Can we predict patient outcome before extracorporeal membrane oxygenation for refractory cardiac arrest?

Comparing clinical only and combined clinical laboratory models for ECPR outcomes in refractory cardiac arrest

Extracorporeal cardiopulmonary resuscitation (ECPR) improves survival for prolonged cardiac arrest (CA) but carries significant risks and costs due to ECMO. Previous predictive models have been complex, incorporating both clinical data and parameters obtained after CPR or ECMO initiation. This study aims to compare a simpler clinical-only model with a model that includes both clinical and pre-ECMO laboratory parameters, to refine patient selection and improve ECPR outcomes. Medical records between January 2012 and January 2019 in our institution were retrospectively reviewed. Patients who met the following criteria were enrolled in the ECPR program: age 18-75 years, CCPR started with CA in < 5 min, CA was assumed to be of heart origin, and refractory CA. Survivors had similar underlying diseases and younger age without statistical significance (57.0 vs. 61.0 years, p = 0.117). Survivors had significantly higher rates of initial shockable rhythm, pulseless ventricular tachycardia and ventricular fibrillation, shorter low-flow time (CPR-to-ECMO time), lower lactate levels, and higher initial pH. Survival to discharge was higher for emergency department CA than for out-of-hospital and in-hospital CA (63.3% vs. 35.3%, p = 0.007). Two models were used for evaluating survival to discharge and good neurological outcomes. Model 1, short version based on clinical factors, (S1, survival score 1; F1, function score 1) included the patient's characteristics before ECPR, whereas Model 2, full version included clinical factors and laboratory data including lactate and pH levels (S2, survival score 2; F2, function score 2). Both Model 1(S1) and Model 2(S2) showed good predictive ability for survival to discharge with areas under the receiver operating characteristic (AUROCs) of 0.79 and 0.83, respectively. Model 1(F1) and Model 2(F2) revealed prediction power for good neurological outcomes, with AUROCs of 0.80 and 0.79, respectively. The AUROCs of survival score Model 1(S1) and 2(S2) and function score Model 1(F1) and 2(F2) were not significantly different. This study demonstrates that clinical factors alone can effectively predict survival to discharge and favorable neurological outcomes at 6 months. This emphasizes the importance of early prognostic evaluation and supports the use of clinical data as a practical tool for clinicians in decision-making for this difficult situation.

The Pre-ECPR Score: Developing and Validating a Multivariable Prediction Model for Favorable Neurological Outcomes in Patients Undergoing Extracorporeal Cardiopulmonary Resuscitation

OBJECTIVES

Extracorporeal cardiopulmonary resuscitation (ECPR) can save patients with refractory cardiac arrest; however, according to recent meta-analyses, only 20% of patients achieve favorable outcomes (Modified Rankin Scale 0-3). We aimed to develop and validate an ECPR prediction model to improve patient selection.

DESIGN

Prognostic model development and internal validation study.

SETTING

Single-center study.

PARTICIPANTS

All 120 normothermic ECPR patients treated at Sahlgrenska University Hospital between January 2010 and October 2021.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Multivariable logistic regression was used to develop the PRognostic Evaluation of ECPR (Pre-ECPR) score. Model performance was assessed through the area under curve (AUC) and compared with the Extracorporeal Life Support Organization (ELSO) "Example of selection criteria for ECPR" for 1-year survival with favorable outcomes. The positive predictive value (PPV) was calculated. Favorable outcomes occurred in 27.5% of the patients. The Pre-ECPR score, incorporating age, no-flow/initial rhythm (a composite variable), total cardiac arrest time, signs of life, pupil dilation, regional cerebral oxygen saturation, arterial pH, and end-tidal CO2, demonstrated an AUC of 0.87 (95% confidence interval [CI] 0.77-0.93). In internal cross-validation, the AUC of 0.79 (95% CI 0.67-0.88) significantly outperformed the ELSO criteria AUC of 0.63 (95% CI 0.54-0.72, p = 0.012). Pre-ECPR score probabilities >6.4% showed 100% sensitivity and a PPV of 40.5% for favorable outcomes.

CONCLUSIONS

The Pre-ECPR score combines multiple weighted predictors to provide a single balanced probability of favorable outcomes in ECPR patient selection. In cross-validation, it demonstrated significantly more favorable discriminatory performance than that of the ELSO criteria.

[Construction and validation of an in-hospital mortality risk prediction model for patients receiving VA-ECMO: a retrospective multi-center case-control study]

OBJECTIVE

To investigate the risk factors of in-hospital mortality and establish a risk prediction model for patients receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO).

METHODS

We retrospectively collected the data of 302 patients receiving VA-ECMO in ICU of 3 hospitals in Guangdong Province between January, 2015 and January, 2022 using a convenience sampling method. The patients were divided into a derivation cohort (201 cases) and a validation cohort (101 cases). Univariate and multivariate logistic regression analyses were used to analyze the risk factors for in-hospital death of these patients, based on which a risk prediction model was established in the form of a nomogram. The receiver operator characteristic (ROC) curve, calibration curve and clinical decision curve were used to evaluate the discrimination ability, calibration and clinical validity of this model.

RESULTS

The in-hospital mortality risk prediction model was established based the risk factors including hypertension (OR=3.694, 95% CI: 1.582-8.621), continuous renal replacement therapy (OR=9.661, 95%CI: 4.103-22.745), elevated Na2 + level (OR=1.048, 95% CI: 1.003-1.095) and increased hemoglobin level (OR=0.987, 95% CI: 0.977-0.998). In the derivation cohort, the area under the ROC curve (AUC) of this model was 0.829 (95% CI: 0.770-0.889), greater than those of the 4 single factors (all AUC < 0.800), APACHE II Score (AUC=0.777, 95% CI: 0.714-0.840) and the SOFA Score (AUC=0.721, 95% CI: 0.647-0.796). The results of internal validation showed that the AUC of the model was 0.774 (95% CI: 0.679-0.869), and the goodness of fit test showed a good fitting of this model (χ2=4.629, P>0.05).

CONCLUSION

The risk prediction model for in-hospital mortality of patients on VA-ECMO has good differentiation, calibration and clinical effectiveness and outperforms the commonly used disease severity scoring system, and thus can be used for assessing disease severity and prognostic risk level in critically ill patients.

Predictive models in extracorporeal membrane oxygenation (ECMO): a systematic review

PURPOSE

Extracorporeal membrane oxygenation (ECMO) has been increasingly used in the last years to provide hemodynamic and respiratory support in critically ill patients. In this scenario, prognostic scores remain essential to choose which patients should initiate ECMO. This systematic review aims to assess the current landscape and inform subsequent efforts in the development of risk prediction tools for ECMO.

METHODS

PubMed, CINAHL, Embase, MEDLINE and Scopus were consulted. Articles between Jan 2011 and Feb 2022, including adults undergoing ECMO reporting a newly developed and validated predictive model for mortality, were included. Studies based on animal models, systematic reviews, case reports and conference abstracts were excluded. Data extraction aimed to capture study characteristics, risk model characteristics and model performance. The risk of bias was evaluated through the prediction model risk-of-bias assessment tool (PROBAST). The protocol has been registered in Open Science Framework ( https://osf.io/fevw5 ).

RESULTS

Twenty-six prognostic scores for in-hospital mortality were identified, with a study size ranging from 60 to 4557 patients. The most common candidate variables were age, lactate concentration, creatinine concentration, bilirubin concentration and days in mechanical ventilation prior to ECMO. Five out of 16 venous-arterial (VA)-ECMO scores and 3 out of 9 veno-venous (VV)-ECMO scores had been validated externally. Additionally, one score was developed for both VA and VV populations. No score was judged at low risk of bias.

CONCLUSION

Most models have not been validated externally and apply after ECMO initiation; thus, some uncertainty whether ECMO should be initiated still remains. It has yet to be determined whether and to what extent a new methodological perspective may enhance the performance of predictive models for ECMO, with the ultimate goal to implement a model that positively influences patient outcomes.

Prognostic models for mortality risk in patients requiring ECMO

PURPOSE

To provide an overview and evaluate the performance of mortality prediction models for patients requiring extracorporeal membrane oxygenation (ECMO) support for refractory cardiocirculatory or respiratory failure.

METHODS

A systematic literature search was undertaken to identify studies developing and/or validating multivariable prediction models for all-cause mortality in adults requiring or receiving veno-arterial (V-A) or veno-venous (V-V) ECMO. Estimates of model performance (observed versus expected (O:E) ratio and c-statistic) were summarized using random effects models and sources of heterogeneity were explored by means of meta-regression. Risk of bias was assessed using the Prediction model Risk Of BiAS Tool (PROBAST).

RESULTS

Among 4905 articles screened, 96 studies described a total of 58 models and 225 external validations. Out of all 58 models which were specifically developed for ECMO patients, 14 (24%) were ever externally validated. Discriminatory ability of frequently validated models developed for ECMO patients (i.e., SAVE and RESP score) was moderate on average (pooled c-statistics between 0.66 and 0.70), and comparable to general intensive care population-based models (pooled c-statistics varying between 0.66 and 0.69 for the Simplified Acute Physiology Score II (SAPS II), Acute Physiology and Chronic Health Evaluation II (APACHE II) score and Sequential Organ Failure Assessment (SOFA) score). Nearly all models tended to underestimate mortality with a pooled O:E > 1. There was a wide variability in reported performance measures of external validations, reflecting a large between-study heterogeneity. Only 1 of the 58 models met the generally accepted Prediction model Risk Of BiAS Tool criteria of good quality. Importantly, all predicted outcomes were conditional on the fact that ECMO support had already been initiated, thereby reducing their applicability for patient selection in clinical practice.

CONCLUSIONS

A large number of mortality prediction models have been developed for ECMO patients, yet only a minority has been externally validated. Furthermore, we observed only moderate predictive performance, large heterogeneity between-study populations and model performance, and poor methodological quality overall. Most importantly, current models are unsuitable to provide decision support for selecting individuals in whom initiation of ECMO would be most beneficial, as all models were developed in ECMO patients only and the decision to start ECMO had, therefore, already been made.

The feasibility of extracorporeal cardiopulmonary resuscitation for patients with active cancer who undergo in-hospital cardiac arrest

Indications of extracorporeal cardiopulmonary resuscitation (ECPR) are still debatable, particularly in patients with cancer. Prediction of the prognosis of in-hospital cardiac arrest (IHCA) in patients with cancer receiving ECPR is important given the increasing prevalence and survival rate of cancer. We compared the neurologic outcomes and survival rates of IHCA patients with and without cancer receiving ECPR. Data from the extracorporeal membrane oxygenation registry between 2015 and 2019 were used in a retrospective manner. The primary outcome was 6-month good neurologic outcome, defined as a Cerebral performance category score of 1 or 2. The secondary outcomes were 1- and 3-month good neurologic outcome, and 6-month survival. Among 247 IHCA patients with ECPR, 43 had active cancer. The 6-month good neurologic outcome rate was 27.9% and 32.4% in patients with and without active cancer, respectively (P > 0.05). Good neurologic outcomes at 1-month (30.2% vs. 20.6%) and 3-month (30.2% vs. 28.4%), and the survival rate at 6-month (39.5% vs. 36.5%) were not significantly different (all P > 0.05) Active cancer was not associated with 6-month good neurologic outcome by logistic regression analyses. Therefore, patients with IHCA should not be excluded from ECPR solely for the presence of cancer itself.

Extracorporeal cardiopulmonary resuscitation in-hospital cardiac arrest due to acute coronary syndrome

Background

The aim of this study was to analyze the effect of extracorporeal cardiopulmonary resuscitation on survival and neurological outcomes in in-hospital cardiac arrest patients.

Methods

Between January 2018 and December 2020, a total of 22 patients (17 males, 5 females; mean age: 52.8±9.0 years; range, 32 to 70 years) treated with extracorporeal cardiopulmonary resuscitation using veno-arterial extracorporeal membrane oxygenation support for in-hospital cardiac arrest after acute coronary syndrome were retrospectively analyzed. The patients were divided into two groups as those weaned (n=13) and non-weaned (n=9) from the veno-arterial extracorporeal membrane oxygenation. Demographic data of the patients, heart rhythms at the beginning of conventional cardiopulmonary resuscitation, the angiographic and interventional results, survival and neurological outcomes of the patients before and after extracorporeal cardiopulmonary resuscitation were recorded.

Results

There was no significant difference between the groups in terms of comorbidity and baseline laboratory test values. The underlying rhythm was ventricular fibrillation in 92% of the patients in the weaned group and there was no cardiac rhythm in 67% of the patients in the non-weaned group (p=0.125). The recovery in the mean left ventricular ejection fraction was significantly evident in the weaned group (36.5±12.7% vs. 21.1±7.4%, respectively; p=0.004). The overall wean rate from veno-arterial extracorporeal membrane oxygenation was 59.1%; however, the discharge rate from hospital of survivors without any neurological sequelae was 36.4%.

Conclusion

In-hospital cardiac arrest is a critical emergency situation requiring instantly life-saving interventions through conventional cardiopulmonary resuscitation. If it fails, extracorporeal cardiopulmonary resuscitation should be initiated, regardless the underlying etiology or rhythm disturbances. An effective conventional cardiopulmonary resuscitation is mandatory to prevent brain and body hypoperfusion.

The impact of selection criteria and study design on reported survival outcomes in extracorporeal oxygenation cardiopulmonary resuscitation (ECPR): a systematic review and meta-analysis

Background

The use of extracorporeal membrane oxygenation (ECMO) during cardiac arrest (ECPR) has increased exponentially. However, reported outcomes vary considerably due to differing study designs and selection criteria. This review assessed the impact of pre-defined selection criteria on ECPR survival.

Methods

Systematic review applying PRISMA guidelines. We searched Medline, Embase, and Evidence-Based Medicine Reviews for RCTs and observational studies published from January 2000 to June 2021. Adult patients (> 12 years) receiving ECPR were included. Two investigators reviewed and extracted data on study design, number and type of inclusion criteria. Study quality was assessed using the Newcastle–Ottawa Scale (NOS). Outcomes included overall and neurologically favourable survival. Meta-analysis and meta-regression were performed.

Results

67 studies were included: 14 prospective and 53 retrospective. No RCTs were identified at time of search. The number of inclusion criteria to select ECPR patients (p = 0.292) and study design (p = 0.962) was not associated with higher favourable neurological survival. However, amongst prospective studies, increased number of inclusion criteria was associated with improved outcomes in both OHCA and IHCA cohorts. (β = 0.12, p = 0.026) and arrest to ECMO flow time was predictive of survival. (β = -0.023, p < 0.001).

Conclusions

Prospective studies showed number of selection criteria and, in particular, arrest to ECMO time were associated with significant improved survival. Well-designed prospective studies assessing the relative importance of criteria as well as larger efficacy studies are required to ensure appropriate application of what is a costly intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13049-021-00956-5.

How effective is extracorporeal cardiopulmonary resuscitation (ECPR) for out-of-hospital cardiac arrest? A systematic review and meta-analysis

BACKGROUND

Extracorporeal cardiopulmonary resuscitation (ECPR) has gained increasing as a promising but resource-intensive intervention for out-of-hospital cardiac arrest (OHCA). There is little data to quantify the impact of this intervention and the patients likely to benefit from its use. We conducted a meta-analysis of the literature to assess the survival benefit associated with ECPR for OHCA.

METHODS

We searched PubMed, Embase, and Scopus databases to identify relevant observational studies and randomized control trials. We used the Newcastle-Ottawa Scale and Cochrane risk-of-bias tool to assess studies' quality. We performed random-effects meta-analysis for the primary outcome of survival to hospital discharge and used meta-regressions to assess heterogeneity.

RESULTS

We identified 1287 articles, reviewed the full text of 209 and included 44 in our meta-analysis. Our analysis included 3097 patients with OHCA. Patients' mean age was 52, 79% were male, and 60% had primary ventricular fibrillation/ventricular tachycardia arrest. We identified a survival-to-discharge rate of 24%; 18% survived with favorable neurologic function. 30- and 90-days survival rates were both around 18%. The majority of included articles were high quality studies.

CONCLUSIONS

Extracorporeal cardiopulmonary resuscitation is a promising but resource-intensive intervention that may increase rates of survival to hospital discharge among patients who experience OHCA.