Cardiovascular biomarkers in the ICU

Mouse Organ-Specific Proteins and Functions

Organ-specific proteins (OSPs) possess great medical potential both in clinics and in biomedical research. Applications of them—such as alanine transaminase, aspartate transaminase, and troponins—in clinics have raised certain concerns of their organ specificity. The dynamics and diversity of protein expression in heterogeneous human populations are well known, yet their effects on OSPs are less addressed. Here, we used mice as a model and implemented a breadth study to examine the panorgan proteome for potential variations in organ specificity in different genetic backgrounds. Using reasonable resources, we generated panorgan proteomes of four in-bred mouse strains. The results revealed a large diversity that was more profound among OSPs than among proteomes overall. We defined a robustness score to quantify such variation and derived three sets of OSPs with different stringencies. In the meantime, we found that the enriched biological functions of OSPs are also organ-specific and are sensitive and useful to assess the quality of OSPs. We hope our breadth study can open doors to explore the molecular diversity and dynamics of organ specificity at the protein level.

Association between troponin-I levels and outcome in critically ill patients admitted to non-cardiac intensive care unit with high prevalence of cardiovascular risk factors

Background

The association of troponin-I levels and outcome in medical-surgical ICU patients has been studied before in populations with low to moderate prevalence of cardiovascular risk factors. The objective in this article is to examine the association of troponin-I levels with hospital mortality in patients with high prevalence of cardiovascular risk factors who were admitted with medical-surgical indications to a non-cardiac intensive care unit.

Methods

This was a retrospective study of adult patients admitted to a tertiary medical-surgical ICU between July 2001 and November 2011. Data were extracted from prospectively collected ICU and clinical laboratory databases. Patients were stratified based on the highest troponin-I level in the first 72 h of admission into four groups (Group I < 0.03, Group II = 0.03–0.3, Group III = 0.3–3 and Group IV > 3 ng/mL). Hospital mortality was the primary outcome. To study the association between elevated troponin-I and hospital mortality, we carried out multivariate logistic regression analyses with Group I as a reference group.

Results

During the study period, 3368 patients had troponin-I levels measured in the first 72 h, of whom 1293 (38.3%) were diabetic and 1356 (40.2%) were chronically hypertensive. Among the study population, 2719 (81%) had elevated troponin-I levels (0.03 ng/mL and higher). Hospital mortality increased steadily as the troponin-I levels increased. Hospital mortality was 23.4% for Group I, 33.2% for Group II (adjusted odds ratio (aOR) 1.08, 95% confidence interval (CI) 0.84, 1.38), 49.6% for Group III (aOR = 1.64, 95% CI 1.24, 2.17), and 57.4% for Group IV (aOR 1.80, 95% CI 1.30, 2.49). The association of increased mortality with increased troponin level was observed whether patients had underlying advanced heart failure or not. Subgroup analysis showed an increased mortality in patients aged < 50 years, non-diabetics and not on vasopressors.

Conclusion

In a population with high prevalence of diabetes and hypertension, elevated troponin-I was frequently observed in medical-surgical critically ill patients, and showed a level-dependent association with hospital mortality.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0515-7) contains supplementary material, which is available to authorized users.

Persistently elevated osteopontin serum levels predict mortality in critically ill patients

Introduction

Inflammatory, autoimmune and metabolic disorders have been associated with alterations in osteopontin (OPN) serum levels. Furthermore, elevated serum levels of OPN were reported from a small cohort of patients with sepsis. We therefore analyzed OPN serum concentrations in a large cohort of critically ill medical patients.

Methods

A total of 159 patients (114 with sepsis, 45 without sepsis) were studied prospectively upon admission to the medical intensive care unit (ICU) as well as after 3 days of ICU treatment and compared to 50 healthy controls. Clinical data, various laboratory parameters as well as investigational inflammatory cytokine profiles were assessed. Patients were followed for approximately 1 year.

Results

We found significantly elevated serum levels of OPN at admission to the ICU and after 3 days of treatment in critically ill patients compared to healthy controls. OPN concentrations were related to disease severity and significantly correlated with established prognosis scores and classical as well as experimental markers of inflammation and multi-organ failure. In the total cohort, OPN levels decreased from admission to day 3 of ICU treatment. However, persistently elevated OPN levels at day 3 of ICU treatment were a strong independent predictor for an unfavorable prognosis, with similar or better diagnostic accuracy than routinely used markers of organ failure or prognostic scoring systems such as SAPS2 or APACHE II score.

Conclusions

Persistently elevated OPN serum concentrations are associated with an unfavourable outcome in patients with critical illness, independent of the presence of sepsis. Besides a possible pathogenic role of OPN in critical illness, our study indicates a potential value for OPN as a prognostic biomarker in critically ill patients during the early course of ICU treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0988-4) contains supplementary material, which is available to authorized users.

The rise and fall of NGAL in acute kidney injury

For many years, neutrophil gelatinase-associated lipocalin (NGAL) has been considered the most promising biomarker of acute kidney injury (AKI). Commercial assays and point-of-care instruments, now available in many hospitals, allow rapid NGAL measurements intended to guide the clinician in the management of patients with or at risk of AKI. However, these assays likely measure a mixture of different NGAL forms originating from different tissues. Systemic inflammation, commonly seen in critically ill patients, and several comorbidities contribute to the release of NGAL from haematopoietic and non-haematopoietic cells. The unpredictable release and complex nature of the molecule and the inability to specifically measure NGAL released by tubular cells have hampered its use a specific marker of AKI in heterogeneous critically ill populations. In this review, we describe the nature and cellular sources of NGAL, its biological role and diagnostic ability in AKI and the increasing concerns surrounding its diagnostic and clinical value.

Correlation of the oxygen radical activity and antioxidants and severity in critically ill surgical patients - study protocol

Background

Surgical patients who require an emergent operation commonly have severe sepsis or septic shock, followed by high morbidity and mortality rates.

Despite advances in treatment however, no predictable markers are available. In severe sepsis, many pathophysiologic mechanisms are involved in progression to organ failure, and oxygen free radical and antioxidants are known to contribute to this process. Oxygen free radical and antioxidants contribute to progression of organ failure in severe sepsis. In fact, oxygen radical activity has been reported to be correlated with disease severity and prognosis in patients with severe sepsis or septic shock. Accordingly, we aim to assess the usefulness of oxygen free radical and antioxidant concentrations to predict the disease severity and mortality in a cohort of critically ill surgical patients.

Methods/Design

This is a prospective observation study including patient demographic characteristics, clinical information, blood sampling/serum oxygen radical activity, serum antioxidant activity, serum antioxidant concentrations (zinc, selenium and glutamate), disease severity scores, outcomes, lengths of stay in intensive care unit, hospital 30-day mortality.

[Cardiac biomarkers in the critically ill]

Cardiac biomarkers in intensive care medicine are an excellent complement to existing clinical and diagnostic information in specific diseases. Due to their lack of specificity, the diagnostic properties of common cardiac biomarkers, such as natriuretic peptides and cardiac troponins, remain ambiguous, while their prognostic value has already been proven. In addition, there are several promising new biomarkers that might contribute to a "multimarker strategy" in the critically ill patient in the future, but further evaluation is still required.

Cardiac biomarkers in the critically ill

Cardiac biomarkers have well-established roles in acute coronary syndrome and congestive heart failure. In many instances, the detection of cardiac biomarkers may aid in the diagnosis and risk assessment of critically ill patients. Despite increasing interest in the use of cardiac biomarkers in noncardiac critical illness, no clear consensus exists on how and in which settings markers should be measured. This article briefly describes what constitutes an ideal biomarker and focuses on those that have been most well studied in critical illness, specifically troponin, the natriuretic peptides, and heart-type fatty acid-binding protein.

Brain natriuretic peptide measurement in pulmonary medicine

Serum levels of natriuretic peptides are well established as important biomarkers in patients with cardiac disease. Less attention has been placed on the role of natriuretic peptides in patients with pulmonary conditions. In several well-defined groups of patients with pulmonary disease natriuretic peptides provide the clinician with clinically valuable information. A limitation of the interpretation of natriuretic peptides in pulmonary disease is the confounding effect of concurrent conditions such as heart failure, hypoxia, sepsis and renal failure. The present paper reviews the role of natriuretic peptides for diagnosis, risk stratification and prognosis of several pulmonary disorders.

Systems biology in critical-care nursing

Systems biology applies advances in technology and new fields of study including genomics, transcriptomics, proteomics, and metabolomics to the development of new treatments and approaches of care for the critically ill and injured patient. An understanding of systems biology enhances a nurse's ability to implement evidence-based practice and to educate patients and families on novel testing and therapies. Systems biology is an integrated and holistic view of humans in relationship with the environment. Biomarkers are used to measure the presence and severity of disease and are rapidly expanding in systems biology endeavors. A systems biology approach using predictive, preventive, and participatory involvement is being utilized in a plethora of conditions of critical illness and injury including sepsis, cancer, pulmonary disease, and traumatic injuries.

Can plasma B-type natriuretic peptide levels predict need for mechanical ventilation after injury?

BACKGROUND

B-type natriuretic peptide (BNP) is a neurohormone released from cardiomyocytes in response to volume expansion and increased ventricular wall distension. Increased plasma BNP levels are associated with mortality in critically ill patients cared for in medical intensive care units (ICUs). Additionally, plasma BNP levels may serve as a biomarker for excessive fluid resuscitation after injury. The utility of plasma BNP levels as a prognosticator of outcomes after injury has not been previously described. The purpose of this study was to describe the change in plasma BNP levels over the first 48 hours after injury and determine if there was a correlation between plasma BNP levels and clinical outcomes.

METHODS

In this prospective observational cohort trial, plasma BNP levels were followed in injured patients admitted to a surgical ICU. Levels were obtained at admission to the emergency room (baseline) and at 12, 24, and 48 hours. Change in plasma BNP levels from baseline were calculated for each time point (ΔBNP). Demographic information was collected, including age, gender, injury severity score, ventilator days, ICU length of stay (LOS), hospital LOS, net fluid balance at 24 hours, and in-hospital mortality. Spearman's rank-order correlation coefficients were determined for plasma ΔBNP levels and outcome measures (days ventilated, ICU LOS, hospital LOS, and mortality).

RESULTS

Forty-four ICU patients were prospectively enrolled. Thirty-six patients (82%) were male, and 30 patients (68%) required mechanical ventilation. The mean age was 40.3 years. The median injury severity score was 19.5 (range, 9-29), and overall mortality was 14%. The mean baseline BNP level was 48 ± 66 pg/mL (range, 10-274 pg/mL). Mean ΔBNP at 24 hours was 74 ± 147 pg/mL. Net fluid balance at 48 hours after admission ranged from -1.6 to 15.6 L. Plasma ΔBNP levels at 24 and 48 hours did not correlate with net resuscitation volume at their respective time points of 24 and 48 hours. ΔBNP at 24 hours correlated with the number of days on mechanical ventilation (Spearman's ρ = .428, P = .007). ΔBNP at 24 hours also correlated with Acute Physiology and Chronic Health Evaluation II scores (Spearman's ρ = .430, P = .046). Patients with increases in plasma BNP of ≥ 75 pg/mL at 24 hours were nearly 3 times more likely to be ventilated for > 3 days (relative risk, 2.9; 95% confidence interval, 1.1-7.7).

CONCLUSIONS

Changes in plasma BNP levels over the first 24 hours after ICU admission may have prognostic value in determining the need for mechanical ventilation in patients admitted to ICUs after injury. Additionally, the correlation between plasma BNP levels at 24 hours and mechanical ventilation requirements is not due solely to resuscitation volume. Further studies examining the prognostic value of plasma BNP levels after injury are warranted.