Neuromuscular blockade during therapeutic hypothermia after cardiac arrest: Observational study of neurological and infectious outcomes

Neuromuscular blocking agents during targeted temperature management for out-of-hospital cardiac arrest patients

BACKGROUND

Neuromuscular blocking agents (NMBAs) can control shivering during targeted temperature management (TTM) of patients with cardiac arrest. However, the effectiveness of NMBA use during TTM on neurologic outcomes remains unclear. We aimed to evaluate the association between NMBA use during TTM and favorable neurologic outcomes after out-of-hospital cardiac arrest (OHCA).

MATERIALS AND METHODS

A multicenter, prospective, observational cohort study from 2019 to 2021. It included OHCA patients who received TTM after hospitalization. We conducted overlap weight propensity-score analyses after multiple imputation to evaluate the effect of NMBAs during TTM. The primary outcome was a favorable neurological outcome, defined as a cerebral performance category of 1 or 2 at discharge. Subgroup analyses were conducted based on initial monitored rhythm and brain computed tomography findings.

RESULTS

Of the 516 eligible patients, 337 received NMBAs during TTM. In crude analysis, the proportion of patients with favorable neurological outcome was significantly higher in the NMBA group (38.3% vs. 16.8%; risk difference (RD): 21.5%; 95% confidence interval (CI): 14.0% to 29.1%). In weighted analysis, a significantly higher proportion of patients in the NMBA group had a favorable neurological outcome compared to the non-NMBA group (32.7% vs. 20.9%; RD: 11.8%; 95% CI: 1.2% to 22.3%). In the subgroup with an initial shockable rhythm and no hypoxic encephalopathy, the NMBA group showed significantly higher proportions of favorable neurological outcomes.

CONCLUSIONS

The use of NMBAs during TTM was significantly associated with favorable neurologic outcomes at discharge for OHCA patients. NMBAs may have benefits in selected patients with initial shockable rhythm and without poor prognostic computed tomography findings.

Ensemble-Based Virtual Screening Led to the Discovery of Novel Lead Molecules as Potential NMBAs

Neuromuscular blocking agents (NMBAs) are routinely used during anesthesia to relax skeletal muscle. Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels; NMBAs can induce muscle paralysis by preventing the neurotransmitter acetylcholine (ACh) from binding to nAChRs situated on the postsynaptic membranes. Despite widespread efforts, it is still a great challenge to find new NMBAs since the introduction of cisatracurium in 1995. In this work, an effective ensemble-based virtual screening method, including molecular property filters, 3D pharmacophore model, and molecular docking, was applied to discover potential NMBAs from the ZINC15 database. The results showed that screened hit compounds had better docking scores than the reference compound d-tubocurarine. In order to further investigate the binding modes between the hit compounds and nAChRs at simulated physiological conditions, the molecular dynamics simulation was performed. Deep analysis of the simulation results revealed that ZINC257459695 can stably bind to nAChRs' active sites and interact with the key residue Asp165. The binding free energies were also calculated for the obtained hits using the MM/GBSA method. In silico ADMET calculations were performed to assess the pharmacokinetic properties of hit compounds in the human body. Overall, the identified ZINC257459695 may be a promising lead compound for developing new NMBAs as an adjunct to general anesthesia, necessitating further investigations.

Association between neuromuscular blocking agent use and outcomes among out-of-hospital cardiac arrest patients treated with extracorporeal cardiopulmonary resuscitation and target temperature management: A secondary analysis of the SAVE-J II study

Background

Neuromuscular blocking agents are used to control shivering in cardiac arrest patients treated with target temperature management. However, their effect on outcomes in patients treated with extracorporeal cardiopulmonary resuscitation is unclear.

Methods

This study was a secondary analysis of the SAVE-J II study, a retrospective multicenter study of 2175 out-of-hospital cardiac arrest patients treated with extracorporeal cardiopulmonary resuscitation in Japan. We classified patients into those who received neuromuscular blocking agents and those who did not and compared in-hospital mortality and incidence rates of favorable neurological outcome and in-hospital pneumonia between the groups using multivariable regression models and stabilized inverse probability weighting with propensity scores.

Results

Six hundred sixty patients from the SAVE-J II registry were analyzed. Neuromuscular blocking agents were used in 451 patients (68.3%). After adjusting for potential confounders, neuromuscular blocking agents use was not significantly associated with in-hospital mortality (aHR 0.88; 95% CI, 0.67-1.14), favorable neurological outcome (aOR 0.85; 95% CI, 0.60-1.11), or pneumonia (aOR 1.52; 95% CI, 0.85-2.71). The results for in-hospital mortality (aHR 0.89; 95% CI, 0.64-1.25), favorable neurological outcome (aOR 0.94; 95% CI, 0.59-1.48) and pneumonia (aOR 1.59; 95% CI, 0.74-3.41) were similar after weighting was performed.

Conclusions

Although data on the rationale for using neuromuscular blocking agents were unavailable, their use was not significantly associated with outcomes in out-of-hospital cardiac arrest patients treated with extracorporeal cardiopulmonary resuscitation and targeted temperature management. Neuromuscular blocking agents should be used based on individual clinical indications.

Association of multiple rib fractures with the frequency of pneumonia in the post-resuscitation period

Purpose

Successful cardiopulmonary resuscitation is associated with a high incidence of chest wall injuries. However, few studies have examined chest wall injury as a risk factor for respiratory complications after cardiopulmonary resuscitation. Therefore, herein, we investigated the association of multiple rib fractures on the incidence of post-resuscitation pneumonia.

Methods

This single-centre retrospective cohort study enrolled adult, nontraumatic, out-of-hospital cardiac arrest patients who maintained circulation for more than 48 h between June 2015 and May 2019. Rib fractures were evaluated by computed tomography on the day of hospital admission. The association with newly developed pneumonia within 7 days of hospitalisation was analysed using a Fine-Gray proportional hazards regression model adjusted for the propensity score of multiple rib fractures estimated from age, sex, presence of witnessed status, bystander CPR, initial rhythm, and total CPR time and for previously reported risk factors for pneumonia (therapeutic hypothermia and prophylactic antibiotics).

Results

Overall, 683 patients with out-of-hospital cardiac arrest were treated; 87 eligible cases were enrolled for analysis. Thirty-two (36.8%) patients had multiple rib fractures identified on computed tomography, and 35 (40.2%) patients developed pneumonia. The presence of multiple rib fractures was significantly associated with a higher incidence of pneumonia, consistently both with and without adjustment for background factors (unadjusted hazard ratio 4.63, 95% confidence interval: 2.35–9.13, p < 0.001; adjusted hazard ratio 4.03, 95% confidence interval: 2.08–7.82, p < 0.001).

Conclusions

Multiple rib fractures are independently associated with the development of pneumonia after successful resuscitation.

Neuromuscular Blockade for Cardiac Arrest Patients Treated With Targeted Temperature Management: A Systematic Review and Meta-Analysis

Background: Neuromuscular-blocking agents (NMBA) are often administered to control shivering in comatose cardiac arrest (CA) survivors during targeted temperature management (TTM) management. Thus, we performed a systematic review and meta-analysis to investigate the effectiveness and safety of NMBA in such a patient population. Methods: We searched for relevant studies in PubMed, Embase, and the Cochrane Library until 15 Jul 2021. Studies were included if they reported data on any of the predefined outcomes in adult comatose CA survivors managed with any NMBA regimens. The primary outcomes were mortality and neurological outcome. Results were expressed as odds ratio (OR) or mean difference (MD) with an accompanying 95% confidence interval (CI). Heterogeneity, sensitivity analysis, and publication bias were also investigated to test the robustness of the primary outcome. Data Synthesis: We included 12 studies (3 randomized controlled trials and nine observational studies) enrolling 11,317 patients. These studies used NMBA in three strategies: prophylactic NMBA, bolus NMBA if demanded, or managed without NMBA. Pooled analysis showed that CA survivors with prophylactic NMBA significantly improved both outcomes of mortality (OR 0.74; 95% CI 0.64-0.86; I 2 = 41%; p < 0.0001) and neurological outcome (OR 0.53; 95% CI 0.37-0.78; I 2 = 59%; p = 0.001) than those managed without NMBA. These results were confirmed by the sensitivity analyses and subgroup analyses. Only a few studies compared CA survivors receiving continuous versus bolus NMBA if demanded strategies and the pooled results showed no benefit in the primary outcomes between the two groups. Conclusion: Our results showed that using prophylactic NMBA strategy compared to the absence of NMBA was associated with improved mortality and neurologic outcome in CA patients undergoing TTM. However, more high-quality randomized controlled trials are needed to confirm our results.

Targeted Temperature Management After In-Hospital Cardiac Arrest: An Ancillary Analysis of Targeted Temperature Management for Cardiac Arrest With Nonshockable Rhythm Trial Data

BACKGROUND

Targeted temperature management (TTM) currently is the only treatment with demonstrated efficacy in attenuating the harmful effects on the brain of ischemia-reperfusion injury after cardiac arrest. However, whether TTM is beneficial in the subset of patients with in-hospital cardiac arrest (IHCA) remains unclear.

RESEARCH QUESTION

Is TTM at 33 °C associated with better neurological outcomes after IHCA in a nonshockable rhythm compared with targeted normothermia (TN; 37 °C)?

STUDY DESIGN AND METHODS

We performed a post hoc analysis of data from the published Targeted Temperature Management for Cardiac Arrest with Nonshockable Rhythm randomized controlled trial in 584 patients. We included the 159 patients with IHCA; 73 were randomized to 33 °C treatment and 86 were randomized to 37 °C treatment. The primary outcome was survival with a good neurologic outcome (cerebral performance category [CPC] score of 1 or 2) on day 90. Mixed multivariate adjusted logistic regression analysis was performed to determine whether survival with CPC score of 1 or 2 on day 90 was associated with type of temperature management after adjustment on baseline characteristics not balanced by randomization.

RESULTS

Compared with TN for 48 h, hypothermia at 33 °C for 24 h was associated with a higher percentage of patients who were alive with good neurologic outcomes on day 90 (16.4% vs 5.8%; P = .03). Day 90 mortality was not significantly different between the two groups (68.5% vs 76.7%; P = .24). By mixed multivariate analysis adjusted by Cardiac Arrest Hospital Prognosis score and circulatory shock status, hypothermia was associated significantly with good day 90 neurologic outcomes (OR, 2.40 [95% CI, 1.17-13.03]; P = .03).

INTERPRETATION

Hypothermia at 33 °C was associated with better day 90 neurologic outcomes after IHCA in a nonshockable rhythm compared with TN. However, the limited sample size resulted in wide CIs. Further studies of patients after cardiac arrest resulting from any cause, including IHCA, are needed.

Impact of rewarming rate on interleukin-6 levels in patients with shockable cardiac arrest receiving targeted temperature management at 33 °C: the ISOCRATE pilot randomized controlled trial

Purpose

While targeted temperature management (TTM) has been recommended in patients with shockable cardiac arrest (CA) and suggested in patients with non-shockable rhythms, few data exist regarding the impact of the rewarming rate on systemic inflammation. We compared serum levels of the proinflammatory cytokine interleukin-6 (IL6) measured with two rewarming rates after TTM at 33 °C in patients with shockable out-of-hospital cardiac arrest (OHCA).

Methods

ISOCRATE was a single-center randomized controlled trial comparing rewarming at 0.50 °C/h versus 0.25 °C/h in patients coma after shockable OHCA in 2016–2020. The primary outcome was serum IL6 level 24–48 h after reaching 33 °C. Secondary outcomes included the day-90 Cerebral Performance Category (CPC) and the 48-h serum neurofilament light-chain (NF-L) level.

Results

We randomized 50 patients. The median IL6 area-under-the-curve was similar between the two groups (12,389 [7256–37,200] vs. 8859 [6825–18,088] pg/mL h; P = 0.55). No significant difference was noted in proportions of patients with favorable day-90 CPC scores (13/25 patients at 0.25 °C/h (52.0%; 95% CI 31.3–72.2%) and 13/25 patients at 0.50 °C/h (52.0%; 95% CI 31.3–72.2%; P = 0.99)). Median NF-L levels were not significantly different between the 0.25 °C/h and 0.50 °C/h groups (76.0 pg mL, [25.5–3074.0] vs. 192 pg mL, [33.6–4199.0]; P = 0.43; respectively).

Conclusion

In our RCT, rewarming from 33 °C at 0.25 °C/h, compared to 0.50 °C/h, did not decrease the serum IL6 level after shockable CA. Further RCTs are needed to better define the optimal TTM strategy for patients with CA.

Trial registration ClinicalTrials.gov, NCT02555254. Registered September 14, 2015.

Take-Home Message: Rewarming at a rate of 0.25 °C/h, compared to 0.50 °C, did not result in lower serum IL6 levels after achievement of hypothermia at 33 °C in patients who remained comatose after shockable cardiac arrest. No associations were found between the slower rewarming rate and day-90 functional outcomes or mortality.

140-character Tweet: Rewarming at 0.25 °C versus 0.50 °C did not decrease serum IL6 levels after hypothermia at 33 °C in patients comatose after shockable cardiac arrest.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03842-9.

European Resuscitation Council and European Society of Intensive Care Medicine guidelines 2021: post-resuscitation care

The European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) have collaborated to produce these post-resuscitation care guidelines for adults, which are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. The topics covered include the post-cardiac arrest syndrome, diagnosis of cause of cardiac arrest, control of oxygenation and ventilation, coronary reperfusion, haemodynamic monitoring and management, control of seizures, temperature control, general intensive care management, prognostication, long-term outcome, rehabilitation and organ donation.

European Resuscitation Council and European Society of Intensive Care Medicine Guidelines 2021: Post-resuscitation care

The European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) have collaborated to produce these post-resuscitation care guidelines for adults, which are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. The topics covered include the post-cardiac arrest syndrome, diagnosis of cause of cardiac arrest, control of oxygenation and ventilation, coronary reperfusion, haemodynamic monitoring and management, control of seizures, temperature control, general intensive care management, prognostication, long-term outcome, rehabilitation, and organ donation.

Neuroprotective Treatment of Postanoxic Encephalopathy: A Review of Clinical Evidence

Postanoxic encephalopathy is the key determinant of death or disability after successful cardiopulmonary resuscitation. Animal studies have provided proof-of-principle evidence of efficacy of divergent classes of neuroprotective treatments to promote brain recovery. However, apart from targeted temperature management (TTM), neuroprotective treatments are not included in current care of patients with postanoxic encephalopathy after cardiac arrest. We aimed to review the clinical evidence of efficacy of neuroprotective strategies to improve recovery of comatose patients after cardiac arrest and to propose future directions. We performed a systematic search of the literature to identify prospective, comparative clinical trials on interventions to improve neurological outcome of comatose patients after cardiac arrest. We included 53 studies on 21 interventions. None showed unequivocal benefit. TTM at 33 or 36°C and adrenaline (epinephrine) are studied most, followed by xenon, erythropoietin, and calcium antagonists. Lack of efficacy is associated with heterogeneity of patient groups and limited specificity of outcome measures. Ongoing and future trials will benefit from systematic collection of measures of baseline encephalopathy and sufficiently powered predefined subgroup analyses. Outcome measurement should include comprehensive neuropsychological follow-up, to show treatment effects that are not detectable by gross measures of functional recovery. To enhance translation from animal models to patients, studies under experimental conditions should adhere to strict methodological and publication guidelines.

Intermittent versus continuous neuromuscular blockade during target temperature management after cardiac arrest: A nationwide observational study

PURPOSE

Whether intermittent or continuous neuromuscular-blocking agents (NMBAs) would be appropriate during target temperature management (TTM) after cardiac arrest remains unclear.

MATERIALS AND METHODS

In this retrospective cohort study, we utilized the Japanese Diagnosis Procedure Combination inpatient database from July 2010 to March 2018 and identified patients who received NMBAs during TTM after cardiac arrest on the day of admission. We compared the in-hospital mortality between the propensity-score-matched intermittent and continuous NMBA groups.

RESULTS

We identified 5584 eligible patients; 1488 received intermittent NMBAs and 4096 received continuous NMBAs. After propensity score matching, there was no significant difference in the in-hospital mortality between the intermittent and continuous NMBA groups (32.9% vs. 33.1%; odds ratio, 0.98; 95% confidence interval, 0.82-1.18). In subgroup analyses, in-hospital mortality of the continuous NMBA group was significantly higher than that of the intermittent NMBA group in patients aged ≥65 years (p for interaction = 0.021).

CONCLUSIONS

This large retrospective study did not suggest that intermittent NMBAs may be inferior to continuous NMBAs in terms of mortality reduction in the overall population receiving TTM for cardiac arrest. However, continuous NMBAs may be inferior to intermittent NMBAs for reducing mortality in elderly patients.

The association between neuromuscular blockade use during target temperature management and neurological outcomes

BACKGROUND

To date, no study has comprehensively analyzed the association between neuromuscular blockade (NMB) during target temperature management (TTM) and the neurological outcomes after out-of-hospital cardiac arrest (OHCA) using a multicenter dataset. We aimed to examine the association between NMB during TTM after cardiac arrest and neurological outcomes after OHCA.

METHODS

This study was a secondary analysis of the Japanese Population-based Utstein-style study with defibrillation and basic/advanced Life Support Education and implementation-Hypothermia (J-PULSE-HYPO) study registry. The exposure of the current study was the use of NMB during TTM. The primary outcome was favorable neurological outcome, i.e., a cerebral performance category of 1-2, at hospital discharge.

RESULTS

Of the 452 patients with OHCA enrolled in the J-PULSE-HYPO study, 431 were analyzed. NMB was used in 353 patients (81.9%). Multivariable logistic regression analysis revealed that NMB use was not independently associated with favorable outcomes [odds ratio (OR), 0.96; 95% confidence interval (CI), 0.42-2.18; p = .918)] or survival at discharge (OR, 0.83; 95% CI, 0.31-2.02; p = .688). After adjusting the covariates, the predicted probabilities did not reveal significant differences between NMB use and non-NMB use in the respective mean (95% CI) values for favorable neurological outcomes [53.6 (50.2-57.0) % vs. 58.0 (50.4-65.6) %, p = .304], and survival rates [77.1 (74.7-79.5) % vs. 75.8 (70.5-81.0) %, p = .647].

CONCLUSIONS

The NMB use during TTM was not associated with favorable neurological outcomes and survival rate in patients with OHCA.

Association Between Target Temperature Variability and Neurologic Outcomes for Patients Receiving Targeted Temperature Management at 36°C After Cardiac Arrest: A Retrospective Cohort Study

Maintaining strict temperature control during the maintenance phase of targeted temperature management (TTM) after cardiac arrest may be an important component of clinical care. Temperature variability outside of the goal temperature range may lessen the benefit of TTM and worsen neurologic outcomes. The purpose of this retrospective study of 186 adult patients (70.4% males, mean age 53.8 ± 15.7 years) was to investigate the relationship between body temperature variability (at least one body temperature measurement outside of 36°C ± 0.5°C) during the maintenance phase of TTM at 36°C after cardiac arrest and neurologic outcome at hospital discharge. Patients with temperature variability (n = 124 [66.7%]) did not have significantly higher odds of poor neurologic outcome compared with those with no temperature variability (odds ratio [OR] = 1.01, 95% confidence interval [CI] = 0.36-2.82). Use of neuromuscular blocking agents (NMBAs) and having an initial shockable rhythm were associated with both higher odds of good neurologic outcome (shockable rhythm: OR = 10.77, 95% CI = 4.30-26.98; NMBA use: OR = 4.54, 95% CI = 1.34-15.40) and survival to hospital discharge (shockable rhythm: OR = 5.90, 95% CI = 2.65-13.13; NMBA use: OR = 3.03, 95% CI = 1.16-7.90). In this cohort of postcardiac arrest comatose survivors undergoing TTM at 36°C, having temperature variability during maintenance phase did not significantly impact neurologic outcome or survival.

Targeted Temperature Management for Cardiac Arrest with Nonshockable Rhythm

BACKGROUND

Moderate therapeutic hypothermia is currently recommended to improve neurologic outcomes in adults with persistent coma after resuscitated out-of-hospital cardiac arrest. However, the effectiveness of moderate therapeutic hypothermia in patients with nonshockable rhythms (asystole or pulseless electrical activity) is debated.

METHODS

We performed an open-label, randomized, controlled trial comparing moderate therapeutic hypothermia (33°C during the first 24 hours) with targeted normothermia (37°C) in patients with coma who had been admitted to the intensive care unit (ICU) after resuscitation from cardiac arrest with nonshockable rhythm. The primary outcome was survival with a favorable neurologic outcome, assessed on day 90 after randomization with the use of the Cerebral Performance Category (CPC) scale (which ranges from 1 to 5, with higher scores indicating greater disability). We defined a favorable neurologic outcome as a CPC score of 1 or 2. Outcome assessment was blinded. Mortality and safety were also assessed.

RESULTS

From January 2014 through January 2018, a total of 584 patients from 25 ICUs underwent randomization, and 581 were included in the analysis (3 patients withdrew consent). On day 90, a total of 29 of 284 patients (10.2%) in the hypothermia group were alive with a CPC score of 1 or 2, as compared with 17 of 297 (5.7%) in the normothermia group (difference, 4.5 percentage points; 95% confidence interval [CI], 0.1 to 8.9; P = 0.04). Mortality at 90 days did not differ significantly between the hypothermia group and the normothermia group (81.3% and 83.2%, respectively; difference, -1.9 percentage points; 95% CI, -8.0 to 4.3). The incidence of prespecified adverse events did not differ significantly between groups.

CONCLUSIONS

Among patients with coma who had been resuscitated from cardiac arrest with nonshockable rhythm, moderate therapeutic hypothermia at 33°C for 24 hours led to a higher percentage of patients who survived with a favorable neurologic outcome at day 90 than was observed with targeted normothermia. (Funded by the French Ministry of Health and others; HYPERION ClinicalTrials.gov number, NCT01994772.).

Variation in Sedation and Neuromuscular Blockade Regimens on Outcome After Cardiac Arrest

OBJECTIVES

Sedation and neuromuscular blockade protocols in patients undergoing targeted temperature management after cardiac arrest address patient discomfort and manage shivering. These protocols vary widely between centers and may affect outcomes.

DESIGN

Consecutive patients admitted to 20 centers after resuscitation from cardiac arrest were prospectively entered into the International Cardiac Arrest Registry between 2006 and 2016. Additional data about each center's sedation and shivering management practice were obtained via survey. Sedation and shivering practices were categorized as escalating doses of sedation and minimal or no neuromuscular blockade (sedation and shivering practice 1), sedation with continuous or scheduled neuromuscular blockade (sedation and shivering practice 2), or sedation with as-needed neuromuscular blockade (sedation and shivering practice 3). Good outcome was defined as Cerebral Performance Category score of 1 or 2. A logistic regression hierarchical model was created with two levels (patient-level data with standard confounders at level 1 and hospitals at level 2) and sedation and shivering practices as a fixed effect at the hospital level. The primary outcome was dichotomized Cerebral Performance Category at 6 months.

SETTING

Cardiac arrest receiving centers in Europe and the United states from 2006 to 2016 PATIENTS:: Four-thousand two-hundred sixty-seven cardiac arrest patients 18 years old or older enrolled in the International Cardiac Arrest Registry.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The mean age was 62 ± 15 years, 36% were female, 77% out-of-hospital arrests, and mean ischemic time was 24 (± 18) minutes. Adjusted odds ratio (for age, return of spontaneous circulation, location of arrest, witnessed, initial rhythm, bystander cardiopulmonary resuscitation, defibrillation, medical history, country, and size of hospital) was 1.13 (0.74-1.73; p = 0.56) and 1.45 (1.00-2.13; p = 0.046) for sedation and shivering practice 2 and sedation and shivering practice 3, respectively, referenced to sedation and shivering practice 1.

CONCLUSION

Cardiac arrest patients treated at centers using as-needed neuromuscular blockade had increased odds of good outcomes compared with centers using escalating sedation doses and avoidance of neuromuscular blockade, after adjusting for potential confounders. These findings should be further investigated in prospective studies.

Continuous neuromuscular blockade infusion for out-of-hospital cardiac arrest patients treated with targeted temperature management: A multicenter randomized controlled trial

Introduction

The aim of this trial was to investigate the effect of a continuous infusion of a neuromuscular blockade (NMB) in comatose out-of-hospital cardiac arrest (OHCA) subjects who underwent targeted temperature management (TTM).

Methods

In this open-label, multicenter trial, subjects resuscitated from OHCA were randomly assigned to receive either NMB (38 subjects) or placebo (43 subjects) for 24 hours. Sedatives and analgesics were given according to the protocol of each hospital during TTM. The primary outcome was serum lactate levels at 24 hours after drug infusion. The secondary outcomes included in-hospital mortality, a poor neurological outcome at hospital discharge, changes in lactate levels, changes in the PaO₂:FiO₂ ratio over time and muscle weakness as assessed by the Medical Research Council (MRC) scale.

Results

Eighty-one subjects (NMB group: median age, 65.5 years, 30 male patients; placebo group: median age, 61.0 years, 29 male patients) were enrolled in this trial. No difference in the serum lactate level at 24 hours was observed between the NMB (2.8 [1.2–4.0]) and placebo (3.6 [1.8–5.2]) groups (p = 0.238). In-hospital mortality and a poor neurologic outcome at discharge did not differ between the two groups. No significant difference in the PaO₂:FiO₂ ratio over time (p = 0.321) nor the MRC score (p = 0.474) was demonstrated.

Conclusions

In OHCA subjects who underwent TTM, a continuous infusion of NMB did not reduce lactate levels and did not improve survival or neurological outcome at hospital discharge. Our results indicated a limited potential for the routine use of NMB during early TTM. However, this trial may be underpowered to detect clinical differences, and future research should be conducted.

The prognostic value of bispectral index and suppression ratio monitoring after out-of-hospital cardiac arrest: a prospective observational study

Background

We investigated the ability of bispectral index (BIS) monitoring to predict poor neurological outcome in out-of-hospital cardiac arrest (OHCA) patients fully treated according to guidelines.

Results

In this prospective, observational study, 77 successfully resuscitated OHCA patients were enrolled in whom BIS, suppression ratio (SR) and electromyographic (EMG) values were continuously monitored during the first 36 h after the initiation of targeted temperature management at 33 °C. The Cerebral Performance Category (CPC) scale was used to define patients’ outcome at 180 days after OHCA (CPC 1–2: good–CPC 3–5: poor neurological outcome). Using mean BIS and SR values calculated per hour, receiver operator characteristics curves were constructed to determine the optimal time point and threshold to predict poor neurological outcome. At 180 days post-cardiac arrest, 39 patients (51%) had a poor neurological outcome. A mean BIS value ≤ 25 at hour 12 predicted poor neurological outcome with a sensitivity of 49% (95% CI 30–65%), a specificity of 97% (95% CI 85–100%) and false positive rate (FPR) of 6% (95% CI 0–29%) [AUC: 0.722 (0.570–0.875); p = 0.006]. A mean SR value ≥ 3 at hour 23 predicted poor neurological with a sensitivity of 74% (95% CI 56–87%), a specificity of 92% (95% CI 78–98%) and FPR of 11% (95% CI 3–29%) [AUC: 0.836 (0.717–0.955); p < 0.001]. No relationship was found between mean EMG and BIS < 25 (R² = 0.004; p = 0.209).

Conclusion

This study found that mean BIS ≤ 25 at hour 12 and mean SR ≥ 3 at hour 23 might be used to predict poor neurological outcome in an OHCA population with a presumed cardiac cause. Since no correlation was observed between EMG and BIS < 25, our calculated BIS threshold might assist with poor outcome prognostication following OHCA.

Use of Neuromuscular Blockers During Therapeutic Hypothermia After Cardiac Arrest: A Nursing Protocol

BACKGROUND

Neuromuscular blockers used to prevent shivering during therapeutic hypothermia in comatose patients after out-of-hospital cardiac arrest are associated with adverse events.

OBJECTIVE

To assess the influence of a nurse-implemented protocol on use of neuromuscular blockers in patients treated with 24-hour therapeutic hypothermia after out-of-hospital cardiac arrest.

METHODS

A before and after study was done in a 24-bed cardiac arrest center. During the before period, paralysis was maintained by continuous infusion of vecuronium during therapeutic hypothermia. During the after period, a nurse-implemented protocol was used to strictly control use of neuromuscular blockers. The primary outcome measure was duration of infusion of neuromuscular blockers; secondary end points included rates of ventilator-associated pneumonia and intensive care unit mortality.

RESULTS

Among the 22 patients in the before group and the 23 patients in the after group, most were men (78%) with a median age of 66 years. Baseline characteristics were similar between the 2 groups. Median duration of sedation was 36 hours, shorter in the after group (34 hours) than in the before group (38 hours; P = .02). Median duration of infusion of neuromuscular blockers was significantly shorter in the after group (6 hours) than in the before group (33 hours; P < .001). Ventilator-associated pneumonia occurred more frequently in the before group (45%) than in the after group (13%; P = .02). Overall intensive care unit mortality rate was 58%, similar in both groups (P = .44).

CONCLUSION

Use of a nurse-implemented protocol to reduce use of neuromuscular blockers is feasible.

Continuous versus intermittent neuromuscular blockade in patients during targeted temperature management after resuscitation from cardiac arrest-A randomized, double blinded, double dummy, clinical trial

AIM OF THE STUDY

Current guidelines recommend targeted temperature management to improve neurological outcome after cardiac arrest. Evidence regarding an ideal sedative/analgesic regimen including skeletal muscle paralysis is limited.

METHODS

Patients were randomized to either a continuous administration of rocuronium (continuous-NMB-group) or to a continuous administration of saline supplemented by rocuronium bolus administration if demanded (bolus-NMB-group). The primary outcome was the number of shivering episodes. Secondary outcomes included survival and neurological status one year after cardiac arrest, time to awakening, length of stay as well as required cumulative dose of rocuronium, midazolam and fentanyl.

RESULTS

Sixty-three patients (32 continuous-NMB-group; 31 bolus-NMB-group) were enrolled. Differences in baseline characteristics were not significant. Shivering episodes were detected in 94% of the patients in the bolus-NMB-group compared to 25% of the patients receiving continuous rocuronium infusion (p<0.01). The continuous-NMB-group received significant lower doses of midazolam (4.3±0.8mg/kg vs. 5.1±0.9mg/kg, p<0.01) and fentanyl (62±14μg/kg vs. 71±7μg/kg, p<0.01), but higher cumulative doses of rocuronium (7.8±1.8mg/kg vs. 2.3±1.6mg/kg, p<0.01). Earlier awakening (2 [IQR 2;3] vs. 4 [IQR 2;7.5] days, p=0.04) and decreased length of stay at the ICU (6 [IQR 3;5.9] vs. 10 [IQR 5;15] days, p=0.03) were observed in the continuous-NMB-group. There were no significant differences in survival and quality of life 12 months after cardiac arrest.

CONCLUSIONS

Continuous neuromuscular blockade during the first day after resuscitation reduced shivering, midazolam and fentanyl requirement, time to awakening and discharge from intensive care unit. There were no differences in overall survival, cooling rate and time to target temperature.

Neuromuscular blockade requirement is associated with good neurologic outcome in cardiac arrest survivors treated with targeted temperature management

PURPOSE

We examined the association between neuromuscular blockade (NMB) requirements and outcomes and lactate clearance in cardiac arrest survivors treated with targeted temperature management (TTM).

METHODS

We included consecutive adult cardiac arrest survivors treated with TTM between 2012 and 2015. NMB use was categorized into 3 groups: no NMB, bolus NMB (intermittent bolus use), and continuous NMB (continuous infusion). Serum lactate levels were measured on admission and at 12h, 24h, and 48h after admission. The primary outcome was neurologic outcome at discharge. The secondary outcomes were in-hospital mortality and lactate clearance.

RESULTS

In total, 309 patients were included. Of these, 206 (66.7%) and 73 (23.6%) were discharged with poor neurologic outcome and death, respectively. Multivariate analysis revealed that continuous NMB, as opposed to no NMB use, was associated with decreased poor neurologic outcomes (odds ratio [OR], 0.317; 95% confidence interval [CI], 0.124-0.815) and decreased in-hospital mortality (OR, 0.414; 95% CI, 0.183-0.941). There were no differences in lactate clearance between the NMB groups.

CONCLUSION

Continuous NMB requirement was associated with improved neurologic outcome and decreased in-hospital mortality in cardiac arrest survivors treated with TTM. The NMB requirement was not associated with lactate clearance.

Critical Care Management Focused on Optimizing Brain Function After Cardiac Arrest

The discussion of neurocritical care management in post-cardiac arrest syndrome (PCAS) has generally focused on target values used for targeted temperature management (TTM). There has been less attention paid to target values for systemic and cerebral parameters to minimize secondary brain damage in PCAS. And the neurologic indications for TTM to produce a favorable neurologic outcome remain to be determined. Critical care management of PCAS patients is fundamental and essential for both cardiologists and general intensivists to improve neurologic outcome, because definitive therapy of PCAS includes both special management of the cause of cardiac arrest, such as coronary intervention to ischemic heart disease, and intensive management of the results of cardiac arrest, such as ventilation strategies to avoid brain ischemia. We reviewed the literature and the latest research about the following issues and propose practical care recommendations. Issues are (1) prediction of TTM candidate on admission, (2) cerebral blood flow and metabolism and target value of them, (3) seizure management using continuous electroencephalography, (4) target value of hemodynamic stabilization and its method, (5) management and analysis of respiration, (6) sedation and its monitoring, (7) shivering control and its monitoring, and (8) glucose management. We hope to establish standards of neurocritical care to optimize brain function and produce a favorable neurologic outcome.

Neuromuscular Blockade in the 21st Century Management of the Critically Ill Patient

Neuromuscular blockings agents (NMBAs) have a controversial role in the ventilatory and medical management of critical illness. The clinical concern surrounding NMBA-induced complications stems from evidence presented in the 2002 clinical practice guidelines, but new evidence from subsequent randomized trials and studies provides a more optimistic outlook about the application of NMBAs in the ICU. Furthermore, changes in the delivery of critical care, such as protocolized care pathways, minimizing or interrupting sedation, increased monitoring techniques, and overall improvements in reducing immobility, have created a modern, 21st century ICU environment whereby NMBAs may be administered safely. In this article we start with a review of the mechanism of action, side effects, and pharmacology of commonly used NMBAs. We then address the rationale for NMBA use for an expanding number of indications (endotracheal intubation, acute respiratory distress syndrome, status asthmaticus, increased intracranial and intra-abdominal pressure, and therapeutic hypothermia after cardiac arrest), with an emphasis on NMBA use in facilitating lung-protective ventilation for respiratory failure. We end with an appraisal over the importance of monitoring depth of paralysis and the concerns of complications, such as prolonged skeletal muscle weakness. In the context of adequate sedation and analgesia, monitored NMBA use (continuous or bolus administration) can be considered for the small number of clinical indications in critically ill patients for which evidence currently exists.

Analgesia, sedation, and neuromuscular blockade during targeted temperature management after cardiac arrest

The approach to sedation, analgesia, and neuromuscular blockade during targeted temperature management (TTM) remains largely unstudied, forcing clinicians to adapt previous research from other patient environments. During TTM, very little data guide drug selection, doses, and specific therapeutic goals. Sedation should be deep enough to prevent awareness during neuromuscular blockade, but titration is complex as metabolism and clearance are delayed for almost all drugs during hypothermia. Deeper sedation is associated with prolonged intensive care unit (ICU) and ventilator therapy, increased delirium and infection, and delayed wakening which can confound early critical neurological assessments, potentially resulting in erroneous prognostication and inappropriate withdrawal of life support. We review the potential therapeutic goals for sedation, analgesia, and neuromuscular blockade during TTM; the adverse events associated with that treatment; data suggesting that TTM and organ dysfunction impair drug metabolism; and controversies and potential benefits of specific monitoring. We also highlight the areas needing better research to guide our therapy.

Neurocritical care update

This update comprises six important topics under neurocritical care that require reevaluation. For post-cardiac arrest brain injury, the evaluation of the injury and its corresponding therapy, including temperature modulation, is required. Analgosedation for target temperature management is an essential strategy to prevent shivering and minimizes endogenous stress induced by catecholamine surges. For severe traumatic brain injury, the diverse effects of therapeutic hypothermia depend on the complicated pathophysiology of the condition. Continuous electroencephalogram monitoring is an essential tool for detecting nonconvulsive status epilepticus in the intensive care unit (ICU). Neurocritical care, including advanced hemodynamic monitoring, is a fundamental approach for delayed cerebral ischemia following subarachnoid hemorrhage. We must be mindful of the high percentage of ICU patients who may develop sepsis-associated brain dysfunction.

Therapeutic hypothermia after nonshockable cardiac arrest: the HYPERION multicenter, randomized, controlled, assessor-blinded, superiority trial

BACKGROUND

Meta-analyses of nonrandomized studies have provided conflicting data on therapeutic hypothermia, or targeted temperature management (TTM), at 33°C in patients successfully resuscitated after nonshockable cardiac arrest. Nevertheless, the latest recommendations issued by the International Liaison Committee on Resuscitation and by the European Resuscitation Council recommend therapeutic hypothermia. New data are available on the adverse effects of therapeutic hypothermia, notably infectious complications. The risk/benefit ratio of therapeutic hypothermia after nonshockable cardiac arrest is unclear.

METHODS

HYPERION is a multicenter (22 French ICUs) trial with blinded outcome assessment in which 584 patients with successfully resuscitated nonshockable cardiac arrest are allocated at random to either TTM between 32.5 and 33.5°C (therapeutic hypothermia) or TTM between 36.5 and 37.5°C (therapeutic normothermia) for 24 hours. Both groups are managed with therapeutic normothermia for the next 24 hours. TTM is achieved using locally available equipment. The primary outcome is day-90 neurological status assessed by the Cerebral Performance Categories (CPC) Scale with dichotomization of the results (1 + 2 versus 3 + 4 + 5). The primary outcome is assessed by a blinded psychologist during a semi-structured telephone interview of the patient or next of kin. Secondary outcomes are day-90 mortality, hospital mortality, severe adverse events, infections, and neurocognitive performance. The planned sample size of 584 patients will enable us to detect a 9% absolute difference in day-90 neurological status with 80% power, assuming a 14% event rate in the control group and a two-sided Type 1 error rate of 4.9%. Two interim analyses will be performed, after inclusion of 200 and 400 patients, respectively.

DISCUSSION

The HYPERION trial is a multicenter, randomized, controlled, assessor-blinded, superiority trial that may provide an answer to an issue of everyday relevance, namely, whether TTM is beneficial in comatose patients resuscitated after nonshockable cardiac arrest. Furthermore, it will provide new data on the tolerance and adverse events (especially infectious complications) of TTM at 32.5-33.5°C.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01994772 .