Detailing the cardiovascular profile in shock patients

The Outcomes of the Initial Misclassification of Undifferentiated Hypotension in the Emergency Department: A Prospective Observational Study

Background: Managing shock, a life-threatening emergency, is challenging. The influence of the initial misclassification of undifferentiated hypotension (UH) in the emergency department (ED) on patients' outcomes remains uninvestigated. The aim of this study was to investigate whether the initial misclassification of UH in the ED affects patients' clinical outcomes. Materials and Methods: This prospective observational study enrolled 270 non-traumatic adult patients with UH who had visited the ED of National Taiwan University Hospital between July 2020 and January 2022. The patients were divided into same-diagnosis and different-diagnosis groups, depending on the consistency between the initial and final classifications of shock. The outcome was survival to discharge. The clinical variables, management, and outcomes were compared between the groups. Results: A total of 39 of 270 patients (14.4%) were in the different-diagnosis group. Most misclassified patients were initially diagnosed as having hypovolemic shock (HS, n = 29) but finally diagnosed as having distributive shock (DS, n = 28) or cardiogenic shock (n = 1). When compared with the same-diagnosis group, the different-diagnosis group had higher hospitalization (94.9% vs. 81.4%, p = 0.023) but lower ED discharge (5.1% vs. 16.5%, p = 0.046) rates. Logistic regression analysis showed that the HS initially diagnosed was associated with an increased risk of misclassification (odds ratio [OR] = 14.731, 95% confidence interval [CI] = 3.572-60.749, p < 0.001). However, the survival to discharge did not differ between the two groups. DS, when finally diagnosed instead of the initial misclassification, was associated with in-hospital mortality (OR = 0.317, 95%CI = 0.124-0.810, p = 0.016). Conclusions: The misclassification of UH in the ED is not rare, particularly in patients with DS, who are likely to be initially misdiagnosed with HS. Although misclassification may increase hospitalization and decrease ED discharge, it does not affect survival to discharge.

Precision fluid and vasoactive drug therapy for critically ill patients

There are several clinical practice guidelines concerning the use of fluid and vasoactive drug therapies in critically ill adult patients, but the recommendations in these guidelines are often based on low-quality evidence. Further, some were compiled prior to the publication of landmark clinical trials, particularly in the comparison of balanced crystalloid and normal saline. An important consideration in the treatment of critically ill patients is the application of precision medicine to provide the most effective care to groups of patients most likely to benefit from the therapy. Although not currently widely integrated into these practice guidelines, the utility of precision medicine in critical illness is a recognized research priority for fluid and vasoactive therapy management. The purpose of this narrative review was to illustrate the evaluation and challenges of providing precision fluid and vasoactive therapies to adult critically ill patients. The review includes a discussion of important investigations published after the release of currently available clinical practice guidelines to provide insight into how recommendations and research priorities may change future guidelines and bedside care for critically ill patients.

Prevalence of systemic venous congestion assessed by Venous Excess Ultrasound Grading System (VExUS) and association with acute kidney injury in a general ICU cohort: a prospective multicentric study

BACKGROUND

The importance of assessing venous congestion in ICU patients is widely acknowledged, but its study is hampered by the lack of a practical evaluation tool. The Venous Excess Ultrasound Grading System (VExUS), based on a semi-quantitative combined ultrasound assessment, has been associated with acute kidney injury (AKI) in cardiac ICU patients. The objectives of this study were to assess the prevalence of congestion using VExUS in general ICU patients, and to evaluate the association between VExUS, AKI and death.

METHODS

This prospective, observational study included adult patients within 24 h of ICU admission. VExUS and hemodynamic parameters were measured four times during the ICU stay: within 24 h of ICU admission, after day 1 (between 24 and 48 h), after day 2 (between 48 and 72 h), and last day of ICU stay. The prevalence of AKI during the first week in ICU and 28-day mortality were assessed.

RESULTS

Among the 145 patients included, the percentage of patients with a VExUS score of 2 (moderate congestion) and 3 (severe congestion) was 16% and 6%, respectively. The prevalence did not change over the study period. There was no significant association between admission VExUS scores and AKI (p = 0.136) or 28-day mortality (p = 0.594). Admission VExUS ≥ 2 was not associated with AKI (OR 0.499, CI_95% 0.21-1.17, p = 0.109) nor 28-day mortality (OR 0.75, CI_95% 0.2-2.8, p = 0.669). The results were similar for VExUS scores measured at day 1 and day 2.

CONCLUSIONS

In general ICU cohort the prevalence of moderate to severe venous congestion was low. Early assessment of systemic venous congestion using VExUS scores was not associated with the development of AKI or with 28-day mortality.

How can assessing hemodynamics help to assess volume status?

In critically ill patients, fluid infusion is aimed at increasing cardiac output and tissue perfusion. However, it may contribute to fluid overload which may be harmful. Thus, volume status, risks and potential efficacy of fluid administration and/or removal should be carefully evaluated, and monitoring techniques help for this purpose. Central venous pressure is a marker of right ventricular preload. Very low values indicate hypovolemia, while extremely high values suggest fluid harmfulness. The pulmonary artery catheter enables a comprehensive assessment of the hemodynamic profile and is particularly useful for indicating the risk of pulmonary oedema through the pulmonary artery occlusion pressure. Besides cardiac output and preload, transpulmonary thermodilution measures extravascular lung water, which reflects the extent of lung flooding and assesses the risk of fluid infusion. Echocardiography estimates the volume status through intravascular volumes and pressures. Finally, lung ultrasound estimates lung edema. Guided by these variables, the decision to infuse fluid should first consider specific triggers, such as signs of tissue hypoperfusion. Second, benefits and risks of fluid infusion should be weighted. Thereafter, fluid responsiveness should be assessed. Monitoring techniques help for this purpose, especially by providing real time and precise measurements of cardiac output. When decided, fluid resuscitation should be performed through fluid challenges, the effects of which should be assessed through critical endpoints including cardiac output. This comprehensive evaluation of the risk, benefits and efficacy of fluid infusion helps to individualize fluid management, which should be preferred over a fixed restrictive or liberal strategy.

The use of metaraminol as a vasopressor in critically unwell patients: a narrative review and a survey of UK practice

Background

Major international guidelines state that norepinephrine should be used as the first-line vasopressor to achieve adequate blood pressure in patients with hypotension or shock. However, recent observational studies report that in the United Kingdom and Australia, metaraminol is often used as second line medication for cardiovascular support.

Aim of the study

The aim of this study was to carry out a systematic review of metaraminol use for management of shock in critically unwell patients and carry out a survey evaluating whether UK critical care units use metaraminol and under which circumstances.

Methods

A systematic review literature search was conducted. A short telephone survey consisting of 6 questions regarding metaraminol use was conducted across 30 UK critical care units which included a mix of tertiary and district general intensive care units.

Results

Twenty-six of thirty contacted centres responded to our survey. Metaraminol was used in 88% of them in various settings and circumstances (emergency department, theatres, medical emergencies on medical wards), with 67% reporting use of metaraminol infusions in the critical care setting. The systematic literature review revealed several case reports and only two studies conducted in the last 20 years investigating the effect of metaraminol as a stand-alone vasopressor. Both studies focused on different aspects of metaraminol use and the data was incomparable, hence we decided not to perform a meta-analysis.

Conclusions

Metaraminol is widely used as a vasopressor inside and outside of the critical care setting in the UK despite limited evidence supporting its safety and efficacy for treating shock. Further service evaluation, observational studies and prospective randomised controlled trials are warranted to validate the role and safety profile of metaraminol in the treatment of the critically unwell patient.

Ventriculo-Arterial Coupling Is Associated With Oxygen Consumption and Tissue Perfusion in Acute Circulatory Failure

Introduction

The determination of ventriculo-arterial coupling is gaining an increasing role in cardiovascular and sport medicine. However, its relevance in critically ill patients is still under investigation. In this study we measured the association between ventriculo-arterial coupling and oxygen consumption (VO2) response after hemodynamic interventions in cardiac surgery patients with acute circulatory instability.

Material and Methods

Sixty-one cardio-thoracic ICU patients (67 ± 12 years, 80% men) who received hemodynamic therapeutic interventions (fluid challenge or norepinephrine infusion) were included. Arterial pressure, cardiac output, heart rate, arterial (EA), and ventricular elastances (EV), total indexed peripheral resistances were assessed before and after hemodynamic interventions. VO2 responsiveness was defined as VO2 increase &gt;15% following the hemodynamic intervention. Ventriculo-arterial coupling was assessed measuring the EA/EV ratio by echocardiography. The left ventricle stroke work to pressure volume area ratio (SW/PVA) was also calculated.

Results

In the overall cohort, 24 patients (39%) were VO2 responders, and 48 patients had high ventriculo-arterial (EA/EV) coupling ratio with a median value of 1.9 (1.6–2.4). Most of those patients were classified as VO2 responders (28 of 31 patients, p = 0.031). Changes in VO2 were correlated with those of indexed total peripheral resistances, EA, EA/EV and cardiac output. EA/EV ratio predicted VO2 increase with an AUC of 0.76 [95% CI: 0.62–0.87]; p = 0.001. In principal component analyses, EA/EV and SW/PVA ratios were independently associated (p &lt; 0.05) with VO2 response following interventions.

Conclusions

VO2 responders were characterized by baseline high ventriculo-arterial coupling ratio due to high EA and low EV. Baseline EA/EV and SW/PVA ratios were associated with VO2 changes independently of the hemodynamic intervention used. These results underline the pathophysiological significance of measuring ventriculo-arterial coupling in patients with hemodynamic instability, as a potential therapeutic target.

Efficacy of Veno-Arterial Extracorporeal Life Support in Adult Patients with Refractory Cardiogenic Shock

Background

This study aimed to describe the efficacy of veno-arterial extracorporeal life support (VA-ECLS) through early lactate clearance and pH restoration and assess the potential association with 30-day survival following hospital discharge.

Methods

Data of patients receiving VA-ECLS for at least 24 h were retrospectively compiled. Blood lactate levels, liver enzymes, and kidney parameters prior to VA-ECLS initiation and at 2, 8, 14, 20, and 26 h of support had been recorded as part of clinical care. The primary outcome was 30-day survival.

Results

Of 77 patients who underwent VA-ECLS for refractory cardiogenic shock, 44.2% survived. For all non-survivors, ECLS was initiated after eight hours (p = .008). Blood pH was significantly higher in survivors compared to non-survivors at all time points except for pre-ECLS. Lactate levels were significantly lower in survivors (median range 1.95-4.70 vs 2.90-6.70 mmol/L for survivors vs non-survivors, respectively). Univariate and multivariate analyses indicated that blood pH at 24 h (OR 0.045, 95% CI: 0.005-0.448 for pH <7.35, p = .045) and lactate concentration pre-ECLS (OR 0.743, 95% CI: 0.590-0.936, p = .012) were reliable predictors for 30-day survival. Further, ischemic cardiogenic shock as ECLS indication showed 36.2% less lactate clearance compared to patients with other indications such as arrhythmia, postcardiotomy, and ECPR.

Conclusion

ECLS showed to be an effective treatment in reducing blood lactate levels in patients suffering from refractory cardiogenic shock in which the outcome is influenced by the initial lactate level and pH in the early phase of the intervention.

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.

The Use of Central Venous to Arterial Carbon Dioxide Tension Gap for Outcome Prediction in Critically Ill Patients: A Systematic Review and Meta-Analysis

OBJECTIVES

In this systematic review and meta-analysis, we assessed whether a high CO2 gap predicts mortality in adult critically ill patients with circulatory shock.

DATA SOURCES

A systematic search of MEDLINE and EMBASE electronic databases from inception to October 2019.

STUDY SELECTION

Studies from adult (age ≥ 18 yr) ICU patients with shock reporting CO2 gap and outcomes of interest. Case reports and conference abstracts were excluded.

DATA EXTRACTION

Data extraction and study quality assessment were performed independently in duplicate.

DATA SYNTHESIS

We used the Newcastle-Ottawa Scale to assess methodological study quality. Effect sizes were pooled using a random-effects model. The primary outcome was mortality (28 d and hospital). Secondary outcomes were ICU length of stay, hospital length of stay, duration of mechanical ventilation, use of renal replacement therapy, use of vasopressors and inotropes, and association with cardiac index, lactate, and central venous oxygen saturation.

CONCLUSIONS

We included 21 studies (n = 2,155 patients) from medical (n = 925), cardiovascular (n = 685), surgical (n = 483), and mixed (n = 62) ICUs. A high CO2 gap was associated with increased mortality (odds ratio, 2.22; 95% CI, 1.30-3.82; p = 0.004) in patients with shock, but only those from medical and surgical ICUs. A high CO2 gap was associated with higher lactate levels (mean difference 0.44 mmol/L; 95% CI, 0.20-0.68 mmol/L; p = 0.0004), lower cardiac index (mean difference, -0.76 L/min/m; 95% CI, -1.04 to -0.49 L/min/m; p = 0.00001), and central venous oxygen saturation (mean difference, -5.07; 95% CI, -7.78 to -2.37; p = 0.0002). A high CO2 gap was not associated with longer ICU or hospital length of stays, requirement for renal replacement therapy, longer duration of mechanical ventilation, or higher vasopressors and inotropes use. Future studies should evaluate whether resuscitation aimed at closing the CO2 gap improves mortality in shock.

An email-based survey of practice regarding hemodynamic monitoring and management in children with septic shock in China

BACKGROUND

Understanding current hemodynamic monitoring (HM) practice patterns is essential to determine education and training strategies in China. The survey was to describe the practice of HM and management in children with septic shock in China.

METHODS

We conducted an Email-based survey of members of sub-association of pediatric intensive care physicians. The questionnaire consisted of 22 questions and gathered the following information: (I) general information on the hospitals, respective ICUs and participants, (II) the availability of technical equipment and parameters of HM and (III) management simulation of septic shock in three clinical case vignettes.

RESULTS

Surveys were received from 68 institutions (87.2%) and 368 questionnaires (response-rate 45.1%) were included. Basic HM (93-100%) were reported as the most utilized parameters, followed by advanced HM which included central venous pressure (CVP) (56.0%), cardiac output (53.5%), and central venous oxygen saturation (36.7%), 61.1% (225/368) of respondents stated the utilization of non-invasive HM equipment. The factors such as ICU specialist training center (P=0.003) and more than 30 cases of septic shock per year (P=0.002) were related to the utilization of non-invasive monitoring equipment. In the simulated case vignette, 49.7% (183/368) of respondents reported performing fluid responsiveness and volume status (FR-VS) assessment. Despite differences in training centers (P=0.005) and educational backgrounds (P=0.030), FR-VS assessment was not related to the volume expansion decision.

CONCLUSIONS

There is a large variability in use advanced HM parameters, an increasing awareness and acceptance of non-invasive HM devices and a potential need for hemodynamic education and training in pediatric intensive care medicine in China.

Noninvasive Monitoring in the Intensive Care Unit

There has been considerable development in the field of noninvasive hemodynamic monitoring in recent years. Multiple devices have been proposed to assess blood pressure, cardiac output, and tissue perfusion. All have their own advantages and disadvantages and selection should be based on individual patient requirements and disease severity and adjusted according to ongoing patient evolution.

Hemodynamic monitoring in patients with venoarterial extracorporeal membrane oxygenation

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is an effective mechanical circulatory support modality that rapidly restores systemic perfusion for circulatory failure in patients. Given the huge increase in VA-ECMO use, its optimal management depends on continuous and discrete hemodynamic monitoring. This article provides an overview of VA-ECMO pathophysiology, and the current state of the art in hemodynamic monitoring in patients with VA-ECMO.

Improving the prognostic value of ∆PCO2 following cardiac surgery: a prospective pilot study

Conflicting results have been published on prognostic significance of central venous to arterial PCO₂ difference (∆PCO₂) after cardiac surgery. We compared the prognostic value of ∆PCO₂ on intensive care unit (ICU) admission to an original algorithm combining ∆PCO₂, ERO₂ and lactate to identify different risk profiles. Additionally, we described the evolution of ∆PCO₂ and its correlations with ERO₂ and lactate during the first postoperative day (POD1). In this monocentre, prospective, and pilot study, 25 patients undergoing conventional cardiac surgery were included. Central venous and arterial blood gases were collected on ICU admission and at 6, 12 and 24 h postoperatively. High ∆PCO₂ (≥ 6 mmHg) on ICU admission was found to be very frequent (64% of patients). Correlations between ∆PCO₂ and ERO₂ or lactate for POD1 values and variations were weak or non-existent. On ICU admission, a high ∆PCO₂ did not predict a prolonged ICU length of stay (LOS). Conversely, a significant increase in both ICU and hospital LOS was observed in high-risk patients identified by the algorithm: 3.5 (3.0–6.3) days versus 7.0 (6.0–8.0) days (p = 0.01) and 12.0 (8.0–15.0) versus 8.0 (8.0–9.0) days (p < 0.01), respectively. An algorithm incorporating ICU admission values of ∆PCO₂, ERO₂ and lactate defined a high-risk profile that predicted prolonged ICU and hospital stays better than ∆PCO₂ alone.

Minimizing catecholamines and optimizing perfusion

Catecholamines are used to increase cardiac output and blood pressure, aiming ultimately at restoring/improving tissue perfusion. While intuitive in its concept, this approach nevertheless implies to be effective that regional organ perfusion would increase in parallel to cardiac output or perfusion pressure and that the catecholamine does not have negative effects on the microcirculation. Inotropic agents may be considered in some conditions, but it requires prior optimization of cardiac preload. Alternative approaches would be either to minimize exposure to vasopressors, tolerating hypotension and trying to prioritize perfusion but this may be valid as long as perfusion of the organ is preserved, or to combine moderate doses of vasopressors to vasodilatory agents, especially if these are predominantly acting on the microcirculation. In this review, we will discuss the pros and cons of the use of catecholamines and alternative agents for improving tissue perfusion in septic shock.

The ratios of central venous to arterial carbon dioxide content and tension to arteriovenous oxygen content are not associated with overall anaerobic metabolism in postoperative cardiac surgery patients

Background

The aim of the present study was to evaluate the ability of the ratios of central venous to arterial carbon dioxide content and tension to arteriovenous oxygen content to predict an increase in oxygen consumption (VO₂) upon fluid challenge (FC).

Methods and results

110 patients admitted to cardiothoracic ICU and in whom the physician had decided to perform an FC (with 500 ml of Ringer's lactate solution) were included. The arterial pressure, cardiac index (Ci), and arterial and venous blood gas levels were measured before and after FC. VO₂ and CO₂-O₂ derived variables were calculated. VO₂ responders were defined as patients showing more than a 15% increase in VO₂. Of the 92 FC responders, 43 (46%) were VO₂ responders. At baseline, pCO₂ gap, C(a-v)O₂ were lower in VO₂ responders than in VO₂ non-responders, and central venous oxygen saturation (ScvO₂) was higher in VO₂ responders. FC was associated with an increase in MAP, SV, and CI in both groups. With regard to ScvO_2, FC was associated with an increase in VO₂ non-responders and a decrease in VO₂ responders. FC was associated with a decrease in pvCO₂ and pCO₂ gap in VO₂ non-responders only. The pCO₂ gap/C(a-v)O₂ ratio and C(a-v)CO₂ content /C(a-v)O₂ content ratio did not change with FC. The CO₂ gap content/C(a-v)O₂ content ratio and the C(a-v)CO₂ content /C(a-v)O₂ content ratio did not predict fluid-induced VO₂ changes (area under the curve (AUC) [95% confidence interval (CI)] = 0.52 [0.39‒0.64] and 0.53 [0.4–0.65], respectively; p = 0.757 and 0.71, respectively). ScvO₂ predicted an increase of more than 15% in the VO₂ (AUC [95%CI] = 0.67 [0.55‒0.78]; p<0.0001).

Conclusions

Our results showed that the ratios of central venous to arterial carbon dioxide content and tension to arteriovenous oxygen content were not predictive of VO₂ changes following fluid challenge in postoperative cardiac surgery patients.

Relationships Between Intraoperative Hemodynamic Parameters and Delayed Hemodynamic Recovery After Valve Deployment in Transcatheter Aortic Valve Replacement

OBJECTIVE

To determine the relationships between intraoperative hemodynamic parameters and delayed hemodynamic recovery after valve deployment and identify the predictive factors of delayed hemodynamic recovery by focusing on intraoperative hemodynamics in patients with transcatheter aortic valve replacement (TAVR).

DESIGN

A retrospective study.

SETTING

A single university hospital.

PARTICIPANTS

Sixty-four patients who underwent elective TAVR between 2015 and 2017.

INTERVENTIONS

No intervention.

MEASUREMENTS AND MAIN RESULTS

The 64 patients were divided into the following 2 groups according to the time for recovery: systolic arterial pressure exceeded 90 mmHg and central venous oxygen saturation (ScvO₂) exceeded 65%-delayed recovery (DR) (n = 36) group, and early recovery (ER) (n = 28) group. ScvO₂ in the DR group was not lower than that in the ER group after induction of anesthesia. However, ScvO₂ in the DR group gradually decreased and was lower than that in the ER group before valve deployment, despite improvement in blood pressure through the administration of vasopressor agents.

CONCLUSION

ScvO₂ monitoring during TAVR is useful to predict delayed recovery greater than 60 seconds after valve deployment in TAVR.

A shocking bike accident

CLINICAL INTRODUCTION: A man in his late 40s presented with severe chest pain and progressive dyspnoea after hitting a tree at high speed during a bike ride in the woods. On admission, the patient appeared agitated, pale and sweaty. Core temperature was 35.5°C, respiratory rate 35/min and blood pressure 90/50 mm Hg with a regular pulse at 110 beats/min. Physical examination revealed multiple sternal bruises, distended jugular veins and muffled heart sounds (figure 1A). Lactate level was 4.4 mmol/L (normal <2.0 mmol/L) and high-sensitivity cardiac troponin T 0.142 mcg/L (normal <0.005 mcg/L). An ECG and a total body CT scan were performed (figure 1B,C).heartjnl;104/20/1706/F1F1F1Figure 1(A) Multiple sternal bruises. (B) ECG on admission. (C) Thoracic CT. QUESTION  WHAT IS THE MOST LIKELY DIAGNOSIS?: Inferior myocardial infarction with right ventricular involvement.Cardiac contusion with tamponade.Commotio cordis.Aortic laceration.

Anesthesia-Associated Relative Hypovolemia: Mechanisms, Monitoring, and Treatment Considerations

Although the utility and benefits of anesthesia and analgesia are irrefutable, their practice is not void of risks. Almost all drugs that produce anesthesia endanger cardiovascular stability by producing dose-dependent impairment of cardiac function, vascular reactivity, and compensatory autoregulatory responses. Whereas anesthesia-related depression of cardiac performance and arterial vasodilation are well recognized adverse effects contributing to anesthetic risk, far less emphasis has been placed on effects impacting venous physiology and venous return. The venous circulation, containing about 65–70% of the total blood volume, is a pivotal contributor to stroke volume and cardiac output. Vasodilation, particularly venodilation, is the primary cause of relative hypovolemia produced by anesthetic drugs and is often associated with increased venous compliance, decreased venous return, and reduced response to vasoactive substances. Depending on factors such as patient status and monitoring, a state of relative hypovolemia may remain clinically undetected, with impending consequences owing to impaired oxygen delivery and tissue perfusion. Concurrent processes related to comorbidities, hypothermia, inflammation, trauma, sepsis, or other causes of hemodynamic or metabolic compromise, may further exacerbate the condition. Despite scientific and technological advances, clinical monitoring and treatment of relative hypovolemia still pose relevant challenges to the anesthesiologist. This short perspective seeks to define relative hypovolemia, describe the venous system’s role in supporting normal cardiovascular function, characterize effects of anesthetic drugs on venous physiology, and address current considerations and challenges for monitoring and treatment of relative hypovolemia, with focus on insights for future therapies.