High Level of Endotoxemia Following Out-of-Hospital Cardiac Arrest Is Associated With Severity and Duration of Postcardiac Arrest Shock*:

Delayed CCL23 response is associated with poor outcomes after cardiac arrest

Chemokines, a family of chemotactic cytokines, mediate leukocyte migration to and entrance into inflamed tissue, contributing to the intensity of local inflammation. We performed an analysis of chemokine and immune cell responses to cardiac arrest (CA). Forty-two patients resuscitated from cardiac arrest were analyzed, and twenty-two patients who underwent coronary artery bypass grafting (CABG) surgery were enrolled. Quantitative antibody array, chemokines, and endotoxin quantification were performed using the patients blood. Analysis of CCL23 production in neutrophils obtained from CA patients and injected into immunodeficient mice after CA and cardiopulmonary resuscitation (CPR) were done using flow cytometry. The levels of CCL2, CCL4, and CCL23 are increased in CA patients. Temporal dynamics were different for each chemokine, with early increases in CCL2 and CCL4, followed by a delayed elevation in CCL23 at forty-eight hours after CA. A high level of CCL23 was associated with an increased number of neutrophils, neuron-specific enolase (NSE), worse cerebral performance category (CPC) score, and higher mortality. To investigate the role of neutrophil activation locally in injured brain tissue, we used a mouse model of CA/CPR. CCL23 production was increased in human neutrophils that infiltrated mouse brains compared to those in the peripheral circulation. It is known that an early intense inflammatory response (within hours) is associated with poor outcomes after CA. Our data indicate that late activation of neutrophils in brain tissue may also promote ongoing injury via the production of CCL23 and impair recovery after cardiac arrest.

Immune cell expression patterns of CD39/CD73 ectonucleotidases in rodent models of cardiac arrest and resuscitation

Background

Cardiac arrest (CA) is a significant public health concern. There is the high imminent mortality and survival in those who are resuscitated is substantively compromised by the post-CA syndrome (PCAS), characterized by multiorgan ischemia-reperfusion injury (IRI). The inflammatory response in PCAS is complex and involves various immune cell types, including lymphocytes and myeloid cells that have been shown to exacerbate organ IRI, such as myocardial infarction. Purinergic signaling, as regulated by CD39 and CD73, has emerged as centrally important in the context of organ-specific IRI. Hence, comprehensive understanding of such purinergic responses may be likewise imperative for improving outcomes in PCAS.

Methods

We have investigated alterations of immune cell populations after CA by utilizing rodent models of PCAS. Blood and spleen were collected after CA and resuscitation and underwent flow cytometry analysis to evaluate shifts in CD3+CD4+ helper T cells, CD3+CD8a+ cytotoxic T cells, and CD4/CD8a ratios. We then examined the expression of CD39 and CD73 across diverse cell types, including myeloid cells, T lymphocytes, and B lymphocytes.

Results

In both rat and mouse models, there were significant increases in the frequency of CD3+CD4+ T lymphocytes in PCAS (rat, P < 0.01; mouse, P < 0.001), with consequently elevated CD4/CD8a ratios in whole blood (both, P < 0.001). Moreover, CD39 and CD73 expression on blood leukocytes were markedly increased (rat, P < 0.05; mouse, P < 0.01 at 24h). Further analysis in the experimental mouse model revealed that CD11b+ myeloid cells, with significant increase in their population (P < 0.01), had high level of CD39 (88.80 ± 2.05 %) and increased expression of CD73 (P < 0.05). CD19+ B lymphocytes showed slight increases of CD39 (P < 0.05 at 2h) and CD73 (P < 0.05 at 2h), while, CD3+ T lymphocytes had decreased levels of them. These findings suggested a distinct patterns of expression of CD39 and CD73 in these specific immune cell populations after CA.

Conclusions

These data have provided comprehensive insights into the immune response after CA, highlighting high-level expressions of CD39 and CD73 in myeloid cells.

Antibiotic Prophylaxis in Patients On Extracorporeal Membrane Oxygenation: A Systematic Review

Despite the frequent use of prophylactic antibiotics in hospitals for extracorporeal membrane oxygenation (ECMO) patients, the Extracorporeal Life Support Organization (ELSO) Infectious Disease Task Force does not recommend routine antibiotic prophylaxis due to a lack of compelling evidence. We assessed the effectiveness of prophylactic antibiotics in ECMO patients. We conducted a comprehensive search of multiple databases from their inception up to September 6, 2023, on various databases using keywords like "antibiotics," "prophylaxis," "extracorporeal membrane oxygenation," and "ECMO." Newcastle-Ottawa Scale (NOS) was used to assess the quality of the included research. We collected data using Microsoft Excel version 2016, mean and standard deviations were calculated for continuous data, while frequencies and percentages were calculated for binomial data. A total of three studies was included in the review with a total of 8,954 participants, of which 4,483 (50.06%) received antibiotic prophylaxis, and 1,131 (25.22%) were female. The administration of antibiotics prophylactically was associated with reduction in rate of mortality, the risk of infections, and complications like acute kidney injury and diarrhea. Although there have been some benefits on antibiotic prophylaxis, prospective research, and possibly the creation of tailored, ECMO-specific bundles will be needed to identify efficient ways to prevent ECMO infection.

Critical Care Management of Patients After Cardiac Arrest: A Scientific Statement from the American Heart Association and Neurocritical Care Society

The critical care management of patients after cardiac arrest is burdened by a lack of high-quality clinical studies and the resultant lack of high-certainty evidence. This results in limited practice guideline recommendations, which may lead to uncertainty and variability in management. Critical care management is crucial in patients after cardiac arrest and affects outcome. Although guidelines address some relevant topics (including temperature control and neurological prognostication of comatose survivors, 2 topics for which there are more robust clinical studies), many important subject areas have limited or nonexistent clinical studies, leading to the absence of guidelines or low-certainty evidence. The American Heart Association Emergency Cardiovascular Care Committee and the Neurocritical Care Society collaborated to address this gap by organizing an expert consensus panel and conference. Twenty-four experienced practitioners (including physicians, nurses, pharmacists, and a respiratory therapist) from multiple medical specialties, levels, institutions, and countries made up the panel. Topics were identified and prioritized by the panel and arranged by organ system to facilitate discussion, debate, and consensus building. Statements related to postarrest management were generated, and 80% agreement was required to approve a statement. Voting was anonymous and web based. Topics addressed include neurological, cardiac, pulmonary, hematological, infectious, gastrointestinal, endocrine, and general critical care management. Areas of uncertainty, areas for which no consensus was reached, and future research directions are also included. Until high-quality studies that inform practice guidelines in these areas are available, the expert panel consensus statements that are provided can advise clinicians on the critical care management of patients after cardiac arrest.

Critical Care Management of Patients After Cardiac Arrest: A Scientific Statement From the American Heart Association and Neurocritical Care Society

The critical care management of patients after cardiac arrest is burdened by a lack of high-quality clinical studies and the resultant lack of high-certainty evidence. This results in limited practice guideline recommendations, which may lead to uncertainty and variability in management. Critical care management is crucial in patients after cardiac arrest and affects outcome. Although guidelines address some relevant topics (including temperature control and neurological prognostication of comatose survivors, 2 topics for which there are more robust clinical studies), many important subject areas have limited or nonexistent clinical studies, leading to the absence of guidelines or low-certainty evidence. The American Heart Association Emergency Cardiovascular Care Committee and the Neurocritical Care Society collaborated to address this gap by organizing an expert consensus panel and conference. Twenty-four experienced practitioners (including physicians, nurses, pharmacists, and a respiratory therapist) from multiple medical specialties, levels, institutions, and countries made up the panel. Topics were identified and prioritized by the panel and arranged by organ system to facilitate discussion, debate, and consensus building. Statements related to postarrest management were generated, and 80% agreement was required to approve a statement. Voting was anonymous and web based. Topics addressed include neurological, cardiac, pulmonary, hematological, infectious, gastrointestinal, endocrine, and general critical care management. Areas of uncertainty, areas for which no consensus was reached, and future research directions are also included. Until high-quality studies that inform practice guidelines in these areas are available, the expert panel consensus statements that are provided can advise clinicians on the critical care management of patients after cardiac arrest.

Intestinal injury in cardiac arrest is associated with multiple organ dysfunction: A prospective cohort study

BACKGROUND

The impact of intestinal injury in cardiac arrest is not established. The first aim of this study was to assess associations between clinical characteristics in out-of-hospital cardiac arrest (OHCA) and a biomarker for intestinal injury, Intestinal Fatty Acid Binding Protein (IFABP). The second aim was to assess associations between IFABP and multiple organ dysfunction and 30-day mortality.

METHODS

We measured plasma IFABP in 50 patients at admission to intensive care unit (ICU) after OHCA. Demographic and clinical variables were analysed by stratifying patients on median IFABP, and by linear regression. We compared Sequential Organ Failure Assessment (SOFA) score, haemodynamic variables, and clinical-chemistry tests at day two between the "high" and "low" IFABP groups. Logistic regression was applied to assess factors associated with 30-day mortality.

RESULTS

Several markers of whole body ischaemia correlated with intestinal injury. Duration of arrest and lactate serum concentrations contributed to elevated IFABP in a multivariable model (p < 0.01 and p = 0.04, respectively). At day two, all seven patients who had died were in the "high" IFABP group, and all six patients who had been transferred to ward were in the "low" group. Of patients still treated in the ICU, the "high" group had higher total, renal and respiratory SOFA score (p < 0.01) and included all patients receiving inotropic drugs. IFABP predicted mortality (OR 16.9 per standard deviation increase, p = 0.04).

CONCLUSION

Cardiac arrest duration and lactate serum concentrations were risk factors for intestinal injury. High levels of IFABP at admission were associated with multiple organ dysfunction and mortality.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02648061.

Asphyxia-Induced Bacterial Translocation in an Animal Experimental Model in Neonatal Piglets

BACKGROUND

The term "bacterial translocation" (BT) refers to the migration of bacteria or their products from the gastrointestinal tract to tissues located outside it, and may occur after intestinal ischemia-reperfusion injury. The term "endotoxin" is synonymous, and is used interchangeably with the term lipopolysaccharide (LPS). LPS, a component of Gram-negative gut bacteria, is a potent microbial virulence factor, that can trigger production of pro-inflammatory mediators, causing localized and systemic inflammation. The aim of this study is to investigate if neonatal asphyxia provokes BT and an increased concentration of LPS in an animal model of asphyxia in piglets.

METHODS

Twenty-one (21) newborn male Landrace/Large White piglets, 1-4 days old, were randomly allocated into three groups, Control (A), Asphyxia (B) and Asphyxia-Cardiopulmonary Resuscitation (CPR) (C). All animals were instrumented, anesthetized and underwent hemodynamic monitoring. In Group A, the animals were euthanized. In Group B, the endotracheal tube was occluded to cause asphyxia leading to cardiopulmonary arrest. In Group C, the animals were resuscitated after asphyxia and further monitored for 30'. Bacterial translocation was assessed by the measurement of endotoxin in blood from the portal vein and the aorta, and also by the measurement of endotoxin in mesenteric lymph nodes (MLNs) at euthanasia. The results are given as median (IQR) with LPS concentration in EU/mL.

RESULTS

BT was observed in all groups with minimum LPS concentration in the MLN and maximum concentration in the portal vein. LPS levels in the MLNs were higher in the Group B: 6.38 EU/mL (2.69-9.34) compared to the other groups (Group A: 2.1 EU/mL (1.08-2.52), Group C: 1.66 EU/mL (1.51-2.48), p = 0.012). The aorta to MLNs LPS difference (%) was lower in Group B: 0.13% (0.04-1.17), compared to Group A: 5.08% (2.2-10.7), and Group C: 3.42% (1.5-5.1)) (p = 0.042). The same was detected for portal to MLNs LPS difference (%) which was lower in Group B: 0.94% (0.5-3) compared to Group A: 4.9% (4-15), and Group C: 3.85% (1.5-5.1)) (p = 0.044).

CONCLUSIONS

Neonatal asphyxia can provoke ΒΤ and increased LPS concentration in blood and tissue located outside the gastrointestinal system.

Ischemic injury of the upper gastrointestinal tract after out-of-hospital cardiac arrest: a prospective, multicenter study

Background

The consequences of cardiac arrest (CA) on the gastro-intestinal tract are poorly understood. We measured the incidence of ischemic injury in the upper gastro-intestinal tract after Out-of-hospital CA (OHCA) and determined the risk factors for and consequences of gastrointestinal ischemic injury according to its severity.

Methods

Prospective, non-controlled, multicenter study in nine ICUs in France and Belgium conducted from November 1, 2014 to November 30, 2018. Included patients underwent an esophago-gastro-duodenoscopy 2 to 4 d after OHCA if still intubated and the presence of ischemic lesions of the upper gastro-intestinal tract was determined by a gastroenterologist. Lesions were a priori defined as severe if there was ulceration or necrosis and moderate if there was mucosal edema or erythema. We compared clinical and cardiac arrest characteristics of three groups of patients (no, moderate, and severe lesions) and identified variables associated with gastrointestinal ischemic injury using multivariate regression analysis. We also compared the outcomes (organ failure during ICU stay and neurological status at hospital discharge) of the three groups of patients.

Results

Among the 214 patients included in the analysis, 121 (57%, 95% CI 50–63%) had an upper gastrointestinal ischemic lesion, most frequently on the fundus. Ischemic lesions were severe in 55/121 (45%) patients. In multivariate regression, higher adrenaline dose during cardiopulmonary resuscitation (OR 1.25 per mg (1.08–1.46)) was independently associated with increased odds of severe upper gastrointestinal ischemic lesions; previous proton pump inhibitor use (OR 0.40 (0.14–1.00)) and serum bicarbonate on day 1 (OR 0.89 (0.81–0.97)) were associated with lower odds of ischemic lesions. Patients with severe lesions had a higher SOFA score during the ICU stay and worse neurological outcome at hospital discharge.

Conclusions

More than half of the patients successfully resuscitated from OHCA had upper gastrointestinal tract ischemic injury. Presence of ischemic lesions was independently associated with the amount of adrenaline used during resuscitation. Patients with severe lesions had higher organ failure scores during the ICU stay and a worse prognosis.

Clinical Trial RegistrationNCT02349074.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03939-9.

Ceftriaxone to PRevent pneumOnia and inflammaTion aftEr Cardiac arresT (PROTECT): study protocol for a randomized, placebo-controlled trial

BACKGROUND

Pneumonia is the most common infection after out-of-hospital cardiac arrest (OHCA) occurring in up to 65% of patients who remain comatose after return of spontaneous circulation. Preventing infection after OHCA may (1) reduce exposure to broad-spectrum antibiotics, (2) prevent hemodynamic derangements due to local and systemic inflammation, and (3) prevent infection-associated morbidity and mortality.

METHODS

The ceftriaxone to PRevent pneumOnia and inflammaTion aftEr Cardiac arrest (PROTECT) trial is a randomized, placebo-controlled, single-center, quadruple-blind (patient, treatment team, research team, outcome assessors), non-commercial, superiority trial to be conducted at Maine Medical Center in Portland, Maine, USA. Ceftriaxone 2 g intravenously every 12 h for 3 days will be compared with matching placebo. The primary efficacy outcome is incidence of early-onset pneumonia occurring < 4 days after mechanical ventilation initiation. Concurrently, T cell-mediated inflammation bacterial resistomes will be examined. Safety outcomes include incidence of type-one immediate-type hypersensitivity reactions, gallbladder injury, and Clostridioides difficile-associated diarrhea. The trial will enroll 120 subjects over approximately 3 to 4 years.

DISCUSSION

The PROTECT trial is novel in its (1) inclusion of OHCA survivors regardless of initial heart rhythm, (2) use of a low-risk antibiotic available in the USA that has not previously been tested after OHCA, (3) inclusion of anti-inflammatory effects of ceftriaxone as a novel mechanism for improved clinical outcomes, and (4) complete metagenomic assessment of bacterial resistomes pre- and post-ceftriaxone prophylaxis. The long-term goal is to develop a definitive phase III trial powered for mortality or functional outcome.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04999592 . Registered on August 10, 2021.

The incidence and characteristics of bacteremia in cardiac arrest

BACKGROUND

Despite improvements in both preventative and post-event care, cardiac arrest still occurs frequently with high morbidity and mortality. Bacteremia is a potential cause or complication of cardiac arrest that has received increasing notoriety in recent years.

OBJECTIVES

To identify the incidence of and predictive factors for bacteremia in both inside and outside of hospital cardiac arrest patients.

METHODS

Retrospective, single centered, cohort study conducted at an academic medical center. Patients 18 years of age or older with cardiac arrest and blood cultures drawn within 24 h of the event were included.

RESULTS

Two-hundred sixty-three cardiac arrest patients were included, of which forty-three patients (16.3%) were bacteremic. Patients with bacteremia had higher rates of home parenteral nutrition and a history of known infection before cardiac arrest. Bacteremic patients had a higher blood urea nitrogen (30 mg/dL vs. 23, p = 0.02), serum creatinine (2.40 mg/dL  vs. 1.70, p = 0.05), and troponin (0.39 ng/mL vs. 0.12, p = 0.03) compared with the non-bacteremic group. There were no differences in duration of mechanical ventilation, hospital length of stay or ICU length of stay. Mortality at 28-days was higher in the bacteremic group (79%) compared to the non-bacteremic group (60.9%, p = 0.02). No factors associated with bacteremia were identified.

CONCLUSION

Bacteremia was observed in 16.3% of patients, with significant differences between the bacteremic and non-bacteremic group regarding home parenteral nutrition and known infection before the event, cardiac arrest characteristics (blood urea nitrogen, serum creatinine, and troponin), and 28-day mortality.

Post-Cardiac Arrest Syndrome Is Not Associated with An Early Bacterial Translocation

BACKGROUND

The aim of this study was to investigate bacterial translocation and its possible role in the development of post-resuscitation inflammatory response following Cardio-Pulmonary Resuscitation (CPR) after cardiac arrest.

METHODS

Munich female swine were employed for a model of cardiac arrest via application of electrical current. After 7 min, CPR was initiated, and animals were either successfully return to spontaneous circulation (ROSC) within 40 min or not (no-ROSC). At the end of experimental period and prior to sacrifice, samples from the intestine, mesenteric lymph nodes (MLN), liver and portal vein blood were obtained. Evaluation of inflammation and gut permeability was performed; MLN, liver and portal vein samples were analyzed for 16 s rRNA detection and cytokine mRNA expression.

RESULTS

A decreased expression of the tight junction protein Occludin, with higher levels of inflammation, greater epithelial disintegration, ulceration, loss of crypts and villi height were found in the intestines of the ROSC swine in comparison to no-ROSC. The macrophage surface antigen CD-14 staining was relatively more intense in the ROSC than in no-ROSC. Higher levels of TNF-α mRNA expression were present in the liver of the ROSC group. Finally, despite the inflammatory response and the gut mucosal alterations in ROSC group, no bacterial translocation was detected in liver, MLN and portal vein.

CONCLUSIONS

We show that resuscitation from cardiac arrest induces inflammatory response and intestinal permeability in swine 4h after resuscitation, but not a bacterial translocation. Bacterial translocation is not an early phase phenomenon but probably part of the pathophysiologic sequelae.

The association of early diarrhea after successful resuscitation following out-of-hospital cardiac arrest with neurological outcome: A retrospective observational study

Gastrointestinal ischemia with reperfusion tissue injury contributes to post-cardiac arrest syndrome. We hypothesized that diarrhea is a symptom of intestinal ischemia/reperfusion injury and investigated whether the occurrence of early diarrhea (≤12 hours) after successful cardiopulmonary resuscitation is associated with an unfavorable neurological outcome.We analyzed data from the Vienna Clinical Cardiac Arrest Registry. Inclusion criteria comprised ≥18 years of age, a witnessed, non-traumatic out-of-hospital cardiac arrest, return of spontaneous circulation (ROSC), initial shockable rhythm, and ST-segment elevation in electrocardiogram after ROSC with consecutive coronary angiography. Patients with diarrhea caused by other factors (e.g., infections, antibiotic treatment, or chronic diseases) were excluded. The primary endpoint was neurological function between patients with or without "early diarrhea" (≤12 hours after ROSC) according to cerebral performance categories.We included 156 patients between 2005 and 2012. The rate of unfavorable neurologic outcome was higher in patients with early diarrhea (67% vs 37%). In univariate analysis, the crude odds ratio for unfavorable neurologic outcome was 3.42 (95% confidence interval, 1.11-10.56, P = .03) for early diarrhea. After multivariate adjustment for traditional prognostication markers the odds ratio of early diarrhea was 5.90 (95% confidence interval, 1.28-27.06, P = .02).In conclusion, early diarrhea within 12 hours after successful cardiopulmonary resuscitation was associated with an unfavorable neurological outcome.

Effects of 9-t-butyl doxycycline on the innate immune response to CNS ischemia-reperfusion injury

Cerebral ischemia triggers a cascade of neuroinflammatory and peripheral immune responses that contribute to post-ischemic reperfusion injury. Prior work conducted in CNS ischemia models underscore the potential to harness non-antibiotic properties of tetracycline antibiotics for therapeutic benefit. In the present study, we explored the immunomodulatory effects of the tetracycline derivative 9-tert-butyl doxycycline (9-TB) in a mouse model of transient global ischemia that mimics immunologic aspects of the post-cardiac arrest syndrome. Pharmacokinetic studies performed in C57BL/6 mice demonstrate that within four hours after delivery, levels of 9-TB in the brain were 1.6 and 9.5-fold higher than those obtained using minocycline and doxycycline, respectively. Minocycline and 9-TB also dampened inflammation, measured by reduced TNFα-inducible, NF-κβ-dependent luciferase activity in a microglial reporter line. Notably, daily 9-TB treatment following ischemia-reperfusion injury in vivo induced the retention of polymorphonuclear neutrophils (PMNs) within the spleen while simultaneously biasing CNS PMNs towards an anti-inflammatory (CD11b^LowYm1+) phenotype. These studies indicate that aside from exhibiting enhanced CNS delivery, 9-TB alters both the trafficking and polarization of PMNs in the context of CNS ischemia-reperfusion injury.

Post-resuscitation shock: recent advances in pathophysiology and treatment

A post-resuscitation shock occurs in 50–70% of patients who had a cardiac arrest. It is an early and transient complication of the post-resuscitation phase, which frequently leads to multiple-organ failure and high mortality. The pathophysiology of post-resuscitation shock is complex and results from the whole-body ischemia–reperfusion process provoked by the sequence of circulatory arrest, resuscitation manoeuvers and return of spontaneous circulation, combining a myocardial dysfunction and sepsis features, such as vasoplegia, hypovolemia and endothelial dysfunction. Similarly to septic shock, the hemodynamic management of post-resuscitation shock is based on an early and aggressive hemodynamic management, including fluid administration, vasopressors and/or inotropes. Norepinephrine should be considered as the first-line vasopressor in order to avoid arrhythmogenic effects of other catecholamines and dobutamine is the most established inotrope in this situation. Importantly, the optimal mean arterial pressure target during the post-resuscitation shock still remains unknown and may probably vary according to patients. Mechanical circulatory support by extracorporeal membrane oxygenation can be necessary in the most severe patients, when the neurological prognosis is assumed to be favourable. Other symptomatic treatments include protective lung ventilation with a target of normoxia and normocapnia and targeted temperature management by avoiding the lowest temperature targets. Early coronary angiogram and coronary reperfusion must be considered in ST-elevation myocardial infarction (STEMI) patients with preserved neurological prognosis although the timing of coronary angiogram in non-STEMI patients is still a matter of debate. Further clinical research is needed in order to explore new therapeutic opportunities regarding inflammatory, hormonal and vascular dysfunction.

Frequency, risk factors, and outcomes of non-occlusive mesenteric ischaemia after cardiac arrest

PURPOSE

Mesenteric ischaemia after successfully resuscitated cardiac arrest (CA) has been insufficiently studied. We aimed to assess the frequency, risk factors, and outcomes of non-occlusive mesenteric ischaemia (NOMI) after CA.

METHODS

We retrospectively included patients admitted to a CA centre with sustained return of spontaneous circulation between 2007 and 2017. NOMI was suspected based on clinical symptoms and classified as possible if no tests were feasible or the only test was a negative abdominal computed tomography (CT) scan and as confirmed if diagnosed by endoscopy, CT, or surgery.

RESULTS

Of 1343 patients, 82 (6%) had suspected NOMI, including 33 (2.5%) with confirmed NOMI. Investigations for suspected NOMI were done in 47/82 (57%) patients (CT, n = 30; lower digestive endoscopy, n = 14; and upper digestive endoscopy, n = 12); 11 patients underwent surgery. By multivariate analysis, factors associated with suspected NOMI were female sex (OR, 1.8; 95%CI, 1.1-2.9, p = 0.02), cardiovascular comorbidities (OR, 1.6; 95%CI, 1.0-2.7; p = 0.047), admission lactate >5 mmol/L (OR, 2.0; 95%CI, 1.2-3.4; p = 0.01), low flow >17 min (OR, 2.2; 95%CI, 1.3-3.8; p = 0.003), and inotropic score >7 μg/kg/min (OR, 1.8; 95%CI, 1.1-3.2; p = 0.03). ICU mortality was 96% (79/82), with 61% of patients dying from multi-organ failure (MOF) and 35% from post-anoxic brain injury. Of the eight patients who regained consciousness, 5 finally died from MOF, leaving 3 patients discharged alive from the ICU with a good neurologic outcome.

CONCLUSIONS

NOMI may affect 2.5-6% of patients after CA. Mortality was extremely high in patients, and very few survived with a good neurological outcome.

Assessment of Post-Resuscitation Intestinal Injury and Timing of Bacterial Translocation in Swine Anaesthetized With Propofol-Based Total Intravenous Anaesthesia

Introduction and objectives Bacterial translocation (BT) is the passage of viable bacteria or endotoxins from the gastrointestinal lumen to extra-luminal tissues and is usually observed after intestinal ischaemia-reperfusion injury. The aim of this study was to investigate post-resuscitation BT after cardiac arrest and resuscitation in a swine anaesthetized with propofol-based total intravenous anaesthesia. Materials and methods Eighteen female Landrace/Large White piglets were randomly divided into control (CON), cardiac arrest (CA) and cardiac arrest-cardiopulmonary resuscitation (CA-CPR) groups. In the CON group, the animals were only monitored for two hours. In the CA group, the animals were not resuscitated and underwent necropsy immediately after cardiac arrest. In the CA-CPR group, the animals were resuscitated until the return of spontaneous circulation (ROSC) and were monitored for two hours. The animals of the CON and CA-CPR groups underwent necropsy 24 hours later. Bacterial translocation was assessed by blood and tissue cultures and endotoxin measurement in the portal and systemic circulation. Malondialdehyde content calculation and histological analysis of the intestine were performed in order to estimate ischemia and reperfusion (I/R) tissue damage. Results  Malondialdehyde content, an indicator of oxidative stress, was significantly higher in the CA-CPR group compared to the CA in homogenized ileum (p=0.016). Malondialdehyde content in homogenized colon revealed significantly higher levels in the CA-CPR group compared to the CON (p=0.004) and the CA group (p=0.016). We found significantly higher levels of portal endotoxin in the CA-CPR group compared to the CON (p=0.026) and the CA group (p=0.026). The number of positive mesenteric lymph nodes cultures for E. coli was greater in the CA-CPR group, followed by the CA and CON groups, although the difference was not significant (67%, 33%, and 33%, respectively; p=0.407). Conclusions Malondialdehyde content and portal endotoxin levels do not increase during the cardiac arrest interval, but only after CPR and ROSC. Although the number of positive MLNs cultures was greater in the CA-CPR animals, no statistically significant differences were observed between the three groups due to the short monitoring period.

Low PCSK-9 levels Are Associated with Favorable Neurologic Function after Resuscitation from out of Hospital Cardiac Arrest

Endotoxemia after cardiopulmonary resuscitation (CPR) is associated with unfavorable outcome. Proprotein convertase subtilisin/kexin type-9 (PCSK–9) regulates low-density lipoprotein receptors, which mediate the hepatic uptake of endotoxins. We hypothesized that PCSK–9 concentrations are associated with neurological outcome in patients after CPR. Successfully resuscitated out-of-hospital cardiac arrest patients were included prospectively (n = 79). PCSK–9 levels were measured on admission, 12 h and 24 h thereafter, and after rewarming. The primary outcome was favorable neurologic function at day 30, defined by cerebral performance categories (CPC 1–2 = favorable vs. CPC 3–5 = unfavorable). Receiver operating characteristic curve analysis was used to identify the PCSK–9 level cut-off for optimal discrimination between favorable and unfavorable 30-day neurologic function. Logistic regression models were calculated to estimate the effect of PCSK–9 levels on the primary outcome, given as odds ratio (OR) and 95% confidence interval (95%CI). PCSK–9 levels on admission were significantly lower in patients with favorable 30-day neurologic function (median 158 ng/mL, (quartiles: 124–225) vs. 207 ng/mL (174–259); p = 0.019). The optimally discriminating PCSK–9 level cut-off was 165 ng/mL. In patients with PCSK–9 levels ≥ 165 ng/mL, the odds of unfavorable neurological outcome were 4.7-fold higher compared to those with PCSK–9 levels < 165 ng/mL. In conclusion, low PCSK–9 levels were associated with favorable neurologic function.

Lung-Derived SOD3 Attenuates Neurovascular Injury After Transient Global Cerebral Ischemia

Background

Systemic innate immune priming is a recognized sequela of post‐ischemic neuroinflammation and contributor to delayed neurodegeneration. Given mounting evidence linking acute stroke with reactive lung inflammation, we asked whether enhanced expression of the endogenous antioxidant extracellular superoxide dismutase 3 (SOD3) produced by alveolar type II pneumocytes would protect the lung from transient global cerebral ischemia and the brain from the delayed effects of ischemia‐reperfusion.

Methods and Results

Following 15 minutes of global cerebral ischemia or sham conditions, transgenic SOD3 and wild‐type mice were followed daily for changes in weight, core temperature, and neurological function. Three days after reperfusion, arterial and venous samples were collected for complete blood counts, flow cytometry, and SOD3 protein blotting, and immunohistochemistry was performed on lung and brain tissue to assess tissue injury, blood‐brain barrier permeability, and neutrophil transmigration. Relative to ischemic controls, transgenic SOD3 mice performed better on functional testing and exhibited reduced peripheral neutrophil activation, lung inflammation, and blood‐brain barrier leak. Once released from the lung, SOD3 was predominantly not cell associated and depleted in the venous phase of circulation.

Conclusions

In addition to reducing the local inflammatory response to cerebral ischemia, targeted enrichment of SOD3 within the lung confers distal neuroprotection against ischemia‐reperfusion injury. These data suggest that therapies geared toward enhancing adaptive lung‐neurovascular coupling may improve outcomes following acute stroke and cardiac arrest.

Characterization of neutrophil-neuronal co-cultures to investigate mechanisms of post-ischemic immune-mediated neurotoxicity

BACKGROUND

Immune-mediated reperfusion injury is a critical component of post-ischemic central nervous system (CNS) damage. In this context, the activation and recruitment of polymorphonuclear neutrophils (PMNs) to the CNS induces neurotoxicity in part through the release of degradative enzymes, cytokines, and reactive oxygen species. However, the extent to which close-range interactions between PMNs and neurons contribute to injury in this context has not been directly investigated.

NEW METHOD

We devised a co-culture model to investigate mechanisms of PMN-dependent neurotoxicity. Specifically, we established the effect of PMN dose, co-incident neuronal ischemia, lipopolysaccharide (LPS)-induced PMN priming, and the requirement for cell-cell contact on cumulative neuron damage.

RESULTS AND COMPARISON TO EXISTING METHOD(S)

Pre-exposure of day in vitro 10 primary cortical neurons to oxygen-glucose deprivation (OGD) enhanced PMN-dependent neuronal death. Likewise, LPS-induced priming of the PMN donor further increased PMN-induced toxicity in vitro compared to saline-injected controls. Compartmentalization of LPS-primed PMNs using net wells confirmed the requirement for close-range cell-cell interactions in the process of PMN-induced neuronal injury. Moreover, time-lapse imaging and quantitative neurite analyses implicate PMN-neurite interactions in this pathological response. These experiments establish a platform to investigate immune and neural factors that contribute to post-ischemic neurodegeneration.

CONCLUSIONS

Ischemic and immune priming enhance neurotoxicity in PMN-neuronal co-cultures. Moreover, cell-cell contact and neurite destruction are prominent features in the observed mechanism of post-ischemic neuronal death.

Lung SOD3 limits neurovascular reperfusion injury and systemic immune activation following transient global cerebral ischemia

BACKGROUND AND OBJECTIVES

Studies implicate the lung in moderating systemic immune activation via effects on circulating leukocytes. In this study, we investigated whether targeted expression of the antioxidant extracellular superoxide dismutase (SOD3) within the lung would influence post-ischemic peripheral neutrophil activation and CNS reperfusion injury.

METHODS

Adult, male mice expressing human SOD3 within type II pneumocytes were subjected to 15 min of transient global cerebral ischemia. Three days post-reperfusion, lung and brain tissue was collected and analyzed by immunohistochemistry for inflammation and injury markers. In vitro motility and neurotoxicity assays were conducted to ascertain the direct effects of hSOD3 on PMN activation. Results were compared against C57BL/6 age and sex-matched controls.

RESULTS

Relative to wild-type controls, hSOD3 heterozygous mice exhibited a reduction in lung inflammation, blood-brain barrier damage, and post-ischemic neuronal injury within the hippocampus and cortex. PMNs harvested from hSOD3 mice were also resistant to LPS priming, slower-moving, and less toxic to primary neuronal cultures.

CONCLUSIONS

Constitutive, focal expression of hSOD3 is neuroprotective in a model of global cerebral ischemia-reperfusion injury. The underlying mechanism of SOD3-dependent protection is attributable in part to effects on the activation state and toxic potential of circulating neutrophils. These results implicate lung-brain coupling as a determinant of cerebral ischemia-reperfusion injury and highlight post-stroke lung inflammation as a potential therapeutic target in acute ischemic cerebrovascular injuries.

Postresuscitation Care after Out-of-hospital Cardiac Arrest: Clinical Update and Focus on Targeted Temperature Management

Out-of-hospital cardiac arrest is a major cause of mortality and morbidity worldwide. With the introduction of targeted temperature management more than a decade ago, postresuscitation care has attracted increased attention. In the present review, we discuss best practice hospital management of unconscious out-of-hospital cardiac arrest patients with a special focus on targeted temperature management. What is termed post-cardiac arrest syndrome strikes all organs and mandates access to specialized intensive care. All patients need a secured airway, and most patients need hemodynamic support with fluids and/or vasopressors. Furthermore, immediate coronary angiography and percutaneous coronary intervention, when indicated, has become an essential part of the postresuscitation treatment. Targeted temperature management with controlled sedation and mechanical ventilation is the most important neuroprotective strategy to take. Targeted temperature management should be initiated as quickly as possible, and according to international guidelines, it should be maintained at 32° to 36°C for at least 24 h, whereas rewarming should not increase more than 0.5°C per hour. However, uncertainty remains regarding targeted temperature management components, warranting further research into the optimal cooling rate, target temperature, duration of cooling, and the rewarming rate. Moreover, targeted temperature management is linked to some adverse effects. The risk of infection and bleeding is moderately increased, as is the risk of hypokalemia and magnesemia. Circulation needs to be monitored invasively and any deviances corrected in a timely fashion. Outcome prediction in the individual patient is challenging, and a self-fulfilling prophecy poses a real threat to early prognostication based on clinical assessment alone. Therefore, delayed and multimodal prognostication is now considered a key element of postresuscitation care. Finally, modern postresuscitation care can produce good outcomes in the majority of patients but requires major diagnostic and therapeutic resources and specific training. Hence, recent international guidelines strongly recommend the implementation of regional prehospital resuscitation systems with integrated and specialized cardiac arrest centers.

Initial serum cholesterol level as a potential marker for post cardiac arrest patient outcomes

AIM

Cholesterol and lipoproteins have many roles during systemic inflammation in critically ill patients. Many previous studies have reported that low levels of cholesterol are associated with poor outcomes in these patients. The aim of this study was to investigate the association of initial total cholesterol with predicting neurologic outcome of post-cardiac arrest patients.

METHODS

This was a retrospective observational study of out-of-hospital-cardiac arrest (OHCA) survivors who had serum cholesterol levels at admission. Multivariate regression analysis was performed to investigate total cholesterol and its association with neurologic outcome. Area under receiver operator characteristic curve (AUROC) was assessed and cut off values for predicting good or poor neurologic outcomes were analysed.

RESULTS

A total of 355 patients were analysed. Lower total cholesterol was significantly associated with poor neurologic outcome [OR: 0.99 (95% CI: 0.98-0.99), p < 0.01] in the multivariate analysis. Cholesterol was also useful to screening for poor neurologic outcome [AUROC: 0.70 (95%CI: 0.63-0.77)]. Patients with cholesterol lower than 71 mg/dL had poor neurologic outcome with a specificity of 100%.

CONCLUSIONS

Initial cholesterol level is an easily obtained biomarker that showed association with neurologic outcomes of post cardiac arrest patients.

Early Changes in Circulatory T Helper Type 1, 2, and 17 Cells of Patients with Out-of-Hospital Cardiac Arrest after Successful Cardiopulmonary Resuscitation

Background

Immune disorder is an important feature of patients with out-of-hospital cardiac arrest (OHCA) after the return of spontaneous circulation (ROSC). We investigated the expression of circulatory T helper type (Th) 1, Th2, and Th17 cells to explore the early immune alteration in OHCA patients after ROSC.

Methods

During July-September 2016 and March-September 2017, 65 consecutive OHCA patients with ROSC >12 h and 30 healthy individuals were enrolled in this study. Clinical and 28-day survival data were collected. Peripheral blood samples were analyzed to evaluate the expression of Th1/Th2/Th17 cells by flow cytometry from OHCA patients after ROSC on days 1 and 3 and from healthy individuals.

Results

Compared with healthy individuals, T lymphocyte counts and Th1 cell counts decreased on days 1 and 3 after ROSC (1464 [1198, 2152] vs. 779 [481, 1140] vs. 581 [324, 1118]/μl, χ² = 30.342, P < 0.001; 154 [90, 246] vs. 39 [19, 78] vs. 24 [12, 53]/μl, χ² = 42.880, P < 0.001), and Th2 and Th17 cell counts decreased on day 3 (17.0 [10.8, 24.0] vs. 9.0 [3.0, 15.5]/μl, Z = -3.228, P = 0.001; 4.7 [2.7, 9.1] vs. 2.7 [1.0, 6.5]/μl, Z = -2.294, P = 0.022). No change in CD4+/CD3+ lymphocyte ratio was seen on day 1 or day 3 (57.9 [49.4, 63.0] vs. 55.4 [46.5, 66.5] vs. 55.4 [50.2, 67.0]%, χ² = 0.171, P = 0.918). Th1/CD4+ lymphocyte ratio decreased on days 1 and 3 (19.0 [14.0, 24.9] vs. 9.3 [4.6, 13.9] vs. 9.5 [4.9, 13.6]%, χ² = 25.754, P < 0.001), and Th2/CD4+ lymphocyte ratio increased on day 1 and decreased on day 3 (1.9 [1.2, 2.5] vs. 2.5 [1.6, 4.0] vs. 1.9 [1.6, 3.8]%, χ² = 6.913, P = 0.032). Th1/Th2 cell ratio also decreased on both days (9.4 [7.3, 13.5] vs. 3.1 [1.9, 5.6] vs. 4.2 [2.8, 5.9], χ² = 44.262, P < 0.001). Despite an upward trend in the median of Th17/CD4+ lymphocyte ratio in OHCA patients, there was no significant difference compared with healthy individuals (0.9 [0.4, 1.2] vs. 0.7 [0.4, 1.2] vs. 0.6 [0.3, 1.0]%, χ² = 2.620, P = 0.270). The dynamic expression of Th1/Th2/Th17 cells on days 1 and 3 were simultaneously analyzed in 28/53 OHCA patients who survived >3 days; patients were divided into survivors (n = 10) and nonsurvivors (n = 18) based on 28-day survival. No significant differences in Th1/Th2/Th17 cell counts, ratios in CD4+ lymphocytes, and Th1/Th2 cell ratio were seen between survivors and nonsurvivors on both days (all P > 0.05). There was no difference over time in both survivors and nonsurvivors (all P > 0.05).

Conclusion

Downregulated T lymphocyte counts, including Th1/Th2/Th17 subsets and Th1/Th2 cell ratio imbalance, occur in the early period after ROSC, that may be involved in immune dysfunction in OHCA patients.

Overexpression of programmed cell death-1 and human leucocyte antigen-DR on circulatory regulatory T cells in out-of-hospital cardiac arrest patients in the early period after return of spontaneous circulation

AIM

Whether regulatory T cells (Tregs) are involved in immune disorders of out-of-hospital cardiac arrest (OHCA) patients after return of spontaneous circulation (ROSC) is still unknown. We aimed to observe the expression of circulatory Tregs in OHCA patients and investigate programmed cell death-1 (PD-1) and human leucocyte antigen-DR (HLA-DR) on Tregs to evaluate the induction and activity of Tregs.

METHODS

Sixty-seven consecutive OHCA patients who recovered from spontaneous circulation over 12 h were enrolled. Clinical and 28-day outcome data were collected. Peripheral blood samples collected on days 1 and 3 after ROSC were analysed to evaluate PD-1 and HLA-DR expression on Tregs. Fifty healthy individuals were enrolled as healthy controls.

RESULTS

Compared with those in healthy individuals, circulatory Treg counts significantly decreased without changes of Treg/cluster-of-differentiation (CD)4+ lymphocyte ratios on day 1 after ROSC, and the percentage of PD-1+ Tregs and HLA-DR+ Tregs significantly rose. On day 3, Treg/CD4+ lymphocyte ratios rose with persistently low Treg counts, and the expression of PD-1 and HLA-DR on Tregs was not different from that on day 1. On day 1, both circulatory Treg counts and Treg/CD4+ lymphocyte ratios in non-survivors were lower than those in survivors, and Treg/CD4+ lymphocyte ratios increased in non-survivors on day 3. No significant difference of PD-1 and HLA-DR expression on Tregs was found between survivors and non-survivors on day 1.

CONCLUSIONS

After ROSC, despite decreased circulatory Treg counts, a relative increase of Treg percentage and enhanced activity of Tregs are involved in early immune regulation of OHCA patients.

Admission levels of high-density lipoprotein and apolipoprotein A-1 are associated with the neurologic outcome in patients with out-of-hospital cardiac arrest

Objective

To investigate whether serum levels of high-density lipoprotein (HDL) and apolipoprotein A-1 (ApoA1), after the return of spontaneous circulation, can predict the neurologic outcome in patients with out-of-hospital cardiac arrest (OHCA).

Methods

This was a retrospective observational study conducted in a single tertiary hospital intensive care unit. All adult OHCA survivors with admission lipid profiles were enrolled from March 2013 to December 2015. Good neurologic outcome was defined as discharge cerebral performance categories 1 and 2.

Results

Among 59 patients enrolled, 13 (22.0%) had a good neurologic outcome. Serum levels of HDL (56.7 vs. 40 mg/dL) and ApoA1 (117 vs. 91.6 mg/dL) were significantly higher in patients with a good outcome. Areas under the HDL and ApoA1 receiver operating curves to predict good outcomes were 0.799 and 0.759, respectively. The proportion of good outcome was significantly higher in patients in higher tertiles of HDL and ApoA1 (test for trend, both P=0.003). HDL (P=0.018) was an independent predictor in the multivariate logistic regression model.

Conclusion

Admission levels of HDL and ApoA1 are associated with neurologic outcome in patients with OHCA. Prognostic and potential therapeutic values of HDL and ApoA1 merit further evaluation in the post-cardiac arrest state, as in other systemic inflammatory conditions such as sepsis.

Lymphopaenia in cardiac arrest patients

Background

A decrease in circulating lymphocytes has been described as a marker of poor prognosis after septic shock; however, scarce data are available after cardiac arrest (CA). The aim of this study was to evaluate the impact of lymphopaenia after successful cardiopulmonary resuscitation.

Methods

This is a retrospective analysis of an institutional database including all adult CA patients admitted to the intensive care unit (ICU) between January 2007 and December 2014 who survived for at least 24 h. Demographic, CA-related data and ICU mortality were recorded as was lymphocyte count on admission and for the first 48 h. A cerebral performance category score of 3–5 at 3 months was considered as an unfavourable neurological outcome.

Results

Data from 377 patients were analysed (median age: 62 [IQRs: 52–75] years). Median time to return of spontaneous circulation (ROSC) was 15 [8–25] min and 232 (62%) had a non-shockable initial rhythm. ICU mortality was 58% (n = 217) and 246 (65%) patients had an unfavourable outcome at 3 months. The median lymphocyte count on admission was 1208 [700–2350]/mm³ and 151 (40%) patients had lymphopaenia (lymphocyte count <1000/mm³). Predictors of lymphopaenia on admission were older age, a shorter time to ROSC, prior use of corticosteroid therapy and high C-reactive protein levels on admission. ICU non-survivors had lower lymphocyte counts on admission than survivors (1100 [613–2317] vs. 1316 [891–2395]/mm³; p = 0.05) as did patients with unfavourable compared to those with favourable neurological outcomes (1100 [600–2013] vs. 1350 [919–2614]/mm³; p = 0.003). However, lymphopaenia on admission was not an independent predictor of poor outcomes in the entire population, but only among OHCA patients.

Conclusions

A low lymphocyte count is common in CA survivors and is associated with poor outcome after OHCA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-017-0308-z) contains supplementary material, which is available to authorized users.

Endotoxemia induces lung-brain coupling and multi-organ injury following cerebral ischemia-reperfusion

Post-ischemic neurodegeneration remains the principal cause of mortality following cardiac resuscitation. Recent studies have implicated gastrointestinal ischemia in the sepsis-like response associated with the post-cardiac arrest syndrome (PCAS). However, the extent to which the resulting low-grade endotoxemia present in up to 86% of resuscitated patients affects cerebral ischemia-reperfusion injury has not been investigated. Here we report that a single injection of low-dose lipopolysaccharide (50μg/kg, IP) delivered after global cerebral ischemia (GCI) induces blood-brain barrier permeability, microglial activation, cortical injury, and functional decline in vivo, compared to ischemia alone. And while GCI was sufficient to induce neutrophil (PMN) activation and recruitment to the post-ischemic CNS, minimal endotoxemia exhibited synergistic effects on markers of systemic inflammation including PMN priming, lung damage, and PMN burden within the lung and other non-ischemic organs including the kidney and liver. Our findings predict that acute interventions geared towards blocking the effects of serologically occult endotoxemia in survivors of cardiac arrest will limit delayed neurodegeneration, multi-organ dysfunction and potentially other features of PCAS. This work also introduces lung-brain coupling as a novel therapeutic target with broad effects on innate immune priming and post-ischemic neurodegeneration following cardiac arrest and related cerebrovascular conditions.

Recent developments in the management of patients resuscitated from cardiac arrest

Cardiac arrest is the leading cause of death in Europe and the United States. Many patients who are initially resuscitated die in the hospital, and hospital survivors often have substantial neurologic dysfunction. Most cardiac arrests are caused by coronary artery disease; patients with coronary artery disease likely benefit from early coronary angiography and intervention. After resuscitation, cardiac arrest patients remain critically ill and frequently suffer cardiogenic shock and multiorgan failure. Early cardiopulmonary stabilization is important to prevent worsening organ injury. To achieve best patient outcomes, comprehensive critical care management is needed, with primary goals of stabilizing hemodynamics and preventing progressive brain injury. Targeted temperature management is frequently recommended for comatose survivors of cardiac arrest to mitigate the neurologic injury that drives outcomes. Accurate neurologic assessment is central to managing care of cardiac arrest survivors and should combine physical examination with objective neurologic testing, with the caveat that delaying neurologic prognosis is essential to avoid premature withdrawal of supportive care. A combination of clinical findings and diagnostic results should be used to estimate the likelihood of functional recovery. This review focuses on recent advances in care and specific cardiac intensive care strategies that may improve morbidity and mortality for patients after cardiac arrest.

Early antibiotics administration during targeted temperature management after out-of-hospital cardiac arrest: a nationwide database study

Background

Patients resuscitated after cardiac arrest are reportedly at high risk for infection and sepsis, especially those treated with targeted temperature management (TTM). There is, however, limited evidence suggesting that early antibiotic use improves patient outcomes. We examined the hypothesis that early treatment with antibiotics reduces mortality in patients with cardiac arrest receiving TTM.

Methods

We identified 2803 patients with cardiogenic out-of-hospital cardiac arrest (OHCA) that were treated with TTM and were admitted to 371 hospitals that contribute to the Japanese Diagnosis Procedure Combination inpatient database between July 2007 and March 2013. Of these, 1272 received antibiotics within the first 2 days (antibiotics) and 1531 did not (control). We generated 802 propensity score-matched pairs.

Results

There was no significant difference in 30-day mortality between the groups (control vs. antibiotics; 33.0 % vs. 29.9 %; difference, 3.1 %; 95 % confidence interval [CI], −1.4 to 7.7 %, p = 0.18). Analysis using the hospital antibiotics prescribing rate as an instrumental variable showed that antibiotic use was not significantly associated with a reduction in 30-day mortality (6.6 %, CI 95 %, −0.5 to 13.7 %, p = 0.28). A subgroup analysis of patients who required extracorporeal membrane oxygenation (ECMO) indicated a significant difference in 30-day mortality between the 2 groups (62.9 % vs. 43.5 %; difference 19.3 %, CI 95 %, 5.9 to 32.7 %, p = 0.005). In the instrumental variable model, the estimated reduction in 30-day mortality associated with antibiotics was 18.2 % (CI 95 %, 21.3 to 34.4 %, p = 0.03) in ECMO patients.

Conclusions

Although there was no significant association between the use of antibiotics and mortality after overall cardiogenic OHCA treated with TTM, antibiotics may be beneficial in patients who require ECMO.