Targeting low-normal or high-normal mean arterial pressure after cardiac arrest and resuscitation: a randomised pilot trial

The critical care literature 2022

The number of critically ill patients that present to emergency departments across the world has risen steadily for nearly two decades. Despite a decrease in initial emergency department (ED) volumes early in the COVID-19 pandemic, the proportion of critically ill patients is now higher than pre-pandemic levels [1]. The emergency physician (EP) is often the first physician to evaluate and resuscitate a critically ill patient. In addition, EPs are frequently tasked with providing critical care long beyond the initial resuscitation. Prolonged boarding of critically ill patients in the ED is associated with increased duration of mechanical ventilation, increased intensive care unit (ICU) length of stay, increased hospital length of stay, increased medication-related adverse events, and increased in-hospital, 30-day, and 90-day mortality [2-4]. Given the continued increase in critically ill patients along with the increases in boarding critically ill patients in the ED, it is imperative for the EP to be knowledgeable about recent literature in resuscitation and critical care medicine, so that critically ill patients continue to receive evidence-based care. This review summarizes important articles published in 2022 that pertain to the resuscitation and management of select critically ill ED patients. These articles have been selected based on the authors review of key critical care, resuscitation, emergency medicine, and medicine journals and their opinion of the importance of study findings as it pertains to the care of the critically ill ED patient. Topics covered in this article include cardiac arrest, post-cardiac arrest care, rapid sequence intubation, mechanical ventilation, fluid resuscitation, and sepsis.

Emergent Management of Hypoxic-Ischemic Brain Injury

OBJECTIVE

This article outlines interventions used to improve outcomes for patients with hypoxic-ischemic brain injury after cardiac arrest.

LATEST DEVELOPMENTS

Emergent management of patients after cardiac arrest requires prevention and treatment of primary and secondary brain injury. Primary brain injury is minimized by excellent initial resuscitative efforts. Secondary brain injury prevention requires the detection and correction of many pathophysiologic processes that may develop in the hours to days after the initial arrest. Key physiologic parameters important to secondary brain injury prevention include optimization of mean arterial pressure, cerebral perfusion, oxygenation and ventilation, intracranial pressure, temperature, and cortical hyperexcitability. This article outlines recent data regarding the treatment and prevention of secondary brain injury. Different patients likely benefit from different treatment strategies, so an individualized approach to treatment and prevention of secondary brain injury is advisable. Clinicians must use multimodal sources of data to prognosticate outcomes after cardiac arrest while recognizing that all prognostic tools have shortcomings.

ESSENTIAL POINTS

Neurologists should be involved in the postarrest care of patients with hypoxic-ischemic brain injury to improve their outcomes. Postarrest care requires nuanced and patient-centered approaches to the prevention and treatment of primary and secondary brain injury and neuroprognostication.

Randomized controlled trials in resuscitation

Randomized controlled trials (RCTs) are a gold standard in research and crucial to our understanding of resuscitation science. Many trials in resuscitation have had neutral findings, questioning which treatments are effective in cardiac resuscitation. While it is possible than many interventions do not improve patient outcomes, it is also possible that the large proportion of neutral findings are partially due to design limitations. RCTs can be challenging to implement, and require extensive resources, time, and funding. In addition, conducting RCTs in the out-of-hospital setting provides unique challenges that must be considered for a successful trial. This article will outline many important aspects of conducting trials in resuscitation in the out-of-hospital setting including patient and outcome selection, trial design, and statistical analysis.

Survival, but not the severity of hypoxic-ischemic encephalopathy, is associated with higher mean arterial blood pressure after cardiac arrest: a retrospective cohort study

Background

This study investigates the association between the mean arterial blood pressure (MAP), vasopressor requirement, and severity of hypoxic-ischemic encephalopathy (HIE) after cardiac arrest (CA).

Methods

Between 2008 and 2017, we retrospectively analyzed the MAP 200 h after CA and quantified the vasopressor requirements using the cumulative vasopressor index (CVI). Through a postmortem brain autopsy in non-survivors, the severity of the HIE was histopathologically dichotomized into no/mild and severe HIE. In survivors, we dichotomized the severity of HIE into no/mild cerebral performance category (CPC) 1 and severe HIE (CPC 4). We investigated the regain of consciousness, causes of death, and 5-day survival as hemodynamic confounders.

Results

Among the 350 non-survivors, 117 had histopathologically severe HIE while 233 had no/mild HIE, without differences observed in the MAP (73.1 vs. 72.0 mmHg, pgroup = 0.639). Compared to the non-survivors, 211 patients with CPC 1 and 57 patients with CPC 4 had higher MAP values that showed significant, but clinically non-relevant, MAP differences (81.2 vs. 82.3 mmHg, pgroup < 0.001). The no/mild HIE non-survivors (n = 54), who regained consciousness before death, had higher MAP values compared to those with no/mild HIE (n = 179), who remained persistently comatose (74.7 vs. 69.3 mmHg, pgroup < 0.001). The no/mild HIE non-survivors, who regained consciousness, required fewer vasopressors (CVI 2.1 vs. 3.6, pgroup < 0.001). Independent of the severity of HIE, the survivors were weaned faster from vasopressors (CVI 1.0).

Conclusions

Although a higher MAP was associated with survival in CA patients treated with a vasopressor-supported MAP target above 65 mmHg, the severity of HIE was not. Awakening from coma was associated with less vasopressor requirements. Our results provide no evidence for a MAP target above the current guideline recommendations that can decrease the severity of HIE.

Lower versus higher blood pressure targets in comatose patients resuscitated from out-of-hospital cardiac arrest-Protocol for a secondary Bayesian analysis of the box trial

BACKGROUND

The management of blood pressure targets during intensive care after out-of-hospital cardiac arrest (OHCA) remains a topic of debate. The blood Pressure and Oxygenation Targets After OHCA (BOX) trial explored the efficacy of two different blood pressure targets in 789 patients during intensive care after OHCA. In the primary frequentist analysis, no statistically significant differences were found for neurological outcome after 90 days.

METHODS

This protocol outlines secondary Bayesian analyses of 365-day all-cause mortality and two secondary outcomes: neurological outcome after 365 days, and plasma neuron-specific enolase, a biomarker of brain injury, after 48 h. We will employ adjusted Bayesian logistic and linear regressions, presenting results as relative and absolute differences with 95% confidence intervals. We will use weakly informative priors for the primary analyses, and skeptical and evidence-based priors (where available) in sensitivity analyses. Exact probabilities for any benefit/harm will be presented for all outcomes, along with probabilities of clinically important benefit/harm (risk differences larger than 2%-points absolute) and no clinically important differences for the binary outcomes. We will assess whether heterogeneity of treatment effects on mortality is present according to lactate at admission, time to return of spontaneous circulation, primary shockable rhythm, age, hypertension, and presence of ST-elevation myocardial infarction.

DISCUSSION

This secondary analysis of the BOX trial aim to complement the primary frequentist analysis by quantifying the probabilities of beneficial or harmful effects of different blood pressure targets. This approach seeks to provide clearer insights for researchers and clinicians into the effectiveness of these blood pressure management strategies in acute medical conditions, particularly focusing on mortality, neurological outcomes, and neuron-specific enolase.

Low Versus High Blood Pressure Targets in Critically Ill and Surgical Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

Hypotension is associated with adverse outcomes in critically ill and perioperative patients. However, these assumptions are supported by observational studies. This meta-analysis of randomized controlled trials aims to compare the impact of lower versus higher blood pressure targets on mortality.

DATA SOURCES

We searched PubMed, Cochrane, and Scholar from inception to February 10, 2024.

STUDY SELECTION

Randomized trials comparing lower versus higher blood pressure targets in the management of critically ill and perioperative settings.

DATA EXTRACTION

The primary outcome was all-cause mortality at the longest follow-up available. This review was registered in the Prospective International Register of Systematic Reviews, CRD42023452928.

DATA SYNTHESIS

Of 2940 studies identified by the search string, 28 (12 in critically ill and 16 in perioperative settings) were included totaling 15,672 patients. Patients in the low blood pressure target group had lower mortality (23 studies included: 1019/7679 [13.3%] vs. 1103/7649 [14.4%]; relative risk 0.93; 95% CI, 0.87-0.99; p = 0.03; I2 = 0%). This corresponded to a 97.4% probability of any increase in mortality with a Bayesian approach. These findings were mainly driven by studies performed in the ICU setting and with treatment lasting more than 24 hours; however, the magnitude and direction of the results were similar in the majority of sensitivity analyses including the analysis restricted to low risk of bias studies. We also observed a lower rate of atrial fibrillation and fewer patients requiring transfusion in low-pressure target groups. No differences were found in the other secondary outcomes.

CONCLUSIONS

Based on pooled randomized trial evidence, a lower compared with a higher blood pressure target results in a reduction of mortality, atrial fibrillation, and transfusion requirements. Lower blood pressure targets may be beneficial but there is ongoing uncertainty. However, the present meta-analysis does not confirm previous findings and recommendations. These results might inform future guidelines and promote the study of the concept of protective hemodynamics.

Canadian Cardiovascular Society/Canadian Cardiovascular Critical Care Society/Canadian Association of Interventional Cardiology Clinical Practice Update on Optimal Post Cardiac Arrest and Refractory Cardiac Arrest Patient Care

Survival to hospital discharge among patients with out-of-hospital cardiac arrest (OHCA) is low and important regional differences in treatment practices and survival have been described. Since the 2017 publication of the Canadian Cardiovascular Society's position statement on OHCA care, multiple randomized controlled trials have helped to better define optimal post cardiac arrest care. This working group provides updated guidance on the timing of cardiac catheterization in patients with ST-elevation and without ST-segment elevation, on a revised temperature control strategy targeting normothermia instead of hypothermia, blood pressure, oxygenation, and ventilation parameters, and on the treatment of rhythmic and periodic electroencephalography patterns in patients with a resuscitated OHCA. In addition, prehospital trials have helped craft new expert opinions on antiarrhythmic strategies (amiodarone or lidocaine) and outline the potential role for double sequential defibrillation in patients with refractory cardiac arrest when equipment and training is available. Finally, we advocate for regionalized OHCA care systems with admissions to a hospital capable of integrating their post OHCA care with comprehensive on-site cardiovascular services and provide guidance on the potential role of extracorporeal cardiopulmonary resuscitation in patients with refractory cardiac arrest. We believe that knowledge translation through national harmonization and adoption of contemporary best practices has the potential to improve survival and functional outcomes in the OHCA population.

Association among blood pressure, end-tidal carbon dioxide, peripheral oxygen saturation and mortality in prehospital post-resuscitation care

Aim

Post-resuscitation care is described as the fourth link in a chain of survival in resuscitation guidelines. However, data on prehospital post-resuscitation care is scarce. We aimed to examine the association among systolic blood pressure (SBP), peripheral oxygen saturation (SpO2) and end-tidal carbon dioxide (EtCO2) after prehospital stabilisation and outcome among patients resuscitated from out-of-hospital cardiac arrest (OHCA).

Methods

In this retrospective study, we evaluated association of the last measured prehospital SBP, SpO2 and EtCO2 before patient handover with 30-day and one-year mortality in 2,611 patients receiving prehospital post-resuscitation care by helicopter emergency medical services in Finland. Statistical analyses were completed through locally estimated scatterplot smoothing (LOESS) and multivariable logistic regression. The regression analyses were adjusted by sex, age, initial rhythm, bystander CPR, and time interval from collapse to the return of spontaneous circulation (ROSC).

Results

Mortality related to SBP and EtCO2 values were U-shaped and lowest at 135 mmHg and 4.7 kPa, respectively, whereas higher SpO2 shifted towards lower mortality. In adjusted analyses, increased 30-day mortality and one year mortality was observed in patients with SBP < 100 mmHg (OR 1.9 [95% CI 1.4-2.4]) and SBP < 100 (OR 1.8 [1.2-2.6]) or EtCO2 < 4.0 kPa (OR 1.4 [1.1-1.5]), respectively. SpO2 was not significantly associated with either 30-day or one year mortality.

Conclusions

After prehospital post-resuscitation stabilization, SBP < 100 mmHg and EtCO2 < 4.0 kPa were observed to be independently associated with higher mortality. The optimal targets for prehospital post-resuscitation care need to be established in the prospective studies.

Wolf Creek XVII Part 8: Neuroprotection

Introduction

Post-cardiac arrest brain injury (PCABI) is the primary determinant of clinical outcomes for patients who achieve return of spontaneous circulation after cardiac arrest (CA). There are limited neuroprotective therapies available to mitigate the acute pathophysiology of PCABI.

Methods

Neuroprotection was one of six focus topics for the Wolf Creek XVII Conference held on June 14-17, 2023 in Ann Arbor, Michigan, USA. Conference invitees included international thought leaders and scientists in the field of CA resuscitation from academia and industry. Participants submitted via online survey knowledge gaps, barriers to translation, and research priorities for each focus topic. Expert panels used the survey results and their own perspectives and insights to create and present a preliminary unranked list for each category that was debated, revised and ranked by all attendees to identify the top 5 for each category.

Results

Top 5 knowledge gaps included developing therapies for neuroprotection; improving understanding of the pathophysiology, mechanisms, and natural history of PCABI; deploying precision medicine approaches; optimizing resuscitation and CPR quality; and determining optimal timing for and duration of interventions. Top 5 barriers to translation included patient heterogeneity; nihilism & lack of knowledge about cardiac arrest; challenges with the translational pipeline; absence of mechanistic biomarkers; and inaccurate neuro-triage and neuroprognostication. Top 5 research priorities focused on translational research and trial optimization; addressing patient heterogeneity and individualized interventions; improving understanding of pathophysiology and mechanisms; developing mechanistic and outcome biomarkers across post-CA time course; and improving implementation of science and technology.

Conclusion

This overview can serve as a guide to transform the care and outcome of patients with PCABI. Addressing these topics has the potential to improve both research and clinical care in the field of neuroprotection for PCABI.

Critical Care Management of Patients After Cardiac Arrest: A Scientific Statement from the American Heart Association and Neurocritical Care Society

The critical care management of patients after cardiac arrest is burdened by a lack of high-quality clinical studies and the resultant lack of high-certainty evidence. This results in limited practice guideline recommendations, which may lead to uncertainty and variability in management. Critical care management is crucial in patients after cardiac arrest and affects outcome. Although guidelines address some relevant topics (including temperature control and neurological prognostication of comatose survivors, 2 topics for which there are more robust clinical studies), many important subject areas have limited or nonexistent clinical studies, leading to the absence of guidelines or low-certainty evidence. The American Heart Association Emergency Cardiovascular Care Committee and the Neurocritical Care Society collaborated to address this gap by organizing an expert consensus panel and conference. Twenty-four experienced practitioners (including physicians, nurses, pharmacists, and a respiratory therapist) from multiple medical specialties, levels, institutions, and countries made up the panel. Topics were identified and prioritized by the panel and arranged by organ system to facilitate discussion, debate, and consensus building. Statements related to postarrest management were generated, and 80% agreement was required to approve a statement. Voting was anonymous and web based. Topics addressed include neurological, cardiac, pulmonary, hematological, infectious, gastrointestinal, endocrine, and general critical care management. Areas of uncertainty, areas for which no consensus was reached, and future research directions are also included. Until high-quality studies that inform practice guidelines in these areas are available, the expert panel consensus statements that are provided can advise clinicians on the critical care management of patients after cardiac arrest.

Recovery and Survival of Patients After Out-of-Hospital Cardiac Arrest: A Literature Review Showcasing the Big Picture of Intensive Care Unit-Related Factors

As an important public health issue, out-of-hospital cardiac arrest (OHCA) requires several stages of high quality medical care, both on-field and after hospital admission. Post-cardiac arrest shock can lead to severe neurological injury, resulting in poor recovery outcome and increased risk of death. These characteristics make this condition one of the most important issues to deal with in post-OHCA patients hospitalized in intensive care units (ICUs). Also, the majority of initial post-resuscitation survivors have underlying coronary diseases making revascularization procedure another crucial step in early management of these patients. Besides keeping myocardial blood flow at a satisfactory level, other tissues must not be neglected as well, and maintaining mean arterial pressure within optimal range is also preferable. All these procedures can be simplified to a certain level along with using targeted temperature management methods in order to decrease metabolic demands in ICU-hospitalized post-OHCA patients. Additionally, withdrawal of life-sustaining therapy as a controversial ethical topic is under constant re-evaluation due to its possible influence on overall mortality rates in patients initially surviving OHCA. Focusing on all of these important points in process of managing ICU patients is an imperative towards better survival and complete recovery rates.

Neuromonitoring after Pediatric Cardiac Arrest: Cerebral Physiology and Injury Stratification

BACKGROUND

Significant long-term neurologic disability occurs in survivors of pediatric cardiac arrest, primarily due to hypoxic-ischemic brain injury. Postresuscitation care focuses on preventing secondary injury and the pathophysiologic cascade that leads to neuronal cell death. These injury processes include reperfusion injury, perturbations in cerebral blood flow, disturbed oxygen metabolism, impaired autoregulation, cerebral edema, and hyperthermia. Postresuscitation care also focuses on early injury stratification to allow clinicians to identify patients who could benefit from neuroprotective interventions in clinical trials and enable targeted therapeutics.

METHODS

In this review, we provide an overview of postcardiac arrest pathophysiology, explore the role of neuromonitoring in understanding postcardiac arrest cerebral physiology, and summarize the evidence supporting the use of neuromonitoring devices to guide pediatric postcardiac arrest care. We provide an in-depth review of the neuromonitoring modalities that measure cerebral perfusion, oxygenation, and function, as well as neuroimaging, serum biomarkers, and the implications of targeted temperature management.

RESULTS

For each modality, we provide an in-depth review of its impact on treatment, its ability to stratify hypoxic-ischemic brain injury severity, and its role in neuroprognostication.

CONCLUSION

Potential therapeutic targets and future directions are discussed, with the hope that multimodality monitoring can shift postarrest care from a one-size-fits-all model to an individualized model that uses cerebrovascular physiology to reduce secondary brain injury, increase accuracy of neuroprognostication, and improve outcomes.

Critical Care Management of Patients After Cardiac Arrest: A Scientific Statement From the American Heart Association and Neurocritical Care Society

The critical care management of patients after cardiac arrest is burdened by a lack of high-quality clinical studies and the resultant lack of high-certainty evidence. This results in limited practice guideline recommendations, which may lead to uncertainty and variability in management. Critical care management is crucial in patients after cardiac arrest and affects outcome. Although guidelines address some relevant topics (including temperature control and neurological prognostication of comatose survivors, 2 topics for which there are more robust clinical studies), many important subject areas have limited or nonexistent clinical studies, leading to the absence of guidelines or low-certainty evidence. The American Heart Association Emergency Cardiovascular Care Committee and the Neurocritical Care Society collaborated to address this gap by organizing an expert consensus panel and conference. Twenty-four experienced practitioners (including physicians, nurses, pharmacists, and a respiratory therapist) from multiple medical specialties, levels, institutions, and countries made up the panel. Topics were identified and prioritized by the panel and arranged by organ system to facilitate discussion, debate, and consensus building. Statements related to postarrest management were generated, and 80% agreement was required to approve a statement. Voting was anonymous and web based. Topics addressed include neurological, cardiac, pulmonary, hematological, infectious, gastrointestinal, endocrine, and general critical care management. Areas of uncertainty, areas for which no consensus was reached, and future research directions are also included. Until high-quality studies that inform practice guidelines in these areas are available, the expert panel consensus statements that are provided can advise clinicians on the critical care management of patients after cardiac arrest.

Association of blood pressure with neurologic outcome at hospital discharge after pediatric cardiac arrest resuscitation

BACKGROUND

Poor outcomes are associated with post cardiac arrest blood pressures <5th percentile for age. We aimed to study the relationship of mean arterial pressure (MAP) with favorable neurologic outcome following cardiac arrest and return of spontaneous circulation (ROSC).

METHODS

This retrospective, multi-center, observational study analyzed data from the Pediatric Resuscitation Quality Collaborative (pediRES-Q). Children (<18 years) who achieved ROSC following index in-hospital or out-of-hospital cardiac arrest and survived ≥6 hours were included. Lowest documented MAP within the first 6 hours of ROSC was percentile adjusted for age and categorized into six groups - Group I: <5th, II: 5-24th, III: 25-49th, IV: 50-74th, V: 75-94th; and VI: 95-100th percentile. Primary outcome was favorable neurologic status at hospital discharge, defined as PCPC score 1, 2, or no change from pre-arrest baseline. Multivariable logistic regression was performed to analyze the association of MAP group with favorable outcome, controlling for illness category (surgical-cardiac), initial rhythm (shockable), arrest time (weekend or overnight), age, CPR duration, and clustering by site.

RESULTS

787 patients were included: median [Q1,Q3] age 17.9 [4.8,90.6] months; male 58%; OHCA 21%; shockable rhythm 13%; CPR duration 7 [3,16] min; favorable neurologic outcome 54%. Median lowest documented MAP percentile for the favorable outcome group was 13 [3,43] versus 8 [1,37] for the unfavorable group. The distribution of blood pressures by MAP group was I: 37%, II: 28%, III: 13%, IV: 11%, V: 7%, and VI: 4%. Compared with patients in Group I (<5%ile), Groups II, III, and IV had higher odds of favorable outcome (aOR, 1.84 [95% CI, 1.24, 2.73]; 2.20 [95% CI, 1.32, 3.68]; 1.90 [95% CI, 1.12, 3.25]). There was no association between Groups V or VI and favorable outcome (aOR, 1.44 [95% CI, 0.75, 2.80]; 1.11 [95% CI, 0.47, 2.59]).

CONCLUSION

In the first 6-hours post-ROSC, a lowest documented MAP between the 5th-74th percentile for age was associated with favorable neurologic outcome compared to MAP <5th percentile for age.

Nurse management of noradrenaline infusions in intensive care units: An observational study

BACKGROUND

Intensive care nurse management of noradrenaline (norepinephrine) infusions is a common and essential clinical competency for patient haemodynamic support. Nurses titrate and wean noradrenaline infusions to a target blood pressure in a dynamic, high-risk, and unpredictable environment. Titration and weaning are complex interventions, and blood pressure goals are often variable.

OBJECTIVES

The aim was to examine how nurses used blood pressure targets when escalating, weaning, and titrating noradrenaline in intensive care patients admitted for haemodynamic management and explore patient blood pressure responses to changes in noradrenaline doses.

METHODS

In this naturalistic observational study, noradrenaline dose changes were classified as escalation, weaning, and titration changes and analysed to explore nursing practice. The study was undertaken in two adult medical/surgical intensive care units in Melbourne, Australia. Participants included intensive care nurses and patients who received noradrenaline infusions for haemodynamic support.

RESULTS

Observations of 14 nurse-patient dyads provided 25 h of blood pressure and noradrenaline dose data. Patient participants received weight-adjusted maximum noradrenaline doses of between 0.06 mcg/kg/min and 0.87 mcg/kg/minute, with those in the escalation group receiving dose increases of up to 5 mcg to achieve blood pressure goals. During weaning, patients maintained or increased their blood pressure as noradrenaline doses were decreased. Nurses consistently maintained blood pressures at higher than target goals, and despite constant fluctuations, they only documented blood pressure readings hourly.

CONCLUSIONS

Intensive care nurses managed noradrenaline to achieve mean arterial pressure targets that were variable and not evidence based. The disconnection between observed blood pressure fluctuations and nurse documentation of patient blood pressures was reflected in titration practices. Discrepancies between documented and actual blood pressures raised issues about data used by nurses and doctors to inform clinical practice on noradrenaline management.

Impact of blood pressure targets on central hemodynamics during intensive care after out-of-hospital cardiac arrest

OBJECTIVES

The aim was to investigate the advanced hemodynamic effects of the two MAP-targets during intensive care on systemic hemodynamics in comatose patients after cardiac arrest.

DESIGN

Secondary analysis of a randomized controlled trial.

SETTING

Primary vasopressor used was per protocol norepinephrine. Hemodynamic monitoring was done with pulmonary artery catheters (PAC) and measurements were made on predefined time points. The primary endpoint of this substudy was the difference in cardiac index within 48 h from a repeated measurements-mixed model. Secondary endpoints included systemic vascular resistance index (SVRI), heart rate, and stroke volume index.

PATIENTS

Comatose survivors after out-of-hospital cardiac arrest.

INTERVENTIONS

The "Blood pressure and oxygenations targets after out-of-hospital cardiac arrest (BOX)"-trial was a randomized, controlled, double-blinded, multicenter-study comparing targeted mean arterial pressure (MAP) of 63 mmHg (MAP63) vs 77 mmHg (MAP77).

MEASUREMENTS AND MAIN RESULTS

Among 789 randomized patients, 730 (93%) patients were included in the hemodynamic substudy. From PAC-insertion (median 1 hours after ICU-admission) and the next 48 hours, the MAP77-group received significantly higher doses of norepinephrine (mean difference 0.09 µg/kg/min, 95% confidence interval (CI) 0.07-0.11, pgroup < 0.0001). Cardiac index was significantly increased (0.20 L/min/m2 (CI 0.12-0.28), pgroup < 0.0001) as was SVRI with an overall difference of (43 dynes m2/s/cm5 (CI 7-79); pgroup = 0.02). Heart rate was increased in the MAP77-group (4 beats/minute; CI 2-6, pgroup < 0.003), but stroke volume index was not (pgroup = 0.10).

CONCLUSIONS

Targeted MAP at 77 mmHg compared to 63 mmHg resulted in a higher dose of norepinephrine, increased cardiac index and SVRI. Heart rate was also increased, but stroke volume index was not affected by a higher blood pressure target.

High versus low mean arterial pressure targets after out-of-hospital cardiac arrest: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Targeting a specific mean arterial pressure (MAP) has been evaluated as a treatment strategy after out-of-hospital cardiac arrest (OHCA) resuscitation. However, the current evidence lacks clear guidelines regarding the optimal MAP target after OHCA.

METHODS

A systematic review and meta-analysis synthesizing randomized controlled trials (RCTs), retrieved by systematically searching: PubMed, EMBASE, WOS, SCOPUS, and Cochrane through January 18th, 2023. Our review protocol was prospectively published on PROSPERO with ID: CRD42023395333.

RESULTS

Four RCTs with a total of 1065 patients were included in our analysis. There was no difference between high MAP versus low MAP regarding the primary outcomes: all-cause mortality (RR: 1.07 with a 95% CI [0.91, 1.27], P = 0.4) and favorable neurological recovery (RR: 1.02 with a 95% CI [0.93, 1.13], P = 0.68). However, high MAP target was significantly associated with decreased ICU stay duration (MD: -0.78 with a 95 CI [-1.54, -0.02], P = 0.04) and mechanical ventilation duration (MD: -0.91 with a 95 CI of [-1.51, -0.31], P = 0.003).

CONCLUSION

A high MAP target may reduce ICU stay and mechanical ventilation duration but did not demonstrate improvements in either mortality or favorable neurological recovery. Therefore, the role of high MAP target remains uncertain and requires further RCTs.

Postresuscitation management

PURPOSE OF REVIEW

To describe the most recent scientific evidence on ventilation/oxygenation, circulation, temperature control, general intensive care, and prognostication after successful resuscitation from adult cardiac arrest.

RECENT FINDINGS

Targeting a lower oxygen target (90-94%) is associated with adverse outcome. Targeting mild hypercapnia is not associated with improved functional outcomes or survival. There is no compelling evidence supporting improved outcomes associated with a higher mean arterial pressure target compared to a target of >65 mmHg. Noradrenalin seems to be the preferred vasopressor. A low cardiac index is common over the first 24 h but aggressive fluid loading and the use of inotropes are not associated with improved outcome. Several meta-analyses of randomized clinical trials show conflicting results whether hypothermia in the 32-34°C range as compared to normothermia or no temperature control improves functional outcome. The role of sedation is currently under evaluation. Observational studies suggest that the use of neuromuscular blockade may be associated with improved survival and functional outcome. Prophylactic antibiotic does not impact on outcome. No single predictor is entirely accurate to determine neurological prognosis. The presence of at least two predictors of severe neurological injury indicates that an unfavorable neurological outcome is very likely.

SUMMARY

Postresuscitation care aims for normoxemia, normocapnia, and normotension. The optimal target core temperature remains a matter of debate, whether to implement temperature management within the 32-34°C range or focus on fever prevention, as recommended in the latest European Resuscitation Council/European Society of Intensive Care Medicine guidelines Prognostication of neurological outcome demands a multimodal approach.

The effect of higher or lower mean arterial pressure on kidney function after cardiac arrest: a post hoc analysis of the COMACARE and NEUROPROTECT trials

BACKGROUND

We aimed to study the incidence of acute kidney injury (AKI) in out-of-hospital cardiac arrest (OHCA) patients treated according to low-normal or high-normal mean arterial pressure (MAP) targets.

METHODS

A post hoc analysis of the COMACARE (NCT02698917) and Neuroprotect (NCT02541591) trials that randomized patients to lower or higher targets for the first 36 h of intensive care. Kidney function was defined using the Kidney Disease Improving Global Outcome (KDIGO) classification. We used Cox regression analysis to identify factors associated with AKI after OHCA.

RESULTS

A total of 227 patients were included: 115 in the high-normal MAP group and 112 in the low-normal MAP group. Eighty-six (38%) patients developed AKI during the first five days; 40 in the high-normal MAP group and 46 in the low-normal MAP group (p = 0.51). The median creatinine and daily urine output were 85 μmol/l and 1730 mL/day in the high-normal MAP group and 87 μmol/l and 1560 mL/day in the low-normal MAP group. In a Cox regression model, independent AKI predictors were no bystander cardiopulmonary resuscitation (p < 0.01), non-shockable rhythm (p < 0.01), chronic hypertension (p = 0.03), and time to the return of spontaneous circulation (p < 0.01), whereas MAP target was not an independent predictor (p = 0.29).

CONCLUSION

Any AKI occurred in four out of ten OHCA patients. We found no difference in the incidence of AKI between the patients treated with lower and those treated with higher MAP after CA. Higher age, non-shockable initial rhythm, and longer time to ROSC were associated with shorter time to AKI.

CLINICAL TRIAL REGISTRATION

COMACARE (NCT02698917), NEUROPROTECT (NCT02541591).

Cerebral hemodynamics after cardiac arrest: implications for clinical management

Following resuscitation from cardiac arrest, hypoxic ischemic brain injury (HIBI) ensues, which is the primary determinant of adverse outcome. The pathophysiology of HIBI can be compartmentalized into primary and secondary injury, resulting from cerebral ischemia during cardiac arrest and reperfusion following successful resuscitation, respectively. During the secondary injury phase, increased attention has been directed towards the optimization of cerebral oxygen delivery to prevent additive injury to the brain. During this phase, cerebral hemodynamics are characterized by early hyperemia following resuscitation and then a protracted phase of cerebral hypoperfusion termed "no-reflow" during which additional hypoxic-ischemic injury can occur. As such, identification of therapeutic strategies to optimize cerebral delivery of oxygen is at the forefront of HIBI research. Unfortunately, randomized control trials investigating the manipulation of arterial carbon dioxide tension and mean arterial pressure augmentation as methods to potentially improve cerebral oxygen delivery have shown no impact on clinical outcomes. Emerging literature suggests differential patient-specific phenotypes may exist in patients with HIBI. The potential to personalize therapeutic strategies in the critical care setting based upon patient-specific pathophysiology presents an attractive strategy to improve HIBI outcomes. Herein, we review the cerebral hemodynamic pathophysiology of HIBI, discuss patient phenotypes as it pertains to personalizing care, as well as suggest future directions.

Clinical targeting of the cerebral oxygen cascade to improve brain oxygenation in patients with hypoxic-ischaemic brain injury after cardiac arrest

The cerebral oxygen cascade includes three key stages: (a) convective oxygen delivery representing the bulk flow of oxygen to the cerebral vascular bed; (b) diffusion of oxygen from the blood into brain tissue; and (c) cellular utilisation of oxygen for aerobic metabolism. All three stages may become dysfunctional after resuscitation from cardiac arrest and contribute to hypoxic-ischaemic brain injury (HIBI). Improving convective cerebral oxygen delivery by optimising cerebral blood flow has been widely investigated as a strategy to mitigate HIBI. However, clinical trials aimed at optimising convective oxygen delivery have yielded neutral results. Advances in the understanding of HIBI pathophysiology suggest that impairments in the stages of the oxygen cascade pertaining to oxygen diffusion and cellular utilisation of oxygen should also be considered in identifying therapeutic strategies for the clinical management of HIBI patients. Culprit mechanisms for these impairments may include a widening of the diffusion barrier due to peri-vascular oedema and mitochondrial dysfunction. An integrated approach encompassing both intra-parenchymal and non-invasive neuromonitoring techniques may aid in detecting pathophysiologic changes in the oxygen cascade and enable patient-specific management aimed at reducing the severity of HIBI.

Neuroinflammation and the immune system in hypoxic ischaemic brain injury pathophysiology after cardiac arrest

Hypoxic ischaemic brain injury after resuscitation from cardiac arrest is associated with dismal clinical outcomes. To date, most clinical interventions have been geared towards the restoration of cerebral oxygen delivery after resuscitation; however, outcomes in clinical trials are disappointing. Therefore, alternative disease mechanism(s) are likely to be at play, of which the response of the innate immune system to sterile injured tissue in vivo after reperfusion has garnered significant interest. The innate immune system is composed of three pillars: (i) cytokines and signalling molecules; (ii) leucocyte migration and activation; and (iii) the complement cascade. In animal models of hypoxic ischaemic brain injury, pro-inflammatory cytokines are central to propagation of the response of the innate immune system to cerebral ischaemia-reperfusion. In particular, interleukin-1 beta and downstream signalling can result in direct neural injury that culminates in cell death, termed pyroptosis. Leucocyte chemotaxis and activation are central to the in vivo response to cerebral ischaemia-reperfusion. Both parenchymal microglial activation and possible infiltration of peripherally circulating monocytes might account for exacerbation of an immunopathological response in humans. Finally, activation of the complement cascade intersects with multiple aspects of the innate immune response by facilitating leucocyte activation, further cytokine release and endothelial activation. To date, large studies of immunomodulatory therapies have not been conducted; however, lessons learned from historical studies using therapeutic hypothermia in humans suggest that quelling an immunopathological response might be efficacious. Future work should delineate the precise pathways involved in vivo in humans to target specific signalling molecules.

State of the art post-cardiac arrest care: evolution and future of post cardiac arrest care

Out-of-hospital cardiac arrest is a leading cause of mortality. In the pre-hospital setting, bystander response with cardiopulmonary resuscitation and the use of publicly available automated external defibrillators have been associated with improved survival. Early in-hospital treatment still focuses on emergency coronary angiography for selected patients. For patients remaining comatose, temperature control to avoid fever is still recommended, but former hypothermic targets have been abandoned. For patients without spontaneous awakening, the use of a multimodal prognostication model is key. After discharge, follow-up with screening for cognitive and emotional disabilities is recommended. There has been an incredible evolution of research on cardiac arrest. Two decades ago, the largest trials include a few hundred patients. Today, undergoing studies are planning to include 10-20 times as many patients, with improved methodology. This article describes the evolution and perspectives for the future in post-cardiac arrest care.

Blood pressure targets and management during post-cardiac arrest care

Blood pressure is one modifiable physiological target in patients treated in the intensive care unit after cardiac arrest. Current Guidelines recommend targeting a mean arterial pressure (MAP) of higher than 65-70 mmHg using fluid resuscitation and the use of vasopressors. Management strategies will vary based in the setting, i.e. the pre-hospital compared to the in-hospital phase. Epidemiological data suggest that some degree of hypotension requiring vasopressors occur in almost 50% of patients. A higher MAP could theoretically increase coronary blood flow but on the other hand the use of vasopressor may result in an increase in cardiac oxygen demand and arrhythmia. An adequate MAP is paramount for maintaining cerebral blood flow. In some cardiac arrest patients the cerebral autoregulation may be disturbed resulting in the need for higher MAP in order to avoid decreasing cerebral blood flow. Thus far, four studies including little more than 1000 patients have compared a lower and higher MAP target in cardiac arrest patients. The achieved mean difference of MAP between groups has varied from 10-15 mmHg. Based on these studies a Bayesian meta-analysis suggests that the posterior probability that a future study would find treatment effects higher than a 5% difference between groups to be less than 50%. On the other hand, this analysis also suggests, that the likelihood of harm with a higher MAP target is also low. Noteworthy is that all studies to date have focused mainly on patients with a cardiac cause of the arrest with the majority of patients being resuscitated from a shockable initial rhythm. Future studies should aim to include also non-cardiac causes and aim to target a wider separation in MAP between groups.

Deep learning for EEG-based prognostication after cardiac arrest: from current research to future clinical applications

Outcome prognostication in comatose patients after cardiac arrest (CA) remains to date a challenge. The major determinant of clinical outcome is the post-hypoxic/ischemic encephalopathy. Electroencephalography (EEG) is routinely used to assess neural functions in comatose patients. Currently, EEG-based outcome prognosis relies on visual evaluation by medical experts, which is time consuming, prone to subjectivity, and oblivious to complex patterns. The field of deep learning has given rise to powerful algorithms for detecting patterns in large amounts of data. Analyzing EEG signals of coma patients with deep neural networks with the goal of assisting in outcome prognosis is therefore a natural application of these algorithms. Here, we provide the first narrative literature review on the use of deep learning for prognostication after CA. Existing studies show overall high performance in predicting outcome, relying either on spontaneous or on auditory evoked EEG signals. Moreover, the literature is concerned with algorithmic interpretability, and has shown that largely, deep neural networks base their decisions on clinically or neurophysiologically meaningful features. We conclude this review by discussing considerations that the fields of artificial intelligence and neurology will need to jointly address in the future, in order for deep learning algorithms to break the publication barrier, and to be integrated in clinical practice.

Blood Pressure Targets for Out-of-Hospital Cardiac Arrest: A Systematic Review and Meta-Analysis

BACKGROUND

With ideal mean arterial pressure (MAP) targets in resuscitated out-of-hospital cardiac arrest (OHCA) patients unknown, we performed a meta-analysis of randomised controlled trials (RCTs) to compare the effects of higher versus lower MAP targets.

METHODS

We searched four databases until 1 May 2023 for RCTs reporting the effects of higher MAP targets (>70 mmHg) in resuscitated OHCA patients and conducted random-effects meta-analyses. The primary outcome was mortality while secondary outcomes were neurological evaluations, arrhythmias, acute kidney injury, and durations of mechanical ventilation and ICU stay. We conducted inverse-variance weighted strata-level meta-regression against a proportion of non-survivors to assess differences between reported MAPs. We also conducted a trial sequential analysis of RCTs.

RESULTS

Four RCTs were included. Higher MAP was not associated with reduced mortality (OR: 1.09, 95%-CI: 0.84 to 1.42, p = 0.51), or improved neurological outcomes (OR: 0.99, 95%-CI: 0.77 to 1.27, p = 0.92). Such findings were consistent despite additional sensitivity analyses. Our robust variance strata-level meta-regression revealed no significant associations between mean MAP and the proportion of non-survivors (B: 0.029, 95%-CI: -0.023 to 0.081, p = 0.162), and trial sequential analysis revealed no meaningful survival benefit for higher MAPs.

CONCLUSIONS

A higher MAP target was not significantly associated with improved mortality and neurological outcomes in resuscitated OHCA patients.

Higher versus lower blood pressure targets after cardiac arrest: A meta-analysis of randomized controlled trials

A few mostly underpowered randomized controlled trials (RCTs) have been used to study the impact of blood pressure (BP) targets in out-of-hospital cardiac arrest (OHCA) patients. We aimed to perform an updated meta-analysis to compare the outcomes between the higher BP target and the lower BP target groups following OHCA. A systematic search was conducted on PubMed, Embase and the Cochrane Library until December 2022. We pooled odds ratios (ORs) and mean differences (MDs) with 95% confidence intervals (CIs) using RevMan 5.4. Our search yielded four RCTs with a total of 1114 patients. Regarding our primary outcome of all-cause mortality, there was no significant difference between higher versus lower BP target goals in post-OHCA patients (OR 1.12, 95% CI: 0.86 to 1.45). Furthermore, there were no significant differences between the two groups in good neurological outcome, the incidence of arrhythmia, need for renal replacement therapy, and the levels of neuron-specific enolase at 48 h. The length of ICU stay of patients treated with the higher BP target was significantly lower but by a small margin. These findings do not support the use of a higher BP target but are subject to confirmation by large-scale RCTs investigating homogenous BP goals.

High-normal versus low-normal mean arterial pressure thresholds in critically ill patients: a systematic review and meta-analysis of randomized trials

PURPOSE

Targeted blood pressure thresholds remain unclear in critically ill patients. Two prior systematic reviews have not shown differences in mortality with a high mean arterial pressure (MAP) threshold, but there have been new studies published since. Thus, we conducted an updated systematic review and meta-analysis of randomized controlled trials (RCTs) that compared the effect of a high-normal vs low-normal MAP on mortality, favourable neurologic outcome, need for renal replacement therapy, and adverse vasopressor-induced events in critically ill patients.

SOURCE

We searched six databases from inception until 1 October 2022 for RCTs of critically ill patients targeted to either a high-normal vs a low-normal MAP threshold for at least 24 hr. We assessed study quality using the revised Cochrane risk-of-bias 2 tool and the risk ratio (RR) was used as the summary measure of association. We used the Grading of Recommendations Assessment, Development, and Evaluation framework to assess the certainty of evidence.

PRINCIPAL FINDINGS

We included eight RCTs with 4,561 patients. Four trials were conducted in patients following out-of-hospital cardiac arrest, two in patients with distributive shock requiring vasopressors, one in patients with septic shock, and one in patients with hepatorenal syndrome. The pooled RRs for mortality (eight RCTs; 4,439 patients) and favourable neurologic outcome (four RCTs; 1,065 patients) were 1.06 (95% confidence interval [CI], 0.99 to 1.14; moderate certainty) and 0.99 (95% CI, 0.90 to 1.08; moderate certainty), respectively. The RR for the need for renal replacement therapy (four RCTs; 4,071 patients) was 0.97 (95% CI, 0.87 to 1.08; moderate certainty). There was no statistical between-study heterogeneity across all outcomes.

CONCLUSION

This updated systematic review and meta-analysis of RCTs found no differences in mortality, favourable neurologic outcome, or the need for renal replacement therapy between critically ill patients assigned to a high-normal vs low-normal MAP target.

STUDY REGISTRATION

PROSPERO (CRD42022307601); registered 28 February 2022.

Post-Cardiac Arrest Syndrome

Post-cardiac arrest syndrome (PCAS) is a multicomponent entity affecting many who survive an initial period of resuscitation following cardiac arrest. This focussed review explores some of the strategies for mitigating the effects of PCAS following the return of spontaneous circulation. We consider the current evidence for controlled oxygenation, strategies for blood-pressure targets, the timing of coronary reperfusion, and the evidence for temperature control and treatment of seizures. Despite several large trials investigating specific strategies to improve outcomes after cardiac arrest, many questions remain unanswered. Results of some studies suggest that interventions may benefit specific subgroups of cardiac arrest patients, but the optimal timing and duration of many interventions remain unknown. The role of intracranial pressure monitoring has been the subject of only a few studies, and its benefits remain unclear. Research aimed at improving the management of PCAS is ongoing.

Factors associated with circulatory death after out-of-hospital cardiac arrest: a population-based cluster analysis

BACKGROUND

Out-of-hospital cardiac arrest (OHCA) is a common cause of death. Early circulatory failure is the most common reason for death within the first 48 h. This study in intensive care unit (ICU) patients with OHCA was designed to identify and characterize clusters based on clinical features and to determine the frequency of death from refractory postresuscitation shock (RPRS) in each cluster.

METHODS

We retrospectively identified adults admitted alive to ICUs after OHCA in 2011-2018 and recorded in a prospective registry for the Paris region (France). We identified patient clusters by performing an unsupervised hierarchical cluster analysis (without mode of death among the variables) based on Utstein clinical and laboratory variables. For each cluster, we estimated the hazard ratio (HRs) for RPRS.

RESULTS

Of the 4445 included patients, 1468 (33%) were discharged alive from the ICU and 2977 (67%) died in the ICU. We identified four clusters: initial shockable rhythm with short low-flow time (cluster 1), initial non-shockable rhythm with usual absence of ST-segment elevation (cluster 2), initial non-shockable rhythm with long no-flow time (cluster 3), and long low-flow time with high epinephrine dose (cluster 4). RPRS was significantly associated with this last cluster (HR, 5.51; 95% confidence interval 4.51-6.74).

CONCLUSIONS

We identified patient clusters based on Utstein criteria, and one cluster was strongly associated with RPRS. This result may help to make decisions about using specific treatments after OHCA.

Higher versus lower blood pressure targets after cardiac arrest: systematic review with individual patient data meta-analysis

PURPOSE

Guidelines recommend targeting mean arterial pressure (MAP) > 65 mmHg in patients after cardiac arrest (CA). Recent trials have studied the effects of targeting a higher MAP as compared to a lower MAP after CA. We performed a systematic review and individual patient data meta-analysis to investigate the effects of higher versus lower MAP targets on patient outcome.

METHOD

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, LILACS, BIOSIS, CINAHL, Scopus, the Web of Science Core Collection, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry, Google Scholar and the Turning Research into Practice database to identify trials randomizing patients to higher (≥ 71 mmHg) or lower (≤70 mmHg) MAP targets after CA and resuscitation. We used the Cochrane Risk of Bias tool, version 2 (RoB 2) to assess for risk of bias. The primary outcomes were 180-day all-cause mortality and poor neurologic recovery defined by a modified Rankin score of 4-6 or a cerebral performance category score of 3-5.

RESULTS

Four eligible clinical trials were identified, randomizing a total of 1,087 patients. All the included trials were assessed as having a low risk for bias. The risk ratio (RR) with 95% confidence interval for 180-day all-cause mortality for a higher versus a lower MAP target was 1.08 (0.92-1.26) and for poor neurologic recovery 1.01 (0.86-1.19). Trial sequential analysis showed that a 25% or higher treatment effect, i.e., RR<0.75, can be excluded. No difference in serious adverse events was found between the higher and lower MAP groups.

CONCLUSIONS

Targeting a higher MAP compared to a lower MAP is unlikely to reduce mortality or improve neurologic recovery after CA. Only a large treatment effect above 25% (RR<0.75) could be excluded, and future studies are needed to investigate if relevant but lower treatment effect exists. Targeting a higher MAP was not associated with any increase in adverse effects.

Association between the Cardiac Arrest Hospital Prognosis (CAHP) score and reason for death after successfully resuscitated cardiac arrest

Individualize treatment after cardiac arrest could potentiate future clinical trials selecting patients most likely to benefit from interventions. We assessed the Cardiac Arrest Hospital Prognosis (CAHP) score for predicting reason for death to improve patient selection. Consecutive patients in two cardiac arrest databases were studied between 2007 and 2017. Reasons for death were categorised as refractory post-resuscitation shock (RPRS), hypoxic-ischaemic brain injury (HIBI) and other. We computed the CAHP score, which relies on age, location at OHCA, initial cardiac rhythm, no-flow and low-flow times, arterial pH, and epinephrine dose. We performed survival analyses using the Kaplan-Meier failure function and competing-risks regression. Of 1543 included patients, 987 (64%) died in the ICU, 447 (45%) from HIBI, 291 (30%) from RPRS, and 247 (25%) from other reasons. The proportion of deaths from RPRS increased with CAHP score deciles; the sub-hazard ratio for the tenth decile was 30.8 (9.8-96.5; p < 0.0001). The sub-hazard ratio of the CAHP score for predicting death from HIBI was below 5. Higher CAHP score values were associated with a higher proportion of deaths due to RPRS. This score may help to constitute uniform patient populations likely to benefit from interventions assessed in future randomised controlled trials.

Neuroprognostication in the Post Cardiac Arrest Patient: A Canadian Cardiovascular Society Position Statement

Cardiac arrest (CA) is associated with a low rate of survival with favourable neurologic recovery. The most common mechanism of death after successful resuscitation from CA is withdrawal of life-sustaining measures on the basis of perceived poor neurologic prognosis due to underlying hypoxic-ischemic brain injury. Neuroprognostication is an important component of the care pathway for CA patients admitted to hospital but is complex, challenging, and often guided by limited evidence. Using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system to evaluate the evidence underlying factors or diagnostic modalities available to determine prognosis, recommendations were generated in the following domains: (1) circumstances immediately after CA; (2) focused neurologic exam; (3) myoclonus and seizures; (4) serum biomarkers; (5) neuroimaging; (6) neurophysiologic testing; and (7) multimodal neuroprognostication. This position statement aims to serve as a practical guide to enhance in-hospital care of CA patients and emphasizes the adoption of a systematic, multimodal approach to neuroprognostication. It also highlights evidence gaps.

Brain monitoring after cardiac arrest

PURPOSE OF REVIEW

To describe the available neuromonitoring tools in patients who are comatose after resuscitation from cardiac arrest because of hypoxic-ischemic brain injury (HIBI).

RECENT FINDINGS

Electroencephalogram (EEG) is useful for detecting seizures and guiding antiepileptic treatment. Moreover, specific EEG patterns accurately identify patients with irreversible HIBI. Cerebral blood flow (CBF) decreases in HIBI, and a greater decrease with no CBF recovery indicates poor outcome. The CBF autoregulation curve is narrowed and right-shifted in some HIBI patients, most of whom have poor outcome. Parameters derived from near-infrared spectroscopy (NIRS), intracranial pressure (ICP) and transcranial Doppler (TCD), together with brain tissue oxygenation, are under investigation as tools to optimize CBF in patients with HIBI and altered autoregulation. Blood levels of brain biomarkers and their trend over time are used to assess the severity of HIBI in both the research and clinical setting, and to predict the outcome of postcardiac arrest coma. Neuron-specific enolase (NSE) is recommended as a prognostic tool for HIBI in the current postresuscitation guidelines, but other potentially more accurate biomarkers, such as neurofilament light chain (NfL) are under investigation.

SUMMARY

Neuromonitoring provides essential information to detect complications, individualize treatment and predict prognosis in patients with HIBI.

One-Year Review in Cardiac Arrest: The 2022 Randomized Controlled Trials

Cardiac arrest, one of the leading causes of death, accounts for numerous clinical studies published each year. This review summarizes the findings of all the randomized controlled clinical trials (RCT) on cardiac arrest published in the year 2022. The RCTs are presented according to the following categories: out-of- and in-hospital cardiac arrest (OHCA, IHCA) and post-cardiac arrest care. Interestingly, more than 80% of the RCTs encompassed advanced life support and post-cardiac arrest care, while no studies focused on the treatment of IHCA, except for one that, however, explored the temperature control after resuscitation in this population. Surprisingly, 9 out of 11 RCTs led to neutral results demonstrating equivalency between the newly tested interventions compared to current practice. One trial was negative, showing that oxygen titration in the immediate pre-hospital post-resuscitation period decreased survival compared to a more liberal approach. One RCT was positive and introduced new defibrillation strategies for refractory cardiac arrest. Overall, data from the 2022 RCTs discussed here provide a solid basis to generate new hypotheses to be tested in future clinical studies.

A randomized, double-blind trial comparing the effect of two blood pressure targets on global brain metabolism after out-of-hospital cardiac arrest

PURPOSE

This study aimed to assess the effect of different blood pressure levels on global cerebral metabolism in comatose patients resuscitated from out-of-hospital cardiac arrest (OHCA).

METHODS

In a double-blinded trial, we randomly assigned 60 comatose patients following OHCA to low (63 mmHg) or high (77 mmHg) mean arterial blood pressure (MAP). The trial was a sub-study in the Blood Pressure and Oxygenation Targets after Out-of-Hospital Cardiac Arrest-trial (BOX). Global cerebral metabolism utilizing jugular bulb microdialysis (JBM) and cerebral oxygenation (rSO₂) was monitored continuously for 96 h. The lactate-to-pyruvate (LP) ratio is a marker of cellular redox status and increases during deficient oxygen delivery (ischemia, hypoxia) and mitochondrial dysfunction. The primary outcome was to compare time-averaged means of cerebral energy metabolites between MAP groups during post-resuscitation care. Secondary outcomes included metabolic patterns of cerebral ischemia, rSO₂, plasma neuron-specific enolase level at 48 h and neurological outcome at hospital discharge (cerebral performance category).

RESULTS

We found a clear separation in MAP between the groups (15 mmHg, p < 0.001). Cerebral biochemical variables were not significantly different between MAP groups (LPR low MAP 19 (16-31) vs. high MAP 23 (16-33), p = 0.64). However, the LP ratio remained high (> 16) in both groups during the first 30 h. During the first 24 h, cerebral lactate > 2.5 mM, pyruvate levels > 110 µM, LP ratio > 30, and glycerol > 260 µM were highly predictive for poor neurological outcome and death with AUC 0.80. The median (IQR) rSO₂ during the first 48 h was 69.5% (62.0-75.0%) in the low MAP group and 69.0% (61.3-75.5%) in the high MAP group, p = 0.16.

CONCLUSIONS

Among comatose patients resuscitated from OHCA, targeting a higher MAP 180 min after ROSC did not significantly improve cerebral energy metabolism within 96 h of post-resuscitation care. Patients with a poor clinical outcome exhibited significantly worse biochemical patterns, probably illustrating that insufficient tissue oxygenation and recirculation during the initial hours after ROSC were essential factors determining neurological outcome.

Regional Cerebral Oxygen Saturation to Predict Favorable Outcome in Extracorporeal Cardiopulmonary Resuscitation: A Systematic Review and Meta-Analysis

OBJECTIVE

This systematic review and meta-analysis aimed to investigate the role of regional cerebral oxygen saturation (rSO₂) in predicting survival and neurologic outcomes after extracorporeal cardiopulmonary resuscitation (ECPR).

DESIGN

The study authors performed a systematic review and meta-analysis of all available literature.

SETTING

The authors searched relevant databases (Pubmed, Medline, Embase) for studies measuring precannulation rSO₂ in patients undergoing ECPR and reporting mortality and/or neurologic outcomes.

PARTICIPANTS

The authors included both in-hospital and out-of-hospital cardiac arrest patients receiving ECPR. They identified 3 observational studies, including 245 adult patients.

INTERVENTIONS

The authors compared patients with a low precannulation rSO₂ (≤15% or 16%) versus patients with a high (>15% or 16%) precannulation rSO₂. In addition, the authors carried out subgroup analyses on out-of-hospital cardiac arrest (OHCA) patients.

MEASUREMENTS AND MAIN RESULTS

A high precannulation rSO₂ was associated with an overall reduced risk of mortality in ECPR recipients (98 out of 151 patients [64.9%] in the high rSO₂ group, v 87 out of 94 patients [92.5%] in the low rSO₂ group, risk differences [RD] -0.30; 95% CI -0.47 to -0.14), and in OHCA (78 out of 121 patients [64.5%] v 82 out of 89 patients [92.1%], RD 0.30; 95% CI -0.48 to -0.12). A high precannulation rSO₂ also was associated with a significantly better neurologic outcome in the overall population (42 out of 151 patients [27.8%] v 2 out of 94 patients [2.12%], RD 0.22; 95% CI 0.13-0.31), and in OHCA patients (33 out of 121 patients [27.3%] v 2 out of 89 patients [2.25%] RD 0.21; 95% CI 0.11-0.30).

CONCLUSIONS

A low rSO₂ before starting ECPR could be a predictor of mortality and survival with poor neurologic outcomes.

The effect of blood pressure on mortality following out-of-hospital cardiac arrest: a retrospective cohort study of the United Kingdom Intensive Care National Audit and Research Centre database

BACKGROUND

Hypotension following out-of-hospital cardiac arrest (OHCA) may cause secondary brain injury and increase mortality rates. Current guidelines recommend avoiding hypotension. However, the optimal blood pressure following OHCA is unknown. We hypothesised that exposure to hypotension and hypertension in the first 24 h in ICU would be associated with mortality following OHCA.

METHODS

We conducted a retrospective analysis of OHCA patients included in the Intensive Care National Audit and Research Centre Case Mix Programme from 1 January 2010 to 31 December 2019. Restricted cubic splines were created following adjustment for important prognostic variables. We report the adjusted odds ratio for associations between lowest and highest mean arterial pressure (MAP) and systolic blood pressure (SBP) in the first 24 h of ICU care and hospital mortality.

RESULTS

A total of 32,349 patients were included in the analysis. Hospital mortality was 56.2%. The median lowest and highest MAP and SBP were similar in survivors and non-survivors. Both hypotension and hypertension were associated with increased mortality. Patients who had a lowest recorded MAP in the range 60-63 mmHg had the lowest associated mortality. Patients who had a highest recorded MAP in the range 95-104 mmHg had the lowest associated mortality. The association between SBP and mortality followed a similar pattern to MAP.

CONCLUSIONS

We found an association between hypotension and hypertension in the first 24 h in ICU and mortality following OHCA. The inability to distinguish between the median blood pressure of survivors and non-survivors indicates the need for research into individualised blood pressure targets for survivors following OHCA.

Extracorporeal cardiopulmonary resuscitation (eCPR) and cerebral perfusion: A narrative review

Extracorporeal cardiopulmonary resuscitation (eCPR) is emerging as an effective, lifesaving resuscitation strategy for select patients with prolonged or refractory cardiac arrest. Currently, a paucity of evidence-based recommendations is available to guide clinical management of eCPR patients. Despite promising results from initial clinical trials, neurological injury remains a significant cause of morbidity and mortality. Neuropathology associated with utilization of an extracorporeal circuit may interact significantly with the consequences of a prolonged low-flow state that typically precedes eCPR. In this narrative review, we explore current gaps in knowledge about cerebral perfusion over the course of cardiac arrest and resuscitation with a focus on patients treated with eCPR. We found no studies which investigated regional cerebral blood flow or cerebral autoregulation in human cohorts specific to eCPR. Studies which assessed cerebral perfusion in clinical eCPR were small and limited to near-infrared spectroscopy. Furthermore, no studies prospectively or retrospectively evaluated the relationship between epinephrine and neurological outcomes in eCPR patients. In summary, the field currently lacks a comprehensive understanding of how regional cerebral perfusion and cerebral autoregulation are temporally modified by factors such as pre-eCPR low-flow duration, vasopressors, and circuit flow rate. Elucidating these critical relationships may inform future strategies aimed at improving neurological outcomes in patients treated with lifesaving eCPR.

Post-Cardiac Arrest: Mechanisms, Management, and Future Perspectives

Cardiac arrest is an important public health issue, with a survival rate of approximately 15 to 22%. A great proportion of these deaths occur after resuscitation due to post-cardiac arrest syndrome, which is characterized by the ischemia-reperfusion injury that affects the role body. Understanding physiopathology is mandatory to discover new treatment strategies and obtain better results. Besides improvements in cardiopulmonary resuscitation maneuvers, the great increase in survival rates observed in recent decades is due to new approaches to post-cardiac arrest care. In this review, we will discuss physiopathology, etiologies, and post-resuscitation care, emphasizing targeted temperature management, early coronary angiography, and rehabilitation.

Extracorporeal Cardiopulmonary Resuscitation: A Narrative Review and Establishment of a Sustainable Program

The rates of survival with functional recovery for out of hospital cardiac arrest remain unacceptably low. Extracorporeal cardiopulmonary resuscitation (ECPR) quickly resolves the low-flow state of conventional cardiopulmonary resuscitation (CCPR) providing valuable perfusion to end organs. Observational studies have shown an association with the use of ECPR and improved survivability. Two recent randomized controlled studies have demonstrated improved survival with functional neurologic recovery when compared to CCPR. Substantial resources and coordination amongst different specialties and departments are crucial for the successful implementation of ECPR. Standardized protocols, simulation based training, and constant communication are invaluable to the sustainability of a program. Currently there is no standardized protocol for the post-cannulation management of these ECPR patients and, ideally, upcoming studies should aim to evaluate these protocols.

Cerebral multimodality monitoring in adult neurocritical care patients with acute brain injury: A narrative review

Cerebral multimodality monitoring (MMM) is, even with a general lack of Class I evidence, increasingly recognized as a tool to support clinical decision-making in the neuroscience intensive care unit (NICU). However, literature and guidelines have focused on unimodal signals in a specific form of acute brain injury. Integrating unimodal signals in multiple signal monitoring is the next step for clinical studies and patient care. As such, we aimed to investigate the recent application of MMM in studies of adult patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH), acute ischemic stroke (AIS), and hypoxic ischemic brain injury following cardiac arrest (HIBI). We identified continuous or daily updated monitoring modalities and summarized the monitoring setting, study setting, and clinical characteristics. In addition, we discussed clinical outcome in intervention studies. We identified 112 MMM studies, including 11 modalities, over the last 7 years (2015-2022). Fifty-eight studies (52%) applied only two modalities. Most frequently combined were ICP monitoring (92 studies (82%)) together with PbtO₂ (63 studies (56%). Most studies included patients with TBI (59 studies) or SAH (53 studies). The enrollment period of 34 studies (30%) took more than 5 years, whereas the median sample size was only 36 patients (q1- q3, 20-74). We classified studies as either observational (68 studies) or interventional (44 studies). The interventions were subclassified as systemic (24 studies), cerebral (10 studies), and interventions guided by MMM (11 studies). We identified 20 different systemic or cerebral interventions. Nine (9/11, 82%) of the MMM-guided studies included clinical outcome as an endpoint. In 78% (7/9) of these MMM-guided intervention studies, a significant improvement in outcome was demonstrated in favor of interventions guided by MMM. Clinical outcome may be improved with interventions guided by MMM. This strengthens the belief in this application, but further interdisciplinary collaborations are needed to overcome the heterogeneity, as illustrated in the present review. Future research should focus on increasing sample sizes, improved data collection, refining definitions of secondary injuries, and standardized interventions. Only then can we proceed with complex outcome studies with MMM-guided treatment.

Interactions in the 2×2×2 factorial randomised clinical STEPCARE trial and the potential effects on conclusions: a protocol for a simulation study

Background

Randomised clinical trials with a factorial design may assess the effects of multiple interventions in the same population. Factorial trials are carried out under the assumption that the trial interventions have no interactions on outcomes. Here, we present a protocol for a simulation study investigating the consequences of different levels of interactions between the trial interventions on outcomes for the future 2×2×2 factorial designed randomised clinical Sedation, TEmperature, and Pressure after Cardiac Arrest and REsuscitation (STEPCARE) trial in comatose patients after out-of-hospital cardiac arrest.

Methods

By simulating a multisite trial with 50 sites and 3278 participants, and a presumed six-month all-cause mortality of 60% in the control population, we will investigate the validity of the trial results with different levels of interaction effects on the outcome. The primary simulation outcome of the study is the risks of type-1 and type-2 errors in the simulated scenarios, i.e. at what level of interaction is the desired alpha and beta level exceeded. When keeping the overall risk of type-1 errors ≤ 5% and the risk of type-2 errors ≤ 10%, we will quantify the maximum interaction effect we can accept if the planned sample size is increased by 5% to take into account possible interaction between the trial interventions. Secondly, we will assess how interaction effects influence the minimal detectable difference we may confirm or reject to take into account 5% (small interaction effect), 10% (moderate), or 15% (large) positive interactions in simulations with no ‘true’ intervention effect (type-1 errors) and small (5%), moderate (10%), or large negative interactions (15%) in simulations with ‘true’ intervention effects (type-2 errors). Moreover, we will investigate how much the sample size must be increased to account for a small, moderate, or large interaction effects.

Discussion

This protocol for a simulation study will inform the design of a 2×2×2 factorial randomised clinical trial of how potential interactions between the assessed interventions might affect conclusions. Protocolising this simulation study is important to ensure valid and unbiased results.

Trial registration

Not relevant

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06796-7.

Blood-Pressure Targets in Comatose Survivors of Cardiac Arrest

BACKGROUND

Evidence to support the choice of blood-pressure targets for the treatment of comatose survivors of out-of-hospital cardiac arrest who are receiving intensive care is limited.

METHODS

In a double-blind, randomized trial with a 2-by-2 factorial design, we evaluated a mean arterial blood-pressure target of 63 mm Hg as compared with 77 mm Hg in comatose adults who had been resuscitated after an out-of-hospital cardiac arrest of presumed cardiac cause; patients were also assigned to one of two oxygen targets (reported separately). The primary outcome was a composite of death from any cause or hospital discharge with a Cerebral Performance Category (CPC) of 3 or 4 within 90 days (range, 0 to 5, with higher categories indicating more severe disability; a category of 3 or 4 indicates severe disability or coma). Secondary outcomes included neuron-specific enolase levels at 48 hours, death from any cause, scores on the Montreal Cognitive Assessment (range, 0 to 30, with higher scores indicating better cognitive ability) and the modified Rankin scale (range, 0 to 6, with higher scores indicating greater disability) at 3 months, and the CPC at 3 months.

RESULTS

A total of 789 patients were included in the analysis (393 in the high-target group and 396 in the low-target group). A primary-outcome event occurred in 133 patients (34%) in the high-target group and in 127 patients (32%) in the low-target group (hazard ratio, 1.08; 95% confidence interval [CI], 0.84 to 1.37; P = 0.56). At 90 days, 122 patients (31%) in the high-target group and 114 patients (29%) in the low-target group had died (hazard ratio, 1.13; 95% CI, 0.88 to 1.46). The median CPC was 1 (interquartile range, 1 to 5) in both the high-target group and the low-target group; the corresponding median modified Rankin scale scores were 1 (interquartile range, 0 to 6) and 1 (interquartile range, 0 to 6), and the corresponding median Montreal Cognitive Assessment scores were 27 (interquartile range, 24 to 29) and 26 (interquartile range, 24 to 29). The median neuron-specific enolase level at 48 hours was also similar in the two groups. The percentages of patients with adverse events did not differ significantly between the groups.

CONCLUSIONS

Targeting a mean arterial blood pressure of 77 mm Hg or 63 mm Hg in patients who had been resuscitated from cardiac arrest did not result in significantly different percentages of patients dying or having severe disability or coma. (Funded by the Novo Nordisk Foundation; BOX ClinicalTrials.gov number, NCT03141099.).