Targeted temperature management with hypothermia for comatose patients after cardiac arrest

Longer Periods of Hypothermia Provide Greater Protection Against Focal Ischemia: A Systematic Review of Animal Studies Manipulating Treatment Duration

Decades of animal research show therapeutic hypothermia (TH) to be potently neuroprotective after cerebral ischemic injuries. While there have been some translational successes, clinical efficacy after ischemic stroke is unclear. One potential reason for translational failures could be insufficient optimization of dosing parameters. In this study, we conducted a systematic review of the PubMed database to identify all preclinical controlled studies that compared multiple TH durations following focal ischemia, with treatment beginning at least 1 hour after ischemic onset. Six studies met our inclusion criteria. In these six studies, six of seven experiments demonstrated an increase in cerebroprotection at the longest duration tested. The average effect size (mean Cohen's d ± 95% confidence interval) at the shortest and longest durations was 0.4 ± 0.3 and 1.9 ± 1.1, respectively. At the longest durations, this corresponded to percent infarct volume reductions between 31.2% and 83.9%. Our analysis counters previous meta-analytic findings that there is no relationship, or an inverse relationship between TH duration and effect size. However, underreporting often led to high or unclear risks of bias for each study as gauged by the SYRCLE Risk of Bias tool. We also found a lack of investigations of the interactions between duration and other treatment considerations (e.g., method, delay, and ischemic severity). With consideration of methodological limitations, an understanding of the relationships between treatment parameters is necessary to determine proper "dosage" of TH, and should be further studied, considering clinical failures that contrast with strong cerebroprotective results in most animal studies.

Navigating the 'Triangle of Death': A Multidisciplinary Approach in Severe Multi-Trauma Management

This case report details the challenging management of a 45-year-old male construction worker who suffered severe multiple injuries after a fall and subsequent collision with cement mixers. The patient presented with extensive injuries, including amputation, fractures and internal bleeding, leading to a state known as the 'triangle of death'. Despite the initial grim prognosis, evidenced by an ISS score of 28 and a mortality risk coefficient of 89.56%, the patient was successfully resuscitated and managed through a multidisciplinary approach. This included damage control resuscitation, emergency vascular interventions and targeted temperature management for brain protection. The patient's recovery highlights the effectiveness of comprehensive trauma management and the critical role of coordinated care in severe multi-trauma cases.

Characterization of Circulating Cold Shock Proteins FGF21 and RBM3 in a Multi-Center Study of Pediatric Cardiac Arrest

Fibroblast Growth Factor 21 (FGF21) is a neuroprotective hormone induced by cold exposure that targets the β-klotho co-receptor. β-klotho is abundant in the newborn brain but decreases rapidly with age. RNA-Binding Motif 3 (RBM3) is a potent neuroprotectant upregulated by FGF21 in hypothermic conditions. We characterized serum FGF21 and RBM3 levels in patients enrolled in a prospective multi-center study of pediatric cardiac arrest (CA) via a secondary analysis of samples collected to evaluate brain injury biomarkers. Patients (n = 111) with remnant serum samples available from at least two of three available timepoints (0-24, 24-48 or 48-72 hours post-resuscitation) were included. Serum samples from 20 healthy controls were used for comparison. FGF21 was measured by Luminex and internally validated enzyme-linked immunoassay (ELISA). RBM3 was measured by internally validated ELISA. Of postarrest patients, 98 were managed with normothermia, while 13 were treated with therapeutic hypothermia (TH). FGF21 increased >20-fold in the first 24 hours postarrest versus controls (681 pg/mL [200-1864] vs. 29 pg/mL [15-51], n = 99 vs. 19, respectively, p < 0.0001, median [interquartile range]) with no difference in RBM3. FGF21 did not differ by sex, while RBM3 was increased in females versus males at 48-72 hours postarrest (1866 pg/mL [873-5176] vs. 1045 pg/mL [535-2728], n = 40 vs. 54, respectively, p < 0.05). Patients requiring extracorporeal membrane oxygenation (ECMO) postresuscitation had increased FGF21 versus those who did not at 48-72 hours (6550 pg/mL [1455-66,781] vs. 1213 pg/mL [480-3117], n = 7 vs 74, respectively, p < 0.05). FGF21 and RBM3 did not correlate (Spearman's rho = 0.004, p = 0.97). We conclude that in a multi-center study of pediatric CA patients where normothermic targeted temperature management was largely used, FGF21 was markedly increased postarrest versus control and highest in patients requiring ECMO postresuscitation. RBM3 was sex-dependent. We provide a framework for future studies examining the effect of TH on FGF21 or use of FGF21 therapy after pediatric CA.

Association between early lactate-related variables and 6-month neurological outcome in out-of-hospital cardiac arrest patients

INTRODUCTION

The role of lactate measurement in out-of-hospital cardiac arrest (OHCA) survivors remains controversial. We assessed the association between early lactate-related variables, OHCA characteristics, and long-term neurological outcome.

METHODS

In OHCA patients who received targeted temperature management, lactate levels were measured at 0, 12, and 24 h after the return of spontaneous circulation. We calculated lactate clearance and time-weighted cumulative lactate (TWCL), which represent the area under the time-lactate curve. The area under the receiver operating characteristic curve (AUC) and the adjusted odds ratios (AORs) of lactate-related variables for predicting 6-month poor outcome (Cerebral Performance Category 3-5) were evaluated. Interactions between lactate variables and characteristics of OHCA were evaluated by a multivariable logistic model with interaction terms and subgroup analysis.

RESULTS

A total of 347 OHCA patients were included. After adjustment, higher lactate levels at the three time points were associated with a poor outcome (AOR 1.10 [95% CI, 1.03-1.18], AOR 1.15 [95% CI, 1.02-1.29], and AOR 1.36 [95% CI, 1.15-1.60], respectively), while TWCL was the only lactate kinetics variable associated with a poor outcome (AOR 1.29 [95% CI, 1.12-1.49]). We identified several interactions between lactate-related variables and OHCA characteristics. In particular, the AUC of TWCL was excellent in cases of noncardiac etiology (AUC 0.92 [95% CI, 0.86-0.96] but only moderate in cardiac etiology (AUC 0.69 [95% CI, 0.62-0.75]).

CONCLUSIONS

Early lactate levels, especially at 24 h, and TWCL were independent predictors of neurologic outcome in these patients, whereas lactate clearance was not. The prognostic ability of lactate-related variables varied depending on the OHCA characteristics.

Differences in Pathophysiology and Treatment Efficacy Based on Heterogeneous Out-of-Hospital Cardiac Arrest

Out-of-hospital cardiac arrest (OHCA) is heterogeneous in terms of etiology and severity. Owing to this heterogeneity, differences in outcome and treatment efficacy have been reported from case to case; however, few reviews have focused on the heterogeneity of OHCA. We conducted a literature review to identify differences in the prognosis and treatment efficacy in terms of CA-related waveforms (shockable or non-shockable), age (adult or pediatric), and post-CA syndrome severity and to determine the preferred treatment for patients with OHCA to improve outcomes.

Distribution and elimination kinetics of midazolam and metabolites after post-resuscitation care: a prospective observational study

Administration of sedatives for post-resuscitation care can complicate the determination of the optimal timing to avoid inappropriate, pessimistic prognostications. This prospective study aimed to investigate the distribution and elimination kinetics of midazolam (MDZ) and its metabolites, and their association with awakening time. The concentrations of MDZ and its seven metabolites were measured immediately and at 4, 8, 12, and 24 h after the discontinuation of MDZ infusion, using liquid chromatography-tandem mass spectrometry. The area under the time-plasma concentration curve from 0 to 24 h after MDZ discontinuation (AUClast) was calculated based on the trapezoidal rule. Of the 15 enrolled patients, seven awakened after the discontinuation of MDZ infusion. MDZ and three of its metabolites were major compounds and their elimination kinetics followed a first-order elimination profile. In the multivariable analysis, only MDZ was associated with awakening time (AUClast: R2 = 0.59, p = 0.03; AUCinf: R2 = 0.96, p < 0.001). Specifically, a 0.001% increase in MDZ AUC was associated with a 1% increase in awakening time. In the individual regression analysis between MDZ concentration and awakening time, the mean MDZ concentration at awakening time was 16.8 ng/mL. The AUC of MDZ is the only significant factor associated with the awakening time.

Differential Effects of Targeted Temperature Management on Sex-Dependent Outcomes After Experimental Asphyxial Cardiac Arrest

Asphyxial cardiac arrest (ACA) survivors face lasting neurological disability from hypoxic ischemic brain injury. Sex differences in long-term outcomes after cardiac arrest (CA) are grossly understudied and underreported. We used rigorous targeted temperature management (TTM) to understand its influence on survival and lasting sex-specific neurological and neuropathological outcomes in a rodent ACA model. Adult male and female rats underwent either sham or 5-minute no-flow ACA with 18 hours TTM at either ∼37°C (normothermia) or ∼36°C (mild hypothermia). Survival, temperature, and body weight (BW) were recorded over the 14-day study duration. All rats underwent neurological deficit score (NDS) assessment on days 1-3 and day 14. Hippocampal pathology was assessed for cell death, degenerating neurons, and microglia on day 14. Although ACA females were less likely to achieve return of spontaneous circulation (ROSC), post-ROSC physiology and biochemical profiles were similar between sexes. ACA females had significantly greater 14-day survival, NDS, and BW recovery than ACA males at normothermia (56% vs. 29%). TTM at 36°C versus 37°C improved 14-day survival in males, producing similar survival in male (63%) versus female (50%). There were no sex or temperature effects on CA1 histopathology. We conclude that at normothermic conditions, sex differences favoring females were observed after ACA in survival, NDS, and BW recovery. We achieved a clinically relevant ACA model using TTM at 36°C to improve long-term survival. This model can be used to more fully characterize sex differences in long-term outcomes and test novel acute and chronic therapies.

Effect of adjuvant thiamine and ascorbic acid administration on the neurologic outcomes of out-of-hospital cardiac arrest patients: A before-and-after study

AIM

This study aimed to evaluate the impact of early thiamine and ascorbic acid administration on the neurologic outcome in out-of-hospital cardiac arrest (OHCA) patients treated with targeted temperature management (TTM).

METHODS

This before-and-after cohort study used data extracted from two hospitals of the Korean Hypothermia Network prospective registry. The treatment group incorporated patients enrolled from December 2019 to May 2021, that received intravenous thiamine (200 mg) and ascorbic acid (3 g) at 12-hour intervals for a total of six doses. The control group incorporated those enrolled from May 2018 to November 2019. The one-month good neurologic outcome, defined as a Cerebral Performance Category score ≤ 2, between the groups was evaluated using inverse probability of treatment weighting (IPTW).

RESULTS

Among the 234 OHCA survivors with TTM, 102 were included in the treatment group and 132 were included in the control group. The one-month (31.4 % vs. 29.5 %, respectively; P = 0.76) good neurologic outcome rates did not differ between the treatment and control groups. After adjusting using the IPTW, vitamin supplementation was not associated with good neurologic outcome (odds ratio [OR], 1.134; 95 % confidence interval [CI], 0.644-1.999; P = 0.66). In subgroup analysis, vitamin administration was significantly associated with a good neurologic outcome in older (≥65 years) patients (adjusted OR, 5.53; 95 % CI, 1.21-25.23; P = 0.03).

CONCLUSION

Adjuvant thiamine and ascorbic acid administration in OHCA survivors with TTM did not improve their neurologic outcome after one month. Further clinical trials are warranted.

Electroencephalography Prediction of Neurological Outcomes After Hypoxic-Ischemic Brain Injury: A Systematic Review and Meta-Analysis

Background. Predicting neurological outcomes after hypoxic-ischemic brain injury (HIBI) is difficult. Objective. Electroencephalography (EEG) can identify acute and subacute brain abnormalities after hypoxic brain injury and predict HIBI recovery. We examined EEG's ability to predict neurologic outcomes following HIBI. Method. A PRISMA-compliant search was conducted in the Medline, Embase, Cochrane, and Central databases until January 2023. EEG-predicted neurological outcomes in HIBI patients were selected from relevant perspective and retrospective cohort studies. RevMan did meta-analysis, while QDAS2 assessed research quality. Results. Eleven studies with 3761 HIBI patients met the inclusion and exclusion criteria. We aggregated study-level estimates of sensitivity and specificity for EEG patterns determined a priori using random effect bivariate and univariate meta-analysis when appropriate. Positive indicators and anatomical area heterogeneity impacted prognosis accuracy. Funnel plots analyzed publication bias. Significant heterogeneity of greater than 80% was among the included studies with P < 0.001. The area under the curve was 0.94, the threshold effect was P < 0.001, and the sensitivity and specificity, with 95% confidence intervals, were 0.91 (0.84-0.99) and 0.86 (0.75-0.97). EEG detects status epilepticus and burst suppression with good sensitivity, specificity, and little probability of false-negative impairment result attribution. Study quality varied by domain, but patient flow and timing were well conducted in all. Conclusion. EEG can predict the outcome of HIBI with good prognostic accuracy, but more standardized cross-study protocols and descriptions of EEG patterns are needed to better evaluate its prognostic use for patients with HIBI.

Quantitative analysis of early apparent diffusion coefficient values from MRIs for predicting neurological prognosis in survivors of out-of-hospital cardiac arrest: an observational study

BACKGROUND

This study aimed to quantitatively analyse ultra-early brain diffusion-weighted magnetic resonance imaging (DW-MRI) findings to determine the apparent diffusion coefficient (ADC) threshold associated with neurological outcomes in comatose survivors of out-of-hospital cardiac arrest (OHCA).

METHODS

This retrospective study included adult survivors of comatose OHCA who underwent DW-MRI imaging scans using a 3-T MRI scanner within 6 h of the return of spontaneous circulation (ROSC). We investigated the association between neurological outcomes and ADC values obtained through voxel-based analysis on DW-MRI. Additionally, we constructed multivariable logistic regression models with pupillary light reflex (PLR), serum neuron-specific enolase (NSE), and ADC values as independent variables to predict poor neurological outcomes. The primary outcome was poor neurological outcome 6 months after ROSC, determined by the Cerebral Performance Category 3-5.

RESULTS

Overall, 131 patients (26% female) were analysed, of whom 74 (57%) showed poor neurological outcomes. The group with a poor neurological outcome had lower mean whole brain ADC values (739.1 vs. 787.1 × 10-6 mm/s) and higher percentages of voxels with ADC below threshold in all ranges (250-1150) (all P < 0.001). The mean whole brain ADC values (area under the receiver operating characteristic curve [AUC] 0.83) and the percentage of voxels with ADC below 600 (AUC 0.81) had the highest sensitivity of 51% (95% confidence interval [CI] 39.4-63.1; cut-off value ≤ 739.2 × 10-6 mm2/s and > 17.2%, respectively) when the false positive rate (FPR) was 0%. In the multivariable model, which also included PLR, NSE, and mean whole brain ADC values, poor neurological outcome was predicted with the highest accuracy (AUC 0.91; 51% sensitivity). This model showed more accurate prediction and sensitivity at an FPR of 0% than did the combination of PLR and NSE (AUC 0.86; 30% sensitivity; P = 0.03).

CONCLUSIONS

In this cohort study, early voxel-based quantitative ADC analysis after ROSC was associated with poor neurological outcomes 6 months after cardiac arrest. The mean whole brain ADC value demonstrated the highest sensitivity when the FPR was 0%, and including it in the multivariable model improved the prediction of poor neurological outcomes.

Temperature control after cardiac arrest

Managing temperature is an important part of post-cardiac arrest care. Fever or hyperthermia during the first few days after cardiac arrest is associated with worse outcomes in many studies. Clinical data have not determined any target temperature or duration of temperature management that clearly improves patient outcomes. Current guidelines and recent reviews recommend controlling temperature to prevent hyperthermia. Higher temperatures can lead to secondary brain injury by increasing seizures, brain edema and metabolic demand. Some data suggest that targeting temperature below normal could benefit select patients where this pathology is common. Clinical temperature management should address the physiology of heat balance. Core temperature reflects the heat content of the head and torso, and changes in core temperature result from changes in the balance of heat production and heat loss. Clinical management of patients after cardiac arrest should include measurement of core temperature at accurate sites and monitoring signs of heat production including shivering. Multiple methods can increase or decrease heat loss, including external and internal devices. Heat loss can trigger compensatory reflexes that increase stress and metabolic demand. Therefore, any active temperature management should include specific pharmacotherapy or other interventions to control thermogenesis, especially shivering. More research is required to determine whether individualized temperature management can improve outcomes.

Preliminary Prognostication for Good Neurological Outcomes in the Early Stage of Post-Cardiac Arrest Care

We investigated prognostic strategies for predicting good outcomes in the early stage of post-cardiac-arrest care using multiple prognostic tests that are available until 24 h after the return of spontaneous circulation (ROSC). A retrospective analysis was conducted on 138 out-of-hospital cardiac-arrest patients who underwent prognostic tests, including the gray-white-matter ratio (GWR-BG), the Glasgow Coma Scale motor (GCS-M) score before sedative administration, and the neuron-specific enolase (NSE) level measured at 24 h after the ROSC. We investigated the prognostic performances of the tests as single predictors and in various combination strategies. Classification and regression-tree analysis were used to provide a reliable model for the risk stratification. Out of all the patients, 55 (44.0%) had good outcomes. The NSE level showed the highest prognostic performance as a single prognostic test and provided improved specificities (>70%) and sensitivities (>98%) when used in combination strategies. Low NSE levels (≤32.1 ng/mL) and high GCS-M (≥4) scores identified good outcomes without misclassification. The overall accuracy for good outcomes was 81.8%. In comatose patients with low NSE levels or high GCS-M scores, the premature withdrawal of life-sustaining therapy should be avoided, thereby complying with the formal prognostication-strategy algorithm after at least 72 h from the ROSC.