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Biomedical subjects

C Saint-Maurice

Publications and source records attributed to C Saint-Maurice.

At least 73 records · Page 4Linked to original sources
PubMed1988

Respiratory effects of nitrous oxide during halothane or enflurane anaesthesia in children.

The respiratory effects of nitrous oxide (N2O) were studied during halothane and enflurane anaesthesia in 12 children (mean age 46.4 +/- 29.3 months, mean weight 15.3 +/- 4.2 kg) during surgery under continuous extradural anaesthesia. Four equipotent anaesthetic states were studied in random order: 1) halothane 1 MAC in oxygen, 2) halothane 0.5 MAC + 50% N2O, 3) enflurane 1 MAC in oxygen, 4) enflurane 0.5 MAC +50% N2O. End-tidal fractions of CO2 (PetCO2) and halothane and enflurane were measured using infrared analysers. The respiratory variables (tidal volume VT, minute ventilation VE, respiratory frequency F, inspiratory time Ti, mean inspiratory flow VI, effective inspiratory time Ti/Ttot) were measured using a pneumotachograph. Significant changes were observed between the four states for VE, VI, F and PetCO2, whereas the values of VT, Ti and Ti/Tot did not differ significantly. The respiratory depressant effect of 1 MAC of either halothane alone or of the mixture of halothane and N2O was very similar. During enflurane anaesthesia, PetCO2 was less increased when N2O was substituted for enflurane, owing to a significant increase in respiratory frequency. A marked decrease in VE together with an increase in PetCO2 was observed during enflurane anaesthesia (states 3 and 4) when compared to the corresponding states during halothane anaesthesia (states 1 and 2). The respiratory depressant effect of enflurane is greater than that of halothane in unpremedicated children, even when substituting N2O for an equal MAC fraction of enflurane.2+ The effect of N2O on respiratory patterns seems to depend on the inhalational agent used and/or on the vesting respiratory frequency.

Anesthesia, Inhalation↗
PubMed1988

[Autotransfusion using Cell Saver III. Experience with 90 cases of surgery of the spine in childhood and adolescence].

Intra-operative transfusion was used with Cell Saver Haemonetics III in 90 children undergoing spinal surgery for scoliosis. This technic keeps pace with controlled bleeding by collecting and processing shed blood and reinfusing washed packed red cells. During high blood loss procedures this device allowed to save up 51% of shed red cells. Our study of the intra-operative bleeding and its replacement was assessed with calculation using an individual regression line for each patient. Statistical analysis was performed by using multivariate correlation and "step wise analysis".

Adolescent↗
PubMed1988

Bupivacaine pharmacokinetics during epidural anaesthesia in children.

Blood concentrations and pharmacokinetic parameters of bupivacaine were measured after epidural injection in children aged from 1 to 7 years. The children were allocated to two groups. In Group 1 (five children), pharmacokinetic parameters were measured after a single bolus injection of bupivacaine 0.25% with adrenaline 1:200,000. In Group 2 (eight children), pharmacokinetic parameters were measured after the initial injection and the second injection. The same local anaesthetic was used. The volume of the second injection was half of the initial volume. In children of Group 1, maximum mean concentration (CPmax) was 0.64 +/- 0.05 microgram ml-1, time to maximum concentration (Tmax) 19.2 +/- 3.9 min, vascular absorption (T1/2 abs) 4.3 +/- 1.5 min, terminal half-life (T1/2 beta) 227 +/- 37.7 min, volume of distribution (Vd) 3.4 +/- 0.51 kg-1, and total body clearance (Clt) 11.0 +/- 2.0 ml min-1 kg-1. When compared to an adult's pharmacokinetic parameters, both Vd and Clt were increased, so that T1/2 beta remained essentially unchanged. In children of Group 2, the first repeat injection was performed at 110 +/- 6.9 min. Mean CPmax increased significantly (20% after the second injection), whereas the values of the pharmacokinetic parameters measured did not differ significantly from those measured in children in Group 1. The results obtained in the present study demonstrate that the pharmacokinetic parameters of bupivacaine in children do not differ markedly from those reported in adults and that in the recommended dosage, the mean maximum concentrations, even after the second injection, are less than the presumed toxic levels.

Anesthesia, Epidural↗
PubMed1987

Continuous extradural anaesthesia in children. Clinical and haemodynamic implications.

This study reports the experience of a department of paediatric anaesthesia with 234 continuous extradural anaesthetics performed in 229 children over a 15-month period. Fifty-nine of the children were aged 0-2 yr, 71 were aged 2-8 yr and 104 were older than 8 yr. The surgical procedures lasted more than 60 min (mean 150 +/- 10.6 min); all were carried out under light general anaesthesia. Technical procedure and difficulties are reported. The only local anaesthetic agent used was bupivacaine with or without adrenaline. Mean initial dosage was 0.75 ml kg-1 for children weighing less than 20 kg and 1 ml/10 cm of height for children taller than 100 cm. Using 0.25% bupivacaine mean times until a further injection were 92.0 +/- 2.0 min for bupivacaine with adrenaline and 71.0 +/- 2.5 min for bupivacaine without adrenaline (P less than 0.001). A much longer duration of analgesia was found for younger children using the solution with adrenaline. A haemodynamic study was performed in 74 unpremedicated children (ASA I; aged 0-2 yr (n = 15), 2-8 yr (n = 26) and older than 8 yr (n = 35). Before induction of anaesthesia, heart rate (HR) was significantly increased in the youngest children, but no significant change was found for systolic arterial pressure (SAP). After extradural anaesthesia with 0.25% bupivacaine with adrenaline 1:200000, minimal changes in HR or SAP occurred in children younger than 8 yr; in those older than 8 yr a significant decrease in both HR and SAP was observed. Changes in SAP were at their maximum 25 min after the extradural block and changes in HR were not statistically significant before the 25th min following injection of local anaesthetic. The catheter remained in place in 155 children for postoperative analgesia, mainly for the first 48 h.

Adolescent↗
PubMed1987

A comparison of alfentanil pharmacokinetics in children and adults.

The pharmacokinetics of alfentanil have been studied in eight children aged between 4 and 8 yr and five adults during general anesthesia. All patients were given 20 micrograms/kg alfentanil as an intravenous bolus injection. Plasma concentrations were measured at intervals up to 6 h by radioimmunoassay. Plasma protein binding was measured by equilibrium dialysis using tritiated alfentanil. The optimal pharmacokinetic model for alfentanil was an open two-compartment model. Total apparent volume of distribution (Vdss) was 457 +/- 160 ml/kg in adults and 163 +/- 110 ml/kg in children (P less than 0.01). When recalculated by surface area Vdss was still decreased in children (P less than 0.01). Plasma clearance (Cl) was similar in the two groups. Terminal elimination half-life was significantly shorter in children (40 +/- 9 min) than in adults (97 +/- 22 min; P less than 0.01). The shorter elimination half-life could be due to the smaller total apparent volume of distribution in children. Plasma protein binding was comparable between children and adults and could not explain the smaller volume of distribution in children. It is suggested that the smaller volume of distribution of alfentanil in children is a result of the decreased percentage of fat tissue in children.

Adult↗
PubMed1987

The respiratory effects of isoflurane, enflurane and halothane in spontaneously breathing children.

The respiratory effects of halothane, isoflurane and enflurane were assessed during nitrous oxide anaesthesia (N2O 50%) in three groups of unstimulated, spontaneously breathing children who weighed 10-20 kg and were aged 1-6 years. Respiratory variables were measured or calculated from capnographic and pneumotachographic recordings at three multiples of minimal alveolar concentration (MAC). The slope of the carbon dioxide response was measured. Similar increases in end tidal carbon dioxide were found for the three agents at each MAC multiple, and similar decreases in tidal volume and in the slope of the ventilatory response to carbon dioxide. A dose-related tachypnoea occurred with halothane and a significant decrease in the duration of inspiration and the duration of each breath at the deepest level of anaesthesia. A significant increase in both these times occurred with enflurane, and a decrease in respiratory rate. No change in respiratory rate occurred with isoflurane at increasing alveolar concentrations whereas at each level of anaesthesia inspiratory time was significantly reduced.

Anesthesia, Inhalation↗
PubMed1987

[Better acceptance of measures for induction of anesthesia after rectal premedication with midazolam in children. Comparison of results of an open and placebo-controlled study].

The rectal administration of midazolam for premedication of children before induction of anesthesia by mask was investigated in two clinical studies. In 62 children aged between 2 and 10 years, midazolam was given by open design at various dosages (0.15 mg.kg-1, 0.25 mg.kg-1, 0.30 mg.kg-1, 0.35 mg.kg-1, 0.40 mg.kg-1) to evaluate the most effective dose for optimal acceptance of the mask and gas mixture. An additional 40 children between 3 and 9 years received 0.2 mg midazolam.kg-1 body weight or placebo in a double-blind design to estimate the lower limit of efficacy of midazolam. All children were classified as ASA I and had to undergo a surgical procedure. Within the two studies the children were not different with respect to their general data, age, weight, and sex. In both studies more boys than girls were included. Parameters of efficacy were the degree of sedation before and at 10, 20, and 30 min after midazolam as well as acceptance of the mask and the gas mixture at induction of anesthesia. In all groups, including placebo, a sedative and tranquilizing effect of the premedication was found. The rectal administration of 0.35-0.4 mg midazolam.kg-1 is most suitable for the preoperative medication of children between 2 and 10 years. Due to the degree of sedation and the relief of anxiety toward the surroundings and the operation, the induction of anesthesia is optimally accepted by the child. In contrast, the effect of a dose around 0.2 mg midazolam.kg-1 body weight is not much different from that of placebo and is not sufficient for effective premedication.

Administration, Rectal↗
PubMed1987

Continuous epidural anaesthesia for major abdominal surgery in young children.

The benefits of epidural anaesthesia combined with general anaesthesia were studied in young children scheduled for major abdominal surgical procedure (pull-through for Hirschsprung's disease). Two groups of nine children were studied receiving, respectively, general anaesthesia or general anaesthesia plus epidural anaesthesia. In the group receiving both general and regional anaesthesia, a polyurethane 24 G catheter was inserted via a Tuohy needle 19 G into the lumbar epidural space after induction of anaesthesia and intubation and bupivacaine, 0.25%, was injected epidurally (mean initial volume 0.71 +/- 0.04 ml kg-1). No opiates were needed during operation on the children in this group. After epidural anaesthesia, heart rate decreased significantly but systolic blood pressure remained unchanged. During surgery mean values of both heart rate and systolic blood pressure were significantly lower in the regional analgesia group compared to the general anaesthesia group. The need for blood replacement was also significantly lower, whereas pre- and post-operative haematocrit values were not significantly different. Administration of fluid and electrolytes during operation was also similar in both groups. A combination of epidural and general anaesthesia avoids the use of opiates during surgery, provides excellent per- and post-operative analgesia, allows a rapid and safe recovery, and facilitates the nursing of young children.

Anesthesia, Conduction↗
PubMed1987

[Pharmacokinetics of propofol as an induction agents in adults].

The disposition kinetics of Propofol have been determined in 7 patients (3 men, 4 women) receiving 2.5 mg/kg for induction of anaesthesia. Peripheral venous samples were collected up to 12 hours after injection of the drug. Data analysis indicates a 3 compartment model with a terminal half-life of 480 +/- 141 min, clearance of 0.0352 +/- 0.0014 l/min/kg and volume of distribution of 24.2 +/- 6.2 l/kg.

Anesthetics↗
PubMed1986

[Percutaneous or surgical central catheters in the newborn infant].

Central microcatheters are important in neonatal intestinal surgery, as peripheral veins are quickly all used up in these patients; they are essential in maintaining a satisfactory nutritional status during the period of digestive exclusion. This retrospective study over an 18 month period concerned 105 catheters (82 central percutaneous catheters and 23 surgical catheters) put up in neonates operated on within the first few days of life. The advantages and disadvantages of both methods of catheterization were assessed by means of the infectious or mechanical complications, as well as the length of time the catheters were used. The frequency, timing and type of mechanical incidents requiring removal of the catheter were the same for both groups. There was only one septic accident, and this with a surgical catheter. An analysis of the patient files helped to decide on the best route for use in central catheterization, as well as technical improvements. Because of the absence of infectious accidents in the percutaneous series, this method was preferred, especially as it has a certain number of advantages over the surgical method. Percutaneous central microcatheterization would appear well suited to medium term parenteral feeding.

Catheterization↗
PubMed1986

Clinical pharmacology of vecuronium in children. Studies during nitrous oxide and halothane in oxygen anaesthesia.

Forty-seven children (ASA I or II) were studied during nitrous oxide-oxygen, halothane anaesthesia. The dose-response curve for vecuronium was determined after the injection of a single bolus (40, 55 or 70 micrograms kg-1) to 33 patients. The ED50 and ED95 were 31 and 64 micrograms kg-1 respectively. Fourteen children received a larger dose (100 micrograms kg-1); good intubating conditions were obtained in all of these within 2 min. After a single bolus (100 micrograms kg-1) the duration of action was 36.5 min and the recovery index was 9.3 min. In patients who received small maintenance doses (25 micrograms kg-1) after a single bolus (100 micrograms kg-1) the recovery index after the last maintenance dose was not increased. There were no significant changes in heart rate or arterial pressure. In children, vecuronium has a short duration of action and lacks cumulative or cardiovascular side affects.

Anesthesia, Inhalation↗
PubMed1986

Pharmacokinetics and pharmacodynamics of vecuronium and pancuronium in anesthetized children.

The pharmacokinetics and pharmacodynamics of vecuronium and pancuronium were determined in 12 children (3-6 yr) undergoing minor surgery under 60% nitrous oxide, 1 MAC halothane anesthesia. When the level of anesthesia and the electromyograph (EMG) recording of the adductor pollicis were stable, an intravenous bolus of vecuronium (100 micrograms/kg) or pancuronium (100 micrograms/kg) was administered. Plasma concentrations of the two muscle relaxants were determined for 6 hr after the administration by means of a fluorimetric assay followed by a thin layer chromatography. Plasma concentrations of vecuronium and pancuronium declined biexponentially in children and no metabolites could be detected in plasma. The elimination half-lives of vecuronium and pancuronium did not differ significantly. The volume of distribution at steady state (Vdss) was greater (P less than 0.05) after vecuronium (320 +/- 181 ml/kg; mean +/- SD) than after pancuronium (203 +/- 36 ml/kg). Plasma clearance of vecuronium (2.8 +/- 0.9 ml X min-1 X kg-1) was greater than that of pancuronium (1.7 +/- 0.2 ml X min-1 X kg-1; P less than 0.05). Plasma concentrations measured at 10%, 50%, or 90% recovery of the EMG response did not differ significantly for vecuronium and pancuronium. Thus the shorter duration of action of vecuronium is probably due to its greater apparent volume of distribution, as well as to its higher plasma clearance. Thus although the elimination half-lives are comparable, the plasma disappearance of vecuronium is more rapid than that of pancuronium.

Anesthesia, General↗