Validation of SeptiCyte RAPID to Discriminate Sepsis from Non-Infectious Systemic Inflammation

(1) Background: SeptiCyte RAPID is a molecular test for discriminating sepsis from non-infectious systemic inflammation, and for estimating sepsis probabilities. The objective of this study was the clinical validation of SeptiCyte RAPID, based on testing retrospectively banked and prospectively collected patient samples. (2) Methods: The cartridge-based SeptiCyte RAPID test accepts a PAXgene blood RNA sample and provides sample-to-answer processing in ~1 h. The test output (SeptiScore, range 0-15) falls into four interpretation bands, with higher scores indicating higher probabilities of sepsis. Retrospective (N = 356) and prospective (N = 63) samples were tested from adult patients in ICU who either had the systemic inflammatory response syndrome (SIRS), or were suspected of having/diagnosed with sepsis. Patients were clinically evaluated by a panel of three expert physicians blinded to the SeptiCyte test results. Results were interpreted under either the Sepsis-2 or Sepsis-3 framework. (3) Results: Under the Sepsis-2 framework, SeptiCyte RAPID performance for the combined retrospective and prospective cohorts had Areas Under the ROC Curve (AUCs) ranging from 0.82 to 0.85, a negative predictive value of 0.91 (sensitivity 0.94) for SeptiScore Band 1 (score range 0.1-5.0; lowest risk of sepsis), and a positive predictive value of 0.81 (specificity 0.90) for SeptiScore Band 4 (score range 7.4-15; highest risk of sepsis). Performance estimates for the prospective cohort ranged from AUC 0.86-0.95. For physician-adjudicated sepsis cases that were blood culture (+) or blood, urine culture (+)(+), 43/48 (90%) of SeptiCyte scores fell in Bands 3 or 4. In multivariable analysis with up to 14 additional clinical variables, SeptiScore was the most important variable for sepsis diagnosis. A comparable performance was obtained for the majority of patients reanalyzed under the Sepsis-3 definition, although a subgroup of 16 patients was identified that was called septic under Sepsis-2 but not under Sepsis-3. (4) Conclusions: This study validates SeptiCyte RAPID for estimating sepsis probability, under both the Sepsis-2 and Sepsis-3 frameworks, for hospitalized patients on their first day of ICU admission.

Neutrophil activation and neutrophil extracellular traps (NETs) in COVID-19 ARDS and immunothrombosis

Acute respiratory distress syndrome (ARDS) is an acute inflammatory condition with a dramatic increase in incidence since the beginning of the coronavirus disease 19 (COVID-19) pandemic. Neutrophils play a vital role in the immunopathology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by triggering the formation of neutrophil extracellular traps (NETs), producing cytokines including interleukin-8 (CXCL8), and mediating the recruitment of other immune cells to regulate processes such as acute and chronic inflammation, which can lead to ARDS. CXCL8 is involved in the recruitment, activation, and degranulation of neutrophils, and therefore contributes to inflammation amplification and severity of disease. Furthermore, activation of neutrophils also supports a prothrombotic phenotype, which may explain the development of immunothrombosis observed in COVID-19 ARDS. This review aims to describe hyperinflammatory ARDS due to SARS-CoV-2 infection. In addition, we address the critical role of polymorphonuclear neutrophils, inflammatory cytokines, and the potential targeting of CXCL8 in treating the hyperinflammatory ARDS population.

Investigating Unhealthy Alcohol Use As an Independent Risk Factor for Increased COVID-19 Disease Severity: Observational Cross-sectional Study

BACKGROUND

Unhealthy alcohol use (UAU) is known to disrupt pulmonary immune mechanisms and increase the risk of acute respiratory distress syndrome in patients with pneumonia; however, little is known about the effects of UAU on outcomes in patients with COVID-19 pneumonia. To our knowledge, this is the first observational cross-sectional study that aims to understand the effect of UAU on the severity of COVID-19.

OBJECTIVE

We aim to determine if UAU is associated with more severe clinical presentation and worse health outcomes related to COVID-19 and if socioeconomic status, smoking, age, BMI, race/ethnicity, and pattern of alcohol use modify the risk.

METHODS

In this observational cross-sectional study that took place between January 1, 2020, and December 31, 2020, we ran a digital machine learning classifier on the electronic health record of patients who tested positive for SARS-CoV-2 via nasopharyngeal swab or had two COVID-19 International Classification of Disease, 10th Revision (ICD-10) codes to identify patients with UAU. After controlling for age, sex, ethnicity, BMI, smoking status, insurance status, and presence of ICD-10 codes for cancer, cardiovascular disease, and diabetes, we then performed a multivariable regression to examine the relationship between UAU and COVID-19 severity as measured by hospital care level (ie, emergency department admission, emergency department admission with ventilator, or death). We used a predefined cutoff with optimal sensitivity and specificity on the digital classifier to compare disease severity in patients with and without UAU. Models were adjusted for age, sex, race/ethnicity, BMI, smoking status, and insurance status.

RESULTS

Each incremental increase in the predicted probability from the digital alcohol classifier was associated with a greater odds risk for more severe COVID-19 disease (odds ratio 1.15, 95% CI 1.10-1.20). We found that patients in the unhealthy alcohol group had a greater odds risk to develop more severe disease (odds ratio 1.89, 95% CI 1.17-3.06), suggesting that UAU was associated with an 89% increase in the odds of being in a higher severity category.

CONCLUSIONS

In patients infected with SARS-CoV-2, UAU is an independent risk factor associated with greater disease severity and/or death.

2212. Burden of Community-Acquired Pneumonia Attributable to Co-morbid Conditions in Adults

Background

Few studies have quantified the risk of community-acquired pneumonia (CAP) among adults with co-morbidities. Combining data from the population-based, prospective Etiology of Pneumonia in the Community study (EPIC) and the nationwide health-related Behavioral Risk Factor Surveillance System (BRFSS) telephone-survey, we estimated the annual risk of hospitalization for CAP among adults with co-morbidities.

Methods

We identified adults hospitalized with radiographic and clinical CAP at hospitals in Chicago, IL and Nashville, TN from July 2010 to June 2012. Using 2011 BRFSS data, we estimated the prevalence of the population with selected co-morbidities (chronic lung disease [CLD], cardiovascular disease [CVD], chronic kidney disease [CKD], or diabetes) in the EPIC study catchment counties, as well as the population without co-morbidities. We estimated the incidence of hospitalized CAP, age-adjusted relative risk (RR) using Poisson regression, and population attributable fraction for each co-morbidity.

Results

Among 2,061 adult patients enrolled in EPIC, 1,428 (69%) had at least one selected co-morbidity, most commonly CLD (42%) and CVD (35%). Among the adult population in the EPIC catchment area, 17% had ≥1 selected co-morbidity. The overall incidence of hospitalized CAP was 24.8/10,000, 118.7/10,000 among adults with ≥1 co-morbidity, and 11.2/10,000 among adults without a co-morbidity. Compared with patients without co-morbidities, the incidence of hospitalization for CAP was higher among patients with CLD (aRR: 20.7 [95% confidence interval [CI]: 20.0–21.5]), CKD (aRR: 14.5 [CI: 13.8–15.1]), CVD (aRR: 14.0 [CI: 13.5–14.6]), and diabetes (aRR: 6.2 [CI: 5.9–6.4]). While CLD and CVD accounted for high proportions of the incidence of CAP hospitalizations in the study population, the contribution of the selected co-morbidities varied by age groups (figure).

Conclusion

There is an increased risk of hospitalization for CAP among adults with co-morbidities, particularly chronic lung and cardiovascular disease. As a large portion of CAP is attributable to these co-morbidities, targeted public health interventions, such as vaccination and risk communication, need to be reinforced among these high-risk groups.

Disclosures

All authors: No reported disclosures.

Pneumococcal Community-Acquired Pneumonia Detected by Serotype-Specific Urinary Antigen Detection Assays

Background

Streptococcus pneumoniae is considered the leading bacterial cause of pneumonia in adults. Yet, it was not commonly detected by traditional culture-based and conventional urinary testing in a recent multicenter etiology study of adults hospitalized with community-acquired pneumonia (CAP). We used novel serotype-specific urinary antigen detection (SSUAD) assays to determine whether pneumococcal cases were missed by traditional testing.

Methods

We studied adult patients hospitalized with CAP at 5 hospitals in Chicago and Nashville (2010-2012) and enrolled in the Etiology of Pneumonia in the Community (EPIC) study. Traditional diagnostic testing included blood and sputum cultures and conventional urine antigen detection (ie, BinaxNOW). We applied SSUAD assays that target serotypes included in the 13-valent pneumococcal conjugate vaccine (PCV13) to stored residual urine specimens.

Results

Among 1736 patients with SSUAD and ≥1 traditional pneumococcal test performed, we identified 169 (9.7%) cases of pneumococcal CAP. Traditional tests identified 93 (5.4%) and SSUAD identified 76 (4.4%) additional cases. Among 14 PCV13-serotype cases identified by culture, SSUAD correctly identified the same serotype in all of them. Cases identified by SSUAD vs traditional tests were similar in most demographic and clinical characteristics, although disease severity and procalcitonin concentration were highest among those with positive blood cultures. The proportion of pneumonia cases caused by serotypes exclusively covered by PCV13 was not significantly different between the first and second July-June study periods (6.4% vs 4.0%).

Conclusions

Although restricted to the detection of only 13 serotypes, SSUAD testing substantially increased the detection of pneumococcal pneumonia among adults hospitalized with CAP.

Validation of a Host Response Assay, SeptiCyte LAB, for Discriminating Sepsis from Systemic Inflammatory Response Syndrome in the ICU

RATIONALE

A molecular test to distinguish between sepsis and systemic inflammation of noninfectious etiology could potentially have clinical utility.

OBJECTIVES

This study evaluated the diagnostic performance of a molecular host response assay (SeptiCyte LAB) designed to distinguish between sepsis and noninfectious systemic inflammation in critically ill adults.

METHODS

The study employed a prospective, observational, noninterventional design and recruited a heterogeneous cohort of adult critical care patients from seven sites in the United States (n = 249). An additional group of 198 patients, recruited in the large MARS (Molecular Diagnosis and Risk Stratification of Sepsis) consortium trial in the Netherlands ( www.clinicaltrials.gov identifier NCT01905033), was also tested and analyzed, making a grand total of 447 patients in our study. The performance of SeptiCyte LAB was compared with retrospective physician diagnosis by a panel of three experts.

MEASUREMENTS AND MAIN RESULTS

In receiver operating characteristic curve analysis, SeptiCyte LAB had an estimated area under the curve of 0.82-0.89 for discriminating sepsis from noninfectious systemic inflammation. The relative likelihood of sepsis versus noninfectious systemic inflammation was found to increase with increasing test score (range, 0-10). In a forward logistic regression analysis, the diagnostic performance of the assay was improved only marginally when used in combination with other clinical and laboratory variables, including procalcitonin. The performance of the assay was not significantly affected by demographic variables, including age, sex, or race/ethnicity.

CONCLUSIONS

SeptiCyte LAB appears to be a promising diagnostic tool to complement physician assessment of infection likelihood in critically ill adult patients with systemic inflammation. Clinical trial registered with www.clinicaltrials.gov (NCT01905033 and NCT02127502).

Physician agreement on the diagnosis of sepsis in the intensive care unit: estimation of concordance and analysis of underlying factors in a multicenter cohort

Background

Differentiating sepsis from the systemic inflammatory response syndrome (SIRS) in critical care patients is challenging, especially before serious organ damage is evident, and with variable clinical presentations of patients and variable training and experience of attending physicians. Our objective was to describe and quantify physician agreement in diagnosing SIRS or sepsis in critical care patients as a function of available clinical information, infection site, and hospital setting.

Methods

We conducted a post hoc analysis of previously collected data from a prospective, observational trial (N = 249 subjects) in intensive care units at seven US hospitals, in which physicians at different stages of patient care were asked to make diagnostic calls of either SIRS, sepsis, or indeterminate, based on varying amounts of available clinical information (clinicaltrials.gov identifier: NCT02127502). The overall percent agreement and the free-marginal, inter-observer agreement statistic kappa (κ_free) were used to quantify agreement between evaluators (attending physicians, site investigators, external expert panelists). Logistic regression and machine learning techniques were used to search for significant variables that could explain heterogeneity within the indeterminate and SIRS patient subgroups.

Results

Free-marginal kappa decreased between the initial impression of the attending physician and (1) the initial impression of the site investigator (κ_free 0.68), (2) the consensus discharge diagnosis of the site investigators (κ_free 0.62), and (3) the consensus diagnosis of the external expert panel (κ_free 0.58). In contrast, agreement was greatest between the consensus discharge impression of site investigators and the consensus diagnosis of the external expert panel (κ_free 0.79). When stratified by infection site, κ_free for agreement between initial and later diagnoses had a mean value + 0.24 (range − 0.29 to + 0.39) for respiratory infections, compared to + 0.70 (range + 0.42 to + 0.88) for abdominal + urinary + other infections. Bioinformatics analysis failed to clearly resolve the indeterminate diagnoses and also failed to explain why 60% of SIRS patients were treated with antibiotics.

Conclusions

Considerable uncertainty surrounds the differential clinical diagnosis of sepsis vs. SIRS, especially before organ damage has become highly evident, and for patients presenting with respiratory clinical signs. Our findings underscore the need to provide physicians with accurate, timely diagnostic information in evaluating possible sepsis.

Electronic supplementary material

The online version of this article (10.1186/s40560-019-0368-2) contains supplementary material, which is available to authorized users.

Real-world use of procalcitonin and other biomarkers among sepsis hospitalizations in the United States: A retrospective, observational study

Background

Sepsis management guidelines endorse use of biomarkers to support clinical assessment and treatment decisions in septic patients. The impact of biomarkers on improving patient outcomes remains uncertain.

Methods

Retrospective observational study of adult sepsis discharges between January 1, 2012, and December 31, 2015, from Premier Healthcare Database hospitals. Sepsis was defined by an All Patients Refined Diagnosis-Related Group code of 720 (septicemia and disseminated infections). Use of four biomarker strategies was evaluated based on hospital records: (i) >1 procalcitonin (PCT), (ii) 1 PCT, (iii) no PCT but ≥1 C-reactive protein (CRP) and/or lactate and (iv) no sepsis biomarkers. Associations between biomarker use and clinical and cost outcomes were examined. The primary outcome was impact of biomarker strategy on hospital costs per day.

Results

Among 933,591 adult sepsis discharges during the study period, 731,392 (78%) had biomarker tests ordered. In multivariable analyses, discharges with >1 PCT had higher hospital costs per day ($1,904; 95% confidence interval [CI] $1,896–$1,911) compared with discharges with no sepsis biomarkers ($1,606; 95% CI $1,658–$1,664). Discharges with >1 PCT also had greater illness severity and antimicrobial exposure compared with other biomarker-use groups. The adjusted odds of dying during hospital stay compared with being discharged were significantly lower for sepsis discharges with >1 PCT (0.64; 95% CI 0.61–0.67) and 1 PCT (0.88; 95% CI 0.85–0.91) compared with no sepsis biomarker use. The proportion of discharges with ≥1 PCT increased almost six-fold during the study; use of other biomarkers remained constant.

Conclusions

Between 2012 and 2015, PCT use among sepsis discharges increased six-fold while lactate and CRP use remained unchanged. PCT use was associated with decreased odds of in-hospital mortality but increased hospital costs per day. Serial biomarker monitoring may be associated with improved patient outcomes in the most critically ill septic patients.

Relationship Between Body Mass Index and Outcomes Among Hospitalized Patients With Community-Acquired Pneumonia

Background

The effect of body mass index (BMI) on community-acquired pneumonia (CAP) severity is unclear.

Methods

We investigated the relationship between BMI and CAP outcomes (hospital length of stay [LOS], intensive care unit [ICU] admission, and invasive mechanical ventilation) in hospitalized CAP patients from the Centers for Disease Control and Prevention Etiology of Pneumonia in the Community (EPIC) study, adjusting for age, demographics, underlying conditions, and smoking status (adults only).

Results

Compared with normal-weight children, odds of ICU admission were higher in children who were overweight (adjusted odds ratio [aOR], 1.7; 95% confidence interval [CI], 1.1-2.8) or obese (aOR, 2.1; 95% CI, 1.4-3.2), and odds of mechanical ventilation were higher in children with obesity (aOR, 2.7; 95% CI, 1.3-5.6). When stratified by asthma (presence/absence), these findings remained significant only in children with asthma. Compared with normal-weight adults, odds of LOS >3 days were higher in adults who were underweight (aOR, 1.6; 95% CI, 1.1-2.4), and odds of mechanical ventilation were lowest in adults who were overweight (aOR, 0.5; 95% CI, .3-.9).

Conclusions

Children who were overweight or obese, particularly those with asthma, had higher odds of ICU admission or mechanical ventilation. In contrast, adults who were underweight had longer LOS. These results underscore the complex relationship between BMI and CAP outcomes.

The characteristics and impact of source of infection on sepsis-related ICU outcomes

BACKGROUND

Source of infection is an independent predictor of sepsis-related mortality. To date, studies have failed to evaluate differences in septic patients based on the source of infection.

METHODS

Retrospective study of all patients with sepsis admitted to the ICU of a university hospital within a 12month time period.

RESULTS

Sepsis due to intravascular device and multiple sources had the highest number of positive blood cultures and microbiology whereas lung and abdominal sepsis had the least. The observed hospital mortality was highest for sepsis due to multiple sources and unknown cause, and was lowest when due to abdominal, genitourinary (GU) or skin/soft tissue. Patients with sepsis due to lungs, unknown and multiple sources had the highest rates of multi-organ failure, whereas those with sepsis due to GU and skin/soft tissue had the lowest rates. Those with multisource sepsis had a significantly higher median ICU length of stay and hospital cost.

CONCLUSION

There are significant differences in patient characteristics, microbiology positivity, organs affected, mortality, length of stay and cost based on the source of sepsis. These differences should be considered in future studies to be able to deliver personalized care.

Statin Use and Hospital Length of Stay Among Adults Hospitalized With Community-acquired Pneumonia

BACKGROUND

Prior retrospective studies suggest that statins may benefit patients with community-acquired pneumonia (CAP) due to antiinflammatory and immunomodulatory effects. However, prospective studies of the impact of statins on CAP outcomes are needed. We determined whether statin use was associated with improved outcomes in adults hospitalized with CAP.

METHODS

Adults aged ≥18 years hospitalized with CAP were prospectively enrolled at 3 hospitals in Chicago, Illinois, and 2 hospitals in Nashville, Tennessee, from January 2010-June 2012. Adults receiving statins before and throughout hospitalization (statin users) were compared with those who did not receive statins (nonusers). Proportional subdistribution hazards models were used to examine the association between statin use and hospital length of stay (LOS). In-hospital mortality was a secondary outcome. We also compared groups matched on propensity score.

RESULTS

Of 2016 adults enrolled, 483 (24%) were statin users; 1533 (76%) were nonusers. Statin users were significantly older, had more comorbidities, had more years of education, and were more likely to have health insurance than nonusers. Multivariable regression demonstrated that statin users and nonusers had similar LOS (adjusted hazard ratio [HR], 0.99; 95% confidence interval [CI], .88-1.12), as did those in the propensity-matched groups (HR, 1.03; 95% CI, .88-1.21). No significant associations were found between statin use and LOS or in-hospital mortality, even when stratified by pneumonia severity.

CONCLUSIONS

In a large prospective study of adults hospitalized with CAP, we found no evidence to suggest that statin use before and during hospitalization improved LOS or in-hospital mortality.

Economic evaluation of procalcitonin-guided antibiotic therapy in acute respiratory infections: a US health system perspective

BACKGROUND

Whether or not antibiotic stewardship protocols based on procalcitonin levels results in cost savings remains unclear. Herein, our objective was to assess the economic impact of adopting procalcitonin testing among patients with suspected acute respiratory tract infection (ARI) from the perspective of a typical US integrated delivery network (IDN) with a 1,000,000 member catchment area or enrollment.

METHODS

To conduct an economic evaluation of procalcitonin testing versus usual care we built a cost-impact model based on patient-level meta-analysis data of randomized trials. The meta-analytic data was adapted to the US setting by applying the meta-analytic results to US lengths of stay, costs, and practice patterns. We estimated the annual ARI visit rate for the one million member cohort, by setting (inpatient, ICU, outpatient) and ARI diagnosis.

RESULTS

In the inpatient setting, the costs of procalcitonin-guided compared to usual care for the one million member cohort was $2,083,545, compared to $2,780,322, resulting in net savings of nearly $700,000 to the IDN for 2014. In the ICU and outpatient settings, savings were $73,326 and $5,329,824, respectively, summing up to overall net savings of $6,099,927 for the cohort. RESULTS were robust for all ARI diagnoses. For the whole US insured population, procalcitonin-guided care would result in $1.6 billion in savings annually.

CONCLUSIONS

Our results show substantial savings associated with procalcitonin protocols of ARI across common US treatment settings mainly by direct reduction in unnecessary antibiotic utilization. These results are robust to changes in key parameters, and the savings can be achieved without any negative impact on treatment outcomes.

In-Hospital Pneumococcal Polysaccharide Vaccination Is Associated With Detection of Pneumococcal Vaccine Serotypes in Adults Hospitalized for Community-Acquired Pneumonia

During an etiology study of adults hospitalized for pneumonia, in which urine specimens were examined for serotype-specific pneumococcal antigen detection, we observed that some patients received 23-valent pneumococcal polysaccharide vaccine before urine collection. Some urine samples became positive for specific vaccine pneumococcal serotypes shortly after vaccination, suggesting false-positive test results.

Community-Acquired Pneumonia Requiring Hospitalization among U.S. Adults

BACKGROUND

Community-acquired pneumonia is a leading infectious cause of hospitalization and death among U.S. adults. Incidence estimates of pneumonia confirmed radiographically and with the use of current laboratory diagnostic tests are needed.

METHODS

We conducted active population-based surveillance for community-acquired pneumonia requiring hospitalization among adults 18 years of age or older in five hospitals in Chicago and Nashville. Patients with recent hospitalization or severe immunosuppression were excluded. Blood, urine, and respiratory specimens were systematically collected for culture, serologic testing, antigen detection, and molecular diagnostic testing. Study radiologists independently reviewed chest radiographs. We calculated population-based incidence rates of community-acquired pneumonia requiring hospitalization according to age and pathogen.

RESULTS

From January 2010 through June 2012, we enrolled 2488 of 3634 eligible adults (68%). Among 2320 adults with radiographic evidence of pneumonia (93%), the median age of the patients was 57 years (interquartile range, 46 to 71); 498 patients (21%) required intensive care, and 52 (2%) died. Among 2259 patients who had radiographic evidence of pneumonia and specimens available for both bacterial and viral testing, a pathogen was detected in 853 (38%): one or more viruses in 530 (23%), bacteria in 247 (11%), bacterial and viral pathogens in 59 (3%), and a fungal or mycobacterial pathogen in 17 (1%). The most common pathogens were human rhinovirus (in 9% of patients), influenza virus (in 6%), and Streptococcus pneumoniae (in 5%). The annual incidence of pneumonia was 24.8 cases (95% confidence interval, 23.5 to 26.1) per 10,000 adults, with the highest rates among adults 65 to 79 years of age (63.0 cases per 10,000 adults) and those 80 years of age or older (164.3 cases per 10,000 adults). For each pathogen, the incidence increased with age.

CONCLUSIONS

The incidence of community-acquired pneumonia requiring hospitalization was highest among the oldest adults. Despite current diagnostic tests, no pathogen was detected in the majority of patients. Respiratory viruses were detected more frequently than bacteria. (Funded by the Influenza Division of the National Center for Immunizations and Respiratory Diseases.).

Developing a New, National Approach to Surveillance for Ventilator-Associated Events: Executive Summary

This article is an executive summary of a report from the Centers for Disease Control and Prevention Ventilator-Associated Pneumonia Surveillance Definition Working Group, entitled “Developing a new, national approach to surveillance for ventilator-associated events” and published in Critical Care Medicine. The full report provides a comprehensive description of the Working Group process and outcome.

In September 2011, the Centers for Disease Control and Prevention (CDC) convened a Ventilator-Associated Pneumonia (VAP) Surveillance Definition Working Group to organize a formal process for leaders and experts of key stakeholder organizations to discuss the challenges of VAP surveillance definitions and to propose new approaches to VAP surveillance in adult patients (Table 1).

Developing a new, national approach to surveillance for ventilator-associated events*

OBJECTIVE

To develop and implement an objective, reliable approach to surveillance for ventilator-associated events in adult patients.

DESIGN

The Centers for Disease Control and Prevention (CDC) convened a Ventilator-Associated Pneumonia (VAP) Surveillance Definition Working Group in September 2011. Working Group members included representatives of stakeholder societies and organizations and federal partners.

MAIN RESULTS

The Working Group finalized a three-tier, adult surveillance definition algorithm for ventilator-associated events. The algorithm uses objective, readily available data elements and can identify a broad range of conditions and complications occurring in mechanically ventilated adult patients, including but not limited to VAP. The first tier definition, ventilator-associated condition (VAC), identifies patients with a period of sustained respiratory deterioration following a sustained period of stability or improvement on the ventilator, defined by changes in the daily minimum fraction of inspired oxygen or positive end-expiratory pressure. The second tier definition, infection-related ventilator-associated complication (IVAC), requires that patients with VAC also have an abnormal temperature or white blood cell count, and be started on a new antimicrobial agent. The third tier definitions, possible and probable VAP, require that patients with IVAC also have laboratory and/or microbiological evidence of respiratory infection.

CONCLUSIONS

Ventilator-associated events surveillance was implemented in January 2013 in the CDC's National Healthcare Safety Network. Modifications to improve surveillance may be made as additional data become available and users gain experience with the new definitions.

Developing a new, national approach to surveillance for ventilator-associated events

This article is an executive summary of a report from the Centers for Disease Control and Prevention Ventilator-Associated Pneumonia Surveillance Definition Working Group, entitled "Developing a New, National Approach to Surveillance for Ventilator-Associatied Events," published in Critical Care Medicine, by Magill SS, Klompas M, Balk R, Burns SM, Deutschman CS, et al. 2013;41(11):2467-2475. The full report provides a comprehensive description of the Working Group's process and outcome.

Roger C. Bone, MD and the evolving paradigms of sepsis

Severe sepsis and septic shock are frequent causes of ICU admission, commonly encountered complications during the course of hospitalization, and among the most common causes of death in the noncoronary ICU. Dr. Roger C. Bone was a pioneer in our struggles to improve the early recognition and management of severe sepsis and septic shock. Through his leadership and guidance, great strides were made to develop a uniform definition and to ensure the comparability of clinical research trials to evaluate new therapeutic strategies and antimediator agents. Dr. Bone also helped shape our understanding of the various stages or physiologic alterations that occur in the septic patient which also drove forward the development of new therapeutic strategies. This chapter briefly reviews the impact Roger Bone has had on our current understanding and approach to the septic patient.

Impact of the implementation of a sepsis protocol for the management of fluid-refractory septic shock: A single-center, before-and-after study

BACKGROUND

Evidence-based guidelines have been published for the acute management of severe sepsis and septic shock. Key goals of institution-driven protocols include timely fluid resuscitation and antibiotic selection, as well as source control.

OBJECTIVE

This study assessed the impact of a sepsis protocol on the timeliness of antibiotic administration, the adequacy of fluid resuscitation, and 28-day mortality in patients with fluid-refractory septic shock.

METHODS

This was a single-center, before-and-after study (18 months before July 2007 and 18 months after) with prospective data collection evaluating the outcomes of a sepsis protocol in adult patients with fluid-refractory septic shock. All patients received a fluid challenge and antibiotics; those who did not were excluded from this analysis. Preprotocol findings led to the development of the sepsis protocol, which emphasized fluid resuscitation, timely administration of antibiotic therapy, and collection of specimens for culture at the onset of septic shock. In the pre- and postprotocol phases of the study, data were collected prospectively and analyzed for demographic characteristics; Acute Physiology and Chronic Health Evaluation (APACHE) II score; appropriateness of fluid resuscitation; antibiotic use; number of vasopressor, ventilator, and intensive care unit (ICU) days; and 28-day mortality. Outcomes were measured prospectively at any time during the patient's hospital admission. The primary end points were the time to administration of antimicrobial therapy and the appropriateness of fluid resuscitation before and after implementation of the sepsis protocol.

RESULTS

A total of 118 patients were included in the analysis: 64 and 54 in the pre- and postprotocol groups, respectively. Patients in the preprotocol group were primarily women (53% [34/64]) and had a mean (SD) age of 61 (15.5) years and a mean APACHE II score of 28 (6.0). Patients in the postprotocol group were primarily men (54% [29/54]) and had a mean age of 52 (18.0) years and a mean APACHE II score of 27 (6.4). Implementation of the sepsis protocol resulted in a greater percentage of patients receiving timely antibiotic therapy (ie, within 4.5 hours of refractory shock; 85% [46/54] vs 56% [36/64]; P = 0.001) and adequate fluid resuscitation (72% [39/54] vs 31% [20/64]; P < 0.001) compared with the preprotocol group. Post hoc analysis found significant decreases in the number of vasopressor days (mean [SD], 3.8 [2.7] to 1.4 [1.5]; P < 0.001), ventilator days (9.1 [12.2] to 2.7 [4.0]; P < 0.001), and ICU days (12.3 [12.6] to 4.9 [3.9]; P < 0.001) in the postprotocol group. In-hospital mortality was not significantly different between the groups (survival 46% [28/61] before vs 54% [33/61] after the protocol). Multivariate analysis for predictors of in-hospital mortality identified an interval between shock and empiric antibiotic administration of >4.5 hours (odds ratio [OR] = 5.54; 95% CI, 1.91-16.07; P < 0.002), vasopressor duration in days (OR = 1.27; 95% CI, 1.01-1.59; P = 0.037), APACHE II score (OR = 1.14; 95% CI, 1.05-1.24; P = 0.003), and type of infection (community vs nosocomial, OR = 0.18; 95% CI, 0.05-0.61; P = 0.006) as significant predictors. The 28-day mortality decreased from 61% (39/64) to 33% (18/54) after implementation of the protocol (P = 0.004).

CONCLUSION

Implementation of a sepsis protocol emphasizing early administration of antibiotic therapy and adequate fluid resuscitation was associated with improved clinical outcomes and lower 28-day mortality in patients with fluid-refractory septic shock at this institution.

Sepsis in cirrhosis: report on the 7th meeting of the International Ascites Club

Sepsis is a systemic inflammatory response to the presence of infection, mediated via the production of many cytokines, including tumour necrosis factor (TNF-), interleukin (IL)-6, and IL-1, which cause changes in the circulation and in the coagulation cascade. There is stagnation of blood flow and poor oxygenation, subclinical coagulopathy with elevated D-dimers, and increased production of superoxide from nitric oxide synthase. All of these changes favour endothelial apoptosis and necrosis as well as increased oxidant stress. Reduced levels of activated protein C, which is normally anti-inflammatory and antiapoptotic, can lead to further tissue injury. Cirrhotic patients are particularly susceptible to bacterial infections because of increased bacterial translocation, possibly related to liver dysfunction and reduced reticuloendothelial function. Sepsis ensues when there is overactivation of pathways involved in the development of the sepsis syndrome, associated with complications such as renal failure, encephalopathy, gastrointestinal bleed, and shock with decreased survival. Thus the treating physician needs to be vigilant in diagnosing and treating bacterial infections in cirrhosis early, in order to prevent the development and downward spiral of the sepsis syndrome. Recent advances in management strategies of infections in cirrhosis have helped to improve the prognosis of these patients. These include the use of prophylactic antibiotics in patients with gastrointestinal bleed to prevent infection and the use of albumin in patients with spontaneous bacterial peritonitis to reduce the incidence of renal impairment. The use of antibiotics has to be judicious, as their indiscriminate use can lead to antibiotic resistance with potentially disastrous consequences.

Recombinant platelet-activating factor acetylhydrolase to prevent acute respiratory distress syndrome and mortality in severe sepsis: Phase IIb, multicenter, randomized, placebo-controlled, clinical trial

OBJECTIVE

Platelet-activating factor (PAF) is a potent proinflammatory mediator implicated in the pathogenesis of both severe sepsis and acute respiratory distress syndrome. One of the regulatory pathways for PAF involves degradation to the inactive metabolite lyso-PAF by the enzyme PAF acetylhydrolase (PAF-AH). Because reduced concentrations of the natural form of PAF-AH have been reported in septic patients, the present study was conducted to determine whether treatment with recombinant human PAF-AH (rPAF-AH, Pafase) was safe when administered after the onset of severe sepsis and whether it decreases the prevalence of acute respiratory distress syndrome and 28-day all-cause mortality.

DESIGN

A prospective, randomized, double-blind, placebo-controlled, multicenter trial.

SETTING

Thirty-three medical and surgical intensive care units located in the United States.

PATIENTS

A total of 127 patients with severe sepsis, but without established acute respiratory distress syndrome, were enrolled in the study. Randomization occurred within 12 hrs of the onset of severe sepsis. Patients then received 1.0 mg/kg rPAF-AH (n = 45), 5.0 mg/kg rPAF-AH (n = 39), or placebo (n = 43) administered intravenously, once daily, for five consecutive days.

MEASUREMENTS AND MAIN RESULTS

Demographic and baseline clinical characteristics of the three treatment groups were similar, except for a significantly higher prevalence of respiratory tract infections as the cause of severe sepsis in patients treated with 1.0 mg/kg rPAF-AH. There were no treatment-related deaths, and the overall prevalence of adverse events was similar among rPAF-AH-treated and placebo-treated patients. There were no significant differences in the prevalence of acute respiratory distress syndrome among the three treatment groups. However, 28-day all-cause mortality was 21% in the 1.0 mg/kg rPAF-AH group, 28% in the 5.0 mg/kg rPAF-AH group, and 44% in the placebo group (overall chi-square p =.07; 1.0 mg/kg rPAF-AH vs. placebo, p =.03). A trend toward reduced multiple organ dysfunction also was observed in the 1.0 mg/kg rPAF-AH group compared with the placebo group (p =.11).

CONCLUSION

The results from this study indicate that rPAF-AH was well tolerated and should be pursued as a potential new treatment to decrease mortality in patients with severe sepsis.

Therapeutic use of antithrombin concentrate in sepsis

Sepsis and its associated complications of disseminated intravascular coagulation (DIC) and multiple organ dysfunction syndrome (MODS) continue to be a major cause of morbidity and mortality. Improved detection of all forms of DIC is essential to assure earlier diagnosis. Studies already indicate that the therapeutic use of antithrombin (AT) concentrate may produce a more positive outcome for sepsis-associated DIC. If DIC could be identified earlier and AT concentrate could then be given earlier in the sepsis continuum, study results for the use of AT concentrate in humans might reveal a statistically significant difference versus placebo, and the efficacy of AT concentrate for this syndrome is more likely to be proved. Fixed-bolus doses of AT concentrate based on body weight are currently preferred, but improved, user-friendly assays for plasma AT levels would permit more rapid turnaround time for AT results and could help fine-tune the use of AT concentrate to the specific needs of each patient. Clinical trials involving the therapeutic use of AT concentrate in sepsis should continue, and it can be hoped that their design will reflect the concepts and conclusions offered by this panel of investigators.

Adult respiratory distress syndrome. Sequence and importance of development of multiple organ failure. The Prostaglandin E1 Study Group

STUDY OBJECTIVE

To determine the epidemiology of multiple organ failure (MOF) in patients with the adult respiratory distress syndrome.

PATIENTS

We followed up 50 patients with serial determinations of respiratory and nonrespiratory organ function for seven days after diagnosis.

DESIGN

Data were stratified between patients who died and those who survived (defined as hospital discharge).

MEASUREMENTS AND RESULTS

Values that did not differ at any time between the two groups of patients included oxygen availability, oxygen consumption, oxygen extraction, PaCO2, respiratory rate, heart rate, systolic blood pressure, cardiac output, stroke index, systemic vascular resistance, and temperature. Patients who died had greater defects in oxygenation (from day 1 through day 7). They also exhibited decreased arterial oxygen content (from day 1 to day 4), decreased mixed venous oxygen content (day 1), increased peak inspiratory pressure (present on day 2, persisted to day 5, reappeared on day 7), decreased diastolic blood pressure (seen on days 1 through 3, reappeared on day 7), and increased mean pulmonary artery pressure (seen on days 2 and 3). Nonsurvivors also exhibited greater degrees of thrombocytopenia (from day 1 to day 4). Decreases in pH (seen on day 1, reappeared from days 4 to 7), abnormalities in liver function (seen only on day 1), and increases in serum creatinine levels (appeared on day 7) were also observed.

CONCLUSIONS

Multiorgan dysfunction (MOD) was frequently observed in both groups of patients. Alterations in organ function and the pattern of abnormalities were often subtle and would not be characterized as significant organ dysfunction by most available organ scoring systems. Adult respiratory distress syndrome is a manifestation of systemic disease produced by widespread increases in endothelial permeability; lung dysfunction dominates the early clinical course. When respiratory function is supported, it becomes evident that alterations occur in other organs. Multiorgan failure is really a misnomer; the term emphasizes end-stage changes. Multiorgan dysfunction is common and often resolves without progressing to MOF. Alternatively, MOD can progress to MOF.

Differential effects of beta-adrenergic blockade on P0.1 and mean inspiratory flow

To quantitatively examine and compare the effects of beta-adrenergic blockade on ventilation, we studied 20 healthy volunteers during inhalation of room air and at steady state CO2 (2.0, 4.4, 6.0%) following a single oral dose of bupranolol (vs. placebo). During room air breathing, minute ventilation (VE) and mean inspiratory flow (VT/TI) were significantly reduced after beta-blockade with a concomitant increase in blood PaCO2 (p less than 0.01). The timing factor TI/Ttot and mouth occlusion pressure P0.1 remained unchanged. These differences were, as shown from calculated effective alveolar ventilation, mainly attributed to a decrease in physiological dead space ventilation following beta-blockade. With a stepwise increase in FICO2, the difference in PaCO2 between placebo and bupranolol tended to approach zero, whereas VE and VT/TI remained significantly lower during beta-blockade (P less than 0.05). In contrast, no difference existed in P0.1 between bupranolol and placebo. We suggest that (1) respiratory drive assessed by P0.1 is unaffected by beta-blockade and (2) mean inspiratory flow depends also on CO2 elimination characteristics, which are influenced by beta-blockade.

Classification of acute respiratory failure

Acute respiratory failure can result from a wide variety of etiologies. Hypoxemia is the hallmark of this condition and is responsible for the major clinical signs and symptoms. The use of arterial blood gas analysis is the cornerstone of diagnosis and is also critical in the subsequent evaluation of the effectiveness of therapy. Treatment must be individualized and coordinated in the setting of an intensive care unit.