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Biomedical subjects

C R Whitfield

Publications and source records attributed to C R Whitfield.

At least 37 records · Page 2Linked to original sources
PubMed1983

Amniotic fluid phospholipid profile in multiple pregnancy and the effect of zygosity.

Because respiratory distress syndrome (RDS) may occur in one twin but not the other it may be misleading to assess fetal lung maturity using amniotic fluid from only one sac. We compared the amniotic fluid lecithin/sphingomyelin (L/S), phosphatidyl glycerol/sphingomyelin (PG/S) and phosphatidyl inositol/sphingomyelin (PI/S) ratios between co-twins and co-triplets in 32 sets of twins and three set of triplets. In the twin pregnancies we found a weak correlation for L/S ratio but a much improved one for PG/S and PI/S. The concordance between sacs for all three ratios was better in monozygotic than in dizygotic twins. The efficacy of amniotic fluid PG in the determination of fetal lung maturity was demonstrated and the discrepancies between the sacs was much less for PG than for the L/S ratios. Employing the L/S ratio combined with the presence or absence of PG should reduce false results to a minimum.

Amniotic Fluid↗
PubMed1983

Amniotic fluid phosphatidylglycerol: an early indicator of fetal lung maturity.

In a study of 766 amniotic fluids, collected from pregnancies between 26 weeks and term, phosphatidylglycerol (PG) was identified in a greater proportion than was a mature lecithin/sphingomyelin (L/S) ratio at all gestational ages between 28 and 38 weeks regardless of the underlying pregnancy complication. The early appearance of PG was particularly striking in amniotic fluids obtained after preterm rupture of membranes. Since PG has been previously shown to be a useful indicator of the risk of neonatal respiratory distress syndrome, its appearance before a mature L/S ratio suggests that its detection offers a considerable advantage in the management of high-risk obstetric problems in which the earliest possible indication that the fetal lungs are mature is required.

Amniotic Fluid↗
PubMed1982

Fetal cardiac electromechanical intervals during labour and effects of hypoxia and cord compression.

Cardiac electromechanical intervals were measured during labour in 103 unselected human fetuses. Mean values (+/- SD) for the three intervals measured were 76.01 +/- 9.93 ms for the pre-ejection period, 41.56 +/- 8.51 ms for the isovolumetric contraction time and 156.23 +/- 16.58 ms for the left ventricular ejection time. These are consistent with previously reported data from our own and other centres. the intervals studied did not alter significantly as labour proceeded or during uterine contractions. There was no consistent correlation between them and fetal scalp blood PO2, PCO2 or pH, although the pre-ejection period was shortened considerably in three very acidaemic or hypoxic fetuses, and it was prolonged in association with tight nuchal cord entanglement and variable decelerations in fetal heart rate. These findings raise the possibility of using recorded cardiac electromechanical intervals to determine the clinical significance of different fetal heart-rate patterns that suggest the possibility of fetal distress.

Constriction, Pathologic↗
PubMed1982

Amniotic fluid phosphatidylglycerol and the lecithin/sphingomyelin ratio in the assessment of fetal lung maturity.

Based on the analysis of 561 amniotic fluid samples obtained within 72 h of delivery, including 288 samples collected from the vagina, the detection of phosphatidylglycerol (PG) in the fluid together with the determination of the lecithin/sphingomyelin (L/S) ratio gave an accurate prediction of the risk of the newborn infant developing respiratory distress syndrome (RDS). In the presence of PG, regardless of the L/S ratio, only 0.6% of the babies developed RDS, while absent PG was associated with an 82.8% incidence of RDS. The predictive ability was improved by knowing the L/S ratio since in the presence of both PG and a mature L/S ratio (greater than 2.0), no baby developed RDS whereas 3.4% of them did when the ratio was immature despite the presence of PG. The test appears to be a useful determinant of the risk of RDS in babies born to diabetic mothers and it seems particularly effective in assessing amniotic fluid collected vaginally. It is recommended that laboratories dealing with amniotic fluid from high-risk pregnancies should detect PG as well as measuring the L/S ratio.

Amniotic Fluid↗
PubMed1981

Amniotic fluid phospholipid profile determined by two-dimensional thin-layer chromatography as index of fetal lung maturation.

A phospholipid profile, the main features of which were the lecithin/sphingomyelin (L/S) ratio and the presence or absence of phosphatidylglycerol (PG), was determined in amniotic fluid from 188 patients. There was a mature profile (L/S ratio of at least 2 . 0 and detectable PG) in 145 patients, including seven insulin-dependent diabetics, and noe of their babies developed respiratory distress syndrome (RDS). The L/S ratio was less than 2 . 0 and PG absent in 12 patients, nine of whose babies developed RDS, whereas only three small babies (delivered between 28 and 35 weeks because of fulminant pre-eclampsia or severe abruptio placentae) out of 31 developed RDS when the L/S ratio was less than 2 . 0 but PG was present. When amniotic fluid was collected from the vagina only one out of 69 babies developed RDS when PG was present (regardless of the L/S ratio), while all of seven babies developed RDS when PG was absent. It is concluded that the amniotic fluid phospholipid profile, particularly the presence or absence of PG, gives an accurate assessment of fetal lung maturation. The profile may prove a useful adjunct to the management of high-risk pregnancies, especially after premature membrane rupture and perhaps also when the mother is diabetic.

Amniotic Fluid↗
PubMed1980

Screening for the small-for-dates fetus: a two-stage ultrasonic examination schedule.

To find an effective routine screening method for small-for-dates fetuses 474 women with singleton pregnancies participated in a two-stage ultrasonic examination schedule. At the first-stage examination, which was conducted in early pregnancy, fetal crown-rump length or biparietal diameter was measured for an accurate assessment of gestational age, which was essential for interpreting the results of the second-stage examination. The second-stage examination was performed at 34-36 weeks and entailed measuring seven fetal variables, the results of which were assessed singly and in combination after delivery to identify the best indicator of small-for-dates fetuses. Fetal head measurements proved to be the least sensitive indicators of growth retardation, correctly identifying only 56-59% of cases. Measurements of trunk area and circumference, however, correctly identified 81% and 83% of cases respectively, but the most effective screening index was the product of crown-rump length and trunk area: with this index 34 out of 36 small-for-dates fetuses (94%) were correctly identified. Calculating the product of crown-rump length and trunk area from ultrasonic displays is quick and simple, and combined with the first-stage examination is a highly reliable screening method for small-for-dates fetuses.

Anthropometry↗
PubMed1975

The uterine and cardiovascular effects of salbutamol and practolol during labour.

Intravenous salbutamol, a beta-adrenoceptor stimulant, given to nine patients in normal labour, with continous monitoring of uterine activity and of the maternal and fetal cardiovascular systems, was shown to decrease uterine activity significantly; maternal and fetal heart rates were significantly increased, and maternal systolic and diastolic arterial pressures were significantly decreased during the infusion, although no treatment had to be discontinued because of these effects. Apart from worsening of low back pain during the infusion in one patients, subjective side-effects were trival. With the salbutamol infusion continued at an effective maintenance rate, the carioselective beta-adrenoceptor blocking drug, practolol, given intravenously, reduced the maternal heart rate (although not significantly) but it did not alter the fetal heart rate; it also appeared to interfere transiently with the inhibiting action of salbutamol on uterine activity, but cerevical dilatation was arrested until the salbutamol infusion was discontinued. At least in five patients, labour remained suppressed until oxytoxin was infused intravenously.

Albuterol↗
PubMed1975

Estimation of fetal weight from ultrasonic measurement of trunk circumference.

A new method of estimating fetal weight from the circumference of the fetal trunk, measured by ultrasound, is described. Comparison of weights estimated in this way with the actual birth weights of 50 fetuses, delivered not more than 48 hours later, shows a mean error in prediction of only 75 g, and in 94 per cent the error was less than 145 g. With such accuracy, the method is of clinical value, particularly in anticipating difficult delivery and in monitoring growth of the fetus at risk.

Abdomen↗