Hemodynamic Instability in Sepsis

Application of Cardiovascular Physiology to the Critically Ill Patient

OBJECTIVES

To use the ventricular pressure-volume relationship and time-varying elastance model to provide a foundation for understanding cardiovascular physiology and pathophysiology, interpreting advanced hemodynamic monitoring, and for illustrating the physiologic basis and hemodynamic effects of therapeutic interventions. We will build on this foundation by using a cardiovascular simulator to illustrate the application of these principles in the care of patients with severe sepsis, cardiogenic shock, and acute mechanical circulatory support.

DATA SOURCES

Publications relevant to the discussion of the time-varying elastance model, cardiogenic shock, and sepsis were retrieved from MEDLINE. Supporting evidence was also retrieved from MEDLINE when indicated.

STUDY SELECTION, DATA EXTRACTION, AND SYNTHESIS

Data from relevant publications were reviewed and applied as indicated.

CONCLUSIONS

The ventricular pressure-volume relationship and time-varying elastance model provide a foundation for understanding cardiovascular physiology and pathophysiology. We have built on this foundation by using a cardiovascular simulator to illustrate the application of these important principles and have demonstrated how complex pathophysiologic abnormalities alter clinical parameters used by the clinician at the bedside.

Neonatal sepsis and cardiovascular dysfunction I: mechanisms and pathophysiology

The highest incidence of sepsis across all age groups occurs in neonates leading to substantial mortality and morbidity. Cardiovascular dysfunction frequently complicates neonatal sepsis including biventricular systolic and/or diastolic dysfunction, vasoregulatory failure, and pulmonary arterial hypertension. The haemodynamic response in neonatal sepsis can be hyperdynamic or hypodynamic and the underlying pathophysiological mechanisms are heterogeneous. The diagnosis and definition of both neonatal sepsis and cardiovascular dysfunction complicating neonatal sepsis are challenging and not consensus-based. Future developments in neonatal sepsis management will be facilitated by common definitions and datasets especially in neonatal cardiovascular optimisation. IMPACT: Cardiovascular dysfunction is common in neonatal sepsis but there is no consensus-based definition, making calculating the incidence and designing clinical trials challenging. Neonatal cardiovascular dysfunction is related to the inflammatory response, which can directly target myocyte function and systemic haemodynamics.

High Respiratory and Cardiac Drive Exacerbate Secondary Lung Injury in Patients With Critical Illness

The high respiratory and cardiac drive is essential to the host-organ unregulated response. When a primary disease and an unregulated secondary response are uncontrolled, the patient may present in a high respiratory and cardiac drive state. High respiratory drive can cause damage to the lungs, pulmonary circulation, and diaphragm, while high cardiac drive can lead to fluid leakage and infiltration as well as pulmonary interstitial edema. A "respiratory and cardiac dual high drive" state may be a sign of an unregulated response and can lead to secondary lung injury through the increase of transvascular pressure and pulmonary microcirculation injury. Ultrasound examination of the lung, heart, and diaphragm is important when evaluating the phenotype of high respiratory drive in critically ill patients. Ultrasound assessment can guide sedation, analgesia, and antistress treatment and reduce the risk of high respiratory and cardiac drive-induced lung injury in these patients.

Preload Responsiveness in Patients With Acute Respiratory Distress Syndrome Managed With Extracorporeal Membrane Oxygenation

A restrictive fluid strategy is recommended in patients with acute respiratory distress syndrome (ARDS) managed with venovenous extracorporeal membrane oxygenation (VV ECMO). However, there are no established predictors for preload responsiveness in these patients. In 20 ARDS patients managed with VV ECMO, transesophageal echocardiography was used to repeatedly evaluate dynamic parameters of the left (velocity and stroke volume variation) and right ventricular outflow tract (velocity [respiratory variations of the maximal Doppler velocity in the truncus pulmonalis {ΔV max TP}] and velocity time integral [respiratory variation of the velocity time integral measured in the truncus pulmonalis {ΔVTI_TP}] variation in the truncus pulmonalis), the diameter variation in the superior and inferior vena cava and stroke volume variation measured by pulse contour analysis (SVV_PCA). Patients were categorized as responders and nonresponders according to an increase in stroke volume measured by echocardiography during a Passive Leg Raise Test with a cutoff value ≥10%. The final analysis includes 86 measurements. Predictive values for preload responsiveness were found for ΔV max TP (area under the curve [AUC] of 0.64), ΔVTI_TP (AUC 0.67), and SVV_PCA (AUC 0.74). In conclusion, SVV_PCA and, to a lesser extent, ΔV max TP and ΔVTI_TP are the most accurate parameters to predict preload responsiveness in ARDS patients managed with VV ECMO. Transesophageal echocardiography offers no advantages over pulse contour analysis for predicting preload responsiveness and provides only intermittent monitoring and assessment.

Echocardiographic parameters in COVID-19 patients and their association with ICU mortality: a prospective multicenter observational study

BACKGROUND

Echocardiography has become an integral part of the management of critically ill patients. It helps to diagnose and treat various conditions. COVID-19 patients can develop cardiac dysfunction. We planned to study the echocardiographic parameters in COVID-19 patients.

METHODS

We conducted a prospective observational multicenter study after institutional ethical committee approval. COVID-19 pneumonia patients admitted to the intensive care unit (ICU) were enrolled. The echocardiographic evaluation was done within 24-48 hours of admission. Assessment of the left and right heart with systolic and left ventricular diastolic function evaluation was done. The primary outcome was ICU mortality. The secondary outcomes were the length of ICU stay and duration of mechanical ventilation.

RESULTS

Among 573 patients mean age was 57.17 (14.67) with 68.60% being males. On day 1 of ICU, invasive mechanical ventilation was used in 257 (45%) patients. One hundred and forty-eight (25.83%) patients were on vasopressors when echocardiography was performed. Severe left ventricle (LV) systolic dysfunction was seen in 8.7% of patients and had higher odds of mortality [2.48(1.058-5.807), p = 0.037] followed by E and e' with odds ratio of [0.984(0.971-0.998), p = 0.021] and 0.897 (0.805-0.998), p = 0.046], respectively. E/e' indicative of filling pressure of the LV was not found to be significant. Troponin I, E/A, and RV dilatation were similar among survivors and non-survivors.

CONCLUSION

Echocardiographic evaluation in COVID-19 patients showed severe LV systolic dysfunction was associated with ICU mortality. E/e' was not found to be significant but lower e' was associated with higher mortality. Trial registration IEC 131/2020, CTRI/2020/06/025858 date 13th June 2020.

Ventriculo-arterial (un)coupling in septic shock: Impact of current and upcoming hemodynamic drugs

Sepsis is an archetype of distributive shock and combines different levels of alterations in preload, afterload, and often cardiac contractility. The use of hemodynamic drugs has evolved over the past few years, along with the invasive and non-invasive tools used to measure these components in real time. However, none of them is impeccable, which is why the mortality of septic shock remains too high. The concept of ventriculo-arterial coupling (VAC) allows for the integration of these three fundamental macroscopic hemodynamic components. In this mini review, we discuss the knowledge, tools, and limitations of VAC measurement, along with the evidence supporting ventriculo-arterial uncoupling in septic shock. Finally, the impact of recommended hemodynamic drugs and molecules on VAC is detailed.

THE ROLES OF EXTRACELLULAR VESICLES IN SEPSIS AND SYSTEMIC INFLAMMATORY RESPONSE SYNDROME

ABSTRACT

Sepsis is a life-threatening organ dysfunction, caused by dysregulation of the host response to infection. To understand the underlying mechanisms of sepsis, the vast spectrum of extracellular vesicles (EVs) is gaining importance in this research field. A connection between EVs and sepsis was shown in 1998 in an endotoxemia pig model. Since then, the number of studies describing EVs as markers and mediators of sepsis increased steadily. Extracellular vesicles in sepsis could be friends and foes at the same time depending on their origin and cargo. On the one hand, transfer of EVs or outer membrane vesicles can induce sepsis or systemic inflammatory response syndrome with comparable efficiency as well-established methods, such as cecal ligation puncture or lipopolysaccharide injection. On the other hand, EVs could provide certain therapeutic effects, mediated via reduction of reactive oxygen species, inflammatory cytokines and chemokines, influence on macrophage polarization and apoptosis, as well as increase of anti-inflammatory cytokines. Moreover, EVs could be helpful in the diagnosis of sepsis. Extracellular vesicles of different cellular origin, such as leucocytes, macrophages, platelets, and granulocytes, have been suggested as potential sepsis biomarkers. They ensure the diagnosis of sepsis earlier than classical clinical inflammation markers, such as C-reactive protein, leucocytes, or IL-6. This review summarizes the three roles of EVs in sepsis-mediator/inducer, biomarker, and therapeutic tool.

Right ventricular outflow tract Doppler flow analysis and pulmonary arterial coupling by transthoracic echocardiography in sepsis: a retrospective exploratory study

INTRODUCTION

Right ventricular (RV) and pulmonary vascular dysfunction appear to be common in sepsis. RV performance is frequently assessed in isolation, yet its close relationship to afterload means combined analysis with right ventricular outflow tract (RVOT) Doppler and RV-pulmonary arterial (RV-PA) coupling may be more informative than standard assessment techniques. Data on feasibility and utility of these parameters in sepsis are lacking and were explored in this study.

METHODS

This is a retrospective study over a 3-year period of one-hundred and thirty-one patients admitted to ICU with sepsis who underwent transthoracic echocardiography (TTE) with RVOT pulsed wave Doppler. RVOT Doppler flow and RV-PA coupling was evaluated alongside standard measurements of RV systolic function and pulmonary pressures. RVOT Doppler analysis included assessment of pulmonary artery acceleration time (PAAT), velocity time integral and presence of notching. RV-PA coupling was assessed using tricuspid annular planar systolic excursion/pulmonary artery systolic pressure (TAPSE/PASP) ratio.

RESULTS

PAAT was measurable in 106 (81%) patients, and TAPSE/PASP was measurable in 77 (73%). Seventy-three (69%) patients had a PAAT of ≤ 100 ms suggesting raised pulmonary vascular resistance (PVR) is common. RVOT flow notching occurred in 15 (14%) of patients. TRV was unable to be assessed in 24 (23%) patients where measurement of PAAT was possible. RV dysfunction (RVD) was present in 28 (26%), 26 (25%) and 36 (34%) patients if subjective assessment, TAPSE < 17 mm and RV dilatation definitions were used, respectively. There was a trend towards shorter PAAT with increasing severity of RVD. RV-PA uncoupling defined as a TAPSE/PASP < 0.31 mm/mmHg was present in 15 (19%) patients. As RV dilatation increased the RV-PA coupling ratio decreased independent of LV systolic function, whereas TAPSE appeared to be more susceptible to changes in LV systolic function.

CONCLUSION

Raised PVR and RV-PA uncoupling is seen in a significant proportion of patients with sepsis. Non-invasive assessment with TTE is feasible. The role of these parameters in assisting improved definitions of RVD, as well as their therapeutic and prognostic utility against standard parameters, deserves further investigation.

Hemodynamic effects and tolerance of dobutamine for myocardial dysfunction during septic shock: An observational multicenter prospective echocardiographic study

Background

The role of dobutamine during septic shock resuscitation is still controversial.

Methods

The aim of this prospective multicentre study was to comprehensively characterize the hemodynamic response of septic shock patients with systolic myocardial dysfunction to incremental doses of dobutamine (0, 5, 10, and 15 μg/kg/min).

Results

Thirty two patients were included in three centers. Dobutamine significantly increased contractility indices of both ventricles [crude and afterload-adjusted left ventricular (LV) ejection fraction, global LV longitudinal peak systolic strain, tissue Doppler peak systolic wave at mitral and tricuspid lateral annulus, and tricuspid annular plane excursion) as well as global function indices (stroke volume and cardiac index) and diastolic function (increased e' and decreased E/e' ratio at lateral mitral annulus). Dobutamine also induced a significant decrease in arterial pressure and cardiac afterload indices (effective arterial elastance, systemic vascular resistance and diastolic shock index). Oxygen transport, oxygen consumption and carbon dioxide production all increased with dobutamine, without change in the respiratory quotient or lactate. Dobutamine was discontinued for poor tolerance in a majority of patients (n = 21, 66%) at any dose and half of patients (n = 15, 47%) at low-dose (5 μg/kg/min). Poor tolerance to low-dose dobutamine was more frequent in case of acidosis, was associated with lower vasopressor-free days and survival at day-14.

Conclusion

In patients with septic myocardial dysfunction, dobutamine induced an overall improvement of echocardiographic parameters of diastolic and systolic function, but was poorly tolerated in nearly two thirds of patients, with worsening vasoplegia. Patients with severe acidosis seemed to have a worse response to dobutamine.

Evaluation of a Meropenem and Piperacillin Monitoring Program in Intensive Care Unit Patients Calls for the Regular Assessment of Empirical Targets and Easy-to-Use Dosing Decision Tools

The drug concentrations targeted in meropenem and piperacillin/tazobactam therapy also depend on the susceptibility of the pathogen. Yet, the pathogen is often unknown, and antibiotic therapy is guided by empirical targets. To reliably achieve the targeted concentrations, dosing needs to be adjusted for renal function. We aimed to evaluate a meropenem and piperacillin/tazobactam monitoring program in intensive care unit (ICU) patients by assessing (i) the adequacy of locally selected empirical targets, (ii) if dosing is adequately adjusted for renal function and individual target, and (iii) if dosing is adjusted in target attainment (TA) failure. In a prospective, observational clinical trial of drug concentrations, relevant patient characteristics and microbiological data (pathogen, minimum inhibitory concentration (MIC)) for patients receiving meropenem or piperacillin/tazobactam treatment were collected. If the MIC value was available, a target range of 1–5 × MIC was selected for minimum drug concentrations of both drugs. If the MIC value was not available, 8–40 mg/L and 16–80 mg/L were selected as empirical target ranges for meropenem and piperacillin, respectively. A total of 356 meropenem and 216 piperacillin samples were collected from 108 and 96 ICU patients, respectively. The vast majority of observed MIC values was lower than the empirical target (meropenem: 90.0%, piperacillin: 93.9%), suggesting empirical target value reductions. TA was found to be low (meropenem: 35.7%, piperacillin 50.5%) with the lowest TA for severely impaired renal function (meropenem: 13.9%, piperacillin: 29.2%), and observed drug concentrations did not significantly differ between patients with different targets, indicating dosing was not adequately adjusted for renal function or target. Dosing adjustments were rare for both drugs (meropenem: 6.13%, piperacillin: 4.78%) and for meropenem irrespective of TA, revealing that concentration monitoring alone was insufficient to guide dosing adjustment. Empirical targets should regularly be assessed and adjusted based on local susceptibility data. To improve TA, scientific knowledge should be translated into easy-to-use dosing strategies guiding antibiotic dosing.

Echocardiography findings in COVID-19 patients admitted to intensive care units: a multi-national observational study (the ECHO-COVID study)

PURPOSE

Severely ill patients affected by coronavirus disease 2019 (COVID-19) develop circulatory failure. We aimed to report patterns of left and right ventricular dysfunction in the first echocardiography following admission to intensive care unit (ICU).

METHODS

Retrospective, descriptive study that collected echocardiographic and clinical information from severely ill COVID-19 patients admitted to 14 ICUs in 8 countries. Patients admitted to ICU who received at least one echocardiography between 1st February 2020 and 30th June 2021 were included. Clinical and echocardiographic data were uploaded using a secured web-based electronic database (REDCap).

RESULTS

Six hundred and seventy-seven patients were included and the first echo was performed 2 [1, 4] days after ICU admission. The median age was 65 [56, 73] years, and 71% were male. Left ventricle (LV) and/or right ventricle (RV) systolic dysfunction were found in 234 (34.5%) patients. 149 (22%) patients had LV systolic dysfunction (with or without RV dysfunction) without LV dilatation and no elevation in filling pressure. 152 (22.5%) had RV systolic dysfunction. In 517 patients with information on both paradoxical septal motion and quantitative RV size, 90 (17.4%) had acute cor pulmonale (ACP). ACP was associated with mechanical ventilation (OR > 4), pulmonary embolism (OR > 5) and increased PaCO₂. Exploratory analyses showed that patients with ACP and older age were more likely to die in hospital (including ICU).

CONCLUSION

Almost one-third of this cohort of critically ill COVID-19 patients exhibited abnormal LV and/or RV systolic function in their first echocardiography assessment. While LV systolic dysfunction appears similar to septic cardiomyopathy, RV systolic dysfunction was related to pressure overload due to positive pressure ventilation, hypercapnia and pulmonary embolism. ACP and age seemed to be associated with mortality in this cohort.

Assessing Fluid Intolerance with Doppler Ultrasonography: A Physiological Framework

Ultrasonography is becoming the favored hemodynamic monitoring utensil of emergentologists, anesthesiologists and intensivists. While the roles of ultrasound grow and evolve, many clinical applications of ultrasound stem from qualitative, image-based protocols, especially for diagnosing and managing circulatory failure. Often, these algorithms imply or suggest treatment. For example, intravenous fluids are opted for or against based upon ultrasonographic signs of preload and estimation of the left ventricular ejection fraction. Though appealing, image-based algorithms skirt some foundational tenets of cardiac physiology; namely, (1) the relationship between cardiac filling and stroke volume varies considerably in the critically ill, (2) the correlation between cardiac filling and total vascular volume is poor and (3) the ejection fraction is not purely an appraisal of cardiac function but rather a measure of coupling between the ventricle and the arterial load. Therefore, management decisions could be enhanced by quantitative approaches, enabled by Doppler ultrasonography. Both fluid ‘responsiveness’ and ‘tolerance’ are evaluated by Doppler ultrasound, but the physiological relationship between these constructs is nebulous. Accordingly, it is argued that the link between them is founded upon the Frank–Starling–Sarnoff relationship and that this framework helps direct future ultrasound protocols, explains seemingly discordant findings and steers new routes of enquiry.

Hyperdynamic left ventricular ejection fraction is associated with higher mortality in COVID-19 patients

Study objective

To compare the characteristics and outcomes of COVID-19 patients with a hyperdynamic LVEF (HDLVEF) to those with a normal or reduced LVEF.

Design

Retrospective study.

Setting

Rush University Medical Center.

Participants

Of the 1682 adult patients hospitalized with COVID-19, 419 had a transthoracic echocardiogram (TTE) during admission and met study inclusion criteria.

Interventions

Participants were divided into reduced (LVEF < 50%), normal (≥50% and <70%), and hyperdynamic (≥70%) LVEF groups.

Main outcome measures

LVEF was assessed as a predictor of 60-day mortality. Logistic regression was used to adjust for age and BMI.

Results

There was no difference in 60-day mortality between patients in the reduced LVEF and normal LVEF groups (adjusted odds ratio [aOR] 0.87, p = 0.68). However, patients with an HDLVEF were more likely to die by 60 days compared to patients in the normal LVEF group (aOR 2.63 [CI: 1.36–5.05]; p < 0.01). The HDLVEF group was also at higher risk for 60-day mortality than the reduced LVEF group (aOR 3.34 [CI: 1.39–8.42]; p < 0.01).

Conclusion

The presence of hyperdynamic LVEF during a COVID-19 hospitalization was associated with an increased risk of 60-day mortality, the requirement for mechanical ventilation, vasopressors, and intensive care unit.

Right Ventricular Function in Acute Respiratory Distress Syndrome: Impact on Outcome, Respiratory Strategy and Use of Veno-Venous Extracorporeal Membrane Oxygenation

Acute respiratory distress syndrome (ARDS) is characterized by protein-rich alveolar edema, reduced lung compliance and severe hypoxemia. Despite some evidence of improvements in mortality over recent decades, ARDS remains a major public health problem with 30% 28-day mortality in recent cohorts. Pulmonary vascular dysfunction is one of the pivot points of the pathophysiology of ARDS, resulting in a certain degree of pulmonary hypertension, higher levels of which are associated with morbidity and mortality. Pulmonary hypertension develops as a result of endothelial dysfunction, pulmonary vascular occlusion, increased vascular tone, extrinsic vessel occlusion, and vascular remodeling. This increase in right ventricular (RV) afterload causes uncoupling between the pulmonary circulation and RV function. Without any contractile reserve, the right ventricle has no adaptive reserve mechanism other than dilatation, which is responsible for left ventricular compression, leading to circulatory failure and worsening of oxygen delivery. This state, also called severe acute cor pulmonale (ACP), is responsible for excess mortality. Strategies designed to protect the pulmonary circulation and the right ventricle in ARDS should be the cornerstones of the care and support of patients with the severest disease, in order to improve prognosis, pending stronger evidence. Acute cor pulmonale is associated with higher driving pressure (≥18 cmH₂O), hypercapnia (PaCO₂ ≥ 48 mmHg), and hypoxemia (PaO₂/FiO₂ < 150 mmHg). RV protection should focus on these three preventable factors identified in the last decade. Prone positioning, the setting of positive end-expiratory pressure, and inhaled nitric oxide (INO) can also unload the right ventricle, restore better coupling between the right ventricle and the pulmonary circulation, and correct circulatory failure. When all these strategies are insufficient, extracorporeal membrane oxygenation (ECMO), which improves decarboxylation and oxygenation and enables ultra-protective ventilation by decreasing driving pressure, should be discussed in seeking better control of RV afterload. This review reports the pathophysiology of pulmonary hypertension in ARDS, describes right heart function, and proposes an RV protective approach, ranging from ventilatory settings and prone positioning to INO and selection of patients potentially eligible for veno-venous extracorporeal membrane oxygenation (VV ECMO).

Afterload-related cardiac performance predicts prognosis in critical ill patients with sepsis: A prospective observational pilot study

ABSTRACT

To investigate the usefulness of afterload-related cardiac performance (ACP) for assessing cardiac impairment and predicting prognosis in septic patients.Adult patients with sepsis in the intensive care unit were included. Cardiac output, cardiac index, cardiac power index, and ACP were calculated at the time of admission (D0) and 48-72 h after admission (D3). They were correlated with Acute Physiology and Chronic Health Evaluation II and sequential organ failure assessment scores, then the prognostic values were analyzed.A total of 41 patients with sepsis were selected. ACP showed a stronger negative correlation with Acute Physiology and Chronic Health Evaluation II and sequential organ failure assessment scores than cardiac output, cardiac index, and cardiac power index. ACP predicted 28-day mortality with an area under the curve of 0.775 and 0.976 on D0 and D3, respectively. In addition, most non-survivors had emergent cardiac impairment (ACP ≤ 80%) on D0, and cardiac function was deteriorated on D3. Survival analysis showed that the patients with a decreased ACP from D0 to D3 had the highest mortality. The decrease of ACP on D3 was an independent risk factor for mortality (hazard ratio, 11.89; P = .0028).ACP can be used to assess the severity of cardiac impairment in sepsis. Continued decline of ACP during the first 3 days strongly suggests a poor prognosis.

Echocardiographic Assessment of Left Ventricular Systolic and Diastolic Functions in Dogs with Severe Sepsis and Septic Shock; Longitudinal Study

Simple Summary

Sepsis is associated with cardiovascular changes. The aim of the study was to determine sepsis-induced myocardial dysfunction in dogs with severe sepsis and septic shock using transthoracic echocardiography. Clinical, laboratory and cardiologic examinations for the septic dogs were performed at admission, 6 and 24 h, and on the day of discharge from the hospital. Left ventricular (LV) systolic dysfunction, LV diastolic dysfunction, and both types of the dysfunction were present in 13%, 70%, and 9% of dogs with sepsis, respectively. Dogs with LV diastolic dysfunction had a worse outcome and short-term mortality. Transthoracic echocardiography can be used for monitoring cardiovascular dysfunction in dogs with sepsis.

Abstract

The purpose of this study was to monitor left ventricular systolic dysfunction (LVSD) and diastolic dysfunction (LVDD) using transthoracic echocardiography (TTE) in dogs with severe sepsis and septic shock (SS/SS). A prospective longitudinal study using 23 dogs with SS/SS (experimental group) and 20 healthy dogs (control group) were carried out. All the clinical, laboratory and cardiologic examinations for the experimental dogs were performed at admission, 6 and 24 h after the start of treatment and on the day of discharge. LVSD was described as LV ejection fraction (LVEF) < 50%. LVDD was determined when the septal mitral annulus early diastolic velocity (LVEm) was <8 cm/s. LVSD and LVDD were present in 3 and 16 dogs with SS/SS, respectively, with both types of dysfunction present in 2 of the dogs. Although all the dogs with LVSD survived, 8 dogs with LVDD did not. The survival period was significantly shorter in dogs with an LVEm < 8 cm/s (1.3 ± 1.4 days). In conclusion, LVDD, rather than LVSD, was a common cardiovascular abnormality in the septic dogs, and this may be a negative prognostic factor. TTE is a useful tool for the identifying and monitoring of myocardial dysfunction in the dogs with SS/SS.

Hemodynamic clinical phenotyping in septic shock

PURPOSE OF REVIEW

Recent studies have failed to show significant benefit from a uniform strategy, suggesting that hemodynamic management must be individually adapted in septic shock depending on different phenotypes. Different approaches that may be used to this end will be discussed.

RECENT FINDINGS

Fluid management is a cornerstone of resuscitation, as the positive fluid balance has been associated with higher mortality and right ventricular failure. Myocardial evaluation is mandatory, as sepsis patients may present with a hyperkinetic state, left ventricular (systolic and diastolic) and/or right ventricular dysfunction, the latter being associated with higher mortality. Statistical approaches with the identification of hemodynamic clusters based on echocardiographic and clinical parameters might be integrated into daily practice to develop precision medicine. Such approaches may also predict the progression of septic shock.

SUMMARY

Different hemodynamic phenotypes can occur at any stage of sepsis and be associated with one another. The clinician must regularly assess dynamic changes in phenotypes in septic shock patients. Statistical approaches based on machine learning need to be validated by prospective studies.

A trend skill that makes pediatric intensivists stand out: Critical care echocardiography

Recently, the use of point-of-care ultrasonography (POCUS) by pediatricians especially in emergency and intensive care departments has become increasingly popular. Critical care echocardiography (CCE) quickly and accurately identifies cardiac function, allowing intensivists to manage critically ill pediatric patients by manipulating vasoactive-inotrope-fluid treatment based on the echocardiographic results. Training courses for POCUS are increasingly available and more intensivists are learning how to use CCE. In this review, we focus on the importance and utility of CCE in pediatric intensive units and how it assists in the management of hemodynamically unstable pediatric patients. We highlight the common measurements carried out by intensive care specialists and emphasize the role of the CCE methods in PICUs.

Cardiac Manifestations of Coronavirus Disease 2019 (COVID-19): a Multicenter Cohort Study

BACKGROUND

This study aimed to investigate the cardiac manifestations of coronavirus disease 2019 (COVID-19).

METHODS

From February to March 2020, we prospectively and retrospectively enrolled consecutive patients diagnosed with COVID-19. Patient's data such as the demographic characteristics, symptoms, vital signs, laboratory and radiologic findings, electrocardiographic, and echocardiographic data, including the global longitudinal strain (GLS) of both ventricles, were obtained.

RESULTS

Forty patients (median age, 58 years; 50% men) were enrolled in the initial analysis. Patients were classified into severe and nonsevere groups based on the current guidelines. The 13 patients in the severe group were significantly older, had a greater prevalence of bilateral pneumonia and leukocytosis, and higher aspartate transaminase levels than patients in the nonsevere group. Patients in the severe group had a slightly lower left ventricular ejection fraction (LVEF) than those in the nonsevere group (median [interquartile range], 61.0% [58.5%, 62.3%] vs. 66.7% [60.6%, 69.8%], P = 0.015). In a subgroup of 34 patients in whom GLS could be analyzed, patients in the severe group had a significantly impaired left ventricular GLS (LVGLS) than those in the nonsevere group (-18.1% [-18.8%, -17.1%] vs. -21.7% [-22.9%, -19.9%], P = 0.001). There were no significant differences in total wall (RVGLStotal, -19.3% [-23.9%, -18.4%] vs. -24.3% [-26.0%, -22.6%], P = 0.060) and free wall (RVGLSfw, -22.7% [-27.2%, -18.6%] vs. -28.8% [-30.4%, -24.1%], P = 0.066) right ventricle GLS (RVGLS).

CONCLUSION

Patients with severe COVID-19 had lower LVEF and LVGLS. RVGLS was not different between patients with severe and nonsevere COVID-19.

Toll-Like Receptor-Mediated Cardiac Injury during Experimental Sepsis

Sepsis is associated with global cardiac dysfunction and with high mortality rate. The development of septic cardiomyopathy is due to complex interactions of damage-associated molecular patters, cytokines, and complement activation products. The aim of this study was to define the effects of sepsis on cardiac structure, gap junction, and tight junction (TJ) proteins. Sepsis was induced by cecal ligation and puncture in male C57BL/6 mice. After a period of 24 h, the expression of cardiac structure, gap junction, and TJ proteins was determined. Murine HL-1 cells were stimulated with LPS, and mRNA expression of cardiac structure and gap junction proteins, intracellular reactive oxygen species, and troponin I release was analyzed. Furthermore, pyrogenic receptor subtype 7 (P2X7) expression and troponin I release of human cardiomyocytes (iPS) were determined after LPS exposure. In vivo, protein expression of connexin43 and α-actinin was decreased after the onset of polymicrobial sepsis, whereas in HL-1 cells, mRNA expression of connexin43, α-actinin, and desmin was increased in the presence of LPS. Expression of TJ proteins was not affected in vivo during sepsis. Although the presence of LPS and nigericin resulted in a significant troponin I release from HL-1 cells. Sepsis affected cardiac structure and gap junction proteins in mice, potentially contributing to compromised cardiac function.

What should I use next if clinical evaluation and echocardiographic haemodynamic assessment is not enough?

PURPOSE OF REVIEW

To provide an integrated clinical approach to the critically ill patients in shock.

RECENT FINDINGS

The complexity behind shock mechanism has improved in the last decades; as consequence, conventional generalized practices have been questioned, in favour of different approaches, titrated to patient's individual response. Bedside clinical examination has been demonstrated to be a reliable instrument to recognize the mismatch between cardiac function and peripheral oxygen demand. Mottling skin and capillary refill time have been recently proposed using a semi-quantitative approach as reliable tool to guide shock therapy; lactate, ΔCO2 and ScVO2 are also useful to track the effect of the therapies overtime. Critical care echocardiography is useful to assess the source of the shock, to choice the correct the therapy and to customize the therapy. Finally, a more sophisticated and invasive calibrated monitoring should be promptly adopted in case of refractory or mixed shock state to titrate the therapy on predefined goals, avoiding the inappropriate use of fluids and vasoactive drugs.

SUMMARY

Bedside haemodynamic assessment in critically ill patients should be considered an integrated approach supporting the decision-making process and should be based on clinical examination and critical care echocardiography.

Echocardiographic assessment of left ventricular systolic function in neonatal calves with naturally occurring sepsis or septic shock due to diarrhea

Sepsis is associated with clinically relevant cardiovascular changes. The objectives of this study were to evaluate the clinical value of echocardiography for monitoring left ventricular (LV) systolic function in septic calves. A prospective longitudinal study was performed using a convenience sample. Twenty septic calves and 10 healthy calves were enrolled in the study. Arterial blood pressure (BP) was measured and M-mode echocardiography performed to characterize LV systolic function; the latter included measurement of ejection fraction, EF; stroke volume, SVI and cardiac output indexed to body weight, CI; E-point of septal separation, EPSS; pre-ejection period, PEP; ejection time, LVET; ratio of PEP to LVET; velocity of circumferential shortening, Vcf, LV end-diastolic volume index (LVEDVI) and LV end-systolic volume index (LVESVI) on admission and 6, 24, 48 and 72 h later in septic calves and once in healthy calves. Admission data were compared using the Mann-Whitney U test and P < .05 was considered significant. Decreased preload and afterload were present in septic calves, as indicated by marked decreases in BP, LVEDVI, LVESVI, SVI, CI, EPSS when compared to healthy calves. Systolic function appeared adequate in septic calves, based on EF and FS compared to control calves. There was no difference in heart rate, LVET, PEP:LVET, or Vcf between septic and health calves. We conclude that circulatory dysfunction, rather than systolic dysfunction predominates in septic calves. Positive associations on admission between CI and LVEDVI, LVESVI, and SVI support this conclusion. Echocardiographic determination of LVEDVI and CI appears useful in directing treatment in septic calves.

A multiplex analysis of sepsis mediators during human septic shock: a preliminary study on myocardial depression and organ failures

BACKGROUND

The mechanisms of organ failure during sepsis are not fully understood. The hypothesis of circulating factors has been suggested to explain septic myocardial dysfunction. We explored the biological coherence of a large panel of sepsis mediators and their clinical relevance in septic myocardial dysfunction and organ failures during human septic shock.

METHODS

Plasma concentrations of 24 mediators were assessed on the first day of septic shock using a multi-analyte cytokine kit. Septic myocardial dysfunction and organ failures were assessed using left ventricle ejection fraction (LVEF) and the Sequential Organ Failure Assessment score, respectively.

RESULTS

Seventy-four patients with septic shock (and without immunosuppression or chronic heart failure) were prospectively included. Twenty-four patients (32%) had septic myocardial dysfunction (as defined by LVEF < 45%) and 30 (41%) died in ICU. Hierarchical clustering identified three main clusters of sepsis mediators, which were clinically meaningful. One cluster involved inflammatory cytokines of innate immunity, most of which were associated with septic myocardial dysfunction, organ failures and death; inflammatory cytokines associated with septic myocardial dysfunction had an additive effect. Another cluster involving adaptive immunity and repair (with IL-17/IFN pathway and VEGF) correlated tightly with a surrogate of early sepsis resolution (lactate clearance) and ICU survival.

CONCLUSIONS

In this preliminary study, we identified a cluster of cytokines involved in innate inflammatory response associated with septic myocardial dysfunction and organ failures, whereas the IL-17/IFN pathway was associated with a faster sepsis resolution and a better survival.

Cardiovascular clusters in septic shock combining clinical and echocardiographic parameters: a post hoc analysis

PURPOSE

Mechanisms of circulatory failure are complex and frequently intricate in septic shock. Better characterization could help to optimize hemodynamic support.

METHODS

Two published prospective databases from 12 different ICUs including echocardiographic monitoring performed by a transesophageal route at the initial phase of septic shock were merged for post hoc analysis. Hierarchical clustering in a principal components approach was used to define cardiovascular phenotypes using clinical and echocardiographic parameters. Missing data were imputed.

FINDINGS

A total of 360 patients (median age 64 [55; 74]) were included in the analysis. Five different clusters were defined: patients well resuscitated (cluster 1, n = 61, 16.9%) without left ventricular (LV) systolic dysfunction, right ventricular (RV) failure or fluid responsiveness, patients with LV systolic dysfunction (cluster 2, n = 64, 17.7%), patients with hyperkinetic profile (cluster 3, n = 84, 23.3%), patients with RV failure (cluster 4, n = 81, 22.5%) and patients with persistent hypovolemia (cluster 5, n = 70, 19.4%). Day 7 mortality was 9.8%, 32.8%, 8.3%, 27.2%, and 23.2%, while ICU mortality was 21.3%, 50.0%, 23.8%, 42.0%, and 38.6% in clusters 1, 2, 3, 4, and 5, respectively (p < 0.001 for both).

CONCLUSION

Our clustering approach on a large population of septic shock patients, based on clinical and echocardiographic parameters, was able to characterize five different cardiovascular phenotypes. How this could help physicians to optimize hemodynamic support should be evaluated in the future.

Non-invasive hemodynamic evaluation by Doppler echocardiography

The approach for treating a hemodynamically unstable patient remains a diagnostic and therapeutic challenge. Stabilization of the patient should be rapid and effective, but there is not much room for error. This narrow window of intervention makes it necessary to use rapid and accurate hemodynamic evaluation methods. Echocardiography is the method of choice for the bedside evaluation of patients in circulatory shock. In fact, it was intensive care physicians who recognized the potential of Doppler echocardiography for the initial approach to patients in circulatory failure. An echocardiogram allows rapid anatomical and functional cardiac evaluation, which may include non-invasive hemodynamic evaluation using a Doppler study. Such an integrated study may provide data of extreme importance for understanding the mechanisms underlying the hemodynamic instability of the patient to allow the rapid institution of appropriate therapeutic measures. In the present article, we describe the most relevant echocardiographic findings using a practical approach for critical patients with hemodynamic instability.

Cardiac involvement in critically ill patients with leptospirosis: A prospective study using myocardial deformation imaging

BACKGROUND

Myocardial inflammation often complicates leptospirosis, a re-emerging global zoonosis. Leptospirosis associated myocardial dysfunction is equivocal and the pattern of cardiac involvement may not differ from that of sepsis associated myocarditis.

METHODS

We prospectively compared cardiac involvement in 113 intensive care unit patients with severe leptospirosis to 31 patients with sepsis syndrome using a comprehensive assessment comprising of clinical presentation, electrocardiography, two-dimensional echocardiography (with global longitudinal strain calculation), and cardiac biomarker evaluation. Binomial logistic regression was performed to identify independent predictors of left ventricular systolic dysfunction in leptospirosis.

RESULTS

Compared to sepsis syndrome, leptospirosis patients were younger, had higher body mass index measurements and were more likely to be smokers. Electrocardiography abnormalities were common and similar in both groups. Myocardial systolic dysfunction was common in both groups (leptospirosis: 55.86% vs sepsis syndrome: 51.61%, p=0.675) with subclinical left ventricular systolic dysfunction (characterized by abnormal global longitudinal strain and normal left ventricular ejection fraction) being most frequent followed by isolated right ventricular systolic dysfunction, isolated left ventricular systolic dysfunction, and bi-ventricular systolic dysfunction (leptospirosis: 31.43%, 18.42%, 13.16%, 10.53%, respectively; sepsis syndrome: 22.22%, 12.00%, 12.00%, 8.00%, respectively (p>0.05 for each comparator)). Leptospirosis patients had a trend towards greater troponin-T elevation (61.0% vs 40.0%, p=0.057). ST-segment elevation and elevated troponin were independent predictors of reduced left ventricular ejection fraction in leptospirosis.

CONCLUSIONS

Cardiac involvement in leptospirosis appears to be similar to that of sepsis syndrome, with myocardial systolic dysfunction being common. As such, clinical vigilance pertaining to cardiac status is paramount in these high-risk patients.

Providing Transthoracic Echocardiography Training for Intensive Care Unit Trainees: An Educational Improvement Initiative

OBJECTIVE

Transthoracic echocardiography (TTE) is important in the management of critically ill patients, yet it has not been incorporated into many residency programs' curricula. Our objective is to determine if trainees undergoing a 60-minute training session on TTE have improved knowledge, ultrasound skills, and increases the utilization of TTE during their rotation in the intensive care unit (ICU). We will also compare the results of participants with prior TTE exposure to TTE-naïve trainees. Our hypothesis is that after the training, participants' will have improved knowledge and ultrasound skills compared to before training. Our secondary hypotheses are that TTE-naïve trainees will have greater improvements in knowledge scores compared to those who have had prior TTE experience and trainees will increase their use of TTE in the ICU.

DESIGN

Single-center, prospective trial.

SETTING

Brigham and Women's Hospital (academic hospital).

PARTICIPANTS

Residents and fellows rotating through the ICU, at any level of postgraduate training.

RESULTS

Forty-two trainees participated in the study. Statistically significant improvement after training was observed for all multiple choice questions (MCQ) and practical assessments (p < 0.001). When assessing the differences in score improvement between TTE-experienced versus TTE-naïve users, mean score improvements were notably higher for TTE-naïve participants (MCQ: 28.2 ± 11.6; echo clinical: 48.6 ± 23.4) compared to TTE-experienced users (MCQ: 18.6 ± 13.5, p = 0.01; echo clinical: 38.3 ± 30.2, p = 0.04).

CONCLUSIONS

A short didactic presentation on TTE use may be useful in teaching ICU trainees basic TTE skills and encouraging the use of bedside TTE in the ICU.

Optimization of Positive End-Expiratory Pressure Targeting the Best Arterial Oxygen Transport in the Acute Respiratory Distress Syndrome: The OPTIPEP Study

The optimal setting for positive end-expiratory pressure (PEEP) in mechanical ventilation remains controversial in the treatment of acute respiratory distress syndrome (ARDS). The aim of this study was to determine the optimum PEEP level in ARDS, which we defined as the level that allowed the best arterial oxygen delivery (DO2). We conducted a physiologic multicenter prospective study on patients who suffering from ARDS according to standard definition and persistent after 6 hours of ventilation. The PEEP was set to 6 cm H2O at the beginning of the test and then was increased by 2 cm H2O after at least 15 minutes of being stabilized until the plateau pressure achieved 30 cm H2O. At each step, the cardiac output was measured by transesophageal echocardiography and gas blood was sampled. We were able to determine the optimal PEEP for 12 patients. The ratio of PaO2/FiO2 at inclusion was 131 ± 40 with a mean FiO2 of 71 ± 3%. The optimal PEEP level was lower than the higher PEEP despite a constant increase in SaO2. The optimal PEEP levels varied between 8 and 18 cm H2O. Our results show that in patients with ARDS the optimal PEEP differs between each patient and require being determined with monitoring.

Detailing the cardiovascular profile in shock patients

Evaluation of the cardiovascular profile of critically ill patients is one of the most important actions performed in critically ill patients. It allows recognition that the patient is in shock and characterization of the type of circulatory failure. This step is crucial to initiate supportive interventions and to cure the cause responsible for the development of shock. Evaluation of tissue perfusion allows identification of the patient insufficiently resuscitated and also to trigger therapeutic interventions. Monitoring tissue perfusion can be achieved by lactate, venoarterial gradients in PCO₂, and central venous or mixed venous oxygen saturation. Ultimately, monitoring the microcirculation may help not only to identify alterations in tissue perfusion but also to identify the type of alterations: diffuse decrease in microvascular perfusion versus heterogeneity in the alterations, as in sepsis, with well perfused areas in close vicinity to poorly perfused areas. Regarding supportive therapy, a step-by-step approach is suggested, with fluid optimization followed by vasoactive support to preserve perfusion pressure and global and regional blood flows. The different variables should be integrated into decision and management pathways, and therapies adapted accordingly.

Time to re-think the use of dobutamine in sepsis

Dobutamine is commonly used worldwide and included in the protocol for early goal-directed therapy (EGDT). Since the use of dobutamine in EGDT was reported, it has been considered to be an important component, especially in the treatment of septic patients with myocardial dysfunction. However, it is questionable whether dobutamine improves the mortality of sepsis and septic shock.

In three recent randomized controlled trials (ProCESS, ProMISe, and ARISE trials), the frequency of dobutamine use was significantly higher in the EGDT group than in the standard care group, but there were no significant differences in the mortality between the groups. These results suggested that dobutamine use may have been overemphasized despite its insignificant effect on the mortality in septic patients. Further, a propensity score analysis revealed that dobutamine use was associated with higher mortality in patients with septic shock.

Although dobutamine leads to an increase in cardiac index, myocardial oxygen demand also increases, thus increasing the risk of myocardial ischemia and tachyarrhythmia. It is well known that the mortality in sepsis complicated with atrial fibrillation (AFib) is worse than that in sepsis without AFib. A propensity score-matched analysis reported that β-blockers were associated with better survival in patients with sepsis complicated with AFib. Further, a randomized controlled trial reported that a short-acting β-blocker improved the survival in patients with septic shock. These studies also indicated the risk of β-stimulation during sepsis.

Notably, improvements in surrogate markers, such as CI, do not always indicate improvements in patient-centered outcomes, such as mortality. Conversely, some evidence indicates the worsening of patient-centered outcomes despite improvements in surrogate markers.

Thus, available evidence suggests that the benefits of dobutamine in patients with sepsis are unclear, but its use might be harmful rather than beneficial, considering the beneficial effects of β-blockers in sepsis that have been reported in recent clinical studies. From this perspective, we will soon have to rethink regarding dobutamine use in patients with sepsis.

Incidence and evolution of sepsis-induced cardiomyopathy in a cohort of patients with sepsis and septic shock

OBJETIVE

The aim of this study was to establish the incidence of septic cardiomyopathy (SM) in patients with sepsis and septic shock, to describe its characteristics and testing its evolution.

DESIGN

Prospective cohort study.

PARTICIPANTS

We included 57 consecutive patients admitted to Intensive Care Unit, who met criteria of sepsis and septic shock.

PRINCIPAL VARIABLES OF INTEREST

Clinical and biochemical variables were analyzed. An echocardiogram was performed in the first 24hours of admission, determining myocardial function parameters, and if the patients had left ventricular ejection fraction (LVEF)<50%) a second echocardiogram was performed.

AMBIT

Intensive medical and surgical Care Service for Adults in University Hospital.

RESULTS

The mean age of the patients was 62,1±16,3 years. 58% were males. 22.8% had left ventricular dysfunction. The mean LVEF in patients with MS was lower than those without SM (34.1±10.6 vs 60.7±6.94%, P<.001), with complete recovery, in survivors, after the acute event (LVEF at discharge 56.1±6.3%, P=.04). Patients with SM had higher levels of procalcitonin (47.1±35.4 vs 18.9±24.5; P=.02) and higher score on the Sequential Organ Failure Assessment (SOFA score) (9.91±3.82 vs 7.47±3.41; P=.037). Mortality was not significantly different between both groups [4 (30.8%) vs 4 (9.1%); P=.07].

CONCLUSIONS

SM is not uncommon and is related to a higher scores on the severity scales. In the survivors, LVEF normalized after the recovery of the acute event.

Improved Survival in a Long-Term Rat Model of Sepsis Is Associated With Reduced Mitochondrial Calcium Uptake Despite Increased Energetic Demand

OBJECTIVES

To investigate the relationship between prognosis, changes in mitochondrial calcium uptake, and bioenergetic status in the heart during sepsis.

DESIGN

In vivo and ex vivo controlled experimental studies.

SETTING

University research laboratory.

SUBJECTS

Male adult Wistar rats.

INTERVENTIONS

Sepsis was induced by intraperitoneal injection of fecal slurry. Sham-operated animals served as controls. Confocal microscopy was used to study functional and bioenergetic parameters in cardiomyocytes isolated after 24-hour sepsis. Electron microscopy was used to characterize structural changes in mitochondria and sarcoplasmic reticulum. The functional response to dobutamine was assessed in vivo by echocardiography.

MEASUREMENTS AND MAIN RESULTS

Peak aortic blood flow velocity measured at 24 hours was a good discriminator for 72-hour survival (area under the receiver operator characteristic, 0.84 ± 0.1; p = 0.03) and was used in ex vivo experiments at 24 hours to identify septic animals with good prognosis. Measurements from animals with good prognostic showed 1) a smaller increase in mitochondrial calcium content and in nicotinamide adenine dinucleotide fluorescence following pacing and 2) increased distance between mitochondria and sarcoplasmic reticulum on electron microscopy, and 3) nicotinamide adenine dinucleotide redox potential and adenosine triphosphate/adenosine diphosphate failed to reach a new steady state following pacing, suggesting impaired matching of energy supply and demand. In vivo, good prognosis animals had a blunted response to dobutamine with respect to stroke volume and kinetic energy.

CONCLUSIONS

In situations of higher energetic demand decreased mitochondrial calcium uptake may constitute an adaptive cellular response that confers a survival advantage in response to sepsis at a cost of decreased oxidative capacity.

Widespread Down-Regulation of Cardiac Mitochondrial and Sarcomeric Genes in Patients With Sepsis

OBJECTIVES

The mechanism(s) for septic cardiomyopathy in humans is not known. To address this, we measured messenger RNA alterations in hearts from patients who died from systemic sepsis, in comparison to changed messenger RNA expression in nonfailing and failing human hearts.

DESIGN

Identification of genes with altered abundance in septic cardiomyopathy, ischemic heart disease, or dilated cardiomyopathy, in comparison to nonfailing hearts.

SETTING

ICUs at Barnes-Jewish Hospital, St. Louis, MO.

PATIENTS

Twenty sepsis patients, 11 ischemic heart disease, nine dilated cardiomyopathy, and 11 nonfailing donors.

INTERVENTIONS

None other than those performed as part of patient care.

MEASUREMENTS AND MAIN RESULTS

Messenger RNA expression levels for 198 mitochondrially localized energy production components, including Krebs cycle and electron transport genes, decreased by 43% ± 5% (mean ± SD). Messenger RNAs for nine genes responsible for sarcomere contraction and excitation-contraction coupling decreased by 43% ± 4% in septic hearts. Surprisingly, the alterations in messenger RNA levels in septic cardiomyopathy were both distinct from and more profound than changes in messenger RNA levels in the hearts of patients with end-stage heart failure.

CONCLUSIONS

The expression profile of messenger RNAs in the heart of septic patients reveals striking decreases in expression levels of messenger RNAs that encode proteins involved in cardiac energy production and cardiac contractility and is distinct from that observed in patients with heart failure. Although speculative, the global nature of the decreases in messenger RNA expression for genes involved in cardiac energy production and contractility suggests that these changes may represent a short-term adaptive response of the heart in response to acute change in cardiovascular homeostasis.

Vasopressors During Sepsis: Selection and Targets

Clinicians have greatly improved care for septic shock. Urgent resuscitation using intravenous fluids and vasopressors as well as rapid administration of broad spectrum antibiotics are probably the most basic and universally accepted interventions. Various trials have compared different types of vasopressors, associations of vasopressors and inotropes, and pressure targets. End goal-directed therapy algorithms are designed to optimize oxygen delivery by use of fluids, vasopressors, inotropes, and blood products. Patients who have a poor response to resuscitation and patients with known severe ventricular dysfunction might merit advanced hemodynamic monitoring. This review examines important vasopressor and septic shock trials.

Complement and sepsis-induced heart dysfunction

It is well known that cardiac dysfunction develops during sepsis in both humans and in rodents (rats, mice). These defects appear to be reversible, since after "recovery" from sepsis, cardiac dysfunction disappears and the heart returns to its function that was present before the onset of sepsis. Our studies, using in vivo and in vitro models, have demonstrated that C5a and its receptors (C5aR1 and C5aR2) play key roles in cardiac dysfunction developing during sepsis. Use of a neutralizing antibody to C5a largely attenuates cardiac dysfunction and other adverse events developing during sepsis. The molecular basis for cardiac dysfunctions is linked to generation of C5a and its interaction with C5a receptors present on surfaces of cardiomyocytes (CMs). It is established that C5a interactions with C5a receptors leads to significant reductions involving faulty contractility and relaxation in CMs. In addition, C5a interactions with C5a receptors on CMs results in reductions in Na⁺/K⁺-ATPase in CMs. This ATPase is essential for intact action potentials in CMs. The enzymatic activity and protein for this ATPase were strikingly reduced in CMs during sepsis by unknown mechanisms. In addition, C5a interactions with C5aRs also caused reductions in CM homeostatic proteins that regulate cytosolic [Ca²⁺]i in CMs: sarco/endoplasmic reticulum Ca²⁺-ATPase2 (SERCA2) and Na⁺/Ca²⁺ exchanger (NCX). In the absence of C5a receptors, defects in SERCA2 and NCX in CMs after sepsis are strikingly attenuated. These observations suggest new strategies to protect the heart from dysfunction developing during sepsis.

Refractory septic shock in children: a European Society of Paediatric and Neonatal Intensive Care definition

Purpose

Although overall paediatric septic shock mortality is decreasing, refractory septic shock (RSS) is still associated with high mortality. A definition for RSS is urgently needed to facilitate earlier identification and treatment. We aim to establish a European society of paediatric and neonatal intensive care (ESPNIC) experts’ definition of paediatric RSS.

Methods

We conducted a two-round Delphi study followed by an observational multicentre retrospective study. One hundred and fourteen paediatric intensivists answered a clinical case-based, two-round Delphi survey, identifying clinical items consistent with RSS. Multivariate analysis of these items in a development single-centre cohort (70 patients, 30 % mortality) facilitated development of RSS definitions based on either a bedside or computed severity score. Both scores were subsequently tested in a validation cohort (six centres, 424 patients, 11.6 % mortality).

Results

From the Delphi process, the draft definition included evidence of myocardial dysfunction and high blood lactate levels despite high vasopressor treatment. When assessed in the development population, each item was independently associated with the need for extracorporeal life support (ECLS) or death. Resultant bedside and computed septic shock scores had high discriminative power against the need for ECLS or death, with areas under the receiver operating characteristics curve of 0.920 (95 % CI 0.89–0.94), and 0.956 (95 % CI 0.93–0.97), respectively. RSS defined by a bedside score equal to or higher than 2 and a computed score equal to or higher than 3.5 was associated with a significant increase in mortality.

Conclusions

This ESPNIC definition of RSS accurately identifies children with the most severe form of septic shock.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-016-4574-2) contains supplementary material, which is available to authorized users.

The Diagnostic and Therapeutic Impact of Point-of-Care Ultrasonography in the Intensive Care Unit

PURPOSE

In light of point-of-care ultrasonography's (POCUS) recent rise in popularity, assessment of its impact on diagnosis and treatment in the intensive care unit (ICU) is of key importance.

METHODS

Ultrasound examinations were collected through an ultrasound reporting software in 6 multidisciplinary ICU units from 3 university hospitals in Canada and the United States. This database included a self-reporting questionnaire to assess the impact of the ultrasound findings on diagnosis and treatment. We retrieved the results of these questionnaires and analyzed them in relation to which organs were assessed during the ultrasound examination.

RESULTS

One thousand two hundred and fifteen ultrasound studies were performed on 968 patients. Intensivists considered the image quality of cardiac ultrasound to be adequate in 94.7% compared to 99.7% for general ultrasound ( P < .001). The median duration of a cardiac examination was 10 (interquartile range [IQR] 10) minutes compared to 5 (IQR 8) minutes for a general examination ( P < .001). Overall, ultrasound findings led to a change in diagnosis in 302 studies (24.9%) and to a change in management in 534 studies (44.0%). A change in diagnosis or management was reported more frequently for cardiac ultrasound than for general ultrasound (108 [37.1%] vs 127 [16.5%], P < .001) and (170 [58.4%] vs 270 [35.1%], P < .001). Assessment of the inferior vena cava for fluid status emerged as the critical care ultrasound application associated with the greatest impact on management.

CONCLUSION

Point-of-care ultrasonography has the potential to optimize care of the critically ill patients when added to the clinical armamentarium of the intensive care physician.

The Use of Ultrasound in Caring for Patients with Sepsis

Echocardiography is a noninvasive and accurate tool used in the intensive care unit to assess cardiac function and monitor hemodynamics in shocked patients. During severe sepsis or septic shock, several mechanisms can lead to hemodynamic failure and have to be quickly and precisely diagnosed to propose adequate, personalized, and timely hemodynamic therapy. Echocardiography truly provides intensivists with this diagnostic possibility, whether or not there is fluid responsiveness, cardiac dysfunction, or persistent vasoplegia. Acquiring skills in critical care echocardiography is mandatory in improving management and monitoring of patients with sepsis at the bedside. How critical care echocardiography in managing patients with septic shock improves prognosis remains to be elucidated.