Resuscitation
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To evaluate how often an ambulance crew reports abnormal breathing among patients who are found deeply unconscious but without having suffered a cardiac arrest. ⋯ Signs of abnormal breathing among comatose patients with no cardiac arrest appear to be relatively common. This therefore increases the risk of starting cardiopulmonary resuscitation (CPR) in such patients, which is in accordance with the present CPR guidelines for the lay person. Whether this might do harm to such patients is not known.
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Sequential monophasic defibrillation reduces transthoracic impedance (TTI) and progressively increases current flow for any given energy level. The effect of sequential biphasic shocks on TTI is unknown. We therefore studied patients undergoing elective cardioversion using a biphasic waveform to establish whether this is a phenomenon seen in the clinical setting. ⋯ Sequential biphasic defibrillation decreases TTI in a similar manner to that seen with monophasic waveforms. The effect is likely during defibrillation during cardiac arrest by the quick succession in which shocks are delivered and the lack of cutaneous blood flow which limits the inflammatory response. The ability of biphasic defibrillators to adjust their waveform according to TTI is likely to minimise any effect of these findings on defibrillation efficacy.
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The incidence of pulseless electrical activity (PEA) as a presenting rhythm during cardiac arrest is increasing. The current animal models of PEA arrest, post-countershock or total asphyxiation, unreliably generate PEA for a specific time period. Neither of these models predictably generate pseudo-PEA. The purpose of this study was to create an animal model of pseudo-PEA that will allow for a prolonged time period in this arrest state for future research. ⋯ Partial asphyxiation using a 16% oxygen/84% nitrogen mix is a reliable laboratory method to create a prolonged state of pseudo-PEA in a swine model. The mechanism generating pseudo-PEA is hypoxemia-induced systemic acidosis. This model will allow sufficient time in this low-flow cardiac state for future research to be conducted.