Resuscitation
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Comparative Study
Biphasic and monophasic transthoracic defibrillation in pigs with acute left ventricular dysfunction.
Our purpose was to compare biphasic versus monophasic shock success for VF termination in a porcine model of acute left ventricular (LV) dysfunction. ⋯ In this porcine model of acute LV dysfunction, biphasic waveform shocks were not only superior to monophasic waveform shocks for termination of VF during baseline, but retained superiority to monophasic waveform shocks when LV dysfunction was present.
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The mechanism of forward blood flow during cardiopulmonary resuscitation (CPR) remains controversial. We hypothesized that, if the heart acts as a pump, the proximal descending thoracic aorta would be distended during compression by forward blood flow, and would be constricted or remained unchanged if blood flow is generated by increased intrathoracic pressure. Fourteen patients with nontraumatic cardiac arrest underwent transesophageal echocardiography to verify changes in the descending thoracic aorta during standard manual CPR. ⋯ The deformation ratio of the descending thoracic aorta proximal to the maximal compression site remained unchanged during compression and relaxation (1.0+/-0.88 vs. 1.0+/-0.9, P=0.345). The cross-sectional area of the descending thoracic aorta proximal to the maximal compression site increased 15% on average during compression compared with relaxation in 12 of 14 patients. In conclusion, deformation of the aorta at the maximal compression site and increase in the cross-sectional area of the proximal aorta suggests that cardiac pumping is the dominant mechanism in generating forward blood flow during CPR in humans.
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Randomized Controlled Trial Comparative Study Clinical Trial
Randomised controlled trials of staged teaching for basic life support: 2. Comparison of CPR performance and skill retention using either staged instruction or conventional training.
Teaching CPR in stages is a strategy designed to improve skill acquisition and retention. This method has been compared with conventional teaching in a randomised trial involving 495 volunteers. The first ('bronze') stage was simplified by omitting ventilation and giving compressions in sets of 50 with pauses to open the victim's airway; in the second ('silver') stage ventilation was introduced in a ratio of 50 compressions to five breaths, and in the third ('gold') stage, the volunteers were converted to conventional CPR. 51% of those taught by this method reattended for the second ('silver') stage compared with 25% who were taught conventional CPR and advised to return for a revision session. 38% of the staged group reattended for the third ('gold') compared with 8% for the conventional group. ⋯ The increased number of compressions that can be achieved by teaching 'bronze' stage CPR with no ventilation was retained, to a lesser degree, when the 'silver' ratio of 50 compressions to five breaths was compared with the conventional 15:2 ratio. Our observations suggest that during the first critical 8 min of a resuscitation attempt, 58% more compressions might be delivered by using the 50:5 ratio - an increase that is likely to result in a significant augmentation of blood flow with important clinical implications. More comparative information will become available when the results of unannounced home testing are analysed.
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Mean fibrillation frequency may predict defibrillation success during cardiopulmonary resuscitation (CPR). N(alpha)-histogram analysis should be investigated as an alternative. ⋯ During the last minute prior to defibrillation, histogramstart/histogramwidth of > or =2.3 versus mean fibrillation frequency > or =8 Hz predicted successful defibrillation with subsequent return of a spontaneous circulation for more than 60 min with sensitivity, specificity, positive predictive value and negative predictive value of 94 versus 82%, 96 versus 89%, 98 versus 93% and 90 versus 74%, respectively. We conclude, that N(alpha)-analysis was superior to mean fibrillation frequency analysis during CPR in predicting defibrillation success, and distinction between vasopressin versus epinephrine effects.
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Thrombolytic therapy during cardiopulmonary resuscitation (CPR) is a controversial issue in emergency medicine practice. This study was conducted to determine whether administration of recombinant tissue plasminogen activator (rt-PA) in out-of-hospital cardiac arrest of non-traumatic aetiology improves CPR outcome. ⋯ Thrombolytic therapy may improve frequency of return of spontaneous circulation substantially and increase primary survival in patients with non-traumatic cardiac arrest. Serious bleeding complications are not frequently observed under rt-PA treatment.