Cardiology clinics
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The importance of vital organ perfusion in patients suffering cardiac arrest makes arterial vasomotor tone, and the resultant perfusion pressure, critical in resuscitation from sudden death. Although there are multiple mechanisms that may affect arterial vascular tone, historically, the therapy most commonly used has been catecholamine-induced adrenergic receptor stimulation, with catecholamine epinephrine being the commonest drug used. Over the last decade, however, it has become widely known that the utility of epinephrine during cardiopulmonary resuscitation is undefined. ⋯ Other agents appear promising. This article addresses pressor drugs and adrenergic agonists, including a review of their history, basic science, mechanism of action, and efficacy. Epinephrine is reviewed.
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Airway management is fundamental to ACLS. Success with any airway device relies as much on the operator's experience and skill as on the device itself. ⋯ If airway intervention is to have a positive effect on outcome, the choice of airway device is less important than thorough training, ongoing experience and review, and close attention to complications. Regardless of whether a provider chooses to use the LMA, the combitube, or the tracheal tube, providers must be familiar with more than one method of airway management because of the possibility of failure to insert or ventilate with their primary airway device of choice.
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Principles of cardiovascular physiology tell us that during cardiac arrest and CPR, forward flow of blood can be generated by external compression or decompression of either the chest or the abdomen. Standard CPR utilizes only one of these modes--chest compression--and generates roughly 1 L/min forward flow in an adult human, which is 20% of normal cardiac output. IAC-CPR uses two of these modes--chest compression and abdominal compression--and generates roughly twice the forward flow, or 2 L/min in an adult human. ⋯ Theoretically, full four-phase CPR, including active compression and decompression of both chest and abdomen, is capable of generating 4 L/min forward flow or greater, which is 80% of normal, and there is a reasonable prospect of achieving 100% of normal flow under conditions in which all four phases are optimized. Standard CPR is clearly not the ultimate form of external CPR. There is real, credible evidence that substantial improvements in resuscitation methods and results will be possible in the next decade.
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Postresuscitation myocardial dysfunction is common after prolonged cardiac arrest and can have life-threatening consequences. Experimental data suggest that systolic and diastolic left ventricular function can be adversely effected following successful resuscitation. ⋯ Potential treatments include dobutamine, KATP channel activators, and 21-aminosteroids. In the author's efforts to improve long-term survival from cardiac arrest, more attention is needed to the postresuscitation period.
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CPR represents the primary intervention used during cardiac arrest for maintaining perfusion and extending the potential resuscitation period. Effective CPR, however, requires careful attention to detail by the resuscitation team, including (1) effective control of the airway using manual maneuvers or airway adjuncts, (2) delivery of effective ventilation that assures adequate oxygenation, while reducing the chance for gastric inflation, and (3) chest compressions delivered at the appropriate depth and rate using a duty cycle of 50% compression and 50% release. During the resuscitation effort team leaders should closely monitor the performance of CPR, rotate rescuers frequently to avoid fatigue, and provide continuous feedback based upon direct (transmitted pulse, chest rise) and indirect (end-tidal CO2) measures of effectiveness. A careful and measured approach to CPR performance, combined with a strong chain of survival, provides victims of cardiac arrest the best chance for survival.