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Biomedical subjects

M Freysz

Publications and source records attributed to M Freysz.

At least 73 records · Page 4Linked to original sources
PubMed1990

[Technical constraints in rapid vascular fluid replacement].

Rapid fluid infusion remains the cornerstone for therapy of hypovolaemic shock. The principal limitations of flow rate are governed by the four variables of Poiseuille's law: tube internal diameter and length, viscosity of the fluid passing through the tube, and the pressure gradient between the two ends of the tube. Conventional transfusion systems, with wide bore tubing (up to 5.0 mm internal diameter), large bore cannulas (8.5 French introducer catheters), high pressure (up to 300 mmHg) and diluted blood, can result in a maximum flow rate of about 1,000 ml.min-1 (for crystalloid solutions). Specific apparatus for rapid infusion can increase this to 1,500 ml.min-1 (Rapid Infusion System, Haemonetics). Dry-heat warming devices and microfiltration, to remove microaggregates and prevent non haemolytic febrile transfusion reactions, seem necessary when carrying out rapid transfusions. However, the use of microaggregate filters could be avoided by the routine production of leukocyte-poor red blood cell concentrates.

Blood Transfusion↗
PubMed1990

Enhancement by hyponatremia and hyperkalemia of ventricular conduction and rhythm disorders caused by bupivacaine.

Intraventricular conduction disorders and reentrant arrhythmias in dogs can be produced by high plasma bupivacaine concentrations. The authors' aim was to determine if these conduction disturbances also occurred at moderate plasma bupivacaine concentrations (2.2-3.7 micrograms/ml) when in association with other factors which affect intracardiac conduction, such as hyponatremia and hyperkalemia. Thus, duration of the QRS complex, ventricular conduction time, and effective refractory period (ERP) was measured during ventricular pacing at 180 beats per min in 46 anesthetized, closed-chest dogs separated into five treatment groups as follows: group I, an iv bolus of 4 mg/kg of bupivacaine plus an infusion of 0.1 mg.kg-1.min-1 of bupivacaine followed in 50-60 min by 10 ml.kg-1.min-1 of 1.5% glycine iv to produce dilutional hyponatremia; group II, 1.5% glycine alone, as above; group III, bupivacaine, as above, followed in 50-60 min by 0.05 mmol.kg-1.min-1 of KCl iv to produce hyperkalemia; group IV, KCl alone, as above; and group V, bupivacaine, as above, except that the duration of infusion was 90 min. QRS duration and ventricular conduction time, which were prolonged approximately 33% and 61%, respectively, by bupivacaine alone were additionally prolonged 29% and 44%, respectively, when serum sodium concentration was lowered to 114 mmol/l and potassium concentration was raised to 7.7 mmol/l. The combinations of bupivacaine and hyponatremia, and bupivacaine and hyperkalemia tended to increase ERP more than did bupivacaine alone, although these changes were not statistically significant. Wave burst arrhythmias and episodes of ventricular tachycardia occurred spontaneously or were triggered by pacing in those dogs in which conduction time was most prolonged.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Ventricular and atrial electrophysiological effects of a IC antiarrhythmic drug, cibenzoline, in the innervated dog heart. Role of sodium and calcium channels.

The effects of cibenzoline, rightly known as a sodium channel inhibitor (class IC antiarrhythmic drug), were investigated in anaesthetized, closed-chest dogs, on conduction in the contractile fibres, ventricular and atrial, the His-Purkinje system and the atrioventricular node. In ventricular muscle, conduction time was measured between base and apex by two endocavitary electrodes. The other conduction times were obtained from the recording of the His bundle potentials. In addition, effective refractory period was determined by the extrastimulus method in ventricular and atrial muscle and in the atrioventricular node, and sinus rate monitored in the intervals of pacing periods. In the absence of vagal tone, cibenzoline in 4 mg.kg-1 dose prolonged conduction times in the ventricular contractile tissue, His-Purkinje system and atrial contractile tissue to a large extent, but decreasingly from the former to the latter. This prolongation was antagonized by hypernatremia (174 mmol.l-1). In contrast, conduction time in the atrioventricular node, effective refractory periods and sinus rate were very little influenced. In the presence of vagal tone, the prolongation of conduction times in the ventricular contractile tissue. His-Purkinje system and atrial contractile tissue did not differ substantially from previously. It was the same for ventricular effective refractory period. But atrial effective refractory period was then considerably lengthened, while conduction time and effective refractory period in the atrioventricular node were greatly shortened and sinus rate notably accelerated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Consequences of fluid absorption during transurethral resection of the prostate using distilled water or glycine 1.5 per cent.

This prospective and randomized study compared the consequences of two irrigating fluids, distilled water and glycine for transurethral prostatectomy. Forty-nine consecutive unselected patients undergoing transurethral resection of the prostate with spinal anaesthesia were investigated. The irrigating fluid was either distilled water (group A, 24 patients) or glycine 1.5 per cent (group B, 25 patients). The absorption of irrigating fluid was measured, all surgical events and any clinical signs of TURP syndrome during and after surgery were recorded. Early signs of TURP syndrome were observed in one patient in group A and in four in group B without further consequence. From all the biological variables, only plasma protein concentration, haematocrit, free plasma haemoglobin and free bilirubin concentrations were found to have changed. Plasma protein concentration and haematocrit decreased significantly during and after surgery in the two groups. Free plasma haemoglobin increased significantly with time: a significantly higher concentration was observed in group A than group B. Free bilirubin concentration increased with time in the two groups and was statistically greater in group A. With the two irrigating fluids, we observed a significant amount of haemolysis and haemodilution without clinical consequences. A low irrigating fluid pressure, a short resection time, and the use of spinal anaesthesia seems to us to be essential. Close observation of patients following transurethral prostatectomy is needed but the choice of the irrigating fluid does not seem to be important.

Absorption↗
PubMed1989

Are branched chain amino-acids beneficial for nutrition of severe surgical patients with sepsis?

UNLABELLED: This study investigated in severe sepsis the metabolic effects of two amino acid diets, including the same protein (0.3 gN/kg/day) and caloric intake (2g/kg/day glucose) but with different amino acid composition, 24% branched chain amino-acids (B.C.A.A.) for diet A (8 cases), 41% B.C.A.A. for diet B (11 cases). The two groups were obtained by randomisation at the operative day (D0) and were observed six days (D1-D6). During study, total nitrogen using a Kjeldhal method was measured. At D0 and D6, albumin, total hemolytic complement, transferrin, cholesterol, ammonaemia, insulin and amino acid pattern were studied in blood and skin tests were performed. The data were analysed by Mann-Whitney test. RESULTS: 1) The cumulative nitrogen balances of the six days are not significantly different, but at day 6 in diet B, patients started to be in an anabolic state (+3.7 gN) and in diet A catabolism persisted (-12 gN) (p<0.02). 2) Plasma B.C.A.A. are significantly higher and aromatic acids significantly lower in diet B. In order, Fischer ratio is also significantly different between the two regimens. All the other measured parameters are not significantly different. In this study, the B.C.A.A. enriched diet seems to be beneficial in surgical patients with severe sepsis.

Journal Article↗
PubMed1989

[Acute intracranial subdural hematoma of arterial origin after spinal anesthesia].

A case of an acute intracranial subdural haematoma occurring shortly after spinal anaesthesia is reported. A 67 year old poorly controlled hypertensive man, ASA II, underwent removal of a prostatic adenoma under spinal anaesthesia. He complained of postural headache on the third day after surgery. Unresponsive to the usual analgesics, his headache became severe, persistent and non postural on the fifth day. Twenty-four hours later, he suddenly presented with a left hemiplegia and became comatose. Computed axial tomography showed a large left-sided subdural haematoma, lying over the left hemisphere. During the immediate surgical removal, a pulsatile arterial bleeding originating from a small cortical artery was discovered, and stopped. The patient slowly recovered consciousness, but the hemiplegia remained. He finally died six months later of bronchopneumonia. The link between the haematoma and the spinal anaesthetic is not proven; the possible relationship between the two is discussed.

Aged↗
PubMed1989

Potentiation by mild hypothermia of ventricular conduction disturbances and reentrant arrhythmias induced by bupivacaine in dogs.

High concentrations of bupivacaine and profound hypothermia individually cause intraventricular conduction disturbances and reentrant arrhythmias. The effects of the combination of relatively low concentrations of bupivacaine and mild hypothermia are unknown and are the subject of this study. Three groups (n = 10-12) of dogs anesthetized with thiopental-chloralose were treated as follows: group 1, bupivacaine + hypothermia; group 2, bupivacaine alone; group 3, hypothermia alone. Bupivacaine was administered as a 4 mg/kg iv bolus followed by an iv infusion of 0.1 mg.kg-1.min-1. Hypothermia, i.e., a 4 degrees C reduction in core temperature, was produced by cooling the blood with an extracorporeal circuit. The peripheral ECG was recorded to determine the duration of QRS complexes and the QT interval. Conduction time and effective refractory period (ERP) of ventricular contractile tissue were measured with right ventricular endocavitary electrodes. Measurements were made with the heart paced at 180 beats/min and without pacing. In group 1 dogs, bupivacaine (plasma level, 2.8 +/- 0.3 microgram/ml) initially caused a prolongation of conduction time and QRS duration, which were further lengthened (approximately doubled) by a temperature decrease of 4 degrees C from baseline. The QT interval and ERP also were increased but to a lesser degree. In dogs in which the effects were most pronounced, rhythm disorders, such as wave burst arrhythmias (most common), premature systoles, ventricular tachycardia, and even ventricular fibrillation, occurred either spontaneously or during pacing. Bupivacaine alone (group 2) increased QRS duration and conduction time significantly, whereas hypothermia alone (Group 3) did not cause changes in any conduction variables. In neither group were dysrhythmias observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

[Systemic toxicity of local anesthetics. Pharmacokinetic and pharmacodynamic factors].

Local anaesthetics can have systemic adverse effects, mostly affecting the central nervous system and the heart. The physicochemical characteristics of the different local anaesthetics are recalled, for they determine the relationship between structure, activity and toxicity. The pharmacokinetic factors involved in the toxic effects of local anaesthetics, whether the drug is given in a single extravascular dose or, accidentally, within a blood vessel, are discussed. The toxic effects of repeated administrations of local anaesthetics depend on the metabolism of the drug as well as on pharmacokinetic factors. Possible maximal doses and drug interactions are also discussed. The mechanism of action of local anaesthetics, which block the sodium channel, explains their tissue toxicity and, more specifically, their central nervous and cardiovascular toxicities, which are more pronounced for the more potent local anaesthetic agents (bupivacaine, etidocaine). Systemic maternal effects and transplacental passage probably explain their foetal toxicity. Specific toxic effects are seen with some drugs, such as methaemoglobinaemia and allergic reactions (rarely for amide agents). Overall, local anaesthetic accidents are rare, but they must be prevented.

Anesthesia, Intravenous↗
PubMed1988

Haemodynamic effects of high plasma concentrations of bupivacaine in the dog.

The threshold concentrations responsible for circulatory collapse were experimentally investigated by intravenously infusing the drug at high rates (0.2 and 0.3 mg kg-1 min-1 over 20 min, and 0.4 mg kg-1 over 10 min) to 11 anaesthetized and ventilated dogs. Bupivacaine plasma concentrations at the time of haemodynamic measurements were, respectively, 4303 +/- 46, 5829 +/- 615, and 8930 +/- 689 ng ml-1 (means +/- SEM). Cardiac output appeared to be the first and the most affected of the haemodynamic variables studied. Its reduction was already significant with the 0.2 mg kg-1 min-1 bupivacaine infusion, whereas mean systolic blood pressure remained unchanged because of the compensatory increase in vascular resistance. The fall of cardiac output was enhanced by the rise in bupivacaine infusion rate, with simultaneous substantial decreases in left ventricular pressure and LV dP/dt max. At this stage, the increase in systemic vascular resistance was less marked than at low infusion rates, and was not sufficient to prevent hypotension. The variations of mean pulmonary blood pressure and pulmonary capillary wedge pressure did not reach statistical significance, and the absence of significant change in mean pulmonary blood pressure at the time cardiac output was reduced reflected the increase in pulmonary vascular resistance. These results suggest that high plasma concentrations of bupivacaine exert a depressant effect on cardiac contractions earlier than on arteriolar tone.

Animals↗
PubMed1987

Traumatic rupture of the pericardium with intermittent cardiac herniation in a multiple-trauma patient.

This is a case report of an 18-year-old multiply injured patient with blunt chest trauma, a total rupture of the right pericardium and an intermittent cardiac dislocation. Intermittent signs suggestive of cardiac tamponade accompanied the cardiac herniations. Acute renal failure followed these acute hemodynamic disorders. Early diagnosis and therapy were responsible for the successful outcome.

Adolescent↗