Glasgow Coma Scale score dominates the association between admission Sequential Organ Failure Assessment score and 30-day mortality in a mixed intensive care unit population

Association of Glasgow coma scale and endotracheal intubation in predicting mortality among patients admitted to the intensive care unit

BACKGROUND

We assessed predictors of mortality in the intensive care unit (ICU) and investigated if Glasgow coma scale (GCS) is associated with mortality in patients undergoing endotracheal intubation (EI).

METHODS

From February 2020, we performed a 1-year study on 2,055 adult patients admitted to the ICU of two teaching hospitals. The outcome was mortality during ICU stay and the predictors were patients' demographic, clinical, and laboratory features.

RESULTS

EI was associated with a decreased risk for mortality compared with similar patients (adjusted odds ratio [AOR], 0.32; P=0.030). This shows that EI had been performed correctly with proper indications. Increasing age (AOR, 1.04; P<0.001) or blood pressure (AOR, 1.01; P<0.001), respiratory problems (AOR, 3.24; P<0.001), nosocomial infection (AOR, 1.64; P=0.014), diabetes (AOR, 5.69; P<0.001), history of myocardial infarction (AOR, 2.52; P<0.001), chronic obstructive pulmonary disease (AOR, 3.93; P<0.001), immunosuppression (AOR, 3.15; P<0.001), and the use of anesthetics/sedatives/hypnotics for reasons other than EI (AOR, 4.60; P<0.001) were directly; and GCS (AOR, 0.84; P<0.001) was inversely related to mortality. In patients with trauma surgeries (AOR, 0.62; P=0.014) or other surgical categories (AOR, 0.61; P=0.024) undergoing EI, GCS had an inverse relation with mortality (accuracy=82.6%, area under the receiver operator characteristic curve=0.81).

CONCLUSIONS

A variety of features affected the risk for mortality in patients admitted to the ICU. Considering GCS score for EI had the potential of affecting prognosis in subgroups of patients such as those with trauma surgeries or other surgical categories.

Multicenter International Cohort Validation of a Modified Sequential Organ Failure Assessment Score Using the Richmond Agitation-sedation Scale

OBJECTIVE

In a multicenter, international cohort, we aimed to validate a modified Sequential Organ Failure Assessment (mSOFA) using the Richmond Agitation-Sedation Scale, hypothesized as comparable to the Glasgow Coma Scale (GCS)-based Sequential Organ Failure Assessment (SOFA).

SUMMARY BACKGROUND DATA

The SOFA score, whose neurologic component is based on the GCS, can predict intensive care unit (ICU) mortality. But, GCS is often missing in lieu of other assessments, such as the also reliable and validated Richmond Agitation Sedation Scale (RASS). Single-center data suggested an RASS-based SOFA (mSOFA) predicted ICU mortality.

METHODS

Our nested cohort within the prospective 2016 Fourth International Study of Mechanical Ventilation contains 4120 ventilated patients with daily RASS and GCS assessments (20,023 patient-days, 32 countries). We estimated GCS from RASS via a proportional odds model without adjustment. ICU mortality logistic regression models and c-statistics were constructed using SOFA (measured GCS) and mSOFA (measured RASS-estimated GCS), adjusted for age, sex, body-mass index, region (Europe, USA-Canada, Latin America, Africa, Asia, Australia-New Zealand), and postoperative status (medical/surgical).

RESULTS

Cohort-wide, the mean SOFA=9.4+/-2.8 and mean mSOFA = 10.0+/-2.3, with ICU mortality = 31%. Mean SOFA and mSOFA similarly predicted ICU mortality (SOFA: AUC = 0.784, 95% CI = 0.769-0.799; mSOFA: AUC = 0.778, 95% CI = 0.763-0.793, P = 0.139). Across models, other predictors of mortality included higher age, female sex, medical patient, and African region (all P < 0.001).

CONCLUSIONS

We present the first SOFA modification with RASS in a "real-world" international cohort. Estimating GCS from RASS preserves predictive validity of SOFA to predict ICU mortality. Alternative neurologic measurements like RASS can be viably integrated into severity of illness scoring systems like SOFA.

Establishment of ICU Mortality Risk Prediction Models with Machine Learning Algorithm Using MIMIC-IV Database

Objective: The mortality rate of critically ill patients in ICUs is relatively high. In order to evaluate patients’ mortality risk, different scoring systems are used to help clinicians assess prognosis in ICUs, such as the Acute Physiology and Chronic Health Evaluation III (APACHE III) and the Logistic Organ Dysfunction Score (LODS). In this research, we aimed to establish and compare multiple machine learning models with physiology subscores of APACHE III—namely, the Acute Physiology Score III (APS III)—and LODS scoring systems in order to obtain better performance for ICU mortality prediction. Methods: A total number of 67,748 patients from the Medical Information Database for Intensive Care (MIMIC-IV) were enrolled, including 7055 deceased patients, and the same number of surviving patients were selected by the random downsampling technique, for a total of 14,110 patients included in the study. The enrolled patients were randomly divided into a training dataset (n = 9877) and a validation dataset (n = 4233). Fivefold cross-validation and grid search procedures were used to find and evaluate the best hyperparameters in different machine learning models. Taking the subscores of LODS and the physiology subscores that are part of the APACHE III scoring systems as input variables, four machine learning methods of XGBoost, logistic regression, support vector machine, and decision tree were used to establish ICU mortality prediction models, with AUCs as metrics. AUCs, specificity, sensitivity, positive predictive value, negative predictive value, and calibration curves were used to find the best model. Results: For the prediction of mortality risk in ICU patients, the AUC of the XGBoost model was 0.918 (95%CI, 0.915–0.922), and the AUCs of logistic regression, SVM, and decision tree were 0.872 (95%CI, 0.867–0.877), 0.872 (95%CI, 0.867–0.877), and 0.852 (95%CI, 0.847–0.857), respectively. The calibration curves of logistic regression and support vector machine performed better than the other two models in the ranges 0–40% and 70%–100%, respectively, while XGBoost performed better in the range of 40–70%. Conclusions: The mortality risk of ICU patients can be better predicted by the characteristics of the Acute Physiology Score III and the Logistic Organ Dysfunction Score with XGBoost in terms of ROC curve, sensitivity, and specificity. The XGBoost model could assist clinicians in judging in-hospital outcome of critically ill patients, especially in patients with a more uncertain survival outcome.

Limits of the Glasgow Coma Scale When Assessing for Sepsis in Allogeneic Hematopoietic Cell Transplant Recipients

BACKGROUND

The well-documented association between acute mental status changes and sepsis development and progression makes acute mental status an attractive factor for sepsis screening tools. However, the usefulness of acute mental status within these criteria is limited to the frequency and accuracy of its capture. The Glasgow Coma Scale (GCS) score-the acute mental status indicator in many clinical sepsis criteria-is infrequently captured among allogeneic hematopoietic cell transplant recipients with suspected infections, and its ability to serve as an indicator of acute mental status among this high-risk population is unknown.

OBJECTIVE

We evaluated the GCS score as an indicator of acute mental status during the 24 hours after suspected infection onset among allogeneic hematopoietic cell transplant recipients.

METHODS

Using data from the first 100 days posttransplant for patients transplanted at a single center between September 2010 and July 2017, we evaluated the GCS score as an indicator of documented acute mental status during the 24 hours after suspected infection onset. From all inpatients with suspected infections, we randomly selected a cohort based on previously published estimates of GCS score frequency among hematopoietic cell transplant recipients with suspected infections and performed chart review to ascertain documentation of clinical acute mental status within the 24 hours after suspected infection onset.

RESULTS

A total of 773 patients had ≥1 suspected infections and experienced 1,655 suspected infections during follow-up-625 of which had an accompanying GCS score. Among the randomly selected cohort of 100 persons with suspected infection, 28 were accompanied with documented acute mental status, including 18 without a recorded GCS. In relation to documented acute mental status, the GCS had moderate to high sensitivity and high specificity.

DISCUSSION

These data indicate that, among allogeneic hematopoietic cell transplant recipients with suspected infections, the GCS scores are infrequently collected and have a moderate sensitivity. If sepsis screening tools inclusive of acute mental status changes are to be used, nursing teams need to increase measurement of GCS scores among high sepsis risk patients or identify a standard alternative indicator.

Factors Disrupting Melatonin Secretion Rhythms During Critical Illness

OBJECTIVES

The circadian system modulates many important physiologic processes, synchronizing tissue-specific functions throughout the body. We sought to characterize acute alterations of circadian rhythms in critically ill patients and to evaluate associations between brain dysfunction, systemic multiple organ dysfunction, environmental stimuli that entrain the circadian rhythm (zeitgebers), rest-activity rhythms, and the central circadian rhythm-controlled melatonin secretion profile.

DESIGN

Prospective study observing a cohort for 24-48 hours beginning within the first day of ICU admission.

SETTING

Multiple specialized ICUs within an academic medical center.

PATIENTS

Patients presenting from the community with acute onset of either intracerebral hemorrhage as a representative neurologic critical illness or sepsis as a representative systemic critical illness. Healthy control patients were studied in using modified constant routine in a clinical research unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Light, feeding, activity, medications, and other treatment exposures were evaluated along with validated measures of encephalopathy (Glasgow Coma Scale), multiple organ system function (Sequential Organ Failure Assessment score), and circadian rhythms (profiles of serum melatonin and its urinary metabolite 6-sulphatoxymelatonin). We studied 112 critically ill patients, including 53 with sepsis and 59 with intracerebral hemorrhage. Environmental exposures were abnormal, including light (dim), nutritional intake (reduced or absent and mistimed), and arousal stimuli (increased and mistimed). Melatonin amplitude and acrophase timing were generally preserved in awake patients but dampened and delayed with increasing encephalopathy severity. Melatonin hypersecretion was observed in patients exposed to catecholamine vasopressor infusions, but unaffected by sedatives. Change in vasopressor exposure was the only factor associated with changes in melatonin rhythms between days 1 and 2.

CONCLUSIONS

Encephalopathy severity and adrenergic agonist medication exposure were the primary factors contributing to abnormal melatonin rhythms. Improvements in encephalopathy and medical stabilization did not rapidly normalize rhythms. Urinary 6-sulphatoxymelatonin is not a reliable measure of the central circadian rhythm in critically ill patients.

The Feasibility and Validity of Objective and Patient-Reported Measurements of Cognition During Early Critical Illness Recovery

BACKGROUND

Cognitive outcomes are an important determinant of quality of life after critical illness, but methods to assess early cognitive impairment and cognition recovery are not established. The objective of this study was to assess the feasibility and validity of objective and patient-reported cognition assessments for generalized use during early recovery from critical illness.

METHODS

Patients presented from the community with acute onset of either intracerebral hemorrhage (ICH) or sepsis as representative neurologic and systemic critical illnesses. Early cognitive assessments comprised the Glasgow Coma Scale (GCS), three NIH Toolbox cognition measures (Flanker Inhibitory Control and Attention Test, List Sorting Working Memory Test and Pattern Comparison Processing Speed Test) and two Patient Reported Outcomes Measurement Information System (PROMIS) cognition measures (Cognition-General Concerns and Cognition-Abilities) performed seven days after intensive care unit discharge or at hospital discharge, whichever occurred first.

RESULTS

We enrolled 91 patients (53 with sepsis, 38 with ICH), and after attrition principally due to deaths, cognitive assessments were attempted in 73 cases. Median [interquartile range] Sequential Organ Failure Assessment scores for patients with sepsis was 7 [3, 11]. ICH cases included 13 lobar, 21 deep and 4 infratentorial hemorrhages with a median [IQR] ICH Score 2 [1, 2]. Patient-reported outcomes were successfully obtained in 42 (58% overall, 79% of sepsis and 34% of ICH) patients but scores were anomalously favorable (median 97th percentile compared to the general adult population). Analysis of the PROMIS item bank by four blinded, board-certified academic neurointensivists revealed a strong correlation between higher severity of reported symptoms and greater situational relevance of the items (ρ = 0.72, p = 0.002 correlation with expert item assessment), indicating poor construct validity in this population. NIH Toolbox tests were obtainable in only 9 (12%) patients, all of whom were unimpaired by GCS (score 15) and completed PROMIS assessments. Median scores were 5th percentile (interquartile range [2nd, 9th] percentile) and uncorrelated with self-reported symptoms. Shorter intensive care unit length of stay was associated with successful testing in both patients with ICH and sepsis, along with lower ICH Score in patients with ICH and absence of premorbid dementia in patients with sepsis (all p < 0.05).

CONCLUSIONS

Methods of objective and patient-reported cognitive testing that have been validated for use in patients with chronic medical and neurologic illness were infeasible or yielded invalid results among a general sample of patients in this study who were in early recovery from neurologic and systemic critical illness. Longer critical illness duration and worse neurocognitive impairments, whether chronic or acute, reduced testing feasibility.

Critical Medical Illness and the Nervous System

PURPOSE OF REVIEW

Nervous system tissues have high metabolic demands and other unique vulnerabilities that place them at high risk of injury in the context of critical medical illness. This article describes the neurologic complications that are commonly encountered in patients who are critically ill from medical diseases and presents strategies for their diagnosis, prevention, and treatment.

RECENT FINDINGS

Chronic neurologic disability is common after critical medical illness and is a major factor in the quality of life for survivors of critical illness. Studies that carefully assessed groups of patients with general critical illness have identified a substantial rate of covert seizures, brain infarcts, muscle wasting, peripheral nerve injuries, and other neurologic sequelae that are strong predictors of poor neurologic outcomes. As the population ages and intensive care survivorship increases, critical illness-related neurologic impairments represent a large and growing proportion of the overall burden of neurologic disease.

SUMMARY

Improving critical illness outcomes requires identifying and managing the underlying cause of comorbid neurologic symptoms.

Factors Disrupting Melatonin Secretion Rhythms During Critical Illness

OBJECTIVES

The circadian system modulates many important physiologic processes, synchronizing tissue-specific functions throughout the body. We sought to characterize acute alterations of circadian rhythms in critically ill patients and to evaluate associations between brain dysfunction, systemic multiple organ dysfunction, environmental stimuli that entrain the circadian rhythm (zeitgebers), rest-activity rhythms, and the central circadian rhythm-controlled melatonin secretion profile.

DESIGN

Prospective study observing a cohort for 24-48 hours beginning within the first day of ICU admission.

SETTING

Multiple specialized ICUs within an academic medical center.

PATIENTS

Patients presenting from the community with acute onset of either intracerebral hemorrhage as a representative neurologic critical illness or sepsis as a representative systemic critical illness. Healthy control patients were studied in using modified constant routine in a clinical research unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Light, feeding, activity, medications, and other treatment exposures were evaluated along with validated measures of encephalopathy (Glasgow Coma Scale), multiple organ system function (Sequential Organ Failure Assessment score), and circadian rhythms (profiles of serum melatonin and its urinary metabolite 6-sulphatoxymelatonin). We studied 112 critically ill patients, including 53 with sepsis and 59 with intracerebral hemorrhage. Environmental exposures were abnormal, including light (dim), nutritional intake (reduced or absent and mistimed), and arousal stimuli (increased and mistimed). Melatonin amplitude and acrophase timing were generally preserved in awake patients but dampened and delayed with increasing encephalopathy severity. Melatonin hypersecretion was observed in patients exposed to catecholamine vasopressor infusions, but unaffected by sedatives. Change in vasopressor exposure was the only factor associated with changes in melatonin rhythms between days 1 and 2.

CONCLUSIONS

Encephalopathy severity and adrenergic agonist medication exposure were the primary factors contributing to abnormal melatonin rhythms. Improvements in encephalopathy and medical stabilization did not rapidly normalize rhythms. Urinary 6-sulphatoxymelatonin is not a reliable measure of the central circadian rhythm in critically ill patients.

Early noncardiovascular organ failure and mortality in the cardiac intensive care unit

Background

Noncardiac organ failure has been associated with worse outcomes among a cardiac intensive care unit (CICU) population.

Hypothesis

We hypothesized that early organ failure based on the sequential organ failure assessment (SOFA) score would be associated with mortality in CICU patients.

Methods

Adult CICU patients from 2007 to 2015 were reviewed. Organ failure was defined as any SOFA organ subscore ≥3 on the first CICU day. Organ failure was evaluated as a predictor of hospital mortality and postdischarge survival after adjustment for illness severity and comorbidities.

Results

We included 10 004 patients with a mean age of 67 ± 15 years (37% female). Admission diagnoses included acute coronary syndrome in 43%, heart failure in 46%, cardiac arrest in 12%, and cardiogenic shock in 11%. Organ failure was present in 31%, including multiorgan failure in 12%. Hospital mortality was higher in patients with organ failure (22% vs 3%, adjusted OR 3.0, 95% CI 2.5‐3.7, P < .001). After adjustment, each failing organ system predicted twofold higher odds of hospital mortality (adjusted OR 1.9, 95% CI 1.1‐2.1, P < .001). Mortality risk was highest with cardiovascular, coagulation and liver failure. Among hospital survivors, organ failure was associated with higher adjusted postdischarge mortality risk (P < .001); multiorgan failure did not confer added long‐term mortality risk.

Conclusions

Early noncardiovascular organ failure, especially multiorgan failure, is associated with increased hospital mortality in CICU patients, and this risk continues after hospital discharge, emphasizing the need to promote early recognition of organ failure in CICU patients.

Describing organ dysfunction in the intensive care unit: a cohort study of 20,000 patients

BACKGROUND

Multiple organ dysfunction is a common cause of morbidity and mortality in intensive care units (ICUs). Original development of the Sequential Organ Failure Assessment (SOFA) score was not to predict outcome, but to describe temporal changes in organ dysfunction in critically ill patients. Organ dysfunction scoring may be a reasonable surrogate outcome in clinical trials but further exploration of the impact of case mix on the temporal sequence of organ dysfunction is required. Our aim was to compare temporal changes in SOFA scores between hospital survivors and non-survivors.

METHODS

We performed a population-based observational retrospective cohort study of critically ill patients admitted from January 1, 2004, to December 31, 2013, to 4 multisystem adult intensive care units (ICUs) in Calgary, Canada. The primary outcome was temporal changes in daily SOFA scores during the first 14 days of ICU admission. SOFA scores were modeled between hospital survivors and non-survivors using generalized estimating equations (GEE) and were also stratified by admission SOFA (≤ 11 versus > 11).

RESULTS

The cohort consisted of 20,007 patients with at least one SOFA score and was mostly male (58.2%) with a median age of 59 (interquartile range [IQR] 44-72). Median ICU length of stay was 3.5 (IQR 1.7-7.5) days. ICU and hospital mortality were 18.5% and 25.5%, respectively. Temporal change in SOFA scores varied by survival and admission SOFA score in a complicated relationship. Area under the receiver operating characteristic (ROC) curve using admission SOFA as a predictor of hospital mortality was 0.77. The hospital mortality rate was 5.6% for patients with an admission SOFA of 0-2 and 94.4% with an admission SOFA of 20-24. There was an approximately linear increase in hospital mortality for SOFA scores of 3-19 (range 8.7-84.7%).

CONCLUSIONS

Examining the clinical course of organ dysfunction in a large non-selective cohort of patients provides insight into the utility of SOFA. We have demonstrated that hospital outcome is associated with both admission SOFA and the temporal rate of change in SOFA after admission. It is necessary to further explore the impact of additional clinical factors on the clinical course of SOFA with large datasets.

Predictive value of individual Sequential Organ Failure Assessment sub-scores for mortality in the cardiac intensive care unit

Purpose

To determine the impact of Sequential Organ Failure Assessment (SOFA) organ sub-scores for hospital mortality risk stratification in a contemporary cardiac intensive care unit (CICU) population.

Materials and methods

Adult CICU admissions between January 1, 2007 and December 31, 2015 were reviewed. The SOFA score and organ sub-scores were calculated on CICU day 1; patients with missing SOFA sub-score data were excluded. Discrimination for hospital mortality was assessed using area under the receiver-operator characteristic curve (AUROC) values, followed by multivariable logistic regression.

Results

We included 1214 patients with complete SOFA sub-score data. The mean age was 67 ± 16 years (38% female); all-cause hospital mortality was 26%. Day 1 SOFA score predicted hospital mortality with an AUROC of 0.72. Each SOFA organ sub-score predicted hospital mortality (all p <0.01), with AUROC values of 0.53 to 0.67. On multivariable analysis, only the cardiovascular, central nervous system, renal and respiratory SOFA sub-scores were associated with hospital mortality (all p <0.01). A simplified SOFA score containing the cardiovascular, central nervous system and renal sub-scores had an AUROC of 0.72.

Conclusions

In CICU patients with complete SOFA sub-score data, risk stratification for hospital mortality is determined primarily by the cardiovascular, central nervous system, renal and respiratory SOFA sub-scores.

Sequential Organ Failure Assessment Component Score Prediction of In-hospital Mortality From Sepsis

OBJECTIVES

Early organ dysfunction in sepsis confers a high risk of in-hospital mortality, but the relative contribution of specific types of organ failure to overall mortality is unclear. The objective of this study was to assess the predictive ability of individual types of organ failure to in-hospital mortality or prolonged intensive care.

METHODS

Retrospective cohort study of adult emergency department patients with sepsis from October 1, 2013, to November 10, 2015. Multivariable regression was used to assess the odds ratios of individual organ failure types for the outcomes of in-hospital death (primary) and in-hospital death or ICU stay ≥ 3 days (secondary).

RESULTS

Of 2796 patients, 283 (10%) experienced in-hospital mortality, and 748 (27%) experienced in-hospital mortality or an ICU stay ≥ 3 days. The following components of Sequential Organ Failure Assessment (SOFA) score were most predictive of in-hospital mortality (descending order): coagulation (odds ratio [OR]: 1.60, 95% confidence interval [CI]: 1.32-1.93), hepatic (1.58, 95% CI: 1.32-1.90), respiratory (OR: 1.33, 95% CI: 1.21-1.47), neurologic (OR: 1.20, 95% CI: 1.07-1.35), renal (OR: 1.14, 95% CI: 1.02-1.27), and cardiovascular (OR: 1.13, 95% CI: 1.01-1.25). For mortality or ICU stay ≥3 days, the most predictive SOFA components were respiratory (OR: 1.97, 95% CI: 1.79-2.16), neurologic (OR: 1.72, 95% CI: 1.54-1.92), cardiovascular (OR: 1.38, 95% CI: 1.23-1.54), coagulation (OR: 1.31, 95% CI: 1.10-1.55), and renal (OR: 1.19, 95% CI: 1.08-1.30) while hepatic SOFA (OR: 1.16, 95% CI: 0.98-1.37) did not reach statistical significance (P = .092).

CONCLUSION

In this retrospective study, SOFA score components demonstrated varying predictive abilities for mortality in sepsis. Elevated coagulation or hepatic SOFA scores were most predictive of in-hospital death, while an elevated respiratory SOFA was most predictive of death or ICU stay >3 days.

The Association Between Sequential Organ Failure Assessment Scores and Mortality in Patients With Sepsis During the First Week: The JSEPTIC DIC Study

OBJECTIVE

Predicting prognosis is a complex process, particularly in patients with severe sepsis or septic shock. This study aimed to determine the relationship between the Sequential Organ Failure Assessment (SOFA) scores for individual organs during the first week of admission and the in-hospital mortality in patients with sepsis.

METHODS

This study was a post hoc evaluation of the Japan Septic Disseminated Intravascular Coagulation study and included patients admitted to 42 intensive care units in Japan for severe sepsis or septic shock, between January 2011 and December 2013. We assessed the relationship between the organ and total SOFA scores on days 1, 3, and 7 following admission and the in-hospital mortality using logistic regression analysis.

RESULTS

We evaluated 2732 patients and found the in-hospital mortality rate was 29.1%. The mean age of the patients (standard deviation) was 70.5 (14.1) years, and the major primary site of infection was the abdomen (33.6%). The central nervous system (CNS) SOFA score exhibited the strongest relationship with mortality on days 1 (adjusted odds ratio [aOR]: 1.49, 95% confidence interval [CI]: 1.40-1.59), 3 (aOR: 1.75, 95% CI: 1.62-1.89), and 7 (aOR: 1.93, 95% CI: 1.77-2.10). The coagulation SOFA scores showed a weak correlation with mortality on day 1, but a strong correlation with mortality on day 7 (aOR: 2.04, 95% CI: 1.87-2.24).

CONCLUSIONS

The CNS SOFA scores were associated with mortality in patients with severe sepsis on days 1, 3, and 7 following hospitalization. The coagulation SOFA score was associated with mortality on day 7. In clinical situations, the CNS SOFA scores during the acute phase and the CNS SOFA and coagulation SOFA scores during the subsequent phases should be evaluated in order to determine patient prognosis.

Association of left ventricular longitudinal strain with central venous oxygen saturation and serum lactate in patients with early severe sepsis and septic shock

INTRODUCTION

In septic shock, assessment of cardiac function often relies on invasive central venous oxygen saturation (ScvO2). Ventricular strain is a non-invasive method of assessing ventricular wall deformation and may be a sensitive marker of heart function. We hypothesized that it may have a relationship with ScvO2 and lactate.

METHODS

We prospectively performed transthoracic echocardiography in patients with severe sepsis or septic shock and measured (1) left ventricular longitudinal strain from a four-chamber view and (2) ScvO2. We excluded patients for whom image quality was inadequate or for whom ScvO2 values were unobtainable. We determined the association between strain and ScvO2 with logistic and linear regression, using covariates of mean arterial pressure, central venous pressure, and vasopressor dose. We determined the association between strain and lactate. We considered strain greater than -17% as abnormal and strain greater than -10% as severely abnormal.

RESULTS

We studied 89 patients, 68 of whom had interpretable images. Of these patients, 42 had measurable ScvO2. Sixty percent of patients had abnormal strain, and 16% had severely abnormal strain. Strain is associated with low ScvO2 (linear coefficient -1.05, p =0.006; odds ratio 1.23 for ScvO2 <60%, p =0.016). Patients with severely abnormal strain had significantly lower ScvO2 (56.1% vs. 67.5%, p <0.01) and higher lactate (2.7 vs. 1.9 mmol/dl, p =0.04) than those who did not. Strain was significantly different between patients, based on a threshold ScvO2 of 60% (-13.7% vs. -17.2%, p =0.01) but not at 70% (-15.0% vs. -18.2%, p =0.08).

CONCLUSIONS

Left ventricular strain is associated with low ScvO2 and hyperlactatemia. It may be a non-invasive surrogate for adequacy of oxygen delivery during early severe sepsis or septic shock.

Designing optimal mortality risk prediction scores that preserve clinical knowledge

Many in-hospital mortality risk prediction scores dichotomize predictive variables to simplify the score calculation. However, hard thresholding in these additive stepwise scores of the form "add x points if variable v is above/below threshold t" may lead to critical failures. In this paper, we seek to develop risk prediction scores that preserve clinical knowledge embedded in features and structure of the existing additive stepwise scores while addressing limitations caused by variable dichotomization. To this end, we propose a novel score structure that relies on a transformation of predictive variables by means of nonlinear logistic functions facilitating smooth differentiation between critical and normal values of the variables. We develop an optimization framework for inferring parameters of the logistic functions for a given patient population via cyclic block coordinate descent. The parameters may readily be updated as the patient population and standards of care evolve. We tested the proposed methodology on two populations: (1) brain trauma patients admitted to the intensive care unit of the Dell Children's Medical Center of Central Texas between 2007 and 2012, and (2) adult ICU patient data from the MIMIC II database. The results are compared with those obtained by the widely used PRISM III and SOFA scores. The prediction power of a score is evaluated using area under ROC curve, Youden's index, and precision-recall balance in a cross-validation study. The results demonstrate that the new framework enables significant performance improvements over PRISM III and SOFA in terms of all three criteria.

Phenotypic clusters within sepsis-associated multiple organ dysfunction syndrome

INTRODUCTION

Sepsis is a devastating condition that is generally treated as a single disease. Identification of meaningfully distinct clusters may improve research, treatment and prognostication among septic patients. We therefore sought to identify clusters among patients with severe sepsis or septic shock.

METHODS

We retrospectively studied all patients with severe sepsis or septic shock admitted directly from the emergency department to the intensive care units (ICUs) of three hospitals, 2006-2013. Using age and Sequential Organ Failure Assessment (SOFA) subscores, we defined clusters utilizing self-organizing maps, a method for representing multidimensional data in intuitive two-dimensional grids to facilitate cluster identification.

RESULTS

We identified 2533 patients with severe sepsis or septic shock. Overall mortality was 17 %, with a mean APACHE II score of 24, mean SOFA score of 8 and a mean ICU stay of 5.4 days. Four distinct clusters were identified; (1) shock with elevated creatinine, (2) minimal multi-organ dysfunction syndrome (MODS), (3) shock with hypoxemia and altered mental status, and (4) hepatic disease. Mortality (95 % confidence intervals) for these clusters was 11 (8-14), 12 (11-14), 28 (25-32), and 21 (16-26) %, respectively (p < 0.0001). Regression modeling demonstrated that the clusters differed in the association between clinical outcomes and predictors, including APACHE II score.

CONCLUSIONS

We identified four distinct clusters of MODS among patients with severe sepsis or septic shock. These clusters may reflect underlying pathophysiological differences and could potentially facilitate tailored treatments or directed research.