Changing target temperature from 33 °C to 36 °C in the ICU management of out-of-hospital cardiac arrest: A before and after study

Practice survey on recent changes in post cardiac arrest care and temperature management in French intensive care units

BACKGROUND

Recent guidelines for post-cardiac arrest (CA) management have undergone significant changes regarding targeted therapeutic management (TTM), transitioning from hypothermia to temperature control. We aimed to assess changes in post-CA management in French intensive care units following the new recommendations.

METHODS

Two declarative web surveys were conducted from March to August 2023. We compared the doctors' survey to that previously published in 2015. We contacted 389 departments from 276 French centers.

RESULTS

Three hundred thirty-four physicians from 189 distinct ICUs departments participated in the survey. TTM was used by 95.5 % of respondents. TTM with temperature feedback device was used by 64 % of respondents. In multivariate analysis, use of TTM with temperature feedback was associated with university hospital responder [OR 1.99 (1.19-3.34, p = 0.009)], high CA admissions rate [OR 2.25 (1.13-4.78, p = 0.026)], use of a written CA procedure [OR 1.76 (1.07-2.92, p = 0.027)] and presence of a cath-lab performing coronary angiography [OR 2.42 (1.33-4.44, p = 0.004)]. The targeted temperature rose from 32 to 34 °C in 2015, to 35-36 °C in 2023 (p < 0.001). Proportions of TTM with temperature feedback devices switched from 45 % to 65 % (p < 0.001). 660 nurses responses from 150 ICUs were analyzed. According to TTM users, gel-coated water circulating pads and intravascular cooling were considered the most effective devices and were found to be easily adjustable.

CONCLUSIONS

These surveys provide insights into post-resuscitation care and TTM practice in France. One year after their publication, the latest recommendations concerning TTM have not been fully implemented, as the majority of ICUs continue to use moderate hypothermia. They widely reported employing specific TTM, with the use of TTM with temperature feedback devices increasing significantly. Heterogeneity exists regarding the TTM systems used, with a significant proportion lacking temperature feedback. This aspect requires specific attention, depending on local constraints and devices costs.

Does targeted temperature management at 33 °C improve outcome after cardiac arrest?

PURPOSE OF REVIEW

Following successful resuscitation from cardiac arrest, a complex set of pathophysiologic processes are acutely triggered, leading to substantial morbidity and mortality. Postarrest management remains a major challenge to critical care providers, with few proven therapeutic strategies to improve outcomes. One therapy that has received substantial focus is the intentional lowering of core body temperature for a discrete period of time following resuscitation. In this review, we will discuss the key trials and other evidence surrounding TTM and present opposing arguments, one 'against' the use of postarrest TTM and another 'for' the use of this therapeutic approach.

RECENT FINDINGS

Targeted temperature management, has been a topic of enormous controversy, as recently a number of clinical trials show conflicting results on the effect of TTM. Fundamental questions, about the dosing of TTM (e.g. use at 33 °C versus higher temperatures), or the use of TTM at all (as opposed to passive fever avoidance), remain active topics of global discussion. Systematic reviews on this topic also show variable results.

SUMMARY

There are several arguments for and against the use of TTM targeting 33 °C for alleviating brain injury after cardiac arrest. More studies are on the way that will hopefully provide more robust evidence and hopefully allow for consensus on this important topic.

Mild therapeutic hypothermia after cardiac arrest - effect on survival with good neurological outcome outside of randomised controlled trials: A registry-based analysis

BACKGROUND

For nearly 20 years, in international guidelines, mild therapeutic hypothermia (MTH) was an important component of postresuscitation care. However, recent randomised controlled trials have questioned its benefits. At present, international guidelines only recommend actively preventing fever, but there are ongoing discussions about whether the majority of cardiac arrest patients could benefit from MTH treatment.

OBJECTIVE

The aim of this study was to compare the outcome of adult patients treated with and without MTH after cardiac arrest.

DESIGN

Observational cohort study.

SETTING

German Resuscitation Registry covering more than 31 million inhabitants of Germany and Austria.

PATIENTS

All adult patients between 2006 and 2022 with out-of-hospital or in-hospital cardiac arrest and comatose on admission.

MAIN OUTCOME MEASURES

Primary endpoint: hospital discharge with good neurological outcome [cerebral performance categories (CPC) 1 or 2]. Secondary endpoint: hospital discharge. We used a multivariate binary logistic regression analysis to identify the effects on outcome of all known influencing variables.

RESULTS

We analysed 33 933 patients (10 034 treated with MTH, 23 899 without MTH). The multivariate regression model revealed that MTH was an independent predictor of CPC 1/2 survival and of hospital discharge with odds ratio (95% confidence intervals) of 1.60 (1.49 to 1.72), P < 0.001 and 1.89 (1.76 to 2.02), P < 0.001, respectively.

CONCLUSION

Our data indicate the existence of a positive association between MTH and a favourable neurological outcome after cardiac arrest. It therefore seems premature to refrain from giving MTH treatment for the entire spectrum of patients after cardiac arrest. Further prospective studies are needed.

Influence of Cooling duration on Efficacy in Cardiac Arrest Patients (ICECAP): study protocol for a multicenter, randomized, adaptive allocation clinical trial to identify the optimal duration of induced hypothermia for neuroprotection in comatose, adult survivors of after out-of-hospital cardiac arrest

BACKGROUND

Cardiac arrest is a common and devastating emergency of both the heart and brain. More than 380,000 patients suffer out-of-hospital cardiac arrest annually in the USA. Induced cooling of comatose patients markedly improved neurological and functional outcomes in pivotal randomized clinical trials, but the optimal duration of therapeutic hypothermia has not yet been established.

METHODS

This study is a multi-center randomized, response-adaptive, duration (dose) finding, comparative effectiveness clinical trial with blinded outcome assessment. We investigate two populations of adult comatose survivors of cardiac arrest to ascertain the shortest duration of cooling that provides the maximum treatment effect. The design is based on a statistical model of response as defined by the primary endpoint, a weighted 90-day mRS (modified Rankin Scale, a measure of neurologic disability), across the treatment arms. Subjects will initially be equally randomized between 12, 24, and 48 h of therapeutic cooling. After the first 200 subjects have been randomized, additional treatment arms between 12 and 48 h will be opened and patients will be allocated, within each initial cardiac rhythm type (shockable or non-shockable), by response adaptive randomization. As the trial continues, shorter and longer duration arms may be opened. A maximum sample size of 1800 subjects is proposed. Secondary objectives are to characterize: the overall safety and adverse events associated with duration of cooling, the effect on neuropsychological outcomes, and the effect on patient-reported quality of life measures.

DISCUSSION

In vitro and in vivo studies have shown the neuroprotective effects of therapeutic hypothermia for cardiac arrest. We hypothesize that longer durations of cooling may improve either the proportion of patients that attain a good neurological recovery or may result in better recovery among the proportion already categorized as having a good outcome. If the treatment effect of cooling is increasing across duration, for at least some set of durations, then this provides evidence of the efficacy of cooling itself versus normothermia, even in the absence of a normothermia control arm, confirming previous RCTs for OHCA survivors of shockable rhythms and provides the first prospective controlled evidence of efficacy in those without initial shockable rhythms.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04217551. Registered on 30 December 2019.

Temperature Control in the Era of Personalized Medicine: Knowledge Gaps, Research Priorities, and Future Directions

Hypoxic-ischemic brain injury (HIBI) is the leading cause of death and disability after cardiac arrest. To date, temperature control is the only intervention shown to improve neurologic outcomes in patients with HIBI. Despite robust preclinical evidence supporting hypothermia as neuroprotective therapy after cardiac arrest, there remains clinical equipoise regarding optimal core temperature, therapeutic window, and duration of therapy. Current guidelines recommend continuous temperature monitoring and active fever prevention for at least 72 h and additionally note insufficient evidence regarding temperature control targeting 32 °C-36 °C. However, population-based thresholds may be inadequate to support the metabolic demands of ischemic, reperfused, and dysregulated tissue. Promoting a more personalized approach with individualized targets has the potential to further improve outcomes. This review will analyze current knowledge and evidence, address research priorities, explore the components of high-quality temperature control, and define critical future steps that are needed to advance patient-centered care for cardiac arrest survivors.

Postarrest Care Bundle Improves Quality of Care and Clinical Outcomes in the Normothermia Era

PURPOSE

Temperature targets in patients with cardiac arrest and return of spontaneous circulation (ROSC) have changed. Changes to higher temperature targets have been associated with higher breakthrough fevers and mortality. A post-ROSC normothermia bundle was developed to improve compliance with temperature targets.

METHODS

In August 2021, "ad hoc" normothermia at the discretion of the attending intensivist was initiated. In December 2021, a post-ROSC normothermia protocol was implemented, incorporating a rigorous, stepwise approach to fever prevention (temperature ≥ 37.8). We conducted a before-after cohort study of all adult patients post-ROSC who survived to intensive care unit admission between August 1, 2021, and April 1, 2022. They were divided into "ad hoc" and "protocol" groups. Clinical outcomes compared included fevers, active cooling, and paralytic use.

RESULTS

Fifty-eight post-ROSC patients were admitted; 24 in the "ad hoc" and 34 in the "protocol" groups. Patient demographics were similar between groups. The "ad hoc" group had more shockable rhythms (67% vs 24%, P = .001) and cardiac catheterizations (42% vs 15%, P = .03). The "protocol" group were significantly less likely to have a fever at 40 h (6% vs 40%, P < .001) and 72 h (14% vs 65%, P ≤ .001). Patients in the normothermia "protocol" used significantly less neuromuscular blocking agents (24% vs 50%, P = .05). The normothermia "protocol" resulted in similar mortality (56% vs 58%, P = 1.0).

CONCLUSION

Use of a normothermia "protocol" resulted in fewer fevers and less neuromuscular blocker administration compared to "ad hoc" management. A protocolized approach for improved quality of care should be considered in institutions adopting normothermia.

Influence of Cooling duration on Efficacy in Cardiac Arrest Patients (ICECAP): study protocol for a multicenter, randomized, adaptive allocation clinical trial to identify the optimal duration of induced hypothermia for neuroprotection in comatose, adult survivors of after out-of-hospital cardiac arrest

Background

Cardiac arrest is a common and devastating emergency of both the heart and brain. More than 380,000 patients suffer out-of-hospital cardiac arrest annually in the United States. Induced cooling of comatose patients markedly improved neurological and functional outcomes in pivotal randomized clinical trials, but the optimal duration of therapeutic hypothermia has not yet been established.

Methods

This study is a multi-center randomized, response-adaptive, duration (dose) finding, comparative effectiveness clinical trial with blinded outcome assessment. We investigate two populations of adult comatose survivors of cardiac arrest to ascertain the shortest duration of cooling that provides the maximum treatment effect. The design is based on a statistical model of response as defined by the primary endpoint, a weighted 90-day mRS (modified Rankin Scale, a measure of neurologic disability), across the treatment arms. Subjects will initially be equally randomized between 12, 24, and 48 hours of therapeutic cooling. After the first 200 subjects have been randomized, additional treatment arms between 12 and 48 hours will be opened and patients will be allocated, within each initial cardiac rhythm type (shockable or non-shockable), by response adaptive randomization. As the trial continues, shorter and longer duration arms may be opened. A maximum sample size of 1800 subjects is proposed. Secondary objectives are to characterize: the overall safety and adverse events associated with duration of cooling, the effect on neuropsychological outcomes, and the effect on patient reported quality of life measures.

Discussion

In-vitro and in-vivo studies have shown the neuroprotective effects of therapeutic hypothermia for cardiac arrest. We hypothesize that longer durations of cooling may improve either the proportion of patients that attain a good neurological recovery or may result in better recovery among the proportion already categorized as having a good outcome. If the treatment effect of cooling is increasing across duration, for at least some set of durations, then this provides evidence of the efficacy of cooling itself versus normothermia, even in the absence of a normothermia control arm, confirming previous RCTs for OHCA survivors of shockable rhythms and provides the first prospective controlled evidence of efficacy in those without initial shockable rhythms.

Trial registration

ClinicalTrials.gov (NCT04217551, 2019-12-30).

Temperature Control in Acute Brain Injury: An Update

Temperature control in severe acute brain injury (SABI) is a key component of acute management. This manuscript delves into the complex role of temperature management in SABI, encompassing conditions like traumatic brain injury (TBI), acute ischemic stroke (AIS), intracerebral hemorrhage (ICH), aneurysmal subarachnoid hemorrhage (aSAH), and hypoxemic/ischemic brain injury following cardiac arrest. Fever is a common complication in SABI and is linked to worse neurological outcomes due to increased inflammatory responses and intracranial pressure (ICP). Temperature management, particularly hypothermic temperature control (HTC), appears to mitigate these adverse effects primarily by reducing cerebral metabolic demand and dampening inflammatory pathways. However, the effectiveness of HTC varies across different SABI conditions. In the context of post-cardiac arrest, the impact of HTC on neurological outcomes has shown inconsistent results. In cases of TBI, HTC seems promising for reducing ICP, but its influence on long-term outcomes remains uncertain. For AIS, clinical trials have yet to conclusively demonstrate the benefits of HTC, despite encouraging preclinical evidence. This variability in efficacy is also observed in ICH, aSAH, bacterial meningitis, and status epilepticus. In pediatric and neonatal populations, while HTC shows significant benefits in hypoxic-ischemic encephalopathy, its effectiveness in other brain injuries is mixed. Although the theoretical basis for employing temperature control, especially HTC, is strong, the clinical outcomes differ among various SABI subtypes. The current consensus indicates that fever prevention is beneficial across the board, but the application and effectiveness of HTC are more nuanced, underscoring the need for further research to establish optimal temperature management strategies. Here we provide an overview of the clinical evidence surrounding the use of temperature control in various types of SABI.

A Systematic Literature Review to Assess Fever Management and the Quality of Targeted Temperature Management in Critically Ill Patients

Targeted temperature management (TTM) has been proposed to reduce mortality and improve neurological outcomes in postcardiac arrest and other critically ill patients. TTM implementation may vary considerably among hospitals, and "high-quality TTM" definitions are inconsistent. This systematic literature review in relevant critical care conditions evaluated the approaches to and definitions of TTM quality with respect to fever prevention and the maintenance of precise temperature control. Current evidence on the quality of fever management associated with TTM in cardiac arrest, traumatic brain injury, stroke, sepsis, and critical care more generally was examined. Searches were conducted in Embase and PubMed (2016 to 2021) following PRISMA guidelines. In total, 37 studies were identified and included, with 35 focusing on postarrest care. Frequently-reported TTM quality outcomes included the number of patients with rebound hyperthermia, deviation from target temperature, post-TTM body temperatures, and number of patients achieving target temperature. Surface and intravascular cooling were used in 13 studies, while one study used surface and extracorporeal cooling and one study used surface cooling and antipyretics. Surface and intravascular methods had comparable rates of achieving target temperature and maintaining temperature. A single study showed that patients with surface cooling had a lower incidence of rebound hyperthermia. This systematic literature review largely identified cardiac arrest literature demonstrating fever prevention with multiple TTM approaches. There was substantial heterogeneity in the definitions and delivery of quality TTM. Further research is required to define quality TTM across multiple elements, including achieving target temperature, maintaining target temperature, and preventing rebound hyperthermia.

Characterizing the impact of thermoregulation in patients after cardiac arrest: a retrospective cohort study

PURPOSE

Core body temperature has been extensively investigated as a thereuptic target in care after cardiac arrest. Nevertheless, the integrity of thermoregulation in patients after cardiac arrest has not been well studied. We sought to evaluate whether low spontaneous body temperature after cardiac arrest is associated with increased death and a worse neurologic outcome, and whether patients with low spontaneous body temperature exhibit features suggestive of impaired thermoregulation.

METHODS

We conducted a single-centre retrospective cohort study. We included all adult patients who underwent temperature control with hypothermia after cardiac arrest between 1 January 2014 and 30 June 2020. The primary exposure was low spontaneous core body temperature (< 35 °C) at initiation of hypothermia therapy. The primary outcome was in-hospital death and the secondary outcome was poor neurologic outcomes at discharge.

RESULTS

Five hundred and ninety-seven adult patients, comprising both in- and out-of-hospital cardiac arrests, were included. Patients with low spontaneous body temperature also had slightly lower average temperature, and more frequent transient but controlled breakthrough fever episodes in the first 24 hr. In the multivariable logistic regression analysis, low spontaneous body temperature was associated with higher odds of in-hospital death (odds ratio, 2.9; 95% confidence interval, 1.9 to 4.2; P < 0.001).

CONCLUSION

In this single-centre retrospective cohort study, low spontaneous core body temperature was associated with poor outcomes in patients after cardiac arrest. Patients with low spontaneous body temperature also exhibited features suggestive of impaired thermoregulation. Further research is needed to determine whether body temperature upon presentation reflects the robustness of the patient's underlying physiology and severity of brain insult after a cardiac arrest.

Cooling Under a Blanketrol System Versus Cooling With an Arctic Sun Thermoregulation System (CATS) for Neonates Undergoing Therapeutic Hypothermia

Background Despite evidence suggesting improved outcomes in neonates with hypoxic-ischemic encephalopathy (HIE) treated with therapeutic hypothermia (TH), data on the impact of temperature variability during cooling and its association with clinical outcomes remain limited. Objective To compare the efficacy and ease of use of two different cooling systems, the Arctic Sun (Medivance, Inc., Louisville, CO) vs. the Blanketrol III (Gentherm Medical, Cincinnati, OH) on achieving TH, temperature variability, and clinical outcomes in neonates with HIE undergoing TH. Methods This study was conducted at the Baylor Scott and White Medical Center's Level IV NICU. The study employed a retrospective cohort design, comparing infants treated with the Arctic Sun device (from December 2020 to August 2021) to a historical cohort treated with the Blanketrol system (from January 2017 to November 2020). Both groups were evaluated for clinical characteristics, patients' outcomes, and ease of use of the cooling devices. Ease of use was assessed through a self-developed survey administered to NICU nurses. Core body temperatures throughout the cooling course were documented at four-hour intervals, including induction, maintenance, and rewarming phases. Results Twenty-two infants were cooled using the Arctic Sun system, and 44 infants were cooled with the Blanketrol device. Median birth weight and gestational age were comparable. There were no significant differences in one-minute and five-minute appearance, pulse, grimace, activity, and respiration (APGAR) scores. The Arctic Sun group had a significantly higher rate of maternal morbidities, including diabetes and placental abruption. Although the median temperature achieved with both devices was 33.5°C, temperature variability was significantly greater with the Blanketrol device (p = 0.03). Thrombocytopenia rates were statistically different between the groups (9% in Arctic Sun vs. 38% in Blanketrol, p = 0.001). Although the Blanketrol group had higher rates of disseminated intravascular coagulation (48% vs. 37%), hypercalcemia (23% vs. 5%), and subcutaneous fat necrosis (7% vs. 5%), these differences were not statistically significant. A nurses' survey on ease of use revealed a strong preference for the Arctic Sun cooling system. Over 85% of nurses found it easier to learn and set up and required less manual intervention than the Blanketrol device. Conclusions Gel adhesive pad-based TH is a potentially superior modality to traditional water-circulating cooling devices. These pads offer advantages in user-friendliness, improved temperature control precision, and potentially reduced adverse event profiles.

Review of Temperature Management in Traumatic Brain Injuries

Therapeutic hypothermia (TH) for severe traumatic brain injury has seen restricted application due to the outcomes of randomized controlled trials (RCTs) conducted since 2000. In contrast with earlier RCTs, recent trials have implemented active normothermia management in control groups, ensuring comparable intensities of non-temperature-related therapeutic interventions, such as neurointensive care. This change in approach may be a contributing factor to the inability to establish the efficacy of TH. Currently, an active temperature management method using temperature control devices is termed "targeted temperature management (TTM)". One of the goals of TTM for severe traumatic brain injury is the regulation of increased intracranial pressure, employing TTM as a methodology for intracranial pressure management. Additionally, fever in traumatic brain injury has been acknowledged as contributing to poor prognosis, underscoring the importance of proactively preventing fever. TTM is also employed for the preemptive prevention of fever in severe traumatic brain injury. As an integral component of current neurointensive care, it is crucial to precisely delineate the targets of TTM and to potentially apply them in the treatment of severe traumatic brain injury.

Systematic Literature Review of the Association of Fever and Elevated Temperature with Outcomes in Critically Ill Adult Patients

Although most commonly associated with infection, elevated temperature and fever also occur in a variety of critically ill populations. Prior studies have suggested that fever and elevated temperature may be detrimental to critically ill patients and can lead to poor outcomes, but the evidence surrounding the association of fever with outcomes is rapidly evolving. To broadly assess potential associations of elevated temperature and fever with outcomes in critically ill adult patients, we performed a systematic literature review focusing on traumatic brain injury, stroke (ischemic and hemorrhagic), cardiac arrest, sepsis, and general intensive care unit (ICU) patients. Searches were conducted in Embase® and PubMed® from 2016 to 2021, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, including dual-screening of abstracts, full texts, and extracted data. In total, 60 studies assessing traumatic brain injury and stroke (24), cardiac arrest (8), sepsis (22), and general ICU (6) patients were included. Mortality, functional, or neurological status and length of stay were the most frequently reported outcomes. Elevated temperature and fever were associated with poor clinical outcomes in patients with traumatic brain injury, stroke, and cardiac arrest but not in patients with sepsis. Although a causal relationship between elevated temperature and poor outcomes cannot be definitively established, the association observed in this systematic literature review supports the concept that management of elevated temperature may factor in avoidance of detrimental outcomes in multiple critically ill populations. The analysis also highlights gaps in our understanding of fever and elevated temperature in critically ill adult patients.

Factors influencing deviation from target temperature during targeted temperature management in postcardiac arrest patients

BACKGROUND

Targeted temperature management (TTM) is a recommended therapy for postcardiac arrest patients. Hyperthermia worsened the patient outcome, and overcooling increased the incidence of complications; therefore, a high-quality TTM is required. The target temperature tended to be modified worldwide after the TTM trial in 2013. Our institute modified the target temperature to 35°C in 2017. This study aimed to compare the conventional and modified protocols, assess the relationship between target temperature deviation and patient outcomes, and identify the factors influencing temperature deviation.

METHODS

This single-centre, retrospective, observational study included adult out-of-hospital cardiac arrest patients who underwent TTM between April 2013 and October 2019. We compared the conventional and modified protocol groups to evaluate the difference in the background characteristics and details on TTM. Subsequently, we assessed the relationship of deviation (>±0.5°C, >37°C, or<33°C) rates from the target temperature with mortality and neurological outcomes. We assessed the factors that influenced the deviation from the target temperature.

RESULTS

Temperature deviation was frequently observed in the conventional protocol group (p=0.012), and the modified protocol group required higher doses of neuromuscular blocking agents (NMBAs) during TTM (p=0.016). Other background data, completion of protocol, incidence of complications, mortality and rate of favourable neurological outcomes were not significantly different. The performance rate of TTM was significantly higher in the modified group than in the conventional protocol group (p<0.001). Temperature deviation did not have an impact on the outcomes. Age, sex, body surface area, NMBA doses and type of cooling device were the factors influencing temperature deviation.

CONCLUSIONS

A target temperature of 35°C might be acceptable and easily attainable if shivering of the patients was well controlled using NMBAs. Temperature deviation did not have an impact on outcomes. The identified factors influencing deviation from target temperature might be useful for ensuring a high-quality TTM.

Post-cardiac arrest intensive care in Sweden: A survey of current clinical practice

BACKGROUND

European guidelines recommend targeted temperature management (TTM) in post-cardiac arrest care. A large multicentre clinical trial, however, showed no difference in mortality and neurological outcome when comparing hypothermia to normothermia with early treatment of fever. The study results were valid given a strict protocol for the assessment of prognosis using defined neurological examinations. With the current range of recommended TTM temperatures, and applicable neurological examinations, procedures may differ between hospitals and the variation of clinical practice in Sweden is not known.

AIM

The aim of this study was to investigate current practice in post-resuscitation care after cardiac arrest as to temperature targets and assessment of neurological prognosis in Swedish intensive care units (ICUs).

METHODS

A structured survey was conducted by telephone or e-mail in all Levels 2 and 3 (= 53) Swedish ICUs during the spring of 2022 with a secondary survey in April 2023.

RESULTS

Five units were not providing post-cardiac arrest care and were excluded. The response rate was 43/48 (90%) of the eligible units. Among the responding ICUs, normothermia (36-37.7°C) was applied in all centres (2023). There was a detailed routine for the assessment of neurological prognosis in 38/43 (88%) ICUs. Neurological assessment was applied 72-96 h after return of spontaneous circulation in 32/38 (84%) units. Electroencephalogram and computed tomography and/or magnetic resonance imaging were the most common technical methods available.

CONCLUSION

Swedish ICUs use normothermia including early treatment of fever in post-resuscitation care after cardiac arrest and almost all apply a detailed routine for the assessment of neurological prognosis. However, available methods for prognostic evaluation varies between hospitals.

Temperature Management for Comatose Adult Survivors of Cardiac Arrest: A Science Advisory From the American Heart Association

Targeted temperature management has been a cornerstone of post-cardiac arrest care for patients remaining unresponsive after return of spontaneous circulation since the initial trials in 2002 found that mild therapeutic hypothermia improves neurological outcome. The suggested temperature range expanded in 2015 in response to a large trial finding that outcomes were not better with treatment at 33° C compared with 36° C. In 2021, another large trial was published in which outcomes with temperature control at 33° C were not better than those of patients treated with a strategy of strict normothermia. On the basis of these new data, the International Liaison Committee on Resuscitation and other organizations have altered their treatment recommendations for temperature management after cardiac arrest. The new American Heart Association guidelines on this topic will be introduced in a 2023 focused update. To provide guidance to clinicians while this focused update is forthcoming, the American Heart Association's Emergency Cardiovascular Care Committee convened a writing group to review the TTM2 trial (Hypothermia Versus Normothermia After Out-of-Hospital Cardiac Arrest) in the context of other recent evidence and to present an opinion on how this trial may influence clinical practice. This science advisory was informed by review of the TTM2 trial, consideration of other recent influential studies, and discussion between cardiac arrest experts in the fields of cardiology, critical care, emergency medicine, and neurology. Conclusions presented in this advisory statement do not replace current guidelines but are intended to provide an expert opinion on novel literature that will be incorporated into future guidelines and suggest the opportunity for reassessment of current clinical practice.

Target temperature in post-arrest comatous patients. Is something changed in the postpandemic era?

INTRODUCTION

The recommended target temperature in the treatment of comatous patients after cardiac arrest has recently changed. We analyzed the impact on the neurological outcome of a change in the target temperature from July 2021.

MATERIAL AND METHODS

This was a retrospective analysis comparing the discharge status of 78 patients with a target temperature of 33 °C (group 1) with that of 24 patients with a target temperature of 36.5 °C (group 2). Pearson chi-square and Mann-Whitney U tests were used.

RESULTS

The initial rhythm was defibrillable in 65% of group 1 and 71% of group 2, and cardiac arrest was witnessed in 93% of group 1 and 96% of group 2. There was an adverse outcome (death or vegetative state) in 37 patients in group 1 (47%) compared to 18 in group 2 (74%) (Pearson chi-square 5.612, p = 0.018).

CONCLUSIONS

In our series of patients, the temperature control target temperature change from 33 °C to 36.5 °C was associated with worse neurological outcome. Further studies are needed to evaluate the outcome of a generalized modification of temperature control targets in comatose patients after cardiac arrest in our postpandemic era.

Change of target temperature from 36°C to strict fever avoidance only in comatose cardiac arrest survivors - A before and after study

AIM

The guidelines on temperature control for comatose cardiac arrest survivors were recently changed from recommending targeted temperature management (32-36°C) to fever control (≤37.7℃). We investigated the effect of implementing a strict fever control strategy on prevalence of fever, protocol adherence, and patient outcome in a Finnish tertiary academic hospital.

METHODS

Comatose cardiac arrest survivors treated with either mild device-controlled therapeutic hypothermia (≤36℃, years 2020-2021) or strict fever control (≤37℃, year 2022) for the first 36h were included in this before-after cohort study. Good neurological outcome was defined as a cerebral performance category score of 1-2.

RESULTS

The cohort consisted of 120 patients (≤36℃ group n=77, ≤37℃ group n=43). Cardiac arrest characteristics, severity of illness scores, and intensive care management including oxygenation, ventilation, blood pressure management and lactate remained similar between the groups. The median highest temperatures for the 36h sedation period were 36.3℃ (≤36℃ group) vs. 37.2℃ (≤37℃ group) (p<0.001). Time of the 36h sedation period spent >37.7℃ was 0.90% vs. 1.1% (p=0.496). External cooling devices were used in 90% vs. 44% of the patients (p<0.001). Good neurological outcome at 30 days was similar between the groups (47% vs. 44%, p=0.787). In multivariable model the ≤37℃ strategy was not associated with any change in outcome (OR 0.88, 95% CI 0.33-2.3).

CONCLUSIONS

The implementation strict fever control strategy was feasible and did not result in increased prevalence of fever, poorer protocol adherence, or worse patient outcomes. Most patients in the fever control group did not require external cooling.

Therapeutic Hypothermia Following Cardiac Arrest After the TTM2 trial - More Questions Raised Than Answered

For almost 20 years, therapeutic hypothermia has been a cornerstone of modern post-cardiac arrest care lowering mortality, and improvin neurologic outcome compared to conventional therapy. This was challenged by the first TTM-trial in 2013, which did not show a benefit for hypothermia at 33°C compared to controlled normothermia at 36°C. Now, the TTM2 trial showed no benefit of hypothermia compared to fever prevention alone. While TTM1 and TTM2 suggest that hypothermia might not be helpful, a deep dive into the trials reveals that this conclusion does not hold true. Here, we focus on patient selection, suboptimal application of hypothermia, interaction of standard sedation with hypothermia, high incidence of post-arrest fever, and withdrawal of life support based on per-protocol neurologic prognostication in the TTM2-trial. Of particular interest, contemporary trials and registries using intravascular cooling in TTM-like patients repeatedly reported much lower mortality rates than those described in both TTM1 and TTM2.

Targeted temperature management with hypothermia for comatose patients after cardiac arrest

Targeted temperature management with mild hypothermia (TTM-hypothermia; 32-34 °C) is a treatment strategy for adult patients who are comatose after cardiac arrest. Robust preclinical data support the beneficial effects of hypothermia beginning within 4 hours of reperfusion and maintained during the several days of postreperfusion brain dysregulation. TTM-hypothermia increased survival and functional recovery after adult cardiac arrest in several trials and in realworld implementation studies. TTM-hypothermia also benefits neonates with hypoxic-ischemic brain injury. However, larger and methodologically more rigorous adult trials do not detect benefit. Reasons for inconsistency of adult trials include the difficulty delivering differential treatment between randomized groups within 4 hours and the use of shorter durations of treatment. Furthermore, adult trials enrolled populations that vary in illness severity and brain injury, with individual trials enriched for higher or lower illness severity. There are interactions between illness severity and treatment effect. Current data indicate that TTM-hypothermia implemented quickly for adult patients after cardiac arrest, may benefit select patients at risk of severe brain injury but not benefit other patients. More data are needed on how to identify treatment-responsive patients and on how to titrate the timing and duration of TTM-hypothermia.

Management of comatose survivors of out-of-hospital cardiac arrest in Europe: current treatment practice and adherence to guidelines. A joint survey by the Association for Acute CardioVascular Care (ACVC) of the ESC, the European Resuscitation Council (ERC), the European Society for Emergency Medicine (EUSEM), and the European Society of Intensive Care Medicine (ESICM)

AIMS

International guidelines give recommendations for the management of comatose out-of-hospital cardiac arrest (OHCA) survivors. We aimed to investigate adherence to guidelines and disparities in the treatment of OHCA in hospitals in Europe.

METHODS AND RESULTS

A web-based, multi-institutional, multinational survey in Europe was conducted using an electronic platform with a predefined questionnaire developed by experts in post-resuscitation care. The survey was disseminated to all members of the societies via email, social media, websites, and newsletters in June 2021. Of 252 answers received, 237 responses from different units were included and 166 (70%) were from cardiac arrest centres. First-line vasopressor used was noradrenaline in 195 (83%) and the first-line inotrope was dobutamine in 148 (64%) of the responses. Echocardiography is available 24/7 in 204 (87%) institutions. Targeted temperature management was used in 160 (75%) institutions for adult comatose survivors of OHCA with an initial shockable rhythm. Invasive or external cooling methods with feedback were used in 72 cardiac arrest centres (44%) and 17 (24%) non-cardiac arrest centres (P < 0.0003). A target temperature between 32 and 34°C was preferred by 46 centres (21%); a target between 34 and 36°C by 103 centres (52%); and <37.5°C by 35 (16%). Multimodal neuroprognostication was poorly implemented and a follow-up at 3 months after discharge was done in 71 (30%) institutions.

CONCLUSION

Post-resuscitation care is not well established and varies among centres in European hospitals. Cardiac arrest centres have a higher coherence with guidelines compared with respondents from non-cardiac arrest centres. The overall inconsistency in approaches and deviation from recommendations could be a focus for improvement.

2022 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces

This is the sixth annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. This summary addresses the most recently published resuscitation evidence reviewed by International Liaison Committee on Resuscitation Task Force science experts. Topics covered by systematic reviews include cardiopulmonary resuscitation during transport; approach to resuscitation after drowning; passive ventilation; minimizing pauses during cardiopulmonary resuscitation; temperature management after cardiac arrest; use of diagnostic point-of-care ultrasound during cardiac arrest; use of vasopressin and corticosteroids during cardiac arrest; coronary angiography after cardiac arrest; public-access defibrillation devices for children; pediatric early warning systems; maintaining normal temperature immediately after birth; suctioning of amniotic fluid at birth; tactile stimulation for resuscitation immediately after birth; use of continuous positive airway pressure for respiratory distress at term birth; respiratory and heart rate monitoring in the delivery room; supraglottic airway use in neonates; prearrest prediction of in-hospital cardiac arrest mortality; basic life support training for likely rescuers of high-risk populations; effect of resuscitation team training; blended learning for life support training; training and recertification for resuscitation instructors; and recovery position for maintenance of breathing and prevention of cardiac arrest. Members from 6 task forces have assessed, discussed, and debated the quality of the evidence using Grading of Recommendations Assessment, Development, and Evaluation criteria and generated consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence-to-Decision Framework Highlights sections, and priority knowledge gaps for future research are listed.

Recent developments and controversies in therapeutic hypothermia after cardiopulmonary resuscitation

Therapeutic hypothermia was recommended as the only neuroprotective treatment in comatose patients after return of spontaneous circulation (ROSC). With new evidence suggesting a similar neuroprotective effect of 36 °C and 33 °C, the term "therapeutic hypothermia" was substituted by "targeted temperature management" in 2011, which in turn was replaced by the term "temperature control" in 2022 because of new evidence of the similar effects of target normothermia and 33 °C. However, there is no clear consensus on the efficacy of therapeutic hypothermia. In this article, we provide an overview of the recent evidence from basic and clinical research related to therapeutic hypothermia and re-evaluate its application as a post-ROSC neuroprotective intervention in clinical settings.

Outcomes after decrease in hypothermia usage for out of Hospital Cardiac arrest after targeted temperature management study

OBJECTIVE

Evaluate trends in targeted temperature management with regards to temperature selection, its effect on neurologic outcomes at discharge, and compare this with recent large randomized controlled trial outcomes.

DESIGN

Retrospective cohort study between January 2010 and December 2019.

SETTING

Single large tertiary academic community hospital.

PATIENTS

634 adult non-traumatic patients presenting with out of hospital cardiac arrest with persistent comatose state treated with active targeted temperature management.

INTERVENTIONS, MEASUREMENTS, AND MAIN RESULTS

473 patients received hypothermia of 33 °C and were compared to 161 patients who received targeted normothermia of 36.5 °C. The primary outcome was Cerebral Performance Category (CPC) at hospital discharge, with levels 1 or 2 considered good outcomes. Mortality, ICU days, ventilator days, and overall hospital stay length were secondary outcomes. Patients receiving T33 had more favorable CPC outcomes when compared to patients receiving T36.5 (OR = 2.4 [1.3, 4.6], p = 0.006). Subgroup analysis of initial non-shockable rhythms demonstrated improved CPC scores (OR = 2.5, p = 0.04), however this was not maintained in the shockable rhythm group. T33 patients had a shorter length of stay. Mortality, ICU days, and ventilator days did not differ between the groups.

CONCLUSIONS

Out of hospital cardiac arrest patients with persistent comatose state treated with hypothermia of 33 °C had improved odds of discharge with good neurologic outcomes when compared to those treated with targeted normothermia. This improvement of outcomes appears to have been driven by the improved outcomes in the patients who had presented with non-shockable rhythm.

Feasibility of electroacupuncture at Baihui (GV20) and Zusanli (ST36) on survival with a favorable neurological outcome in patients with postcardiac arrest syndrome after in-hospital cardiac arrest: study protocol for a pilot randomized controlled trial

BACKGROUND

At present, even the first-line medication epinephrine still shows no evidence of a favourable neurological outcome in patients with sudden cardiac arrest (SCA). The high mortality of patients with postcardiac arrest syndrome (PCAS) can be attributed to brain injury, myocardial dysfunction, systemic ischaemia/reperfusion response, and persistent precipitating pathology. Targeted temperature management, the only clinically proven method in the treatment of PCAS, is still associated with a series of problems that have not been completely resolved. Acupuncture is a crucial therapy in traditional Chinese medicine. On the basis of the results of previous studies, we hypothesize that electroacupuncture (EA) might provide therapeutic benefits in the treatment of PCAS. This study will explore the feasibility of EA on SCA patients.

METHODS

This is a prospective pilot, randomized controlled clinical trial. Eligible patients with PCAS after in-hospital cardiac arrest (IHCA) admitted to our department will be randomly allocated to the control group or the EA group. Both groups will receive standard therapy according to American Heart Association guidelines for cardiopulmonary resuscitation. However, the EA group will also receive acupuncture at the Baihui acupoint (GV20) and Zusanli acupoint (ST36) with EA stimulation for 30 min using a dense-dispersed wave at frequencies of 20 and 100 Hz, a current intensity of less than 10 mA, and a pulse width of 0.5 ms. EA treatment will be administered for up to 14 days (until either discharge or death). The primary endpoint is survival with a favourable neurological outcome. The secondary endpoints are neurological scores, cardiac function parameters, and other clinical parameters, including Sequential Organ Failure Assessment (SOFA) scores and Acute Physiology and Chronic Health Evaluation (APACHE) II scores, on days 0 to 28.

DISCUSSION

This study will provide crucial clinical evidence on the efficacy of EA in PCAS when used as an adjunctive treatment with AHA standard therapy.

TRIAL REGISTRATION

chictr.org.cn : ChiCTR2000040040. Registered on 19 November 2020. Retrospectively registered. http://www.chictr.org.cn/ .

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.

2022 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces

This is the sixth annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. This summary addresses the most recently published resuscitation evidence reviewed by International Liaison Committee on Resuscitation Task Force science experts. Topics covered by systematic reviews include cardiopulmonary resuscitation during transport; approach to resuscitation after drowning; passive ventilation; minimizing pauses during cardiopulmonary resuscitation; temperature management after cardiac arrest; use of diagnostic point-of-care ultrasound during cardiac arrest; use of vasopressin and corticosteroids during cardiac arrest; coronary angiography after cardiac arrest; public-access defibrillation devices for children; pediatric early warning systems; maintaining normal temperature immediately after birth; suctioning of amniotic fluid at birth; tactile stimulation for resuscitation immediately after birth; use of continuous positive airway pressure for respiratory distress at term birth; respiratory and heart rate monitoring in the delivery room; supraglottic airway use in neonates; prearrest prediction of in-hospital cardiac arrest mortality; basic life support training for likely rescuers of high-risk populations; effect of resuscitation team training; blended learning for life support training; training and recertification for resuscitation instructors; and recovery position for maintenance of breathing and prevention of cardiac arrest. Members from 6 task forces have assessed, discussed, and debated the quality of the evidence using Grading of Recommendations Assessment, Development, and Evaluation criteria and generated consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence-to-Decision Framework Highlights sections, and priority knowledge gaps for future research are listed.

2022 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces

This is the sixth annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. This summary addresses the most recently published resuscitation evidence reviewed by International Liaison Committee on Resuscitation Task Force science experts. Topics covered by systematic reviews include cardiopulmonary resuscitation during transport; approach to resuscitation after drowning; passive ventilation; minimising pauses during cardiopulmonary resuscitation; temperature management after cardiac arrest; use of diagnostic point-of-care ultrasound during cardiac arrest; use of vasopressin and corticosteroids during cardiac arrest; coronary angiography after cardiac arrest; public-access defibrillation devices for children; pediatric early warning systems; maintaining normal temperature immediately after birth; suctioning of amniotic fluid at birth; tactile stimulation for resuscitation immediately after birth; use of continuous positive airway pressure for respiratory distress at term birth; respiratory and heart rate monitoring in the delivery room; supraglottic airway use in neonates; prearrest prediction of in-hospital cardiac arrest mortality; basic life support training for likely rescuers of high-risk populations; effect of resuscitation team training; blended learning for life support training; training and recertification for resuscitation instructors; and recovery position for maintenance of breathing and prevention of cardiac arrest. Members from 6 task forces have assessed, discussed, and debated the quality of the evidence using Grading of Recommendations Assessment, Development, and Evaluation criteria and generated consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence-to-Decision Framework Highlights sections, and priority knowledge gaps for future research are listed.

The Effects of Temperature Management on Brain Microcirculation, Oxygenation and Metabolism

Purpose: Target temperature management (TTM) is often used in patients after cardiac arrest, but the effects of cooling on cerebral microcirculation, oxygenation and metabolism are poorly understood. We studied the time course of these variables in a healthy swine model.Methods: Fifteen invasively monitored, mechanically ventilated pigs were allocated to sham procedure (normothermia, NT; n = 5), cooling (hypothermia, HT, n = 5) or cooling with controlled oxygenation (HT-Oxy, n = 5). Cooling was induced by cold intravenous saline infusion, ice packs and nasal cooling to achieve a body temperature of 33–35 °C. After 6 h, animals were rewarmed to baseline temperature (within 5 h). The cerebral microvascular network was evaluated (at baseline and 2, 7 and 12 h thereafter) using sidestream dark-field (SDF) video-microscopy. Cerebral blood flow (laser Doppler MNP100XP, Oxyflow, Oxford Optronix, Oxford, UK), oxygenation (PbtO₂, Licox catheter, Integra Lifesciences, USA) and lactate/pyruvate ratio (LPR) using brain microdialysis (CMA, Stockholm, Sweden) were measured hourly. Results: In HT animals, cerebral functional capillary density (FCD) and proportion of small-perfused vessels (PSPV) significantly decreased over time during the cooling phase; concomitantly, PbtO₂ increased and LPR decreased. After rewarming, all microcirculatory variables returned to normal values, except LPR, which increased during the rewarming phase in the two groups subjected to HT when compared to the group maintained at normothermia. Conclusions: In healthy animals, TTM can be associated with alterations in cerebral microcirculation during cooling and altered metabolism at rewarming.

Through the Looking Glass: The Paradoxical Evolution of Targeted Temperature Management for Comatose Survivors of Cardiac Arrest

For the past two decades, targeted temperature management (TTM) has been a staple in the care of comatose survivors following cardiac arrest. However, recent clinical trials have failed to replicate the benefit seen in earlier studies, bringing into question the very existence of such clinical practice. In this review, we explore clinical scenarios within critical care that appeared to share a similar fate, but in actuality changed the landscape of practice in a modern world. Accordingly, clinicians may apply these lessons to the utilization of TTM among comatose survivors following cardiac arrest, potentially paving way for a re-framing of clinical care amidst an environment where current data appears upside down in comparison to past successes.

[ERC-ESICM guidelines on temperature control after cardiac arrest]

Die Leitlinien des European Resuscitation Council (ERC), die 2021 veröffentlicht wurden, empfehlen eine aktive Temperaturkontrolle zwischen 32 und 36 °C für alle erwachsenen Patient:innen, die nach Wiedererlangen des Spontankreislaufs nach prä- oder innerklinischer Reanimation das Bewusstsein nicht wiedererlangen.

Wenige Wochen nach Veröffentlichung der Leitlinien 2021 wurde die TTM2-Studie publiziert, in der kein signifikanter Unterschied im Hinblick auf das Überleben oder das funktionelle Outcome nach sechs Monaten zwischen einer Zieltemperatur von 33 °C und einer Fiebervermeidung nach außerklinischem Herz-Kreislauf-Stillstand festgestellt worden war.

Als Antwort auf die zusätzliche Evidenz durch die TTM2-Studie nahm die Advanced Life Support Task Force des International Liaison Committee on Resuscitation (ILCOR) eine Reevaluation der aktuellen Datenlage vor, die in einer überarbeiteten Empfehlung zur Temperaturkontrolle nach Herz-Kreislauf-Stillstand bei Erwachsenen resultierte. Der aktuelle Artikel fasst die aktualisierten Leitlinien zusammen und diskutiert kritische Aspekte der neuen Empfehlungen.

Target temperature management versus normothermia without temperature feedback systems for out-of-hospital cardiac arrest survivors

OBJECTIVE

The clinical benefit of automatic temperature control devices remains unclear. We investigated the outcomes of out-of-hospital cardiac arrest (OHCA) survivors who had undergone either target temperature management (TTM) with a temperature feedback system (TFS) or maintenance of normothermia without a TFS during post-resuscitation care.

METHODS

This study was a retrospective analysis of a multicenter prospective cohort of OHCA survivors who had received postcardiac arrest care from August 2014 to December 2018. The overlap propensity score weighting method was applied for adjustment between groups.

RESULTS

A total of 405 OHCA survivors were included. TTM with a TFS and normothermia without a TFS were applied to 318 and 87 patients, respectively. Fever events were more common in patients with normothermia without a TFS. After propensity score matching, no statistically significant differences were observed in the 1-month good neurologic outcome (odds ratio 0.99, 95% confidence interval [CI] 0.56-1.25) or survival rate (odds ratio 1.25, 95% CI 0.88-1.78).

CONCLUSION

No significant differences in the 1-month neurologic outcome were observed between patients receiving TTM with a TFS and those undergoing normothermia without a TFS.

The association of different target temperatures in targeted temperature management with neurological outcome after out-of-hospital cardiac arrest based on a prospective multicenter observational study in Korea (the KORHN-PRO registry): IPTW analysis

Background

Among comatose survivors of out-of-hospital cardiac arrest (OHCA), targeted temperature management (TTM) has improved neurological outcomes. However, although the target temperature shifted from 33°C to 33°C~36°C, the optimal target temperature is still unclear. The goal of this study was to evaluate neurological outcomes at 6 months at target temperatures of 33°C and 36°C.

Materials and methods

We analyzed OHCA survivors who underwent TTM and were recorded in the Korean Hypothermia Network, a prospective multicenter registry, from October 2015 to December 2018. The primary outcome was good neurological outcome at six months, defined as a cerebral performance category of 1–2, and the secondary outcome was survival at 6 months.

Results

A total of 1339 patients were treated with TTM in twenty-two emergency departments. Of those, 1054 were treated at 33°C, and 285 were treated at 36°C. There was no significant difference in good neurological outcomes at 6 months (30.6% vs. 31.2%, p = 0.850, adjusted OR 0.97, 95% CI = 0.73–1.29]) and survival at six months (41.4% vs. 38.7%, p = 0.401, adjusted HR 1.08, 95% CI = 0.91–1.28]) between TTM 33°C and TTM 36°C. After propensity score matching, good neurological outcomes at 6 months (OR 0.93, 95% CI = 0.74–1.18) and survival at 6 months (HR 1.05, 95% CI = 0.92–1.21) were still not associated with TTM 33°C and TTM 36°C.

Conclusion

In this study, patients treated with a target temperature of 33°C had similar good neurological outcomes and survival at six months compared with those treated with a target temperature of 36°C.

Targeted temperature management after out of hospital cardiac arrest: quo vadis?

Targeted temperature management (TTM) has become a cornerstone in the treatment of comatose post-cardiac arrest patients over the last two decades. Belief in the efficacy of this intervention for improving neurologically intact survival was based on two trials from 2002, one truly randomized-controlled and one small quasi-randomized trial, without clear confirmation of that finding. Subsequent large randomized trials reported no difference in outcomes between TTM at 33 vs. 36°C and no benefit of TTM at 33°C as compared with fever control alone. Given that these results may help shape post-cardiac arrest patient care, we sought to review the history and rationale as well as trial evidence for TTM, critically review the TTM2 trial, and highlight gaps in knowledge and research needs for the future. Finally, we provide contemporary guidance for the use of TTM in daily clinical practice.

Intravascular Versus Surface Cooling in Patients Resuscitated From Cardiac Arrest: A Systematic Review and Network Meta-Analysis With Focus on Temperature Feedback

OBJECTIVE

The aim of the study was to compare the effect of intravascular cooling (IC), surface cooling with temperature feedback (SCF), and surface cooling without temperature feedback (SCnoF) on neurologic outcome and survival in patients successfully resuscitated from cardiac arrest (CA) and treated with targeted temperature management (TTM) at 32-34°C.

DATA SOURCES

We performed a systematic review on Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, MEDLINE, SCOPUS, CINAHL, Web of Science, and Clinical Trials up to June 30, 2021.

STUDY SELECTION

We included randomized and nonrandomized studies on IC, SCF, and SCnoF in adult humans resuscitated from CA undergoing TTM, reporting neurologic outcome or survival.

DATA EXTRACTION

We performed a network meta-analysis to assess the comparative effects of IC, SCF, and SCnoF. The overall effect between two cooling methods included the effect of direct and indirect comparisons. Results are given as odds ratios (OR) and 95% CIs. Rankograms estimated the probability of TTM methods being ranked first, second, and third best interventions.

DATA SYNTHESIS

A total of 14 studies involving 4,062 patients met the inclusion criteria. Four studies were randomized controlled studies, and 10 studies were nonrandomized observational studies. IC compared with SCnoF was significantly associated with better neurologic outcome (OR, 0.6; 95% CI, 0.49-0.74) and survival (OR, 0.8; 95% CI, 0.66-0.96). IC compared with SCF, and SCF compared with SCnoF did not show significant differences in neurologic outcome and survival. The rankogram showed that IC had the highest probability to be the most beneficial cooling method, followed by SCF and SCnoF.

CONCLUSIONS

Our results suggest that in patients resuscitated from CA and treated with TTM at 32-34°C, IC has the highest probability of being the most beneficial cooling method for survival and neurologic outcome.

Simulation-based assessment of trainee's performance in post-cardiac arrest resuscitation

Objectives

To assess trainees’ performance in managing a patient with post-cardiac arrest complicated by status epilepticus.

Methods

In this prospective, observational, single-center simulation-based study, trainees ranging from sub interns to critical care fellows evaluated and managed a post cardiac arrest patient, complicated by status epilepticus. Critical action items were developed by a modified Delphi approach based on American Heart Association guidelines and the Neurocritical Care Society’s Emergency Neurological Life Support protocols. The primary outcome measure was the critical action item sum score. We sought validity evidence to support our findings by including attending neurocritical care physicians and comparing performance across four levels of training.

Results

Forty-nine participants completed the simulation. The mean sum of critical actions completed by trainees was 10/21 (49%). Eleven (22%) trainees verbalized a differential diagnosis for the arrest. Thirty-two (65%) reviewed the electrocardiogram, recognized it as abnormal, and consulted cardiology. Forty trainees (81%) independently decided to start temperature management, but only 20 (41%) insisted on it when asked to reconsider. There was an effect of level of training on critical action checklist sum scores (novice mean score [standard deviation (SD)] = 4.8(1.8) vs. intermediate mean score (SD) = 10.4(2.1) vs. advanced mean score (D) = 11.6(3.0) vs. expert mean score (SD) = 14.7(2.2))

Conclusions

High-fidelity manikin-based simulation holds promise as an assessment tool in the performance of post-cardiac arrest care.

Contemporary targeted temperature management: Clinical evidence and controversies

Advancements in cardiac arrest and post-cardiac arrest care have led to improved survival to hospital discharge. While survival to hospital discharge is an important clinical outcome, neurologic recovery is also a priority. With the advancement of targeted temperature management (TTM), the American Heart Association guidelines for post-cardiac arrest care recommend TTM in patients who remain comatose after return of spontaneous circulation (ROSC). Recently, the TTM2 randomized controlled trial found no significant difference in neurologic function and mortality at 6-months between traditional hypothermia to 33°C versus 37.5°C. While TTM has been evaluated for decades, current literature suggests that the use of TTM to 33° when compared to a protocol of targeted normothermia does not result in improved outcomes. Instead, perhaps active avoidance of fever may be most beneficial. Extracorporeal cardiopulmonary resuscitation and membrane oxygenation can provide a means of both hemodynamic support and TTM after ROSC. This review aims to describe the pathophysiology, physiologic aspects, clinical trial evidence, changes in post-cardiac arrest care, potential risks, as well as controversies of TTM.

Temperature Management in the ICU

OBJECTIVE

Temperature abnormalities are recognized as a marker of human disease, and the therapeutic value of temperature is an attractive treatment target. The objective of this synthetic review is to summarize and critically appraise evidence for active temperature management in critically ill patients.

DATA SOURCES

We searched MEDLINE for publications relevant to body temperature management (including targeted temperature management and antipyretic therapy) in cardiac arrest, acute ischemic and hemorrhagic stroke, traumatic brain injury, and sepsis. Bibliographies of included articles were also searched to identify additional relevant studies.

STUDY SELECTION

English-language systematic reviews, meta-analyses, randomized trials, observational studies, and nonhuman data were reviewed, with a focus on the most recent randomized control trial evidence.

DATA EXTRACTION

Data regarding study methodology, patient population, temperature management strategy, and clinical outcomes were qualitatively assessed.

DATA SYNTHESIS

Temperature management is common in critically ill patients, and multiple large trials have been conducted to elucidate temperature targets, management strategies, and timing. The strongest data concerning the use of therapeutic hypothermia exist in comatose survivors of cardiac arrest, and recent trials suggest that appropriate postarrest temperature targets between 33°C and 37.5°C are reasonable. Targeted temperature management in other critical illnesses, including acute stroke, traumatic brain injury, and sepsis, has not shown benefit in large clinical trials. Likewise, trials of pharmacologic antipyretic therapy have not demonstrated improved outcomes, although national guidelines do recommend treatment of fever in patients with stroke and traumatic brain injury based on observational evidence associating fever with worse outcomes.

CONCLUSIONS

Body temperature management in critically ill patients remains an appealing therapy for several illnesses, and additional studies are needed to clarify management strategies and therapeutic pathways.

Effects of Different Hypothermia on the Results of Cardiopulmonary Resuscitation in a Cardiac Arrest Rat Model

Objective

To investigate the optimal temperature of hypothermia treatment in rats with cardiac arrest caused by ventricular fibrillation (VF) after the return of spontaneous circulation (ROSC).

Methods

A total of forty-eight male Sprague-Dawley rats were induced by VF through the guidewire with a maximum of 5 mA current and untreated for 8 min. Cardiopulmonary resuscitation (CPR) was performed for 8 min followed by defibrillation (DF). Resuscitated rats were then randomized into the normothermia (37°C) group, milder (35°C) group, mild (33°C) group, or moderate (28°C) group. Hypothermia was immediately induced with surface cooling. The target temperature was maintained for 4 h before rewarming to 37 ± 0.5°C. Moreover, at the end of the 4 h, a rat in each group was randomly selected to be sacrificed for the cerebral cortex electron microscopy observation (n = 1). The other resuscitated animals were observed for up to 72 h after ROSC (n = 7). Left ventricular ejection fraction (LVEF) and left ventricular end diastolic volume (LVEDV) were measured. Survival time, survival rate, and neurological deficit score (NDS) were recorded for 72 h.

Results

During hypothermia, higher LVEF was observed in the hypothermia groups when compared with normothermia group (35°C vs. 37°C, p < 0.05, 33°C and 28°C vs. 37°C, p < 0.01). Among the hypothermia groups, LVEF was higher in the 28°C group than that of 35°C (p < 0.05). However, both the heart rate (HR) (p < 0.01) and LVEDV (28°C vs. 35°C, p < 0.01, 28°C vs. 37°C and 33°C, p < 0.05) were lowest in the 28°C group when compared with the other groups. There were no significant differences of LVEF and LVEDV between the group 35°C and 33°C (p > 0.05). After rewarming, the LVEF of 35°C group was higher than that of group 37°C, 33°C, and 28°C (35°C vs. 37°C and 28°C, p < 0.01, 35°C vs. 33°C, p < 0.05). Group 35°C and 33°C resulted in longer survival (p < 0.01), higher survival rate (p < 0.01), and lower NDS (35°C vs. 37°C and 28°C, p < 0.01, 33°C vs. 37°C and 28°C, p < 0.05) compared with the group 37°C and 28°C. The extent of damage to cerebral cortex cells in group of 35°C and 33°C was lighter than that in group of 37°C and 28°C. The 35°C group spent less time in the process of cooling and rewarming than the group 33°C and 28°C (p < 0.01).

Conclusions

An almost equal protective effect of milder hypothermia (35°C) and mild hypothermia (33°C) in cardiac arrest (CA) rats was achieved with more predominant effect than moderate hypothermia (28°C) and normothermia (37°C). More importantly, shorter time spent in cooling and rewarming was required in the 35°C group, indicating its potential clinical application. These findings support the possible use of milder hypothermia (35°C) as a therapeutic agent for postresuscitation.

Clinical Outcomes with Targeted Temperature Management (TTM) in Comatose Out-of-Hospital Cardiac Arrest Patients-A Retrospective Cohort Study

Purpose: we evaluated the effects of the shift of a targeted temperature management (TTM) strategy from 33 °C to 36 °C in comatose out-of-hospital cardiac arrest (OHCA) patients admitted to the Intensive Care Unit (ICU). Methods: we performed a retrospective study of all comatose (GCS < 8) OHCA patients treated with TTM from 2010 to 2018 (n = 798) from a single-center academic hospital. We analyzed 90-day mortality, and neurological outcome (CPC score) at ICU discharge and ICU length of stay, as primary and secondary outcomes, respectively. Results: we included 798 OHCA patients (583 in the TTM33 group and 215 in the TTM36 group). We found no association between the TTM strategy (TTM33 and TTM36) and 90-day mortality (hazard ratio (HR)] 0.877, 95% CI 0.677−1.135, with TTM36 as reference). Also, no association was found between TTM strategy and favorable neurological outcome at ICU discharge (odds ratio (OR) 1.330, 95% CI 0.941−1.879). Patients in the TTM33 group had on average a longer ICU LOS (beta 1.180, 95% CI 0.222−2.138). Conclusion: no differences in clinical outcomes—both 90-day mortality and favorable neurological outcome at ICU discharge—were found between targeted temperature at 33 °C and 36 °C. These results may help to corroborate previous trial findings and assist in implementation of TTM.

ERC-ESICM guidelines on temperature control after cardiac arrest in adults

The aim of these guidelines is to provide evidence‑based guidance for temperature control in adults who are comatose after resuscitation from either in-hospital or out-of-hospital cardiac arrest, regardless of the underlying cardiac rhythm. These guidelines replace the recommendations on temperature management after cardiac arrest included in the 2021 post-resuscitation care guidelines co-issued by the European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM). The guideline panel included thirteen international clinical experts who authored the 2021 ERC-ESICM guidelines and two methodologists who participated in the evidence review completed on behalf of the International Liaison Committee on Resuscitation (ILCOR) of whom ERC is a member society. We followed the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to assess the certainty of evidence and grade recommendations. The panel provided suggestions on guideline implementation and identified priorities for future research. The certainty of evidence ranged from moderate to low. In patients who remain comatose after cardiac arrest, we recommend continuous monitoring of core temperature and actively preventing fever (defined as a temperature > 37.7 °C) for at least 72 hours. There was insufficient evidence to recommend for or against temperature control at 32-36 °C or early cooling after cardiac arrest. We recommend not actively rewarming comatose patients with mild hypothermia after return of spontaneous circulation (ROSC) to achieve normothermia. We recommend not using prehospital cooling with rapid infusion of large volumes of cold intravenous fluids immediately after ROSC.

ERC-ESICM guidelines on temperature control after cardiac arrest in adults

The aim of these guidelines is to provide evidence‑based guidance for temperature control in adults who are comatose after resuscitation from either in-hospital or out-of-hospital cardiac arrest, regardless of the underlying cardiac rhythm. These guidelines replace the recommendations on temperature management after cardiac arrest included in the 2021 post-resuscitation care guidelines co-issued by the European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM). The guideline panel included thirteen international clinical experts who authored the 2021 ERC-ESICM guidelines and two methodologists who participated in the evidence review completed on behalf of the International Liaison Committee on Resuscitation (ILCOR) of whom ERC is a member society. We followed the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to assess the certainty of evidence and grade recommendations. The panel provided suggestions on guideline implementation and identified priorities for future research. The certainty of evidence ranged from moderate to low. In patients who remain comatose after cardiac arrest, we recommend continuous monitoring of core temperature and actively preventing fever (defined as a temperature > 37.7 °C) for at least 72 h. There was insufficient evidence to recommend for or against temperature control at 32-36 °C or early cooling after cardiac arrest. We recommend not actively rewarming comatose patients with mild hypothermia after return of spontaneous circulation (ROSC) to achieve normothermia. We recommend not using prehospital cooling with rapid infusion of large volumes of cold intravenous fluids immediately after ROSC.

The epidemiology of out-of-hospital cardiac arrest in Australia and New Zealand: A binational report from the Australasian Resuscitation Outcomes Consortium (Aus-ROC)

INTRODUCTION

The Australasian Resuscitation Outcomes Consortium (Aus-ROC) out-of-hospital cardiac arrest (OHCA) Epistry (Epidemiological Registry) now covers 100% of Australia and New Zealand (NZ). This study reports and compares the Utstein demographics, arrest characteristics and outcomes of OHCA patients across our region.

METHODS

We included all OHCA cases throughout 2019 as submitted to the Epistry by the eight Australian and two NZ emergency medical services (EMS). We calculated crude and age-standardised incidence rates and performed a national and EMS regional comparison.

RESULTS

We obtained data for 31,778 OHCA cases for 2019: 26,637 in Australia and 5,141 in NZ. Crude incidence was 107.9 per 100,000 person-years in Australia and 103.2/100,000 in NZ. Overall, the majority of OHCAs occurred in adults (96%), males (66%), private residences (76%), were unwitnessed (63%), of presumed medical aetiology (83%), and had an initial monitored rhythm of asystole (64%). In non-EMS-witnessed cases, 38% received bystander CPR and 2% received public defibrillation. Wide variation was seen between EMS regions for all OHCA demographics, arrest characteristics and outcomes. In patients who received an EMS-attempted resuscitation (13,664/31,778): 28% (range across EMS=13.1% to 36.7%) had return of spontaneous circulation (ROSC) at hospital arrival and 13% (range across EMS=9.9% to 20.7%) survived to hospital discharge/30-days. Survival in the Utstein comparator group (bystander-witnessed in shockable rhythm) varied across the EMS regions between 27.4% to 42.0%.

CONCLUSION

OHCA across Australia and NZ has varied incidence, characteristics and survival. Understanding the variation in survival and modifiable predictors is key to informing strategies to improve outcomes.