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R Desprats

Publications and source records attributed to R Desprats.

11 recordsLinked to original sources
PubMed1997

Influence of maternal blood flow on the placental transfer of three opioids--fentanyl, alfentanil, sufentanil.

The placental transfer of three opioids used in peridural analgesia, fentanyl, alfentanil and sufentanil, and two reference substances, antipyrine and *H2O, was determined ex vivo in the human placental cotyledon system. (1) In the first set of experiments, the infusion rates were constant and fixed at physiological flow rates. Under these conditions, the magnitude of the materno-fetal transfer was in the following order: *H2O = antipyrine = fentanyl > alfentanil > sufentanil. No particular influence of molecular weight, lipophilia, pKa or the degree of ionization could be discerned. (2) In the second set of experiments, the influence of different flow rates, reflecting various pathophysiological conditions, was examined. There was a linear relationship between the maternal flow and the materno-fetal transfer of the three opioids. On the other hand, for antipyrine and tritiated water, the relationship was logarithmic, a difference attributed to the marked lipophilia of the opioids. (3) At high maternal flow rates, saturation was observed for all five substances due to the short duration of contact with the membrane. There were logarithmic relationships between the maternal flow and the materno-fetal transfer. (4) These findings emphasize the importance of the lipophilic and hydrophilic characteristics of drugs on placental transfer, especially in the event of fluctuations in maternal flow.

Alfentanil↗
PubMed1993

Evaluation of six markers of haemostatic system in normal pregnancy and pregnancy complicated by hypertension or pre-eclampsia.

OBJECTIVE: To establish the plasma evolution of prothrombin fragments 1+2 (F 1+2), thrombin-antithrombin III complexes (TAT), fibrin fragment D-Dimers (DD), von Willebrand factor antigen (vWf), Type 1 plasminogen activator inhibitor antigen (PAI) and blood platelet count during normal pregnancy and to compare these values with those obtained in hypertensive or pre-eclamptic pregnancies. DESIGN: Cross-sectional study. SUBJECTS: Forty-seven healthy pregnant women with gestational age ranging between 5 and 40 weeks, and fourteen women with gestational age ranging between 25 and 38 weeks presenting with either gestational hypertension (n = 4) or pre-eclampsia (n = 10). Numbers of nulliparous women in the control, hypertension and pre-eclampsia groups were 13/47 (28%), 1/4 (25%) and 9/10 (90%), respectively. RESULTS: All six markers increased with gestational age in normal pregnant women (P < 0.01). Using the upper limit of 95% prediction interval obtained from regression curves as normality threshold, TAT showed the best sensitivity (71% vs < 30% for F1+2, DD, vWf, PAI and platelet count). CONCLUSION: TAT appears to be an interesting marker for detecting haemostatic system alterations in pregnancies complicated by hypertension or pre-eclampsia. A large prospective study to determine its clinical usefulness for such complicated pregnancies is currently in progress.

Adult↗
PubMed1991

Maternal and umbilical cord concentrations of fentanyl after epidural analgesia for cesarean section.

The maternal and umbilical concentrations of fentanyl were measured after epidural analgesia for cesarean section, using a highly sensitive radioimmunoassay method. Sixteen parturients were anesthetized with a single epidural injection of a mixture of 85 mg bupivacaine 0.5%, 60 mg etidocaine 1%, and 100 micrograms fentanyl with epinephrine 1:200,000. Apparent maternal individual maximum peak concentration (Cmax) of fentanyl was 0.38 +/- 0.16 ng/ml (mean +/- SD) (range 0.12-0.59 ng/ml) and the time to reach Cmax (Tmax) was 24 +/- 14 min (range 5-60 min). Infants were born 19 to 42 min after epidural administration of fentanyl (mean 27 min). Fentanyl concentrations in neonates was 0.13 +/- 0.04 ng/ml for the umbilical vein and 0.06 +/- 0.03 ng/ml for the artery. The fetus extraction ratio was 53 +/- 19% (range 20-83%). The large difference between arterial and venous concentrations of fentanyl may be due to a metabolization by the fetus and/or an uptake of the drug in the fetal tissues. Thus, even if fentanyl levels reaching the fetus after cesarean section under epidural anesthesia, using local anesthetics with 100 micrograms of fentanyl, are within safe range values, the likelihood of fentanyl uptake by fetal tissues calls for a cautious use of repeated fentanyl administration.

Analgesia, Epidural↗
PubMed1990

Effects of pH on antipyrine transfer across the human placenta ex vivo.

The influence of pH variations on transplacental transfer of antipyrine was studied using a human placental cotyledon perfused ex vivo. The antipyrine transfer rate is positively correlated with the pH in the fetal circulation and negatively correlated with the pH in the maternal circulation. Thus, the transfer rate is negatively correlated with the difference between pH values in maternal and fetal circulations. The antipyrine transfer rate is also positively correlated with the flows in maternal and fetal circulations. The above parameters allowed to explain 50% of the variance on the transfer rates obtained in various experimental conditions. In a final series of experiments where these parameters for each placenta were fixed at identical values, a good reproducibility in the results was obtained, the variation coefficient being 17%. Thus, establishing the effect of variations in pH allowed a good standardization of the perfused cotyledon model. This effect cannot be explained by modifications in the ionized fraction of the antipyrine molecular and is probably due to physiological mechanisms.

Adult↗
PubMed1983

[Peridural analgesia during labor: comparative study of a fentanyl-marcaine combination and marcaine alone].

A randomised trial was carried out to evaluate the use of a mixture of fentanyl with marcaine in epidural analgesia. Two series of 30 patients each were studied: in the first only marcaine was given for the epidural and in the second marcaine and fentanyl mixed. Stronger and longer analgesia was obtained in the series where fentanyl was added showing that local anaesthetics can be potentiated by opiates. There was no significant difference in the two series as far as the cardiovascular, respiratory and blood gas measurements were concerned, either in the mother or in the fetus.

Anesthesia, Epidural↗
PubMed1977

[Tracheo-bronchial intubation for surgery of the esophagus via a thoracic approach].

Tracheo-bronchial intubation using a double-lumen Carlens tube provides the surgeon with a mediastinal operating field free of any obstruction by the lung and provides greater surgical ease than that of an assistant retracting a constantly invasive lung with tracheal intubation. This anaesthetic technique involving the ventilation of only one lung during the endothoracic period of the surgical procedure has not been used routinely for extra-pulmonary surgery since the shunt which is created leads to a fear of dangerous hypoxia. The aim of this study involving 30 patients is to demonstrate that the blood oxygen saturation obtained by the careful ventilation of a single lung, that of the side on which the patient is lying, is perfectly acceptable and comparable with the preoperative oxygen saturation of the subject at rest. This is obtained at the price of an increase in insufflation pressures of the order of 100 percent. Re-expansion of the collapsed lung without visual confirmation after careful endobronchial aspiration makes it possible to prevent the development of areas of micro-atelectasia and to ensure the absence of any pulmonary postoperative complications.

Adult↗