Hemodynarnic Changes after Superior Mesenteric Artery Occlusion in Dogs / 第三军医大学学报

In order to study the characteristics of the early cardiovascular responses following the occlusion of the superior mesenteric artery, occlusion of the artery was perfomed on 7 dogs, and sham operation on 6 dogs to serve as control- It was found that after the release of the occlusion 2 hours later, the mean arterial pressure and the central venous pressure of the experimental group dropped significantly. Comparable changes could not be observed in the controls. Meanwhile, the parameters of left ventricular functions such as left ventricular systolic pressure, + dp/dt max, = dp/dt max, Q-dp/dt max interval, and the product of 3 items(cardiac rate, Q-dp/d max interval and the peak value of left ventricular pressuure) showed no difference between the 2 groups.The results suggest that the general functional derangement of the cardiovascular system can be ascribed to the pooling of blood and/or fluid in the splanchnic area, and the adnormal myocardial performance does not appear in the initial phase of superior mesentric artery occlusion.

Acid-Base Balance Responses of Acute Graded Hemorrhage in Dogs / 第三军医大学学报

On 8 dogs a moderate hypotension is produced by stcpwisc blood loss of 24ml/kg for 60 min At the end of this period the shed blood is rcinfuscd back in the animal.Results of observation after 60 min demonstrate a significant (p

Effects of Calcium Gluconate on Cardiovascular Functions, Oxygen Transport and Acid-base Balance during Hemorrhagic Shock in Dogs / 第三军医大学学报

Hemorrhagic shock was induced in 13 dogs with modified Wigger's method to maintain the mean arterial pressure at 5.33kPa for 60 minutes. 6 dogs were treated with 10% calcium gluconate 0.15ml/kg intravenously at the 60th, 70th, and 80th minute of the oligemic period respectively, while 7 dogs received an equal volume of normal saline at the corresponding time. At the 90th minute of the oligemic period, the shed blood was transfused back to the animals.During the 90-minute oligemic shock period, the mean arterial pressure, the peak value of the left ventricle systolic pressure, + dp/dtmax and total peripheral resistance of the treated dogs were significantly higher than those of the controls, but the heart rate, cardiac index, - dt/dtmax and myocardial oxygen consumption showed no significant difference between the 2 groups. After the transfusion of the shed blood back to the animals, no apparent difference of any of the above-mentioned parameters between the 2 groups could be found. In both groups, the oxygen delivery, oxygen consumption, oxygen extract ration and pH value were similar during the oligemic period and after the back-transfusion of the shed blood.The results indicate that exogenous calcium infusion cannot bring about any beneficial effects on the cardiovascular functions, oxygen transport and acid-base balance during hemorrhagic shock.

Hemodynamic Changes after Oleic Acid Induced Lung Damage in Dogs / 第三军医大学学报

In order to study the characteristics of the early cardiovascular responses after oleic acid induced lung damage, oleic acid (OA) 0.1ml/kg body weight was infused intravenously into 11 anesthetized and artificially ventilated dogs, and the effects were observed for 3 hours. After OA infusion, PaO2 decreased progressively to a fairly low level with a coincident increase of the alveolar-arterial PO2 gradient and decrease of the oxygen delivery. Cardiac index gradually decreased and reached only 49% of the baseline value at 180 minutes after OA injection. Mean systemic arterial pressure decreased transiently at 60 minutes after OA injection without concomitant increase of the pulmonary arterial pressure. The left ventricular stroke work, +dp/dtmax and - dp/dtmax, and the impedance contractility index were inhibited throughout the experiment. The postmortem lung-body ratio was significantly increased.These results suggest that the dogs following OA injection exhibit severe hypoxemia, reduced cardiae output, suboptimal cardiac performance and reduced oxygen delivery; the reduced cardiac outpur is associated with early and sustained inhibition of the myocardial contractility; and the pulmonary arterial pressure does not change significantly in the whole course of the experiment, so the edema formation does not result from the increase of the capillary hydrostatic pressure.

Effect of Intravenous Glucose-Insulin-Potassium on Cardiovascular Functions during Acute Hypoxia / 第三军医大学学报

The effect of intravenous infusion of glucose-insulin-potassium (G1K) on the cardiovascular functions during acute hypoxia was studied and was compared with that of normal saline(NS). 14 anesthetized dogs were forced to inhale a hypoxic gas mixture. After the first ten-minute inhalation, Pao2 and total peripheral vascular resistance decreased to 29~3l% and 66-67% of the pre-in-halation levels respectively while the pulmonary arterial pressure increased 43-49%. Then a bolus injection of GIK was given to 8 dogs, and an injection of NS to 6 dogs. Hypoxic gas inhalation was continued for 20 more minutes. 5 -10 minutes after GIK injection, the mean arterial pressure, cardiac output, stroke volume, stroke work , and left ventricular pressure all significantly increased, however, no apparent changes could be observed in any of the above mentioned parameters after NS injection. This result reveals that cardiovascular functions during acute hypoxia can be rapidly, markedly but temporarily improved when a small volume of GIK is administered intravenously.