Hemodynamics and Vasopressor Support During Targeted Temperature Management at 33°C Versus 36°C After Out-of-Hospital Cardiac Arrest: A Post Hoc Study of the Target Temperature Management Trial*

The Evolving Paradigm of Individualized Postresuscitation Care After Cardiac Arrest

The postresuscitation period after a cardiac arrest is characterized by a wide range of physiological derangements. Variations between patients include preexisting medical problems, the underlying cause of the cardiac arrest, presence or absence of hemodynamic and circulatory instability, severity of the ischemia-reperfusion injury, and resuscitation-related injuries such as pulmonary aspiration and rib or sternal fractures. Although protocols can be applied to many elements of postresuscitation care, the widely disparate clinical condition of cardiac arrest survivors requires an individualized approach that stratifies patients according to their clinical profile and targets specific treatments to patients most likely to benefit. This article describes such an individualized approach, provides a practical framework for evaluation and triage at the bedside, and reviews concerns specific to all members of the interprofessional postresuscitation care team.

Usefulness of Serum B-Type Natriuretic Peptide Levels in Comatose Patients Resuscitated from Out-of-Hospital Cardiac Arrest to Predict Outcome

N-terminal pro-B-type natriuretic (NT-proBNP) is expressed in the heart and brain, and serum levels are elevated in acute heart and brain diseases. We aimed to assess the possible association between serum levels and neurological outcome and death in comatose patients resuscitated from out-of-hospital cardiac arrest (OHCA). Of the 939 comatose OHCA patients enrolled and randomized in the Targeted Temperature Management (TTM) trial to TTM at 33°C or 36°C for 24 hours, 700 were included in the biomarker substudy. Of these, 647 (92%) had serum levels of NT-proBNP measured 24, 48, and 72 hours after return of spontaneous circulation (ROSC). Neurological outcome was evaluated by the Cerebral Performance Category (CPC) score and modified Rankin Scale (mRS) at 6 months. Six hundred thirty-eight patients (99%) had serum NT-proBNP levels ≥125 pg/ml. Patients with TTM at 33°C had significantly lower NT-proBNP serum levels (median 1,472 pg/ml) than those in the 36°C group (1,914 pg/ml) at 24 hours after ROSC, p <0.01 but not at 48 and 72 hours. At 24 hours, an increase in NT-proBNP quartile was associated with death (Plogrank <0.0001). In addition, NT-proBNP serum levels > median were independently associated with poor neurological outcome (odds ratio, ORCPC 2.02, CI 1.34 to 3.05, p <0.001; ORmRS 2.28, CI 1.50 to 3.46, p <0.001) adjusted for potential confounders. The association was diminished at 48 and 72 hours after ROSC. In conclusion, NT-proBNP serum levels are increased in comatose OHCA patients. Furthermore, serum NT-proBNP levels are affected by level of TTM and are associated with death and poor neurological outcome.

Vasopressor requirement during targeted temperature management for out-of-hospital cardiac arrest caused by acute myocardial infarction without cardiogenic shock

Objective

We investigated whether patients with out-of-hospital cardiac arrest (OHCA) due to an acute myocardial infarction without cardiogenic shock required higher doses of vasopressors with low targeted temperature management (TTM) after return of spontaneous circulation.

Methods

We included consecutive comatose patients resuscitated from OHCA between January 2011 and December 2013. Patients with return of spontaneous circulation, regional wall motion abnormality on echocardiography, and coronary artery stenosis of ≥70% on percutaneous coronary artery angiography were enrolled. These patients received 36°C TTM or 33°C TTM following approval of TTM by patients’ next-of-kin (36°C and 33°C TTM groups, respectively). The cumulative vasopressor index was compared between groups.

Results

During induction phase, dose of vasopressors did not differ between groups. In the maintenance phase, the norepinephrine dose was 0.37±0.57 and 0.26±0.91 µg·kg^-1·min^-1 in the 33°C and 36°C TTM groups, respectively (P<0.01). During the rewarming phase, the norepinephrine and dopamine doses were 0.49±0.60 and 9.67±9.60 mcg·kg^-1·min^-1 in the 33°C TTM group and 0.14±0.46 and 3.13±7.19 mcg·kg^-1·min^-1 in the 36°C TTM group, respectively (P<0.01). The median cumulative vasopressor index was 8 (interquartile range, 3 to 8) and 4 (interquartile range, 0 to 8) in the 33°C and 36°C TTM groups, respectively (P=0.03).

Conclusion

In this study, patients with OHCA due to acute myocardial infarction without cardiogenic shock had an elevated vasopressor requirement with 33°C TTM compared to 36°C TTM during the maintenance and rewarming phases.

Haemodynamic and ventilator management in patients following cardiac arrest

PURPOSE OF REVIEW

The purpose of this study is to review the recent literature describing how to assess and treat postcardiac arrest syndrome associated haemodynamics and manage oxygenation and ventilation derangements.

RECENT FINDINGS

Postcardiac arrest syndrome is a well described entity that includes systemic ischemia-reperfusion response, myocardial dysfunction and neurologic dysfunction. Continued resuscitation in the hours to days following return of spontaneous circulation (ROSC) is important to increase the likelihood of long-term survival and neurological recovery. Post-ROSC hypotension is common and associated with worse outcome. Myocardial dysfunction peaks in the first 24  h following ROSC and in survivors resolves over the next few days. Hyperoxemia (paO₂>300  mmHg) and hypoxemia (paO₂<60  mmHg) are associated with worse outcomes and hyperventilation may exacerbate cerebral ischemic injury by decreasing cerebral oxygenation.

SUMMARY

Patients who are successfully resuscitated from cardiac arrest often have hypotension and myocardial dysfunction. Careful attention to haemodynamic and ventilator management targeting normal blood pressure, normoxemia and normocapnia may help to avoid secondary organ injury and potentially improve outcomes.

Targeted temperature management in emergency medicine: current perspectives

Landmark trials in 2002 showed that therapeutic hypothermia (TH) after out-of-hospital cardiac arrest due to ventricular tachycardia or ventricular fibrillation resulted in improved likelihood of good neurologic recovery compared to standard care without TH. Since that time, TH has been frequently instituted in a wide range of cardiac arrest patients regardless of initial heart rhythm. Recent evidence has evaluated how, when, and to what degree TH should be instituted in cardiac arrest victims. We outline early evidence, as well as recent trials, regarding the use of TH or targeted temperature management in these patients. We also provide evidence-based suggestions for the institution of targeted temperature management/TH in a variety of emergency medicine settings.

Myocardial Dysfunction and Shock after Cardiac Arrest

Postarrest myocardial dysfunction includes the development of low cardiac output or ventricular systolic or diastolic dysfunction after cardiac arrest. Impaired left ventricular systolic function is reported in nearly two-thirds of patients resuscitated after cardiac arrest. Hypotension and shock requiring vasopressor support are similarly common after cardiac arrest. Whereas shock requiring vasopressor support is consistently associated with an adverse outcome after cardiac arrest, the association between myocardial dysfunction and outcomes is less clear. Myocardial dysfunction and shock after cardiac arrest develop as the result of preexisting cardiac pathology with multiple superimposed insults from resuscitation. The pathophysiology involves cardiovascular ischemia/reperfusion injury and cardiovascular toxicity from excessive levels of inflammatory cytokine activation and catecholamines, among other contributing factors. Similar mechanisms occur in myocardial dysfunction after cardiopulmonary bypass, in sepsis, and in stress-induced cardiomyopathy. Hemodynamic stabilization after resuscitation from cardiac arrest involves restoration of preload, vasopressors to support arterial pressure, and inotropic support if needed to reverse the effects of myocardial dysfunction and improve systemic perfusion. Further research is needed to define the role of postarrest myocardial dysfunction on cardiac arrest outcomes and identify therapeutic strategies.

Adverse events associated with poor neurological outcome during targeted temperature management and advanced critical care after out-of-hospital cardiac arrest

Introduction

The aim of this study was to investigate the association of adverse events (AEs) during targeted temperature management (TTM) and other AEs and concomitant treatments during the advanced critical care period with poor neurological outcome at hospital discharge in adult out-of-hospital cardiac arrest (OHCA) patients.

Methods

This was a retrospective study using Korean Hypothermia Network registry data of adult OHCA patients treated with TTM in 24 teaching hospitals throughout South Korea from 2007 to 2012. Demographic characteristics, resuscitation and post-resuscitation variables, AEs, and concomitant treatments during TTM and the advanced critical care were collected. The primary outcome was poor neurological outcome, defined as a cerebral performance category (CPC) score of 3–5 at hospital discharge. The AEs and concomitant treatments were individually entered into the best multivariable predictive model of poor neurological outcome to evaluate the associations between each variable and outcome.

Results

A total of 930 patients, including 704 for whom a complete dataset of AEs and covariates was available for multivariable modeling, were included in the analysis; 476 of these patients exhibited poor neurological outcome [CPC 3 = 50 (7.1 %), CPC 4 = 214 (30.4 %), and CPC 5 = 212 (30.1 %)]. Common AEs included hyperglycemia (45.6 %), hypokalemia (31.3 %), arrhythmia (21.3 %) and hypotension (29 %) during cooling, and hypotension (21.6 %) during rewarming. Bleeding (5 %) during TTM was a rare AE. Common AEs during the advanced critical care included pneumonia (39.6 %), myoclonus (21.9 %), seizures (21.7 %) and hypoglycemia within 72 hours (23 %). After adjusting for independent predictors of outcome, cooling- and rewarming-related AEs were not significantly associated with poor neurological outcome. However, sepsis, myoclonus, seizure, hypoglycemia within 72 hours and anticonvulsant use during the advanced critical care were associated with poor neurological outcome [adjusted odds ratios (95 % confidence intervals) of 3.12 (1.40–6.97), 3.72 (1.93–7.16), 4.02 (2.04–7.91), 2.03 (1.09–3.78), and 1.69 (1.03–2.77), respectively]. Alternatively, neuromuscular blocker use was inversely associated with poor neurological outcome (0.48 [0.28–0.84]).

Conclusions

Cooling- and rewarming-related AEs were not associated with poor neurological outcome at hospital discharge. Sepsis, myoclonus, seizure, hypoglycemia within 72 hours and anticonvulsant use during the advanced critical care period were associated with poor neurological outcome at hospital discharge in our study.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0991-9) contains supplementary material, which is available to authorized users.