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Biomedical subjects

R Demeyere

Publications and source records attributed to R Demeyere.

15 recordsLinked to original sources
PubMed1998

Lipoprotein(a) changes during and after coronary artery bypass grafting: an epiphenomenon?

The lipoprotein(a) (Lp(a)) time course during and after coronary artery bypass grafting was examined in 20 caucasoid patients, in relation to the time courses of serum cholesterol and serum triglycerides. Samples were taken at eight different time points. Baseline geometric means (SD) for Lp(a), cholesterol and triglycerides were 115 (336) mg/L, 5.73 (1.10) mmol/L and 1.73 (1.21) mmol/L, respectively. Up to 10 min after cardiopulmonary bypass (CPB) and after correction for haemodilution, no observable effect of CPB on serum concentrations of Lp(a) could be demonstrated, whereas serum concentrations of total cholesterol and triglycerides showed a progressive and significant decline. Ten minutes after stopping CPB geometric means for cholesterol and triglyceride were 3.90 (0.82) and 0.90 (0.58) mmol/L, respectively. At the third post-operative day geometric Lp(a) and cholesterol means decreased to 62(90) mg/L and 2.97 (0.84) mmol/L, respectively, while triglycerides went up. It is concluded that Lp(a) levels remain constant during CPB, but mimic total cholesterol changes in the post-CABG period.

Adult↗
PubMed1997

A new pneumatic pump for extracorporeal circulation: TPP (true pulsatile pump). Experimental and first clinical results.

A pulsatile, membrane type pump, TPP, was developed for use in routine cardiac surgery. The artificial ventricle consists of a polycarbonate housing with an inlet and outlet polyurethane tricuspid valve. The membrane is actuated hydraulically. For pre-clinical studies, we designed a study in sheep. After a pump run of 6 hours the animals were allowed to recover and sacrificed after 72 hours. All clinical parameters returned to normal values (p > 0.05 vs. control values). During pump run we found elevated free plasma hemoglobine. However, these values returned to normal until the end of the observation period. Thereafter, the device was used in ten routine cardiac surgery procedures. All patients survived the procedure and were discharged from hospital. The postoperative course of lab parameters (kidney, liver and blood count) was no different to routine cardiac surgical procedures. This pulsatile pump system can thus be safely employed in cardiac surgery.

Aged↗
PubMed1991

[Comparison of new cardiac agents using differential therapeutic criteria].

Positive inotropism, reduction in preload, and reduction in afterload induced by any cardiacum are not exactly quantified in humans, nor are the patients classified as to their respective requirements. Also, any of these drug activities change with the patient's instantaneous cardiac and hemodynamic functional state. One reason for incomplete knowledge is a shortage of methods which allow to assess the inotropic state of the myocardium. In 17 patients, age range 56-76 years (two females, 15 male), undergoing routine coronary surgery, informed consent was obtained for implantation of a needle transducer for measurement of wall force. At the end of coronary surgery, developed myocardial force and aorto-coronary bypass flow were measured electromagnetically. After control measurements, 0.03, 0.06 and 0.1 mg/kg enoximone were injected slowly (3 min per dose) into the aorto-coronary bypass. Eight to 18 h after surgery, and again 18-48 h after surgery, the following measurements were made, first as a control, and then after 1.5 mg/kg enoximone i.v.: aortic pressure (AoP), central venous pressure (CVP) and pulmonary artery pressure (PAP), cardiac output (CO), and heart rate (HR). Peripheral vascular resistance (TPR) was calculated. Developed force and its derivatives were recorded continuously. Immediately after recovery from cardioplegia a 0.19 mg/kg dose of enoximone injected over 9 min into the aorto-coronary bypass induced an increase in bypass flow of 64 +/- 30%. Mean arterial pressure (MAP) showed a fall 5 min after enoximon injection on both occasions. The values were 73 (+/- 3.7) to 67 (+/- 2.6) mmHg, and 83 (+/- 3.1) to 78 (+/- 2.8) mmHg, respectively. The increase obtained in cardiac output (CO) 6.0 (+/- 0.4) to 7.4 (+/- 0.7) l.min-1, and 6.2 (+/- 0.7) to 8.5 (+/- 1.3) l.min-1 was significant at 5 min and remained so at 30 min on both occasions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

The use of midazolam versus propofol for short-term sedation following coronary artery bypass grafting.

Midazolam and propofol were compared in an open randomized study for postoperative sedation during 12 h of mechanical ventilation in 40 patients following coronary artery bypass grafting. After an intravenous loading dose of midazolam (50 micrograms.kg-1) or propofol (500 micrograms.kg-1), a titrated continuous infusion was administered of midazolam (mean dose 38.1 micrograms.kg-1.h-1 (SEM 2.6)) or propofol (mean dose 909 micrograms.kg-1.h-1 (SEM 100)) together with a narcotic analgesic infusion. During mechanical ventilation midazolam and propofol produced a similar quality of sedation, but recovery (midazolam 66 min (SEM 16); propofol 24 min (SEM 7)) and weaning from the ventilator (midazolam 243 min (SEM 44); propofol 154 min (SEM 33)) where faster with propofol. In the 2 groups administration of an intravenous loading dose caused a significant decrease in mean arterial pressure but hemodynamic tolerance during maintenance infusion was good.

Aged↗
PubMed1990

Autotransfusion during aorto-iliac surgery.

Red blood cell (RBC) quality and function during autotransfusion with the Solcotrans system were studied. Up to 64% (mean 999.5 +/- 310 ml) of the total volume of blood lost (mean 1895 +/- 707 ml) during operation in 10 patients undergoing elective abdominal aortic surgery was salvaged. No patient received homologous blood during surgery. Haemoglobin (Hb) and Haematocrit (PCV) values decreased but within acceptable limits. No evidence of DIC was found and renal function was unaffected. Mechanical and functional damage to the RBC was minimal and erythrocyte oxygen-carrying capacity was excellent. 2,3-DPGRBC concentration and RBC reduced glutathion were normal. The device was easy to handle and technical problems were not encountered. It was accurate in salvaging blood although the need for homologous blood was not entirely eliminated since four patients received homologous blood products in the postoperative period. No adverse clinical events occurred.

Aged↗
PubMed1990

Cardioprotective effects of carnitine in extensive aortocoronary bypass grafting: a double-blind, randomized, placebo-controlled clinical trial.

The cardioprotective effects of carnitine were tested in patients undergoing multiple aortocoronary bypass grafting. Intermittent aortic cross-clamping at 28 degrees C was used. Mean total cross-clamping time was 30 +/- 11 min. Patients were randomized into three groups: a control group receiving placebo (group 1), a group pretreated with 3 g carnitine intravenously before cardiopulmonary bypass (CPB) (group 2), and a group pretreated with 6 g carnitine intravenously (group 3). The markers of myocardial ischemia included levels of adenosine triphosphate, its catabolites, and creatine phosphate in transmural left ventricular biopsy specimens taken at the beginning and end of CPB, as well as hemodynamic recovery during weaning from CPB and for the next 24 h. The intravenous infusion of carnitine (3 or 6 g) had no hemodynamic effect. At the end of CPB myocardial tissue levels of adenosine triphosphate and creatine phosphate did not differ significantly among the groups (P greater than 0.05). Recovery of cardiac function during weaning from CPB and for the following 24 h was similar in all three groups (P greater than 0.05). It is concluded that pretreatment with carnitine neither facilitates weaning from cardiopulmonary bypass in patients undergoing aortocoronary bypass surgery nor favorably affects hemodynamic function during the next 24 h.

Aged↗
PubMed1987

The use of midazolam and diazepam for sedation following aorto-coronary bypass surgery.

The new water-soluble benzodiazepine midazolam was compared in a randomized study to diazepam for postoperative sedation in fifty patients following aortocoronary bypass surgery with a sufentanil-anesthesia. Midazolam and diazepam were administered intravenously in repeated doses in conjunction with an opioid infusion (piritramide) from the end of surgery during a twelve-hour study period, patients being artificially ventilated. Midazolam scored better than diazepam for quality of sedation and cardiovascular stability during the period of mechanical ventilation and for respiration during the weaning period and after extubation, although no difference was found in weaning time from artificial ventilation and time of extubation. Hemodynamic tolerance for both drugs was good. The administration of a loading dose of midazolam 5 mg caused a slight, transient decrease in mean arterial pressure. Midazolam appeared to be a more effective sedative agent than diazepam for short-term administration during mechanical ventilation. No evidence of cumulation and prolonged recovery was seen.

Adult↗
PubMed1983

Cardioprotective effects of lidoflazine in extensive aorta-coronary bypass grafting.

The cardioprotective effects of lidoflazine, a calcium entry blocker, were tested in patients undergoing multiple aorta-coronary bypass grafting (at least four grafts). Intermittent aortic cross-clamping at 25 degrees to 28 degrees C was used. Mean cross-clamp time was 11 minutes for one distal anastomosis. Patients were randomized into three groups: a control group (I), a group (II) pretreated with 0.5 mg . kg-1 lidoflazine intravenously before cardiopulmonary bypass (CPB), and a group (III) pretreated with 1 mg . kg-1 lidoflazine intravenously. The following markers of ischemia are used: (1) adenosine triphosphate (ATP), creatine phosphate (CP) and glycogen determined in transmural left ventricular biopsy specimens taken at the beginning and end of CPB; (2) ultrastructure in a similar pair of specimens; and (3) hemodynamic recovery 15 minutes after cessation of CPB. At the end of the intervention, ATP decreased to 73% in Group I but remained unchanged in Groups II (98%) and III (88%). CP decreased to 82% in Group I and remained unaltered in Groups II (100%) and III (110%). Glycogen decreased in Group I (to 44%) and in Group II (78%) but remained unchanged in Group II (138%). Ultrastructural study showed better preservation of the glycocalyx and sarcolemma in Group III than in Group I. Left ventricular stroke work index remained unaltered after CPB in Group III but decreased in Groups I and II to about 60% of its initial value. Thus lidoflazine pretreatment protects the myocardium in a dose-dependent manner against deterioration of myocardial function and structure.

Adenosine Triphosphate↗
PubMed1979

Total I.V. anesthesia using a continuous etomidate infusion.

Total I.V. anesthesia was given to 20 patients using an Etomidate continuous infusion to maintain sleep, combined to Fentanyl analgesia, Droperidol, Pancuronium for muscular relaxation and artificial ventilation with an oxygen-air mixture. All these patients were carefully observed during and for several hours after the anesthesia and the results noted. With the Fentanyl dosages used in this technique, peroperative analgesia was frequently insufficient. More Fentanyl would probably be needed with the inherent dangers of prolonged postoperative depression.

Adult↗
PubMed1978

Malignant hyperthermia.

Malignant hyperthermia is now recognized as a distinct entity in anesthetic practice and can be considered as a pharmacogenetic disease of obscure etiology occuring in man and pigs with a dominant inheritance. A close association with myopathy has been noted. Commonly used muscle relaxants or anesthetic drugs can act as triggering agents in genetically susceptible patients, who develop a real hypermetabolic state, characterized by a rapid rise in body temperature, muscular rigidity, tachycardia and tachypnoea, cyanosis and severe respiratory and metabolic acidosis, the lethality being about 60%. Other clinical, biochemical and histopathological features of this condition are described. The prevention and early diagnosis of this syndrome is very important. Therefore, it is necessary in the preanesthetic evaluation, to obtain information from the patient, with regard to previous anesthetic experiences, and to have a more exact anamnesis in patients with muscular diseases or with other members of the family under suspicion. Some screening methods are described. The prognosis of malignant hyperthermia depends on an early diagnosis. Although the incidence is, fortunately, small, this condition is sufficiently significant and acute in nature to require that anesthesiologist be aware of its clinical pathophysiology and prepared to recognize and treat it promptly. Therefore body temperature should be controlled continuously in all anesthetized patients, particularly in the younger age group and especially in those in which symptoms of muscle rigor have been observed particularly after application of succinylcholine and halothane. A regime of treatment is suggested, based on current concepts of the pathogenesis. It consists in establishing effective and rapid cooling, reversal of tissue hypoxia and correction of respiratory and metabolic acidosis and hyperkalemia. Specific therapy with dantrolene sodium may prove to be an answer to this serious problem.

Anesthetics↗