EARLY FLUID RESUSCITATION IN SEPSIS: EVIDENCE AND PERSPECTIVES

Endothelial dysfunction triggers acute respiratory distress syndrome in patients with sepsis: a narrative review

Acute respiratory distress syndrome (ARDS) is a severe organ failure occurring mainly in critically ill patients as a result of different types of insults such as sepsis, trauma or aspiration. Sepsis is the main cause of ARDS, and it contributes to a high mortality and resources consumption both in hospital setting and in the community. ARDS develops mainly an acute respiratory failure with severe and often refractory hypoxemia. ARDS also has long term implications and sequelae. Endothelial damage plays an important role in the pathogenesis of ARDS. Understanding the mechanisms of ARDS presents opportunities for novel diagnostic and therapeutic targets. Biochemical signals can be used in concert to identify and classify patients into ARDS phenotypes allowing earlier effective treatment with personalised therapies. This is a narrative review where we aimed to flesh out the pathogenetic mechanisms and heterogeneity of ARDS. We examine the links between endothelium damage and its contribution to organ failure. We have also investigated future strategies for treatment with a special emphasis in endothelial damage.

Endothelial Damage and the Microcirculation in Critical Illness

Endothelial integrity maintains microcirculatory flow and tissue oxygen delivery. The endothelial glycocalyx is involved in cell signalling, coagulation and inflammation. Our ability to treat critically ill and septic patients effectively is determined by understanding the underpinning biological mechanisms. Many mechanisms govern the development of sepsis and many large trials for new treatments have failed to show a benefit. Endothelial dysfunction is possibly one of these biological mechanisms. Glycocalyx damage is measured biochemically. Novel microscopy techniques now mean the glycocalyx can be indirectly visualised, using sidestream dark field imaging. How the clinical visualisation of microcirculation changes relate to biochemical laboratory measurements of glycocalyx damage is not clear. This article reviews the evidence for a relationship between clinically evaluable microcirculation and biological signal of glycocalyx disruption in various diseases in ICU. Microcirculation changes relate to biochemical evidence of glycocalyx damage in some disease states, but results are highly variable. Better understanding and larger studies of this relationship could improve phenotyping and personalised medicine in the future. Damage to the glycocalyx could underpin many critical illness pathologies and having real-time information on the glycocalyx and microcirculation in the future could improve patient stratification, diagnosis and treatment.

Comparison of fluid resuscitation weight-based dosing strategies in obese patients with severe sepsis

OBJECTIVE

This study aims to compare the composite outcome of progression to septic shock between 30 mL/kg/ideal body weight (IBW) versus 30 mL/kg/non-IBW fluid resuscitation dosing strategies in obese patients with severe sepsis.

METHODS

We retrospectively evaluated obese patients admitted to an academic tertiary care center for the management of severe sepsis. Patients were included if they had a fluid bolus order placed using the sepsis order set between Oct 2018 and Sept 2019. The primary objective was the composite of progression to septic shock, defined as either persistent hypotension within 3 h after the conclusion of the 30 mL/kg fluid bolus administration or the initiation of vasopressor(s) within 6 h of the bolus administration.

RESULTS

Of 72 included patients, 49 (68%) were resuscitated using an IBW-based and 23 (32%) using a non-IBW-based dosing strategy. There were similar rates of progression to septic shock in the IBW and non-IBW groups (18% vs. 26%; p = 0.54). Median ICU and hospital LOS in the IBW group versus non-IBW group were (0 [IQR 0] vs. 0 [IQR 0 to 4] days; p = 0.13) and (6 [IQR 3 to 10] vs. 8 [IQR 5 to 12] days; p = 0.07), respectively. In-hospital mortality rates were similar between the groups.

CONCLUSIONS

Our study results suggest that in obese septic patients, fluid administration using an IBW-dosing strategy did not affect the progression to septic shock.

Septic shock in the ER: diagnostic and management challenges

Sepsis is a common presentation in the emergency department and a common cause of intensive care unit admissions and death. Accurate triage, rapid recognition, early resuscitation, early antibiotics, and eradication of the source of infection are the key components in delivering quality sepsis care. Evaluation of the patient's volume status, optimal hemodynamic resuscitation, and evaluation of patient response is crucial for sepsis management in the emergency department.

Cardiac Index Changes With Fluid Bolus Therapy in Children With Sepsis-An Observational Study

OBJECTIVES

Fluid bolus therapy is the initial recommended treatment for acute circulatory failure in sepsis, yet it is unknown whether this has the intended effect of increasing cardiac index. We aimed to describe the effect of fluid bolus therapy on cardiac index in children with sepsis.

DESIGN

A prospective observational cohort study.

SETTING

The Emergency Department of The Royal Children's Hospital, Melbourne, VIC, Australia.

PATIENTS

A convenience sample of children meeting international consensus criteria for sepsis with acute circulatory failure.

INTERVENTION

Treating clinician decision to administer fluid bolus therapy.

MEASUREMENTS AND MAIN RESULTS

Transthoracic echocardiography was recorded immediately before, 5 minutes after, and 60 minutes after fluid bolus therapy. Cardiac index was calculated by a pediatric cardiologist blinded to the timing of the echocardiogram. Cardiac index was calculated for 49 fluid boluses in 41 children. The median change in cardiac index 5 minutes after a fluid bolus therapy was +18.0% (interquartile range, 8.6-28.1%) and after 60 minutes was -6.0% (interquartile range, -15.2% to 3.0%) relative to baseline. Thirty-one of 49 fluid boluses (63%) resulted in an increase in cardiac index of greater than 10% at 5 minutes, and these participants were considered fluid responsive. This was sustained in four of 31 (14%) at 60 minutes. No association between change in cardiac index at 5 or 60 minutes and age, baseline mean arterial blood pressure, fluid bolus volume, and prior volume of fluid bolus therapy was found on linear regression.

CONCLUSIONS

Fluid bolus therapy for pediatric sepsis is associated with a transient increase in cardiac index. Fluid responsiveness is variable and, when present, not sustained. The efficacy of fluid bolus therapy for achieving a sustained increase in cardiac index in children with sepsis is limited.

Pharmacologic studies on ET-26 hydrochloride in a rat model of lipopolysaccharide-induced sepsis

BACKGROUND

ET-26 hydrochloride (ET-26 HCl) is a promising sedation-hypnotic compound with stable hemodynamic features that elicits virtually no adrenocortical suppression. However, whether it preserves better pharmacologic characteristics in a rat model of sepsis is not known. This study compared the survival rate, levels of corticosterone and pro-inflammatory cytokines, and histologic injury in the lungs and kidneys of rats suffering from sepsis treated with ET-26 HCl, etomidate, or normal saline (NS).

METHODS

Rats were given lipopolysaccharide (1mg/kg body weight, i.v.) to establish a sepsis model. Thirty minutes after lipopolysaccharide administration, ET-26 HCl, etomidate or NS were given as a bolus injection at equivalent doses. Plasma levels of corticosterone, interleukin-1β, interleukin-6, interleukin-10, and tumor necrosis factor-α were measured 1, 2, 4, 6 and 24h after administration. Histologic injury was observed at the time of death or 24h after drug administration.

RESULTS

The survival rate for rats in the etomidate, ET-26 HCl and NS groups was 40%, 90% and 90%, respectively. Corticosterone concentrations in the etomidate group were lower than those in the other groups 1h after administration of hypnotic compounds. Concentrations of pro-inflammatory cytokines in the ET-26 HCl group and NS group were not significantly different, but were significantly lower than those in the etomidate group. The injury scores of kidneys and lungs in the etomidate group were higher than those in ET-26 HCl and NS groups.

CONCLUSIONS

ET-26 HCl showed virtually no suppression of corticosterone synthesis, lower concentrations of pro-inflammatory cytokines, higher survival rate, and less organ injury in rats suffering from sepsis compared with the etomidate group. It may be safer to induce anesthesia using ET-26 HCl, rather than etomidate, in patients suffering from sepsis.

Shock in the first 24 h of intensive care unit stay: observational study of protocol-based fluid management

Precision in fluid management for shock could lead to better clinical outcomes. We evaluated the association of protocol-based fluid management with intensive care unit (ICU) and hospital mortality. We performed an observational study of mechanically ventilated patients admitted directly from our emergency department to the ICU from August 2011 to December 2013, who had circulatory shock in the first 24 h of ICU stay (systolic blood pressure <90 mmHg at ICU admission or lactate >4 mmol/L). Patients with onset of shock beyond 24 h of ICU stay were excluded. Protocol-based fluid management required close physician-nurse cooperation and computerized documentation, checking for fluid response (≥10% arterial pulse pressure or stroke volume increase after two consecutive 250-mL crystalloid boluses), and fluid loading with repeated 500-mL boluses until fluid response became negative. Six hundred twelve mechanically ventilated patients with shock (mean [±SD] age, 63.0 years [16.5]; 252 or 41.2% females; mean Acute Physiology and Chronic Health Evaluation II score, 30.2 [8.8]) were studied. The fluid management protocol was used 455 times for 242 patients (39.5% of 612 patients) within the first 24 h of ICU stay, with 244 (53.6% of 455) positive responses. Adjusted for age, sex, Acute Physiology and Chronic Health Evaluation II score, comorbidity, and admission year, protocol use was associated with reduced ICU mortality (odds ratio, 0.60; 95% confidence interval, 0.39-0.94; P = 0.025) but not hospital mortality (odds ratio, 0.82; 95% confidence interval, 0.54-1.23; P = 0.369). Among mechanically ventilated patients with shock within the first 24 h of ICU stay, about half had positive fluid responses. Adherence to protocol-based fluid management was associated with improved ICU survival.

Derivation and Validation of Predictive Factors for Clinical Deterioration after Admission in Emergency Department Patients Presenting with Abnormal Vital Signs Without Shock

INTRODUCTION

Strategies to identify high-risk emergency department (ED) patients often use markedly abnormal vital signs and serum lactate levels. Risk stratifying such patients without using the presence of shock is challenging. The objective of the study is to identify independent predictors of in-hospital adverse outcomes in ED patients with abnormal vital signs or lactate levels, but who are not in shock.

METHODS

We performed a prospective observational study of patients with abnormal vital signs or lactate level defined as heart rate ≥130 beats/min, respiratory rate ≥24 breaths/min, shock index ≥1, systolic blood pressure <90 mm/Hg, or lactate ≥4 mmole/L. We excluded patients with isolated atrial tachycardia, seizure, intoxication, psychiatric agitation, or tachycardia due to pain (ie: extremity fracture). The primary outcome was deterioration, defined as development of acute renal failure (creatinine 2× baseline), non-elective intubation, vasopressor requirement, or mortality. Independent predictors of deterioration after hospitalization were determined using logistic regression.

RESULTS

Of 1,152 consecutive patients identified with abnormal vital signs or lactate level, 620 were excluded, leaving 532 for analysis. Of these, 53/532 (9.9±2.5%) deteriorated after hospital admission. Independent predictors of in-hospital deterioration were: lactate >4.0 mmol/L (OR 5.1, 95% CI [2.1-12.2]), age ≥80 yrs (OR 1.9, CI [1.0-3.7]), bicarbonate <21 mEq/L (OR 2.5, CI [1.3-4.9]), and initial HR≥130 (OR 3.1, CI [1.5-6.1]).

CONCLUSION

Patients exhibiting abnormal vital signs or elevated lactate levels without shock had significant rates of deterioration after hospitalization. ED clinical data predicted patients who suffered adverse outcomes with reasonable reliability.

Measurement of plasma sTREM-1 in patients with severe sepsis receiving early goal-directed therapy and evaluation of its usefulness

The plasma level of soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) has been shown to be helpful in identifying critically ill patients with infection. However, it remains unknown whether it can be used to predict prognosis in patients with severe sepsis. This study investigated whether various inflammatory mediators, including sTREM-1, could be used as reliable markers to predict the prognosis of patients receiving early goal-directed therapy (EGDT). We prospectively enrolled patients 18 years or older with severe sepsis from April 2009 to May 2010 at a 2,000-bed university hospital. Patients were eligible if the initial resuscitation according to EGDT protocol was immediately performed at the emergency department. Plasma sTREM-1, C-reactive protein, and procalcitonin concentrations were measured on days 0, 3, 7, and 14. Soluble TREM-1 concentrations were significantly higher at admission and pre-EGDT in nonsurvivors (n = 16) than in survivors (n = 47) (514.1 pg/mL [interquartile range, 412.7-1,749.5 pg/mL] vs. 182.4 pg/mL [interquartile range, 54.3-327.0 pg/mL]; P = 0.001). Procalcitonin and C-reactive protein levels did not significantly differ, whereas central venous oxygen saturation and lactate levels at admission were significantly different between the two groups. The only sTREM-1 level remained significantly higher in nonsurvivors until death. On multivariate regression analysis, log(sTREM-1) (P = 0.028), central venous oxygen saturation (P = 0.022), and Simplified Acute Physiology Score II (P = 0.048) values at admission were independently significant. These results suggest that plasma sTREM-1 level at admission could be used as a marker to identify patients with a poor prognosis despite complete initial resuscitation in severe sepsis.

Late compliance with the sepsis resuscitation bundle: impact on mortality

Early compliance with the sepsis resuscitation bundle has been suggested to reduce mortality. However, few data are available about the impact of late compliance with the bundle on outcomes. The aim of this study was to assess whether the completion of the resuscitation bundle within the first 6 h after admission to the intensive care unit (ICU), but beyond the specific time limit of the various bundle interventions, is related to an improvement in survival. This prospective, cohort study included 753 patients recruited from September 2005 until August 2010 with severe sepsis/septic shock in the three medical-surgical ICUs of a tertiary academic medical center. We assessed the compliance with the different tasks included in the resuscitation bundle. Furthermore, we ascertained within the first 6 h after ICU admission the compliance with those tasks not carried out within their specific time limits; we have termed this variable "bundle improvement in the ICU." Septic shock was present in 88.1%. The overall in-hospital mortality was 31.6%. In 51.5%, there was bundle improvement in the ICU; this variable was associated with a lower risk of mortality (adjusted hazard ratio, 0.52 [95% confidence interval, 0.34-0.78]). That association was observed only when the time from severe sepsis onset to ICU admission was 6 h or less. Importantly, similar results were found after excluding all patients with severe sepsis (rapid responders) and those with refractory shock (nonresponders). The task with highest improvement was the achievement of central venous oxygen saturation 70% or greater in 39% of patients. Compliance with the resuscitation bundle even beyond the recommended time is associated with improvement in survival in patients with severe sepsis/septic shock.

Age of blood and recipient factors determine the severity of transfusion-related acute lung injury (TRALI)

Introduction

Critical care patients frequently receive blood transfusions. Some reports show an association between aged or stored blood and increased morbidity and mortality, including the development of transfusion-related acute lung injury (TRALI). However, the existence of conflicting data endorses the need for research to either reject this association, or to confirm it and elucidate the underlying mechanisms.

Methods

Twenty-eight sheep were randomised into two groups, receiving saline or lipopolysaccharide (LPS). Sheep were further randomised to also receive transfusion of pooled and heat-inactivated supernatant from fresh (Day 1) or stored (Day 42) non-leucoreduced human packed red blood cells (PRBC) or an infusion of saline. TRALI was defined by hypoxaemia during or within two hours of transfusion and histological evidence of pulmonary oedema. Regression modelling compared physiology between groups, and to a previous study, using stored platelet concentrates (PLT). Samples of the transfused blood products also underwent cytokine array and biochemical analyses, and their neutrophil priming ability was measured in vitro.

Results

TRALI did not develop in sheep that first received saline-infusion. In contrast, 80% of sheep that first received LPS-infusion developed TRALI following transfusion with "stored PRBC." The decreased mean arterial pressure and cardiac output as well as increased central venous pressure and body temperature were more severe for TRALI induced by "stored PRBC" than by "stored PLT." Storage-related accumulation of several factors was demonstrated in both "stored PRBC" and "stored PLT", and was associated with increased in vitro neutrophil priming. Concentrations of several factors were higher in the "stored PRBC" than in the "stored PLT," however, there was no difference to neutrophil priming in vitro.

Conclusions

In this in vivo ovine model, both recipient and blood product factors contributed to the development of TRALI. Sick (LPS infused) sheep rather than healthy (saline infused) sheep predominantly developed TRALI when transfused with supernatant from stored but not fresh PRBC. "Stored PRBC" induced a more severe injury than "stored PLT" and had a different storage lesion profile, suggesting that these outcomes may be associated with storage lesion factors unique to each blood product type. Therefore, the transfusion of fresh rather than stored PRBC may minimise the risk of TRALI.

Goal-directed therapy in small animal critical illness

Monitoring critically ill patients can be a daunting task even for experienced clinicians. Goal-directed therapy is a technique involving intensive monitoring and aggressive management of hemodynamics in patients with high risk of morbidity and mortality. The aim of goal-directed therapy is to ensure adequate tissue oxygenation and survival. This article reviews commonly used diagnostics in critical care medicine and what the information gathered signifies and discusses clinical decision making on the basis of diagnostic test results. One example is early goal-directed therapy for severe sepsis and septic shock. The components and application of goals in early goal-directed therapy are discussed.