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Metzger A.K.,University of Minnesota | Herman M.,Rochester College | McKnite S.,Minnesota Medical Research Foundation | Tang W.,Weil Institute of Critical Care Medicine | Yannopoulos D.,University of Minnesota
Critical Care Medicine | Year: 2012

Objective: Generation of negative intrathoracic pressure during the decompression phase of cardiopulmonary resuscitation enhances the refilling of the heart. We tested the hypothesis that when compared with closed-chest manual compressions at 80 chest compressions per min, treatment with active compression-decompression cardiopulmonary resuscitation at 80 chest compressions/min combined with augmentation of negative intrathoracic pressure would lower intracranial pressure and increase cerebral perfusion, thereby improving neurologically intact survival rates following prolonged untreated cardiac arrest. Design: Prospective, randomized animal study. Setting: Animal laboratory facilities. Subjects: A total of 26 female farm pigs in two different protocols (n = 17 and n = 9). Interventions, Measurements, and Main Results: Seventeen pigs were subjected to 8.5 mins of untreated ventricular fibrillation and prospectively randomized to cardiopulmonary resuscitation at 80 chest compressions/min or active compression-decompression cardiopulmonary resuscitation at 80 chest compressions/min plus an impedance threshold device. Coronary perfusion pressures (29.5 ± 2.7 mm Hg vs. 22.4 ± 1.6 mm Hg, p = .03), carotid blood flow (44.0 ± 12.2 vs. 30.9 ± 10.4, p = .03), and 24-hr neurological survival (88% vs. 22%, p = .015) were higher with active compression-decompression cardiopulmonary resuscitation + an impedance threshold device. Cerebral perfusion pressures, measured in nine additional pigs, were improved with active compression-decompression cardiopulmonary resuscitation + an impedance threshold device (21.9 ± 1.2 mm Hg vs. 8.9 ± 0.8 mm Hg, p < .0001). With active compression-decompression cardiopulmonary resuscitation + impedance threshold device, mean diastolic intracranial pressure during decompression was lower (12.2 ± 0.2 mm Hg vs. 16.6 ± 1.2 mm Hg, p = .02) and the downward slope of the decompression phase intracranial pressure curve was steeper (-60.3 ± 12.9 mm Hg vs.-46.7 ± 11.1 mm Hg/sec, p < .001). Conclusions: Active compression-decompression cardiopulmonary resuscitation + an impedance threshold device increased cerebral perfusion pressures and lowered diastolic intracranial pressure and intracranial pressure rate during the decompression phase. These mechanisms may underlie the observed increase in cerebral perfusion pressure, carotid blood flow, and survival rates with favorable neurologic outcomes in this pig model of cardiac arrest. © 2012 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins. Source

Weil M.H.,Weil Institute of Critical Care Medicine
Critical care (London, England) | Year: 2011

Increases in blood lactate reflect decreases in systemic blood flows associated with low blood flow states characteristic of circulatory shock. Accordingly, the report by Vermeulen and colleagues documents the use of the blood lactate measurement as a prognostic indicator in settings of ST elevation myocardial infarction. That lactate value therefore identified high-risk patients as a complication, often with clinical signs of cardiogenic shock of corresponding severities. © 2011 BioMed Central Ltd Source

Weil M.H.,Weil Institute of Critical Care Medicine | Tang W.,Weil Institute of Critical Care Medicine
American Journal of Respiratory and Critical Care Medicine | Year: 2011

The evolution of Critical Care Medicine is traced in relationship to its predecessors, namely Intensive Care and Intensive Therapy. This commentary documents the initial physical care rendered by professional nurses in hospitals of the 19th century in locations close to the nursing stations. The development of incubators for newborns and life-support devices to support ventilation and renal function or to reverse fatal arrhythmias characterized Intensive Therapy of the early 20th century. In the most recent 50 years, Critical Care evolved for comprehensive, largely electronic monitoring and automated laboratory measurements to guide intensive therapy of multiorgan failures by critical care physicians and nurse specialists, pharmacists, and respiratory therapists using multiple life-support methodologies and devices. Source

Wu X.,Weil Institute of Critical Care Medicine | Bisera J.,Weil Institute of Critical Care Medicine | Tang W.,Weil Institute of Critical Care Medicine | Tang W.,University of Southern California
Resuscitation | Year: 2013

Objective: The possibility of successful defibrillation decreases with an increased duration of ventricular fibrillation (VF). Futile electrical shocks are inversely correlated with myocardial contractile function and long-term survival. Previous studies have demonstrated that various ECG waveform analyses predict the success of defibrillation. This study investigated whether the absolute amplitude of pre-shock VF waveform is likely to predict the success of defibrillation. Methods: ECG recordings of 350 out-of-hospital cardiac arrest (OOHCA) patients were obtained from the automated external defibrillator (AED) and analyzed by the method of signal integral. Successful defibrillation was defined as organized rhythm with heart rate ≥40. beat/min commencing within one min of post-shock period and persisting for a minimum of 30. s. Results: Signal integral was significantly greater in successful defibrillation than unsuccessful defibrillation (81.76. ±. 32.3. mV vs. 34.9. ±. 15.33. mV, p<. 0.001). The intersection of the sensitivity and specificity curve provided a threshold value of 51. mV. The corresponding values of sensitivity, specificity, positive predictive and negative predictive values for successful defibrillation were 90%, 86%, 80% and 93%, respectively. The receiver operator curve further revealed that signal integral predicted the likelihood of successful defibrillation (area under the curve. = 0.949). Conclusions: Signal integral predicted successful electrical shocks on patients with ventricular fibrillation and have potential to optimize the timing of defibrillation and reduce the number of electrical shocks. © 2013 Elsevier Ireland Ltd. Source

Li Y.,Weil Institute of Critical Care Medicine | Li Y.,Chongqing Medical University | Bisera J.,Weil Institute of Critical Care Medicine | Weil M.H.,Weil Institute of Critical Care Medicine | And 3 more authors.
IEEE Transactions on Biomedical Engineering | Year: 2012

Ventricular fibrillation (VF) is the primary arrhythmic event in the majority of patients suffering from sudden cardiac arrest. Attention has been focused on this particular rhythm since it is recognized that prompt therapy, especially electrical defibrillation, may lead to a successful outcome. However, current versions of automated external defibrillators (AEDs) mandate repetitive interruptions of chest compression for rhythm analyses since artifacts produced by chest compression during cardiopulmonary resuscitation (CPR) preclude reliable electrocardiographic (ECG) rhythm analysis. Yet, repetitive interruptions in chest compression are detrimental to the success of defibrillation. The capability for rhythm analysis without requiring hands-off intervals will allow for more effective resuscitation. In this paper, a novel continuous-wavelet-transformation-based morphology consistency evaluation algorithm was developed for the detection of disorganized VF from organized sinus rhythm (SR) without interrupting the ongoing chest compression. The performance of this method was evaluated on both uncorrupted and corrupted ECG signals recorded from AEDs obtained from out-of-hospital victims of cardiac arrest. A total of 232 patients and 31092 episodes of either VF or SR were accessed, in which 8195 episodes were corrupted by artifacts produced by chest compressions. We also compared the performance of this method with three other established algorithms, including VF filter, spectrum analysis, and complexity measurement. Even though there was a modest decrease in specificity and accuracy when chest compression artifact was present, the performance of this method was still superior to other reported methods for VF detection during uninterrupted CPR. © 2011 IEEE. Source

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