The inflammatory response is related to circulatory failure after out-of-hospital cardiac arrest: A prospective cohort study

Cardiac arrest related lung edema: examining the role of downtimes in transpulmonary thermodilution analysis

Pulmonary edema and its association with low flow times has been observed in postcardiac arrest patients. However, diagnosis of distinct types of lung pathology is difficult.The aim of this study was to investigate pulmonary edema by transpulmonary thermodilution (TPTD) after out-of-hospital cardiac arrest (OHCA), and the correlation to downtimes. In this retrospective single-center study consecutive patients with return of spontaneous circulation (ROSC) following OHCA, age ≥ 18, and applied TPTD were enrolled. According to downtimes, patients were divided into a short and a long no-flow-time group, and data of TPTD were analysed. We identified 45 patients (n = 25 short no-flow time; n = 20 long no-flow time) who met the inclusion criteria. 24 h after ROSC, the extra vascular lung water index (EVLWI) was found to be lower in the group with short no-flow time compared to the group with long no-flow time (10.7 ± 3.5 ml/kg vs. 12.8 ± 3.9 ml/kg; p = 0.08) and remained at a similar level 48 h (10.9 ± 4.3 ml/kg vs. 12.9 ± 4.9 ml/kg; p = 0.25) and 72 h (11.1 ± 5.0 ml/kg vs. 13.9 ± 7.7 ml/kg; p = 0.27) post-ROSC. We found a statistically significant and moderate correlation between no-flow duration and EVLWI 48 h (r = 0.51; p = 0.002) and 72 h (r = 0.54; p = 0.004) post-ROSC. Pulmonary vascular permeability index (PVPI) was not correlated with downtimes. Our observation underlines the presence of cardiac arrest-related lung edema by determination of EVLWI. The duration of no-flow times is a relevant factor for increased extravascular lung water index.

The Effect of Cytokine Adsorption on Leukocyte and Platelet Activation after Extracorporeal Cardiopulmonary Resuscitation

BACKGROUND

 Post-cardiac arrest syndrome (PCAS) is a frequent complication following successful cardiopulmonary resuscitation and correlates with poor outcome. PCAS is characterized by an excessive inflammatory response to whole-body ischemia and reperfusion. Cytokine adsorption was suggested as an adjunctive treatment option for the removal of cytokines from the patients' blood to restore the physiological equilibrium of pro- and anti-inflammatory activity and thus mitigate hemodynamic instability and end-organ complications.

MATERIAL AND METHODS

 To better understand the cellular effects of cytokine adsorption in patients receiving extracorporeal cardiopulmonary resuscitation (ECPR) after in- and out-of-hospital cardiac arrest, we compared the activation status of neutrophils, monocytes, and platelets as well as the formation of platelet-leukocyte complexes in intravenous whole blood samples from an exploratory subgroup (n = 24) from the randomized CYTER study.

RESULT

 At 48 hours after initiation of ECPR, flow cytometry analyses did neither reveal significant differences in neutrophil (CD11b, CD66b, L-selectin, and PSGL-1) and monocyte (CD11b, L-selectin, and PSGL-1) surface molecule expression nor in circulating platelet-monocyte complexes between patients receiving cytokine adsorption and those without.

CONCLUSION

 Data did not show a relevant effect of cytokine adsorption on neutrophil and monocyte activation during the first 48 hours after initiation of ECPR.

Postresuscitation management

PURPOSE OF REVIEW

To describe the most recent scientific evidence on ventilation/oxygenation, circulation, temperature control, general intensive care, and prognostication after successful resuscitation from adult cardiac arrest.

RECENT FINDINGS

Targeting a lower oxygen target (90-94%) is associated with adverse outcome. Targeting mild hypercapnia is not associated with improved functional outcomes or survival. There is no compelling evidence supporting improved outcomes associated with a higher mean arterial pressure target compared to a target of >65 mmHg. Noradrenalin seems to be the preferred vasopressor. A low cardiac index is common over the first 24 h but aggressive fluid loading and the use of inotropes are not associated with improved outcome. Several meta-analyses of randomized clinical trials show conflicting results whether hypothermia in the 32-34°C range as compared to normothermia or no temperature control improves functional outcome. The role of sedation is currently under evaluation. Observational studies suggest that the use of neuromuscular blockade may be associated with improved survival and functional outcome. Prophylactic antibiotic does not impact on outcome. No single predictor is entirely accurate to determine neurological prognosis. The presence of at least two predictors of severe neurological injury indicates that an unfavorable neurological outcome is very likely.

SUMMARY

Postresuscitation care aims for normoxemia, normocapnia, and normotension. The optimal target core temperature remains a matter of debate, whether to implement temperature management within the 32-34°C range or focus on fever prevention, as recommended in the latest European Resuscitation Council/European Society of Intensive Care Medicine guidelines Prognostication of neurological outcome demands a multimodal approach.

Resuscitation-associated endotheliopathy (RAsE): a conceptual framework based on a systematic review and meta-analysis

INTRODUCTION

Shock-induced endotheliopathy (SHINE), defined as a profound sympathoadrenal hyperactivation in shock states leading to endothelial activation, glycocalyx damage, and eventual compromise of end-organ perfusion, was first described in 2017. The aggressive resuscitation therapies utilised in treating shock states could potentially lead to further worsening endothelial activation and end-organ dysfunction.

OBJECTIVE

This study aimed to systematically review the literature on resuscitation-associated and resuscitation-induced endotheliopathy.

METHODS

A predetermined structured search of literature published over an 11-year and 6-month period (1 January 2011 to 31 July 2023) was performed in two indexed databases (PubMed/MEDLINE and Embase) per PRISMA guidelines. Inclusion was restricted to original studies published in English (or with English translation) reporting on endothelial dysfunction in critically ill human subjects undergoing resuscitation interventions. Reviews or studies conducted in animals were excluded. Qualitative synthesis of studies meeting the inclusion criteria was performed. Studies reporting comparable biomarkers of endothelial dysfunction post-resuscitation were included in the quantitative meta-analysis.

RESULTS

Thirty-two studies met the inclusion criteria and were included in the final qualitative synthesis. Most of these studies (47%) reported on a combination of mediators released from endothelial cells and biomarkers of glycocalyx breakdown, while only 22% reported on microvascular flow changes. Only ten individual studies were included in the quantitative meta-analysis based on the comparability of the parameters assessed. Eight studies measured syndecan-1, with a heterogeneity index, I2 = 75.85% (pooled effect size, mean = 0.27; 95% CI - 0.07 to 0.60; p = 0.12). Thrombomodulin was measured in four comparable studies (I2 = 78.93%; mean = 0.41; 95% CI - 0.10 to 0.92; p = 0.12). Three studies measured E-selectin (I2 = 50.29%; mean =  - 0.15; 95% CI - 0.64 to 0.33; p = 0.53), and only two were comparable for the microvascular flow index, MFI (I2 = 0%; mean =  - 0.80; 95% CI - 1.35 to - 0.26; p < 0.01).

CONCLUSION

Resuscitation-associated endotheliopathy (RAsE) refers to worsening endothelial dysfunction resulting from acute resuscitative therapies administered in shock states. In the included studies, syndecan-1 had the highest frequency of assessment in the post-resuscitation period, and changes in concentrations showed a statistically significant effect of the resuscitation. There are inadequate data available in this area, and further research and standardisation of the ideal assessment and panel of biomarkers are urgently needed.

Inflammatory response after out-of-hospital cardiac arrest-Impact on outcome and organ failure development

BACKGROUND

Post-cardiac arrest syndrome that occurs in out-of-hospital cardiac arrest (OHCA) patients is characterized by inflammatory response. We conducted a scoping review of current evidence regarding several inflammatory markers' usefulness for assessment of patient outcome and illness severity. We also discuss the proposed underlying mechanisms leading to inflammatory response after OHCA.

METHODS

We searched the MEDLINE, PubMed Central, Cochrane CENTRAL and Web of Science Core Collection databases with the following search terms: ("inflammation" OR "cytokines") AND "out-of-hospital cardiac arrest." Each inflammatory marker found was combined with "out-of-hospital cardiac arrest" using "AND" to find further relevant studies. We included original studies measuring inflammatory markers in adult OHCA patients that assessed their prognostic capabilities for mortality, neurological outcome, or organ failure severity.

RESULTS

Fifty-nine studies met the inclusion criteria, covering in total 65 different markers. Interleukin-6 (IL-6), procalcitonin (PCT) and C-reactive protein (CRP) were the most studied markers, and they were associated with poor outcomes in 13/15, 13/14 and 11/17 studies, respectively. Based on area under the receiver operating characteristic curve (AUC) value, the time point of best discriminatory capacity for poor outcome was ICU admission for IL-6 (median AUC 0.78, range 0.71-0.98) and day one after OHCA for PCT (median AUC 0.84, range 0.61-0.98). Seven studies reported AUCs for CRP (range 0.52-0.76) with no measurement time point being superior to others. The association of IL-6 and PCT with outcome appeared stronger in studies with more severely ill patients. Studies reported conflicting results regarding each marker's association with organ failure severity.

CONCLUSION

Inflammatory markers are potentially useful for early risk stratification after OHCA. PCT and IL-6 have moderate prognostic value during the first 24 h of the ICU stay. Predictive accuracy appears to be associated with the study overall event rate.

Acute Respiratory Distress Syndrome in Patients with Cardiovascular Disease

Heart and lung interaction within the thoracic cavity is well known during inhalation and exhalation, both spontaneously and during mechanical ventilation. Disease and dysfunction of one organ affect the function of the other. A review of the cause-and-effect relationship between cardiovascular disease and acute respiratory distress syndrome (ARDS) is of significance, as the disease burden of both conditions has both a national and global impact on health care. This literature review examines the relationship between cardiovascular disease and ARDS over the past 25 years.

Blood pressure targets and management during post-cardiac arrest care

Blood pressure is one modifiable physiological target in patients treated in the intensive care unit after cardiac arrest. Current Guidelines recommend targeting a mean arterial pressure (MAP) of higher than 65-70 mmHg using fluid resuscitation and the use of vasopressors. Management strategies will vary based in the setting, i.e. the pre-hospital compared to the in-hospital phase. Epidemiological data suggest that some degree of hypotension requiring vasopressors occur in almost 50% of patients. A higher MAP could theoretically increase coronary blood flow but on the other hand the use of vasopressor may result in an increase in cardiac oxygen demand and arrhythmia. An adequate MAP is paramount for maintaining cerebral blood flow. In some cardiac arrest patients the cerebral autoregulation may be disturbed resulting in the need for higher MAP in order to avoid decreasing cerebral blood flow. Thus far, four studies including little more than 1000 patients have compared a lower and higher MAP target in cardiac arrest patients. The achieved mean difference of MAP between groups has varied from 10-15 mmHg. Based on these studies a Bayesian meta-analysis suggests that the posterior probability that a future study would find treatment effects higher than a 5% difference between groups to be less than 50%. On the other hand, this analysis also suggests, that the likelihood of harm with a higher MAP target is also low. Noteworthy is that all studies to date have focused mainly on patients with a cardiac cause of the arrest with the majority of patients being resuscitated from a shockable initial rhythm. Future studies should aim to include also non-cardiac causes and aim to target a wider separation in MAP between groups.

Inflammation and Syndecan-4 Shedding from Cardiac Cells in Ischemic and Non-Ischemic Heart Disease

Circulating biomarkers reflecting cardiac inflammation are needed to improve the diagnostics and guide the treatment of heart failure patients. The cardiac production and shedding of the transmembrane proteoglycan syndecan-4 is upregulated by innate immunity signaling pathways. Here, we investigated the potential of syndecan-4 as a blood biomarker of cardiac inflammation. Serum syndecan-4 was measured in patients with (i) non-ischemic, non-valvular dilated cardiomyopathy (DCM), with (n = 71) or without (n = 318) chronic inflammation; (ii) acute myocarditis (n = 15), acute pericarditis (n = 3) or acute perimyocarditis (23) and (iii) acute myocardial infarction (MI) at day 0, 3 and 30 (n = 119). Syndecan-4 was investigated in cultured cardiac myocytes and fibroblasts (n = 6–12) treated with the pro-inflammatory cytokines interleukin (IL)-1β and its inhibitor IL-1 receptor antagonist (IL-1Ra), or tumor necrosis factor (TNF)α and its specific inhibitor infliximab, an antibody used in treatment of autoimmune diseases. The levels of serum syndecan-4 were comparable in all subgroups of patients with chronic or acute cardiomyopathy, independent of inflammation. Post-MI, syndecan-4 levels were increased at day 3 and 30 vs. day 0. IL-1Ra attenuated IL-1β-induced syndecan-4 production and shedding in vitro, while infliximab had no effect. In conclusion, syndecan-4 shedding from cardiac myocytes and fibroblasts was attenuated by immunomodulatory therapy. Although its circulating levels were increased post-MI, syndecan-4 did not reflect cardiac inflammatory status in patients with heart disease.

Modulation of inflammation by treatment with tocilizumab after out-of-hospital cardiac arrest and associations with clinical status, myocardial- and brain injury

AIM

To investigate how the inflammatory response after out-of-hospital cardiac arrest (OHCA) is modulated by blocking IL-6-mediated signalling with tocilizumab, and to relate induced changes to clinical status, myocardial- and brain injury.

METHODS

This is a preplanned substudy of the IMICA trial (ClinicalTrials.gov, NCT03863015). Upon admission 80 comatose OHCA patients were randomized to infusion of tocilizumab or placebo. Inflammation was characterized by a cytokine assay, CRP, and leukocyte differential count; myocardial injury by TnT and NT-proBNP; brain injury by neuron-specific enolase (NSE) and Neurofilament Light chain (NFL), while sequential organ assessment (SOFA) score and Vasoactive-Inotropic Score (VIS) represented overall clinical status.

RESULTS

Responses for IL-5, IL-6, IL-17, neutrophil as well as monocyte counts, and VIS were affected by tocilizumab treatment (all p < 0.05), while there was no effect on levels of NFL. IL-5 and IL-6 were substantially increased by tocilizumab, while IL-17 was lowered. Neutrophils and monocytes were lower at 24 and 48 hours, and VIS was lower at 24 hours, for the tocilizumab group compared to placebo. Multiple correlations were identified for markers of organ injury and clinical status versus inflammatory markers; this included correlations of neutrophils and monocytes with TnT, NSE, NFL, SOFA- and VIS score for the tocilizumab but not the placebo group. NT-proBNP, NFL and SOFA score correlated with CRP in both groups.

CONCLUSIONS

Treatment with tocilizumab after OHCA modulated the inflammatory response with notable increases for IL-5, IL-6, and decreases for neutrophils and monocytes, as well as reduced vasopressor and inotropy requirements.

Pediatric Extracorporeal Cardiopulmonary Resuscitation: Development of a Porcine Model and the Influence of Cardiopulmonary Resuscitation Duration on Brain Injury

Background The primary objective was to develop a porcine model of prolonged (30 or 60 minutes) pediatric cardiopulmonary resuscitation (CPR) followed by 22- to 24-hour survival with extracorporeal life support, and secondarily to evaluate differences in neurologic injury. Methods and Results Ten-kilogram, 4-week-old female piglets were used. First, model development established the technique (n=8). Then, a pilot study was conducted (n=15). After 80% survival was achieved in the final 5 pilot animals, a proof-of-concept randomized study was completed (n=11). Shams (n=6) underwent anesthesia only. Severe neurological injury was determined by a composite score of mitochondrial function, neuropathology, and cerebral metabolism: scale of 0-6 (severe: >3). Among 15 piglets in the pilot study, overall survival was 10 (67%); of the final 5, overall survival was 4 (80%). Eleven piglets were then randomized to 60 (CPR60, n=5) or 30 minutes of CPR (CPR30, n=5); 1 animal was excluded from prerandomization for intra-abdominal hemorrhage (10/11, 91% survival). Three of 5 animals in the CPR60 group had severe neurological injury scores versus 1 of 5 in the CPR30 group (P=0.52). During ECMO, CPR60 animals had lower pH (CPR60: 7.4 [IQR 7.4-7.4] versus CPR30: 7.5 [IQR 7.4-7.5], P=0.022), higher lactate (CPR60: 6.8 [IQR 6.8-11] versus CPR30: 4.2 [IQR 4.1-4.3] mmol/L; P=0.012), and higher ICP (CPR60: 19.3 [IQR 11.7-29.3] versus CPR30: 7.9 [IQR 6.7-9.3] mm Hg; P=0.037). Both groups had greater mitochondrial injury than shams (CPR60: P<0.001; CPR30: P<0.001). CPR60 did not differ from CPR30 in mitochondrial respiration, neuropathology, or cerebral metabolism. Conclusions A pediatric porcine model of extracorporeal cardiopulmonary resuscitation after 60 and 30 minutes of CPR consistently resulted in 24-hour survival with more severe lactic acidosis in the 60-minute cohort.

Do Body Mass Index and Nutritional Risk Score 2002 Influence the In-Hospital Mortality of Patients Following Cardiac Arrest?

BACKGROUND

Contemporarily, cardiac arrest (CA) remains one of the leading causes of death. Poor nutritional status can increase the post-CA mortality risk. The aim of this study was to determine the relationship between body mass index (BMI) and Nutritional Risk Score 2002 (NRS 2002) results and in-hospital mortality in patients admitted to the intensive care unit (ICU) after in-hospital and out-of-hospital cardiac arrest.

METHODS

A retrospective study and analysis of medical records of 161 patients admitted to the ICU of the University Clinical Hospital in Wrocław (Wrocław, Poland) was conducted.

RESULTS

No significant differences in body mass index (BMI) and nutritional risk score (NRS 2002) values were observed between non-survivors and survivors. Non-survivors had significantly lower albumin concentration (p = 0.017) and total cholesterol (TC) (p = 0.015). In multivariate analysis BMI and NRS 2002 scores were not, per se, associated with the in-hospital mortality defined as the odds of death (Model 1: p: 0.700, 0.430; Model 2: p: 0.576, 0.599). Univariate analysis revealed significant associations between the hazard ratio (HR) and TG (p ≈ 0.017, HR: 0.23) and hsCRP (p ≈ 0.018, HR: 0.34). In multivariate analysis, mortality risk over time was influenced by higher scores in parameters such as BMI (HR = 0.164; p = 0.048) and hsCRP (HR = 1.006, p = 0.002).

CONCLUSIONS

BMI and NRS 2002, on their own (unconditionally - in the whole study group) did not alter the odds of mortality in patients admitted to the intensive care unit (ICU) after in-hospital and out-of-hospital cardiac arrest. The risk of in-hospital mortality (expressed as hazard ratio - the risk over the time period of the study) increased with an increase in BMI but not with NRS 2002.

Non-Invasive Pulsatile Shear Stress Modifies Endothelial Activation; A Narrative Review

The monolayer of cells that line both the heart and the entire vasculature is the endothelial cell (EC). These cells respond to external and internal signals, producing a wide array of primary or secondary messengers involved in coagulation, vascular tone, inflammation, and cell-to-cell signaling. Endothelial cell activation is the process by which EC changes from a quiescent cell phenotype, which maintains cellular integrity, antithrombotic, and anti-inflammatory properties, to a phenotype that is prothrombotic, pro-inflammatory, and permeable, in addition to repair and leukocyte trafficking at the site of injury or infection. Pathological activation of EC leads to increased vascular permeability, thrombosis, and an uncontrolled inflammatory response that leads to endothelial dysfunction. This pathological activation can be observed during ischemia reperfusion injury (IRI) and sepsis. Shear stress (SS) and pulsatile shear stress (PSS) are produced by mechanical frictional forces of blood flow and contraction of the heart, respectively, and are well-known mechanical signals that affect EC function, morphology, and gene expression. PSS promotes EC homeostasis and cardiovascular health. The archetype of inducing PSS is exercise (i.e., jogging, which introduces pulsations to the body as a function of the foot striking the pavement), or mechanical devices which induce external pulsations to the body (Enhanced External Pulsation (EECP), Whole-body vibration (WBV), and Whole-body periodic acceleration (WBPA aka pGz)). The purpose of this narrative review is to focus on the aforementioned noninvasive methods to increase PSS, review how each of these modify specific diseases that have been shown to induce endothelial activation and microcirculatory dysfunction (Ischemia reperfusion injury-myocardial infarction and cardiac arrest and resuscitation), sepsis, and lipopolysaccharide-induced sepsis syndrome (LPS)), and review current evidence and insight into how each may modify endothelial activation and how these may be beneficial in the acute and chronic setting of endothelial activation and microvascular dysfunction.

Resuscitation highlights in 2021

BACKGROUND

This review is the latest in a series of regular annual reviews undertaken by the editors and aims to highlight some of the key papers published in Resuscitation during 2021.

METHODS

Hand-searching by the editors of all papers published in Resuscitation during 2021. Papers were selected based on then general interest and novelty and were categorised into themes.

RESULTS

98 papers were selected for brief mention.

CONCLUSIONS

Resuscitation science continues to evolve and incorporates all links in the chain of survival.

Targeted temperature management after cardiac arrest is associated with reduced metabolism of pantoprazole - A probe drug of CYP2C19 metabolism

OBJECTIVE

Targeted temperature management (TTM) is part of standard post-resuscitation care. TTM may downregulate cytochrome enzyme activity and thus impact drug metabolism. This study compared the pharmacokinetics (PK) of pantoprazole, a probe drug of CYP2C19-dependent metabolism, at different stages of TTM following cardiac arrest.

METHODS

This prospective controlled study was performed at the Medical University of Vienna and enrolled 16 patients following cardiac arrest. The patients completed up to three study periods (each lasting 24 h) in which plasma concentrations of pantoprazole were quantified: (P1) hypothermia (33 °C) after admission, (P2) normothermia after rewarming (36 °C, intensive care), and (P3) normothermia during recovery (normal ward, control group). PK was analysed using non-compartmental analysis and nonlinear mixed-effects modelling.

RESULTS

16 patients completed periods P1 and P2; ten completed P3. The median half-life of pantoprazole was 2.4 h (quartiles: 1.8-4.8 h) in P1, 2.8 h (2.1-6.8 h, p = 0.046 vs. P1, p = 0.005 vs. P3) in P2 and 1.2 h (0.9 - 2.3 h, p = 0.007 vs. P1) in P3. A two-compartment model described the PK data best. Typical values for clearance were estimated separately for each study period, indicating 40% and 29% reductions during P1 and P2, respectively, compared to P3. The central volume of distribution was estimated separately for P2, indicating a 64% increase compared to P1 and P3.

CONCLUSION

CYP2C19-dependent drug metabolism is downregulated during TTM following cardiac arrest. These results may influence drug choice and dosing of similarly metabolized drugs and may be helpful for designing studies in similar clinical situations.