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Biomedical subjects

K Fong

Publications and source records attributed to K Fong.

At least 19 recordsLinked to original sources
PubMed1996

Doppler velocimetry of the fetal middle cerebral and renal arteries: interobserver reliability.

Using color and pulsed Doppler ultrasonography, the interobserver reliability of measurements in the fetal circulation was evaluated in 41 pregnancies of 25 to 39 weeks' gestation. Two observers recorded flow velocity waveforms from the middle cerebral and renal arteries for measurement of peak systolic, minimum diastolic, and mean velocities, pulsatility index, and resistive index. Intraclass correlation coefficient of reliability was calculated by analysis of variance. Substantial interobserver agreement was found for pulsatility index and minimum diastolic velocity in both arteries. Therefore, these measurements have the greatest clinical applicability.

Adult↗
PubMed1996

The hypocholesterolemic and antiatherogenic effects of topically applied phosphatidylcholine in rabbits with heritable hypercholesterolemia.

To test possible hypocholesterolemic and antiatherogenic effects of transdermally administered phosphatidylcholine (PC), we applied a 33% solution of PC in ethanol containing 0.01% butylated hydroxytoluene as antioxidant, to the shaved back of a strain of inbred rabbits which spontaneously developed hypercholesterolemia (serum cholesterol above 110 mg/dl) and severe atherosclerotic lesions especially in the aortic arch. After the topical application of PC, increases of choline-containing phospholipids in blood were observed, reaching a plateau in 24-48 hr. There were significant reductions in serum cholesterol and LDL cholesterol in the treated animals 2-3 weeks after the treatment. Atherosclerotic lesions in the aortic arch were clearly less severe in the animals repeatedly treated with topical PC. The hypocholesterolemic and antiatherogenic effects of topical PC could be the result of increased cholesterol efflux from extrahepatic tissues and enhanced reverse cholesterol transport.

Administration, Cutaneous↗
PubMed1995

Superior mesenteric artery and renal artery blood flow velocity measurements in neonates: technique and interobserver reliability.

The objective of this study was to establish the interobserver reliability for superior mesenteric artery (SMA) and renal artery (RA) Doppler blood flow velocity (BFV) measurements in neonates. Forty-two clinically stable infants were enrolled, mean (SD) gestational age 33 (2) weeks, birthweight 2.00 (0.54) kg, postnatal age 10 (11) days. Doppler recordings were made by two trained observers. The SMA and RA were studied with a 5.0-MHz phased array transducer. The optimal spectral trace from each artery containing a minimum of five consecutive waveforms was analysed. The peak systolic velocity (PS), end diastolic velocity (ED) and mean peak velocity (MV) were measured and the time-averaged mean velocity (TAV) and waveform indices were calculated. Using the intraclass correlation coefficient (ICC) the estimates of interobserver reliability for different measurements varied from 0.40 to 0.83. Substantial agreement was obtained between observers in the TAV, PS, ED and MV; the ICC varied from 0.72 to 0.83 demonstrating that Doppler BFV measurements of the SMA and RA are reliable in neonates.

Blood Flow Velocity↗
PubMed1995

Aminophylline and Doppler time-averaged mean velocity in the middle cerebral artery in preterm neonates.

OBJECTIVE: The purpose of this study was to assess the effect of an intravenous loading dose of aminophylline (6 mg/kg) on Doppler time-averaged mean velocity in the middle cerebral artery in ventilated preterm neonates. METHODOLOGY: Twenty infants were studied by colour/duplex Doppler technique prior to and at 5, 10, 30 and 60 min after the administration of aminophylline. RESULTS: Aminophylline treatment was associated with a statistically significant reduction in time-averaged mean velocity from baseline (P < 0.001) and an increase in heart rate (P < 0.001) at all timepoints. The largest reduction in time-averaged mean velocity of 19% (95% confidence interval -10 to -28%) occurred at 10 min post-dose. There were no statistically significant changes in transcutaneous PCO2 or mean arterial blood pressure. CONCLUSIONS: The observed reduction of 19% from baseline in time-averaged mean velocity following treatment with aminophylline alone is unlikely to be of clinical importance. Whether aminophylline in combination with other drugs that decrease central blood flow velocity such as indomethacin and/or dexamethasone could result in a clinically significant reduction deserves further study.

Aminophylline↗
PubMed1994

The effect of dexamethasone on time averaged mean velocity in the middle cerebral artery in very low birth weight infants.

The effect of repeated doses of dexamethasone (0.25 mg/kg/dose every 12 h) on time averaged mean velocity in the middle cerebral artery was assessed in ten ventilated very low birth weight infants requiring treatment with dexamethasone for bronchopulmonary dysplasia or airway obstruction. The infants were studied by colour/duplex Doppler technique prior to the administration of the first and the third dose of dexamethasone, and 10, 30, and 120 min after these doses. Dexamethasone treatment was associated with an improvement in infant lung condition, an increase in mean arterial blood pressure and a decrease in heart rate. The time averaged mean velocity was statistically significantly reduced at 120 min after the first dose. This was not associated with a decrease in PCO2. The observed reduction of 18% from baseline in the time averaged mean velocity is unlikely to be of clinical importance.

Airway Obstruction↗
PubMed1994

Uterine and umbilical blood flow velocity during epidural anaesthesia for caesarean section.

The purpose of this study was to use colour Doppler to determine the effect of epidural anaesthesia on the uterine and umbilical blood flow velocities. After determining the precision of the technique, Doppler insonation of the uterine and umbilical arteries was performed in consenting non-labouring patients requesting epidural anaesthesia for Caesarean section. Patients in Group I were normal and those in Group II were at high risk for uteroplacental blood flow abnormalities. The pulsatility indexes (PI) of both uterine and umbilical arteries were compared at the following times: control, after fluid and after anaesthesia using repeated measure analysis of variance. In Group I (n = 30) the PI increased from 0.72 to 0.82 in the left uterine artery and from 0.71 to 0.85 in the right uterine artery (P < 0.05). In Group II (n = 10) the PI increased from 0.67 to 0.85 in the left uterine artery (NS) and from 0.98 to 1.38 in the right uterine artery (P < 0.05). There was no change in the PI in the umbilical artery. We conclude that the PI of the uterine arteries increases after epidural anaesthesia with lidocaine, epinephrine and fentanyl but there is no change in the umbilical PI. While these changes do not appear to be clinically important in the low-risk population, further studies are required to determine the impact on fetuses at high risk for in utero hypoxaemia.

Adult↗
PubMed1993

Trisomy 4 in a fetus with cyclopia and other anomalies.

We report on an 18-week fetus with cyclopia, alobar holoprosencephaly, complex congenital heart defect, anal atresia, oligosyndactyly, cystic hygroma, and skeletal abnormalities with trisomy 4. Structural anomalies were detected on routine ultrasound of the pregnancy of a 17-year-old G3 P1 TAB1 woman with sickle cell trait. Trisomy 4 conceptuses usually miscarry in the first trimester. We are aware of no other reports of a fetus with trisomy 4 and cyclopia. Causal association of chromosome abnormalities and holoprosencephaly sequence may be more apparent in embryos and early fetuses than term fetuses because of poor viability of affected conceptuses.

Abnormalities, Multiple↗
PubMed1993

Effect of indomethacin on cerebral blood flow velocities in very low birth weight neonates with a patent ductus arteriosus.

The effect of repeated doses of indomethacin on mean peak velocity (MPV) and time-averaged mean velocity in the middle cerebral artery was assessed in 10 ventilated neonates with a patent ductus arteriosus using colour/duplex Doppler technique prior to, and 10, 30, and 120 min after the first and the third dose. Velocities were significantly reduced up to 120 min after the first dose. The third dose resulted in a significant reduction in MPV at 10 and 30 min following treatment. This reduction was half of that observed after the first dose. Systemic blood pressure (BP) and heart rate did not change significantly after each separate dose. However, by the third dose, mean and diastolic BP were significantly increased from pretreatment levels. The attenuated response of cerebral blood flow (CBF) velocities to the third dose of indomethacin compared with the first dose is probably related to altered haemodynamics. Indomethacin should be used cautiously in infants with other conditions which are known to decrease CBF such as hypotension, hypocarbia and polycythaemia.

Blood Flow Velocity↗
PubMed1992

Otoacoustic emissions, audiometric sensitivity loss, and speech understanding: a case study.

The clinical measurement of otoacoustic emissions can assist in differentiating between peripheral and central explanations for deficits in speech understanding. We present audiometric and distortion-product emission data in a case with sensorineural hearing loss and a deficit in speech understanding. The presence of evoked emissions argues against attributing the speech audiometric loss to cochlear defect.

Adult↗
PubMed1991

Cerebral-blood-flow-velocity measurements in neonates: technique and interobserver reliability.

The interobserver reliability for absolute cerebral-blood-flow-velocity measurements by colour and duplex Doppler sonography was tested in 32 neonates with a mean birth weight of 1489 (SD 644) g, and a gestational age of 29.9 (SD 3.5) weeks. Using standardized technique, two observers recorded on videotape, the Doppler spectrum of the anterior cerebral artery, the intracranial internal carotid artery and the middle cerebral artery. Peak systolic flow, end diastolic flow, mean flow velocity, resistive index and pulsatility index were computed from 3 consecutive waveforms by each observer. The estimates of interobserver reliability using the intraclass correlation coefficient of the examiners varied from 0.95 to 1.00. Therefore, cerebral blood flow velocity can be reliably measured in premature infants.

Blood Flow Velocity↗
PubMed1991

Prediction of lethal pulmonary hypoplasia and chorioamnionitis by assessment of fetal breathing.

Twenty-three pregnancies with fetuses at risk for pulmonary hypoplasia were studied weekly until delivery. The amount of time spent in fetal breathing activity was recorded under controlled conditions during 1 h using real-time ultrasound. An amniotic fluid index was determined. The clinicians and the pathologist were unaware of the ultrasound findings. Eight of 23 fetuses did not breathe at the last ultrasound examination. Three babies died of pulmonary hypoplasia and two of these showed fetal breathing before birth. The three deaths were associated with rupture of the membranes at less than or equal to 20 weeks gestation and of greater than or equal to 44 days duration. One infant developed bronchopulmonary dysplasia. The amniotic fluid index in these four pregnancies was low and the newborn infants had limb contractures. Chorioamnionitis/funisitis was noted in 13 placentas. Eight fetuses were assessed for fetal breathing within 2 days of birth. The lack of fetal breathing had sensitivity, specificity, positive and negative predictive values of 0.75 for chorioamnionitis/funisitis. In this pilot study the absence of fetal breathing was of no value in predicting lethal pulmonary hypoplasia, but was related to chorioamnionitis/funisitis. We recommend further studies of fetal breathing in relation to fetal/neonatal infections.

Chorioamnionitis↗
PubMed1991

The effect of aminophylline on the excursions of the diaphragm in preterm neonates. A randomized double-blind controlled study.

Aminophylline is used to treat apnoea and to facilitate weaning from assisted ventilation in preterm infants. Aminophylline is thought to increase respiratory drive centrally. We performed a randomized controlled double-blind study to determine if aminophylline increases the excursions of the diaphragm indicating a possible direct peripheral effect. Twenty-two neonates were randomized to treatment with intravenous aminophylline (n = 11) or to no treatment (n = 11). An ultrasonographer, who was blinded to the group assignment, studied the diaphragmatic excursions using a real time sector scanner. The posterior one-third of the right hemidiaphragm was localized and M-mode was used to record the diaphragmatic excursions on paper. The neonates were studied in an awake but quiet state. Aminophylline resulted in an increase (43%) in the excursions of the diaphragm (p = 0.012) with no change in respiratory rate or pCO2. These findings indicate that aminophylline had a measurable effect on the diaphragmatic motion. Further studies combining this technique with other techniques are needed to determine if the main effect of aminophylline in the prevention of apnoea is mainly central or peripheral.

Aminophylline↗
PubMed1989

Prenatal sonographic diagnosis of hepatic hemangioendothelioma with secondary nonimmune hydrops fetalis.

A case of fetal hepatic hemangioendothelioma with secondary nonimmune hydrops fetalis is presented. The prenatal diagnosis, made at 27 weeks' gestation by real-time ultrasonography and pulsed Doppler ultrasound, was confirmed by angiography and pulsed Doppler ultrasound, was confirmed by angiography and autopsy after the infant was born 2 weeks later. To the best of our knowledge, this is the first report of prenatal diagnosis of such an entity.

Adult↗