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Biomedical subjects

S Chua

Publications and source records attributed to S Chua.

At least 73 records · Page 4Linked to original sources
PubMed1994

Intrauterine pressure: comparison of extra vs intra amniotic methods using a transducer tipped catheter.

Fourteen women admitted in early labor, with intact membranes, were studied. In each woman, two catheters were inserted transcervically; one catheter was inserted into the extraamniotic space before rupture of membranes, and the second catheter was inserted, after artificial rupture of membranes into the intraamniotic cavity. The contraction to contraction difference in active pressure (pressure above the baseline) recorded by the two catheters, as well as the cumulative total active pressure generated (calculated by adding the active pressure of all contractions) throughout labor by the two catheters were compared. Of the 606 contractions analysed, 43.2% showed pressure difference of 0-5 mmHg between the intra amniotic and extraamniotic catheter; 21.3% showed 6-10 mmHg difference, 12.2% showed a difference of 11-15 mmHg, and 23.3% showed a difference greater than 15 mmHg. When total active pressure generated by each catheter for individual patients was calculated, the percentage difference varied from 2.3% to 53.7%. Intrauterine pressure measurements in labour using transducer-tipped catheters inserted in the extraamniotic space may not provide comparable information to a similar catheter inserted intraamniotically when membranes are ruptured.

Amnion↗
PubMed1994

Glycosylated hemoglobins in pregnant women with normal and abnormal glucose tolerance.

Glycosylated hemoglobin (HbA1) levels were compared in low risk pregnant Singaporean women with normal and abnormal glucose response. HbA1 (mean +/- 1 SD) levels in normal and abnormal groups (489 and 72, respectively) were 4.65 +/- 0.49 and 4.85 +/- 0.50, respectively. While mean levels were significantly different, there was a considerable overlap of levels in both groups. At various gestation periods, mean HbA1 levels between normal and abnormal groups showed significant difference only at late gestation. The latter may have contributed to significant differences in HbA1 levels between normal and abnormal groups as a whole. The considerable overlap of HbA1 values in normal and abnormal groups indicate that HbA1 may be insensitive as a screening method for glucose intolerance.

Biomarkers↗
PubMed1993

The glucose challenge test: a screening test for gestational diabetes mellitus.

The 50g glucose challenge test (GCT) was evaluated as a method to screen for gestational diabetes in 540 low-risk pregnant women to establish its sensitivity and specificity, as well as to establish a relevant threshold plasma glucose value above which a diagnostic 75g oral glucose tolerance test (OGTT) would be indicated. If a threshold of 140 mg/dl is used, the diagnostic yield would be 28.5%. At a threshold of 130 mg/dl, the diagnostic yield fell to 25.4%; the sensitivity rose to 87.7% and the specificity declined to 67.1%. There was progressive increase in diagnostic sensitivity when the GCT was performed after 24 weeks without significant decrease in specificity. In low-risk populations, a 50g GCT should be performed between 24-28 weeks gestation.

Blood Glucose↗
PubMed1992

Prognosis for pre-eclampsia complicated by 5 g or more of proteinuria in 24 hours.

Forty-two women with pregnancies complicated by pre-eclampsia and heavy proteinuria greater than or equal to 5 g/24 h were referred for conservative management to the high-risk obstetric unit in the John Radcliffe Hospital, Oxford, over a period of 5 years. Hyperuricaemia preceded the onset of heavy proteinuria in all 42 women. Most of the women had severe hypertension, but none developed eclampsia and there were no major maternal complications. Delivery was necessary within 2 weeks of onset of severe proteinuria in 88.1% of cases, although in some very preterm pregnancies delivery could be deferred for 3 or more weeks. Thirty-five women (83%) were delivered by caesarean section, 91% of whom were delivered urgently before the onset of labour. The high rate of urgent preterm operative delivery underlines the uncertainty of advanced pre-eclampsia and the need for close monitoring if delivery is to be deferred. Perinatal mortality was high; all the perinatal deaths occurred in babies of less than 29 weeks gestation. Despite heavy proteinuria, postpartum recovery was good. Three months after delivery, all but one patient had no significant proteinuria. There was no evidence of residual renal dysfunction. Although the outlook for pre-eclampsia with heavy proteinuria is limited, in a few cases pregnancy can be prolonged for significant periods of time without apparently prejudicing maternal safety and permitting enhancement of maturity at birth. The observations justify cautious conservative management even when heavy proteinuria is present.

Antihypertensive Agents↗
PubMed1992

In-utero sound levels when vibroacoustic stimulation is applied to the maternal abdomen: an assessment of the possibility of cochlea damage in the fetus.

OBJECTIVE: To measure sound pressure level in utero while a vibro acoustic stimulator is applied to maternal abdomen and to calculate whether the estimated effect on fetal cochlea cilia vibration would be hazardous. DESIGN: Prospective descriptive study. SETTING: Labour ward, National University Hospital, Singapore. SUBJECTS: Eight women undergoing induction of labour. INTERVENTION: A hydrophone was introduced via the cervix into the uterus and placed under ultrasound guidance near the fetal ear. Sound pressure was recorded when a vibroacoustic stimulator was applied directly to the maternal abdomen and also when separated by 2 cm of air. MAIN OUTCOME MEASURES: Sound pressure levels in utero. RESULTS: The sound level recorded from the vibrator diaphragm in air was 107 dB at 2 cm and 74 dB at 1 m. The mean sound pressure level in utero was 90.7 dB (range 75-96 dB) when the vibrator was in contact with the abdominal wall and 80.1 dB (range 70-88 dB) when separated by 2 cm of air. CONCLUSIONS: Analysis of factors affecting displacement of cochlear sensing cilia in utero show that, for equal sound pressures, sound intensity and sound vibration are about 4000 times less in amniotic fluid, compared to that produced in air. Further protection is provided by viscous and hydrodynamic features of the ear. The estimated effect on cilia vibration by the mean sound pressure registered in utero, about 90 dB, corresponds to that produced postnatally by an airborne sound registering about 40 dB, which would not be hazardous.

Cochlea↗
PubMed1992

The accuracy of catheter-tip pressure transducers for the measurement of intrauterine pressure in labour.

OBJECTIVE: To assess the reliability of intrauterine pressure measurements in labour with transducer tipped catheters. DESIGN: Prospective clinical study. SETTING: Delivery ward, National University Hospital, Singapore. SUBJECTS: 20 women admitted in early labour were randomly allocated to two groups. INTERVENTIONS: Women in the first group had two catheters that had been tied together introduced transcervically into the same amniotic fluid pocket. The second group had two catheters introduced in different directions so that each catheter tip was in a different pocket of amniotic fluid. MAIN OUTCOME MEASURE: The contraction to contraction pressure difference recorded by the two catheters in the same uterus. In addition, the cumulative uterine active pressure generated by one catheter was compared with that of the other. RESULTS: There were differences in peak pressure of up to 4-5.3 kPa (30-40 mmHg) during some contractions. The difference in pressure recordings between the two catheters could not be explained by effects of loculation of amniotic fluid. However, the pressures recorded were not systematically higher in one catheter than in the other. Cumulative uterine activity was very similar when assessed by each catheter in the same uterus. CONCLUSION: Intrauterine pressure measurements using transducer tipped catheters provide reliable information on the cumulative pressure wherever the catheter tip was sited in the uterus, but there are variations in pressures recorded during individual contractions.

Catheterization↗
PubMed1992

Symptoms and signs with scar rupture--value of uterine activity measurements.

To evaluate the symptoms and signs of scar rupture with special reference to intrauterine pressure measurement a retrospective analysis of labour records of those women who had trial of labour with a previous Caesarean scar in the National University Hospital over a period of 6 years (1985-1990) was carried out. Known symptoms and signs associated with scar rupture, cardiotocographic tracings and fetal and maternal outcome in these patients were studied. Of the 1,018 women with previous Caesarean scar (4.2% of our pregnant population at term) 722 (70.9%) had trial of labour; 70% delivered vaginally. There were 4 (0.55%) incomplete and 5 (0.69%) complete scar ruptures. All 9 women had an oxytocin infusion; 3 were diagnosed postdelivery (all 3 had complete ruptures); 3 of the 6 who had rupture prior to delivery had sudden reduction in uterine activity, 1 had scar pain and prolonged bradycardia and 2 had no symptoms or signs. Continuous cardiotocography with intrauterine pressure measurements may help to identify scar rupture early and may be of value especially in those who have an oxytocin infusion.

Apgar Score↗
PubMed1991

Congenital heart block with hydrops fetalis treated with high-dose dexamethasone; a case report.

A 32-year-old woman with systemic lupus erythematosus was found to have a fetus with heart block and fetal ascites at 23 weeks gestation. Treatment with high-dose corticosteroids ameliorated the early signs of heart failure, although the fetal heart rate gradually fell from 48 beats/min to 42 beats/min by 34 weeks. Sudden deterioration of the fetal state occurred at 35 weeks, and this only partially responded to digitalisation. Neonatal death occurred on Day 18 from the consequences of severe birth asphyxia. The relationship and pathogenesis of anti-Ro antibodies, congenital heart block and hydrops fetals are discussed, together with the in utero management of this condition.

Adult↗
PubMed1991

Short- and long-term results of catheter balloon percutaneous transvenous mitral commissurotomy.

Percutaneous transvenous mitral commissurotomy (PTMC) was performed in 219 patients with symptomatic, severe rheumatic mitral stenosis. There were 59 men and 160 women, aged 19 to 76 years (mean 43). Pliable, noncalcified valves were present in 139 (group 1), and calcified valves or severe mitral subvalvular lesions, or both, in 80 patients (group 2). Atrial fibrillation was present in 133 patients (61%) and 1+ or 2+ mitral regurgitation in 59 (27%). Technical failure occurred with 3 patients in our early experience. There was no cardiac tamponade or emergency surgery. The only in-hospital death occurred 3 days after the procedure in a group 2 premoribund patient in whom last-resort PTMC created 3+ mitral regurgitation. Mitral regurgitation appeared or increased in 72 patients (33%); 3+ mitral regurgitation resulted in 12 patients (6%). There were 3 systemic embolisms. Atrial left-to-right shunts measured by oximetry developed in 33 patients (15%). Immediately after PTMC, there were significantly reduced (p = 0.0001) left atrial pressure (24.2 +/- 5.6 to 15.1 +/- 5.1 mm Hg), mean pulmonary artery pressure (39.7 +/- 13.0 to 30.6 +/- 10.9 mm Hg) and mitral valve gradient (13.0 +/- 5.1 to 5.7 +/- 2.6 mm Hg). Mitral valve area increased from 1.0 +/- 0.3 to 2.0 +/- 0.7 cm2 (p = 0.0001) and cardiac output from 4.4 +/- 1.4 to 4.7 +/- 1.2 liters/min (p less than 0.01). The results mirrored clinical improvements in 209 patients (97%). Multivariate analysis showed an echo score greater than 8, and valvular calcification and severe subvalvular lesions as independent predictors for suboptimal hemodynamic results.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Uterine activity in dysfunctional labour and target uterine activity to be aimed with oxytocin titration.

Uterine activity was quantified using a transducer tipped intrauterine catheter in 75 nulliparous women with dysfunctional labour. The active contraction area profiles in these women were below the median levels reported for those who had normal progress of labour from our institution. When uterine activity was augmented with oxytocin, 90.7% progressed in labour and delivered vaginally. Six patients (8%) showed poor progress despite good uterine activity and had to be delivered by caesarean section (CS) for failure to progress and signs of cephalopelvic disproportion. The pre- and post-augmentation uterine activity were similar in those who delivered vaginally or by CS and was not helpful in identifying those who had cephalopelvic disproportion. Of the 75 women who had slow progress of labour, 50 had a contraction frequency of less than 1 in 3 min whilst 25 had a minimum frequency of 1 in 3 min or more. All except one in the latter group delivered vaginally when oxytocin was titrated to achieve a contraction frequency of 1 in 2 to 2 1/2 min which were clinically judged to be adequate based on a duration greater than 40 sec. Oxytocin should be titrated to achieve a target contraction frequency of 1 in 2 to 2 1/2 min lasting greater than 40 sec to achieve good obstetric outcome in those with dysfunctional labour.

Adult↗
PubMed1991

A comparison between fibreoptic and catheter-tip bridge strain gauge transducers for measurement of intrauterine pressure in labour.

A new fibreoptic pressure transducer was used to measure uterine activity in labour, and the results were compared with those obtained with the catheter-tip bridge strain gauge transducer. Readings were obtained from 8 patients in spontaneous labour, and a total of 565 contractions were analysed. When all contractions were analysed the coefficient of variation ranged from 11.24 to 42.74. In 2 patients with vast difference in pressure readings one of the catheters had slipped into the lower uterine segment, when these 2 cases were not considered the coefficient of variation ranged from 11.24 to 21.18. Even in the others there were transient periods lasting 5 to 15 minutes when the pressure difference was greater than 10 mmHg between the 2 catheters. When they were excluded from analysis, along with the 2 cases where one of the catheters was displaced, the coefficient of variation ranged from 9.30 to 16.05. The fibreoptic pressure transducer appears to be a safe, convenient and fairly accurate means of assessing uterine activity. But one must be aware that a catheter giving low readings compared with the initial period soon after insertion may be due to displacement of the transducer tip to the uterine lower segment.

Evaluation Studies as Topic↗
PubMed1991

Trophoblast deportation in pre-eclamptic pregnancy.

OBJECTIVES: To examine the deportation of trophoblast cells into the maternal blood in pre-eclamptic (gestational proteinuric hypertension) and normal pregnancy. DESIGN: The monoclonal anti-cytokeratin antibody JMB2 was used in the APAAP technique to label trophoblast cells in cell smears of uterine vein blood obtained at caesarean section. SUBJECTS: 10 women with proteinuric pre-eclampsia requiring caesarean section, 10 pregnant women requiring elective caesarean section for reasons other than pre-eclampsia and five control women who had never been pregnant. RESULTS: Three populations of trophoblast cells were identified; two mononuclear cytotrophoblast types with diameters varying from 11-14 microns and 19-25 microns respectively, and multinucleated syncytiotrophoblast cells varying in size from 23-88 microns. Women with pre-eclampsia had more trophoblast cells in uterine vein blood than were found in pregnant women without pre-eclampsia. There was no correlation between the numbers of trophoblast cells and the stage of gestation or severity of the pre-eclampsia, although an acute maternal or fetal event necessitating delivery was associated with increased deportation of trophoblast. Mononuclear cytotrophoblast cells were detected in the peripheral blood of only 1 of 5 pre-eclamptic patients, despite their presence in the uterine vein blood of all 5 women. CONCLUSIONS: Trophoblast deportation is increased in pre-eclamptic pregnancy, with both cytotrophoblast and syncytiotrophoblast present in the uterine vein blood, but there is no correlation with the severity of the disease. In some cases cytotrophoblast may also enter the peripheral circulation.

Antibodies, Monoclonal↗
PubMed1991

Oxytocin titration for induction of labour: a prospective randomized study of 15 versus 30 minute dose increment schedules.

Two hundred and twenty four patients admitted for induction of labour were randomized into 2 groups. The oxytocin dose was escalated every 15 minutes in the first group whilst for the second group the dose was increased every 30 minutes till optimal uterine activity was achieved. There was no significant difference in the mean maximum dose of oxytocin and length of labour in the 2 groups studied. Transient reduction of the dose of oxytocin was needed in 20.5% of patients in the '15 minute' group and 17.0% of cases in the '30 minute' group because of uterine hyperstimulation or fetal heart rate (FHR) changes; this difference was not statistically significant. The incidence of operative deliveries were similar in the 2 groups. The neonatal 1 and 5 minute Apgar scores, cord arterial blood pH, incidence of assisted ventilation and admission to the neonatal intensive care unit were similar in the 2 groups. The 15 minute schedule does not offer any advantage over the 30 minute escalation schedule for induction of labour. Hyperstimulation and FHR changes are a possibility with any regimen and close monitoring of FHR and uterine activity is advisable with the use of oxytocin.

Apgar Score↗