Cardiovascular determinants of resuscitation from sepsis and septic shock

Blood pressure response index and clinical outcomes in patients with septic shock: a multicenter cohort study

BACKGROUND

Sepsis is a leading cause of mortality in intensive care units and vasoactive drugs are widely used in septic patients. The cardiovascular response of septic shock patients during resuscitation therapies and the relationship of the cardiovascular response and clinical outcome has not been clearly described.

METHODS

We included adult patients admitted to the ICU with sepsis from Peking Union Medical College Hospital (internal), Medical Information Mart for Intensive Care IV (MIMIC-IV) and eICU Collaborative Research Database (eICU-CRD). The Blood Pressure Response Index (BPRI) was defined as the ratio between the mean arterial pressure and the vasoactive-inotropic score. BRRI was compared with existing risk scores on predicting in-hospital death. The relationship between BPRI and in-hospital mortality was calculated. A XGBoost's machine learning model identified the features that influence short-term changes in BPRI.

FINDINGS

There were 2139, 9455, and 4202 patients in the internal, MIMIC-IV and eICU-CRD cohorts, respectively. BPRI had a better AUROC for predicting in-hospital mortality than SOFA (0.78 vs. 0.73, p = 0.01) and APS (0.78 vs. 0.74, p = 0.03) in the internal cohort. The estimated odds ratio for death per unit decrease in BPRI was 1.32 (95% CI 1.20-1.45) when BPRI was below 7.1 vs. 0.99 (95% CI 0.97-1.01) when BPRI was above 7.1 in the internal cohort; similar relationships were found in MIMIC-IV and eICU-CRD. Respiratory support and latest cumulative 12-h fluid balance were intervention-related features influencing BPRI.

INTERPRETATION

BPRI is an easy, rapid, precise indicator of the response of patients with septic shock to vasoactive drugs. It is a comparable and even better predictor of prognosis than SOFA and APS in sepsis and it is simpler and more convenient in use. The application of BPRI could help clinicians identify potentially at-risk patients and provide clues for treatment.

FUNDING

Fundings for the Beijing Municipal Natural Science Foundation; the National High Level Hospital Clinical Research Funding; the CAMS Innovation Fund for Medical Sciences (CIFMS) from Chinese Academy of Medical Sciences and the National Key R&D Program of China, Ministry of Science and Technology of the People's Republic of China.

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.

Development and Clinical Application of Left Ventricular-Arterial Coupling Non-Invasive Assessment Methods

The constant and dynamic interaction between ventricular function and arterial afterload, known as ventricular-arterial coupling, is key to understanding cardiovascular pathophysiology. Ventricular-arterial coupling has traditionally been assessed invasively as the ratio of effective arterial elastance over end-systolic elastance (Ea/Ees), calculated from information derived from pressure-volume loops. Over the past few decades, numerous invasive and non-invasive simplified methods to estimate the elastance ratio have been developed and applied in clinical investigation and practice. The echocardiographic assessment of left ventricular Ea/Ees, as proposed by Chen and colleagues, is the most widely used method, but novel echocardiographic approaches for ventricular-arterial evaluation such as left ventricle outflow acceleration, pulse-wave velocity, and the global longitudinal strain or global work index have arisen since the former was first published. Moreover, multimodal imaging or artificial intelligence also seems to be useful in this matter. This review depicts the progressive development of these methods along with their academic and clinical application. The left ventricular-arterial coupling assessment may help both identify patients at risk and tailor specific pharmacological or interventional treatments.

Effect of age and gender on ventricular-arterial coupling estimated using a non-invasive technique

BACKGROUND

Left ventricular-arterial coupling is assessed as the ratio of left ventricular end-systolic elastance (Ees) to arterial elastance (Ea). Previous studies have introduced non-invasive estimations of Ees/Ea. It requires only four variables, namely pre-ejection period, ejection time, end-systolic pressure and diastolic pressure. The aims of the present study were to clarify the reference values of Ees/Ea estimated using the noninvasive technique, and to investigate the effects of age and gender on Ees/Ea in healthy subjects.

METHODS

This retrospective study utilized data from healthy, 30-79-year-old subjects. We recorded electrocardiogram, phonocardiogram, and brachial arterial pulse waves simultaneously using the vascular screening system, and used the observed variables to calculate Ees/Ea. We separated subjects into five groups according to their age and compared Ees/Ea among the different age groups.

RESULTS

The study included 2114 males and 2292 females. Ees/Ea ranged from 1.87 to 2.04 in males, and 1.98 to 2.32 in females. We observed no age-related differences in Ees/Ea in males (p = 0.10), and significant differences in females (p < 0.001). Ees/Ea in males was not different compared to those in females in 60-69-year-old group (p = 0.92). Whereas Ees/Ea was higher in females compared to those in males in the other age groups. The differences between medians of Ees/Ea in males and those in females were 0.45 (p < 0.001), 0.24 (p < 0.001), 0.13 (p = 0.01), and 0.13 (p = 0.03) in 30-39, 40-49, 50-59, and 70-79-year-old age groups, respectively.

CONCLUSIONS

We clarified the reference values of Ees/Ea in healthy subjects. The effect of age on Ees/Ea is different in males and females, although Ees/Ea is maintained within a relatively narrow range in all subjects.

Mean systemic filling pressure and venous return to assess the effects of passive leg raising and volume expansion in acute circulatory failure patients: a posthoc analysis of a multi-centre prospective study

BACKGROUND

The main aim of the study was to investigate the behaviours of the mean systemic filling pressure (Pmsf), calculated by the mathematical method, and its derived variables of venous return after volume expansion (VE) and passive leg raising (PLR), with analysis according to fluid and PLR responsiveness.

METHODS

This was a post-hoc analysis of a multicentre prospective study. We included 202 mechanically ventilated patients with acute circulatory failure. Pmsf, dVR (difference between Pmsf and central venous pressure [CVP]), and resistance to venous return (RVR) were calculated before/after PLR and before/after VE. Fluid- and PLR-responsiveness were defined according to the increase in cardiac index (CI) >15% after VE and >10% after PLR, respectively.

RESULTS

Pmsf increased significantly after VE and PLR in both fluid and PLR-responder and non-responder groups. In fluid-responder patients, the increase in dVR was significantly higher than in non-responder group (1.5 [IQR:1.0-2.0] vs. 0.3 [IQR:-0.1-0.6] mmHg, p < 0.001) because of the larger increase in CVP relative to Pmsf in the non-responder group. The same findings were observed after PLR. RVR significantly decreased only in the fluid-responder and PLR-responder groups after VE and PLR.

CONCLUSIONS

Venous return, derived from the mathematical model, increased in preload-dependent patients after VE and PLR because of the larger increases in Pmsf relative to CVP and the decreases in RVR. In preload-independent patients, VR did not change because of the larger rise in CVP compared to Pmsf after VE and PLR. These findings agree with the physiological model of circulation described by Guyton.

Subclinical cardiac dysfunction may impact on fluid and vasopressor administration during early resuscitation of septic shock

BACKGROUND

According to the Surviving Sepsis Campaign (SSC) fluids and vasopressors are the mainstays of early resuscitation of septic shock while inotropes are indicated in case of tissue hypoperfusion refractory to fluids and vasopressors, suggesting severe cardiac dysfunction. However, septic cardiac disfunction encompasses a large spectrum of severities and may remain "subclinical" during early resuscitation. We hypothesized that "subclinical" cardiac dysfunction may nevertheless influence fluid and vasopressor administration during early resuscitation. We retrospectively reviewed prospectically collected data on fluids and vasoconstrictors administered outside the ICU in patients with septic shock resuscitated according to the SSC guidelines that had reached hemodynamic stability without the use of inotropes. All the patients were submitted to transpulmonary thermodilution (TPTD) hemodynamic monitoring at ICU entry. Subclinical cardiac dysfunction was defined as a TPTD-derived cardiac function index (CFI) ≤ 4.5 min-1.

RESULTS

At ICU admission, subclinical cardiac dysfunction was present in 17/40 patients (42%; CFI 3.6 ± 0.7 min-1 vs 6.6 ± 1.9 min-1; p < 0.01). Compared with patients with normal CFI, these patients had been resuscitate with more fluids (crystalloids 57 ± 10 vs 47 ± 9 ml/kg PBW; p < 0.01) and vasopressors (norepinephrine 0.65 ± 0.25 vs 0.43 ± 0.29 mcg/kg/min; p < 0.05). At ICU admission these patients had lower cardiac index (2.2 ± 0.6 vs 3.6 ± 0.9 L/min/m2, p < 0.01) and higher systemic vascular resistances (2721 ± 860 vs 1532 ± 480 dyn*s*cm-5/m2, p < 0.01).

CONCLUSIONS

In patients with septic shock resuscitated according to the SSC, we found that subclinical cardiac dysfunction may influence the approach to fluids and vasopressor administration during early resuscitation. Our data support the implementation of early, bedside assessment of cardiac function during early resuscitation of septic shock.

Comparison of Norepinephrine and Terlipressin vs Norepinephrine Alone for Management of Septic Shock: Few Concerns

How to cite this article: Khera D, Suresh C. Comparison of Norepinephrine and Terlipressin vs Norepinephrine Alone for Management of Septic Shock: Few Concerns. Indian J Crit Care Med 2023;27(8):605.

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 Chronological Demographics of Ventricular-Arterial Decoupling in Patients with Sepsis and Septic Shock: A Prospective Observational Study

BACKGROUND

Ventricular-arterial coupling (V-A coupling) recently gathers attention from clinicians to evaluate the interaction between afterload and left ventricular systolic function. We aimed to describe the chronological demographics of V-A decoupling in patients with sepsis and septic shock through the clinical course.

METHOD

We conducted a single-center prospective observational study comprising adult patients with sepsis and septic shock admitted to the tertiary care hospital between 04/2017 and 03/2019. Patients' characteristics, lab data on admission, and echocardiographic parameters including Ea and Ees on the day- 1, 2, 3, 7, and 14-28 were collected. V-A decoupling was defined as Ea/Ees ≥ 1.36.

RESULTS

Seventy-one patients with sepsis or septic shock were enrolled. The prevalence of V-A decoupling was as follows; day-1: 25.4%, day-2: 23.8%, day-3: 13.3%, day-7: 18.5%, day-14-28: 30.3%, respectively. Ea was higher in patients with V-A decoupling than those without throughout the clinical course (day1; 2.8 vs. 1.8, p < 0.01, day2; 2.7 vs. 1.9, p < 0.01, day3; 2.8 vs. 2.1, p = 0.06, day7; 2.7 vs. 1.9, p = 0.02, day14-28; 2.4 vs. 1.8, p = 0.08). This increase in Ea was mainly induced by reduced stroke volume (SV) as well as high systolic blood pressure (SBP) in the earlier course of sepsis but only by increased SBP in the later course of sepsis. Ees was lower in patients with V-A decoupling than those without throughout the clinical course (day1; 1.3 vs. 2.1, p < 0.01, day2; 1.5 vs. 2.3, p < 0.01, day3; 1.6 vs. 2.3, p = 0.02, day7; 1.8 vs. 2.3, p = 0.01, day14-28; 1.2 vs. 1.9, p = 0.07).

CONCLUSION

We reported that V-A decoupling was commonly seen in patients with sepsis and septic shock. In patients with V-A decoupling, both Ea and Ees were significantly altered, but the causes of these alterations appeared to be changing over the clinical course of sepsis.

Combined Multiomics and In Silico Approach Uncovers PRKAR1A as a Putative Therapeutic Target in Multi-Organ Dysfunction Syndrome

Despite all epidemiological, clinical, and experimental research efforts, therapeutic concepts in sepsis and sepsis-induced multi-organ dysfunction syndrome (MODS) remain limited and unsatisfactory. Currently, gene expression data sets are widely utilized to discover new biomarkers and therapeutic targets in diseases. In the present study, we analyzed MODS expression profiles (comprising 13 sepsis and 8 control samples) retrieved from NCBI-GEO and found 359 differentially expressed genes (DEGs), among which 170 were downregulated and 189 were upregulated. Next, we employed the weighted gene co-expression network analysis (WGCNA) to establish a MODS-associated gene co-expression network (weighted) and identified representative module genes having an elevated correlation with age. Based on the results, a turquoise module was picked as our hub module. Further, we constructed the PPI network comprising 35 hub module DEGs. The DEGs involved in the highest-confidence PPI network were utilized for collecting pathway and gene ontology (GO) terms using various libraries. Nucleotide di- and triphosphate biosynthesis and interconversion was the most significant pathway. Also, 3 DEGs within our PPI network were involved in the top 5 significantly enriched ontology terms, with hypercortisolism being the most significant term. PRKAR1A was the overlapping gene between top 5 significant pathways and GO terms, respectively. PRKAR1A was considered as a therapeutic target in MODS, and 2992 ligands were screened for binding with PRKAR1A. Among these ligands, 3 molecules based on CDOCKER score (molecular dynamics simulated-based score, which allows us to rank the binding poses according to their quality and to identify the best pose for each system) and crucial interaction with human PRKAR1A coding protein and protein kinase-cyclic nucleotide binding domains (PKA RI alpha CNB-B domain) via active site binding residues, viz. Val283, Val302, Gln304, Val315, Ile327, Ala336, Ala337, Val339, Tyr373, and Asn374, were considered as lead molecules.

Ultrasound in Sepsis and Septic Shock-From Diagnosis to Treatment

Sepsis and septic shock are among the leading causes of in-hospital mortality worldwide, causing a considerable burden for healthcare. The early identification of sepsis as well as the individuation of the septic focus is pivotal, followed by the prompt initiation of antibiotic therapy, appropriate source control as well as adequate hemodynamic resuscitation. For years now, both emergency department (ED) doctors and intensivists have used ultrasound as an adjunctive tool for the correct diagnosis and treatment of these patients. Our aim was to better understand the state-of-the art role of ultrasound in the diagnosis and treatment of sepsis and septic shock.

METHODS

We conducted an extensive literature search about the topic and reported on the data from the most significant papers over the last 20 years.

RESULTS

We divided each article by topic and exposed the results accordingly, identifying four main aspects: sepsis diagnosis, source control and procedure, fluid resuscitation and hemodynamic optimization, and echocardiography in septic cardiomyopathy.

CONCLUSION

The use of ultrasound throughout the process of the diagnosis and treatment of sepsis and septic shock provides the clinician with an adjunctive tool to better characterize patients and ensure early, aggressive, as well as individualized therapy, when needed. More data are needed to conclude that the use of ultrasound might improve survival in this subset of patients.

Development of a Nomogram for Predicting Mortality Risk in Sepsis Patients During Hospitalization: A Retrospective Study

Purpose

We attempted to establish a model for predicting the mortality risk of sepsis patients during hospitalization.

Patients and Methods

Data on patients with sepsis were collected from a clinical record mining database, who were hospitalized at the Affiliated Dongyang Hospital of Wenzhou Medical University between January 2013 and August 2022. These included patients were divided into modeling and validation groups. In the modeling group, the independent risk factors of death during hospitalization were determined using univariate and multi-variate regression analyses. After stepwise regression analysis (both directions), a nomogram was drawn. The discrimination ability of the model was evaluated using the area under the curve (AUC) of the receiver operating characteristic (ROC) curve, and the GiViTI calibration chart assessed the model calibration. The Decline Curve Analysis (DCA) was performed to evaluate the clinical effectiveness of the prediction model. Among the validation group, the logistic regression model was compared to the models established by the SOFA scoring system, random forest method, and stacking method.

Results

A total of 1740 subjects were included in this study, 1218 in the modeling population and 522 in the validation population. The results revealed that serum cholinesterase, total bilirubin, respiratory failure, lactic acid, creatinine, and pro-brain natriuretic peptide were the independent risk factors of death. The AUC values in the modeling group and validation group were 0.847 and 0.826. The P values of calibration charts in the two population sets were 0.838 and 0.771. The DCA curves were above the two extreme curves. Moreover, the AUC values of the models established by the SOFA scoring system, random forest method, and stacking method in the validation group were 0.777, 0.827, and 0.832, respectively.

Conclusion

The nomogram model established by combining multiple risk factors could effectively predict the mortality risk of sepsis patients during hospitalization.

Dynamic Arterial Elastance to Predict Mean Arterial Pressure Decrease after Reduction of Vasopressor in Septic Shock Patients

After fluid status optimization, norepinephrine infusion represents the cornerstone of septic shock treatment. De-escalation of vasopressors should be considered with caution, as hypotension increases the risk of mortality. In this prospective observational study including 42 patients, we assess the role of dynamic elastance (EaDyn), i.e., the ratio between pulse pressure variation and stroke volume variation, which can be measured noninvasively by the MostCare monitoring system, to predict a mean arterial pressure (MAP) drop > 10% 30 min after norepinephrine reduction. Patients were divided into responders (MAP falling > 10%) and non-responders (MAP falling < 10%). The receiver-operating-characteristic curve identified an area under the curve of the EaDyn value to predict a MAP decrease > 10% of 0.84. An EaDyn cut-off of 0.84 predicted a MAP drop > 10% with a sensitivity of 0.71 and a specificity of 0.89. In a multivariate logistic regression, EaDyn was significantly and independently associated with MAP decrease (OR 0.001, 95% confidence interval 0.00001−0.081, p < 0.001). The nomogram model for the probability of MAP decrease > 10% showed a C-index of 0.90. In conclusion, in a septic shock cohort, EaDyn correlates well with the risk of decrease of MAP > 10% after norepinephrine reduction.

Autonomic and circulatory alterations persist despite adequate resuscitation in a 5-day sepsis swine experiment

Autonomic and vascular failures are common phenotypes of sepsis, typically characterized by tachycardia despite corrected hypotension/hypovolemia, vasopressor resistance, increased arterial stiffness and decreased peripheral vascular resistance. In a 5-day swine experiment of polymicrobial sepsis we aimed at characterizing arterial properties and autonomic mechanisms responsible for cardiovascular homeostasis regulation, with the final goal to verify whether the resuscitation therapy in agreement with standard guidelines was successful in restoring a physiological condition of hemodynamic profile, cardiovascular interactions and autonomic control. Twenty pigs were randomized to polymicrobial sepsis and protocol-based resuscitation or to prolonged mechanical ventilation and sedation without sepsis. The animals were studied at baseline, after sepsis development, and every 24 h during the 3-days resuscitation period. Beat-to-beat carotid blood pressure (BP), carotid blood flow, and central venous pressure were continuously recorded. The two-element Windkessel model was adopted to study carotid arterial compliance, systemic vascular resistance and characteristic time constant τ. Effective arterial elastance was calculated as a simple estimate of total arterial load. Cardiac baroreflex sensitivity (BRS) and low frequency (LF) spectral power of diastolic BP were computed to assess autonomic activity. Sepsis induced significant vascular and autonomic alterations, manifested as increased arterial stiffness, decreased vascular resistance and τ constant, reduced BRS and LF power, higher arterial afterload and elevated heart rate in septic pigs compared to sham animals. This compromised condition was persistent until the end of the experiment, despite achievement of recommended resuscitation goals by administered vasopressors and fluids. Vascular and autonomic alterations persist 3 days after goal-directed resuscitation in a clinically relevant sepsis model. We hypothesize that the addition of these variables to standard clinical markers may better profile patients' response to treatment and this could drive a more tailored therapy which could have a potential impact on long-term outcomes.

Pathophysiology of fluid administration in critically ill patients

Fluid administration is a cornerstone of treatment of critically ill patients. The aim of this review is to reappraise the pathophysiology of fluid therapy, considering the mechanisms related to the interplay of flow and pressure variables, the systemic response to the shock syndrome, the effects of different types of fluids administered and the concept of preload dependency responsiveness. In this context, the relationship between preload, stroke volume (SV) and fluid administration is that the volume infused has to be large enough to increase the driving pressure for venous return, and that the resulting increase in end-diastolic volume produces an increase in SV only if both ventricles are operating on the steep part of the curve. As a consequence, fluids should be given as drugs and, accordingly, the dose and the rate of administration impact on the final outcome. Titrating fluid therapy in terms of overall volume infused but also considering the type of fluid used is a key component of fluid resuscitation. A single, reliable, and feasible physiological or biochemical parameter to define the balance between the changes in SV and oxygen delivery (i.e., coupling “macro” and “micro” circulation) is still not available, making the diagnosis of acute circulatory dysfunction primarily clinical.

Fluids are drugs used in patients with shock to increase the cardiac output with the aim to improve oxygen delivery to the cells. The response to fluid administration is determined by the physiological interaction of cardiac function and venous return. In septic shock, the beneficial clinical response of fluid administration is rapidly reduced after few hours and fluid titration is crucial to avoid detrimental fluid overload. The fluid challenge is a fluid bolus given at a defined quantity and rate to assess fluid responsiveness.

The ideal fluid for critically ill patients does not exist; however, crystalloids should be used as first choice. Balanced crystalloid solutions may be associated with better outcomes but the evidence is still low. Albumin infusion may have a role in already fluid resuscitated patients at risk of fluid overload.

Fluid administration is integrated into the complex management of pressure and flow “macro” hemodynamic variables, coupled to the “micro” local tissue flow distribution and regional metabolism. Macro-variables are managed by measuring systemic blood pressure and evaluating the global cardiac function. The critical threshold of oxygen delivery to the cells is difficult to estimate, however, several indexes and clinical signs may be considered as surrogate of that, and integrated in a decision-making process at the bedside.

Septic Shock: Phenotypes and Outcomes

INTRODUCTION

Sepsis is a heterogeneous syndrome that results in life-threatening organ dysfunction. Our goal was to determine the relevant variables and patient phenotypes to use in predicting sepsis outcomes.

METHODS

We performed an ancillary study concerning 119 patients with septic shock at intensive care unit (ICU) admittance (T0). We defined clinical worsening as having an increased sequential organ failure assessment (SOFA) score of ≥ 1, 48 h after admission (ΔSOFA ≥ 1). We performed univariate and multivariate analyses based on the 28-day mortality rate and ΔSOFA ≥ 1 and determined three patient phenotypes: safe, intermediate and unsafe. The persistence of the intermediate and unsafe phenotypes after T0 was defined as a poor outcome.

RESULTS

At T0, the multivariate analysis showed two variables associated with 28-day mortality rate: norepinephrine dose and serum lactate concentration. Regarding ΔSOFA ≥ 1, we identified three variables at T0: norepinephrine dose, lactate concentration and venous-to-arterial carbon dioxide difference (P(v-a)CO₂). At T0, the three phenotypes (safe, intermediate and unsafe) were found in 28 (24%), 70 (59%) and 21 (18%) patients, respectively. We thus suggested using an algorithm featuring norepinephrine dose, lactate concentration and P(v-a)CO₂ to predict patient outcomes and obtained an area under the curve (AUC) of 74% (63-85%).

CONCLUSION

Our findings highlight the fact that identifying relevant variables and phenotypes may help physicians predict patient outcomes.

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.

Comparative Effectiveness of Combined IgM-Enriched Immunoglobulin and Extracorporeal Blood Purification Plus Standard Care Versus Standard Care for Sepsis and Septic Shock after Cardiac Surgery

Background

The combination of surgery, bacterial spread-out, and artificial cardiopulmonary bypass surfaces results in a release of key inflammatory mediators leading to an overshooting systemic hyper-inflammatory condition frequently associated with compromised hemodynamics and organ dysfunction. A promising approach could be extracorporeal blood purification therapies in combination with IgM enriched immunoglobulin. This approach might perform a balanced control of both hyper and hypo-inflammatory phases as an immune-modulating intervention.

Methods

We performed a retrospective observational study of patients with proven infection after cardiac surgery between January 2020 and December 2021. Patients were divided into two groups: (1) the first group (Control Group) followed a standard care approach as recommended by the Surviving Sepsis Campaign Guidelines; The second group (Active Group) underwent extracorporeal blood purification therapy (EBPT) in combination with intravenous administration of IgM enriched immunoglobulin 5 mL/kg die for at least three consecutive days, in conjunction with the standard approach (SSC Guidelines). In addition, ventriculo-arterial (V/A) coupling, Interleukin 6 (IL-6), Endotoxin Activity Assay (EAA), Procalcitonin, White Blood Cells (WBC) counts, Sequential Organ Failure Assessment (SOFA) Score and Inotropic Score were assessed in both two groups at different time points.

Results

Fifty-four patients were recruited; 25 were in the Control Group, while 29 participants were in the Active Group. SOFA score significantly improved from baseline [12 (9-16)] until at T 3 [8 (3-13)] in the active group; it was associated with a median EAA reduction from 1.03 (0.39-1.20) at T 0 to 0.41 (0.2-0.9) at T 3 in the active group compared with control group 0.70 (0.50-1.00) at T 0 to 0.70 (0.50-1.00) at T 3 (p < 0.001). V/A coupling tended to be lower in patients of the active arm ranging from 1.9 (1.2-2.7) at T 0 to 0.8 (0.8-2.2) at T 3 than in those of the control arm ranging from 2.1 (1.4-2.2) at T0 to 1.75 (1.45-2.1) at T 3 (p = 0.099). The hemodynamic improvement over time was associated with evident but no significant decrease in inotropic score in the active group compared with the control group. Changes in EAA value from T 0 to T 4 were directly and significantly related (r = 0.39, p = 0.006) to those of V/A coupling.

Conclusions

EBPT, in combination with IgM enriched immunoglobulin, was associated with a mitigated postoperative response of key cytokines with a significant decrease in IL-6, Procalcitonin, and EAA and was associated with improvement of clinical and metabolic parameters.

Venous return and mean systemic filling pressure: physiology and clinical applications

Venous return is the flow of blood from the systemic venous network towards the right heart. At steady state, venous return equals cardiac output, as the venous and arterial systems operate in series. However, unlike the arterial one, the venous network is a capacitive system with a high compliance. It includes a part of unstressed blood, which is a reservoir that can be recruited via sympathetic endogenous or exogenous stimulation. Guyton’s model describes the three determinants of venous return: the mean systemic filling pressure, the right atrial pressure and the resistance to venous return. Recently, new methods have been developed to explore such determinants at the bedside. In this narrative review, after a reminder about Guyton’s model and current methods used to investigate it, we emphasize how Guyton’s physiology helps understand the effects on cardiac output of common treatments used in critically ill patients.

Assessment of Dynamic Changes in Stressed Volume and Venous Return during Hyperdynamic Septic Shock

The present work investigated the dynamic changes in stressed volume (Vs) and other determinants of venous return using a porcine model of hyperdynamic septic shock. Septicemia was induced in 10 anesthetized swine, and fluid challenges were started after the diagnosis of sepsis-induced arterial hypotension and/or tissue hypoperfusion. Norepinephrine infusion targeting a mean arterial pressure (MAP) of 65 mmHg was started after three consecutive fluid challenges. After septic shock was confirmed, norepinephrine infusion was discontinued, and the animals were left untreated until cardiac arrest occurred. Baseline Vs decreased by 7% for each mmHg decrease in MAP during progression of septic shock. Mean circulatory filling pressure (Pmcf) analogue (Pmca), right atrial pressure, resistance to venous return, and efficiency of the heart decreased with time (p < 0.001 for all). Fluid challenges did not improve hemodynamics, but noradrenaline increased Vs from 107 mL to 257 mL (140%) and MAP from 45 mmHg to 66 mmHg (47%). Baseline Pmca and post-cardiac arrest Pmcf did not differ significantly (14.3 ± 1.23 mmHg vs. 14.75 ± 1.5 mmHg, p = 0.24), but the difference between pre-arrest Pmca and post-cardiac arrest Pmcf was statistically significant (9.5 ± 0.57 mmHg vs. 14.75 ± 1.5 mmHg, p < 0.001). In conclusion, the baseline Vs decreased by 7% for each mmHg decrease in MAP during progression of hyperdynamic septic shock. Significant changes were also observed in other determinants of venous return. A new physiological intravascular volume existing at zero transmural distending pressure was identified, termed as the rest volume (Vr).

Experimental validation of a mean systemic pressure analog against zero-flow measurements in porcine VA-ECMO

The mean systemic pressure analog (Pmsa), calculated from running hemodynamic data, estimates mean systemic filling pressure (MSFP). This post hoc study used data from a porcine veno-arterial extracorporeal membrane oxygenation (ECMO) model [n = 9; Sus scrofa domesticus; ES breed (Schweizer Edelschwein)] with eight experimental conditions; Euvolemia [a volume state where ECMO flow produced normal mixed venous saturation (SVO2) without vascular collapse]; three levels of increasing norepinephrine infusion (Vasoconstriction 1-3); status after stopping norepinephrine (Post Vasoconstriction); and three steps of volume expansion (10 mL/kg crystalloid bolus) (Volume Expansion 1-3). In each condition, Pmsa and a "reduced-pump-speed-Pmsa" (Pmsared) were calculated from baseline and briefly reduced pump speeds, respectively. We calculated agreement for absolute values (per condition) and changes (between consecutive conditions) of Pmsa and Pmsared, against MSFP at zero ECMO flow. Euvolemia venous return driving pressure was 5.1 ± 2.0 mmHg. Bland-Altman analysis for Pmsa vs. MSFP (all conditions; 72 data pairs) showed bias (confidence interval) 0.5 (0.1-0.9) mmHg; limits of agreement (LoA) -2.7 to 3.8 mmHg. Bias for ΔPmsa vs. ΔMSFP (63 data pairs): 0.2 (-0.2 to 0.6) mmHg, LoA -3.2 to 3.6 mmHg. Bias for Pmsared vs. MSFP (72 data pairs): 0.0 (-0.3 to -0.3) mmHg; LoA -2.3 to 2.4 mmHg. Bias for ΔPmsared vs. ΔMSFP (63 data pairs) was 0.2 (-0.1 to 0.4) mmHg; LoA -1.8 to 2.1 mmHg. In conclusion, during veno-arterial ECMO, under clinically relevant levels of vasoconstriction and volume expansion, Pmsa accurately estimated absolute and changing values of MSFP, with low between-method precision. The within-method precision of Pmsa was excellent, with a least significant change of 0.15 mmHg.NEW & NOTEWORTHY This is the first study ever to validate the mean systemic pressure analog (Pmsa) against the reference mean systemic filling pressure (MSFP) determined at full arterio-venous pressure equilibrium. Using a porcine ECMO model with clinically relevant levels of vasoconstriction and volume expansion, we showed that Pmsa accurately estimated absolute and changing values of MSFP, with a poor between-method precision. The within-method precision of Pmsa was excellent.

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.

Inferring the Frank-Starling Curve From Simultaneous Venous and Arterial Doppler: Measurements From a Wireless, Wearable Ultrasound Patch

The Frank–Starling relationship is a fundamental concept in cardiovascular physiology, relating change in cardiac filling to its output. Historically, this relationship has been measured by physiologists and clinicians using invasive monitoring tools, relating right atrial pressure (P_ra) to stroke volume (SV) because the P_ra-SV slope has therapeutic implications. For example, a critically ill patient with a flattened P_ra-SV slope may have low P_ra yet fail to increase SV following additional cardiac filling (e.g., intravenous fluids). Provocative maneuvers such as the passive leg raise (PLR) have been proposed to identify these “fluid non-responders”; however, simultaneously measuring cardiac filling and output via non-invasive methods like ultrasound is cumbersome during a PLR. In this Hypothesis and Theory submission, we suggest that a wearable Doppler ultrasound can infer the P_ra-SV relationship by simultaneously capturing jugular venous and carotid arterial Doppler in real time. We propose that this method would confirm that low cardiac filling may associate with poor response to additional volume. Additionally, simultaneous assessment of venous filling and arterial output could help interpret and compare provocative maneuvers like the PLR because change in cardiac filling can be confirmed. If our hypothesis is confirmed with future investigation, wearable monitors capable of monitoring both variables of the Frank–Starling relation could be helpful in the ICU and other less acute patient settings.

Low Dosing Norepinephrine Effects on Cerebral Oxygenation and Perfusion During Pediatric Shock

BACKGROUND

Cerebral hypoperfusion and impaired oxygen delivery during pediatric critical illness may result in acute neurologic injury with subsequent long-term effects on neurodevelopmental outcome. Yet, the impact of norepinephrine on cerebral hemodynamics is unknown in children with shock. We aimed to describe the norepinephrine effects on cerebral perfusion and oxygenation during pediatric shock.

PATIENTS AND METHODS

We conducted an observational multicentre prospective study in 3 French pediatric intensive care units. Children <18 years of age excluding traumatic brain injury were included in the study if they need norepinephrine for shock. Systemic and cerebral hemodynamics were compared between the time of initiation of norepinephrine (T₀), and the steady-state (T_ss). Cardiac output (CO) was measured using ultrasound. Cerebral perfusion was assessed on middle cerebral arteries (MCA) using transcranial doppler ultrasound. Cerebral tissue oxygen saturation (rScO₂) was recorded using near infrared spectroscopy, and we calculated cerebral fractional tissue oxygen extraction (cFTOE = SpO₂-rScO₂/SpO₂).

MAIN RESULTS

Fourteen children (median [IQR] age of 3.5[1; 13.5] years) were included. Norepinephrine at 0.2[0.1; 0.32] μg/kg/min significantly increased mean arterial blood pressure (61[56; 73] mmHg at T_ss vs. 49[42;54] mmHg at T₀, p=10^-3) without change of CO. MCA velocities, pulsatility index, rScO₂, and cFTOE did not significantly change between T₀ and T_ss. Some individuals observed variations in estimated CBF, which slightly improved in 7 patients, remained unchanged in 5, and was impaired in 2. No patient experienced significant variations of rScO₂.

CONCLUSIONS

Low-dosing norepinephrine, despite a homogeneous and significant increase in arterial blood pressure, had little effects on cerebral perfusion and oxygenation during pediatric shock. This reinforces the need for personalized tailored therapies in this population.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT03731104. Registered 6 November, 2018. https://clinicaltrials.gov/ct2/show/NCT03731104.

Hemodynamic effects of different fluid volumes for a fluid challenge in septic shock patients

Background:

It is still unclear what the minimal infusion volume is to effectively predict fluid responsiveness. This study was designed to explore the minimal infusion volume to effectively predict fluid responsiveness in septic shock patients. Hemodynamic effects of fluid administration on arterial load were observed and added values of effective arterial elastance (Ea) in fluid resuscitation were assessed.

Methods:

Intensive care unit septic shock patients with indwelling pulmonary artery catheter (PAC) received five sequential intravenous boluses of 100 mL 4% gelatin. Cardiac output (CO) was measured with PAC before and after each bolus. Fluid responsiveness was defined as an increase in CO >10% after 500 mL fluid infusion.

Results:

Forty-seven patients were included and 35 (74.5%) patients were fluid responders. CO increasing >5.2% after a 200 mL fluid challenge (FC) provided an improved detection of fluid responsiveness, with a specificity of 80.0% and a sensitivity of 91.7%. The area under the ROC curve (AUC) was 0.93 (95% CI: 0.84–1.00, P < 0.001). Fluid administration induced a decrease in Ea from 2.23 (1.46–2.78) mmHg/mL to 1.83 (1.34–2.44) mmHg/mL (P = 0.002), especially for fluid responders in whom arterial pressure did not increase. Notably, the baseline Ea was able to detect the fluid responsiveness with an AUC of 0.74 (95% CI: 0.59–0.86, P < 0.001), whereas Ea failed to predict the pressure response to FC with an AUC of 0.50 (95% CI: 0.33–0.67, P = 0.086).

Conclusion:

In septic shock patients, a minimal volume of 200 mL 4% gelatin could reliably detect fluid responders. Fluid administration reduced Ea even when CO increased. The loss of arterial load might be the reason for patients who increased their CO without pressure responsiveness. Moreover, a high level of Ea before FC was able to predict fluid responsiveness rather than to detect the pressure responsiveness.

Trial registration:

ClinicalTrials.gov, NCT04515511

Ventriculo-arterial coupling in the intensive cardiac care unit: A non-invasive prognostic parameter

AIMS

The aim of this study was to investigate the relationship between ventriculo-arterial coupling (VAC) and in-hospital outcomes and to assess the prognostic value of VAC in critically ill patients.

METHODS AND RESULTS

A total of 329 consecutive patients (mean age 66,7 ± 15.5 years, 66.9% male) admitted to the intensive cardiac care unit of the Sandro Pertini Hospital, Rome (Italy) between January 2019 and December 2019, were included in the study. All patients underwent blood pressure measurement and non-invasive, echocardiography-derived estimates of left ventricular end-systolic elastance (Ees), arterial elastance (Ea) and VAC in a single-beat determination using the iElastance© application. In-hospital events related to acute heart failure and hypoperfusion were recorded and need for invasive ventilation, intra-aortic balloon pump, renal replacement therapy and death were considered as composite. Overall, 39 patients (11,8%) experienced in-hospital complications (group C), and 290 (88,2%) did not (group NoC). Ea and VAC were found to be significantly higher in group C than in group NoC, and a trend toward decreased Ees was observed in group C. VAC was a strong and independent predictor of in-hospital clinical outcome both at univariable and multivariable analysis adjusted for comorbidities [OR (95% CI): 1.868 (1.141-3.059); P = 0.013] and hemodynamic parameters [OR (95% CI): 1674 (1018-2755); P = 0.042].

CONCLUSION

VAC might be an additional non-invasive prognosticator of outcome in critically ill patients.

MiR-539-5p inhibits the inflammatory injury in septic H9c2 cells by regulating IRAK3

Background

MicroRNAs (miRNAs) have been confirmed to play a potential role in sepsis, but little is known about their role in sepsis-induced cardiomyopathy (SIC).

Methods

The model of septic cardiomyopathy was constructed with H9c2 cells induced by lipopolysaccharide (LPS), and the expression of miR-539-5p was detected by qRT-PCR assay. ELISA, CCK-8, EdU TUNEL analysis were performed to evaluate the role of miR-539-5p in inflammation response, viability, proliferation and apoptosis of LPS-treated H9c2 cells. Moreover, miRWalk and TargetScan prediction, and dual-luciferase reporter gene assays were carried out to predict and confirm the target of miR-539-5p. Furthermore, the effects of target on inflammation response, proliferation and apoptosis of LPS-induced H9c2 cells mediated by miR-539-5p was further explored.

Results

The expression of miR-539-5p was obviously down-regulated in LPS-induced H9c2 cells. In addition, over-expression of miR-539-5p significantly inhibited the inflammation response, promoted viability and proliferation, and suppressed apoptosis of LPS-treated H9c2 cells. Moreover, interleukin-1 receptor-associated kinase 3 (IRAK3) was verified as a target of miR-539-5p by dual-luciferase reporter gene assay. Besides, IRAK3 was highly expressed in H9c2 cells transfected with miR-539-5p inhibitor detected with qRT-PCR and western blot assays. Furthermore, over-expression of IRAK3 partially weakened the effects of miR-539-5p mimic on the inflammation response, proliferation and apoptosis of LPS-induced H9c2 cells.

Conclusions

MiR-539-5p potentially plays an important role in the pathogenesis of LPS-induced sepsis by targeting IRAK3, suggesting that miR-539-5p may be a potential new target for the treatment of LPS-induced sepsis.

MiR-702-3p inhibits the inflammatory injury in septic H9c2 cells by regulating NOD1

BACKGROUND

Cardiac insufficiency is a common complication of sepsis and septic shock and is the most common cause of death in critically ill patients. Recent studies have found that microRNAs (miRNAs) play a potential role in sepsis as markers, but little is known about their functional effects on sepsis-induced cardiomyopathy (SIC).

OBJECTIVE

This study is designed to explore the possible role and underlying mechanisms of miR-702-3p in septic cardiomyopathy.

METHODS

As expected, H9c2 cells were induced with lipopolysaccharide (LPS) to construct the model of septic cardiomyopathy. The expression of miR-702-3p was detected by qRT-PCR assay and those of IL-1β, IL-6 and TNF-α by ELISA assay. The viability, proliferation and apoptosis of LPS-treated H9c2 cells were determined by CCK-8, EdU, flow cytometry and western blot assays. Moreover, Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) was predicted and confirmed as a direct target of miR-702-3p by TargetScan, miRwalk and miRDB prediction and dual-luciferase reporter gene assays.

RESULTS

While LPS can weaken the viability of H9c2 cells, miR-702-3p enhances that of LPS-treated H9c2 cells by inhibit the expressions of TNF-α, IL-6, IL-1β. We found NOD1 is a target gene of miR-702-3p, and over-expression of NOD1 restores the inhibitory effects of miR-702-3p on the LPS-treated H9c2 cells.

CONCLUSION

MiR-702-3p played an important role in the pathogenesis of sepsis cardiomyopathy via targeting NOD1, suggesting that miR-702-3p may be a potential new target for the treatment of SIC.

Hemodynamic Monitoring in Sepsis-A Conceptual Framework of Macro- and Microcirculatory Alterations

Circulatory failure in sepsis is common and places a considerable burden on healthcare systems. It is associated with an increased likelihood of mortality, and timely recognition is a prerequisite to ensure optimum results. While there is consensus that aggressive source control, adequate antimicrobial therapy and hemodynamic management constitute crucial determinants of outcome, discussion remains about the best way to achieve each of these core principles. Sound cardiovascular support rests on tailored fluid resuscitation and vasopressor therapy. To this end, an overarching framework to improve cardiovascular dynamics has been a recurring theme in modern critical care. The object of this review is to examine the nature of one such framework that acknowledges the growing importance of adaptive hemodynamic support combining macro- and microhemodynamic variables to produce adequate tissue perfusion.

Arterial Load and Norepinephrine Are Associated With the Response of the Cardiovascular System to Fluid Expansion

Background

Fluid responsiveness has been extensively studied by using the preload prism. The arterial load might be a factor modulating the fluid responsiveness. The norepinephrine (NE) administration increases the arterial load and modifies the vascular properties. The objective of the present study was to determine the relationship between fluid responsiveness, preload, arterial load, and NE use. We hypothesized that as a preload/arterial load, NE use may affect fluid responsiveness.

Methods

The retrospective multicentered analysis of the pooled data from 446 patients monitored using the transpulmonary thermodilution before and after fluid expansion (FE) was performed. FE was standardized between intensive care units (ICUs). The comparison of patients with and without NE at the time of fluid infusion was performed. Stroke volume (SV) responsiveness was defined as an increase of more than 15% of SV following the FE. Pressure responsiveness was defined as an increase of more than 15% of mean arterial pressure (MAP) following the FE. Arterial elastance was used as a surrogate for the arterial load.

Results

A total of 244 patients were treated with NE and 202 were not treated with NE. By using the univariate analysis, arterial elastance was correlated to SV variations with FE. However, the SV variations were not associated with NE administration (26 [15; 46]% vs. 23 [10; 37]%, p = 0.12). By using the multivariate analysis, high arterial load and NE administration were associated with fluid responsiveness. The association between arterial elastance and fluid responsiveness was less important in patients treated with NE. Arterial compliance increased in the absence of NE, but it did not change in patients treated with NE (6 [−8; 19]% vs. 0 [−13; 15]%, p = 0.03). The changes in total peripheral and arterial elastance were less important in patients treated with NE (−8 [−17; 1]% vs. −11 [−20; 0]%, p < 0.05 and −10 [−19; 0]% vs. −16 [−24; 0]%, p = 0.01).

Conclusion

The arterial load and NE administration were associated with fluid responsiveness. A high arterial load was associated with fluid responsiveness. In patients treated with NE, this association was lower, and the changes of arterial load following FE seemed to be driven mainly by its resistive component.

Predictive performance of dynamic arterial elastance for arterial pressure response to fluid expansion in mechanically ventilated hypotensive adults: a systematic review and meta-analysis of observational studies

BACKGROUND

Dynamic arterial elastance (Ea_dyn) has been extensively considered as a functional parameter of arterial load. However, conflicting evidence has been obtained on the ability of Ea_dyn to predict mean arterial pressure (MAP) changes after fluid expansion. This meta-analysis sought to assess the predictive performance of Ea_dyn for the MAP response to fluid expansion in mechanically ventilated hypotensive patients.

METHODS

We systematically searched electronic databases through November 28, 2020, to retrieve studies that evaluated the association between Ea_dyn and fluid expansion-induced MAP increases in mechanically ventilated hypotensive adults. Given the diverse threshold value of Ea_dyn among the studies, we only reported the area under the hierarchical summary receiver operating characteristic curve (AUHSROC) as the primary measure of diagnostic accuracy.

RESULTS

Eight observational studies that included 323 patients with 361 fluid expansions met the eligibility criteria. The results showed that Ea_dyn was a good predictor of MAP increases in response to fluid expansion, with an AUHSROC of 0.92 [95% confidence interval (CI) 0.89 to 0.94]. Six studies reported the cut-off value of Ea_dyn, which ranged from 0.65 to 0.89. The cut-off value of Ea_dyn was nearly conically symmetrical, most data were centred between 0.7 and 0.8, and the mean and median values were 0.77 and 0.75, respectively. The subgroup analyses indicated that the AUHSROC was slightly higher in the intensive care unit (ICU) patients (0.96; 95% CI 0.94 to 0.98) but lower in the surgical patients in the operating room (0.72; 95% CI 0.67 to 0.75). The results indicated that the fluid type and measurement technique might not affect the diagnostic accuracy of Ea_dyn. Moreover, the AUHSROC for the sensitivity analysis of prospective studies was comparable to that in the primary analysis.

CONCLUSIONS

Ea_dyn exhibits good performance for predicting MAP increases in response to fluid expansion in mechanically ventilated hypotensive adults, especially in the ICU setting.

Pathophysiology of cardiogenic shock

PURPOSE OF REVIEW

We describe the pathophysiology of cardiogenic shock (CS), from the main pathways to the inflammatory mechanisms and the proteomic features.

RECENT FINDINGS

Although the classical pathophysiological pathways underlying CS, namely reduced organ perfusion due to inadequate cardiac output and peripheral vasoconstriction, have been well-established for a long time, the role of macro-and micro-hemodynamics in the magnitude of the disease and its prognosis has been investigated extensively only over the last few years. Moreover, to complete the complex picture of CS pathophysiology, the study of cytokine cascade, inflammation, and proteomic analysis has been addressed recently.

SUMMARY

Understanding the pathophysiology of CS is important to treat it optimally.

Association of fluid balance with mortality in sepsis is modified by admission hemoglobin levels: A large database study

Purpose

Sepsis involves a dysregulated inflammatory response to infection that leads to organ dysfunction. Early fluid resuscitation has been advocated by the Surviving Sepsis Campaign guidelines. However, recent studies have shown that a positive fluid balance is associated with increased mortality in septic patients. We investigated if haemoglobin levels on admission to the intensive care unit (ICU) could modify the association of fluid balance with mortality in patients with sepsis. We hypothesized that with increasing fluid balance, patients with moderate anemia (hemoglobin 7-10g/dL) would have poorer outcomes compared to those without moderate anemia (hemoglobin >10g/dL).

Materials and methods

This retrospective study utilized the Medical Information Mart for Intensive Care-III (MIMIC-III) database. Patients with sepsis, as identified by the International Classification of Diseases, 9th, Clinical Modification codes, were studied. Patients were stratified into those with and without moderate anemia at ICU admission. We investigated the influence of fluid balance measured within 24 hours of ICU admission on 28-day mortality for both patient groups using multivariable logistic regression models. Subgroup and sensitivity analyses were conducted.

Results

8,132 patients (median age 68.6 years, interquartile range 55.1–79.8 years; 52.8% female) were included. Increasing fluid balance (in L) was associated with a significantly decreased risk of 28-day mortality in patients without moderate anemia (OR 0.91, 95%CI 0.84–0.97, p = 0.005, at 6-hour). Conversely, increasing fluid balance was associated with a significantly increased risk of 28-day mortality in patients with moderate anemia (OR 1.05, 95% CI 1.01–1.1, p = 0.022, at 24-hour). Interaction analyses showed that mortality was highest when haemoglobin decreased in patients with moderate anemia who had the most positive fluid balance. Multiple subgroups and sensitivity analyses yielded consistent results.

Conclusions

In septic patients admitted to ICU, admission hemoglobin levels modified the association between fluid balance and mortality and are an important consideration for future fluid therapy trials.

Prophylactic Norepinephrine Infusion Reduces Postoperative Complications and Hospitalization Time in Elderly Patients Undergoing Posterior Lumbar Spinal Fusion

This single-center prospective randomized controlled trial explores the effect of prophylactic norepinephrine infusion on the incidence of complications and hospitalization time in elderly patients (60-85 years old) undergoing posterior lumbar spinal fusion. In total, 129 elderly patients were randomized into two groups: a group that received norepinephrine during general anesthesia and a control group not receiving norepinephrine. The primary outcomes were in-hospital complications and 90-day postoperative complications and hospitalization time. The results show that in-hospital complications occurred in 24 of 60 patients (40%) in the control group versus 11 of 60 patients (18.3%) in the norepinephrine group (RR, 2.182; 95% CI, 1.177–4.045; P = 0.015). Cardiac events occurred significantly more frequently in the control than in the norepinephrine group. Total number of patients experiencing complications within 90 days postoperatively was lower in the norepinephrine (11 of 60; 18.3%) than in the control group (26 of 60; 43.3%; RR, 2.364; 95% CI, 1.288–4.339; P = 0.005). The median length of hospital stay was 17 days (11–27) in the control group and 15 days (10– 23) in the norepinephrine group (P = 0.01). The secondary outcomes were serum levels of syndecan-1, hyaluronic acid, heparan sulfate, and brain natriuretic peptide. Logistic regression analysis is used to describe the relationship between selected independent variables and in-hospital complications. Intraoperative total fluid, crystalloid, and colloid volumes were significantly higher in the control than in the norepinephrine group. The patients in the norepinephrine group had a higher MAP but a lower heart rate than those in the control group after the induction of anesthesia and intraoperatively. Syndecan-1, hyaluronic acid, and heparan sulfate serum levels showed a different course in the two groups. In conclusion, prophylactic norepinephrine infusion during posterior lumbar spinal fusion is preferable for elderly patients undergoing lumbar spinal fusion under general anesthesia. It can reduce postoperative complications and hospitalization time by reducing the injury to the vascular endothelium. This trial is registered with Clinical Trial Registration http://www.chictr.org.cn/showproj.aspx?proj=33660, identifier ChiCTR-1900021309.

Dynamic Arterial Elastance Is Associated With the Vascular Waterfall in Patients Treated With Norepinephrine: An Observational Study

Introduction: It has been suggested that dynamic arterial elastance (Ea_dyn) can predict decreases in arterial pressure in response to changing norepinephrine levels. The objective of this study was to determine whether Ea_dyn is correlated with determinants of the vascular waterfall [critical closing pressure (CCP) and systemic arterial resistance (SARi)] in patients treated with norepinephrine.

Materials and Methods: Patients treated with norepinephrine for vasoplegia following cardiac surgery were studied. Vascular and flow parameters were recorded immediately before the norepinephrine infusion and then again once hemodynamic parameters had been stable for 15 min. The primary outcomes were Ea_dyn and its associations with CCP and SARi. The secondary outcomes were the associations between Ea_dyn and vascular/flow parameters.

Results: At baseline, all patients were hypotensive with Ea_dyn of 0.93 [0.47;1.27]. Norepinephrine increased the arterial blood pressure, cardiac index, CCP, total peripheral resistance (TPRi), arterial elastance, and ventricular elastance and decreased Ea_dyn [0.40 (0.30;0.60)] and SARi. Ea_dyn was significantly associated with arterial compliance (C_A), CCP, and TPRi (p < 0.05).

Conclusion: In patients with vasoplegic syndrome, Ea_dyn was correlated with determinants of the vascular waterfall. Ea_dyn is an easy-to-read functional index of arterial load that can be used to assess the patient’s macro/microcirculatory status.

Clinical Trial Registration:ClinicalTrials.gov #NCT03478709.

Multivariable haemodynamic approach to predict the fluid challenge response: A multicentre cohort study

BACKGROUND

Beat-to-beat stroke volume (SV) results from the interplay between left ventricular function and arterial load. Fluid challenge induces time-dependent responses in cardiac performance and peripheral vascular and capillary characteristics.

OBJECTIVE

To assess whether analysis of the determinants of the haemodynamic response during fluid challenge can predict the final response at 10 and 30 min.

DESIGN

Observational multicentric cohort study.

SETTING

Three university ICUs.

PATIENTS

85 ICU patients with acute circulatory failure diagnosed within the first 48 h of admission.

INTERVENTION(S)

The fluid challenge consisted of 500 ml of Ringer's solution infused over 10 min. A SV index increase at least 10% indicated fluid responsiveness.

MAIN OUTCOME MEASURES

The SV, pulse pressure variation (PPV), arterial elastance, the systolic-dicrotic pressure difference (SAP-Pdic) and cardiac cycle efficiency (CCE) were measured at baseline, 1, 2, 3, 4, 5, 10, 15 and 30 min after the start of the fluid challenge. All haemodynamic data were submitted to a univariable logistic regression model and a multivariable analysis was then performed using the significant variables given by univariable analysis.

RESULTS

The multivariable model including baseline PPV, and the changes of arterial elastance at 1 min and of the CCE and SAP-Pdic at 5 min when compared with their baseline values, correctly classified 80.5% of responders and 90.7% of nonresponders at 10 min. For the response 30 min after starting the fluid challenge, the model, including the changes of PPV, CCE, SAP-Pdic at 5 min and of arterial elastance at 10 min compared with their baseline values, correctly identified 93.3% of responders and 91.4% of nonresponders.

CONCLUSION

In a selection of mixed ICU patients, a statistical model based on a multivariable analysis of the changes of PPV, CCE, arterial elastance and SAP-Pdic, with respect to baseline values, reliably predicts both the early and the late response to a standardised fluid challenge.

TRIAL REGISTRATION

ACTRN12617000076370.

Effect of norepinephrine challenge on cardiovascular determinants assessed using a mathematical model in septic shock: a physiological study

BACKGROUND

The present study investigated the cardiovascular determinants of cardiac output (CO), mean systemic filling pressure analogue (Pmsa) derived by Geoffrey Parkin, efficiency of heart (Eh) and related parameters to a norepinephrine (NE) challenge [an increase of 10 mmHg mean arterial pressure (MAP) by NE] in septic shock patients using of a mathematical model.

METHODS

Twenty-seven septic shock patients with pulse index continuous cardiac output (PiCCO) monitoring were enrolled. These patients required NE to maintain an individualized MAP for organ perfusion after early fluid resuscitation based on their clinical condition. NE was decreased to obtain a decrease of 10 mmHg from base MAP (MAP-10mmHg), and the NE doses were adjusted to return MAP to baseline (MAPbase) and produce an increase of 10 mmHg from MAPbase (MAP+10mmHg). Two NE challenge episodes were analyzed for each patient: from MAP-10mmHg to MAPbase and from MAPbase to MAP+10mmHg. The Pmsa, pressure gradient for venous return (PGvr), and Eh (PGvr relative to Pmsa) were estimated using a mathematical model for the three MAP levels (MAP-10mmHg, MAPbase and MAP+10mmHg).

RESULTS

A total of 54 episodes of NE challenges were obtained in 27 patients. Significant and consistent increases were observed in the central venous pressure (CVP), Pmsa, and PGvr in response during the NE titration. ΔCO negatively and significantly correlated with ΔCVP (r=-0.722, P<0.0001), ΔPmsa (r=-0.549, P<0.0001), ΔResistance of venous return (Rvr) (r=-0.597, P<0.0001), and ΔResistance of systemic vascular beds (Rsys) (r=-0.597, P<0.0001). Episodes of decreasing CO/Eh were associated with a higher ΔCVP than the CO/Eh-increasing episodes. The area under the curve (AUC) of ΔCVP to predict decreased CO by the incremental NE was 0.86, and the AUC of ΔCVP to predict decreased Eh was 0.94. A cutoff of ΔCVP >1.5 mmHg for detecting decreased CO resulted in a sensitivity of 75% and a specificity of 94.1%. A cutoff of ΔCVP >1.5 mmHg for detecting decreased Eh resulted in a sensitivity of 64.3% and a specificity of 100%.

CONCLUSIONS

There were a highly divergent response in Eh and CO to afterload challenge episodes of an NE-induced 10mmHg increase in MAP. An increase in CVP may be an early alarm to identify the reduction in CO/Eh during an NE-induced increase of MAP.

Mortality prediction using a novel combination of biomarkers in the first day of sepsis in intensive care units

Early identification of infection severity and organ dysfunction is crucial in improving outcomes of patients with sepsis. We aimed to develop a new combination of blood-based biomarkers that can early predict 28-day mortality in patients with sepsis or septic shock. We enrolled 66 patients with sepsis or septic shock and compared 14 blood-based biomarkers in the first 24 h after ICU admission. The serum levels of interleukin-6 (IL-6) (median 217.6 vs. 4809.0 pg/ml, P = 0.001), lactate (median 2.4 vs. 6.3 mmol/L, P = 0.014), N-terminal prohormone of brain natriuretic peptide (NT-proBNP) (median 1596.5 vs. 32,905.3 ng/ml, P < 0.001), prothrombin time (PT) (median 15.6 vs. 20.1 s, P = 0.030), activated partial thrombin time (APTT) (median 45.1 vs. 59.0 s, P = 0.026), and international normalized ratio (INR) (median 1.3 vs. 1.8, P < 0.001) were significantly lower in the survivor group. IL-6, NT-proBNP, and INR provided the best individual performance in predicting 28-day mortality of patients with sepsis or septic shock. Furthermore, the combination of these three biomarkers achieved better predictive performance (AUC 0.890, P < 0.001) than conventional scoring systems. In summary, the combination of IL-6, NT-proBNP, and INR may serve as a potential predictor of 28-day mortality in critically ill patients with sepsis or septic shock.

How to assess ventriculoarterial coupling in sepsis

PURPOSE OF REVIEW

We will highlight the role of ventriculoarterial coupling in the pathophysiology of sepsis and how to assess it.

RECENT FINDINGS

Most septic patients show a ventriculoarterial uncoupling at the time of diagnosis with arterial elastance (Ea) greater than left ventricle (LV) end-systolic elastance (Ees), often despite arterial hypotension. Ventriculoarterial coupling levels predict the cardiovascular response to resuscitation in this heterogeneously responding population.

SUMMARY

Ventriculoarterial coupling is quantified as the ratio of Ea to Ees. The efficiency of the cardiovascular function is optimal when Ea/Ees is near one. When the hydraulic load of the arterial system is excessive either from increased vasomotor tone, decreased LV contractility or both, Ea/Ees becomes greater than 1 (i.e. ventriculoarterial decoupling), and cardiac efficiency decreases leading to heart failure, loss of volume responsiveness, and if sustained, increased mortality. Noninvasive echocardiographic techniques when linked with arterial pressure monitoring allow for the bedside estimates of both Ea and Ees. Studies using this approach have documented the key role ventriculoarterial coupling has defining initial cardiovascular state, response to therapy and outcome from critical illness. Sequential monitoring of ventriculoarterial coupling at the bedside offers a unique opportunity to assess relevant cardiovascular determinants in septic patients requiring resuscitation.

Prediction of hypotension events with physiologic vital sign signatures in the intensive care unit

BACKGROUND

Even brief hypotension is associated with increased morbidity and mortality. We developed a machine learning model to predict the initial hypotension event among intensive care unit (ICU) patients and designed an alert system for bedside implementation.

MATERIALS AND METHODS

From the Medical Information Mart for Intensive Care III (MIMIC-3) dataset, minute-by-minute vital signs were extracted. A hypotension event was defined as at least five measurements within a 10-min period of systolic blood pressure ≤ 90 mmHg and mean arterial pressure ≤ 60 mmHg. Using time series data from 30-min overlapping time windows, a random forest (RF) classifier was used to predict risk of hypotension every minute. Chronologically, the first half of extracted data was used to train the model, and the second half was used to validate the trained model. The model's performance was measured with area under the receiver operating characteristic curve (AUROC) and area under the precision recall curve (AUPRC). Hypotension alerts were generated using risk score time series, a stacked RF model. A lockout time were applied for real-life implementation.

RESULTS

We identified 1307 subjects (1580 ICU stays) as the hypotension group and 1619 subjects (2279 ICU stays) as the non-hypotension group. The RF model showed AUROC of 0.93 and 0.88 at 15 and 60 min, respectively, before hypotension, and AUPRC of 0.77 at 60 min before. Risk score trajectories revealed 80% and > 60% of hypotension predicted at 15 and 60 min before the hypotension, respectively. The stacked model with 15-min lockout produced on average 0.79 alerts/subject/hour (sensitivity 92.4%).

CONCLUSION

Clinically significant hypotension events in the ICU can be predicted at least 1 h before the initial hypotension episode. With a highly sensitive and reliable practical alert system, a vast majority of future hypotension could be captured, suggesting potential real-life utility.

The inspiration hold maneuver is a reliable method to assess mean systemic filling pressure but its clinical value remains unclear

Background

The upstream pressure for venous return (VR) is considered to be a combined conceptual blood pressure of the systemic vessels: the mean systemic filling pressure (MSFP). The relevance of estimating the MSFP during dynamic changes of the circulation at the bedside is controversial. Herein, we studied the effect of high ventilatory pressures on the relationship between VR and central venous pressure (CVP).

Methods

In 9 healthy pigs under anaesthesia and mechanically ventilated, MSFP was estimated from extrapolated VR versus CVP relationships during inspiratory hold maneuvers (IHMs) with different levels of ventilatory pressure (Pvent). MSFP was measure 3 times per animal during euvolemia and hypovolemia. Hypovolemia was induced by bleeding with 10 mL/kg. The estimated MSFP values were compared to the blood pressure recording after induced ventricle fibrillation (i.e., mean circulatory filling pressure).

Results

Our results revealed a strong linear correlation between VR and CVP [R2 of 0.92 (range, 0.67–0.99)], during IHMs with different levels of Pvent. Volume status significantly alters the resulting MSFP, 20±1 and 16±2 mmHg for euvolemia and hypovolemia respectively. This estimation of the MSFP was strongly correlated—but not interchangeable—to the blood pressure recording after induced ventricle fibrillation (R2=0.8 and P=0.045).

Conclusions

In conclusion, we showed a strong linear correlation between VR and CVP—when applying IHMs with high levels of Pvent—however the clinical applicability of this method to guide volume therapy in its current form is improbable.

Dynamic Arterial Elastance During Experimental Endotoxic Septic Shock: A Potential Marker of Cardiovascular Efficiency

Dynamic arterial elastance (Ea_dyn), the ratio between pulse pressure variation (PPV) and stroke volume variation (SVV), has been suggested as a dynamic parameter relating pressure and flow. We aimed to determine the effects of endotoxic septic shock and hemodynamic resuscitation on Ea_dyn in an experimental study in 18 New Zealand rabbits. Animals received placebo (SHAM, n = 6) or intravenous lipopolysaccharide (E. Coli 055:B5, 1 mg⋅kg ^{- 1}) with or without (EDX-R, n = 6; EDX, n = 6) hemodynamic resuscitation (fluid bolus of 20 ml⋅kg ^{- 1} and norepinephrine for restoring mean arterial pressure). Continuous arterial pressure and aortic blood flow measurements were obtained simultaneously. Cardiovascular efficiency was evaluated by the oscillatory power fraction [%Osc: oscillatory work/left ventricular (LV) total work] and the energy efficiency ratio (EER = LV total work/cardiac output). Ea_dyn increased in septic animals (from 0.73 to 1.70; p = 0.012) and dropped after hemodynamic resuscitation. Ea_dyn was related with the %Osc and EER [estimates: -0.101 (-0.137 to -0.064) and -9.494 (-11.964 to -7.024); p < 0.001, respectively]. So, the higher the Ea_dyn, the better the cardiovascular efficiency (lower %Osc and EER). Sepsis resulted in a reduced %Osc and EER, reflecting a better cardiovascular efficiency that was tracked by Ea_dyn. Ea_dyn could be a potential index of cardiovascular efficiency during septic shock.

Management of cardiovascular insufficiency in ICU: the BEAT approach

A large number of patients admitted to ICU display hemodynamic deterioration at some time during their stay. The management of acute hemodynamic derangement of any cause can be difficult and has to be accomplished quickly and correctly as delayed and inappropriate resuscitation treatments carry increased mortality. Cardiovascular insufficiency shows end-organ hypoperfusion-associated dysfunction, thus decreasing level of consciousness, falling urine output, ileus, new onset tachypnea and the presence of skin mottling are important clinical clues to cardiovascular deterioration and should be promptly looked for and if detected alert the bedside clinician that further assessment and potentially treatment is necessary. Although measures of serum lactate are useful to document the presence of tissue hypoperfusion, they are non-specific in defining its etiology. In a patient with acute hemodynamic instability, we propose a step-by-step approach as follows: 1) rapid initial ultrasound assessment of heart function; 2) pathophysiological understanding of heart and circulation interaction; 3) functional hemodynamic monitoring; and 4) treatment. We named such approach BEAT, which stands for: browse the heart, measure the elastances, assess volume status, and treat. Combining bedside echocardiography, including the evaluation of the interaction between the heart and the circulation, with FHM offers the opportunity to personalize the hemodynamic management to the specific requirements.