Time to start of cardiopulmonary resuscitation and the effect of target temperature management at 33°C and 36°C

Hypothermia versus normothermia in patients with cardiac arrest and shockable rhythm: a secondary analysis of the TTM-2 study

BACKGROUND

The aim of this study was to assess whether hypothermia increased survival and improved functional outcome when compared with normothermia in out-of-hospital cardiac arrest (OHCA) patients with similar characteristics than in previous randomized studies showing benefits for hypothermia.

METHODS

Post hoc analysis of a pragmatic, multicenter, randomized clinical trial (TTM-2, NCT02908308). In this analysis, the subset of patients included in the trial who had similar characteristics to patients included in one previous randomized trial and randomized to hypothermia at 33 °C or normothermia (i.e. target < 37.8 °C) were considered. The primary outcome was survival at 6 months; secondary outcomes included favorable functional outcome at 6 months, defined as a modified Rankin scale of 0-3. Time-to-death and the occurrence of adverse events were also reported.

RESULTS

From a total of 1891 included in the TTM-2 study, 600 (31.7%) were included in the analysis, 294 in the hypothermia and 306 in the normothermia group. At 6 months, 207 of the 294 patients (70.4%) in the hypothermia group and 220 of the 306 patients (71.8%) in the normothermia group had survived (relative risk with hypothermia, 0.96; 95% confidence interval [CI], 0.81 to 1.15; P = 0.71). Also, 198 of the 294 (67.3%) in the hypothermia group and 202 of the 306 (66.0%) in the normothermia group had a favorable functional outcome (relative risk with hypothermia, 1.03; 95% CI, 0.87 to 1.23; P = 0.79). There was a significant increase in the occurrence of arrythmias in the hypothermia group (62/294, 21.2%) when compared to the normothermia group (43/306, 14.1%-OR 1.49, 95% CI 1.05-2.14; p = 0.026).

CONCLUSIONS

In this study, hypothermia at 33˚C did not improve survival or functional outcome in a subset of patients with similar cardiac arrest characteristics to patients in whom benefit from hypothermia was shown in prior studies.

Temperature Control After In-Hospital Cardiac Arrest: A Randomized Clinical Trial

BACKGROUND

This study was conducted to determine the effect of hypothermic temperature control after in-hospital cardiac arrest (IHCA) on mortality and functional outcome as compared with normothermia.

METHODS

An investigator initiated, open-label, blinded-outcome-assessor, multicenter, randomized controlled trial comparing hypothermic temperature control (32-34°C) for 24 h with normothermia after IHCA in 11 hospitals in Germany. The primary endpoint was all-cause mortality after 180 days. Secondary end points included in-hospital mortality and favorable functional outcome using the Cerebral Performance Category scale after 180 days. A Cerebral Performance Category score of 1 or 2 was defined as a favorable functional outcome.

RESULTS

A total of 1055 patients were screened for eligibility and 249 patients were randomized: 126 were assigned to hypothermic temperature control and 123 to normothermia. The mean age of the cohort was 72.6±10.4 years, 64% (152 of 236) were male, 73% (166 of 227) of cardiac arrests were witnessed, 25% (57 of 231) had an initial shockable rhythm, and time to return of spontaneous circulation was 16.4±10.5 minutes. Target temperature was reached within 4.2±2.8 hours after randomization in the hypothermic group and temperature was controlled for 48 hours at 37.0°±0.9°C in the normothermia group. Mortality by day 180 was 72.5% (87 of 120) in hypothermic temperature control arm, compared with 71.2% (84 of 118) in the normothermia group (relative risk, 1.03 [95% CI, 0.79-1.40]; P=0.822). In-hospital mortality was 62.5% (75 of 120) in the hypothermic temperature control as compared with 57.6% (68 of 118) in the normothermia group (relative risk, 1.11 [95% CI, 0.86-1.46, P=0.443). Favorable functional outcome (Cerebral Performance Category 1 or 2) by day 180 was 22.5% (27 of 120) in the hypothermic temperature control, compared with 23.7% (28 of 118) in the normothermia group (relative risk, 1.04 [95% CI, 0.78-1.44]; P=0.822). The study was prematurely terminated because of futility.

CONCLUSIONS

Hypothermic temperature control as compared with normothermia did not improve survival nor functional outcome at day 180 in patients presenting with coma after IHCA. The HACA in-hospital trial (Hypothermia After Cardiac Arrest in-hospital) was underpowered and may have failed to detect clinically important differences between hypothermic temperature control and normothermia.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique Identifier: NCT00457431.

Hypothermic to ischemic ratio and mortality in post-cardiac arrest patients

BACKGROUND

We studied the associations between ischemia and hypothermia duration, that is, the hypothermic to ischemic ratio (H/I ratio), with mortality in patients included in a trial on two durations of targeted temperature management (TTM) at 33°C.

METHODS

The TTH48 (NCT01689077) trial compared 24 and 48 hours of TTM in patients after cardiac arrest. We calculated the hypothermia time from return of spontaneous circulation (ROSC) until the patient reached 37°C after TTM and the ischemic time from CA to ROSC. We compared continuous variables with the Mann-Whitney U test. Using COX regression, we studied the independent association of the logarithmically transformed H/I ratio and time to death as well as interaction between time to ROSC, hypothermia duration, and intervention group. We visualized the predictive ability of variables with receiver operating characteristic curve analysis.

RESULTS

Of the 338 patients, 237 (70%) survived for 6 months. The H/I ratio was 155 (IQR 111-238) in survivors and 114 (IQR 80-169) in non-survivors (P < .001). In a Cox regression model including factors associated with outcome in univariate analysis, the logarithmically transformed H/I ratio was a significant predictor of outcome (hazard ratio 0.52 (0.37-0.72, P = .001)). After removing an outlier, we found no interaction between time to ROSC and intervention group (P = .55) or hypothermia duration in quartiles (P = .07) with mortality. There was no significant difference in the area under the curve (AUC) between time to ROSC and H/I ratio (ΔAUC 0.03 95% CI -0.006-0.07, P = .10).

CONCLUSIONS

We did not find any consistent evidence of a modification of the effect of TTM based on ischemia duration.

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.).

Targeted temperature management guided by the severity of hyperlactatemia for out-of-hospital cardiac arrest patients: a post hoc analysis of a nationwide, multicenter prospective registry

Background

The International Liaison Committee on Resuscitation guidelines recommend target temperature management (TTM) between 32 and 36 °C for patients after out-of-hospital cardiac arrest, but did not indicate patient-specific temperatures. The association of serum lactate concentration and neurological outcome in out-of-hospital cardiac arrest patient has been reported. The study aim was to investigate the benefit of 32–34 °C in patients with various degrees of hyperlactatemia compared to 35–36 °C.

Methods

This study was a post hoc analysis of the Japanese Association for Acute Medicine out-of-hospital cardiac arrest registry between June 2014 and December 2015. Patients with complete targeted temperature management and lactate data were eligible. Patients were stratified to mild (< 7 mmol/l), moderate (< 12 mmol/l), or severe (≥ 12 mmol/l) hyperlactatemia group based on lactate concentration after return of spontaneous circulation. They were subdivided into 32–34 °C or 35–36 °C groups. The primary endpoint was an adjusted predicted probability of 30-day favorable neurological outcome, defined as a cerebral performance category score of 1 or 2.

Result

Of 435 patients, 139 had mild, 182 had moderate, and 114 had severe hyperlactatemia. One hundred and eight (78%) with mild, 128 with moderate (70%), and 83 with severe hyperlactatemia (73%) received TTM at 32–34 °C. The adjusted predicted probability of a 30-day favorable neurological outcome following severe hyperlactatemia was significantly greater with 32–34 °C (27.4%, 95% confidence interval: 22.0–32.8%) than 35–36 °C (12.4%, 95% CI 3.5–21.2%; p = 0.005). The differences in outcomes in those with mild and moderate hyperlactatemia were not significant.

Conclusions

In OHCA patients with severe hyperlactatemia, the adjusted predicted probability of 30-day favorable neurological outcome was greater with TTM at 32–34 °C than with TTM at 35–36 °C. Further evaluation is needed to determine whether TTM at 32–34 °C can improve neurological outcomes in patients with severe hyperlactatemia after out-of-hospital cardiac arrest.

Comparison of in-hospital use of mechanical chest compression devices for out-of-hospital cardiac arrest patients: AUTOPULSE vs LUCAS

This study aimed to investigate the prognostic difference between AUTOPULSE and LUCAS for out-of-hospital cardiac arrest (OHCA) adult patients.A retrospective observational study was performed nationwide. Adult OHCA patients after receiving in-hospital mechanical chest compression from 2012 to 2016 were included. The primary outcomes were sustained return of spontaneous circulation (ROSC) of more than 20 minutes and survival to discharge.Among 142,906 OHCA patients, 820 patients were finally included. In multivariate analysis, female (OR, 0.57; 95% CI, 0.33-0.99), witnessed arrest (OR, 2.10; 95% CI, 1.20-3.69), and arrest cause of non-cardiac origin (OR, 0.25; 95% CI, 0.10-0.62) were significantly associated with the increase in ROSC. LUCAS showed a lower survival than AUTOPULSE (OR, 0.23; 95% CI, 0.06-0.84), although it showed no significant association with ROSC. Percutaneous coronary intervention (OR, 6.30; 95% CI, 1.53-25.95) and target temperature management (TTM; OR, 7.30; 95% CI, 2.27-23.49) were the independent factors for survival. We categorized mechanical CPR recipients by witness to compare prognostic effectiveness of AUTOPULSE and LUCAS. In the witnessed subgroup, female (OR, 0.46; 95% CI, 0.24-0.89) was a prognostic factor for ROSC and shockable rhythm (OR, 5.04; 95% CI, 1.00-25.30), percutaneous coronary intervention (OR, 12.42; 95% CI, 2.04-75.53), and TTM (OR, 9.03; 95% CI, 1.86-43.78) for survival. In the unwitnessed subgroup, no prognostic factors were found for ROSC, and TTM (OR, 99.00; 95% CI, 8.9-1100.62) was found to be an independent factor for survival. LUCAS showed no significant increase in ROSC or survival in comparison with AUTOPULSE in both subgroups.The in-hospital use of LUCAS may have a deleterious effect for survival compared with AUTOPULSE.

Added value of the DIC score and of D-dimer to predict outcome after successfully resuscitated out-of-hospital cardiac arrest

BACKGROUND

Recent Korean data suggest a high prevalence of overt disseminated intravascular coagulation (DIC) and a good predictive performance of the ISTH DIC score in successfully resuscitated out-of-hospital cardiac arrest.

OBJECTIVES

We hypothesised that in a European cohort of resuscitated out-of-hospital cardiac arrest patients the prevalence of DIC is substantially lower. Furthermore, the determination of D-dimer levels at admission, but not the DIC score, could improve mortality prediction above traditional predictors.

PATIENTS/METHODS

Data were extracted from a prospective cardiac arrest registry including patients admitted between 2006 and 2015, who achieved return of spontaneous circulation and had parameters for DIC score calculation available. The primary outcome was the prevalence of overt DIC at admission. Secondary outcomes included the association of overt DIC with 30-day mortality and the contribution of the DIC score and D-dimer levels to 30-day mortality prediction using logistic regression. Three stepwise models were evaluated by receiver-operating-characteristic analysis.

RESULTS

Out of 1179 patients 388 were included in the study. Overt DIC was present in 8% of patients and associated with substantial 30-day mortality (83% vs. 39%). The AUC for model 1, including traditional mortality predictors, was 0.83. The inclusion of D-dimer levels significantly improved prognostication above traditional predictors (model 3, AUC 0.89), whereas the inclusion of the DIC Score had no effect on mortality prediction (model 2, AUC 0.83).

CONCLUSION

Overt DIC was rare in a European cohort of out-of-hospital cardiac arrest patients. D-dimer levels improved 30-day mortality prediction and provided added value to assess early mortality risk after successful resuscitation.

Neurologic Recovery After Cardiac Arrest: a Multifaceted Puzzle Requiring Comprehensive Coordinated Care

OPINION STATEMENT

Surviving cardiac arrest (CA) requires a longitudinal approach with multiple levels of responsibility, including fostering a culture of action by increasing public awareness and training, optimization of resuscitation measures including frequent updates of guidelines and their timely implementation into practice, and optimization of post-CA care. This clearly goes beyond resuscitation and targeted temperature management. Brain-directed physiologic goals should dictate the post-CA management, as accumulating evidence suggests that the degree of hypoxic brain injury is the main determinant of survival, regardless of the etiology of arrest. Early assessment of the need for further hemodynamic and electrophysiologic cardiac interventions, adjusting ventilator settings to avoid hyperoxia/hypoxia while targeting high-normal to mildly elevated PaCO₂, maintaining mean arterial blood pressures >65 mmHg, evaluating for and treating seizures, maintaining euglycemia, and aggressively pursuing normothermia are key steps in reducing the bioenergetic failure that underlies secondary brain injury. Accurate neuroprognostication requires a multimodal approach with standardized assessments accounting for confounders while recognizing the importance of a delayed prognostication when there is any uncertainty regarding outcome. The concept of a highly specialized post-CA team with expertise in the management of post-CA syndrome (mindful of the brain-directed physiologic goals during the early post-resuscitation phase), TTM, and neuroprognostication, guiding the comprehensive care to the CA survivor, is likely cost-effective and should be explored by institutions that frequently care for these patients. Finally, providing tailored rehabilitation care with systematic reassessment of the needs and overall goals is key for increasing independence and improving quality-of-life in survivors, thereby also alleviating the burden on families. Emerging evidence from multicenter collaborations advances the field of resuscitation at an incredible pace, challenging previously well-established paradigms. There is no more room for "conventional wisdom" in saving the survivors of cardiac arrest.