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Biomedical subjects

J W Ritchie

Publications and source records attributed to J W Ritchie.

At least 55 records · Page 3Linked to original sources
PubMed1986

The effect of maternal consumption of alcohol on human umbilical artery blood flow.

A Doppler ultrasound technique was used to measure the effect on human umbilical artery impedance of a single moderate dose of alcohol consumed by mothers compared to a control solution in six normal third-trimester pregnancies. No significant difference in impedance was detected between the alcohol and the control solutions during the subsequent 90 minutes. The results suggest that the known toxicity of maternally ingested alcohol is probably mediated by some mechanism other than a significant acute alteration in fetoplacental blood flow characteristics.

Blood Flow Velocity↗
PubMed1986

Antenatal diagnosis of placental anastomosis in a twin pregnancy using Doppler ultrasound.

Qualitative analysis of blood velocity in the umbilical arteries of twin fetuses detected by pulsed Doppler ultrasound revealed discordant patterns which permitted an accurate antenatal diagnosis of an artery-to-artery anastomosis. One twin was consistently larger than the other, had a normal umbilical artery impedance and survived; the other fetus was consistently smaller, had persistently high umbilical artery impedance and died in utero. The death of one fetus did not affect the blood flow patterns within the umbilical artery of the other up to delivery 24 h later. The case demonstrates that intrauterine morbidity due to vascular anastomoses is not confined to the transfusion of significant amounts of blood from one fetus to another.

Adult↗
PubMed1985

Microaerophilic/anaerobic bacteria as a cause of urinary tract infection in pregnancy.

The involvement of microaerophilic/anaerobic bacteria as a cause of urinary tract infection was investigated by appropriate culture of urine samples obtained after periurethral toilet from 48 pregnant women admitted to hospital with urinary tract symptoms. Significant bacterial counts were demonstrated in 28 of these patients; 24 were due to microaerophilic/anaerobic organisms, and the remaining four were due to established urinary pathogens. In 25 pregnant women admitted without urinary tract symptoms, who were used as controls, four had significant bacterial counts, all of which were due to microaerophilic/anaerobic organisms. It is concluded that these organisms may be responsible for urinary tract symptoms in pregnant women when no significant growth is demonstrated on urinary culture by conventional methods.

Bacteriuria↗
PubMed1985

Quantitative measurement of fetal blood flow using Doppler ultrasound.

Blood flow in the descending human fetal aorta and in the intra-abdominal portion of the umbilical vein was quantified using pulsed Doppler ultrasound in a longitudinal series of normal pregnancies, the accuracy of the method having been verified in vitro. The results obtained are in keeping with previous studies but indicate that, although the method is relatively simple, determination of absolute blood flow in these vessels has little clinical potential because of inherent measurement inaccuracies.

Aorta, Thoracic↗
PubMed1985

Umbilical artery blood flow characteristics in normal and growth-retarded fetuses.

Time-velocity waveforms or sonograms obtained by pulsed Doppler ultrasound from the umbilical artery were analysed in a longitudinal study of 15 normal pregnancies. The sonograms from nine fetuses with intrauterine growth retardation were compared qualitatively and had quite different characteristics implying a high distal impedance to blood flow. Methods of analysis capable of differentiating between the normal and abnormal sonograms are described and discussed.

Blood Flow Velocity↗
PubMed1984

A continuing use for Kielland's forceps?

A retrospective study over a 5-year period compared neonatal outcomes after birth by Kielland's forceps with those after caesarean section in the second stage of labour. The 253 babies born by these two modes of delivery showed no difference in Apgar score, the need for active resuscitation, incidence of jaundice or abnormal neurological behaviour. The neonatal outcome was no worse in the small number of patients where Kielland's forceps delivery was attempted but failed. This study offers support for the continuing role of Kielland's forceps in modern obstetrical practice.

Adult↗
PubMed1984

The rate and regularity of breathing movements in the normal and growth-retarded fetus.

The rate and regularity of fetal breathing movements (FBM) were determined in 14 women with uncomplicated singleton pregnancies, eight of whom were between 30 and 33 weeks gestation and six between 37 and 40 weeks gestation. Similar observations were made in 19 women with pregnancies complicated by severe intrauterine growth retardation, 11 of whom were between 30 and 33 weeks and eight between 37 and 40 weeks. In normal pregnancy recordings of breath-to-breath intervals showed that FBM became more regular with advancing gestational age, and the rate [breaths/min, mean (SEM)] slowed from 57.2 (1.3) at 30-33 weeks to 47.9 (0.8) at 37-40 weeks. FBM in the growth-retarded group were regular at each gestation studied and the rate was even slower than in the normal group at term, being 41.9 (1.2) at 30-33 weeks and 41.1 (1.0) at 37-40 weeks. Hyperoxia and hypercapnia appeared to have no consistent effect on fetal breathing rate. Fasting for greater than 12 h considerably reduced the rate of FBM in the normal fetus but only marginally so in those with growth retardation. It is concluded that the pattern of FBM provides more information about the fetus than the amount of time spent breathing, particularly when growth is retarded.

Carbon Dioxide↗
PubMed1984

Induction of labor using high-dose or low-dose prostaglandin vaginal pessaries.

Two hundred women were studied in a randomized controlled trial of induction of labor using high-dose (3 mg) or low-dose (0.5 mg) prostaglandin E2 vaginal pessaries. Induction using 3-mg pessaries was more successful, with a shorter overall induction-delivery interval and less requirement for analgesia, although uterine hyperstimulation occurred in two patients. In contrast, the low-dose regimen did not cause hypertonus and, though less successful in inducing labor, the total dose of prostaglandin E2 used was considerably less than in the 3-mg group. The cesarean section rate when the cervix was initially unfavorable was high in both groups (high dose 18.2%, low dose 16.7%). The response to prostaglandin E2 did not relate closely to the initial cervical state.

Cesarean Section↗
PubMed1984

Fetal breathing movements and lung maturation in the congenitally abnormal human fetus.

Fetal breathing movements have been studied in conjunction with features of anatomical and biochemical development of the lung at birth in fetuses with congenital abnormalities affecting the respiratory system. Total absence of fetal breathing movements or abnormal fetal breathing movements were associated with lung hypoplasia and failure of normal surfactant release into saline extracts of lung fluid. Surfactant synthesis was demonstrated regardless of the presence or absence of fetal breathing movements. The study supports the hypothesis that normal fetal breathing movements are important for fetal lung development and suggests that surfactant synthesis and its release are independent. The latter process may be dependent upon fetal breathing movements while the former is not.

Congenital Abnormalities↗
PubMed1983

Fetal breathing movements and maternal hyperoxia in the growth retarded fetus.

The effect of fetal breathing movements (FBM) of maternal breathing of 50% oxygen was examined. The procedure caused a two-fold rise in maternal arterial Po2 and did not alter FBM in normal pregnancy. In pregnancy complicated by intrauterine growth retardation (IUGR) a substantial increase in the incidence of FBM was recorded during hyperoxia (control 29.8 +/- 3.9%, hyperoxia 68.2 +/- 3.6). No such change was observed in pregnancies where IUGR was suspected but not proven at delivery.

Female↗
PubMed1983

The effects of adrenergic blockade on fetal response to hypoxia.

The actions of the adrenergic blocking agents propranolol and phentolamine upon the responses of 124-135 days fetal sheep to hypoxia induced by causing pregnant ewes to breathe 9% O2 and 3% CO2 in N2 have been studied. During hypoxia fetal heart rate fell and any tendency for this to return was prevented by propranolol and stimulated by phentolamine. The ability of the fetal heart rate to return during hypoxia appears to be related to the rise in plasma catecholamines. Hypoxia induced increases in plasma ACTH and cortisol and in plasma metabolites appear to have the same characteristics as those changes induced by catecholamine infusion; the former being largely an alpha-receptor effect and the latter being beta-receptor mediated. The results indicate but do not prove that many of the fetal responses to hypoxia could be caused by the rise in plasma catecholamines.

Adrenocorticotropic Hormone↗
PubMed1983

The effects of hypoxia on glucose turnover in the fetal sheep.

The origin of the hypoxia-induced rise in fetal blood glucose concentration in fetal sheep of 124-135 days was investigated. Hypoxia was induced in pregnant sheep and fetuses with chronically implanted vascular catheters by causing the ewes to breathe 9% O2 and 3% CO2 in N2 for 60 min. The rise in fetal plasma glucose caused by a 60% reduction in maternal PaO2 was associated with a 50% fall in plasma insulin concentration. The fall in insulin and rise in glucose was prevented by the alpha-adrenergic blocking agent phentolamine but not by the beta-antagonist propranolol. Turnover of glucose in the fetus under these conditions was measured with [6-3H] and [U-14C] glucose. Hypoxia reduced fetal glucose consumption despite the hyperglycaemia. After 30 min of hypoxia there was no evidence of fetal production of glucose but by 60 min substantial production was evident. The reduced fetal consumption and increased production of glucose was inhibited by phentolamine but not by propranolol. It is concluded that in the fetal sheep hypoxia induced hyperglycaemia is first caused by reduced consumption of glucose and thus fetal glycogen stores are not depleted. If the hypoxia persists fetal blood glucose is elevated further by fetal production of glucose.

Animals↗
PubMed1981

Perinatal death recording: time for a change?

The new perinatal death certificate proposed by the World Health Organisation was examined in relation to existing measures for recording perinatal death statistics and also with regard to new information gathered. Present procedures appear to underestimate the number of perinatal deaths by roughly 10%, though late registrations may lower this figure slightly. The use of a minimum birth weight as the criterion for inclusion in perinatal statistics removed much of the uncertainty associated with definitions of live birth and stillbirth. The new certificate led to duplication of some information already recorded through birth notification yet failed to provide information on some other factors generally considered relevant to perinatal mortality. The format proposed for recording cause of death provided a more logical presentation of events. Standardizing birth information recorded on all infants, modifying death certificates, and developing efficient record-linkage schemes would be more valuable than introducing the WHO certificate. Useful interpretation of the meaning of the characteristics of infants dying in the perinatal period awaits these timely changes.

Death Certificates↗