Resuscitation
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The effects of three anesthetic regimens on an established model of pediatric porcine hypoxic-hypercarbic arrest were examined. Twenty-four preadolescent miniature piglets were paralyzed, mechanically ventilated and anesthetized with one of three regimens: IM + IV pentobarbital (n = 8); IM + IV ketamine (n = 8); or IM ketamine+inhaled isoflurane (n = 8). Asphyxial cardiopulmonary arrest was induced and, after and 8 min cardiac arrest nonintervention interval, a standardized protocol of manual CPR with mechanical ventilation was performed. ⋯ As designed and expected, return of spontaneous circulation did not occur in any animal. We conclude that, in developing models of porcine asphyxial cardiopulmonary arrest and resuscitation to simulate pediatric human arrest, variations in anesthetic regimen produce significant differences in parameters that are important to consider: time to asphyxia induced cardiac arrest, fibrillation threshold, plasma epinephrine level and arteriovenous epinephrine gradient. Anesthetic effects need to be carefully considered and clearly explained to facilitate the interpretation of studies of interventions in cardiopulmonary arrest and resuscitation.
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Comparative Study
Effects of the AT1-selective angiotensin II antagonist, telmisartan, on hemodynamics and ventricular function after cardiopulmonary resuscitation in pigs.
The purpose of this study was to investigate the effects of the angiotensin II (ANG II) antagonist, telmisartan, on hemodynamics, myocardial function and myocardial blood flow during the postresuscitation phase in a porcine model of CPR and to compare these to saline. After 4 min of ventricular fibrillation and 5 min of closed-chest CPR, defibrillation was performed in 16 domestic pigs to restore spontaneous circulation (ROSC). Ten minutes after ROSC, animals were allocated to receive either the ANG II antagonist, telmisartan, at a dose of 1 mg/kg (n = 8) or saline (n = 8). ⋯ M.), 42 +/- 4 ml, 38 +/- 2%, 2036 +/- 77 mmHg/s in the telmisartan group and 82 +/- 2 ml (P < 0.05), 59 +/- 3 ml (P < 0.01), 28 +/- 2% (P < 0.01), 1596 +/- 82 mmHg/s (P < 0.01) in the control group, at 240 min after ROSC. No significant differences in mean aortic and pulmonary artery pressure, cardiac index or myocardial blood flow between the two groups were found. We conclude that the ANG II antagonist telmisartan administered during the postresuscitation phase in pigs increases myocardial contractility without changing cardiac index, systemic vascular resistance, pulmonary vascular resistance, or myocardial perfusion.
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American Heart Association as well as European Resuscitation Council require the carotid pulse check to determine pulselessness in an unconscious victim and to decide whether or not cardiopulmonary resuscitation (CPR) should be initiated. Recent studies on the ability of health professionals to check the carotid pulse have called this diagnostic tool in question and led to discussions. To contribute to this discussion we performed a study to evaluate skills of lay people in checking the carotid pulse. ⋯ Only 47.4% of the volunteers were able to detect a pulse within 5 s, and 73.7% within 10 s. A level of 95% volunteers detecting the pulse correctly was reached only after 35 s. Based on these findings we conclude that the intervals established for carotid pulse check may be too short and that perhaps the value of pulse check within in the scope of CPR needs to be reconsidered.
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Comparative Study
Open-chest cardiac massage without major thoracotomy: metabolic indicators of coronary and cerebral perfusion.
To compare the coronary and cerebral perfusion achieved using a novel method of minimally-invasive, direct cardiac massage to that obtained using bimanual, open-chest cardiac massage. ⋯ Minimally-invasive, direct cardiac massage provides coronary and cerebral perfusion similar to that achieved using standard open-chest cardiac massage. This method may provide a more effective substitute for standard, closed-chest cardiac massage in cases of refractory cardiac arrest.
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The aim of the study was to compare the effect of a 30 and 50% duty cycle on coronary perfusion pressure (CPP) and end tidal carbon dioxide (ETCO2) and to determine whether a duty cycle of 30% can be achieved manually. After 3 min of ventricular fibrillation cardiac arrest, pigs were resuscitated in two groups with changing duty cycles every 3 min: group A starting with 50 and then 30%; and group B starting with 30 and then 50%. After administration of epinephrine, duty cycles in group A were 50 and then 30%, in group B initially 30% and then 50% Before administration of epinephrine, no significant differences in CPP between the 30 and 50% duty cycles were found; after epinephrine CPP increased with both duty cycles. ⋯ Survival was 4/6 in group A and 3/5 in group B (NS). It is possible to perform a manual duty cycle of 30%. However, our data do not support the use of a 30% duty cycle during cardiopulmonary resuscitation (CPR).