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F Sztark

Publications and source records attributed to F Sztark.

At least 37 records · Page 2Linked to original sources
PubMed1998

Comparison of the effects of bupivacaine and ropivacaine on heart cell mitochondrial bioenergetics.

BACKGROUND: High lipophilic local anesthetics interfere with mitochondrial energy metabolism. These metabolic effects could in part explain some of the toxic effects of local anesthetics, such as bupivacaine-induced myocardial depression. The aim of this study was to compare the bioenergetic effects of the local anesthetics bupivacaine and ropivacaine. METHODS: The effects of both local anesthetics on mitochondrial energy metabolism were studied in rat heart isolated mitochondria and in saponin-skinned left ventricle fibers. Oxygen consumption, adenosine triphosphate synthesis, and enzymatic activities of the complexes of the respiratory chain were measured. RESULTS: Bupivacaine and ropivacaine acted, in isolated mitochondria, as uncouplers between oxygen consumption and phosphorylation of adenosine diphosphate. Further, an inhibitory effect of mitochondrial respiration was evidenced with both anesthetics during maximal respiration and was assigned to a direct inhibition of complex I of the respiratory chain. Mitochondrial adenosine triphosphate synthesis was decreased by both mechanisms. However, both in isolated mitochondria and in permeabilized heart fibers, ropivacaine was less potent than bupivacaine. Adenosine triphosphate synthesis was completely suppressed at 3 mM (approximately 0.1%) bupivacaine, whereas 3 mM ropivacaine induced only about a 40% inhibition. CONCLUSIONS: Ropivacaine disturbs mitochondrial energy metabolism less than bupivacaine does. The lower lipid solubility of ropivacaine may be responsible for the lesser dose-dependent effects of this drug on mitochondrial bioenergetics.

Amides↗
PubMed1997

[Hemodynamic effects of hypertonic saline solutions].

Haemodynamic effects of hypertonic saline solutions (HSS) have been extensively studied in animals and humans. Hypertonic sodium chloride (7.5%, 2,500 mOsm.L-1) either alone or combined with colloids, remains the standard solution. The haemodynamic response of HSS observed during treatment of hypovolaemic shock is explained by 1) an increase in preload due to the expansion of the plasma volume and a musculocutaneous vasoconstriction and 2) a decrease in systemic vascular resistance and afterload. A myocardial stimulation has been shown in various experimental conditions and in humans. However, the clinical relevance of this inotropic effect is questionable. Haemorrhagic shock is the main indication for small volume resuscitation with HSS. Other potential situations for the use of HSS are volume replacement in perioperative period, septic shock or burn injury and cardiopulmonary resuscitation. Before recommending the clinical use of HSS, additional clinical studies are required to substantiate the benefits of HSS over colloids.

Burns↗
PubMed1997

Effects of the local anesthetic bupivacaine on mitochondrial energy metabolism: change from uncoupling to decoupling depending on the respiration state.

The local anesthetic bupivacaine has been found to uncouple oxidative phosphorylation. However, the precise mechanisms of bupivacaine uncoupling have not been elucidated. In the present paper, we demonstrate that the uncoupling effect of the local anesthetic depends on the respiration state. In state 4-respiration (no ADP phosphorylation), bupivacaine acts as a true protonophoretic uncoupler. On the other hand, in state 3-respiration (ADP phosphorylation), bupivacaine induces a change in proton pump stoichiometry and appears to be a decoupler (slip inducer). Moreover, at high concentration, the local anesthetic inhibits the respiratory chain itself. Thus, the divergent reports in the literature on the action of bupivacaine show in fact the various mechanisms by which the local anesthetic may alter mitochondrial energy metabolism.

Adenosine Diphosphate↗
PubMed1997

The use of 0.25% lidocaine with fentanyl and pancuronium for intravenous regional anesthesia.

The present study was designed to assess the efficacy of fentanyl and pancuronium combined with dilute lidocaine solution for intravenous regional anesthesia of the arm. Forty adult patients undergoing upper limb surgery were randomly allocated to receive either 0.6 mL/kg of 0.5% lidocaine (3 mg/kg) or 0.6 mL/kg of 0.25% lidocaine (1.5 mg/kg) with 1 microg/kg of fentanyl and 0.5 mg of pancuronium. The onset of sensory and motor blocks was significantly shorter in the 0.5% lidocaine group (P < 0.05). However, no differences in analgesia or motor blockade were found between the two groups at 20 min tourniquet time. Regional anesthesia was considered successful in more than 85% of patients. One patient in the 0.25% lidocaine group experienced a transient diplopia after tourniquet release. Postoperative analgesia time was similar in the two groups. We conclude that the addition of fentanyl plus pancuronium to the lidocaine solution reduces the dose of the local anesthetic and possibly systemic toxicity.

Adult↗
PubMed1996

[Indications and role of albumin for vascular loading in trauma patients and during preoperative period].

The use of albumin solutions for volume replacement remains controversial. The last American guidelines recommend the use of albumin for resuscitation in case of a contra-indication of artificial colloids or the requirement of sodium restriction. Recent trials did not show any beneficial effect of albumin on the mortality and morbidity rates. Only an improvement of the rheologic conditions has been found with albumin (and dextran 40), in comparison with starch and gelatin. On the basis of cost-effectiveness considerations, artificial colloids should be at this time favoured over albumin for intravascular expansion, except in pregnant women. For resuscitation, albumin could be used when the recommended upper limit of hydroxyethyl starch vol-ume has been reached and fresh frozen plasma not yet required. During preoperative haemodilution, low molecular weight hydroxyethyl starch has at least the same efficacy as albumin. When a rheological effect is required, albumin could be used.

Albumins↗
PubMed1996

[Subarachnoid hemorrhage caused by aneurysm rupture. Initial management of patients].

Subarachnoid haemorrhage is a severe illness with a high mortality and morbidity. Its diagnosis is considered in the case of a brutal, violent and unusual headache. It is confirmed rapidly with the conventional techniques such as CT-scan and lumbar puncture. The main complications (ischaemia, rebleeding, hydrocephalus) occur during the first two weeks and are a usual event in case of a lack of diagnosis or specialised medical, surgical and radiological management. Among the complications, rebleeding badly affects prognosis, and only early surgery or interventional radiology may improve the outcome. Delayed ischaemia may be prevented by medical management with correction of hypovolaemia and administration of calcium antagonists, before and after surgery, particularly between the 4th and the 10th day. When signs of ischaemia occur, aggressive treatment should be administered in order to improve cerebral perfusion pressure and cerebral blood flow. The treatment is aimed to prevent the complications of subarachnoid haemorrhage and to establish optimal conditions for surgical and radiological procedures.

Aneurysm, Ruptured↗
PubMed1996

Hemodynamic effects of spinal anesthesia in the elderly: single dose versus titration through a catheter.

Sixty elderly patients (> 70 yr old) undergoing surgery for hip fracture were prospectively studied in order to compare hemodynamic tolerance of titrated doses of hyperbaric bupivacaine using continuous spinal anesthesia (CSA) versus single-dose spinal anesthesia (SDSA). Patients were randomized into two groups (CSA group: n = 30; SDSA group: n = 30). The SDSA patients received 10-15 mg of 0.5% hyperbaric bupivacaine (based on age and height), and the CSA patients received a starting dose of 5 mg of 0.5% hyperbaric bupivacaine, followed after 15 min by optional reinjection of 2.5 mg every 5 min until a T10 level sensory block was reached. Onset of anesthesia, noninvasive hemodynamic variables and the need for ephedrine were studied for 4 h after induction of anesthesia. Spinal anesthesia was successful in all patients. Decreases in mean arterial pressure were significantly less frequent and less pronounced in the CSA group (19.9% +/- 1.6% of the baseline value) than in the SDSA group (40.2% +/- 1.9%, P < 0.0001). The mean dose of ephedrine was significantly less in the CSA group (1.8 +/- 0.7 mg, administered to only 37% of patients) than in the SDSA group (19.4 +/- 3.3 mg administered to all patients, P < 0.0001). No late complications related to the spinal anesthesia technique were observed in either group. We concluded that CSA, using small titrated doses of 0.5% hyperbaric bupivacaine, is safe, efficient, and provides better hemodynamic stability than SDSA in elderly patients.

Aged↗
PubMed1995

Effects of the anaesthetic propofol on the calcium-induced permeability transition of rat heart mitochondria: direct pore inhibition and shift of the gating potential.

Mitochondrial calcium exchanges are involved in intracellular calcium homeostasis and in the contraction-relaxation process in myocytes. The calcium-induced permeability transition of the heart mitochondria inner membrane appears to be an important calcium efflux mechanism involved in some physiological and pathological situations. The negative inotropic effect of the anaesthetic propofol results in part from a decrease in intracellular calcium availability. Thus, this study evaluates the effects of propofol on calcium transport and permeability transition of heart mitochondria. The propofol-inhibition of the permeability transition of liver mitochondria was previously investigated [Eriksson, O. (1991) FEBS Lett. 279, 45-48] in such conditions that its uncoupling effect was not taken into account. We show here that propofol uncoupling results in a decrease in calcium uptake rate which could in part explain the decreased permeability transition rate. However, comparison of equipotent uncoupling concentrations of propofol and carbonylcyanide m-chlorophenylhydrazone reveals that beyond this uncoupling effect, propofol has a direct inhibitory action on the permeability transition pore, concomittant with a shift of its gating potential.

Animals↗
PubMed1995

[Traumatic diaphragmatic rupture with delayed unusual disclosure].

The authors report the case of a delayed presentation of a traumatic diaphragmatic rupture in a 22-year-old patient admitted to hospital for a minor surgical procedure under general anaesthesia. Nine months before, he had a road traffic accident with a minor thoracic trauma. Three days after surgery, the patient was readmitted for a tension hydrothorax due to the herniation and the perforation of the stomach into the left pleural cavity. Such a delayed presentation of a traumatic diaphragmatic rupture remains uncommon. The peroperative ventilatory factors involved in the development of the hernia are discussed.

Accidents, Traffic↗
PubMed1995

[Bilateral bronchial rupture: problems of respiratory management].

The authors report the case of bilateral bronchial rupture in a 39-year-old multiple trauma patient. During the thoracotomy for right main bronchus repair, a partial left bronchial rupture was recognized because of severe hypoxaemia after left selective intubation.

Adult↗
PubMed1994

[Autotransfusion, with blood drained from a hemothorax, using the ConstaVac device].

The technique of autotransfusion with blood drained from a haemothorax has been described nearly 80 years ago. The shed blood is easy to collect and is incoagulable. This technique as two indications: lifesaving autotransfusion in the prehospital phase and blood saving and/or transfusional safety at hospital arrival. This prospective study assessed its value as well as the advantages and disadvantages of the ConstaVac system in 30 patients suffering from haemothorax. This apparatus consists of a 800 mL collecting reservoir on a support equipped with an electric aspirator and a battery. The collected blood is transferred into a reinfusion bag while remaining in a closed circuit. The retransfused volume was 685 +/- 430 mL, representing 80% of the collected volume. The retransfusion took place in less than four hours. The patients with an isolated haemothorax did not receive any homologous blood. Only one technical problem occurred, related to the excessive volume of the haemothorax. The shed blood has decreased content of platelets, fibrinogen, and is incoagulable. Moreover, it is hemolyzed. Its hematocrit is lower than the patient's one. On the other hand, the concentration of 2,3 DPG remains normal. These modifications have no detrimental consequences on the patients as long as the autotransfused volume does not exceed two litres. Infectious problems are rare. Handling requires strict asepsis. The ConstaVac system is marketed for postoperative autotransfusion. It is compact, self-contained and very easy to use. It is the only system able of ensuring blood drainage and retransfusion simultaneously, without requiring any opening of the circuit.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Effects of bupivacaine on cellular oxygen consumption and adenine nucleotide metabolism.

Previous studies on isolated mitochondria have shown an alteration of mitochondrial metabolism by local anesthetics, with an inhibition of adenosine triphosphate synthesis. To show that the same is true for mitochondria intracellularly the effects of the local anesthetic bupivacaine on cellular energy metabolism were studied on cultured fibroblasts. Cells in suspension were analyzed for oxygen consumption using a polarographic method with a Clark electrode, and for cytosol and mitochondrial adenine nucleotides by high performance liquid chromatography. Bupivacaine produced a dose-dependent inhibition of oxygen consumption (50% inhibition at 1.5 mM). After incubation in the presence of bupivacaine, adenosine triphosphate and total adenine nucleotides decreased in the cells, as did the adenylate energy charge. These results demonstrate that bupivacaine interacts with cellular energy metabolism and leads to a depletion of high-energy phosphates. Such intracellular mechanisms could explain in part bupivacaine-induced myocardial depression.

3T3 Cells↗