Circulatory shock
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Although it has been hypothesized that exogenously administered bicarbonate can exacerbate intramyocardial acidosis and compromise contractile function, this phenomenon has not been demonstrated in an intact model in which intramyocardial pH (pH(int)), regional venous pCO2, and regional contractile function have been simultaneously monitored. In 20 anesthetized dogs, we studied the effects of intracoronary infusions of sodium bicarbonate NaHCO3 30 mEg over 15 min, on regional pH(int), (glass electrode) and regional stroke work (SW, sonomicrometry) before and after creating systemic hypercarbic acidosis by hypoventilation. During NaHCO3 administration, regional coronary venous pCO2 increased rapidly during the first minute (eucapnea; 34 +/- 7 to 55 +/- 18 mm Hg; hypercapnea: 70 +/- 15 to 98 +/- 23 mm Hg, P < 0.05 for both increases). ⋯ To test the hypothesis that transient intracellular acidosis during bicarbonate infusions was underestimated by measurements of pH(int), measurements of intracellular pH using the pH-sensitive dye, BCECF, were performed in isolated guinea pig papillary muscles incubated in vitro. These measurements confirmed the presence of transient intracellular acidosis during bicarbonate infusion. In conclusion, (1) the intracoronary administration of sodium bicarbonate causes a transient depression in myocardial contractile function that is related to transient intracellular acidosis; and (2) despite exacerbating hypercarbia, sodium bicarbonate ultimately neutralizes intracellular acid and augments myocardial contractile function.
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Peritonitis and septic shock may lead to tissue hypoxia, but this risk is not identical in all organ systems. This study was undertaken to measure changes in tissue oxygenation and perfusion in the gut wall and subcutaneous tissue, respectively, and to examine their relation to oxygen delivery and consumption. Twelve pigs were anesthesized and mechanically ventilated. ⋯ The animals were then followed for 5 hr. pHi remained stable in the control group, whereas a drop from 7.37 to 7.02 took place in the peritonitis group. In the test group, subcutaneous oxygen tension (PscO2) already began to fall 1 hr after the induction of peritonitis, and gained the minimum at the end of the study. In peritonitis, a moderate correlation was seen between pHi and DO2 (r = 0.51 +/- 0.16); no statistical difference was noted if pHi was correlated to gut DO2 (r = 0.56 +/- 0.18).(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study Clinical Trial Controlled Clinical Trial
A comparison of pentastarch and lactated Ringer's solution in the resuscitation of patients with hemorrhagic shock.
Pentastarch is a colloid that is chemically similar to Hetastarch. It has a shorter half-life (12 hr), and produces volume expansion at least 1.5 times the administered volume. We compared Pentastarch to Ringer's lactate in 41 patients (21 Pentastarch, 20 Ringer's lactate) presenting with hemorrhagic shock. ⋯ Serum albumin was the same in both groups throughout the study period; however, serum colloid oncotic pressure was elevated at 1 hr post-resuscitation in the Pentastarch group (P < 0.005). There was no difference in ventilatory parameters, blood gases, pulmonary function tests, ventilator days, or hospital days between the two groups. We conclude that Pentastarch is safe and effective for the initial resuscitation from hemorrhagic shock.
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Comparative Study
Comparison of effects of dopamine hydrochloride and dopexamine hydrochloride on abdominal and femoral hemodynamics in anesthetized dogs.
The effects of dopamine and dopexamine administered in graded intravenous bolus injections (0.1-51.2 micrograms.kg-1) were compared in the renal and femoral, and in a number of splanchnic vessels at the organ level simultaneously in anesthetized dogs. Hemodynamic data are presented for each artery as conductance, which was obtained by dividing mean flow by mean arterial pressure. The data were analyzed in two different ways: 1) by responses at intervals of 3 sec to 12.8 micrograms dopamine or dopexamine during 1 min, and 2) by dose-response curves. ⋯ Dopexamine decreased aortic pressure. Low dosages of dopexamine increased urine production, without raising renal blood flow. An advantage of dopexamine over dopamine could be that dopexamine does not stimulate alpha-adrenergic receptors.
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Anesthetized and ventilated swine were bled 23 ml/kg (34% of calculated blood volume) to a mean arterial pressure < 50 mm Hg. After 60 min, a bolus of either 7.5% hypertonic saline/6% dextran 70 (HSD, 4 ml/kg x 5 min) or lactated Ringer's (LR, 32 ml/kg x 5 min) was infused i.v. LR (25-30 ml/kg) was administered to all animals for the next 60 min. ⋯ Furthermore, systemic oxygen consumptions were significantly higher, and intracranial pressures were each significantly lower with HSD. Nevertheless, no variables were far outside the normal range in either group. The addition of AICAR to LR and HSD eliminated the difference in intracranial pressure, systemic oxygen consumption, reduced heart rate by 30-40 beats/min during the first hour of resuscitation, and increased stroke volume by 20-30%.(ABSTRACT TRUNCATED AT 250 WORDS)