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Biomedical subjects

G Rizzo

Publications and source records attributed to G Rizzo.

At least 199 records · Page 11Linked to original sources
PubMed1990

Functional assessment of uteroplacental and fetal circulations by means of color Doppler ultrasonography.

A study was made in order to assess whether the combined use of color flow mapping and conventional pulsed Doppler could improve the accuracy of blood flow velocity waveform analysis in fetal and placental circulations. Fifty patients were studied at 18 to 20 or 26 to 28 weeks of gestation by two trained investigators by means of either conventional Doppler or conventional Doppler plus color flow mapping. Recordings were performed at the level of the uterine arteries, umbilical artery, descending aorta, and internal carotid artery. The experimental procedure was repeated the following day with the patients undergoing the alternate technique of recording. In all the vascular districts investigated, color flow mapping allowed us to obtain a higher number of reliable recordings, to shorten the observation time, and to reduce the intra- and interobserver coefficient of variations.

Aorta, Thoracic↗
PubMed1989

Plasma protein binding of alpidem in healthy volunteers, in neonates and in liver or renal insufficiency.

The binding of alpidem, a new anxiolytic drug, has been studied in plasma from 6 healthy subjects, 12 patients with renal failure, 12 patients with liver cirrhosis and 12 chronic uraemics maintained on haemodialysis, as well as in 12 serum samples from the placental cord, to represent the situation in the newborn. The unbound fraction was 0.61% (healthy volunteers), 1.31% (newborns), 0.86% (cirrhotic patients), 0.72 (patients with renal failure), 0.70% (before haemodialysis) and 0.79% (after haemodialysis). Binding in the volunteers was significantly different from that in neonates and cirrhotics only. Alpidem became bound to isolated albumin (45 g.l-1) and alpha 1-acid glycoprotein (0.75 g.l-1) to 97.2% and 97.1%, respectively. The bound fraction of the drug in a mixture of two proteins was 99.1%. For alpidem, it appears that alpha 1-acid glycoprotein may balance the effect of any decrease in the albumin concentration.

Adult↗
PubMed1989

Behavioural state transitions in healthy and growth retarded fetuses.

The transitions, i.e. time intervals between two different behavioural states, were studied in 10 healthy and 10 growth retarded fetuses (IUGR) in near term pregnancies. In healthy fetuses, transitions usually lasted less than 3 min whereas IUGR fetuses showed a longer duration when compared to healthy fetuses. Moreover, a significant trend in the change of state variables (fetal heart rate, fetal eye movements and fetal gross body movements) was evident in healthy fetuses: fetal heart rate was the first variable to change in transitions from 1F to 2F and the last variable to change in transitions from 2F to 1F. On the other hand IUGR fetuses showed a random sequence in order of change. These findings were substantiated by the intraindividual consistency evidenced in repeated recordings. In conclusion the analysis of transitions differentiates between healthy fetuses and those affected by IUGR.

Blood Flow Velocity↗
PubMed1989

Are blood flow velocity waveforms related to umbilical cord acid-base status in the human fetus?

Doppler blood flow velocity waveforms from fetal umbilical artery, descending aorta, internal carotid artery and maternal uterine arteries were recorded in 50 fetuses near term undergoing cesarean section before the onset of labor in order to evidence eventual relationships with the fetal acid-base status. The primary indications for cesarean section were in 16 cases an elective repeated cesarean section and in the remaining cases maternal hypertension often associated with fetal growth retardation and/or fetal distress. The technique of anesthesia was strictly standardized and fetal blood gas levels and acid-base status were analyzed in umbilical artery and vein immediately after birth. A significant correlation was found between the pulsatility index from internal carotid artery and the pO2 levels in umbilical vein (r = 0.87; p less than or equal to 0.001). Similar relationships were found between the pulsatility index from descending aorta and the pCO2 (r = 0.78; p less than or equal to 0.001), base excess (r = 0.72; p less than or equal to 0.001) and pH (r = 0.80; p less than or equal to 0.001) levels in umbilical artery. It is suggested that Doppler ultrasound could be useful in the diagnosis of fetal hypoxia and acidosis.

Acid-Base Equilibrium↗
PubMed1989

Hemodynamic changes in growth retarded fetuses during maternal oxygen administration as predictors of fetal outcome.

The changes in fetal hemodynamics during maternal administration of 60% humidified oxygen were assessed by Doppler ultrasonography in 15 growth retarded fetuses characterized by abnormal blood flow velocity waveforms. During oxygen treatment, nine fetuses exhibited temporary hemodynamic modifications as expressed by a recovery toward the normal range of vascular impedance in the descending aorta and internal carotid artery, whereas no changes were found in the remaining six fetuses. In this latter group, a rapid deterioration of fetal condition occurred and all the fetuses were delivered by emergency cesarean section within 9 days from the Doppler examination. The absence of recovery of vascular resistance during acute maternal oxygen administration seems therefore to be a useful marker of imminent acute distress in fetuses with growth retardation secondary to chronic hypoxia.

Blood Flow Velocity↗
PubMed1989

Prenatal cerebral Doppler ultrasonography and neonatal neurologic outcome.

The significance of fetal cerebral blood flow analysis in the prediction of neonatal neurologic outcome was investigated on 87 fetuses at risk for chronic hypoxia. Blood flow velocity waveforms were recorded from the fetal internal carotid artery immediately before cesarean section; newborns underwent neurologic follow-up until discharged from the neonatal division. Neonatal outcome was considered abnormal in presence of a postasphyxial encephalopathy. Receiver operating characteristic curves were used to demonstrate the efficacy of fetal cerebral blood flow velocity waveform analysis as a predictor of neonatal outcome. A value of the pulsatility index from the internal carotid artery below the second standard deviation of our range of normality was found to be a powerful indicator of the development of neonatal neurologic abnormalities (Cohen's Kappa index = .58). These results were particularly evident in fetuses with a birthweight above 2500 g in which a specificity of 93.7%, a sensitivity of 75%, and an accuracy of 89.7% were achieved.

Central Nervous System Diseases↗
PubMed1989

Plasma protein binding of ethinyloestradiol: effect of disease and interaction with drugs.

The protein binding of ethinyloestradiol (EE2) was investigated in the plasma from 14 healthy volunteers, 10 patients with hyperbilirubinemia, 10 patients with liver cirrhosis and 10 patients with renal failure. Binding assay was performed by equilibrium dialysis at 37 degrees C. The unbound fraction (mean +/- SD) of EE2 was 1.17 +/- 0.12 (volunteers), 2.74 +/- 0.77 (hyperbilirubinemics; p less than 0.001) 1.51 +/- 0.31 (cirrhotics; p less than 0.01) and 1.44 +/- 0.11 (renal failure; p less than 0.001). Studies with isolated albumin and alpha-1-acid glycoprotein showed that albumin is the major plasma protein to bind EE2. Warfarin (75 microM) and diazepam (75 microM) increased by 5.0% and 3.0%, respectively, the unbound fraction of EE2 when albumin concentration was 15 microM. Under similar conditions, digitoxin did not modify the binding of EE2. At therapeutic concentrations, warfarin and diazepam did not affect the binding of EE2 in plasma.

Adult↗
PubMed1988

Computer-assisted analysis of fetal behavioural states.

A computerized system which simultaneously acquires and quantifies several ultrasonically detected fetal activities, including gross body movements, breathing movements, and eye movements, was developed in order to obtain additional quantitative data on fetal behaviour. Movements were automatically related to fetal heart rate allowing computation of their mean incidence, duration, lag time and percentage time spent moving during different heart rate patterns. The incidence of various behavioural states was also calculated. The study of 15 healthy fetuses near term revealed the existence of statistically significant differences in these parameters between low and high variability patterns of fetal heart rate suggesting a quantitative modulation of fetal movements by behavioural states.

Computer Graphics↗
PubMed1988

Short-term effects of maternal oxygen administration on blood flow velocity waveforms in healthy and growth-retarded fetuses.

To determine whether maternal oxygen administration affects fetal hemodynamics, we investigated 10 healthy fetuses and 10 growth-retarded fetuses near term by means of Doppler ultrasonography. The growth-retarded fetuses were characterized by abnormal blood flow velocity waveforms. Velocity waveforms were simultaneously recorded at 5-minute intervals from the fetal descending aorta and internal carotid artery before, during, and after maternal oxygen administered through a face mask that delivered 60% oxygen. The pulsatility index was calculated. During oxygen treatment growth-retarded fetuses showed significant temporary hemodynamic modifications as expressed by changes of pulsatility index values that increased in the internal carotid artery and decreased at the level of the descending aorta. On the other side no changes were found in healthy fetuses. These findings suggest that maternal oxygen administration can modify fetal hemodynamics in cases of growth retardation associated with abnormal blood flow velocity waveforms.

Analysis of Variance↗
PubMed1988

Parameter extraction from heart rate and arterial blood pressure variability signals in dogs for the validation of a physiological model.

The paper describes an automatic procedure for improving the extraction of parameters in heart rate (HR) and arterial blood pressure (ABP) beat-to-beat variability signals. Auto- and cross-spectral analysis of such signals is carried out through parametric models and the distribution of the power of the spectra and the phase relationships are compared in various physiological situations induced in the dogs via drug infusion or surgical interventions which do influence the control mechanisms of HR and ABP. This "black-box" approach allows the obtention, directly from the processing of the above-mentioned signals, of the estimation of parameters relative to cardiovascular models, as the ones described by simple equations (Windkessel and Starling laws are introduced as examples). These parameters seem to validate significantly the capability of such models to describe the physiological interactions existing between the two considered signals. Applications may be foreseen both for research and clinical purposes.

Algorithms↗
PubMed1988

Doppler echocardiographic assessment of atrioventricular velocity waveforms in normal and small-for-gestational-age fetuses.

A prospective longitudinal study determined the physiological patterns of blood flow velocity waveforms in normal and in small-for-gestational-age (SGA) fetuses. Using a Pulsed Doppler Duplex system, 125 normally grown fetuses and 35 SGA fetuses were studied longitudinally at between 27 and 42 weeks gestation. In normal fetuses the ratio between the E velocity (early passive ventricular filling) and the A velocity (active ventricular filling during atrial contraction) increased progressively during pregnancy in both transmitral and transtricuspid waveforms, approaching 1 at term. In SGA fetuses, the E/A ratios did not increase during pregnancy and the values obtained were significantly lower than in normal fetuses. The ratio between the transtricuspid and transmitral mean temporal velocities remained almost constant throughout pregnancy in the normal fetuses with transtricuspid velocity slightly exceeding the transmitral velocity. On the other hand, in SGA fetuses the ratio between the mean temporal velocities was inversed with the transmitral velocity progressively greater than the transtricuspid velocity suggesting the existence of intracardiac haemodynamic changes in these fetuses.

Blood Flow Velocity↗
PubMed1988

Differential diagnosis of small-for-gestational age fetuses by Doppler ultrasound.

The purpose of this investigation was to compare the efficacy of conventional ultrasonographic measurements (i.e. head to abdomen circumference ratio, amount of amniotic fluid) with Doppler ultrasonography in the differential diagnosis of small-for-gestational age (SGA) fetuses. Blood flow velocity waveforms were recorded from the umbilical artery descending aorta and internal carotid artery in 121 intrauterine growth-retarded fetuses and the pulsatility index was evaluated as an index of vascular impedance. Conventional ultrasonographic measurements were of limited usefulness in the differential diagnosis, whereas the ratio between the pulsatility indexes from umbilical and carotid arteries proved to be a good index for discriminating SGA fetuses due to low growth potential (congenital infections, structural anomalies, chromosomal abnormalities, constitutional factors) from those caused by placental dysfunction (specificity 96.6%, sensitivity 89%, positive predictive value 98.7%, negative predictive value 74.3% and accuracy 90.9%.

Amniotic Fluid↗
PubMed1988

Computerized analysis of behavioural states in asymmetrical growth retarded fetuses.

The fetal behaviour of 15 asymmetrical intrauterine growth retarded (IUGR) fetuses was compared to that of a control group of healthy fetuses. Fetuses underwent simultaneous cardiotocographic and ultrasonographic examinations for 2 consecutive hours at 36-38 weeks' gestation. Behavioural states analysis was carried out by means of a computerized system (Digital PDP 11) that allowed the recording of several fetal variables including heart rate (FHR), gross body movements (FM), eye movements (FEM) and breathing movements (FBM). FHR was classified in four different patterns (FHRP) according to Nijhuis et al.; fetal movements were automatically synchronized with FHR and grouped for each FHRP. Several quantitative parameters (i.e. incidence, mean duration, lag time, % time spent moving) were then computed for each movement. There were no statistical differences in the distribution of FHRP between healthy and IUGR fetuses. On the other hand quantitative differences were found when the movements investigated were related to FHRP. In IUGR fetuses FEM were mainly represented by low frequency movements (IEM) during both low (FHRP A) and high variability (FHRP B) FHRP, whereas healthy fetuses exhibited mostly rapid eye movements (REM) during FHRP B and absent type of FEM during FHRP A. Moreover IUGR fetuses showed a reduction of state 1F (quiet sleep) and an increase of periods of no coincidence between behavioural state variable when compared to the control group fetuses. These findings, therefore suggest the existence of quantitative differences in fetal behaviour in asymmetrical IUGR fetuses when compared to healthy fetuses.

Cardiotocography↗