Extracorporeal Cardiopulmonary Resuscitation in Hypothermic Cardiac Arrest: A Secondary Analysis of Multicenter Extracorporeal Cardiopulmonary Resuscitation Registry Data in Japan

doi:10.21203/rs.3.rs-3236474/v1

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Extracorporeal Cardiopulmonary Resuscitation in Hypothermic Cardiac Arrest: A Secondary Analysis of Multicenter Extracorporeal Cardiopulmonary Resuscitation Registry Data in Japan

https://doi.org/10.21203/rs.3.rs-3236474/v1

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published 01 Sep, 2024

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Background

Extracorporeal cardiopulmonary resuscitation (ECPR) is used to resuscitate patients with cardiac arrest; however, its effectiveness in treating hypothermic cardiac arrest has not been well studied. Therefore, this study aimed to examine the characteristics and outcomes of patients with hypothermic cardiac arrest who underwent ECPR using a multicenter out-of-hospital cardiac arrest (OHCA) registry in Japan.

Methods

Patients with hypothermic OHCA with body temperature below 32°C were identified, and their baseline characteristics were assessed. Logistic regression analysis was performed to identify factors associated with in-hospital mortality and neurological outcomes in patients with hypothermic OHCA. A comparison of outcomes between hypothermic and cardiogenic OHCA cases was also conducted using propensity score matching to investigate differences among subgroups.

Results

We included 2,157 patients, with 102 and 1,644 in the hypothermia and cardiogenic groups, respectively. In the multivariate logistic analysis, age (odds ratio [OR], 1.05; p < 0.01) and estimated low-flow time (OR, 1.02; p = 0.04) were independent risk factors for mortality, and age (OR, 1.06; p < 0.01) was an independent risk factor for unfavorable neurological outcomes in hypothermic OHCA. In the propensity score matching analysis, 62 matched pairs were selected, and the mortality rate was lower in the hypothermic group than in the cardiogenic group (46.8% vs. 83.9%, p < 0.01). Additionally, the rate of unfavorable neurological outcomes was lower in the hypothermic group than in the cardiogenic group (64.5% vs. 95.2%, p < 0.01).

Conclusions

Increased age and prolonged duration of low-flow time were identified as negative prognostic factors in patients with hypothermic OHCA who underwent ECPR. Moreover, patients with hypothermic OHCA showed lower mortality and unfavorable neurological outcome rates than patients with cardiogenic OHCA, suggesting that ECPR is a promising strategy for treating patients with hypothermic OHCA.

Cardiopulmonary resuscitation

Extracorporeal Circulation

Out-of-hospital cardiac arrest

Hypothermia

Outcome

Survival rate

Accidental hypothermia (AH) is a medical emergency and potentially life-threatening condition [1]. Severe AH can trigger fatal arrhythmias, such as ventricular fibrillation (VF), which can lead to cardiac arrest. Therefore, prompt and appropriate intervention is critical to improve a patient’s chances of survival. Thus, in addition to immediate cardiopulmonary resuscitation (CPR), rewarming should be initiated in patients with AH. Various external rewarming techniques, including passive and active methods and invasive measures, such as warmed intravenous fluids or catheter-based heat exchange systems, have been used to achieve successful resuscitation [2].

Simultaneously, extracorporeal membrane oxygenation (ECMO) can provide circulatory support and rewarm using a heat exchanger. The European Resuscitation Council guidelines recommend the use of ECMO in patients with cardiac arrest or circulatory instability due to AH [3]. Therefore, extracorporeal cardiopulmonary resuscitation (ECPR) combined with ECMO may be a promising therapeutic strategy for patients with cardiac arrest and severe hypothermia [4]. However, evidence regarding the effectiveness of rewarming with ECMO in patients with severe AH is limited, primarily due to the rarity of eligible patients [3]. A recent multicenter observational study suggested that ECPR improves survival and neurological outcomes in patients with AH and cardiac arrest [4]. However, this study included a limited number of patients with hypothermic cardiac arrest; thus, additional studies are warranted to provide definitive evidence [4]. Therefore, we aimed to evaluate the effectiveness of ECPR in a larger population of patients with out-of-hospital cardiac arrest (OHCA) due to hypothermia by utilizing data from a large ECPR registry of patients with cardiac arrest due to AH.

Study setting and design

We conducted a secondary analysis of the Advanced Life Support for VF with Extracorporeal Circulation in Japan (SAVE-J II) registry. The SAVE-J II registry includes data on initial cardiac rhythm, age, time (low-flow or no-flow), and outcomes of patients with OHCA who underwent ECPR at 36 hospitals in Japan between January 1, 2013, and December 31, 2018 [5].

Patient and public involvement

This study did not include patient and public involvement.

Study population

We selected patients with OHCA from the SAVE-J II registry who met the inclusion criteria for hypothermic and cardiogenic cardiac arrest. Hypothermic cardiac arrest was defined by a body temperature (BT) ≤ 32°C on admission to the emergency department. Patients without cardiac or hypothermic conditions were excluded. Additionally, patients who achieved a return of spontaneous circulation (ROSC) upon hospital arrival and ECMO initiation were excluded, along with those missing data on outcomes or BT.

Data collection

The following patient variables were collected from the SAVE-J II registry: age, sex, comorbidities, BT upon hospital arrival, Cerebral Performance Category (CPC) score, the incidence of witnessed cardiac arrest, bystander CPR, an initial cardiac rhythm at the scene, cardiac arrest location, use of defibrillation, prehospital airway management, cardiac rhythm before ECMO initiation, time course, cause of cardiac arrest, ROSC after hospital arrival, and ECMO information. Furthermore, the initial shockable rhythm was defined as VF, pulseless ventricular tachycardia, or rhythm for defibrillation in an automated external defibrillator used by emergency medical staff [5]. Evaluated comorbidities comprised heart disease, cerebrovascular disease, and chronic kidney disease. ROSC was defined as at least 1 min of continuing confirmation of pulsation. The estimated low-flow time was defined as the time from cardiac arrest to the establishment of ECMO, if the location of cardiac arrest was an ambulance, and the time from finding the patient to the establishment of ECMO, if the location of cardiac arrest was other than an ambulance. Data on the complications during ECPR were also collected. A favorable neurological outcome was defined as a CPC score of 1 or 2, whereas an unfavorable outcome was defined as a CPC score of 3–5.

Missing value imputation

After selecting the study cohort, missing values were imputed using patient characteristics (age and sex), outcomes, and other covariates, including initial rhythm during cardiac arrest and location of cardiac arrest, using the random forest method for each study cohort with the missForest package (version 1.4) in R software (version 3.5.2; R Foundation for Statistical Computing, Vienna, Austria) [6].

Outcome measures

The primary outcome of this study was the mortality rate at hospital discharge. Secondary outcomes included unfavorable neurological outcomes based on the CPC.

Statistical analysis

Baseline characteristics and outcomes were summarized using descriptive statistics. Categorical variables are presented as proportions. Continuous variables are presented as medians and interquartile ranges (IQRs). Multivariate logistic regression analyses were performed to determine factors related to mortality and unfavorable neurological outcomes at hospital discharge. In multivariate models, we adjusted for age, sex, comorbidities, bystander CPR, and estimated low-flow time. We compared baseline characteristics, mortality, and CPC at hospital discharge between hypothermic and cardiogenic groups using the Mann–Whitney U test for continuous variables and Fisher’s exact or chi-square test for categorical variables, as appropriate. Considering the unbalanced characteristics of hypothermic and cardiogenic groups, we used propensity score matching analysis to compare the outcomes. A logistic regression model was applied to estimate the propensity score for each patient, predicting mortality based on age, sex, comorbidities, bystander CPR, and estimated low-flow time. The propensity score matching extracted 1:1 matched pairs of patients with hypothermic and cardiogenic cardiac arrest. Matched pairs from the two groups were assessed using the absolute standardized mean difference. Values < 0.01 were considered acceptable. All statistical analyses were performed using EZR, a modified version of the R commander designed to add statistical functions frequently used in biostatistics [7].

Hypothermia outcome prediction after extracorporeal life support (HOPE) survival probability

The HOPE score provides an estimate of the probability of in-hospital survival of a patient with cardiac arrest with AH after extracorporeal life support (ECLS) rewarming, based on the following six covariates available at hospital admission: age, sex, mechanism of hypothermia, core temperature (if not available, prehospital temperature), serum potassium level, and CPR duration (defined as the time from the initiation of CPR to the start of ECLS) [8]. The HOPE score for each patient was calculated as described in a previous study [9].

Study participants

A flow diagram of the patient selection process is illustrated in Figure 1. Among the 2,157 adult patients with OHCA who received ECPR in the SAVE-J II registry, a total of 1,748 patients were eligible for analysis. Of these, 102 and 1,644 patients had hypothermic and cardiogenic cardiac arrests, respectively.

Baseline characteristics of the hypothermic group

Characteristics of the patients in the hypothermic group are presented in Table 1. Briefly, their median [IQR] age was 68 [56–78] years; additionally, 65.7% were male, 46.1% had witnessed cardiac arrest, and 46.1% had received bystander CPR. Regarding prehospital intervention, 49% of the patients were defibrillated. The OHCA location is also listed in Table 1; the most common location was home (35.2%). The proportions of initial cardiac rhythms at the scene were 45.1%, 26.4%, and 27.4% for VF, pulseless electrical activity, and asystole, respectively. The BT median was 24.2℃ [22.4–26.5]. The median time from the call for an ambulance to ECMO was 73 [56–88] min, and the median estimated low-flow time was 69 [51.7–83.5] min. A histogram of the relationship between BT, number of survivors, and mortality cases is illustrated in Figure 2. In-hospital mortality rates tended to increase with BT below 28℃.

Table 1 Patient characteristics according to their hospital outcomes
Variables	Total (n=102)
Age, years, median (IQR)	68 [56–78]
Sex, n (%)
Female	35 (34.3)
Male	67 (65.7)
BT on hospital arrival, Celsius, median (IQR)	24.2 [22.4–26.5]
Swiss clinical staging of hypothermia, n (%)
Hypothermia Ⅰ 35-32	0 (0)
Hypothermia Ⅱ 32-28	11 (10.7)
Hypothermia Ⅲ 28-24	48 (47)
Hypothermia Ⅳ <24	43 (42.1)
Comorbidities, n (%) ^※
Heart disease	8 (7.8)
Cerebrovascular disease	11 (10)
Chronic kidney disease	4 (3.9)
Location of cardiac arrest, n (%)
Home	36 (35.2)
Public place	14 (13.7)
Street	12 (11.7)
Ambulance	18 (17.6)
Workplace	0 (0)
Other	23 (22.5)
Initial cardiac rhythm at the scene
Ventricular fibrillation, n (%)	46 (45.1)
Pulseless electrical activity, n (%)	27 (26.4)
Asystole, n (%)	28 (27.4)
Witnessed cardiac arrest, n (%)	47 (46.1)
Bystander CPR, n (%)	47 (46.1)
Prehospital intervention
Defibrillation, n (%)	50 (49)
ROSC before hospital arrival, n (%)	2 (1.9)
Initial cardiac rhythm on hospital arrival
Ventricular fibrillation, n (%)	54 (52.9)
Pulseless electrical activity, n (%)	19 (18.6)
Asystole, n (%)	28 (27.5)
Time course, minutes, median (IQR)
Time from arrival to ECMO	28 [17–43.7]
Time from call for ambulance to ECMO	73 [56–88]
Estimated low-flow time	69 [51.7–83.5]
Complications during ECPR, n (%)
Cannula malposition	8 (7.8)
Unsuccessful cannulation	0 (0)
Cannulation-related bleeding	10 (9.8)
Other	1 (0.9)
Hemorrhage	2 (1.9)
Ischemia	0 (0)
In-hospital mortality, n (%)	53 (51.9)
Neurological outcome at discharge, unfavorable, n (%)	71 (69.9)
IQR, interquartile range; BT, body temperature; CPR, cardiopulmonary resuscitation; ROSC, return of spontaneous circulation; ECMO, extracorporeal membrane oxygenation; ECPR, extracorporeal cardiopulmonary resuscitation

Risk factors for mortality and unfavorable neurological outcome in patients with hypothermic cardiac arrest

In the multivariate logistic regression analysis, age (odds ratio [OR], 1.05; p < 0.01) and estimated low-flow time (OR, 1.02 per minute; p=0.04) were independent risk factors for in-hospital mortality in the hypothermic group (Table 2). Additionally, multivariate logistic regression analysis, to assess unfavorable neurological outcomes, revealed a significant association with age (OR, 1.06; p < 0.01) (Table 3).

Table 2 Multivariable logistic regression analysis of mortality
Variables	OR (95% CI)	P-value
Age	1.05 (1.01–1.09)	< 0.01
BT on hospital arrival	1.05 (0.88–1.23)	0.59
Male	1.12 (0.38–3.27)	0.83
Presence of one or more comorbidities^※	1.16 (0.35–3.79)	0.8
Bystander CPR	0.84 (0.31–2.3)	0.74
Estimated low-flow time	1.02 (1–1.03)	0.04
OR, odds ratio; CI, confidence interval; BT, body temperature; CPR, cardiopulmonary resuscitation
^※Comorbidities: heart disease, cerebrovascular disease, chronic kidney disease

Table 3 Multivariable logistic regression analysis of unfavorable neurological outcomes at discharge
Variables	OR (95% CI)	P-value
Age	1.06 (1.02–1.9)	< 0.01
BT on hospital arrival	1.01 (0.85-1.20)	0.96
Male	1.51 (0.48–4.75)	0.47
Presence of one or more comorbidities^※	2.3 (0.55–9.57)	0.25
Bystander CPR	0.71 (0.24–2.06)	0.53
Estimated low-flow time	1.01(0.99-1.02)	0.36
OR, odds ratio; CI, confidence interval; BT, body temperature; CPR, cardiopulmonary resuscitation
^※Comorbidities; heart disease, cerebrovascular disease, chronic kidney disease

Comparison of outcomes between hypothermic and cardiogenic groups

Baseline characteristics of the study cohort are presented in Table 4. The hypothermic group had a higher median age than the cardiogenic group. Moreover, the prevalence of VF was higher in the cardiogenic group than in the hypothermic group. However, despite longer low-flow times, the hypothermia group had lower mortality and unfavorable neurological outcomes than the cardiogenic group.

Table 4 Characteristics of patients before propensity score matching
Variable	Cardiogenic (n=1644)	Hypothermic (n=102)	SMD	P-value
Age, years old, median (IQR)	60 [49–68]	68 [56–78]	0.5	< 0.01
Sex, male, n (%)	1390 (84.6)	67(65.7)	0.44	< 0.01
Presence of one or more comorbidities, n (%)	1135 (72.6)	77 (75.4)	0.27	0.01
BT on hospital arrival, Celsius, median (IQR)	35.2 [34.2–35.9]	24.2 [22.4–26.5]	4.3	< 0.01
Place of event, outdoor, n (%)	232 (14.2)	12 (11.7)	0.08	0.56
Presence of one or more comorbidities^※, n (%)	516 (31.4)	19 (18.6)	0.29	< 0.01
Initial cardiac rhythm, n (%)
Ventricular fibrillation	1096 (67.3)	46(45.1)	0.44	< 0.01
Ventricular tachycardia	34 (2.1)	0 (0)	0.21	0.26
Pulseless electrical activity	368 (22.6)	27 (26.4)	0.46	0.08
Asystole	130 (8.0)	28 (27.4)	0.54	< 0.01
Bystander CPR, n (%)	945 (58.2)	47 (46.1)	0.23	0.02
Witness, n (%)	1289 (78.7)	47 (46.1)	0.71	< 0.01
In-hospital mortality, n (%)	1197 (72.8)	53 (51.9)	0.43	< 0.01
Complications during ECPR, n (%)
Cannula malposition	81 (4.9)	8 (7.8)	0.12	0.28
Unsuccessful cannulation	11 (0.7)	0 (0)	0.12	1
Cannulation-related bleeding	268 (16.3)	10 (9.8)	0.19	0.09
Other	26 (1.6)	1 (0.9)	0.05	1
Hemorrhage	139 (8.5)	2 (1.9)	0.29	0.01
Ischemia	26 (1.6)	0	0.18	0.4
Neurological outcome at discharge, unfavorable, n (%)	1413 (85.9)	71 (69.9)	0.4	< 0.01
Estimated low-flow time, minutes, median (IQR)	55 [45–66]	69 [51.7–83.5]	0.58	< 0.01
Time from call for ambulance to ECMO, minutes, median (IQR)	56 [47–68]	73 [56–88]	0.68	< 0.01
Length of hospital stay, days, median (IQR)	3 [1–19]	9 [2–39]	0.24	0.01
IQR, interquartile range; SMD, standardized mean difference; BT, body temperature; CPR, cardiopulmonary resuscitation; ECPR, extracorporeal cardiopulmonary resuscitation; ECMO, extracorporeal membrane oxygenation
^※Comorbidities: heart disease, cerebrovascular disease, chronic kidney disease

Based on propensity score matching analysis, 62 matched pairs were selected using a one-to-one matching process. The major baseline characteristics of patients in the propensity score-matched cohort are presented in Table 5. The mortality rate and unfavorable neurological outcomes were lower in the hypothermic group than in the cardiogenic group (46.8% vs. 83.9%; p < 0.01), (64.5% vs. 95.2%; p < 0.01), respectively.

Table 5 Characteristics of patients after propensity score matching
Variable	Cardiogenic (n=62)	Hypothermic (n=62)	SMD	P-value
Age, years old, median (IQR)	64.5 [54.2–70.7]	64.5 [55.0–71.7]	< 0.01	0.98
Gender, male, n (%)	53 (85.5)	53 (85.5)	< 0.01	1
Presence of one or more comorbidities^※, n (%)	13 (21.0)	13 (21.0)	< 0.01	1
BT on hospital arrival, Celsius, median (IQR)	35.1 [34.2–35.8]	24.4 [22.5–26.7]	4.3	< 0.01
Place of event, outdoor, n (%)	14 (22.6)	8 (12.9)	0.25	0.24
Initial cardiac rhythm, n (%)
Ventricular fibrillation	46 (75.4)	30 (50)	0.54	< 0.01
Ventricular tachycardia	2 (3.3)	0 (0)	0.26	0.49
Pulseless electrical activity	8 (13.1)	15 (25)	0.31	0.11
Asystole	5 (8.2)	15 (25)	0.46	0.01
Bystander CPR, n (%)	29 (46.8)	29 (46.8)	< 0.01	1
Witness, n (%)	47 (75.8)	29 (46.8)	0.624	< 0.01
In-hospital mortality, n (%)	52 (83.9)	29 (46.8)	0.84	< 0.01
Complications during ECPR, n (%)
Cannula malposition	1 (1.6)	3 (4.8)	0.17	0.62
Unsuccessful cannulation	0 (0)	0(0)	< 0.01	NA
Cannulation-related bleeding	10 (16.1)	6 (9.6)	0.18	0.43
Other	0(0)	0 (0)	< 0.01	NA
Hemorrhage	3 (4.8)	1 (1.6)	0.17	0.62
Ischemia	0 (0)	0 (0)	< 0.01	NA
Neurological outcome at discharge, unfavorable, n (%)	59.0 (95.2)	40.0 (64.5)	0.82	< 0.01
Estimated low-flow time, minute, median (IQR)	63 [49.2–76.0]	63 [49.7–76.7]	< 0.01	0.99
Time from call for ambulance to ECMO, minute, median (IQR)	65 [52.5–78.5]	59 [43.0–72.2]	0.95	0.21
Length of hospital stay, days, median (IQR)	2 [1.0–4.75]	14 [2.0–39.0]	0.54	< 0.01
IQR, interquartile range; SMD, standardized mean difference; BT, body temperature; CPR, cardiopulmonary resuscitation; ECPR, extracorporeal cardiopulmonary resuscitation; ECMO, extracorporeal membrane oxygenation
Comorbidities: heart disease, cerebrovascular disease, chronic kidney disease

HOPE survival probability score

Boxplots of HOPE survival probabilities estimated in the 88 patients are illustrated in Supplemental Figure S1. The HOPE survival probability was lower in the mortality group than in the survival group (0.45 [0.17–0.69] and 0.57 [0.41–0.77], respectively; p=0.03). The area under the curve was 0.636 (95% confidence interval: 0.519–0.753) (Supplemental Figure S1).

The present study identified older age and prolonged duration of low-flow time as significant predictors of mortality in patients who underwent ECPR during hypothermic cardiac arrest. Furthermore, patients with hypothermic cardiac arrest exhibited lower mortality rates and unfavorable neurological outcomes compared to patients with cardiogenic cardiac arrest.

AH involves an unintentional decrease in core BT below 35℃ [1]. Therefore, in moderate-to-severe hypothermia with BT less than 32℃, the risk of arrhythmia and cardiac arrest increases [1]. A recent nationwide study of AH in Japan indicated that 21% of patients with AH had severe hypothermia, with a mortality rate as high as 29% [10]. Veno-arterial ECMO has several pathophysiological advantages over other rewarming methods. Specifically, it is the fastest method for rewarming, provides adequate and immediate circulatory support, rapidly corrects metabolic and electrolyte derangements, and rewarms the heart before the rest of the body, preventing shock from peripheral vasodilatation [11, 12].

Several previous studies have reported beneficial outcomes of using ECMO for hypothermia treatment [3, 4, 12]. However, these studies either included mixed conventional CPR and ECMO cases or had limited ECMO-only cases. Moreover, only a few studies examined large numbers of ECMO-only cases. In contrast, in the present study, we performed extensive analyses of a relatively large number of patients with AH undergoing ECPR. We identified age and estimated low-flow time as factors influencing the mortality rate after ECPR. Neither temperature nor initial cardiac rhythm was significantly associated with the prognosis in the present study. Furthermore, previous studies support our finding that the core temperature is not associated with in-hospital mortality [13, 14]. The present study, along with previous literature [3, 4, 12], also demonstrates that ECMO may prove beneficial in hypothermic cardiac arrest cases. However, the optimal timing for its initiation and the specific indicated cases have not yet been thoroughly investigated. Therefore, further research is required to address these issues.

Hypothermia increases the tolerance of the brain to ischemia by slowing down metabolic processes and reducing oxygen consumption [11]. To the best of our knowledge, this is the first study to demonstrate that the use of ECMO for hypothermic cardiac arrest is associated with lower mortality rates and unfavorable neurological outcomes compared to those in its use for cardiogenic cardiac arrest. Although there are no definitive criteria, it is prudent to use ECPR more aggressively for hypothermic cardiac arrest than for cardiogenic cardiac arrest.

Moreover, because ECMO is an invasive treatment with more complications than conventional CPR, it is necessary to strictly select patients for whom ECMO is indicated. ECMO-related complications include bleeding, unsuccessful cannulation, infection, ischemia, and hemolysis [15–17]. Among ECPR-related complications, the most common is bleeding, with rates ranging between 8–70% in previous studies [18, 19]. Hypothermia decreases platelet function and clotting factor activity, resulting in abnormal coagulation [20]. However, in our study, patients with hypothermic cardiac arrest did not show a higher rate of bleeding complication than patients with cardiogenic cardiac arrest (9.8% vs. 16.3%; p = 0.09). This result persisted even with propensity score matching (9.6% vs. 16.1%, p = 0.43). The lack of a uniform definition of hemorrhagic complications across institutions and differences in patient body mass index compared to those in Western countries may have influenced the results. However, the findings of the present study suggest that is no need to hesitate to use ECPR in cases of hypothermic cardiac arrest due to concerns about the bleeding risk.

The HOPE score has been reported to predict survival outcomes in patients with AH who undergo ECMO. Consistent with this, the HOPE scores tended to be lower in cases of mortality in the present study; however, the area under the curve was not sufficiently high, thus, its usefulness is debatable. Possible reasons for the low accuracy of HOPE predictions in the present study are as follows. First, the patient background differed from that in the original article on HOPE as most participants in the present study were elderly (median age, 35 vs. 68 years). Second, the location of hypothermia and the circumstances leading to its discovery differed. The above-mentioned reports mostly comprised younger populations who experienced cardiac arrest associated while performing outdoor activities, such as skiing or climbing, in winter [11]. In contrast, in a super-aging society, such as Japan, most patients with AH are elderly and frail and experienced cardiac arrest in indoor settings [21]. Therefore, it is desirable to have appropriate ECMO introduction criteria and methods for predicting outcomes tailored to each country’s climate and population distribution.

Limitations

The present study had some limitations. First, this was a retrospective study with variations in the inclusion criteria across participating institutions. Second, although the cause of AH was considered a prognostic factor [11], the cause of hypothermia was not investigated in the present study. Third, no predominant results were found for the prognostic score; however, owing to missing data, this was only a reference interpretation. Fourth, there was no control group. Ideally, to assess the utility of ECPR for hypothermia, hypothermic cardiac arrest cases treated with ECPR should be compared to those treated with conventional CPR. However, this was impossible because we utilized data from an OHCA registry. Conversely, compared to the ICE-CRASH study [4] and other studies, the present study analyzed more ECPR cases, enabling us to examine detailed background factors and prognostic determinants. Finally, confounders of the time course, such as the number of ROSCs and total ROSC time until ECMO establishment, could not be obtained from this dataset. Thus, the estimated low-flow time may differ from the actual low-flow time.

In this large cohort study, we comprehensively examined the epidemiological characteristics of patients with hypothermia undergoing ECPR and demonstrated that age and estimated low-flow time significantly influenced patient outcomes. Among patients receiving ECPR, those with hypothermic cardiac arrest have a better prognosis than those with cardiogenic cardiac arrest. Overall, these results suggest that ECPR is a promising strategy for managing patients with hypothermic cardiac arrest.

Ethics approval and consent to participate

All studies using the SAVE-J Ⅱregistry were conducted in accordance with the principles outlined in the Declaration of Helsinki. This study approved and the requirement for patient consent was waived at all participating institutions because of the retrospective nature of this study by the institutional review board of Kagawa University (approval number: 2018-110) and each participating institution.

Consent for publication

Not applicable. No personally identifiable information or photos.

Data availability

Please contact the author for data requests.

Competing interests

The authors declare that they have no competing interests.

Funding

This study was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (Grant-in-Aid for Scientific Research [C]), Grant Number JP19K09419.

Author contributions

ST and MK carried out data collection. ST, MK, and T. Shoko performed data analysis. ST, AI, TH, T. Sakamoto, and YK conceived the study, and ST, MK, T. Sakamoto, AI, TH, T. Shoko, and YK participated in its design and coordination. ST, and MK, drafted the manuscript. All authors read and approved the final manuscript.

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No competing interests reported.

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published 01 Sep, 2024

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Extracorporeal Cardiopulmonary Resuscitation in Hypothermic Cardiac Arrest: A Secondary Analysis of Multicenter Extracorporeal Cardiopulmonary Resuscitation Registry Data in Japan

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Abstract

Background

Methods

Results

Conclusions

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BACKGROUND

METHODS

Study setting and design

Patient and public involvement

Study population

Data collection

Missing value imputation

Outcome measures

Statistical analysis

Hypothermia outcome prediction after extracorporeal life support (HOPE) survival probability

RESULTS

DISCUSSION

Limitations

Conclusions

Declarations

References

Additional Declarations

Supplementary Files

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Journal Publication

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