Systematic review and meta-analysis of intravascular temperature management vs. surface cooling in comatose patients resuscitated from cardiac arrest

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.

TREATMENT OF COMATOSE SURVIVORS OF IN-HOSPITAL CARDIAC ARREST WITH EXTENDED ENDOVASCULAR COOLING METHOD FOR 72 H: A PROPENSITY SCORE-MATCHED ANALYSIS

ABSTRACT

Aims: Targeted temperature management is recommended for at least 24 h in comatose survivors of in-hospital cardiac arrest (IHCA) after the return of spontaneous circulation; however, whether an extension for 72 h leads to better neurological outcomes is uncertain. Methods: We included data from the Qilu Hospital of Shandong University between July 20, 2019, and June 30, 2022. Unconscious patients who had return of spontaneous circulation lasting >20 consecutive min and received endovascular cooling (72 h) or normothermia treatment were compared in terms of survival-to-discharge and favorable neurological survival. Propensity score matching was used to formulate balanced 1:3 matched patients. Results: In total, 2,084 patients were included. Sixteen patients received extended endovascular cooling and 48 matched controls received normothermia therapy. Compared with the normothermia group, patients who received prolonged endovascular cooling had a higher survival-to-discharge rate. However, good neurological outcomes did not differ significantly. Before matching, Cox regression analysis, using mortality as the event, showed that extended endovascular cooling independently affected the survival of IHCA patients. Conclusions: Among comatose patients who had been resuscitated from IHCA, the use of endovascular cooling for 72 h might confer a benefit on survival-to-discharge.

A Commentary on the Effect of Targeted Temperature Management in Patients Resuscitated from Cardiac Arrest

The members of the International Liaison Committee on Resuscitation (ILCOR) Advanced Life Support Task Force have written a comprehensive summary of trials of the effectiveness of induced hypothermia (IH) or targeted temperature management (TTM) in comatose patients after cardiac arrest (CA). However, in-depth analysis of these studies is incomplete, especially since there was no significant difference in primary outcome between hypothermia versus normothermia in the recently reported TTM2 trial. We critically appraise trials of IH/TTM versus normothermia to characterize reasons for the lack of treatment effect, based on a previously published framework for what to consider when the primary outcome fails. We found a strong biologic rationale and external clinical evidence that IH treatment is beneficial. Recent TTM trials mainly included unselected patients with a high rate of bystander cardiopulmonary resuscitation. The treatment was not applied as intended, which led to a large delay in achievement of target temperature. While receiving intensive care, sedative drugs were likely used that might have led to increased neurologic damage as were antiplatelet drugs that could be associated with increased acute stent thrombosis in hypothermic patients. It is reasonable to still use or evaluate IH treatment in patients who are comatose after CA as there are multiple plausible reasons why IH compared to normothermia did not significantly improve neurologic outcome in the TTM trials.

Therapeutic hypothermia in patients after cardiac arrest: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

Targeted temperature management (TTM) with therapeutic hypothermia (TH) has been used to improve neurological outcomes in patients after cardiac arrest; however, several trials have reported conflicting results regarding its effectiveness. This systematic review and meta-analysis assessed whether TH was associated with better survival and neurological outcomes after cardiac arrest.

METHOD

We searched online databases for relevant studies published before May 2023. Randomized controlled trials (RCTs) comparing TH and normothermia in post-cardiac-arrest patients were selected. Neurological outcomes and all-cause mortality were assessed as the primary and secondary outcomes, respectively. A subgroup analysis according to initial electrocardiography (ECG) rhythm was performed.

RESULT

Nine RCTs (4058 patients) were included. The neurological prognosis was significantly better in patients with an initial shockable rhythm after cardiac arrest (RR = 0.87, 95% confidence interval [CI] = 0.76-0.99, P = 0.04), especially in those with earlier TH initiation (<120 min) and prolonged TH duration (≥24 h). However, the mortality rate after TH was not lower than that after normothermia (RR = 0.91, 95% CI = 0.79-1.05). In patients with an initial nonshockable rhythm, TH did not provide significantly more neurological or survival benefits (RR = 0.98, 95% CI = 0.93-1.03 and RR = 1.00, 95% CI = 0.95-1.05, respectively).

CONCLUSION

Current evidence with a moderate level of certainty suggests that TH has potential neurological benefits for patients with an initial shockable rhythm after cardiac arrest, especially in those with faster TH initiation and longer TH maintenance.

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.

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; 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.

Cost-Effectiveness Analysis of Intravascular Targeted Temperature Management after Cardiac Arrest in England

BACKGROUND

Targeted temperature management (TTM) has been shown to improve neurological outcomes and survival in patients resuscitated from cardiac arrest; however, the cost effectiveness of multiple TTM methods is not well studied.

OBJECTIVE

This study aimed to evaluate the cost effectiveness of intravascular temperature management (IVTM) using Thermogard XP compared with surface cooling methods after cardiac arrest in the England from the perspectives of the UK national health service and Personal Social Services.

METHODS

We developed a multi-state Markov model that evaluated IVTM (Thermogard XP) compared with surface cooling using two different devices (Blanketrol III and Arctic Sun 5000) over a short-term and lifetime time horizon. Model input parameters were obtained from the literature and local databases. We assumed a hypothetical cohort of 1000 patients who required TTM after cardiac arrest per year in the England. The outcomes were costs (in £, year 2019 values) and quality-adjusted life-years (QALYs), discounted at 3.5% annually. Deterministic and probabilistic sensitivity analyses were undertaken to examine the effect of alternative assumptions and uncertainty in model parameters on the results.

RESULTS

The cost-effectiveness analysis determined that Thermogard XP resulted in direct cost savings of £2339 and £2925 (per patient) compared with Blanketrol III and Arctic Sun 5000, respectively, and a gain of 0.98 QALYs over the patient lifetime. The probabilistic sensitivity analysis demonstrated that the probability of Thermogard XP being cost saving would be 69.2% and 65.3% versus the Arctic Sun 5000 and Blanketrol III, respectively.

CONCLUSION

Implementation of IVTM using Thermogard XP can lead to cost savings and improved patient quality of life versus surface cooling methods.

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.

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.

Artificial neural network-boosted Cardiac Arrest Survival Post-Resuscitation In-hospital (CASPRI) score accurately predicts outcome in cardiac arrest patients treated with targeted temperature management

Existing prognostic models to predict the neurological recovery in patients with cardiac arrest receiving targeted temperature management (TTM) either exhibit moderate accuracy or are too complicated for clinical application. This necessitates the development of a simple and generalizable prediction model to inform clinical decision-making for patients receiving TTM. The present study explores the predictive validity of the Cardiac Arrest Survival Post-resuscitation In-hospital (CASPRI) score in cardiac arrest patients receiving TTM, regardless of cardiac event location, and uses artificial neural network (ANN) algorithms to boost the prediction performance. This retrospective observational study evaluated the prognostic relevance of the CASPRI score and applied ANN to develop outcome prediction models in a cohort of 570 patients with cardiac arrest and treated with TTM between 2014 and 2019 in a nationwide multicenter registry in Taiwan. In univariate logistic regression analysis, the CASPRI score was significantly associated with neurological outcome, with the area under the receiver operating characteristics curve (AUC) of 0.811. The generated ANN model, based on 10 items of the CASPRI score, achieved a training AUC of 0.976 and validation AUC of 0.921, with the accuracy, precision, sensitivity, and specificity of 89.2%, 91.6%, 87.6%, and 91.2%, respectively, for the validation set. CASPRI score has prognostic relevance in patients who received TTM after cardiac arrest. The generated ANN-boosted, CASPRI-based model exhibited good performance for predicting TTM neurological outcome, thus, we propose its clinical application to improve outcome prediction, facilitate decision-making, and formulate individualized therapeutic plans for patients receiving TTM.

[Targeted temperature management after cardiac arrest : What is new?]

The current guidelines of the European Resuscitation Council recommend targeted temperature management to improve functional neurological outcome in comatose survivors after cardiac arrest. With the pathophysiological background of hypothermia-induced neuroprotection for prevention of hypoxic-ischemic encephalopathy, targeted temperature management is a key measure and represents a central aspect in postresuscitation care.In the 2021 guidelines the application of targeted temperature management in postresuscitation care has been recommended for all rhythms and irrespective of the location of cardiac arrest. Targeted temperature management is advocated for adult patients who remain unresponsive following return of spontaneous circulation (ROSC) after either out-of-hospital cardiac arrest or in-hospital cardiac arrest. The body temperature should be maintained at a constant value between 32 °C and 36 °C for at least 24 h. To avoid rebound hyperthermia, fever following targeted temperature management, defined as a temperature above 37.7 °C, should be prevented and treated for at least 72 h after ROSC in persistently comatose patients. The routine use of prehospital cooling by rapid infusion of large volumes of cold i.v. fluid immediately after ROSC is not recommended.Based on a systematic review of the current literature, this article summarizes the results of randomized trials and new findings on targeted temperature management in comatose adult patients after cardiac arrest. The review has a particular focus on the most recent evidence regarding the optimum range of target temperatures. Furthermore, recent data on preclinical management, different patient populations, the duration of targeted temperature management, cooling methods and rebound hyperthermia are discussed.The impact of targeted temperature management on neurological outcome after cardiac arrest has been a matter of controversy. Despite contradictory results and heterogeneity of study designs, the current evidence supports the relevance and the necessity of strict temperature control in postresuscitation care for neuroprotection and improvement in functional neurological outcomes.

Impact of cooling method on the outcome of initial shockable or non-shockable out of hospital cardiac arrest patients receiving target temperature management: a nationwide multicentre cohort study

Background

Little is known about the effectiveness of surface cooling (SC) and endovascular cooling (EC) on the outcome of out-of-hospital cardiac arrest (OHCA) patients receiving target temperature management (TTM) according to their initial rhythm.

Methods

We retrospectively analysed data from the Japanese Association for Acute Medicine Out‐of‐Hospital Cardiac Arrest registry, a multicentre, prospective nationwide database in Japan. For our analysis, OHCA patients aged ≥ 18 years who were treated with TTM between June 2014 and December 2017 were included. The primary outcome was 30-day survival with favourable neurological outcome defined as a Glasgow–Pittsburgh cerebral performance category score of 1 or 2. Cooling methods were divided into the following groups: SC (ice packs, fans, air blankets, and surface gel pads) and EC (endovascular catheters and any dialysis technique). We investigated the efficacy of the two categories of cooling methods in two different patient groups divided according to their initially documented rhythm at the scene (shockable or non-shockable) using multivariable logistic regression analysis and propensity score analysis with inverse probability weighting (IPW).

Results

In the final analysis, 1082 patients were included. Of these, 513 (47.4%) had an initial shockable rhythm and 569 (52.6%) had an initial non-shockable rhythm. The proportion of patients with favourable neurological outcomes in SC and EC was 59.9% vs. 58.3% (264/441 vs. 42/72), and 11.8% (58/490) vs. 21.5% (17/79) in the initial shockable patients and the initial non-shockable patients, respectively. In the multivariable logistic regression analysis, differences between the two cooling methods were not observed among the initial shockable patients (adjusted odd ratio [AOR] 1.51, 95% CI 0.76–3.03), while EC was associated with better neurological outcome among the initial non-shockable patients (AOR 2.21, 95% CI 1.19–4.11). This association was constant in propensity score analysis with IPW (OR 1.40, 95% CI 0.83–2.36; OR 1.87, 95% CI 1.01–3.47 among the initial shockable and non-shockable patients, respectively).

Conclusion

We suggested that the use of EC was associated with better neurological outcomes in OHCA patients with initial non-shockable rhythm, but not in those with initial shockable rhythm. A TTM implementation strategy based on initial rhythm may be important.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00953-y.

Comparison of hydrogel pad and water-circulating blanket cooling methods for targeted temperature management: A propensity score-matched analysis from a prospective multicentre registry

BACKGROUND

Various methods have been used to control body temperature in targeted temperature management (TTM), but few studies have compared specific subtypes of surface cooling systems. The aim of this study was to compare the efficiencies and neurological outcomes between hydrogels pad and water-circulating blanket cooling methods.

METHODS

We conducted a multicentre, prospective, registry-based study of out-of-hospital cardiac arrest patients treated with TTM between 2015 and 2018. We compared the neurological outcomes, efficacies for cooling, and adverse events between patients who received TTM using a hydrogel pad and water-circulating blanket cooling. Patients were one-to-one matched using propensity scores to adjust for differences in the baseline characteristics of each cooling method. The primary outcome was a favourable neurological outcome at 6 months.

RESULTS

We included 1,132 patients in the analysis, 870 of whom underwent hydrogel pad cooling, and the remaining 262 underwent water-circulating blanket cooling. In the unmatched cohort, a greater number of adverse events occurred in the water-circulating blanket group. The favourable neurologic outcome rates at 6 months were similar between the hydrogel pad group and the water circulating blanket group (30.2% vs. 29.8%, p = 0.939). In the propensity-matched cohort, which included 184 pairs, the rates of adverse events between the two groups were similar. The similarity of favourable neurologic outcome rates at 6 months between the two groups persisted (28.8% vs. 29.9%, p = 0.819).

CONCLUSION

Neurological outcomes and adverse events between the hydrogel pad cooling and water-circulating blanket cooling groups were similar.

Targeted temperature management in adult cardiac arrest: Systematic review and meta-analysis

AIM

To perform a systematic review and meta-analysis on targeted temperature management in adult cardiac arrest patients.

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched on June 17, 2021 for clinical trials. The population included adult patients with cardiac arrest. The review included all aspects of targeted temperature management including timing, temperature, duration, method of induction and maintenance, and rewarming. Two investigators reviewed trials for relevance, extracted data, and assessed risk of bias. Data were pooled using random-effects models. Certainty of evidence was evaluated using GRADE.

RESULTS

The systematic search identified 32 trials. Risk of bias was assessed as intermediate for most of the outcomes. For targeted temperature management with a target of 32-34 °C vs. normothermia (which often required active cooling), 9 trials were identified, with six trials included in meta-analyses. Targeted temperature management with a target of 32-34 °C did not result in an improvement in survival (risk ratio: 1.08 [95%CI: 0.89, 1.30]) or favorable neurologic outcome (risk ratio: 1.21 [95%CI: 0.91, 1.61]) at 90 to 180 days after the cardiac arrest (low certainty of evidence). Three trials assessed different hypothermic temperature targets and found no difference in outcomes (low certainty of evidence). Ten trials were identified comparing prehospital cooling vs. no prehospital cooling with no improvement in survival (risk ratio: 1.01 [95%CI: 0.92, 1.11]) or favorable neurologic outcome (risk ratio: 1.00 [95%CI: 0.90, 1.11]) at hospital discharge (moderate certainty of evidence).

CONCLUSIONS

Among adult patients with cardiac arrest, the use of targeted temperature management at 32-34 °C, when compared to normothermia, did not result in improved outcomes in this meta-analysis. There was no effect of initiating targeted temperature management prior to hospital arrival. These findings warrant an update of international cardiac arrest guidelines.

Prognostic benefits of prior amiodarone or β-blocker use before the onset of ventricular arrhythmia with hemodynamic collapse

Although antiarrhythmic drugs have long been used for the suppression of various types of arrhythmias, their prior use before the onset of ventricular arrhythmia with hemodynamic collapse and the effect on prognosis is not well known. Data from 1004 consecutive patients with cardiovascular shock in the Japanese Circulation Society's Shock Registry were analyzed. Eighty-four cases of ventricular arrhythmia-induced shock and ROSC (return of spontaneous circulation) were divided into the prior amiodarone or β-blockers use group (Aβ group, n = 27) and the non-amiodarone and non-β-blockers use group (non-Aβ group; n = 57) based on treatment before the onset of those arrhythmias. Clinical outcomes related to hemodynamic collapse such as OHCA (out-of-hospital cardiovascular arrest) was less in the Aβ group [Aβ group, 11/26 (42%) vs. non-Aβ group, 41/56 (73%); p = 0.007]. Similarly, syncope was less common in the Aβ group than in the non-Aβ group [Aβ group 4/27 (15%) vs. non-Aβ group 27/57 (47%); p = 0.004]. Furthermore, prior amiodarone or β-blockers use before the onset of ventricular arrhythmias was strongly associated with both survival at discharge (odds ratio 3.19; 95% confidence interval 1.06-9.67; p = 0.040) and neurological outcomes at discharge (odds ratio 3.96; 95% confidence interval 1.32-11.85; p = 0.014) based on multivariate logistic regression analysis. Prior amiodarone or β-blockers use before the onset of malignant ventricular arrhythmia and maintaining appropriate blood concentrations in advance is associated with a good survival rate and better neurological outcomes after recovery from ventricular arrhythmia with hemodynamic collapse.

Resuscitation highlights in 2020

BACKGROUND

This review is the latest in a series of regular annual reviews undertaken by the editors and aims to highlight some of the key papers published in Resuscitation during 2020. The number of papers submitted to the Journal in 2020 increased by 25% on the previous year.MethodsHand-searching by the editors of all papers published in Resuscitation during 2020. Papers were selected based on then general interest and novelty and were categorised into general themes.ResultsA total of 103 papers were selected for brief mention in this review.ConclusionsResuscitation science continues to evolve rapidly and incorporate all links in the chain of survival.

Temporal Changes in Targeted Temperature Management for Out-of-Hospital Cardiac Arrest-Examining the Effect of the Targeted Temperature Management Trial: A Retrospective Cohort Study

Targeted temperature management (TTM) is recommended after out-of-hospital cardiac arrest (OHCA). However, interpretation of the evidence and translation into clinical practice, to realize benefits to patient outcomes may be inconsistent. This study aims to compare compliance with the recommended targeted temperatures and the use of intravascular temperature management (IVTM), as well as 90-day survival, before and after publication of the TTM trial. A single-center retrospective cohort study was conducted from 2010 to 2017. All comatose patients admitted to the intensive care unit after OHCA, who survived for ≥24 hours, were included. IVTM use was measured and TTM adherence was defined as the percentage time the core temperature was (1) within the guideline-recommended temperature range (initially 32-34°C, later modified to 32-36°C) for the first 24 hours, and (2) ≤37.5°C between 24 and 72 hours following admission. Multiple logistic regression analyses were performed for the use of IVTM and survival at 90 days. Of the 302 patients identified, 136 (45%) were pre-TTM, and 166 (55%) post-TTM. Baseline characteristics were similar between the groups. IVTM use decreased significantly (77.9% vs. 51.8%, p < 0.001) after the publication of the TTM trial. Adherence to the 32-34°C and 32-36°C targets was higher pre-TTM as compared with the post-TTM cohort (33.3% [0-66.7%] vs. 0% [0-16.7%], p < 0.001 and 83.3% [50.0-100%] vs. 36.7% [16.7-66.7%], p < 0.001, respectively). Time with temperature ≥37.5°C in the first 24 hours was higher post-TTM (p = < 0.001) but not between 24 and 72 hours. Ninety-day survival was 54.4% in the pre-TTM cohort and 44.0% post-TTM, (odds ratio 1.52 [0.96-2.40], p = 0.083). Adherence with recommended TTM decreased significantly following publication of the TTM trial and this was explained by a significant decrease in IVTM use. However, this concerning trend did not result in a statistically significant difference in survival.

Cardiac arrest: An interdisciplinary scoping review of the literature from 2019

Objectives

The Interdisciplinary Cardiac Arrest Research Review (ICARE) group was formed in 2018 to conduct a systematic annual search of peer-reviewed literature relevant to cardiac arrest. Now in its second year, the goals of the review are to illustrate best practices in research and help reduce compartmentalization of knowledge by disseminating clinically relevant advances in the field of cardiac arrest across disciplines.

Methods

An electronic search of PubMed using keywords related to cardiac arrest was conducted. Title and abstracts retrieved by these searches were screened for relevance, classified by article type (original research or review), and sorted into 7 categories. Screened manuscripts underwent standardized scoring of overall methodological quality and impact on the categorized fields of study by reviewer teams lead by a subject-matter expert editor. Articles scoring higher than 99 percentiles by category-type were selected for full critique. Systematic differences between editors’ and reviewers’ scores were assessed using Wilcoxon signed-rank test.

Results

A total of 3348 articles were identified on initial search; of these, 1364 were scored after screening for relevance and deduplication, and forty-five underwent full critique. Epidemiology & Public Health represented 24% of fully reviewed articles with Prehospital Resuscitation, Technology & Care, and In-Hospital Resuscitation & Post-Arrest Care Categories both representing 20% of fully reviewed articles. There were no significant differences between editor and reviewer scoring.

Conclusions

The sheer number of articles screened is a testament to the need for an accessible source calling attention to high-quality and impactful research and serving as a high-yield reference for clinicians and scientists seeking to follow the ever-growing body of cardiac arrest-related literature. This will promote further development of the unique and interdisciplinary field of cardiac arrest medicine.

Neck cooling induces blood pressure increase and peripheral vasoconstriction in healthy persons

Introduction

Noninvasive temperature modulation by localized neck cooling might be desirable in the prehospital phase of acute hypoxic brain injuries. While combined head and neck cooling induces significant discomfort, peripheral vasoconstriction, and blood pressure increase, localized neck cooling more selectively targets blood vessels that supply the brain, spares thermal receptors of the face and skull, and might therefore cause less discomfort cardiovascular side effects compared to head- and neck cooling. The purpose of this study is to assess the effects of noninvasive selective neck cooling on cardiovascular parameters and cerebral blood flow velocity (CBFV).

Methods

Eleven healthy persons (6 women, mean age 42 ± 11 years) underwent 90 min of localized dorsal and frontal neck cooling (EMCOOLS Brain.Pad™) without sedation. Before and after cooling onset, and after every 10 min of cooling, we determined rectal, tympanic, and neck skin temperatures. Before and after cooling onset, after 60- and 90-min cooling, we monitored RR intervals (RRI), systolic, diastolic blood pressures (BPsys, BPdia), laser Doppler skin blood flow (SBF) at the index finger pulp, and CBFV at the proximal middle cerebral artery (MCA). We compared values before and during cooling by analysis of variance for repeated measurements with post hoc analysis (significance: p < 0.05).

Results

Neck skin temperature dropped significantly by 9.2 ± 4.5 °C (minimum after 40 min), while tympanic temperature decreased by only 0.8 ± 0.4 °C (minimum after 50 min), and rectal temperature by only 0.2 ± 0.3 °C (minimum after 60 min of cooling). Index finger SBF decreased (by 83.4 ± 126.0 PU), BPsys and BPdia increased (by 11.2 ± 13.1 mmHg and 8.0 ± 10.1 mmHg), and heart rate slowed significantly while MCA-CBFV remained unchanged during cooling.

Conclusions

While localized neck cooling prominently lowered neck skin temperature, it had little effect on tympanic temperature but significantly increased BP which may have detrimental effects in patients with acute brain injuries.