Prognostic impact of the conversion to a shockable rhythm from a non-shockable rhythm for patients suffering from out-of-hospital cardiac arrest.

OBJECTIVE: For patients suffering from an out-of-hospital cardiac arrest (OHCA), having an initial shockable rhythm is a marker of good prognosis. It has been suggested as one of the main prognosticating factors for the selection of patients for extracorporeal resuscitation (E-CPR). However, the prognostic implication of converting from a non-shockable to a shockable rhythm, as compared to having an initial shockable rhythm, remains uncertain, especially among patients that can otherwise be considered eligible for E-CPR. The objective of this study was to evaluate the association between the initial rhythm and its subsequent conversion and survival following an OHCA, for the general population and for E-CPR candidates. METHODS: This study used a registry of OHCA in Montreal, Canada. Adult patients suffering from a non-traumatic OHCA for whom the initial rhythm was known were included. The association between the initial rhythm and its subsequent conversion or not and survival to discharge was assessed using a multivariable logistic regression. RESULTS: Of 6681 included patients, 1788 (27%) had an initial shockable rhythm, 1749 (26%) had pulseless electrical activity (PEA) and no subsequent shockable rhythm, 295 (4%) had PEA and a subsequent shockable rhythm, 2694 (40%) had asystole and no subsequent shockable rhythm, and 155 (2%) asystole and a subsequent shockable rhythm. As compared to patients having an initial shockable rhythm, patients in all other groups had significantly lower odds of survival to hospital discharge (p < 0.001 for all comparisons). Univariate analyses were performed for E-CPR candidates. Among these 556 (8%) patients, more patients with an initial shockable rhythm survived than patients in all other groups (p < 0.001 for all comparisons). CONCLUSIONS: The initial rhythm remains a much better prognostic marker than subsequent rhythms for all patients suffering from an OHCA, including in the subset of potential E-CPR candidates.

The prognostic significance of repeated prehospital shocks for out-of-hospital cardiac arrest survival.

OBJECTIVES: Patients suffering from an out-of-hospital cardiac arrest (OHCA) associated with an initial shockable rhythm have a better prognosis than their counterparts. The implications of recurrent or refractory malignant arrhythmia in such context remain unclear. The objective of this study is to evaluate the association between the number of prehospital shocks delivered and survival to hospital discharge among patients in OHCA. METHODS: This cohort study included adult patients with an initial shockable rhythm over a 5-year period from a registry of OHCA in Montreal, Canada. The relationship between the number of prehospital shocks delivered and survival to discharge was described using dynamic probabilities. The association between the number of prehospital shocks delivered and survival to discharge was assessed using multivariable logistic regression. RESULTS: A total of 1,788 patients (78% male with a mean age of 64 years) were included in this analysis, of whom 536 (30%) received treatments from an advanced care paramedic. A third of the cohort (583 patients, 33%) survived to hospital discharge. The probability of survival was highest with the first shock (33% [95% confidence interval 30%-35%]), but decreased to 8% (95% confidence interval 4%-13%) following nine shocks. A higher number of prehospital shocks was independently associated with lower odds of survival (adjusted odds ratio=0.88 [95% confidence interval 0.85-0.92], p < 0.001). CONCLUSION: Survival remains possible even after a high number of shocks for patients suffering from an OHCA with an initial shockable rhythm. However, requiring more shocks is independently associated with worse survival.

Impact of the direct transfer to percutaneous coronary intervention-capable hospitals on survival to hospital discharge for patients with out-of-hospital cardiac arrest.

AIMS: Patients suffering from out-of-hospital cardiac arrest (OHCA) are frequently transported to the closest hospital. Percutaneous coronary intervention (PCI) is often indicated following OHCA. This study's primary objective was to determine the association between being transported to a PCI-capable hospital and survival to discharge for patients with OHCA. The additional delay to hospital arrival which could offset a potential increase in survival associated with being transported to a PCI-capable center was also evaluated. METHODS: This study used a registry of OHCA in Montreal, Canada. Adult patients transported to a hospital following a non-traumatic OHCA were included. Hospitals were dichotomized based on whether PCI was available on-site or not. The effect of hospital type on survival to discharge was assessed using a multivariable logistic regression. The added prehospital delay which could offset the increase in survival associated with being transported to a PCI-capable center was calculated using that regression. RESULTS: A total of 4922 patients were included, of whom 2389 (48%) were transported to a PCI-capable hospital and 2533 (52%) to a non-PCI-capable hospital. There was an association between being transported to a PCI-capable center and survival to discharge (adjusted odds ratio = 1.60 [95% confidence interval 1.25-2.05], p < .001). Increasing the delay from call to hospital arrival by 14.0 min would offset the potential benefit of being transported to a PCI-capable center. CONCLUSIONS: It could be advantageous to redirect patients suffering from OHCA patients to PCI-capable centers if the resulting expected delay is of less than 14 min.

Potential impact of a prehospital redirection system for refractory cardiac arrest.

AIM: A change in prehospital redirection practice could potentially increase the proportion of E-CPR eligible patients with out-of-hospital cardiac arrest (OHCA) transported to extracorporeal cardiopulmonary resuscitation (E-CPR) capable centers. The objective of this study was to quantify this potential increase of E-CPR candidates transported to E-CPR capable centers. METHODS: Adults with non-traumatic OHCA refractory to 15min of resuscitation were selected from a registry of adult OHCA collected between 2010 and 2015 in Montreal, Canada. Using this cohort, three simulation scenarios allowing prehospital redirection to E-CPR centers were created. Stringent eligibility criteria for E-CPR and redirection for E-CPR (e.g. age <60years old, initial shockable rhythm) were used in the first scenario, intermediate eligibility criteria (e.g. age <65years old, at least one shock given) in the second scenario and inclusive eligibility criteria (e.g. age <70years old, initial rhythm ≠ asystole) in the third scenario. All three scenarios were contrasted with equivalent scenarios in which patients were transported to the closest hospital. Proportions were compared using McNemar's test. RESULTS: The proportion of E-CPR eligible patients transported to E-CPR capable centers increased in each scenario (stringent criteria: 48 [24.5%] vs 155 patients [79.1%], p<0.001; intermediate criteria: 81 [29.6%] vs 262 patients [95.6%], p<0.001; inclusive criteria: 238 [23.9%] vs 981 patients [98.5%], p<0.001). CONCLUSIONS: A prehospital redirection system could significantly increase the number of patients with refractory OHCA transported to E-CPR capable centers, thus increasing their access to this potentially life-saving procedure, provided allocated resources are planned accordingly.

Prehospital Advanced Cardiac Life Support for Out-of-hospital Cardiac Arrest: A Cohort Study.

OBJECTIVES: Out-of-hospital advanced cardiac life support (ACLS) has not consistently shown a positive impact on survival. Extracorporeal cardiopulmonary resuscitation (E-CPR) could render prolonged on-site resuscitation (ACLS or basic cardiac life support [BCLS]) undesirable in selected cases. The objectives of this study were to evaluate, in patients suffering from out-of-hospital cardiac arrest (OHCA) and in a subgroup of potential E-CPR candidates, the association between the addition of prehospital ACLS to BCLS and survival to hospital discharge, prehospital return of spontaneous circulation (ROSC), and delay from call to hospital arrival. METHODS: This cohort study targets adult patients treated for OHCA between April 2010 and December 2015 in the city of Montreal, Canada. We defined potential E-CPR candidates using clinical criteria previously described in the literature (65 years of age or younger, initial shockable rhythm, absence of ROSC after 15 minutes of prehospital resuscitation, and emergency medical services-witnessed collapse or witnessed collapse with bystander cardiopulmonary resuscitation). Associations were evaluated using multivariate regression models. RESULTS: A total of 7,134 patients with OHCA were included, 761 (10.7%) of whom survived to discharge. No independent association between survival to hospital discharge and the addition of prehospital ACLS to BCLS was found in either the entire cohort (adjusted odds ratio [AOR] = 1.05 [95% confidence interval {CI} = 0.84-1.32], p = 0.68) or among the 246 potential E-CPR candidates (AOR = 0.82 [95% CI = 0.36-1.84], p = 0.63). The addition of prehospital ACLS to BCLS was associated with a significant increase in the rate of prehospital ROSC in all patients experiencing OHCA (AOR = 3.92 [95% CI = 3.38-4.55], p < 0.001) and in potential E-CPR candidates (AOR = 3.48 [95% CI = 1. 76-6.88], p < 0.001) compared to isolated prehospital BCLS. Delay from call to hospital arrival was longer in the ACLS group than in the BCLS group (difference = 16 minutes [95% CI = 15-16 minutes], p < 0.001). CONCLUSIONS: In a tiered-response urban emergency medical service setting, prehospital ACLS is not associated with an improvement in survival to hospital discharge in patients suffering from OHCA and in potential E-CPR candidates, but with an improvement in prehospital ROSC and with longer delay to hospital arrival.