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Biomedical subjects

C Escudero

Publications and source records attributed to C Escudero.

42 records · Page 3Linked to original sources
PubMed1989

Sinus node function and protamine sulfate.

This report analyzes the effects of protamine sulfate (PS) on the heart rate and sinoatrial node function in dogs anesthetized with diazepam, fentanyl, and pancuronium bromide, and subjected to different modalities of extracorporeal circulation (ECC). All groups were given 3 mg/kg of heparin sodium and 5 mg/kg of PS. The sinus node function was evaluated by means of sinoatrial conduction time (SACT), absolute sinus node recovery time (SNRTa), and corrected sinus node recovery time (SNRTc). The spontaneous heart rate (HR) of the animals was also analyzed. Under the experimental conditions established in this study, the intravenous administration of a bolus of PS produced a decrease in the HR in all the groups, regardless of the type of ECC used. The modifications in the conduction and recovery times of the sinus node by PS did not correlate with those of the heart rate; the sinoatrial conduction time increased in groups subjected to ECC, while the absolute and corrected recovery times of the sinus node were prolonged only in the group that underwent rapid rewarming.

Animals↗
PubMed1988

Hemodynamic and morphologic alterations after experimental administration of protamine sulfate.

The hemodynamic, hematologic, and morphologic effects induced by protamine sulfate have been studied in 28 dogs divided into 6 groups. All of the groups were given heparin (3 mg/kg body weight) and Groups I, II, III, and IV were given protamine (5 mg/kg body weight). Group I (control group) was not subjected to extracorporeal circulation. The other groups had the following interventions: Group II, cardiopulmonary bypass without aortic clamp, hypothermia, or cardioplegia; Groups III and V, hypothermia of 25 degrees C, aortic clamping for 25 minutes, administration of cardioplegic solution, and slow rewarming; and Groups IV and VI, the same as Groups III and V, but with rapid rewarming. After injection of protamine sulfate, there was a decrease in mean arterial pressure due to peripheral vasodilation and an increase in the mean pulmonary pressure due to increased pulmonary vascular resistance; marked diminution of the number of circulating platelets aside from the extracorporeal circulation; a decrease in the contractility of both ventricles with augmented right ventricular work and decreased cardiac output; and right ventricular edema in Groups I, II, III, and IV. These alterations were most evident in Groups III and IV.

Animals↗
PubMed1987

Coagulation defects during extracorporeal circulation in the dog.

This study was undertaken in an attempt to diminish the frequency and severity of postextracorporeal circulation hemorrhage in dogs. Its purpose is to ascertain the amount of 99mTc-labeled autologous fibrinogen deposited in the oxygenator, as well as the coagulation defect originated during the surgical procedure when heparin is not administered (group I) and when it is at doses of 1 mg/kg body weight (group II) and 3 mg/kg body weight (group III). The result demonstrate that the fibrinogen deposition in the oxygenator decreased as the dose of heparin administered was augmented. The coagulation disorders were produced by factor consumption, affecting all dogs in group I. The same type of alteration was produced with the use of heparin, but in some the platelet count, fibrinogen and fibrinogen degradation products and the prothrombin and thrombin times were maintained within normality or were only slightly altered. Significant differences were not detected between groups II and III. For this reason, we recommend the utilization of heparin in experimental extracorporeal circulation in a single dose of 1 mg/kg body weight, administered at the initiation of bypass, which provides a sufficient level of anticoagulation for at least 60 min and makes its neutralization with protamine unnecessary, the effects of which are especially adverse in the dog.

Animals↗
PubMedDate not supplied

Effects of different doses of acetylsalicylic acid on platelet aggregation: an experimental study of prosthetic materials in dogs.

Laminar flow is the condition best suited to the study of platelet thrombi. This type of thrombus is predominant in arteries, in the tubes of cannulas used in artificial circulatory systems, in cardiac valve prostheses and in prosthetic arterial implants. Antiplatelet drugs could, in these cases, reduce the extent of thrombus formation. At present the optimal dose of acetylsalicylic acid (ASA) to achieve the best antithrombotic effect is unknown; some papers show that high doses augment experimental thrombosis. By means of autologous platelets labelled with 111In-oxine, we have quantified the accumulation on different materials used in cardiovascular surgery (woven, knitted and double velour Dacron, Avcothane 51 elastomere and smooth surface and rough surface pericardium). Samples of these fabrics were placed in a laminar flow chamber connected between the right atrium and femoral artery of the experimental animals (dogs). The animals were divided into four groups of eight dogs: Group I: no treatment Group II: animals treated one week earlier with ASA (1 mg/kg/day) Group III: as in Group II, but at a dose of 5 mg/kg/day Group IV: as in Group II, but at a dose of 20 mg/kg/day. The materials upon which the least amount of platelets were accumulated were the smooth, epicardial surface of pericardium (SP) and Avcothane (AV). The least deposition was produced in Group III, with the exception of SP. In the case of this material, there was no difference between Groups I and III. In Group IV, the deposit was greater with respect to the untreated group (Group I), except in the case of AV, in which there was no difference between Groups I and IV.

Animals↗
PubMedDate not supplied

Design of a laminar flow chamber to study platelet aggregation.

The growing importance of the utilization of artificial materials in cardiovascular surgery makes it necessary to know their thrombogenic capacity. Our flow chamber, which is constructed of methacrylate, is capable of providing a laminar flow. The chamber itself consists of the trunks of two cones, one for the inflow and the other for the outflow, which are joined at their widest point to the ends of a cylinder of the same diameter. In the interior of the cylinder, which constitutes the central part of the system, are placed three rectangular fragments of the material to be studied. The vertices of the trunks of the cones allow the coupling of two flexible siliconized tubes in such a way that the system can be utilized in an "ex vivo' experimental model, constituting a bridge between the femoral artery and the right atrium of a large experimental animal, as well as in vitro, coupled to a continuous perfusion pump. The advantages provided by this system are that: (a) three materials can be studied simultaneously in an identical situation, (b) it is possible to submit these materials to conditions similar to those that give rise to platelet thrombi, and (c) it is possible to quantify the aggregation on each material by labelling the platelets with 111In-oxine.

Biocompatible Materials↗