Resuscitation
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Comparative Study
Tracheal epinephrine or norepinephrine preceded by beta blockade in a dog model. Can beta blockade bestow any benefits?
Tracheal epinephrine (adrenaline) has been associated with two major deletorious side effects: increased heart rate (HR) and an initial decrease of blood pressure (BP). This prospective randomized animal study compared the haemodynamic responses to tracheally administered epinephrine or norepinephrine (nor adrenaline) alone versus each after pretreatment with propranolol for ameliorating those two untoward effects associated with epinephrine administration. Five anaesthetized mongrel dogs underwent 25 experiments of tracheal epinephrine or norepinephrine (0.02 mg/kg diluted with normal saline to 5 ml total volume) with or without an I/V non-selective beta-blocker (propranolol 0.1 mg/kg) pretreatment, and served as their own controls. ⋯ While both epinephrine or norepinephrine after pretreatment with propranolol produced a significant increase in both diastolic (from 106 to 166 mmHg and from 118 to 169 mmHg, respectively) (P<0.01) and mean BP (from 122 to 183 mmHg and from 133 to 188 mmHg, respectively) (P<0.01), only propranolol-pretreated tracheal epinephrine yielded a significant decrease in HR (from 52 to 33/m, P=0.002). Pretreatment with a beta-blocker protected against the deleterious tachycardia associated with epinephrine or norepinephrine and, by doing so, may improve the myocardial oxygen supply-and-demand balance. At the same time, the pretreatment augmented the relatively mild diastolic BP increase associated with the beta-adrenergic effect of epinephrine.
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Acidosis may contribute to brain injury from asphyxia, but its role is unclear. In order to evaluate the association between brain acidosis and cerebral injury, we subjected piglets to hypoxia and hypotension (HYP-HOTN) or hypoxia alone (HYP) to inflict varying amounts of brain damage. We hypothesized that piglets with a more severe brain injury would have a lower brain pH. ⋯ The time needed for brain pH to recover after asphyxia, but not its severity, was associated with the amount of brain injury. Further study is warranted to determine whether immediate restoration of brain pH will reduce brain damage.
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Comparative Study
Brain metabolism during cardiopulmonary resuscitation assessed with microdialysis.
Microdialysis is an established tool to analyse tissue biochemistry, but the value of this technique to monitor cardiopulmonary resuscitation (CPR) effects on cerebral metabolism is unknown. The purpose of this study was to assess the effects of active-compression-decompression (ACD) CPR in combination with an inspiratory threshold valve (ITV) (=experimental CPR) vs. standard CPR on cerebral metabolism measured with microdialysis. ⋯ Using the technique of microdialysis we were able to measure changes of brain biochemistry during and after the very special situation of hypothermic cardiopulmonary arrest. Experimental CPR improved the lactate-pyruvate ratio, and glucose metabolism.
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Comparative Study
Immediate defibrillation versus interventions first in a swine model of prolonged ventricular fibrillation.
we compared time-dependent rescue shock success when delivered immediately, to defibrillation preceded by 3 min of CPR, with and without high dose epinephrine (HDE) in a swine model of prolonged ventricular fibrillation (VF). Our hypotheses were that pretreatment with CPR and HDE would produce higher rates of successful first-shock defibrillation and would prevent decay of the VF waveform, as measured by the scaling exponent (ScE), when compared to immediate defibrillation. We also sought to determine the predictive value of the ScE in determining post-shock outcomes. ⋯ HDE-11 showed a tendency for producing a higher rate of first-shock success and ROSC. Interventions prior to rescue shock prevented deterioration of the VF waveform and improved rescue shock outcomes. The ScE accurately predicted 81-85% of post-rescue shock outcomes.