1. Optimization of induction of mild therapeutic hypothermia with cold saline infusion : a laboratory experimentJure Fluher, Andrej Markota, Andraž Stožer, Andreja Sinkovič, 2015, original scientific article Abstract: Cold fluid infusions can be used to induce mild therapeutic hypothermia after cardiac arrest. Fluid temperature higher than 4°C can increase the volume of fluid needed, prolong the induction phase of hypothermia and thus contribute to complications. We performed a laboratory experiment with two objectives. The first objective was to analyze the effect of wrapping fluid bags in ice packs on the increase of fluid temperature with time in bags exposed to ambient conditions. The second objective was to quantify the effect of insulating venous tubing and adjusting flow rate on fluid temperature increase from bag to the level of an intravenous cannula during a simulated infusion. The temperature of fluid in bags wrapped in ice packs was significantly lower compared to controls at all time points during the 120 minutes observation. The temperature increase from the bag to the level of intravenous cannula was significantly lower for insulated tubing at all infusion rates (median temperature differences between bag and intravenous cannula were: 8.9, 4.8, 4.0, and 3.1°C, for non-insulated and 5.9, 3.05, 1.1, and 0.3°C, for insulated tubing, at infusion rates 10, 30, 60, and 100 mL/minute, respectively). The results from this study could potentially be used to decrease the volume of fluid infused when inducing mild hypothermia with an infusion of cold fluids.
Keywords: cardiac arrest, intravenous infusion, therapeutic hypothermia
Published in DKUM: 03.08.2017; Views: 926; Downloads: 138
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2. The effect of carbon dioxide on near-death experiences in out-of-hospital cardiac arrest survivors: a prospective observational studyZalika Klemenc-Ketiš, Janko Kersnik, Štefek Grmec, 2010, original scientific article Abstract: Introduction: Near-death experiences (NDEs) are reported by 11-23% of cardiac arrest survivors. Several theories concerning the mechanisms of NDEs exist - including physical, psychological, and transcendental reasons - but so far none of these has satisfactorily explained this phenomenon. In this study, we investigated the effect of partial pressures of O2 and CO2, and serum levels of Na and K on the occurrence of NDEs in out-of-hospital cardiac arrest survivors.
Methods: A prospective observational study was conducted in the three largest hospitals in Slovenia. Fifty-two consecutive patients (median age 53.1 years, 42 males) after out-of-hospital cardiac arrest were included. The presence of NDEs was assessed with a self-administered Greyson's NDE scale. The initial partial pressure of end-tidal CO2, the arterial blood partial pressures of O2 and CO2 and the levels of Na and K in venous blood were analysed and studied. Univariate analyses and multiple regression models were used.
Results: NDEs were reported by 11 (21.2%) of the patients. Patients with higher initial partial pressures of end-tidal CO2 had significantly more NDEs (P < 0.01). Patients with higher arterial blood partial pressures of CO2 had significantly more NDEs (P = 0.041). Scores on a NDE scale were positively correlated with partial pressures of CO2 (P = 0.017) and with serum levels of potassium (P = 0.026). The logistic regression model for the presence of NDEs (P = 0.002) explained 46% of the variance and revealed higher partial pressures of CO2 to be an independent predictor of NDEs. The linear regression model for a higher score on the NDE scale (P = 0.001) explained 34% of the variance and revealed higher partial pressures of CO2, higher serum levels of K, and previous NDEs as independent predictors of the NDE score.
Conclusions: Higher concentrations of CO2 proved significant, and higher serum levels of K might be important in the provoking of NDEs. Since these associations have not been reported before, our study adds novel information to the field of NDEs phenomena.
Keywords: near-death experience, cardiac arrest, survivors
Published in DKUM: 29.06.2017; Views: 1015; Downloads: 355
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3. The dynamic pattern of end-tidal carbon dioxide during cardiopulmonary resuscitation - difference between asphyxial cardiac arrest and ventricular fibrillation/pulseless ventricular tachycardia cardiac arrestKatja Lah, Miljenko Križmarić, Štefek Grmec, 2011, original scientific article Abstract: Introduction: Partial pressure of end-tidal carbon dioxide (PetCO2) during cardiopulmonary resuscitation (CPR) correlates with cardiac output and consequently has a prognostic value in CPR. In our previous study we confirmed that initial PetCO2 value was significantly higher in asphyxial arrest than in ventricular fibrillation/pulseless ventricular tachycardia (VF/VT) cardiac arrest. In this study we sought to evaluate the pattern of PetCO2 changes in cardiac arrest caused by VF/VT and asphyxial cardiac arrest in patients who were resuscitated according to new 2005 Guidelines.
Methods: The study included two cohorts of patients: cardiac arrest due to asphyxia with initial rhythm asystole or pulseless electrical activity (PEA), and cardiac arrest due to arrhythmia with initial rhythm VF or pulseless VT. PetCO2 was measured for both groups immediately after intubation and repeatedly every minute, both for patients with or without return of spontaneous circulation (ROSC). We compared the dynamic pattern of PetCO2 between groups.
Results: Between June 2006 and June 2009 resuscitation was attempted in 325 patients and in this study we included 51 patients with asphyxial cardiac arrest and 63 patients with VF/VT cardiac arrest. The initial values of PetCO2 were significantly higher in the group with asphyxial cardiac arrest (6.74 +/- 4.22 kPa versus 4.51 +/- 2.47 kPa; P = 0.004). In the group with asphyxial cardiac arrest, the initial values of PetCO2 did not show a significant difference when we compared patients with and without ROSC (6.96 +/- 3.63 kPa versus 5.77 +/- 4.64 kPa; P = 0.313). We confirmed significantly higher initial PetCO2 values for those with ROSC in the group with primary cardiac arrest (4.62 +/- 2.46 kPa versus 3.29 +/- 1.76 kPa; P = 0.041). A significant difference in PetCO2 values for those with and without ROSC was achieved after five minutes of CPR in both groups. In all patients with ROSC the initial PetCO2 was again higher than 1.33 kPa.
Conclusions: The dynamic pattern of PetCO2 values during out-of-hospital CPR showed higher values of PetCO2 in the first two minutes of CPR in asphyxia, and a prognostic value of initial PetCO2 only in primary VF/VT cardiac arrest. A prognostic value of PetCO2 for ROSC was achieved after the fifth minute of CPR in both groups and remained present until final values. This difference seems to be a useful criterion in prehospital diagnostic procedures and attendance of cardiac arrest.
Keywords: end-tidal carbon dioxide, ETCO2, cardiopulmonary resuscitation, CPR, asphyxial cardiac arrest, ventricular fibrillation, pulseless ventricular tachycardia, cardiac arrest
Published in DKUM: 29.06.2017; Views: 1012; Downloads: 397
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4. Partial pressure of end-tidal carbon dioxide successful predicts cardiopulmonary resuscitation in the field - a prospective observational studyMiran Kolar, Miljenko Križmarić, Petra Klemen, Štefek Grmec, 2008, original scientific article Abstract: Introduction: The prognosis among patients who suffer out-of-hospital cardiac arrest is poor. Higher survival rates have been observed only in patients with ventricular fibrillation who were fortunate enough to have basic and advanced life support initiated early after cardiac arrest. The ability to predict outcomes of cardiac arrest would be useful for resuscitation. Changes in expired end-tidal carbon dioxide levels during cardiopulmonary resuscitation may be a useful non-invasive predictor of successful resuscitation and survival from cardiac arrest, and help in the termination of cardiopulmonary resuscitation in the field.
Methods: This is a prospective observational study of 737 cases of victims who suffered sudden out-of-hospital cardiac arrest. The patients were intubated and the measurements of end-tidal carbon dioxide were performed. Data according to the Utstein criteria, demographic information, medical data and partial pressure of end-tidal carbon dioxide (petCO2) values were collected for each patient in cardiac arrest, by the emergency physician. We presumed that an end-tidal carbon dioxide level of 1.9 kPa (14.3 mmHg) or more after 20 minutes of standard advanced cardiac life support would predict restoration of spontaneous circulation (ROSC).
Results: Partial pressure of end-tidal carbon dioxide after 20 minutes of advanced life support averaged 0.92+/- 0.29 kPa (6.9mmHg +/- 2.2 mmHg) in patients who did not have ROSC and 4.36 +/-1.11 kPa (32.8 mmHg +/- 9.1 mmHg) in those who did (p<0,001). End-tidal carbon dioxide values of 1.9 kPa (14.3 mmHg) or less discriminated between the 402 patients with ROSC and 335 patients without ROSC. When a 20-minute end-tidal carbon dioxide value of 1.9 kPa (14.3 mmHg) or less was used as a screening test to predict ROSC, the sensitivity, specificity, positive predictive value, and negative predictive value were all 100 percent.
Conclusions: Measurements of end-tidal carbon dioxide levels of more than 1.9 kPa (14.3 mmHg) after 20 minutes should be used to accurately predict ROSC. End-tidal carbon dioxide levels should be monitored during cardiopulmonary resuscitation and considered a useful prognostic value for determining the outcome of resuscitative efforts and termination of cardio-pulmonary resuscitation in the field.
Keywords: out-of-hospital cardiac arrest, cardiopulmonary resuscitation, CPR, partial pressure of end-tidal carbon dioxide, PetCO2
Published in DKUM: 29.06.2017; Views: 1509; Downloads: 138
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5. Predicting defibrillation success by "genetic" programming in patients with out-of-hospital cardiac arrestMatej Podbregar, Miha Kovačič, Aleksandra Podbregar-Marš, Miran Brezočnik, 2003, original scientific article Abstract: In some patients with ventricular fibrillation (VF) there may be a better chance of successful defibrillation after a period of chest compression and ventilation before the defibrillation attempt. It is therefore important to know whether a defibrillation attempt will be successful. The predictive powerof a model developed by "genetic" programming (GP) to predict defibrillation success was studied. Methods and Results: 203 defibrillations were administered in 47 patients with out-of-hospital cardiac arrest due to a cardiac cause. Maximal amplitude, a total energy of power spectral density, and the Hurst exponent of the VF electrocardiogram (ECG) signal were included in the model developed by GP. Positive and negative likelihood ratios of the model for testing data were 35.5 and 0.00, respectively. Using a model developed by GP on the complete database, 120 of the 124 unsuccessful defibrillations would have been avoided, whereas all of the 79 successful defibrillations would have been administered. Conclusion: The VF ECG contains information predictive of defibrillation success. The model developed by GP, including data from the time-domain, frequency-domain and nonlinear dynamics, could reduce the incidence of unsuccessful defibrillations.
Keywords: optimisation methods, evolutionary optimisation methods, genetic algorithms, genetic programming, defibrillation, cardiac arrest prediction
Published in DKUM: 01.06.2012; Views: 1667; Downloads: 92
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6. Prediction of maintenance of sinus rhythm after electrical cardioversion of atrial fibrillation by non-deterministic modellingPetra Žohar, Miha Kovačič, Miran Brezočnik, Matej Podbregar, 2005, original scientific article Abstract: Atrial fibrillation (AF) is the most common rhythm disorder. Because of the high recurrence rate of AF after cardioversion and because of potential side effects of electrical cardioversion, it is clinically important to predict persistence of sinus rhythm after electrical cardioversion before it is attempted. The aim of our study was the development of a mathematical model by"genetic" programming (GP), a non-deterministic modelling technique, which would predict maintenance of sinus rhythm after electrical cardioversion of persistent AF. PATIENTS AND METHODS: Ninety-seven patients with persistent AF lasting more than 48 h, undergoing the first attempt at transthoracic cardioversion were included in this prospective study. Persistence of AF before the cardioversion attempt, amiodarone treatment, left atrial dimension,mean, standard deviation and approximate entropy of ECG R-R intervals were collected. The data of 53 patients were randomly selected from the database and used for GP modelling; the other 44 data sets were used for model testing. RESULTS: In 23 patients sinus rhythm persisted at 3 months. In the other 21 patients sinus rhythm was not achieved or its duration was less than 3 months. The model developed by GP failed to predict maintenance ofsinus rhythm at 3 months in one patient and in six patients falsely predicted maintenance of sinus rhythm. Positive and negative likelihood ratiosof the model for testing data were 4.32 and 0.05, respectively. Using this model 15 of 21 (71.4%) cardioversions not resulting in sinus rhythm at 3 months would have been avoided, whereas 22 of 23 (95.6%) cardioversions resulting in sinus rhythm at 3 months would have been administered. CONCLUSION: This model developed by GP, including clinical data, ECG data from the time-domain and nonlinear dynamics can predict maintenance of sinus rhythm. Further research is needed to explore its utility in the present or anexpanded form.
Keywords: optimisation methods, evolutionary optimisation methods, genetic algorithms, genetic programming, defibrillation, cardiac arrest prediction, atrial fibrillation, electrical cardioversion, prediction
Published in DKUM: 01.06.2012; Views: 1957; Downloads: 78
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