Transitions Between Circulatory States After Out-of-Hospital Cardiac Arrest: Protocol for an Observational, Prospective Cohort Study

The detrimental effects of intestinal injury mediated by inflammation are limited in cardiac arrest patients: A prospective cohort study

Background

Ischaemic intestines could be a driver of critical illness through an inflammatory response. We have previously published reports on a biomarker for intestinal injury, plasma Intestinal Fatty Acid Binding Protein (IFABP), and inflammatory biomarkers after out-of-hospital cardiac arrest (OHCA). In this post-hoc study we explored the potential indirect effects of intestinal injury mediated through the inflammatory response on organ dysfunction and mortality.

Methods

We measured IFABP and twenty-one inflammatory biomarkers in 50 patients at admission to intensive care unit after OHCA. First, we stratified patients on median IFABP and compared biomarkers between "low" and "high" IFABP. Second, by causal mediation analysis, we assessed effects of IFABP through the two most important inflammatory biomarkers, interleukin (IL)-6 and terminal complement complex (TCC), on day two circulatory variables, Sequential Organ Failure Assessment (SOFA)-score, and 30-day mortality.

Results

Cytokines and complement activation were higher in the high IFABP group. In mediation analysis, patients on the 75th percentile of IFABP, compared to the 25th percentile, had 53% (95% CI, 33-74; p < 0.001) higher risk of dying, where 13 (95% CI, 3-23; p = 0.01) percentage points were mediated through an indirect effect of IL-6. Similarly, the indirect effect of IFABP through IL-6 on SOFA-score was significant, but smaller than potential other effects. Effects through IL-6 on circulatory variables, and all effects through TCC, were not statistically significant and/or small.

Conclusion

Effects of intestinal injury mediated through inflammation on organ dysfunction and mortality were limited. Small, but significant, effects through IL-6 were noted.Trial registration: ClinicalTrials.gov: NCT02648061.

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.

Characteristics of circulatory failure after out-of-hospital cardiac arrest: a prospective cohort study

Background

Circulatory failure after out-of-hospital cardiac arrest (OHCA) as part of the postcardiac arrest syndrome (PCAS) is believed to be caused by an initial myocardial depression that later subsides into a superimposed vasodilatation. However, the relative contribution of myocardial dysfunction and systemic inflammation has not been established. Our objective was to describe the macrocirculatory and microcirculatory failure in PCAS in more detail.

Methods

We included 42 comatose patients after OHCA where circulatory variables were invasively monitored from admission until day 5. We measured the development in cardiac power output (CPO), stroke work (SW), aortic elastance, microcirculatory metabolism, inflammatory and cardiac biomarkers and need for vasoactive medications. We used survival analysis and Cox regression to assess time to norepinephrine discontinuation and negative fluid balance, stratified by inflammatory and cardiac biomarkers.

Results

CPO, SW and oxygen delivery increased during the first 48 hours. Although the estimated afterload fell, the blood pressure was kept above 65 mmHg with a diminishing need for norepinephrine, indicating a gradually re-established macrocirculatory homoeostasis. Time to norepinephrine discontinuation was longer for patients with higher pro-brain natriuretic peptide concentration (HR 0.45, 95% CI 0.21 to 0.96), while inflammatory biomarkers and other cardiac biomarkers did not predict the duration of vasoactive pressure support. Markers of microcirculatory distress, such as lactate and venous-to-arterial carbon dioxide difference, were normalised within 24 hours.

Conclusion

The circulatory failure was initially characterised by reduced CPO and SW, however, microcirculatory and macrocirculatory homoeostasis was restored within 48 hours. We found that biomarkers indicating acute heart failure, and not inflammation, predicted longer circulatory support with norepinephrine. Taken together, this indicates an early and resolving, rather than a late and emerging vasodilatation.

Trial registration

NCT02648061.

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

BACKGROUND

Whole body ischemia and reperfusion injury after cardiac arrest leads to the massive inflammation clinically manifested in the post-cardiac arrest syndrome. Previous studies on the inflammatory effect on circulatory failure after cardiac arrest have either investigated a selected patient group or a limited part of the inflammatory mechanisms. We examined the association between cardiac arrest characteristics and inflammatory biomarkers, and between inflammatory biomarkers and circulatory failure after cardiac arrest, in an unselected patient cohort.

METHODS

This was a prospective study of 50 consecutive patients with out-of-hospital cardiac arrest. Circulation was invasively monitored from admission until day five, whereas inflammatory biomarkers, i.e. complement activation, cytokines and endothelial injury, were measured daily. We identified predictors for an increased inflammatory response, and associations between the inflammatory response and circulatory failure.

RESULTS

We found a marked and broad inflammatory response in patients after cardiac arrest, which was associated with clinical outcome. Long time to return of spontaneous circulation and high lactate level at admission were associated with increased complement activation (TCC and C3bc), pro-inflammatory cytokines (IL-6, IL-8) and endothelial injury (syndecan-1) at admission. These biomarkers were in turn significantly associated with lower mean arterial blood pressure, lower cardiac output and lower systemic vascular resistance, and increased need of circulatory support in the initial phase. High levels of TCC and IL-6 at admission were significantly associated with increased 30-days mortality.

CONCLUSION

Inflammatory biomarkers, including complement activation, cytokines and endothelial injury, were associated with increased circulatory failure in the initial period after cardiac arrest.

Circulatory trajectories after out-of-hospital cardiac arrest: a prospective cohort study

BACKGROUND

Circulatory failure frequently occurs after out-of-hospital cardiac arrest (OHCA) and is part of post-cardiac arrest syndrome (PCAS). The aim of this study was to investigate circulatory disturbances in PCAS by assessing the circulatory trajectory during treatment in the intensive care unit (ICU).

METHODS

This was a prospective single-center observational cohort study of patients after OHCA. Circulation was continuously and invasively monitored from the time of admission through the following five days. Every hour, patients were classified into one of three predefined circulatory states, yielding a longitudinal sequence of states for each patient. We used sequence analysis to describe the overall circulatory development and to identify clusters of patients with similar circulatory trajectories. We used ordered logistic regression to identify predictors for cluster membership.

RESULTS

Among 71 patients admitted to the ICU after OHCA during the study period, 50 were included in the study. The overall circulatory development after OHCA was two-phased. Low cardiac output (CO) and high systemic vascular resistance (SVR) characterized the initial phase, whereas high CO and low SVR characterized the later phase. Most patients were stabilized with respect to circulatory state within 72 h after cardiac arrest. We identified four clusters of circulatory trajectories. Initial shockable cardiac rhythm was associated with a favorable circulatory trajectory, whereas low base excess at admission was associated with an unfavorable circulatory trajectory.

CONCLUSION

Circulatory failure after OHCA exhibits time-dependent characteristics. We identified four distinct circulatory trajectories and their characteristics. These findings may guide clinical support for circulatory failure after OHCA.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02648061.

Resistin-Can it be a new early marker for prognosis in patients who survive after a cardiac arrest? A pilot study

AIM

The aim of our study was to evaluate the potential role of resistin in estimating the 30 days prognosis in patients with hypoxic-ischemic organ injury who survived after a cardiac arrest (CA).

MATERIALS AND METHODS

The study included 40 patients resuscitated after a non-traumatic out-of-hospital CA admitted in Emergency Department (ED). All patients were followed for 30 days after CA or until death. Clinical data on admission were recorded. Blood samples were collected on admission in ED (0-time interval), and at 6, 12, 24, 48- and 72-hours following resuscitation. Serum concentrations of resistin, S100B and neuron specific enolase (NSE) were measured. Several predictive scores for the mortality at 30 days were created with logistic regressions.

RESULTS

At each time interval, median serum levels of resistin and S100 B were significantly higher in non-survivors compared to survivors. For NSE, plasma levels were significantly lower in survivors as compared to non-survivors at 48 and 72 hours, respectively. Accurate predictive scores for 30-days mortality were the ones which included the values of resistin and S100B measured at 12 hours after admittance [AUC 0.938 (0.813-0.989), sensitivity 85.71% (67.3%- 96%), specificity 91.67% (61.5%'99.8%), p<0.001], which included the values of all three markers measured at 12 hours after admittance [AUC 0.955 (0.839-0.995), sensitivity 82.14% (63.1%'93.9%), specificity 100.00% (73.5%'100.0%), p<0.001] and the that included the values of resistin and S-100B at 6 hours together with serum lactate on admission [AUC = 0.994 (0.901-1.0), sensitivity 96.4% (81.7%'99.9%), specificity 100.00% (73.5%'100.0%), p<0.001].

CONCLUSION

In our study, serum levels of resistin or a combination of resistin with S-100B or resistin with S-100B and lactate, were highly predictive for 30 days mortality in resuscitated patients after CA. Further studies on large number of patients are needed to confirm our data.