95% confidence interval [CI] = 91% to 97%), specificity of 58% (95% CI = 56% to 60%), and NPV of 99.5% (95% CI = 99.1% to 99.7%). If variable cutoffs had been used the overall sensitivity would have been 88% (95% CI = 83% to 92%), specificity 75% (95% CI = 74% to 76%), and NPV 99.1% (95% CI = 98.7% to 99.4%).Conclusions:  This large multicenter observational sample demonstrates that emergency medicine clinicians currently order a D‐dimer in the majority of patients tested for PE, including a large proportion with intermediate PTP and high PTP. Varying the D‐dimer’s cutoff according to PTP can increase specificity with no measurable decrease in NPV.

Introduction: In the prehospital setting, optimal endotracheal tube (ETT) depth may be approximated using the patient's sex or height, and assessed by auscultation. Even when using these methods, the ETTs still may be placed at inappropriate depths.Problem: This study assessed the inter-rater reliability and accuracy of manual cuff palpation (ballottement) at excluding an improperly placed ETT depth in adult patients.Methods: This is a prospective, observational, pilot study in a convenience sample of adults recently intubated in the prehospital, medical floor, intensive care unit, or emergency department settings of an urban, teaching hospital. Two physician participants separately performed ballottement on each intubated subject and rated the ballottement as none, weak, or strong prior to assessment of appropriate depth using a chest radiograph (CXR). Results were compared for simple agreement and compared to the CXR to estimate accuracy.Results: Of 163 patients, 27 (17%) had an inappropriate ETT depth. Physician assessments of ballottement agreed in 79% of patients (95% CI = 72-85%). Chest radiograph assessment found the ETT in the “strong” ballottement group properly placed in 93%, as compared to 77% in the “weak”, and 42% in the “none” groups. Combining “weak” and “strong” ballottement, the sensitivity was 96% (95% CI = 93–100%), specificity was 26% (95% CI = 9–43%), and accuracy was 85% (95% CI = 79–90%).Conclusions: Manual cuff palpation is a simple and reproducible technique that is sensitive, but nonspecific, in identifying intubations of appropriate depth.