Intra-Arrest Induction of Hypothermia via Large-Volume Ice-Cold Saline for Sudden Cardiac Arrest: The New York City Project Hypothermia Experience

Targeted temperature management and early neuro-prognostication after cardiac arrest

Targeted temperature management (TTM) is a recommended neuroprotective intervention for coma after out-of-hospital cardiac arrest (OHCA). However, controversies exist concerning the proper implementation and overall efficacy of post-CA TTM, particularly related to optimal timing and depth of TTM and cooling methods. A review of the literature finds that optimizing and individualizing TTM remains an open question requiring further clinical investigation. This paper will summarize the preclinical and clinical trial data to-date, current recommendations, and future directions of this therapy, including new cooling methods under investigation. For now, early induction, maintenance for at least 24 hours, and slow rewarming utilizing endovascular methods may be preferred. Moreover, timely and accurate neuro-prognostication is valuable for guiding ethical and cost-effective management of post-CA coma. Current evidence for early neuro-prognostication after TTM suggests that a combination of initial prediction models, biomarkers, neuroimaging, and electrophysiological methods is the optimal strategy in predicting neurological functional outcomes.

Characteristics Associated With Out-of-Hospital Cardiac Arrests and Resuscitations During the Novel Coronavirus Disease 2019 Pandemic in New York City

Question

What characteristics are associated with out-of-hospital cardiac arrests and death during the COVID-19 pandemic in New York City?

Findings

In this population-based cross-sectional study of 5325 patients with out-of-hospital cardiac arrests, the number undergoing resuscitation was 3-fold higher during the 2020 COVID-19 period compared with during the comparison period in 2019. Patients with out-of-hospital cardiac arrest during 2020 were older, less likely to be white, and more likely to have specific comorbidities and substantial reductions in return and sustained return of spontaneous circulation.

Meaning

Identifying patients at risk for out-of-hospital cardiac arrest and death during the COVID-19 pandemic should lead to interventions in the outpatient setting to help reduce out-of-hospital deaths.

Importance

Risk factors for out-of-hospital death due to novel coronavirus disease 2019 (COVID-19) are poorly defined. From March 1 to April 25, 2020, New York City, New York (NYC), reported 17 118 COVID-19–related deaths. On April 6, 2020, out-of-hospital cardiac arrests peaked at 305 cases, nearly a 10-fold increase from the prior year.

Objective

To describe the characteristics (race/ethnicity, comorbidities, and emergency medical services [EMS] response) associated with outpatient cardiac arrests and death during the COVID-19 pandemic in NYC.

Design, Setting, and Participants

This population-based, cross-sectional study compared patients with out-of-hospital cardiac arrest receiving resuscitation by the NYC 911 EMS system from March 1 to April 25, 2020, compared with March 1 to April 25, 2019. The NYC 911 EMS system serves more than 8.4 million people.

Exposures

The COVID-19 pandemic.

Main Outcomes and Measures

Characteristics associated with out-of-hospital arrests and the outcomes of out-of-hospital cardiac arrests.

Results

A total of 5325 patients were included in the main analysis (2935 men [56.2%]; mean [SD] age, 71 [18] years), 3989 in the COVID-19 period and 1336 in the comparison period. The incidence of nontraumatic out-of-hospital cardiac arrests in those who underwent EMS resuscitation in 2020 was 3 times the incidence in 2019 (47.5/100 000 vs 15.9/100 000). Patients with out-of-hospital cardiac arrest during 2020 were older (mean [SD] age, 72 [18] vs 68 [19] years), less likely to be white (611 of 2992 [20.4%] vs 382 of 1161 [32.9%]), and more likely to have hypertension (2134 of 3989 [53.5%] vs 611 of 1336 [45.7%]), diabetes (1424 of 3989 [35.7%] vs 348 of 1336 [26.0%]), and physical limitations (2259 of 3989 [56.6%] vs 634 of 1336 [47.5%]). Compared with 2019, the odds of asystole increased in the COVID-19 period (odds ratio [OR], 3.50; 95% CI, 2.53-4.84; P < .001), as did the odds of pulseless electrical activity (OR, 1.99; 95% CI, 1.31-3.02; P = .001). Compared with 2019, the COVID-19 period had substantial reductions in return of spontaneous circulation (ROSC) (727 of 3989 patients [18.2%] vs 463 of 1336 patients [34.7%], P < .001) and sustained ROSC (423 of 3989 patients [10.6%] vs 337 of 1336 patients [25.2%], P < .001), with fatality rates exceeding 90%. These associations remained statistically significant after adjustment for potential confounders (OR for ROSC, 0.59 [95% CI, 0.50-0.70; P < .001]; OR for sustained ROSC, 0.53 [95% CI, 0.43-0.64; P < .001]).

Conclusions and Relevance

In this population-based, cross-sectional study, out-of-hospital cardiac arrests and deaths during the COVID-19 pandemic significantly increased compared with the same period the previous year and were associated with older age, nonwhite race/ethnicity, hypertension, diabetes, physical limitations, and nonshockable presenting rhythms. Identifying patients with the greatest risk for out-of-hospital cardiac arrest and death during the COVID-19 pandemic should allow for early, targeted interventions in the outpatient setting that could lead to reductions in out-of-hospital deaths.

Impact of therapeutic hypothermia during cardiopulmonary resuscitation on neurologic outcome: A systematic review and meta-analysis

BACKGROUND

Therapeutic cooling initiated during cardiopulmonary resuscitation (intra arrest therapeutic hypothermia, IATH) provided diverging effect on neurological outcome of out-of-hospital cardiac arrest (OHCA) patients depending on the initial cardiac rhythm and the cooling methods used.

METHODS

We performed a systematic search of PubMed, EMBASE and the CENTRAL databases using established Medical Subject Headings (MeSH) terms for IATH and OHCA. Only studies comparing IATH to standard in-hospital targeted temperature management (TTM) were selected. We used the revised Cochrane RoB-2 and the Newcastle-Ottawa scale tool to assess risk of bias of each study. Primary outcome was favorable neurological outcome (FO); secondary outcomes included return of spontaneous circulation (ROSC) rate and survival to hospital discharge.

RESULTS

Out of 20,950 studies, 8 studies (n = 3493 patients, including 4 randomized trials, RCTs) were included in the final analysis. Compared to controls, the use of IATH was not associated with improved FO (OR 0.96 [95% CIs 0.68-1.37]; p = 0.84), increased ROSC rate (OR 1.11 [95% CIs 0.83-1.49]; p = 0.46) or survival (OR 0.91 [95% CIs 0.73-1.14]; p = 0.43). Significant heterogeneity among studies was observed for the analysis of ROSC rate (I² = 69%). Trans-nasal evaporative cooling and cold fluids were explored in two RCTs each and no differences were observed on FO, event when only patients with an initial shockable rhythm were analyzed (OR 1.62 [95% CI 1.00-2.64]; p = 0.05].

CONCLUSIONS

In this meta-analysis, IATH was not associated with improved neurological outcome when compared to standard in-hospital TTM, based on very low certainty of evidence.

CLINICAL TRIAL REGISTRATION

PROSPERO (CRD42019130322).

Fluid Therapy During Cardiopulmonary Resuscitation

Cardiopulmonary arrest (CPA), the acute cessation of blood flow and ventilation, is fatal if left untreated. Cardiopulmonary resuscitation (CPR) is targeted at restoring oxygen delivery to tissues to mitigate ischemic injury and to provide energy substrate to the tissues in order to achieve return of spontaneous circulation (ROSC). In addition to basic life support (BLS), targeted at replacing the mechanical aspects of circulation and ventilation, adjunctive advanced life support (ALS) interventions, such as intravenous fluid therapy, can improve the likelihood of ROSC depending on the specific characteristics of the patient. In hypovolemic patients with CPA, intravenous fluid boluses to improve preload and cardiac output are likely beneficial, and the use of hypertonic saline may confer additional neuroprotective effects. However, in euvolemic patients, isotonic or hypertonic crystalloid boluses may be detrimental due to decreased tissue blood flow caused by compromised tissue perfusion pressures. Synthetic colloids have not been shown to be beneficial in patients in CPA, and given their documented potential for harm, they are not recommended. Patients with documented electrolyte abnormalities such as hypokalemia or hyperkalemia benefit from therapy targeted at those disturbances, and patients with CPA induced by lipid soluble toxins may benefit from intravenous lipid emulsion therapy. Patients with prolonged CPA that have developed significant acidemia may benefit from intravenous buffer therapy, but patients with acute CPA may be harmed by buffers. In general, ALS fluid therapies should be used only if specific indications are present in the individual patient.

The impact of intra-arrest hypothermia

PURPOSE OF REVIEW

To address the impact of therapeutic hypothermia induced already during cardiopulmonary resuscitation (i.e. intra-arrest cooling) and its association with neurologic functional outcome.

RECENT FINDINGS

Intra-arrest cooling is superior than post-ROSC cooling to mitigate brain injuries in experimental models of cardiac arrest. The delayed initiation of hypothermia in human studies may not have adequately addressed the underlying pathophysiology of ischemia and reperfusion. The assessment of early initiation of cooling has been complicated by increased rate of hemodynamic adverse events caused by infusion of cold intravenous fluids. These adverse events have been more deleterious in patients with initial shockable rhythms. A recent randomized study shows that an alternative intra-arrest cooling method using trans-nasal evaporative cooling was well tolerated and effective to shorten time to target temperature. However, the neurologic outcomes (CPC 1-2 at 90 days) in favor of intra-arrest cooling compared to hospital cooling (34.8% vs 25.9%, P = 0.11) in patients with initial shockable rhythms did not reach statistical significance.

SUMMARY

Therapeutic intra-arrest hypothermia can be initiated safely at the scene of the arrest using transnasal evaporative cooling. The potential beneficial effect of intra-arrest cooling on neurologic recovery in patients with initial shockable rhythms should be explored further.

Outcomes of Veno-Arterial Extracorporeal Membrane Oxygenation for In-Hospital Cardiac Arrest

Veno-arterial extracorporeal membrane oxygenation (VA ECMO) is increasingly used in cardiac arrest. Currently, public registries report the outcomes of cardiac arrest regardless of the setting (out-of-hospital versus in-hospital). Meanwhile, in-hospital cardiac arrest represents a more favorable setting for ECMO-assisted cardiopulmonary resuscitation than out-of-hospital cardiac arrest. Survival to discharge varies, but looks promising overall, ranging from 18.9 to 65%, with the bulk of the studies reporting survival to discharge between 30% and 50%, with about one-third to half of the patients discharged with no or minimal neurologic deficit. Based on the reported outcomes, in-hospital cardiac arrests can become a next focus for studies on successful implementation of VA ECMO.