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Biomedical subjects

D G Gaylard

Publications and source records attributed to D G Gaylard.

11 recordsLinked to original sources
PubMed1993

Factors affecting the maternal-fetal distribution of pethidine and bupivacaine in the rabbit.

Twenty pregnant New Zealand white rabbits (mean body weight 4.6 kg) within 3 days of term were anaesthetized and given an intravenous infusion of bupivacaine 1.25 mg/ml with pethidine 1.25 mg/ml at a rate of 12 ml/h for 20 min, 6 ml/h for 60 min and 3 ml/h thereafter. In 10 of the does the solution also contained adrenaline 1.25 microg/ml. Up to 8 fetuses were removed at 15 min intervals from the start of the infusion and umbilical vein pH was measured, together with bupivacaine and pethidine concentrations, in fetal plasma, fetal brain and maternal plasma sampled synchronously. Mean umbilical vein pH fell with time with no significant difference between the groups. Maternal plasma concentrations of both drugs did not alter significantly during the experiment. Maternal clearance of bupivacaine was 85.6 ml/min and of pethidine was 249 ml/min. Despite the three-fold higher maternal plasma concentrations of bupivacaine, concentrations of pethidine in fetal plasma and brain were consistently higher than those of bupivacaine. Fetal plasma pethidine concentrations rose 0.276 microg x ml(-1)h(-1) and bupivacaine concentrations rose 0.184 microg x ml(-1)h(-1). The mean (+/-SD) maximum fetal: maternal plasma ratio for bupivacaine was 0.361+/-0.127 and for pethidine 1.78+/-0.81. The fetal brain:plasma ratio of pethidine was consistently higher than that of bupivacaine and did not change significantly with time, whereas that of bupivacaine fell significantly (P<0.05). Concentrations of bupivacaine and pethidine in fetal and maternal brain were consistently higher with adrenaline, although adrenaline had no significant effect on the concentrations in this or any compartment.

Journal Article↗
PubMed1990

Effect of umbilical perfusate pH and controlled maternal hypotension on placental drug transfer in the rabbit.

The purpose of this study was to explore the effect that fetal acidosis and poor maternal placental blood flow may have on the rate of passage across the placenta of drugs commonly used in labor: bupivacaine and meperidine. The rabbit placenta perfused in situ on the fetal side was used, and antipyrine (phenazone) was included as an index of placental exchange and of maternal placental flow. Bupivacaine and meperidine (both 1.25 mg/mL) and antipyrine (4 mg/mL) were infused into a maternal external jugular vein, at 3 mL/h, after loading, in seven anesthetized does. A single placenta in each doe was perfused via the umbilical arteries with Krebs' bicarbonate buffer at pH 7.5 (phase 1), 7.0 (phase 2), and 7.5 (phases 3-5). During phase 4 maternal blood was withdrawn so as to reduce maternal arterial pressure by 35%, and in phase 5 it was reinfused. Concentrations of drugs were measured during each of the five phases in maternal arterial plasma (Cma) and in the effluent perfusate collected from the umbilical vein (Cuv). From these data, placental clearance rates (Cuv x umbilical flow/Cma) were calculated for each drug at each phase. Clearance of bupivacaine and meperidine increased (P less than 0.03) during phase 2, whereas that of antipyrine did not. Clearance of meperidine and antipyrine, but not of bupivacaine, decreased during phase 4. If these results can be extrapolated to the clinical situation, they suggest that the adverse effects of drugs may well be exacerbated in the presence of fetal compromise.

Anesthesia, Obstetrical↗
PubMed1989

Effect of vecuronium on atropine-induced changes in heart rate.

The effect of vecuronium on the heart rate response to atropine has been studied by comparing dose-response relationships in two groups of patients who underwent extracorporeal shock wave lithotripsy. One group received vecuronium (0.1 mg/kg) and the other acted as control. Incremental doses of atropine (1.8, 1.8, 3.6, 7.2 and 14.4 micrograms/kg) were administered and changes in heart rate recorded. No significant differences were observed between the two groups following each incremental dose of atropine.

Adult↗
PubMed1989

The attitudes of junior anaesthetists to research. A survey.

A survey was undertaken to investigate aspects of research work undertaken by junior anaesthetists. Two hundred and ninety-five junior anaesthetists were surveyed. Forty-seven percent of respondents were involved actively in research activities at the time of the survey, although 57% of senior house officers and registrars and 30% of senior registrars would not attempt to acquire publications except to improve their curriculum vitae. Few had received any formal training in research methods. The significance of these findings is discussed with regard to current training opportunities.

Adult↗
PubMed1987

An epidural infusion technique for labour.

A regimen to facilitate control of epidural infusions in labour has been developed which allows midwives to alter infusion rates to maintain satisfactory analgesia. The technique was used successfully in 30 patients and, in a prospective study, was compared with women who received conventional top-up epidurals. It was found that infusions provided comparable analgesia and decreased midwife workload but resulted in a higher dosage of bupivacaine.

Adult↗