Chee M. Chan

Resistant Pathogens in Nonnosocomial Pneumonia and Respiratory Failure: Is It Time To Refine the Definition of Health-care-Associated Pneumonia?

BACKGROUND The concept of health-care-associated pneumonia (HCAP) exists to identify patients infected with highly resistant pathogens. It is unclear how precise this concept is and how well it performs as a screening tool for resistance. METHODS We retrospectively identified patients presenting to the hospital with pneumonia complicated by respiratory failure. We examined the microbiology of these infections based on pneumonia type and determined the sensitivity and specificity of HCAP as a screen for resistance. Through logistic regression and modeling, we created a scoring tool for determining who may be infected with resistant pathogens. RESULTS The cohort included 190 subjects (37% with ARDS) and we noted resistant pathogens in 33%. Resistance was more common in HCAP (78% vs 44%, P = .001). HCAP alone performed poorly as a screening test (sensitivity and specificity 78.3% and 56.2%, respectively). Variables independently associated with a resistant organism included immunosuppression (adjusted odds ratio [AOR] 4.85, P < .001), long-term care admission (AOR 2.36, P = .029), and prior antibiotics (AOR 2.12, P = .099). A decision rule based only on these factors performed moderately well at identifying resistant infections. The presence of HCAP itself, based on meeting defined criteria, was not independently associated with resistance using logistic regression to control for covariates. CONCLUSIONS HCAP is common in patients presenting to the hospital with pneumonia leading to respiratory failure. The HCAP concept does not correlate well with the presence of infection due to a resistant pathogen. A simpler clinical decision rule based on select HCAP criteria performs as well as the HCAP concept for potentially guiding antibiotic decision making.

The validation and reproducibility of the pulmonary embolism severity index

Summary.  Background: Rapid, accurate risk stratification is paramount in managing patients with acute pulmonary embolism (PE). The PE Severity Index (PESI) is a simple tool that risk stratifies patients with acute PE. Objectives: We sought to validate the PESI as a predictor of short‐ and intermediate‐term mortality and to determine the inter‐rater variability. Patients/Methods: We retrospectively identified all patients with acute PE between October 2007 and February 2009. Two clinicians reviewed charts and independently scored PESI blinded to each other and to patient outcomes. Thirty‐ and 90‐day mortality served as study endpoints and vital status was assessed via the Social Security Death Index. To facilitate analyses, raw PESI score was converted into risk class groups (I–V) and further dichotomized into low risk (I–II) vs. high risk (III–V) groups. Intraclass correlation and the kappa statistic were used to determine inter‐rater variability. Results: The cohort included 302 subjects (mean age, 59.7 ± 17.2 years; 44% male). All‐cause 30‐ and 90‐day mortalities were 3.0% and 4.0%, respectively. The mortality rate increased as raw PESI score increased. Risk of death correlated with risk class (P < 0.001). There were no deaths in risk classes I–III, but 30‐ and 90‐day mortality for class V were 9.2% and 10.5%, respectively. Overall, mean PESI scores were similar between observers: 103.3 ± 39.3 and 96.5 ± 37.6 (P = NS). The inter‐rater variability was good (kappa = 0.69; P < 0.0001). Conclusions: The PESI correlates with 30‐ and 90‐day mortality. It represents a reproducible scoring tool to risk stratify patients with acute PE.

The Role for Optical Density in Heparin-Induced Thrombocytopenia: A Cohort Study

BACKGROUND Heparin-induced thrombocytopenia (HIT) is a serious complication of heparin utilization. An enzyme-linked immunosorbent assay (ELISA) is usually performed to assist in the diagnosis of HIT. ELISAs tend to be sensitive but lack specificity. We sought to use a new cutoff to define a positive HIT ELISA. METHODS We conducted a prospective observational study of hospitalized patients undergoing ELISA testing. All patients who underwent ELISA testing were eligible for inclusion (n = 496). Irrespective of the results, all subjects had confirmatory testing with a serotonin release assay (SRA). We compared a threshold optical density (OD) > 1.00 to the current definition of a positive ELISA (OD > 0.40) as a screening test for a positive SRA. We used sensitivity, specificity, and area under the receiver operating curve to determine whether an OD > 1.00 would improve diagnostic accuracy for HIT. RESULTS The SRA was positive in 10 patients (prevalence, 2.0%). Adjusting the definition of a positive HIT ELISA to > 1.00 maintained the sensitivity and negative predictive value at 100% in the cohort. The positive predictive value of the higher cutoff OD was more than triple the positive predictive value of an OD > 0.40 (41.7% vs 13.3%). No patient with a positive SRA had an OD measurement ≤ 1.00. CONCLUSIONS Increasing the OD threshold enhances specificity without noticeably compromising sensitivity. Altering the definition of the HIT ELISA could prevent unnecessary testing and/or treatment with non-heparin-based anticoagulants in patients with possible HIT. TRIAL REGISTRY ClinicalTrials.gov; No.: NCT00946400; URL: www.clinicaltrials.gov.

Venous Thromboembolic Disease in the Intensive Care Unit

Critically ill patients are at increased risk of developing venous thromboemboli (VTE). Risk factors that predispose them to acquiring VTE encompass factors that usually afflict the general medical population as well as factors attained in the intensive care unit (ICU) (e.g., sedation, mechanical ventilation). The poor cardiopulmonary reserve of this patient population is intolerant of even small pulmonary emboli (PE), which emphasizes the importance of preventing VTE from ever occurring. Indeed, the complications associated with hospital-acquired VTE increase morbidity, mortality, hospital length of stay, and costs. Without thromboprophylaxis, the incidence of VTE in the ICU ranges from 15 to 60%. Systematic implementation of VTE prophylaxis significantly reduces this rate and as a consequence, morbidity and mortality. In fact, prevention of VTE is so important that the American College of Chest Physicians (ACCP) developed guidelines on the use of routine VTE prophylaxis in critically ill patients. Therefore, upon admission, all ICU patients should be evaluated for and immediately prescribed the appropriate thromboprophylaxis therapy.

Diagnostics and epidemiology in ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) represents a common nosocomial complication arising in the intensive care unit. Owing to concerns regarding the excess morbidity related to VAP, multiple interventions for preventing this syndrome exist. Despite controversy regarding the optimal diagnostic approach to VAP, clinicians now face many external pressures to try to reduce, if not eliminate, VAP. In fact, some organizations consider VAP an entirely preventable event. However, any dialog regarding the outcomes and burden of VAP must rest on an understanding and appreciation of both the diagnostic complexities surrounding VAP and the epidemiology of this condition. In addition, the issues of diagnostics and epidemiology are closely linked. The means employed for diagnosing VAP certainly affect the observed prevalence of VAP. Despite these concerns, several general themes emerge in the literature describing VAP epidemiology. First, VAP rates vary based on the diagnostic approach employed. Second, select cohorts of patients are at high risk for VAP, and patient case-mix clearly influences the epidemiology of VAP. Third, rates of VAP appear higher outside the US, irrespective of the diagnostic paradigm utilized.

Comparing the pulmonary embolism severity index and the prognosis in pulmonary embolism scores as risk stratification tools

BACKGROUND Multiple risk stratification scoring systems exist to forecast outcomes in patients with acute pulmonary embolism (PE). OBJECTIVE We evaluated the comparative validity of the PE severity index (PESI) and the prognosis in pulmonary embolism (PREP) scores to predict mortality in acute PE. DESIGN Retrospective observational cohort study. SETTING Washington Hospital Center, Washington, DC. PATIENTS Consecutive adults (aged >18 years) diagnosed with acute PE. INTERVENTION The PESI and PREP scores were calculated. MEASUREMENTS Raw PESI scores were segregated into risk class (I-V) and then dichotomized into low (I-II) versus high (III-V) risk groups; the raw PREP scores were divided into low (0-7) versus high (>7) risk groups. The primary endpoint was 30-day and 90-day mortality. We determined the negative predictive value and computed the area under the receiver operating characteristics (AUROC) curves to compare the ability of these scoring tools. RESULTS The cohort consisted of 302 subjects. Thirty-day mortality was 3.0%, and 4.0% died within 90 days. The PESI and the PREP performed similarly (PESI AUROC: 0.858 [95% confidence interval (CI), 0.773-0.943] vs 0.719 [95% CI, 0.563-0.875] for PREP). Segregating these scores into risk categories did not affect their discriminatory power (AUROC: 0.684 [95% CI, 0.559-0.810] for PESI and 0.790 [95% CI, 0.679-0.903] for PREP). The negative predictive value for death of being classified as low risk by the PESI or PREP was 100% and 99%, respectively. CONCLUSIONS The PREP score performed comparably to the PESI score for identifying PE patients at low risk for short-term and intermediate-term mortality.

Economic and Outcomes Aspects of Venous Thromboembolic Disease

Critically ill patients clearly face an increased risk for developing venous thromboembolic disease (VTE). Upon admission, all critical care patients should be immediately assessed for and prescribed VTE prophylaxis as it can significantly reduce VTE occurrence, its potential sequelae,and costs associated with VTE treatment. The financial burden associated with VTE is substantial. Longer ICU and hospital lengths of stay, pharmacy costs, and further outpatient management all contribute considerably to the economic burden of disease. The importance of this healthcare issue should motivate hospital administrators and physicians to systematically initiate thromboprophylaxis in all ICU patients.

The pulmonary arteries, idiopathic pulmonary fibrosis, and lung transplantation: deciphering the connection.

www.chestpubs.org associated with a risk of major complications, often requires several procedures to control recurrent AF or postablation atrial tachycardia, and lacks evidence of improved clinical outcomes beyond rhythm control. Hence, catheter ablation is regarded as a second-line therapy for most patients and is reserved for those who fail initial AAD therapy, especially those with structural heart diseases or persistent AF. When performed by an experienced operator, catheter ablation may be considered an initial therapy (before AAD) for selected symptomatic patients with paroxysmal lone AF. In our view, the 2010 ESC guidelines represent an evolution in practice based on scientifi c advances since the 2006 guideline and a need for change arising from the availability of new anticoagulant and antiarrhythmic agents.

Original ResearchAntithrombotic TherapyThe Role for Optical Density in Heparin-Induced Thrombocytopenia

BACKGROUND Heparin-induced thrombocytopenia (HIT) is a serious complication of heparin utilization. An enzyme-linked immunosorbent assay (ELISA) is usually performed to assist in the diagnosis of HIT. ELISAs tend to be sensitive but lack specificity. We sought to use a new cutoff to define a positive HIT ELISA. METHODS We conducted a prospective observational study of hospitalized patients undergoing ELISA testing. All patients who underwent ELISA testing were eligible for inclusion (n = 496). Irrespective of the results, all subjects had confirmatory testing with a serotonin release assay (SRA). We compared a threshold optical density (OD) > 1.00 to the current definition of a positive ELISA (OD > 0.40) as a screening test for a positive SRA. We used sensitivity, specificity, and area under the receiver operating curve to determine whether an OD > 1.00 would improve diagnostic accuracy for HIT. RESULTS The SRA was positive in 10 patients (prevalence, 2.0%). Adjusting the definition of a positive HIT ELISA to > 1.00 maintained the sensitivity and negative predictive value at 100% in the cohort. The positive predictive value of the higher cutoff OD was more than triple the positive predictive value of an OD > 0.40 (41.7% vs 13.3%). No patient with a positive SRA had an OD measurement ≤ 1.00. CONCLUSIONS Increasing the OD threshold enhances specificity without noticeably compromising sensitivity. Altering the definition of the HIT ELISA could prevent unnecessary testing and/or treatment with non-heparin-based anticoagulants in patients with possible HIT. TRIAL REGISTRY ClinicalTrials.gov; No.: NCT00946400; URL: www.clinicaltrials.gov.

The effect of warmed fresh whole blood and acute lung injury in combat casualties

We thank Dixon and Glenn [1] for their thoughtful comments on our manuscript. We appreciate their positive statements about our studys methodology and sample size. We continue to feel that the issue of potential harm related to warm fresh whole blood (WFWB) is a concern. Even if the impact of WFWB on the risk for acute lung injury (ALI) is limited, it represents a crucial process of care variable. As such, it is one overwhich clinicians have control and thus canmodify exposure. Whether a patient has either blunt or penetrating trauma may be a major determinant of outcome and risk for ALI. However, that event precedes hospital care. Given that many major advances in critical care have come from understanding how the approach to resuscitation altersmorbidity and mortality, our efforts fit in this theme of attempting to appreciate the nexus between care delivery and outcome. In addition, in light of the austere environment of combat medical care, we believe that systematically studying the risks and benefits of WFWB reflects the only way to develop a means to optimize care for wounded soldiers. Our goal with