Prediction of mortality in febrile medical patients: How useful are systemic inflammatory response syndrome and sepsis criteria?

Baroreceptor Modulation of the Cardiovascular System, Pain, Consciousness, and Cognition

Baroreceptors are mechanosensitive elements of the peripheral nervous system that maintain cardiovascular homeostasis by coordinating the responses to external and internal environmental stressors. While it is well known that carotid and cardiopulmonary baroreceptors modulate sympathetic vasomotor and parasympathetic cardiac neural autonomic drive, to avoid excessive fluctuations in vascular tone and maintain intravascular volume, there is increasing recognition that baroreceptors also modulate a wide range of non-cardiovascular physiological responses via projections from the nucleus of the solitary tract to regions of the central nervous system, including the spinal cord. These projections regulate pain perception, sleep, consciousness, and cognition. In this article, we summarize the physiology of baroreceptor pathways and responses to baroreceptor activation with an emphasis on the mechanisms influencing cardiovascular function, pain perception, consciousness, and cognition. Understanding baroreceptor-mediated effects on cardiac and extra-cardiac autonomic activities will further our understanding of the pathophysiology of multiple common clinical conditions, such as chronic pain, disorders of consciousness (e.g., abnormalities in sleep-wake), and cognitive impairment, which may result in the identification and implementation of novel treatment modalities. © 2021 American Physiological Society. Compr Physiol 11:1373-1423, 2021.

Predicting Adverse Outcomes for Febrile Patients in the Emergency Department Using Sparse Laboratory Data: Development of a Time Adaptive Model

BACKGROUND

A timely decision in the initial stages for patients with an acute illness is important. However, only a few studies have determined the prognosis of patients based on insufficient laboratory data during the initial stages of treatment.

OBJECTIVE

This study aimed to develop and validate time adaptive prediction models to predict the severity of illness in the emergency department (ED) using highly sparse laboratory test data (test order status and test results) and a machine learning approach.

METHODS

This retrospective study used ED data from a tertiary academic hospital in Seoul, Korea. Two different models were developed based on laboratory test data: order status only (OSO) and order status and results (OSR) models. A binary composite adverse outcome was used, including mortality or hospitalization in the intensive care unit. Both models were evaluated using various performance criteria, including the area under the receiver operating characteristic curve (AUC) and balanced accuracy (BA). Clinical usefulness was examined by determining the positive likelihood ratio (PLR) and negative likelihood ratio (NLR).

RESULTS

Of 9491 eligible patients in the ED (mean age, 55.2 years, SD 17.7 years; 4839/9491, 51.0% women), the model development cohort and validation cohort included 6645 and 2846 patients, respectively. The OSR model generally exhibited better performance (AUC=0.88, BA=0.81) than the OSO model (AUC=0.80, BA=0.74). The OSR model was more informative than the OSO model to predict patients at low or high risk of adverse outcomes (P<.001 for differences in both PLR and NLR).

CONCLUSIONS

Early-stage adverse outcomes for febrile patients could be predicted using machine learning models of highly sparse data including test order status and laboratory test results. This prediction tool could help medical professionals who are simultaneously treating the same patient share information, lead dynamic communication, and consequently prevent medical errors.

A Comparative Review of Equine SIRS, Sepsis, and Neutrophils

The most recent definition of sepsis in human medicine can be summarized as organ dysfunction caused by a dysregulated host response to infection. In equine medicine, although no consensus definition is available, sepsis is commonly described as a dysregulated host systemic inflammatory response to infection. Defense against host infection is the primary role of innate immune cells known as neutrophils. Neutrophils also contribute to host injury during sepsis, making them important potential targets for sepsis prevention, diagnosis, and treatment. This review will present both historical and updated perspectives on the systemic inflammatory response (SIRS) and sepsis; it will also discuss the impact of sepsis on neutrophils, and the impact of neutrophils during sepsis. Future identification of clinically relevant sepsis diagnosis and therapy depends on a more thorough understanding of disease pathogenesis across species. To gain this understanding, there is a critical need for research that utilizes a clearly defined, and consistently applied, classification system for patients diagnosed with, and at risk of developing, sepsis.

Comparison of diagnostic and prognostic utility of lactate and procalcitonin for sepsis in adult cancer patients presenting to emergency department with systemic inflammatory response syndrome

Objectives

Differentiating sepsis from other noninfectious causes of systemic inflammatory response syndrome (SIRS) in cancer patients is often challenging. Although lactate and procalcitonin have been studied extensively regarding sepsis management, little is known about their utility in cancer patients.

This study aimed to compare the diagnostic and prognostic utility of lactate and procalcitonin for sepsis in cancer patients.

Material and methods

This prospective case-control study was conducted with adult cancer patients presenting to emergency department (ED) with at least two SIRS criteria. The infection status of each patient was determined retrospectively.

Main diagnostic variables were calculated for diagnostic and prognostic utilities of lactate and procalcitonin.

Results

Among 86 patients, mean age was 61. Twenty-two (25.6%) were determined in the sepsis group.

In the ROC analysis, a lactate value of 1 mmol/L predicted sepsis with 86.36% (95%CI: 65.1%–97.1%) sensitivity and 28.12% (95%CI: 17.6%–40.76%) specificity. A procalcitonin value of 0.8 ng/mL yielded a sensitivity of 63.64% (95%CI: 40.7%–82.8%) and 76.56% (95%CI: 63.4%–86.2%) specificity for differential diagnosis of sepsis in cancer patients.

Lactate and procalcitonin showed similar abilities in differentiating sepsis from non-infective SIRS in cancer patients [AUROCs of 0.638 (95%CI:0.527–0.739) vs 0.637 (95%CI:0.527–0.738), respectively. p = 0.994].

They were also similar in predicting poor clinical outcome with AUROCs of 0.629 (95%CI:0.518–0.731) and 0.584 (95%CI: 0.473–0.69), respectively (p = 0.577).

Conclusions

The results of this study indicated that, none of the lactate and procalcitonin can be recommended alone to differentiate sepsis from non-infectious SIRS and to predict the poor clinical outcomes in adult cancer patients with SIRS in the ED.

The Frequency of White Blood Cell and Temperature Events During Mechanical Ventilation and Their Association With Ventilator-Associated Events

BACKGROUND

Changes in white blood cell (WBC) counts and/or temperature could have important implications in patients on ventilators, but the frequency of these events is uncertain.

METHODS

We reviewed the medical records from 281 ventilation episodes in our medical intensive care unit to determine patient characteristics and the indications for ventilation. We determined the number of days during each ventilation episode in which the temperature (<96.8°F, >100.4°F) or WBC count (<4000/µL, >12 000/µL) was out of the normal range.

RESULTS

This study included 257 patients with a mean Acute Physiology and Chronic Health Evaluation 2 score of 13.5 ± 5.9 and a mean initial Pao₂/Fio₂ of 210 ± 110. The median number of ventilator days was 4 (interquartile range, 3-9). One hundred ninety-six of 275 eligible ventilator episodes (71.3%) had 1 or more temperature events, and 194 of 253 eligible ventilator episodes (76.7%) had 1 or more WBC events. Nineteen patients met the Center for Disease Control criteria for a ventilator-associated event (VAE). Twelve patients had an increased WBC count during the VAE period, and 11 had an increased temperature during this period.

CONCLUSIONS

White blood cell counts and temperature events occur frequently in patients on ventilators and need evaluation but do not reliably identify patients with ventilator-associated complications.

An external validation study of a clinical prediction rule for medical patients with suspected bacteraemia

OBJECTIVE

The objective of this study was to externally validate a clinical prediction rule (CPR)-the 'Shapiro criteria'-to predict bacteraemia in an acute medical unit (AMU).

METHODS

Prospectively collected data, retrospectively evaluated over 11 months in an AMU in the UK. From 4810 admissions, 635 patients (13%) had blood cultures (BCs) performed. The 100 cases of true bacteraemia were compared with a randomly selected sample of 100 control cases where BCs were sterile.

RESULTS

To predict bacteraemia (at a cut-off score of two points), the Shapiro criteria had a sensitivity of 97% (95% CIs 91% to 99%), specificity 37% (28% to 47%), positive likelihood ratio 1.54 (1.3 to 1.8) and a negative likelihood ratio of 0.08 (0.03 to 0.25). The area under the receiver operating curve was 0.80 (0.74 to 0.86), and the Hosmer-Lemeshow p value was 0.45.

CONCLUSIONS

A cut-off score of two points on the Shapiro criteria had high sensitivity to predict bacteraemia in a study of acute general medical admissions. Application of the rule in patients being considered for a BC could identify those at low risk of bacteraemia. Though the model demonstrated good discrimination, the lengthy number of variables (13) and difficulty automating the CPR may limit its use.

Clinical Epidemiology of SIRS and Sepsis in Newly Admitted Children

OBJECTIVE

To assess the clinical and demographic profile of Systemic Inflammatory Response Syndrome (SIRS) and sepsis, among newly admitted children in different age groups in a hospital in North India.

METHODS

This prospective study was conducted at a referral care centre in Northern India. All children, age group 0 to <18 y, admitted on days selected for study were screened and those with abnormal temperature and abnormal leukocyte count were included for further assessment. A total of twenty "24 h" periods were randomly chosen during the study period. Patients were assessed according to age specific vital signs and laboratory values to diagnose Systemic Inflammatory Response Syndrome (SIRS) and sepsis and to gain clinical and demographic data. The criteria laid at International consensus conference, 2002, were used to define patients as SIRS, Sepsis, Severe sepsis and Septic shock.

RESULTS

During the study period, a total of 865 patients were screened for SIRS. Prevalence of SIRS amongst hospitalised children was 23 % (n = 201). Seventy nine percent (n = 159) of patients had infection associated SIRS and 21 % (42) had non-infective SIRS. Sixty four percent (n = 129) SIRS patients had uncomplicated sepsis, 15 % (n = 30) patients fulfilled criteria for severe sepsis. Out of the latter 30, 19 had septic shock. Organ dysfunction in SIRS was noted in 25 % (n = 51). 37.25 % (n = 19) had multiple organ dysfunction syndrome (MODS). The most common organism isolated was Staphylococcus aureus (n = 9). Focus of infection in majority was pulmonary (44 %). Mean duration of antibiotic therapy and hospital stay in the SIRS group were 6.4 and 6.5 d respectively. In the group without SIRS, mean duration were 2.44 d and 3.07 d respectively The differences were statistically significant.

CONCLUSIONS

In conclusion, the proportion of sepsis contributing to SIRS is high in a tertiary care hospital. Therefore rapid recognition of SIRS is essential. Goal directed treatment of sepsis is also important so that high mortality associated with severe sepsis and septic shock are prevented.

Severe sepsis and systemic inflammatory response syndrome in emergency department patients with suspected severe infection

BACKGROUND

Severe sepsis is a common condition with a reported high mortality, but most studies have been confined to intensive care unit (ICU) populations. The systemic inflammatory response syndrome (SIRS) has been used to define sepsis, however its usefulness has been questioned. Our aim was to describe the prevalence and clinical impact of severe sepsis and SIRS in patients admitted from the emergency department (ED) with a suspected serious infection.

METHODS

Four hundred and four adult patients were enrolled prospectively from the ED. Variables defining severe sepsis and SIRS were measured and the relationship between severe sepsis, SIRS, and the clinical course was analyzed.

RESULTS

Infections were diagnosed in 344 patients (85%). The overall mortality rate at 28 days was 2.7%, and 4.5% of patients were treated in the ICU. Patients with severe sepsis within 24 h of admission (42%) were more likely to suffer a critical course (ICU admission 9.0%, death 5.1%; p < 0.001). While SIRS was observed in 72% of the subjects at presentation, it was not associated with severe sepsis within 24 h or a subsequent critical course. Furthermore, 23% of patients with severe sepsis within 24 h did not present with SIRS.

CONCLUSIONS

Severe sepsis was a common condition among ED patients with a clinically suspected serious infection. Mortality was low compared with results from the ICU setting, suggesting that severe sepsis is a more benign disease than earlier reported. As a tool for the definition of sepsis and for the selection of patients for clinical sepsis trials, SIRS lacks acceptable discriminative ability in an ED population with a high prevalence of serious infections.

Value of soluble TREM-1, procalcitonin, and C-reactive protein serum levels as biomarkers for detecting bacteremia among sepsis patients with new fever in intensive care units: a prospective cohort study

Background

The purpose of this study was to explore the diagnostic value of soluble triggering receptor expressed on myeloid cells 1 (sTREM-1), procalcitonin (PCT), and C-reactive protein (CRP) serum levels for differentiating sepsis from SIRS, identifying new fever caused by bacteremia, and assessing prognosis when new fever occurred.

Methods

We enrolled 144 intensive care unit (ICU) patients: 60 with systemic inflammatory response syndrome (SIRS) and 84 with sepsis complicated by new fever at more than 48 h after ICU admission. Serum sTREM-1, PCT, and CRP levels were measured on the day of admission and at the occurrence of new fever (>38.3°C) during hospitalization. Based on the blood culture results, the patients were divided into a blood culture-positive bacteremia group (33 patients) and blood culture-negative group (51 patients). Based on 28-day survival, all patients, both blood culture-positive and -negative, were further divided into survivor and nonsurvivor groups.

Results

On ICU day 1, the sepsis group had higher serum sTREM-1, PCT, and CRP levels compared with the SIRS group (P <0.05). The areas under the curve (AUC) for these indicators were 0.868 (95% CI, 0.798–0.938), 0.729 (95% CI, 0.637–0.821), and 0.679 (95% CI, 0.578–0.771), respectively. With 108.9 pg/ml as the cut-off point for serum sTREM-1, sensitivity was 0.83 and specificity was 0.81. There was no statistically significant difference in serum sTREM-1 or PCT levels between the blood culture-positive and -negative bacteremia groups with ICU-acquired new fever. However, the nonsurvivors in the blood culture-positive bacteremia group had higher levels of serum sTREM-1 and PCT (P <0.05), with a prognostic AUC for serum sTREM-1 of 0.868 (95% CI, 0.740–0.997).

Conclusions

Serum sTREM-1, PCT, and CRP levels each have a role in the early diagnosis of sepsis. Serum sTREM-1, with the highest sensitivity and specificity of all indicators studied, is especially notable. sTREM-1, PCT, and CRP levels are of no use in determining new fever caused by bacteremia in ICU patients, but sTREM-1 levels reflect the prognosis of bacteremia.

Trial registration

ClinicalTrial.gov identifier NCT01410578

The usefulness of procalcitonin and C-reactive protein as early diagnostic markers of bacteremia in cancer patients with febrile neutropenia

Purpose

Procalcitonin (PCT) and C-reactive protein (CRP) are well known inflammatory markers. This study was designed to determine whether PCT and CRP are useful as early diagnostic markers for bacteremia in cancer patients with febrile neutropenia (FN) in the emergency department (ED).

Materials and Methods

In this retrospective study, 286 episodes of FN in the ED were consecutively included between June 2009 and August 2010. From medical records, clinical characteristics including PCT and CRP were extracted and analyzed.

Results

Bacteremia was identified in 38 (13.3%) of the 286 episodes. The median values of PCT (2.8 ng/mL vs. 0.0 ng/mL, p=0.000) and CRP (15.9 mg/dL vs. 5.6 mg/dL, p=0.002) were significantly higher in the group with bacteremia compared to the group without bacteremia. In univariate analysis, elevated PCT (>0.5 ng/mL) and CRP (>10 mg/dL) as well as older age, hypotension, tachycardia, tachypnea, and high body temperature were significantly associated with bacteremia. On multivariate analysis, elevated PCT (>0.5 ng/mL) (odds ratio [OR], 3.6; 95% confidence interval [CI], 1.4 to 9.2; p<0.01) and tachypnea (OR, 3.4; 95% CI, 1.4 to 8.5; p<0.01) were independent early diagnostic markers for bacteremia in FN patients. The area under the curve of PCT was 74.8% (95% CI, 65.1 to 84.6%) and that of CRP was 65.5% (95% CI, 54.8 to 76.1%). With a PCT cut-off value of 0.5 ng/mL, sensitivity and specificity were 60.5% and 82.3%, respectively, while the sensitivity and specificity were 57.6% and 67.3%, respectively, with a CRP cutoff of 10 mg/dL.

Conclusion

These findings suggest that PCT is a useful early diagnostic marker for the detection of bacteremia in FN at the ED and has better diagnostic value than CRP.

Patterns of unexpected in-hospital deaths: a root cause analysis

BACKGROUND

Respiratory alarm monitoring and rapid response team alerts on hospital general floors are based on detection of simple numeric threshold breaches. Although some uncontrolled observation trials in select patient populations have been encouraging, randomized controlled trials suggest that this simplistic approach may not reduce the unexpected death rate in this complex environment. The purpose of this review is to examine the history and scientific basis for threshold alarms and to compare thresholds with the actual pathophysiologic patterns of evolving death which must be timely detected.

METHODS

The Pubmed database was searched for articles relating to methods for triggering rapid response teams and respiratory alarms and these were contrasted with the fundamental timed pathophysiologic patterns of death which evolve due to sepsis, congestive heart failure, pulmonary embolism, hypoventilation, narcotic overdose, and sleep apnea.

RESULTS

In contrast to the simplicity of the numeric threshold breach method of generating alerts, the actual patterns of evolving death are complex and do not share common features until near death. On hospital general floors, unexpected clinical instability leading to death often progresses along three distinct patterns which can be designated as Types I, II and III. Type I is a pattern comprised of hyperventilation compensated respiratory failure typical of congestive heart failure and sepsis. Here, early hyperventilation and respiratory alkalosis can conceal the onset of instability. Type II is the pattern of classic CO2 narcosis. Type III occurs only during sleep and is a pattern of ventilation and SPO2 cycling caused by instability of ventilation and/or upper airway control followed by precipitous and fatal oxygen desaturation if arousal failure is induced by narcotics and/or sedation.

CONCLUSION

The traditional threshold breach method of detecting instability on hospital wards was not scientifically derived; explaining the failure of threshold based monitoring and rapid response team activation in randomized trials. Furthermore, the thresholds themselves are arbitrary and capricious. There are three common fundamental pathophysiologic patterns of unexpected hospital death. These patterns are too complex for early detection by any unifying numeric threshold. New methods and technologies which detect and identify the actual patterns of evolving death should be investigated.

Procalcitonin as a marker for the detection of bacteremia and sepsis in the emergency department

Rapid diagnosis of bloodstream infections (BSIs) in the emergency department (ED) is challenging, with turnaround times exceeding the timeline for rapid diagnosis. We studied the usefulness of procalcitonin as a marker of BSI in 367 adults admitted to our ED with symptoms of systemic infection. Serum samples obtained at the same time as blood cultures were available from 295 patients. Procalcitonin levels were compared with blood culture results and other clinical data obtained during the ED visit. Procalcitonin levels of less than 0.1 ng/mL were considered negative; all other levels were considered positive. In 16 patients, there was evidence of BSI by blood culture, and 12 (75%) of 16 patients had a procalcitonin level of more than 0.1 ng/mL. In 186 (63.1%) of 295 samples, procalcitonin values were less than 0.1 ng/mL, and all were culture negative. With a calculated threshold of 0.1475 ng/mL for procalcitonin, sensitivity and specificity for the procalcitonin assay were 75% and 79%, respectively. The positive predictive value was 17% and the negative predictive value 98% compared with blood cultures. Procalcitonin is a useful marker to rule out sepsis and systemic inflammation in the ED.

Prevalence of systemic inflammatory response syndrome (SIRS) in hospitalized children: a point prevalence study

BACKGROUND

In accordance with the 1st International pediatric sepsis consensus conference, where sepsis was defined as SIRS associated with suspected or proven infection, we have identified the need to assess the prevalence of SIRS and sepsis in children with abnormal temperatures hospitalized in The Children's Clinical University Hospital in Latvia.

METHODS

A descriptive prospective point prevalence study (using two time periods, each 24 h, randomly chosen) was conducted on all children (n = 943) treated in the hospital. All children with abnormal temperatures - fever or hypothermia (n = 92) - were included in the study. Questionnaires evaluating age-specific SIRS criteria were completed. The prevalence of SIRS was detected with 95% CI.

RESULTS

Out of a total of 943 patients treated in the hospital, 10% (n = 92) had abnormal temperatures. In all these cases the abnormal temperature was a fever; hypothermia was not established in any patient. Of the children with fever, 72% (n = 66) had SIRS. Of the SIRS patients, 8% (n = 5) developed sepsis, 5% (n = 3) severe sepsis and 2% (n = 1) septic shock. Seventy-six percent (n = 50) of the SIRS patients had fever in combination with respiratory rate >2 SD above normal for age; 50% (n = 33) had fever with abnormal leukocyte count; 15% (n = 10) had fever with tachycardia >2 SD above normal for age. Most of the SIRS patients (39%, n = 25) were aged 2-5 years. Twenty-one percent (n = 14) of the children with SIRS and 50% (n = 2) of those with severe sepsis and septic shock had an underlying disease. In no case was SIRS and sepsis recognized by doctors and the diagnoses were not recorded on the patients' cards.

CONCLUSION

Our results would indicate a high risk for sepsis development in children with SIRS. Early SIRS diagnosis and awareness of risk of developing sepsis could change the medical approach to the patient in everyday clinical practice, eventually leading to early, goal-directed therapy for sepsis.

Risk factors for increased mortality from hospital-acquired versus community-acquired infections in febrile medical patients

BACKGROUND

Risk factors for hospital-acquired infection and attributable mortality in surgical and critically ill patients are well-known. We sought to identify factors associated with increased mortality from hospital-acquired infections as compared with community-acquired infections in patients with new-onset fever and a presumed infectious focus (n = 212), in a department of internal medicine.

METHODS

Demographic, clinical, and laboratory variables were studied for 2 days after inclusion. Septic shock and outcome were monitored for up to 7 and 28 days after inclusion, respectively.

RESULTS

Of the 212 patients, 54 had hospital-acquired and 158 community-acquired infection, with septic shock rates of 15% and 4% and mortality rates of 24% and 6% (P = .001), respectively. Prior neurologic disease was associated with death. Patients with hospital-acquired infection had more often (intravascular) devices and underwent more often interventions, had a different distribution of infectious foci, and had more often bacteremia. Bacteremia-associated septic shock was associated with nonsurvival in both infection groups. The causative agents were not associated with outcome, and the clinical and laboratory host response associated with nonsurvival generally did not differ among infection groups.

CONCLUSION

Our data suggest that hospital-acquired infections carry a higher crude mortality rate than community-acquired infection in febrile medical patients, mainly because of more frequent use of devices and hospital interventions and resultant bacteremia and septic shock, rather than by differences in underlying diseases, causative agents, and clinical and laboratory host responses. The observations thus emphasize the continued importance of preventive measures on medical wards of our hospital and can be used for comparison with future studies.

Hospital and 1-year outcomes of septic syndromes in older people: a cohort study

PURPOSE

Our objective was to describe the relationship between sepsis syndrome mortality and cognitive and physical disability in elderly persons.

METHODS

A 1-year consecutive cohort study in clinical beds of a university hospital was performed. Variables were severity of sepsis syndrome, organ failure, functional status, age, sex, and positive cultures. Outcomes were in-hospital and 1-year mortalities.

RESULTS

The study included 137 patients (>70 years), both sexes. Data from 116 (84.5%) patients were obtainable at 1-year follow-up. Forty-eight (35%) patients presented with sepsis (11/137, 8%) or severe sepsis (37/137, 27%). In-hospital mortality was 15.3% (0% for sepsis and 21.8% if severe) and increased with organ failure (p <.0001). One-year mortality was 54.78% (63/116), mostly related to severe sepsis; predictors were severe organ failure (p <.0001), prior functional status (p =.0005), and Mini-Mental State Examination (p =.03). Prior functional status and organ failure were independent predictors.

CONCLUSIONS

In-hospital and 1-year mortality increased with septic syndrome severity, prior functional status, and organ failure.

The role of procalcitonin in a decision tree for prediction of bloodstream infection in febrile patients

Bloodstream infection (BSI) in febrile patients is associated with high mortality. Clinical and laboratory variables, such as procalcitonin (PCT), may predict BSI and help decision-making concerning empirical treatment. This study compared two models for prediction of BSI, and evaluated the role of PCT vs. clinical variables, collected daily in 300 consecutive febrile inpatients, for 48 h after onset of fever. Multiple logistic regression (MLR) and classification and regression tree (CART) models were compared for discriminatory power and diagnostic performance. BSI was present in 17% of cases. MLR identified the presence of intravascular devices, nadir albumin and thrombocyte counts, and peak temperature, respiratory rate and leukocyte counts, but not PCT, as independent predictors of BSI. In contrast, a peak PCT level of >2.45 ng/mL was the principal discriminator in the decision tree based on CART. The latter was more accurate (94%) than the model based on MLR (72%; p <0.01). Hence, the presence of BSI in febrile patients is predicted more accurately and by different variables, e.g., PCT, in CART analysis, as compared with MLR models. This underlines the value of PCT plus CART analysis in the diagnosis of a febrile patient.

Brief report: incidence, etiology, risk factors, and outcome of hospital-acquired fever: a systematic, evidence-based review

OBJECTIVES

Temperature is universally measured in the hospitalized patient, but the literature on hospital-acquired fever has not been systematically reviewed. This systematic review is intended to provide clinicians with an overview of the incidence, etiology, and outcome of hospital-acquired fever.

DATA SOURCES

We searched MEDLINE (1970 to 2005), EMBASE (1988 to 2004), and Web of Knowledge. References of all included articles were reviewed. Articles that focused on children, fever in the developing world, classic fever of unknown origin, or specialized patient populations were excluded.

REVIEW METHODS

Articles were reviewed independently by 2 authors before inclusion; a third author acted as arbiter.

RESULTS

Of over 1,000 studies reviewed, 7 met the criteria for inclusion. The incidence of hospital-acquired fever ranged from 2% to 17%. The etiology of fever was infection in 37% to 74%. Rates of antibiotic use for patients with a noninfectious cause of fever ranged from 29% to 55% for a mean duration of 6.6 to 9.6 days. Studies varied widely in their methodology and the patient population studied.

CONCLUSIONS

Limited information is available to guide an evidence-based approach to hospital-acquired fever. We propose criteria to help standardize future studies of this important clinical situation.

The CURB65 pneumonia severity score outperforms generic sepsis and early warning scores in predicting mortality in community-acquired pneumonia

BACKGROUND

The performance of CURB65 in predicting mortality in community-acquired pneumonia (CAP) has been tested in two large observational studies. However, it has not been tested against generic sepsis and early warning scores, which are increasingly being advocated for identification of high-risk patients in acute medical wards.

METHOD

A retrospective analysis was performed of data prospectively collected for a CAP quality improvement study. The ability to stratify mortality and performance characteristics (sensitivity, specificity, positive predictive value, negative predictive value and area under the receiver operating curve) were calculated for stratifications of CURB65, CRB65, the systemic inflammatory response syndrome (SIRS) criteria and the standardised early warning score (SEWS).

RESULTS

419 patients were included in the main analysis with a median age of 74 years (men = 47%). CURB65 and CRB65 stratified mortality in a more clinically useful way and had more favourable operating characteristics than SIRS or SEWS; for example, mortality in low-risk patients was 2% when defined by CURB65, but 9% when defined by SEWS and 11-17% when defined by variations of the SIRS criteria. The sensitivity, specificity, positive predictive value and negative predictive value of CURB65 was 71%, 69%, 35% and 91%, respectively, compared with 62%, 73%, 35% and 89% for the best performing version of SIRS and 52%, 67%, 27% and 86% for SEWS. CURB65 had the greatest area under the receiver operating curve (0.78 v 0.73 for CRB65, 0.68 for SIRS and 0.64 for SEWS).

CONCLUSIONS

CURB65 should not be supplanted by SIRS or SEWS for initial prognostic assessment in CAP. Further research to identify better generic prognostic tools is required.

Prevention and treatment of multiple organ dysfunction syndrome: lessons learned and future prospects

Gram-negative bacteria commonly cause serious infections in hospitalized patients, and those that lead to bacteremic episodes and sepsis syndrome are associated with the highest mortality rate. Sepsis syndrome frequently progresses to multisystem organ dysfunction and failure, with as many as 400,000 cases occurring annually. Unfortunately, the associated mortality rate remains about 40%. Lipopolysaccharide (LPS, endotoxin), an integral component of the gram-negative bacterial outer membrane, plays a critical role in the pathophysiology of this lethal disease process. It is capable of interacting with host macrophages, a process that leads to the secretion of an increasingly well-characterized array of macrophage cytokines. Several different classes of compounds that bind directly to LPS and thereby neutralize its effects are being examined. These consist of anti-LPS monoclonal antibodies (mAbs), naturally occurring proteins and their derivatives (e.g., bactericidal/permeability-increasing protein [BPI], Limulus anti-LPS factor [LALF]), and certain antibiotics (polymyxin B, taurolidine). The molecular biology of BPI, LALF, and LPS binding protein (LBP, which augments the host response to LPS) is of considerable interest, as each demonstrates considerable genetic sequence homology. Although two anti-LPS monoclonal antibodies (HA-1A, E5) did not demonstrate efficacy during sepsis syndrome, information obtained from these clinical trials provided investigators with the ability to better understand this disease process. However, a detailed understanding of the biology of endotoxin antagonism is beginning to emerge, and the application of this knowledge in the clinical setting provides hope that it may be possible to reduce the mortality of sepsis syndrome caused by these microorganisms to a statistic well below the current 40%.

Use of the Sequential Organ Failure Assessment score as a severity score

OBJECTIVE

To evaluate whether the SOFA score can be used to develop a model to predict intensive care unit (ICU) mortality in different countries.

DESIGN AND SETTING

Analysis of a prospectively collected database. Patients with ICU stay longer than 2 days were studied to develop a mortality prediction model based on measurements of organ dysfunction.

PATIENTS

748 patients from six countries.

MEASUREMENTS AND RESULTS

Two logistic regression models were constructed, one based on the SOFA maximum (SOFA Max model) and the other on variables identified by multivariate regression (SOFA Max-infection model). The H and C statistics had a p value above 0.05 for both models, but the D statistics showed a poor performance on the SOFA Max model when stratified for the presence of infection. Subsequent analysis was performed with SOFA Max-infection model. The area under the curve was 0.853. There were no statistically significant differences in observed and predicted mortalities except for one country which had a higher than predicted ICU mortality both in the overall population (28.3 vs. 19.1%) and in the noninfected patients (21.4 vs. 12.6%).

CONCLUSIONS

The SOFA Max adjusted for age and the presence of infection can predict mortality in this population, but in one country the ICU mortality was higher than expected. Our data do not allow us to determine the reasons behind these differences, and further studies to detect differences in mortality between countries and to elucidate the basis for these differences should be encouraged.

The involvement of hydroxyl radical and cyclooxygenase metabolites in the activation of lung vagal sensory receptors by circulatory endotoxin in rats

Circulatory endotoxin can stimulate vagal pulmonary C fibers and rapidly adapting receptors (RARs) in rats, but the underlying mechanisms are not clear. We investigated the involvement of hydroxyl radicals and cyclooxygenase metabolites in the stimulation of C fibers and RARs by circulatory endotoxin (50 mg/kg) in 112 anesthetized, paralyzed, and artificially ventilated rats. In rats pretreated with the vehicle, endotoxin stimulated C fibers and RARs and caused a slight increase in total lung resistance (Rl) and a decrease in dynamic lung compliance. In rats pretreated with dimethylthiourea (a hydroxyl radical scavenger) alone, indomethacin (a cyclooxygenase inhibitor) alone, or a combination of the two, C-fiber and RAR responses [C fiber: change (Delta) = -62, -79, and -85%; RAR: Delta = -80, -84, and -84%, respectively] were reduced, and the Rl response was prevented. The suppressive effects of a combination of dimethylthiourea and indomethacin on the C-fiber and RAR responses were not superior to indomethacin alone. In rats pretreated with isoproterenol (a bronchodilator), the C-fiber response was not significantly affected (Delta = -26%), the RAR response was reduced (Delta = -88%), and the Rl response was prevented. None of these pretreatments affected the dynamic lung compliance response. These results suggest that 1) both hydroxyl radicals and cyclooxygenase metabolites are involved in the endotoxin-induced stimulation of C fibers and RARs, and 2) the involvement of these two metabolites in the C-fiber stimulation may be due to their chemical effects, whereas that in the RAR stimulation may be due to their bronchoconstrictive effects.

The utilisation of continuous veno-venous haemofiltration for the removal of septic mediators in patients with systemic inflammatory response syndrome

Septic shock is the leading cause of morbidity and mortality in critically ill patients. If the mediators responsible for the continuum of the sepsis cascade could be blocked or removed, patient outcome might improve. Researchers have been attempting to eliminate such mediators by continuous veno-venous haemofiltration (CVVH) but, despite over a decade of studies, many obstacles still remain. In this article, a comparison has been made of four similar research studies to ascertain any significant findings. Future research proposals have been considered in conjunction with the role the nurse within critical care might play in what could arguably be considered to be within the medical domain.

Influence of systemic inflammatory response syndrome and sepsis on outcome of critically ill infected patients

The clinical significance of the systemic inflammatory response in infected patients remains unclear. We examined risk factors for hospital mortality in 3,608 intensive care unit patients included in the European Sepsis Study. Patients were categorized as having infection without or with (i.e., sepsis) systemic inflammatory response, severe sepsis, and septic shock, on the first day of infection. Hospital mortality varied from 25 to 60% according to sepsis stage, but did not differ between the first two categories (hazard ratio, 0.94; p = 0.55), whereas there was a grading of severity from sepsis to severe sepsis (1.53, p < 10-4) and septic shock (2.64, p < 10-4). Within each stage, mortality was unaffected by the number of inflammatory response criteria. Prognostic factors identified by Cox regression included comorbid conditions, severity of acute illness and acute organ dysfunction, shock, nosocomial infection, and infection caused by aerobic gram-negative bacilli, enterobacteria, Staphylococcus aureus, and infection from a digestive or unknown source. We conclude that whereas the categorization of infection by the presence of organ dysfunction or shock has strong prognostic significance, infection and sepsis have similar outcomes, unaffected by the presence or number of inflammatory response criteria. Refinement of risk stratification of patients presenting with infection and no organ dysfunction is needed.

The problems and challenges of immunotherapy in sepsis

Despite decades of research, the morbidity and mortality of sepsis and septic shock remain very high. To further compound the problem, results from all investigative trials (with one exception) have shown that tested immunotherapies aimed at modulating the excessive expression of key cytokines, such as the interleukins and tumor necrosis factor, have been either equivalent or inferior to placebo. While controversy prevails in terms of continuing such investigative trials, study designs can be held accountable for inherent flaws. Testing for the wrong hypothesis, errant study design, using the wrong agent, focusing on an inappropriate target group, excessive expectations, and uncontrolled variables have potentially obscured the real efficacy such agents might have to offer. By standardizing protocols and reducing uncontrolled variables, research can be more precisely targeted so as to unmask the real benefits to the patient.

Standardized immune monitoring for the prediction of infections after cardiopulmonary bypass surgery in risk patients

BACKGROUND

Infections are the most common cause of late complications in cardiopulmonary bypass (CPB) surgery patients, and are difficult to predict. Here we studied the diagnostic value of a standardized immune monitoring program based on recent advances in flow cytometry (exact quantification of surface-marker expression) and cytokine determination (semiautomatic systems).

METHODS

CPB patients (56) at risk for complications (age >70 years and/or preoperative left-ventricular ejection fraction < 25 %) were classified into three groups: without (33), with suspected (14), and with confirmed (9) infection. Applying the Quantibrite trade mark -system, we daily quantified the expression of CD11b, CD64, CD71, CD86, and HLA-DR on monocytes/granulocytes. Furthermore, the ex vivo secretion of tumor necrosis factor (TNF)-alpha as well as the plasma interleukin (IL)-10 levels were determined by a semiautomatic system. Ex vivo elastase release was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

All patients showed signs of granulocyte activation and monocyte deactivation. Monocytic HLA-DR and plasma IL-10 were the best markers to discriminate patients with infection from those without as early as day 1. Using a cutoff of 5792 HLA-DR molecules per cell, both sensitivity and negative predictive value for patients who developed microbiologically confirmed infection was 1.0, and the area under the curve (AUC) was 0.85.

CONCLUSIONS

Our data suggest that a standardized immune monitoring at day 1 might be useful for early discrimination of patients at elevated risk for infections.

Circulating inflammatory mediators predict shock and mortality in febrile patients with microbial infection

The host response to microbial infection is associated with the release of inflammatory mediators. We hypothesized that the type and degree of the systemic response as reflected by levels of circulating mediators predict morbidity and mortality, according to the invasiveness of microbial infection. We prospectively studied 133 medical patients with fever and culture-proven microbial infection. For 3 days after inclusion, the circulating levels of activated complement C3a, interleukin (IL)-6, and secretory phospholipase A(2) (sPLA(2)) were determined daily. Based on results of microbiological studies performed for up to 7 days, patients were classified as having local infections (Group 1, n = 80 positive local cultures or specific stains for fungal or tuberculous infections) or bacteremia (Group 2, n = 52 plus 1 patient with malaria parasitemia). Outcome was assessed as the development of septic shock and as mortality up to 28 days after inclusion. Fifteen patients (11%) developed septic shock and overall mortality was 18% (n = 24). Bacteremia was associated with shock and shock predisposed to death. Circulating mediator levels were generally higher in Group 2 than in Group 1. Circulating levels of IL-6 and sPLA(2) were higher in patients developing septic shock and in nonsurvivors, particularly in Group 1. High C3a was particularly associated with nonsurvival in Group 2. In Group 1, the area under the curve (AUC) of the receiver operating characteristic (ROC) curve for the peak sPLA(2) for shock development was 0.79 (P < 0.05). The AUC of the ROC curve of the peak IL-6 and sPLA(2) for mortality was 0.69 and 0.68 (P < 0.05), respectively. In Group 2, the AUC of the ROC for peak C3a predicting mortality was 0.73 (P < 0.05). In conclusion, in medical patients with fever and microbial infection, the systemic inflammatory host response predicts shock and death, at an early stage, dependent on the invasiveness of microbial infection. The results suggest a differential pathogenetic role of complement activation on the one hand and release of cytokine and lipid mediators on the other in bacteremic and local microbial infections, respectively. They may partly explain the failure of strategies blocking proinflammatory cytokines or sPLA(2) in human sepsis and may extend the basis for attempts to inhibit complement activation at an early stage in patients at risk of dying from invasive microbial infections.

Plasminogen activators in inflammation and sepsis

Mortality of severe sepsis remains at 40% to 50%. Intensive efforts over the past two decades have only marginally improved outcome. Improving outcome in sepsis depends on understanding its pathophysiology, which involves triggers, responses of the organism, and dysfunction. Stress, injury, or infection trigger host responses, including local and systemic orchestrated mechanisms. Dysfunction and outcome depend on both trigger and response. Blood coagulation, inflammation, immunity, and fibrinolysis are critical components of the organism's responses. Understanding their role in sepsis pathophysiology is the key to effective treatment. Relevant studies were identified by a systematic literature search, complemented by manual search of individual citations. Using PubMed, 'sepsis' yields more than 62,000 references, 'plasminogen activators' more than 21,000. The selection of citations was guided by preference for reviews that expand important threads of argumentation. Single original studies were included when relevant to critical points. This analytical review describes the essential elements of pathophysiology and the current status of sepsis treatment. Based on this context, an emerging therapeutic option will be discussed: plasminogen activators.

Back to basics: validation of the admission systemic inflammatory response syndrome score in predicting outcome in trauma

BACKGROUND

We have previously documented that the admission systemic inflammatory response syndrome (SIRS) score, calculated with four variables-temperature, heart rate, neutrophil count, and respiratory rate-is a significant predictor of outcome in trauma (n = 4,887). The objective of this current study was to validate our previous findings in a larger trauma patient population, to analyze the predictive accuracy of the four individual components of the SIRS score (temperature, heart rate, neutrophil count, and respiratory rate), and to assess whether the admission SIRS score is an accurate predictor of intensive care unit (ICU) resource use in trauma.

METHODS

Prospective data were collected on 9,539 patients admitted to a Level I trauma center over a 30-month period (January 1997-July 1999). Patients were stratified by age, sex, race, and Injury Severity Score (ISS). SIRS score was calculated at admission, and SIRS was defined as a SIRS score > or = 2.

RESULTS

SIRS score was validated as a significant independent predictor of outcome in trauma by logistic regression analysis after controlling for age and ISS. Of the four SIRS variables, hypothermia (temperature < 36 degrees C) was the most significant predictor of mortality after controlling for age and ISS. Leukocytosis (neutrophil count > 12,000/mm3) was the most significant predictor of total hospital length of stay. SIRS scores of > or = 2 were increasingly predictive of mortality and ICU admission by logistic regression analysis (p < 0.001).

CONCLUSION

These data provide further validation that an admission SIRS score of > or = 2 is a significant independent predictor of outcome and ICU resource use in trauma. Temperature (hypothermia) is the individual component of the SIRS score with the greatest predictive accuracy. SIRS score should be calculated on all trauma admissions.

Prediction of shock in febrile medical patients with a clinical infection

OBJECTIVE

Shock in the course of fever is likely caused by septic shock. Because septic shock carries a high mortality rate, early recognition could benefit the patient. We tried to predict the development of shock in medical patients with fever and a clinical infection, on the basis of clinical and microbiological information, and to evaluate the role therein of systemic inflammatory response syndrome (SIRS) criteria: abnormal body temperature, tachycardia, tachypnea, and abnormal white blood cell counts.

DESIGN

Prospective observational study.

SETTING

Department of Internal Medicine at a university hospital.

PATIENTS

Patients were 212 consecutive medical patients with newly onset fever (temperature, >38.0 degrees C axillary or >38.3 degrees C rectally) and a clinical source of infection.

MEASUREMENTS AND MAIN RESULTS

Of the 212 patients enrolled, 14 developed shock (i.e., a decrease in systolic arterial blood pressure of >40 mm Hg) during a maximum follow-up period of 7 days after inclusion. In univariate analyses, advanced age, prior urogenital disease, an abdominal source, nosocomial infections, and bacteremia predisposed patients to shock (p < .05). For clinical variables, obtained daily for 2 days after inclusion, a low performance (p < .001), the peak respiratory rate (p < .05), the peak heart rate (p < .05), the nadir score on the Glasgow Coma Scale (p < .005), the peak and nadir white blood cell counts (p < .005), and the nadir albumin (p < .01) and peak creatinine concentrations in blood (p < .001) predicted shock development. In multivariate analysis, the presence of bacteremia, the peak respiratory rate, the nadir Glasgow Coma Scale score, and the peak white blood cell count positively and the peak erythrocyte sedimentation rate negatively contributed to prediction of shock development. In contrast, SIRS had less predictive value, mainly because of lack of predictive value of peak heart rate and temperature in multivariate models.

CONCLUSION

In febrile medical patients with a clinical infection, the development of shock involves an interaction between circulating microbial products and the host response, which can be recognized clinically by variables easily obtained at the bedside and partly different from the set used to define SIRS.

The clinical host response to microbial infection in medical patients with fever

STUDY OBJECTIVES

Predictors among demographic, clinical, and laboratory variables for a microbial (nonviral/nonchlamydial) infection in hospitalized medical patients with new onset of fever (temperature > or =38.0 degrees C axillary or > or =38.3 degrees C rectal) were analyzed and compared with the criteria for the systemic inflammatory response syndrome (SIRS), including an abnormal body temperature and WBC count, tachypnea and tachycardia, and sepsis, defined as SIRS and the presence of a clinical infection.

DESIGN

A prospective cohort study.

SETTING

Department of internal medicine at a university hospital.

PATIENTS

In 300 hospitalized medical patients with new onset of fever, demographic, clinical, and laboratory variables were obtained during the first 2 days after inclusion, and peak and nadir values, when appropriate, were taken. Microbiologic results for 7 days were collected. Clinical information was used to decide on the presence of a clinical infection.

MEASUREMENTS AND RESULTS

One hundred thirty-three of 300 patients (44%) had a microbial infection: 26% suffered from local microbial infection only, 9% from bacteremia only, and 9% had bloodstream plus local microbial infections. Patients with a microbial infection had a higher World Health Organization performance score at home (p<0.05), higher peak body temperature (p<0.001), higher nadir and peak WBC counts (p<0.05), lower nadir platelet count (p<0.01), higher peak alanine and aspartate aminotransferases (p<0.01), and lower nadir albumin (p<0.001) levels in blood during the first 2 days after inclusion than those without infection. Using multivariate techniques, predictors for microbial infection or bacteremia alone, independent of age, sex, underlying disease, and clinical infection, were peak temperature, peak WBC count, and nadir platelet count and albumin level. In contrast, conventional SIRS/sepsis definitions and criteria predicted microbial infection less well, mainly because tachypnea and tachycardia were of no predictive value.

CONCLUSIONS

In febrile medical patients, microbial infection can be predicted with use of easily obtained clinical and laboratory variables, including peak temperature, peak WBC count, and nadir platelet count and albumin level within the first 2 days. The new model predicted microbial infection better than conventional SIRS/sepsis criteria. This may help to improve the clinical recognition of the systemic host response to microbial infection and to refine SIRS/sepsis definitions.