Biomedical subjects

D Caton

Publications and source records attributed to D Caton.

At least 55 records · Page 3Linked to original sources

PubMed1977

[The effect of local anaesthetics on uterine blood flow and O2-consumption in pregnant sheep (author's transl)].

The local anesthetics bupivacaine, etidocaine, lignocaine and chloroprocaine were infused intravenously for 30 min to pregnant sheep, prepared for chronic studies. The amide compounds reached highere plasma concentrations than chloroprocaine. All local anaesthetics decreased uterine blood flow and O2 consumption without marked alterations of arterial or uterine venous blood gases. These changes were within the wide physiological range of variation, which was established in controls during 24 h. The findings may be of significance during paracervical block or pathological states of UBF or fetal homeostasis.

Anesthetics, Local↗

PubMed1976

Uterine blood flow, oxygen consumption, and maternal plasma estradiol and progestins following fetal death.

Fetuses of 42 near-term sheep were killed while they were in utero. Uterine blood flow, oxygen consumption, A-V O2, and maternal arterial plasma concentrations of estradiol and progestins were observed for the next 4 hours. There was an immediate (88 per cent) fall in oxygen consumption; blood flow decreased by 50 per cent within 30 minutes. Hormone concentrations changed, but only after 2 hours. Circulatory changes appeared to be related to local changes within the uterus, particularly to decomposition of the chorioallantoic membrane. This relationship was best seen in the experiments in which one of a set of twins was killed. The experiments are in accord with the theory that the rate of uterine blood is not directly related to acute changes in respiratory gases nor to plasma concentrations of certain hormones.

Animals↗

PubMed1976

Automatic balance for fetal weight studies.

An automatic balance was constructed of aluminum sheet, miniature ball bearings, and a strain gauge. The balance was capable of measuring 1 to 4 kg. with an accuracy of +/- 0.5 Gm. and a 95 per cent response time of less than 0.3 seconds. Fetuses of term ewes were exteriorized and weighed continuously for up to 3 hours. Rapid depletion of the ewe's blood volume led to a 10 to 24 per cent increase in estimated fetal blood volume. Fetal weight loss occurred regularly during reversible occlusion of the umbilical veins.

Animals↗

PubMed1975

The circulating plasma volume of the foetal lamb as an index of its weight and rate of weight gain (g/day) in the last third of gestation.

In a series of foetal lambs weighing between 1,100 and 5,228 g, the circulating plasma volume was estimated by the dye dilution method, using Evans Blue, to test the possibility that the plasma volume could be used as an index of foetal weight in chronic studies. The data, analysed by the method of least squares regression, indicate that plasma volume and foetal weight are closely correlated (R-2 equals 0.922) and linearly so in the range of data studied. There was no evidence that the relation differed for singlets and twins. A single equation, Y equals 71.8 plus 10.11 X--where Y is the estimated weight and X the plasma volume, can be used to predict the weight from plasma volume in both. Some results of the application of the method in chronic studies are presented.

Animals↗

PubMed1974