Resuscitation
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Open-chest cardiac massage (OC-CM) provides higher blood pressure and flow than closed-chest compression and may improve the probability of successful resuscitation from cardiac arrest. Its clinical use has been limited by its requirement for a major thoracotomy. The present pilot study tested the technical feasibility of performing effective direct cardiac massage without a major thoracic incision, by using a simple, manually-powered plunger-like device, inserted through a small thoracic incision, to cyclically compress the cardiac ventricles. The method was termed minimally-invasive direct cardiac massage (MID-CM). Systemic blood flow using MID-CM was compared to that with OC-CM, by both direct systemic hemodynamic measurements, cumulative metabolic indicators of the ratio of whole body oxygen delivery and oxygen consumption, and a metabolic index of pulmonary blood flow. ⋯ Systemic Blood Pressure: Aortic systolic and diastolic blood pressures were reduced from baseline levels with both OC-CM and MID-CM. No difference in pressure was noted between OC-CM and MID-CM groups. Pulmonary Artery Pressure: Pulmonary artery systolic pressure was elevated from baseline during OC-CM and MID-CM. Pulmonary artery diastolic pressures remained constant throughout the resuscitation period in both groups. No differences in pulmonary systolic or diastolic pressure were noted between OC-CM and MID-CM groups. A trend towards higher pulmonary systolic pressures appeared with MID-CM. Thermodilution Blood Flow: Cardiac index fell from baseline levels with OC-CM and MID-CM. No difference in cardiac index was noted between OC-CM and MID-CM groups. Metabolic Indices: Mixed venous O2 saturation decreased from baseline levels during resuscitation in both experimental groups, with a further decrease at 30 min compared to 10- and 20-min levels. No difference was noted between OC-CM and MID-CM groups at any point. Arterial pH was reduced from baseline levels at 30 min in both groups compared to baseline but no difference was noted between groups.(ABSTRACT TRUNCATED AT 400 WORDS)
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Comparative Study
Adrenaline in out-of-hospital ventricular fibrillation. Does it make any difference?
A large proportion of cardiac arrests outside hospital are caused by ventricular fibrillation. Although it is frequently used, the exact role of treatment with adrenaline in these patients remains to be determined. ⋯ On the basis of 2 treatment regimens during a 12-year survey, we explored the usefulness of adrenaline in out-of-hospital ventricular fibrillation. Both patients with sustained ventricular fibrillation and those who converted to asystole or electromechanical dissociation had an initially more favourable outcome if treated with adrenaline. However, the final outcome was not significantly affected. This study does not confirm the hypothesis that adrenaline increases survival among patients with out-of-hospital cardiac arrest who are found in ventricular fibrillation.
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Comparative Study
Hypoxic cardiopulmonary-cerebral resuscitation fails to improve neurological outcome following cardiac arrest in dogs.
Hyperoxic cardiopulmonary resuscitation (CPR) is associated with an increase in neurologic dysfunction upon successful resuscitation with much of the damage attributable to an increase in reperfusion oxidant injury. We hypothesized that by contrast, hypoxic ventilation during resuscitation would improve neurologic outcome by reducing available substrate necessary for oxidant injury. Specifically, this study investigated the effects of 2 levels of hypoxic ventilation during resuscitation: F1O2 = 0.085, PaO2 = 26.6 +/- 3.4 mmHg, (HY8), and F1O2 = 0.12, PaO2 = 33.0 +/- 4.2 mmHg, (HY12), and normoxic resuscitation: F1O2 = 0.21, PaO2 = 60.6 +/- 17.0 mmHg, (N) on survival and neurological outcome following 9 min of normothermic cardiac arrest. ⋯ Pooled data for GSH showed a significant drop at 1 h following resuscitation and returned to normal by 6 h. Data from these markers suggested attendant oxidant injury in all groups. Thus, hypoxic ventilation at 2 depths of hypoxia during resuscitation failed to improve neurologic outcome beyond that achieved by ventilation with air, suggesting that normoxia rather than hyperoxia or hypoxia is the ideal target for arterial oxygenation during resuscitation.
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Comparative Study
Combined continuous monitoring of systemic and cerebral oxygen metabolism after cardiac arrest.
Cerebral oxygenation was assessed in 8 patients in cardiac arrest during the 24 h after resuscitation, by continuous fiber-optic monitoring of jugular bulb venous oxygen saturation (SjO2), in conjunction with continuous monitoring of mixed venous oxygen saturation (SvO2). Three patients survived and 5 died. SjO2 and SvO2 patterns were compared between surviving and non-surviving patients with regard to their prognostic and therapeutic implications. ⋯ The high SjO2 of the non-survivors suggests that an inability of damaged neurons to use oxygen may be an indicator of poor neurological outcome in resuscitated patients after cardiac arrest. When SjO2 was < 45%, Sv-O2 was extremely low, reflecting cardiovascular failure after resuscitation. SjO2 may thus serve to warn of deterioration in cardiopulmonary function and serve as a predictor of outcome in cardiac arrest survivors.
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Although high-dose epinephrine during CPR improves coronary perfusion pressure (CoPP) and rate of return of spontaneous circulation (ROSC) in some models, its impact on long term outcome (> or = 72 h) has not been evaluated. Previous studies of sodium bicarbonate (NaHCO3) therapy during CPR indicate that beneficial effects may be dependent on epinephrine (EPI) dose. We hypothesized that EPI and NaHCO3 given during CPR have a significant impact on long term outcome. ⋯ There was an overall trend toward improved survival at 72 h in rats that received NaHCO3 which was most evident in the EPI 0.1 mg/kg group. We conclude that (1) EPI during CPR has a biphasic dose/response curve in terms of survival, when post-resuscitation effects are left untreated and (2) NaHCO3 doses greater than 1.0 mEq/kg may be necessary to treat the side-effects of high-dose EPI. Further work is needed to determine if treating the immediate post-resuscitation effects of high-dose EPI can prevent detrimental effects on long-term outcome.