Dynamics of Capillary Lactate Levels in Patients with Out-of-Hospital Cardiac Arrest.

Background and Objectives: An effective strategy for cardiopulmonary resuscitation should be based on tissue perfusion. Our primary aim was to determine the association between capillary lactate values and initial rhythm as well as the probability of the return of spontaneous circulation in out-of-hospital cardiac arrest patients. Materials and Methods: This prospective observational cohort study included all patients with non-traumatic out-of-hospital cardiac arrest, older than 18 years, resuscitated by a prehospital emergency medical team between April 2020 and June 2021. Capillary lactate samples were collected at the time of arrival and every 10 min after the first measurement until the time of the return of spontaneous circulation (ROSC) or, if ROSC was not achieved, at the time of declaring death on the scene. Results: In total, 83 patients were enrolled in the study. ROSC was achieved in 28 patients (33.7%), 21 were admitted to hospital (26.3%), and 6 (7.23%) of them were discharged from hospital. At discharge, all patients had Cerebral Performance Category Scale 1 or 2. Initial capillary lactate values were significantly higher in patients with a non-shockable rhythm compared to the group with a shockable rhythm (9.19 ± 4.6 versus 6.43 ± 3.81; p = 0.037). A significant difference also persisted in a second value taken 10 min after the initial value (10.03 ± 5,19 versus 5.18 ± 3.47; p = 0.019). Capillary lactate values were higher in the ROSC group and non-ROSC group at the time of restored circulation (11.10 ± 6.59 and 6.77 ± 4.23, respectively; p = 0.047). Conclusions: Capillary lactate values are significantly higher in patients with a non-shockable first rhythm in out-of-hospital cardiac arrest (OHCA). There is also a significantly different rise in capillary lactate levels in patients with ROSC.

Prehospital Predictors of Survival in Patients with Out-of-Hospital Cardiac Arrest.

Background and Objectives: Despite advances in the treatment of heart diseases, the outcome of patients experiencing sudden cardiac arrest remains poor. The aim of our study was to determine the prehospital variables as predictors of survival outcomes in out-of-hospital cardiac arrest (OHCA) victims. Materials and Methods: This was a retrospective observational cohort study of OHCA cases. EMS protocols created in accordance with the Utstein style reporting for OHCA, first responder intervention reports, medical dispatch center dispatch protocols and hospital medical reports were all reviewed. Multivariate logistic regression was performed with the following variables: age, gender, witnessed status, location, bystander CPR, first rhythm, and etiology. Results: A total of 381 interventions with resuscitation attempts were analyzed. In more than half (55%) of them, bystander CPR was performed. Thirty percent of all patients achieved return of spontaneous circulation (ROSC), 22% of those achieved 30-day survival (7% of all OHCA victims), and 73% of those survived with Cerebral Performance Score 1 or 2. The logistic regression model of adjustment confirms that shockable initial rhythm was a predictor of ROSC [OR: 4.5 (95% CI: 2.5-8.1)] and 30-day survival [OR: 9.3 (95% CI: 2.9-29.2)]. Age was also associated (≤67 years) [OR: 3.9 (95% CI: 1.3-11.9)] with better survival. Conclusions: Elderly patients have a lower survival rate. The occurrence of bystander CPR in cardiac arrest remains alarmingly low. Shockable initial rhythm is associated with a better survival rate and neurological outcome compared with non-shockable rhythm.

Retention of Knowledge and Skills After a Basic Life Support Course for Schoolchildren: A Prospective Study.

Courses on basic life support (BLS) and automated external defibrillator (AED) in schools lead to increase in knowledge but its retention is less well explored. We aimed to explore the long-term retention of knowledge and practical skills among schoolchildren after a BLS and AED course to be able to tailor future courses accordingly. Study was conducted in 3 parts and included 823 seventh and ninth graders from different elementary schools in Maribor, Slovenia. In Study 1 (n=611) we assessed students' baseline knowledge and immediate knowledge gain after our BLS and AED course with a validated questionnaire; in Study 2 (n=116) we assessed retention of gained knowledge and skills after 5 months with a modified Cardiff test and Little Anne QCPR manikin; in Study 3 (n=96) we assessed retention of knowledge 2 years after the course. Mean differences in knowledge before and after the course in Study 1 and between studies were analyzed using paired t-tests and independent t-tests. Differences between individual question scores at different time points were compared using Mann - Whitney U test. A two-sided P<0,05 was considered significant. Practical skills retention was presented with descriptive statistics. Knowledge gain was significant immediately after the course with 83% correct answers compared to 60% at baseline. Scores dropped significantly after 5 months (73%) and after 2 years (75%), but remained significantly better than at baseline (P<0.001). Practical skills perfomance score as per Cardiff test after 5 months was 63%. Overall BLS performance score as per QCPR app was 59%, with an overall cardio score of 77% (average compression rate: 124/min and depth: 52 mm) and ventilation score of 44%. This study showed that long term retention of theoretical knowledge was satisfying whereas poor practical skills performance after 5 months calls for a more intense practical training on repeat courses.

Validated Assessment of Schoolchildren's Attitude Towards Basic Life Support and Automated External Defibrillator Use.

As knowledge and attitude towards performing basic life support and using an automated external defibrillator (BLS and AED) contribute equally to improving survival after out-of-hospital cardiac arrest, we aimed to develop a measuring instrument for a validated assessment of schoolchildrens' attitude towards BLS and AED. The objective was to identify, measure, and address pertinent attitude dimensions that influence the intention to actually perform BLS and AED. We conducted a BLS and AED course for seventh and ninth grade students. Students fulfilled pre- and post-course questionnaires on attitude and intention to perform BLS and AED. The measuring instrument was developed with the use of exploratory factor analysis with application of principal component analysis and confirmatory factor analysis with application of structural equation modeling. Measurement invariance across different groups (gender, grades, previous courses) was tested with Wilcoxon signed ranks test and Mann-Whitney U test. Differences in attitude pre- and post-course were evaluated by application of Mann-Whitney U test. The final attitude model consisted of 3 behavioral constructs (self-confidence, positive motivation, and amotivation). Self-confidence was the major construct directly affecting the intention to act. Positive motivation had a negligible direct effect on intention but correlated strongly with self-confidence. The effect of attitude on the intention to help is therefore less complicated than was expected, which relieves the non-professional educators of having to know the specifics of the different behavioral constructs.

Development, validation and assessment of the test on knowledge about basic life support and use of automated external defibrillator among schoolchildren.

BACKGROUND: Educating lay public can significantly strengthen the Chain of Survival after out of hospital cardiac arrest. Schoolchildren are an accessible population for learning basic life support (BLS) and use of an automated external defibrillator (AED) and can be regarded as multipliers of knowledge that can reach the whole population. This study aimed to develop and validate a test for examining levels of knowledge about BLS and AED among schoolchildren that can be used to uniformly present reliable data. METHODS: A knowledge test about BLS and AED consisting of 10 multiple-choice questions was developed and implemented before and after a 2-h BLS and AED course consisting of an interactive lecture and a practical workshop for 783 students in seventh and ninth grades of elementary schools in Maribor, Slovenia. Each question was analyzed and presented with descriptive statistics and educometric parameters (difficulty and discriminating indices). All variables were checked for normality with the Kolmogorov-Smirnov test and analyzed using non-parametric tests. Statistical significance of the differences in knowledge before and after intervention were calculated with chi-square statistics and effect sizes r are reported. Differences between genders, grades and previous attendance to BLS courses were compared using Mann - Whitney U test. The effect size was calculated from the Z score and reported as r value. RESULTS: After educometric analysis, questions were adjusted to meet the requirements of satisfactory functioning difficulty and discriminating indices (values between 0,40 and 0,60, and above 0,20, respectively). Only one question had to be eliminated due to inadequate difficulty and discriminating index (0,99 and 0,02, respectively). Measurement invariance across gender (p < 0,001), school grade (p < 0,001), and attendance to previous courses (p = 0,303) was assured. CONCLUSIONS: A test for accurate and reliable measurement of knowledge of BLS and AED among schoolchildren was developed and validated. According to the findings it can now reliably be used to assess baseline knowledge and potential improvement in knowledge after a course on BLS and AED. Standardized data gathered with a validated tool can now be presented at legislative levels to promote BLS and AED courses implementation in school curricula.

Cerebral tissue oximetry levels during prehospital management of cardiac arrest - A prospective observational study.

INTRODUCTION: Near-infrared spectroscopy (NIRS) enables continuous monitoring of regional oximetry (rSO2). The aim of this study was to describe dynamics of regional cerebral oximetry levels during out of hospital cardiac arrest (OHCA) resuscitation, specifically around the time of restoration of spontaneous circulation (ROSC). METHODS: This prospective observational study was performed in the prehospital setting during cardio-pulmonary resuscitation (CPR) of OHCA patients. In the three-year study period, two-hundred eighty OHCA's were responded to; rSO2 was continuously measured throughout CPR and after attaining ROSC. RESULTS: Final data analysis included 53 patients. Continuous rSO2dynamics were described and data was compared amongst ROSC (22 cases) and no-ROSC (31 cases) groups. Initial rSO2levels were below 15% (not detectable) in both groups. With ongoing CPR, rSO2levels were higher in the ROSC group (median 22% vs. 14% in no-ROSC group, p = 0.030). Until ROSC, rSO2levels were higher throughout CPR before ROSC (mean maximal value 47% at ROSC vs. 31% no-ROSC, p < 0.01). Furthermore, we found a pattern of significant, rapid and sustained rise in rSO2levels minutes prior to ROSC and normalization thereafter. CONCLUSIONS: Initial rSO2levels during OHCA are generally undetectable by the time EMS teams initiate CPR. With CPR, rSO2levels rise and are higher during CPR in patients who later achieve ROSC. Patients who achieve ROSC exhibit significant, rapid, and sustained rise in rSO2minutes prior to attaining ROSC, and normalization of rSO2 levels thereafter. Persistently low levels of rSO2 during CPR likely portend poor neurologic outcomes.

Predictors of mortality in patients with isolated severe traumatic brain injury.

BACKGROUND: Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Many prognostic models predicting mortality in patients with TBI were developed, which also include patients with mild or moderate TBI and patients who suffered major extracranial injuries. METHODS: From a prospective database, we conducted a retrospective medical chart review covering the period between January 2000 and December 2012 of patients with isolated severe TBI (Abbreviated Injury Score for head, AISH ≥ 3) without extracranial injuries, who were intubated in the field using the rapid sequence intubation method and were of age 16 or more. Prehospital vital signs, Injury Severity Score (ISS) and laboratory tests were compared in two study groups: survivors (n = 25) and non-survivors (n = 27). Selected variables identified during univariate analysis (p < 0.1) were then subjected to multivariate analysis logistic regression model. RESULTS: Univariate analysis showed that in-hospital mortality was statistically significantly associated with male sex (p = 0.040), ISS (p = 0.005) and mydriasis (p = 0.012). For predicting mortality, area under the curve (AUC) was calculated: for ISS 0.76 (95 % confidence interval, CI; 0.63-0.90; p < 0.001) and for initial Glasgow Coma Scale (GCS) 0.64 (95 % CI, 0.49-0.80, p = 0.079). In the multivariate analysis, ISS (odds ratio, OR; 1.19, 95 % CI, 1.06-1.35; p = 0.004) and mydriasis (OR, 5.73; 95 % CI, 1.06-30.88; p = 0.042) were identified as independent risk factors for in-hospital mortality. The AUC for the regression model was 0.83 (95 % CI, 0.71-0.94; p < 0.001). CONCLUSIONS: In prehospital intubated patients with isolated severe TBI only ISS and mydriasis were found to be independent predictors of in-hospital mortality.

Bedside lung ultrasound for monitoring the effectiveness of prehospital treatment with continuous positive airway pressure in acute decompensated heart failure.

OBJECTIVE: The aim of this pilot study was to determine the usefulness of prehospital lung ultrasound in monitoring the effectiveness of treatment with continuous positive airway pressure (CPAP) versus standard therapy in patients with acute decompensated heart failure (ADHF). MATERIALS AND METHODS: Twenty patients with ADHF were enrolled in this prospective, observational study. They were allocated randomly to a CPAP group (CPAP and standard therapy) or a control group (standard therapy only). Lung ultrasound was performed in each group and B-lines were counted and compared before and after treatment. RESULTS: There were statistically significant differences before and after treatment in partial pressure of end-tidal carbon dioxide (29.9±5.2 vs. 32.9±5.5 mmHg, P=0.011), respiratory rate (33.3±9.3 vs. 26.6±7.5 min, P=0.013), arterial oxygen saturation (82.0±9.4 vs. 97.3±1.3%, P<0.001), and total number of B-lines (46.9±14.8 vs. 29.0±16.2, P<0.001) in the CPAP group. There was a significant difference in required O2 added to either therapy to obtain adequate saturation - 40% in the CPAP group versus 100% in the control group (P<0.001). Percentage of positive ultrasound lung scans reduced in the middle axillary line and reached a statistically significant difference in the CPAP group [67 vs. 25% in medium right, P=0.017; 91 vs. 55% in basal right (fourth intercostal space), P=0.038; 83 vs. 33% in medium left, P=0.007; and 92 vs. 58% in basal left (fourth intercostal space), P=0.039]. CONCLUSION: Bedside lung ultrasound is a reliable monitoring tool in a prehospital emergency setting and findings from lung ultrasound scans correspond with improved hemodynamic parameters in patients with ADHF treated with CPAP compared with standard therapy only.

Estrogen fails to facilitate resuscitation from ventricular fibrillation in male rats.

Administration of 17ß-estradiol has been shown to exert myocardial protective effects in hemorrhagic shock. We hypothesized that similar protective effects could help improve resuscitation from cardiac arrest. Three series of 18, 40, and 12 rats each, underwent ventricular fibrillation for 8 minutes followed by 8 minutes of chest compression and delivery of electrical shocks. In series-1, rats were randomized 1:1 to receive a bolus dose of 17ß-estradiol (1 mg/kg) or 0.9% NaCl before chest compression; in series-2, rats were randomized 1:1:1:1 to receive a continuous infusion of 0.9% NaCl or a 17ß-estradiol solution designed to attain a plasma level of 10(0), 10(2), or 10(4) nM during chest compression; and in series-3, rats were randomized 1:1 to receive a continuous infusion of 17ß-estradiol to attain a plasma level of 10(2) nM or 0.9% NaCl during chest compression, providing inotropic support during the post-resuscitation interval using dobutamine infusion. 17ß-estradiol failed to facilitate resuscitation in each of the 3 series. In series-1 and series-2, resuscitability and short-term survival was reduced in 17ß-estradiol groups attaining statistical significance in series-2 when the three 17ß-estradiol groups were combined (p = 0.035). In series-3, all rats were resuscitated and survived for 180 minutes aided by dobutamine which partially reversed post-resuscitation myocardial dysfunction but without additional benefits on myocardial function in the 17ß-estradiol group. The present study failed to support a beneficial effect of 17ß-estradiol for resuscitation from cardiac arrest and raised the possibility of detrimental cardiac effects compromising initial resuscitability and subsequent survival in a male rat model of ventricular fibrillation and closed chest resuscitation.

Effects of intraosseous erythropoietin during hemorrhagic shock in swine.

OBJECTIVE: To determine whether erythropoietin given during hemorrhagic shock (HS) ameliorates organ injury while improving resuscitation and survival. METHODS: Three series of 24 pigs each were studied. In an initial series, 50% of the blood volume (BV) was removed in 30 minutes and normal saline (threefold the blood removed) started at minute 90 infusing each third in 30, 60, and 150 minutes with shed blood reinfused at minute 330 (HS-50BV). In a second series, the same HS-50BV protocol was used but removing an additional 15% of BV from minute 30 to 60 (HS-65BV). In a final series, blood was removed as in HS-65BV and intraosseous vasopressin given from minute 30 (0.04 U/kg min(-1)) until start of shed blood reinfusion at minute 150 (HS-65BV+VP). Normal saline was reduced to half the blood removed and given from minute 90 to 120 in half of the animals. In each series, animals were randomized 1:1 to receive erythropoietin (1,200 U/kg) or control solution intraosseously after removing 10% of the BV. RESULTS: In HS-50BV, O2 consumption remained near baseline yielding minimal lactate increases, 88% resuscitability, and 60% survival at 72 hours. In HS-65BV, O2 consumption was reduced and lactate increased yielding 25% resuscitability. In HS-65BV+VP, vasopressin promoted hemodynamic stability yielding 92% resuscitability and 83% survival at 72 hours. Erythropoietin did not affect resuscitability or subsequent survival in any of the series but increased interleukin-10, attenuated lactate increases, and ameliorated organ injury based on lesser troponin I, AST, and ALT increases and lesser neurological deficits in the HS-65BV+VP series. CONCLUSIONS: Erythropoietin given during HS in swine failed to alter resuscitability and 72 hour survival regardless of HS severity and concomitant treatment with fluids and vasopressin but attenuated acute organ injury. The studies also showed the efficacy of vasopressin and restrictive fluid resuscitation for hemodynamic stabilization and survival.

High-dose erythropoietin during cardiac resuscitation lessens postresuscitation myocardial stunning in swine.

We investigated the metabolic and functional myocardial effects of erythropoietin (EPO) administered during resuscitation from cardiac arrest using an open-chest pig model of ventricular fibrillation and resuscitation by extracorporeal circulation, after having reported in rats a reversal of postresuscitation myocardial dysfunction associated with activation of mitochondrial protective pathways. Ventricular fibrillation was induced in 16 male domestic pigs and left untreated for 8 minutes, after which extracorporeal circulation was started and maintained for 10 additional minutes, adjusting the extracorporeal flow to provide a coronary perfusion pressure of 10 mmHg. Defibrillation was accomplished and the extracorporeal flow was adjusted to secure a mean aortic pressure of 40 mmHg or greater during spontaneous circulation for up to 120 minutes. Pigs were randomized 1:1 to receive EPO (1200 U/kg) or 0.9% NaCl before starting extracorporeal circulation. Severe postresuscitation myocardial dysfunction developed in both groups. However, recovery of myocardial function-comparing baseline with 120 minutes postresuscitation-was better in pigs treated with EPO than NaCl, as shown for left ventricular ejection fraction (from 45 ± 8% to 36 ± 9% in EPO, not significant; and from 46 ± 8% to 26 ± 8% in NaCl, P < 0.001) and for peak systolic pressure/end-systolic volume (from 2.7 ± 0.8 mmHg/mL to 2.4 ± 0.7 mmHg/mL in EPO, not significant; and from 3.0 ± 1.1 mmHg/mL to 1.8 ± 0.6 mmHg/mL, P < 0.001 in NaCl). The EPO effect was associated with significantly higher myocardial O2 consumption (12 ± 6 mL/min/unit of tissue vs 6 ± 2 mL/min/unit of tissue, P < 0.017) without effects on myocardial lactate consumption. Thus, EPO administered during resuscitation from ventricular fibrillation lessened postresuscitation myocardial stunning-an effect that could be useful clinically to help promote postresuscitation hemodynamic stability.

LUCAS 2™ device, compression depth, and the 2010 cardiopulmonary resuscitation guidelines.

The 2010 guidelines for cardiopulmonary resuscitation recommends that the chest be compressed at least 5 cm, with evidence that depths exceeding 5 cm may further aid resuscitation. The current piston-based mechanical device LUCAS 2™ is programmed to deliver a compression depth of 5 cm. We report 2 cases in which the LUCAS 2™ device failed to generate physiological surrogates of blood flow (ie, end-tidal carbon dioxide tension and aortic diastolic blood pressure) at levels indicative of effective chest compressions. A switch to manual compressions allowing greater compression depth yielded higher end-tidal carbon dioxide tension and arterial blood pressure. These cases depict limitations of the LUCAS 2™ device and the importance of guiding chest compression by physiological parameters. Consideration should be given to modifications to the LUCAS 2™, allowing rescuers to increase depth when required to optimize the hemodynamic efficacy of chest compression.