[Transcutaneous partial pressure measurement].
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Blood Gas Monitoring, Transcutaneous↗
Biomedical subjects
R Huch
Publications and source records attributed to R Huch.
Uteroplacental blood flow velocity waveforms as a predictor of adverse fetal outcome and pregnancy-induced hypertension.
The resistance index (RI) of uteroplacental blood flow velocity waveforms (VWF) was investigated by continuous Doppler ultrasound in 286 nonselected pregnant women with singleton pregnancies at 18-21 weeks (n = 129) and at 31-33 weeks (n = 157) of gestation to evaluate the validity of this method as a screening procedure for abnormal pregnancy outcome (intrauterine growth retardation, pregnancy-induced hypertension and fetal asphyxia). The sensitivity of predicting pregnancy outcome was 26.6% at 18-21 weeks and 17.6% at 31-33 weeks of gestation. It was concluded that this method is too insensitive as a screening tool for the prediction of intrauterine growth retardation and pregnancy-induced hypertension in a low-risk nonselected pregnant population.
Blood Flow Velocity↗
Peripheral skin temperature and microcirculatory reactivity during pregnancy. A study with thermography.
The aim of the study was to compare gradients of skin surface temperature on the arm and hand and to evaluate differences in the skin microcirculation reactivity between pregnant and non-pregnant women. We used the prototype of a highly sensitive thermograph system for the measurements. Eight healthy, non-pregnant women (mean age 27.9 years) and eleven pregnant women in the 14th-40th gestational week with normal pregnancies (mean age 28.7 years) were examined. Compared with the control collective, there were the following differences found in the pregnant group: --Skin temperature (ST) difference from the hand to the forearm was 2.6 +/- 0.8 degrees C instead of 0.6 +/- 1.2 degrees C (p less than or equal to 0.01). --There was a higher ST in the hand (p less than or equal to 0.01), but not in the proximal forearm. --An increase of the ST in the hand and the occurrence of a temperature difference compared with the forearm could be seen even in the early stages of pregnancy. --The skin temperature decrease was less marked in pregnant than in non-pregnant women after application of a cold stimulus (p less than or equal to 0.01) and after venous occlusion (not significant). The results obtained by telethermography indicate that during pregnancy there is a greater increase in the arteriovenous shunt blood flow (represented especially in the skin of the acral regions) than in capillary perfusion (represented mainly in the skin of the trunk and proximal extremities).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Effect of epidural anesthesia for cesarean delivery on maternal femoral arterial and venous, uteroplacental, and umbilical blood flow velocities and waveforms.
The effect of epidural anesthesia on the maternal femoral arterial and venous, uteroplacental, and umbilical circulations was studied by the pulsed Doppler technique in 13 women undergoing elective cesarean delivery. Resistance and pulsatility indices of umbilical arterial velocity waveforms did not change with the use of epidural anesthesia. In the uteroplacental circulation, these indices increased in 11 patients, suggesting an increase in resistance. Reduction of sympathetic tone in resistance and capacitance vessels was reflected in the femoral artery by an increase in systolic and end-diastolic velocities, a reversal of the post-systolic backward flow, and an increase in mean velocity. The latter also occurred in the femoral vein. The diameters of these large maternal vessels did not change. This study suggests an impairment in uteroplacental circulation associated with a drop in peripheral vascular resistance and an increase in leg blood flow after epidural anesthesia.
Anesthesia, Epidural↗
Pharmacokinetic studies on fenoterol in maternal and cord blood.
Fenoterol plasma concentrations were measured by radioimmunoassay in 38 pregnant women at different stages of preterm labor and in cord blood. Eight women were treated intravenously until delivery with 1.0 to 4 micrograms/min of fenoterol for periods ranging from 27 hours to 27 days; blood samples were taken at the same time as cord blood. In these women the fenoterol concentrations in cord blood ranged from 18 to 53% of the maternal concentrations. In eight women treated intravenously with 1.2 to 4.0 micrograms/min for 2 to 15 days, the infusion was stopped 1.3 to 38 hours before delivery. In these instances the concentrations in cord blood reached as much as 90% of the maternal, meaning that the rate of elimination from fetal plasma is lower than that from maternal plasma. Five women were treated daily with 20 to 30 mg per os for 3 to 17 days (three of these women had also had intravenous treatment before). The ratio of cord to maternal blood concentrations was higher than in women receiving the drug intravenously, the relative times of sampling being the same. The findings suggest that: (1) the placental transfer of fenoterol is higher than that found in previous studies in humans and animals with tritium-labeled substances; (2) the rate of fenoterol elimination from fetal plasma after intravenous and oral long-term therapy is lower than that from maternal plasma; (3) after oral administration, the ratios of fetal to maternal fenoterol concentrations are higher than after intravenous infusion.
Administration, Oral↗
Determination of the minimum number of cardiac cycles necessary to ensure representative blood flow velocity measurements.
The aim of this study was to determine the minimum number of cardiac cycles necessary over which blood flow velocity representative of the situation (and not unduly influenced by sporadic irregularities). Blood flow was measured by Doppler ultrasound in the adult a. carotis communis, a. femoralis and fetal a. umbilicalis. The coefficients of variation (CV) for the Pulsatility Index (PI), Resistance Index (RI) and Time Average of Space Average Velocities (TASAV) from 10 averaged cycles were compared with the CVs of the respective indices from 2, 3, 4 up to 9 averaged cycles. The number of averaged cycles where the difference between the coefficients of variability became insignificant (Wilcoxon signed rank test) was taken to be the point at which representative values of PI, RI or, respectively, TASAV are assured. For PI evaluation for the a. carotis communis with either the 7 mx or 15 mx calculation program one needs to average over 7 cardiac cycles. Manually determining the maximum frequency curve envelope, 5 cycles are sufficient. Using these same calculation programs for the a. femoralis, 5, 6 and, respectively, 6, cycles are sufficient for representative PI indices; for the umbilical artery, 6, 8 and, respectively, 7 cycles are necessary. For RI, 5 cycles are sufficient in both the a. carotis communis and a. umbilicalis by manual evaluation. For TASAV, a minimum of 3 cycles for the a. carotis communis and of 7 for the a. femoralis are necessary. Thus the number of cardiac cycles which should be averaged is dependent on the vessel being examined, the index being calculated, and the program being used.
Blood Flow Velocity↗
Doppler sonographic evaluation of exercise-induced blood flow velocity and waveform changes in fetal, uteroplacental and large maternal vessels in pregnant women.
The aim of this study was the evaluation by Doppler sonography of blood flow velocity and waveforms in maternal (Femoral artery and vein, carotid artery, uteroplacental) and fetal (Umbilical artery) vessels before and after exercise. Thirteen healthy women with uncomplicated pregnancies (and outcomes) participated in the study between the 36th and 40th gestational week. Each proband underwent 5 exercise tests in a sitting position on a bicycle ergometer with a work load of 100 Watts during 3 minutes. The Doppler measurements were performed with Acuson 128. In the femoral and carotid arteries, peak velocities (systolic and end-diastolic, and for the femoral artery also post-systolic) as well as the mean blood flow velocities were measured. Mean blood flow velocity was also measured in the femoral vein. For the measurements of the arterial diameters, the M-Mode technique, for the femoral vein diameter, the B-Mode technique was used. The uteroplacental and umbilical blood flow waveforms were analysed by the Resistance and Pulsatility Indices. The maternal heart rate as well as systolic and diastolic blood pressures increased after each of the exercise tests. The mean blood flow velocity increased in both the femoral artery and vein while the vessel diameter remained constant. In the carotid artery, however, the velocity remained constant. An analysis of the velocity waveforms for the femoral artery showed in increase in the systolic and end-diastolic velocities as well as a reversal of the post-systolic flow, where the velocity is negative in a state of rest.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[Diagnosis of fetal asphyxia and methods for intrauterine resuscitation].
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Anesthesia, Obstetrical↗
[Doppler velocimetry of the aorta in materno-fetal blood incompatibility].
The underlying pathogenesis of erythroblastosis fetalis is hemolysis of fetal red blood cells mediated by maternal antibodies. The resulting destruction of erythrocytes leads to progressive fetal anemia, and a hypervolemic condition develops in the fetus. The amount of maternal antibodies, real-time ultrasound, amniocentesis and/or cordocentesis can all be used to evaluate the degree of fetal anemia. The work presented here attempts to show that Doppler ultrasound can be used to detect the hypervolemic condition of anemic fetuses. One hundred fifty Doppler examinations were carried out on the aorta in 37 fetuses to evaluate the blood flow velocities and compare these with the fetal hematocrit. For the Doppler analysis, along with bidimensional echography, a Kranzbühler duplex scanner was used. In addition to the usual indices, the ratio of the median velocity to the maximum systolic velocity and an index of resistance using the maximum velocities 1/2 and 2/3 of the way through the cardiac cycle were calculated. Our examinations showed a significant increase in the temporal average of spatial average velocities (TASAV) and in the temporal average of maximum velocities (TAMV or M). The appearance of a spectral window was characteristic and a dicrotism in the curve was often observed. Much experience with the Doppler technique as well as a knowledge of factors influencing the blood flow velocity (caffeine, theine, nicotine, beta-sympathicomimetics) are necessary before attempting an interpretation of Doppler ultrasound results. Although the use of Doppler ultrasound does not yet permit a reduction in the number of invasive examinations, it does allow an improvement in the quality of surveillance of the fetal condition.
Aorta↗
[A new triple probe for simultaneous measurement of transcutaneous oxygen partial pressure in combination with laser Doppler flowmetry and dynamic fluorescence videomicroscopy].
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Adult↗
[Reliability and limitations of pulse oximetry in corrective cyanotic heart surgery].
The aim of this study was to evaluate the agreement between arterial and pulse oximeter saturation values, especially under hypoxemic conditions, and to test the applicability of the method under routine anesthesia conditions. We studied 13 patients (12 children, 1 adult) with congenital cyanotic heart defects; 12 had a surgical correction during nonpulsatile cardiopulmonary bypass and 1 had a palliative operation. Arterial and pulse oximeter measurements were simultaneously taken and compared during induction of anesthesia, surgery, and in some cases during the postoperative period. Pulse oximeter saturation values were recorded by an Ohmeda Biox 3700 pulse oximeter, and the corresponding arterial saturations determined with a CO Oximeter (OSM2 Hemoximeter, Radiometer). The values lay in the range of 43%-100% arterial oxygen saturation. The results were evaluated while taking into account the steady state and non-steady state situations (i.e., when there were rapidly changing pulse oximetric saturation readings and difficulties in coordinating the comparative arterial measurements time-wise), as well as the equipment's internal characterization of the signal quality (High Quality Signal (HQS)/Low Quality Signal (LQS]. The correlation analysis for all comparative measurements, under both steady state and non-steady state conditions, gave a result of r = 0.927. When the comparison was restricted to the measurements in the steady state conditions, r = 0.935 resulted. The pulse oximetry saturation values had a tendency to lie below the corresponding arterial values. The fact that the pulse oximetry values were designated with HQS or LQS was no indication of a better or worse correlation with the arterial value.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Limitations of pulse oximetry.
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Computers↗
Cerebral blood flow velocity waveforms in hydrocephalic fetuses.
Pulsed Doppler recordings of intracranial arterial velocity waveforms were made in 9 hydrocephalic fetuses during the second or third trimesters of pregnancy. Normal, increased, and decreased velocity waveform indices could be measured in these cases, and 1 fetus presented retrograde diastolic flow. Cerebral blood flow patterns of hydrocephalic fetuses seem to differ individually from case to case, presenting no uniform waveform type in late pregnancy. There was no obvious correlation between ventricular dilatation and the type of the velocity waveform.
Cerebral Arteries↗
Blood flow velocity waveforms at late pregnancy and during labor.
608 high-risk pregnancies were monitored by repeated Doppler-examinations of the fetal aortic blood flow. An absent end-diastolic flow pattern was found to reveal fetal growth retardation with 73% sensitivity. The positive predictive value of this finding for prediction of fetal growth retardation combined with intrauterine distress (prevalence in the material 8%) was 85%. In the cases with this flow pattern, the cesarean section rate was 72%, and the mean gestational age at delivery was 34 weeks. Normal labor was not associated with any changes of umbilical arterial flow velocity waveforms, but the diastolic flow of the arcuate arteries was decreased during uterine contractions.
Blood Flow Velocity↗
[Performance training in pregnancy. Report of respiratory and cardiovascular physiologic changes in a pregnant high-performance athlete in comparison with a sample of normal pregnant patients].
Against the background of dramatic changes that took place in the history of sports during the past one hundred years, we are today discussing with regard to the compatibility of sport and pregnancy whether the extent of sports activities before pregnancy contributes to the amount of stress tolerated during pregnancy. Animal experimental studies on the effect of physical stress on the foetus cannot always be transferred to man, and hence recommendations made to pregnant women are often purely empirical. The article reports on the results of an examination of a professional woman athlete during pregnancy: Various maternal circulatory and respiratory parameters were recorded in this primigravida of 25 years of age, who had been regularly active as a competitive runner for 12 years, during the 24th week of pregnancy and from the 28th week of pregnancy onwards, at intervals of 14 days and post partum, at rest and during steady-state load on a bicycle ergometer (6 minutes each at 40 and 70 watts load, respectively) and a step-by-step load increasing every minute by 15 watts until attainment of a maternal heart rate of 150 beats per minute. The results were compared with those in a group of pregnant women who had not been competitive sportswomen. During continued training as per schedule up to the 36th week of pregnancy of the athlete, there was hardly any change in performance, and there was a marked difference against the other women. The pulse at rest was lower by a mean of 30 beats in the athlete during pregnancy, clearly indicating maintenance of the economic cardiac mechanism known to occur in trained persons, which produces a greater cardiac output via an increased stroke volume at a lower heart rate. This difference was impressively demonstrated under different loads. Another example of more economic management of an identical load is also seen, for instance, in the lower oxygen uptake and lower respiratory rate. Even at a maternal heart rate of 150 beats per minute the foetus of the athlete did not show any signs of stress under test conditions. In a measurement "at site" during the 38th week of pregnancy under routine and training conditions with relevant sprints and a maternal heart rate increase to more than 170 beats per minute, however, foetal behaviour displaying bradycardia clearly showed the existence of tolerance limits for foetal supply.(ABSTRACT TRUNCATED AT 400 WORDS)
Adult↗
[Antenatal fetal heart rate with special reference to maternal posture].
Between the 20th and 40th week of pregnancy in 40 normal single-fetus pregnancies, examinations were carried out at regular intervals to determine prospectively the influence of gestation age and maternal posture on fetal heart rate patterns. It could be demonstrated that both fetal maturation as pregnancy progresses and differing maternal postures lead to significant changes in the fetal parameters. Failure to take these influences into consideration can lead to a false assessment of the condition of the fetus.
Electrocardiography↗
Blood flow velocity waveforms in large maternal and uterine vessels throughout pregnancy and postpartum: a longitudinal study using Duplex sonography.
Blood flow velocity waveforms in large maternal and uterine vessels were measured longitudinally from 16 weeks gestation onwards until 12 weeks postpartum in 21 singleton pregnancies by duplex sonography. In the maternal carotid artery, time average mean velocity (TAVmean) did not show significant changes. In both the femoral artery and vein, however, significant changes were observed. In the femoral artery, TAVmean and systolic maximum velocities decreased with advancing gestation. In the femoral vein, TAVmean remained constant throughout pregnancy and was lower than postpartum. The resistance index in the uterine arteries decreased with advancing gestation and increased after delivery. Among many factors contributing to femoral arterial blood flow velocity changes in pregnancy, we suggest that a major one is the increase in uterine blood flow. Reduction in venous femoral blood flow velocity and increase in the femoral vein diameter might be associated with the common occurrence of venous disorders in pregnancy.
Adolescent↗
Normal placental function and fetoplacental blood circulation in advanced abdominal pregnancy.
Normal levels of unconjugated estriol and human placental lactogen hormone in the maternal serum and a normal, reactive pattern of non-stress test cardiotocography were recorded in a case of advanced abdominal pregnancy with surviving newborn. The placenta was inserted at the base and side walls of fossa Douglas. Fetal, umbilical and retroplacental arterial Doppler ultrasound examinations revealed normal velocity waveforms. These findings indicated that the trophoblast invasion to the retroplacental arteries also occurs when the placenta has an extra-uterine insertion, and this can result in a normal placental blood supply and function.
Adult↗