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.

Association Between the Quantity of Subcutaneous Fat and the Inter-Device Agreement of 2 Tissue Oximeters.

OBJECTIVE: This study aimed to evaluate the association between the quantity of subcutaneous fat (assessed by skinfold thickness) and the inter-device agreement of 2 tissue oximeters. DESIGN: This is a prospective cohort study. SETTING: This study was conducted in a tertiary care academic urban hospital. PARTICIPANTS: Healthy volunteers were recruited. INTERVENTIONS: All patients recruited had their tissue saturations and skinfold thickness measured at 4 different sites (shoulder, forearm, knee, and calf) on both sides of the body using 2 tissue oximeters, the INVOS 5100C and the EQUANOX 7600. MEASUREMENTS AND MAIN RESULTS: Higher skinfold measures were associated with an increase in the difference between measures provided by both oximeters (slope = -0.59, Pearson correlation coefficient = -0.51, p < 0.001). This observed association persisted in a linear mixed model (-0.48 [95% confidence interval [CI] -0.61 to -0.36], p < 0.001). The sex of the volunteers also influenced the inter-oximeter agreement (women: -5.77 [95% CI -8.43 to -3.11], p < 0.001), as well as the forearm sites (left forearm: -7.16 [95% CI -9.85 to -4.47], p < 0.001; right forearm:-7.01 [95% CI -9.61 to -4.40], p < 0.001). CONCLUSION: The inter-device agreement of the 2 studied oximeters is correlated to the quantity of subcutaneous fat. Monitoring using tissue oximetry should be interpreted with great care when sensors are placed on sites with a significant quantity of subcutaneous fat. In addition to the monitoring of cerebral oximetry, following the variations of saturations at the same peripheral site seems to remain the most secure way to use that technology for the monitoring of critically ill patients.

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.

Reproducibility, interchangeability of measures, time to measure stabilization, and reference values of two tissue oximeters in healthy volunteers.

This study aimed to compare two tissue oximeters, the INVOS 5100c and the Equanox 7600, in terms of their reproducibility and the interchangeability of their measures. In a randomized order, three measurements were taken at six different sites on both sides of the body in 53 healthy volunteers. Intraclass correlation coefficients (ICC) and within-subject standard deviation (Sw) were calculated for each device. The ICCs were compared using Fisher r-to-z transformation and the Sw were compared using paired-sample t-tests. We found no difference between the reproducibility of the INVOS {ICC=0.92 [95% confidence interval (CI) 0.90 to 0.93]} and Equanox [ICC=0.90 (95% CI 0.88 to 0.93)] in terms of ICCs (p=0.06). However, the Equanox [Sw=1.96 (95% CI 1.91 to 2.02)] showed a better Sw than the INVOS [Sw=2.11 (95% CI 2.05 to 2.17)] (p=0.019). Also, when compared directly to stable condition, the readings produced by the two oximeters varied considerably [ICC 0.43 (95% CI 0.36 to 0.49)]. When taken individually, both tissue oximeters displayed good reproducibility, the Equanox being slightly better than the INVOS in terms of absolute reproducibility. However, when compared, the oximeters showed poor interdevices agreement. Reference values were also described.

Near-infrared Spectroscopy Monitoring During Cardiac Arrest: A Systematic Review and Meta-analysis.

BACKGROUND: Tissue oximetry using near-infrared spectroscopy (NIRS) is a noninvasive monitor of cerebral oxygenation. This new technology has been used during cardiac arrest (CA) because of its ability to give measures in low-blood-flow situations. The aim of this study was to assess the evidence regarding the association between the types of NIRS measurements (mean, initial, and highest values) and resuscitation outcomes (return of spontaneous circulation [ROSC], survival to discharge, and good neurologic outcome) in patients undergoing cardiopulmonary resuscitation. METHODS: This review was registered (Prospero CRD42015017380) and is reported as per the PRISMA guidelines. Medline, Embase, and CENTRAL were searched. All studies, except case reports and case series of fewer than five patients, reporting on adults that had NIRS monitoring during CA were eligible for inclusion. Two reviewers assessed the quality of the included articles and extracted the data. The outcome effect was standardized using standardized mean difference (SMD). RESULTS: Twenty nonrandomized observational studies (15 articles and five conference abstracts) were included in this review, for a total of 2,436 patients. We found a stronger association between ROSC and mean NIRS values (SMD = 1.33; 95% confidence interval [CI] = 0.92 to 1.74) than between ROSC and initial NIRS measurements (SMD = 0.51; 95% CI = 0.23 to 0.78). There was too much heterogeneity among the highest NIRS measurements group to perform meta-analysis. Only two of the 75 patients who experienced ROSC had a mean NIRS saturation under 30%. Patients who survived to discharge and who had good neurologic outcome displayed superior combined initial and mean NIRS values than their counterparts (SMD = 1.63; 95% CI = 1.34 to 1.92; and SMD = 2.12; 95% CI = 1.14 to 3.10). CONCLUSIONS: Patients with good resuscitation outcomes have significantly higher NIRS saturations during resuscitation than their counterparts. The types of NIRS measurements during resuscitation influenced the association between ROSC and NIRS saturation. Prolonged failure to obtain a NIRS saturation higher than 30% may be included in a multimodal approach to the decision of terminating resuscitation efforts (Class IIb, Level of Evidence C-Limited Data).

Lipid emulsions in the treatment of acute poisoning: a systematic review of human and animal studies.

OBJECTIVE: To assess the evidence regarding the efficacy and safety of intravenous fat emulsion (IFE) in the management of poisoned patients. METHODS: We performed a systematic review of the literature with no time or language restriction. The electronic databases were searched from their inception until June 1, 2009 (Medline, EMBASE, ISI web of science, Biological abstract, LILACS, ChemIndex, Toxnet, and Proquest). We also examined the references of identified articles and the gray literature. The target interventions eligible for inclusion were administration of any IFE before, during, or after poisoning in human or animals. All types of studies were reviewed. Eligibility for inclusion and study quality scores, based on criteria by Jadad and the STROBE statement, were evaluated by independent investigators. The primary outcome was mortality. Secondary outcomes included neurologic, hemodynamic, and electrocardiographic variables, as well as adverse effects. RESULTS: Of the 938 publications identified by the search strategies, 74 met the inclusion criteria. We identified 23 animal trials, 50 human, and 1 animal case reports. Overall, the quality of evidence was weak and significant heterogeneity prevented data pooling. Available data suggest some benefits of IFE in bupivacaine, verapamil, chlorpromazine, and some tricyclic antidepressants and beta-blockers toxicity. No trial assessed the safety of IFE in the treatment of acute poisoning. CONCLUSION: The evidence for the efficacy of IFE in reducing mortality and improving hemodynamic, electrocardiographic, and neurological parameters in the poisoned patients is solely based on animal studies and human case reports. The safety of IFE has not been established.

Short-term benefits and risks of intravenous iron: a systematic review and meta-analysis.

BACKGROUND: Intravenous (IV) iron may correct anemia more efficiently than oral iron, but it has been associated with allergic and hemodynamic reactions, and it may increase the risks of infectious complications. The objective of this systematic review and meta-analysis was to clarify these controversial issues. STUDY DESIGN AND METHODS: Studies evaluating the use of IV iron compared to enteral or no iron with outcomes within 2 months of treatment initiation were identified. Only randomized controlled trials were included. When a meta-analysis was possible, studies were combined with the Review Manager of the Cochrane Collaboration Group 2003. Statistics were calculated as standardized mean differences (SMDs), with a random-effect model. RESULTS: Thirteen studies met inclusion criteria. Meta-analysis revealed a significant increase in the reticulocyte count (SMD, 0.70; 95% confidence interval [CI], 0.10-1.29; p = 0.02) and in ferritin levels (SMD, 1.18; 95% CI, 0.69-1.68; p = 0.00001), but it also showed that in such a short period of time, IV iron does not correct hemoglobin (Hb)-hematocrit (Hct) better than enteral or no iron. In a sensitivity analysis, however, the increase in Hb-Hct became significant in the nondextran group (SMD, 0.27; 95% CI, 0.04-0.51; p = 0.02). No increase in transferrin saturation was observed. Meta-analysis of the allergic and hemodynamic reactions was not possible as most studies did not clearly describe these outcomes. CONCLUSION: Our results suggest that treatment with nondextran IV iron may benefit a wide variety of patients. Randomized controlled studies are definitively needed to further evaluate the usefulness and safety of IV iron.

Erythropoietic response to two epoetin alfa regimens in critically ill patients: a pilot study.

STUDY OBJECTIVE: To compare the erythropoietic responses and tolerability of two recombinant human erythropoietin (EPO) regimens. DESIGN: Prospective, open-label, multicenter study. SETTING: Three multidisciplinary intensive care units in Québec, Canada. PATIENTS: Sixty critically ill patients. INTERVENTION: The first 30 patients received EPO 40,000 U/week (group A); the next 30 received 40,000 U twice/week (group B). MEASUREMENTS AND MAIN RESULTS: Percent change from baseline in reticulocyte count and hemoglobin concentration were evaluated in both groups on study days 7 and 14. The numbers of adverse events were also compared between the two groups. No statistically significant differences were found in the results between the two groups. CONCLUSION: Although the study had limitations, it suggested that EPO 40,000 U twice/week did not increase or sustain stimulation of the erythropoietic response compared with EPO 40,000 U/week in critically ill patients.

Bench-to-bedside review: iron metabolism in critically ill patients.

Critically ill patients frequently develop anemia due to several factors. Iron-withholding mechanisms caused by inflammation contribute to this anemia. The iron metabolism imbalances described or reported in all intensive care studies are similar to the values observed in anemia of inflammation. The administration of iron could be useful in the optimization of recombinant human erythropoietin activity, but this could be at the expense of bacterial proliferation. Since there is a lack of evidence to support either oral or intravenous iron administration in intensive care patients, further studies are necessary to determine the efficacy and safety of iron supplementation in conjunction with recombinant human erythropoietin in critically ill patients. We review the mechanisms leading to iron sequestration in the presence of inflammation. The present article also reviews the literature describing the iron status in critically ill patients and explores the role of iron supplementation in this setting.

Recombinant human erythropoietin use in intensive care.

OBJECTIVE: To review the literature concerning the role of recombinant human erythropoietin (rHuEPO) in reducing the need for transfusion in critically ill patients. DATA SOURCES: Articles were obtained through searches of the MEDLINE database (from 1990 to June 2001) using the key words erythropoietin, epoetin alfa, anemia, reticulocytes, hemoglobin, critical care, intensive care, critical illness, and blood transfusion. Additional references were found in the bibliographies of the articles cited. The Cochrane library was also consulted. STUDY SELECTION AND DATA EXTRACTION: Controlled, prospective, and randomized studies on the use of rHuEPO in critically ill adults were selected. DATA SYNTHESIS: Anemia is a common complication in patients requiring intensive care. It is caused, in part, by abnormally low concentrations of endogenous erythropoietin and is mainly seen in patients with sepsis and multiple organ dysfunction syndrome, in whom inflammation mediator concentrations are often elevated. High doses of rHuEPO produce a rapid response in these patients, despite elevated cytokine concentrations. There have been 3 studies on rHuEPO administration in intensive care and 1 trial in acutely burned patients. Only 2 of these studies looked at the impact of rHuEPO administration on the need for transfusion. CONCLUSIONS: Few randomized, controlled trials explore the role of rHuEPO in critical care. Only 1 was a large, randomized clinical trial, but it presents many limitations. Future outcome and safety studies comparing rHuEPO with placebo must include clinical endpoints such as end-organ morbidity, mortality, transfusion criteria, and pharmacoeconomic analysis. rHuEPO appears to provide an erythropoietic response. Optimal dosage and the real impact of rHuEPO on the need for transfusion in intensive care remain to be determined. Currently, based on the evidence available from the literature, rHuEPO cannot be recommended to reduce the need for red blood cell transfusions in anemic, critically ill patients.