Biomedical subjects

R L Deter

Publications and source records attributed to R L Deter.

At least 55 records · Page 3Linked to original sources

PubMed1989

Individual growth curve standards for fetal head and abdominal circumferences: effect of the type of measurement on growth prediction.

Head and abdominal circumferences (HC, AC) can be measured directly or estimated from diameters. Accurate prediction of circumference growth after 26 weeks depends on growth model specification and the quality of the circumference measurement method used. To evaluate the effect of the method of measurement, direct and estimated HC and AC values from 20 normal fetuses, obtained between 15 and 38 weeks, were used to determine two pairs of functions for specifying HC and AC growth models. The two HC and AC data sets and pairs of model specification functions were used in various combinations to determine HC and AC growth models, to predict growth after 26 weeks, and to compare predicted values to actual measurements. Systematic and random prediction errors were determined for each combination. For HC no differences in either type of error were found. Similar results were obtained for AC with one exception, a statistically significant difference in systematic error between the directly measured circumferences - model specification based on estimated values combination and the estimated circumferences - model specification based on directly measured values combination. These results indicate that the prediction of future HC and AC growth is not significantly affected by the type of circumference measurement procedure used except in extreme cases where circumference measurements are made on parts of the body that can be easily distorted.

Abdomen↗

PubMed1989

Development of individual growth standards for estimated fetal weight: II. Weight prediction during the third trimester and at birth.

Using a weight estimation procedure based of the Rossavik growth model, we have evaluated the possibility of establishing individual growth curve standards for fetal weight estimates and of predicting birth weights in the second trimester. In 20 normal fetuses delivered at term, 95% of the weight estimates obtained after 26 weeks' menstrual age (MA) were within +/- 22% of the predicted weight estimates. In these same fetuses the mean difference between birth weight estimates based on growth patterns before 26 weeks, MA, and actual birth weights was 1.2%, with 95% of the percent deviations being between 13.3% and - 8.8%. In a similar prospective study, the mean percent difference was -1.7%, with a range of 9.6% to -13.6%. Direct comparison of weight estimates obtained during the last week before delivery with birth weight projections indicated that birth weight estimates obtained 14 weeks before delivery had smaller systematic and random errors than those obtained within a week of delivery. These results indicate that individual growth curve standards for fetal weight estimates and the growth potential of individual fetuses can be determined from growth patterns in the second trimester.

Birth Weight↗

PubMed1989

Predicting the birth characteristics of normal fetuses 14 weeks before delivery.

This investigation has evaluated the ability of Rossavik growth models (derived from data obtained before 26 weeks) to predict birth characteristics in normal fetuses (assuming no growth after 38 weeks). Both weight and head circumference were predicted without systematic errors and the ranges of the random errors were approximately +/- 10% and +/- 5%, respectively. A range of approximately +/- 10% for the random error was also found for the abdominal and thigh circumferences, but both parameters were systematically overestimated (17.3% and 6.4%, respectively). No evidence of a relationship between the percent deviation and age at delivery (up to 41 weeks) was found for any of the parameters studied. As indicators of pregnancy outcome, Growth Potential Realization Index (GPRI) values were calculated for each parameter (predicted values corrected for systematic errors were used for the abdominal and thigh circumferences). Mean GPRI values were not significantly different from 100% and the ranges were approximately 90% to 110% except for the head circumference (range: 95% to 105%). These results indicate that GPRI values can be used to characterize the outcome of prenatal growth processes on an individual basis, with each fetus acting as its own control.

Adult↗

PubMed1989

Prediction of normal fetal growth by the Rossavik growth model using two scans before 27 weeks, menstrual age.

Individual growth curve standards for five fetal anatomic parameters (head and abdominal circumferences, head and abdominal cubes, and femur diaphysis length) and estimated fetal weight were prospectively developed in 70 pregnant women who delivered infants with growth considered appropriate-for-menstrual age. For this purpose, we used the Rossavik growth model (P = c(t) kappa + s(t], model specification functions previously reported, and the data of two scans before 27.0 weeks of menstrual age, separated by an interval of at least 5 weeks. The anatomic parameters and estimated weights of these fetuses in the last 14 weeks of gestation were found to have values close to their projected standards. Whereas there was a significant, although small, systematic error of overprediction for most of the parameters and estimated fetal weight, deviations between observed and expected values were, with few exceptions, within the ranges established by Deter for normal growth. This study demonstrates that the Rossavik growth model could be used to predict normal fetal growth in a sample of patients different from those from which the model was developed.

Anthropometry↗

PubMed1989

Influence of the interval between time points on individual fetal growth curve standards derived from Rossavik models and two ultrasound scans before 26 weeks, menstrual age.

We studied the influence of the interval between the two scans used before 26 weeks' menstrual age to generate individual fetal growth curve standards utilizing the Rossavik growth model: P = c(t) kappa + s(t) (model specification functions previously reported). Intervals of 3 weeks to 12 weeks were suitable for predicting the growth of the abdominal and head circumferences and femur diaphysis length in individual fetuses. However, large systematic and random errors were found with intervals less than 5 weeks for three-dimensional parameters such as the head and abdominal cubes and estimated fetal weight. In addition, the data suggest that the systematic errors for these latter parameters may increase with intervals of 10 weeks or more. Overall, optimal individual fetal growth curve standards were best generated from two scans before 26 weeks' menstrual age separated by 5 weeks to 9 weeks.

Anthropometry↗

PubMed1989

Effect of timing of initial scan and interval between scans on Rossavik growth model specification.

The effect of the time of the initial scan and the interval between the two scans needed for Rossavik growth model specification was evaluated in 20 normally growing fetuses. Based on systematic and random prediction errors, determined by comparing predicted values to measured values obtained after 27 weeks, menstrual age, optimal results for all parameters studied were obtained with an initial scan at 18 weeks and an interval of 6 weeks between scans. For one-dimensional parameters--head circumference (HC), abdominal circumference (AC), and femur diaphysis length (FDL)--similar results were obtained with an initial scan at 15 weeks and an interval of 3 weeks, but systematic overestimations were seen with 9-week intervals for HC. Studies with three-dimensional parameters--head cube, abdominal cube, and estimated weight--indicated that the timing of the initial scan was not critical, although less variability was seen with the initial scan at 18 weeks. However, the use of 3-week and 9-week intervals (instead of 6 weeks) produced significant systematic errors that varied with the parameter studied. These results suggest that Rossavik growth model specification is possible under a variety of conditions, but both the timing of the initial scan and the interval between scans must considered for each parameter.

Embryonic and Fetal Development↗

PubMed1989

Individual growth curve standards in twins: prediction of third-trimester growth and birth characteristics.

The ability of Rossavik growth models, determined from measurements obtained before 24 weeks, to predict third-trimester growth and birth characteristics in normally growing twins has been investigated. Third-trimester values for head circumference, abdominal circumference, and femur diaphysis length were predicted with an accuracy of +/- 6% to 9% (95% to 98% of percent deviations). For thigh circumference and estimated weight, the comparable values were +/- 15% and +/- 16%, respectively. The head circumference at birth was predicted without bias; the random error was approximately +/- 5% (94% of percent differences). Weight, abdominal circumference, and thigh circumference were systematically overestimated (3.1%, 14.9%, and 11.3%, respectively) as a result of differences in prenatal and postnatal measurement procedures. After correction for systematic errors, these parameters could be predicted with random errors of -11.5% to 7.2% (weight), -12.8% to 5.4% (abdominal circumference), and -15.3% to 10.0% (thigh circumference). Growth Potential Realization Index values were found to have means of approximately 100% and ranges from 91% to 118%. These results are similar to those for singletons and indicate that individual assessment of growth in twins can be carried out with the same methods used for singletons.

Adult↗

PubMed1989

Doppler assessment of the pulsatility index of the middle cerebral artery during constriction of the fetal ductus arteriosus after indomethacin therapy.

To investigate the effects of constriction of the ductus arteriosus on the pulsatility index of the middle cerebral artery, maximum velocity waveforms were obtained in 13 fetuses (one set of twins) whose mothers were treated with indomethacin for preterm labor (n = 9) or polyhydramnios (n = 3). Eleven of the fetuses manifested ductal constriction within 48 hours of therapy, whereas two fetuses had constriction after 1 week of therapy. Six of the 13 fetuses also manifested tricuspid insufficiency in association with constriction of the ductus arteriosus. All abnormal cardiac changes resolved in utero after discontinuation of indomethacin. No difference in the pulsatility index values of the middle cerebral artery was observed in the fetuses with ductal constriction but without tricuspid regurgitation (n = 7) when the values were compared with those obtained in absence of ductal constriction (1.87 +/- 0.37 vs. 1.88 +/- 0.33). In the fetuses that manifested both ductal constriction and tricuspid insufficiency (n = 6), the pulsatility index values in the middle cerebral artery were significantly lower in the presence of ductal constriction when compared with the values obtained in the absence of ductal constriction (2.22 +/- 0.26 vs. 1.57 +/- 0.34). These results indicate that a response to indomethacin sufficient to cause both ductal constriction and tricuspid insufficiency decreases the pulsatility index of the middle cerebral artery.

Blood Circulation↗

PubMed1989

Doppler assessment of the pulsatility index in the cerebral circulation of the human fetus.

To determine whether the pulsatility index was similar in all cerebral vessels, 30 fetuses at 23 to 37 weeks' gestation were studied. There were 12 normal fetuses, 14 growth-retarded fetuses, and 4 fetuses that were transfused in utero because of Rh isoimmunization. The middle cerebral artery and the internal carotid artery were studied in all fetuses. The proximal anterior cerebral artery was also studied in addition to the other two vessels in 12 fetuses from the three groups. The pulsatility index was significantly higher in the middle cerebral artery than in the internal carotid artery in all three groups. The pulsatility index of the proximal anterior cerebral artery was between the values shown for the middle cerebral artery and the internal carotid artery. The pulsatility index of the proximal anterior cerebral artery was significantly different from the index for the middle cerebral artery and not significantly different from the index for the internal carotid artery. These data indicate the importance of knowing exactly which cerebral vessel is being insonated, so that the Doppler waveform can be interpreted correctly.

Carotid Artery, Internal↗

PubMed1989

Comparison of four types of intrauterine transfusion: effect on fetal hematocrit.

The advent of cordocentesis has made it possible to treat fetuses affected by severe red cell alloimmunization by infusing red cells into umbilical vessels. In addition, serial hematocrits can be followed between transfusions. Twenty fetuses underwent a total of 118 intrauterine procedures. Four transfusion techniques were compared to assess the effect of each method on the stability of the fetal hematocrit between procedures. The change in hematocrit per day for direct intravascular transfusion was -1.06 +/- 0.68%, for intraperitoneal transfusion: +0.03 +/- 0.6%, for combined exchange intravascular and intraperitoneal transfusion: +0.02 +/- 0.3% and for combined direct intravascular and intraperitoneal technique: -0.01 +/- 0.4%. The greatest fall in hematocrit was noted with the use of the direct intravascular technique alone (p less than 0.001). The combined direct intravascular/intraperitoneal approach produces a stable hematocrit between procedures and offers the possibility of performing intrauterine transfusions at less frequent intervals.

Blood Transfusion, Intrauterine↗

PubMed1989

Intravenous pancuronium bromide for fetal neuromuscular blockade during intrauterine transfusion for red-cell alloimmunization.

Intravenous pancuronium bromide was administered into the umbilical cord by funipuncture to effect temporary fetal paralysis. Neuromuscular blockade was achieved in 12 fetuses undergoing a total of 34 intrauterine procedures for the treatment of severe red-cell alloimmunization. The same initial dose of 0.2 mg/kg fetal weight estimated by ultrasound was used in all cases, but anemic fetuses did not resume movement for prolonged periods. A relationship among fetal hematocrit, adjusted dose, and duration of paralysis was described by the equation: Duration (hours) = 5.24 + 10.30 adjusted dose (mg/kg) - 0.16 hematocrit (%) (R2 = 0.49; P less than .001). Intravenous pancuronium was found to be a safe and effective method for cessation of fetal movement during intrauterine procedures.

Blood Transfusion, Intrauterine↗

PubMed1988

Mathematical modeling of fetal growth: V. Fetal weight changes at term.

Fetal growth after 37 weeks menstrual age was investigated by comparing ultrasound estimates of fetal weight with corresponding weights of newborns. Using a weight estimation equation with minimal systematic error, evidence was found that fetuses delivered at term do not increase in weight the last two weeks before delivery. This change in fetal growth is regarded as a biological process that is needed to prepare the fetus for its life after birth. Only one of three subsets, that of estimated weights below 3000 g, showed significant weight increase after 37 weeks. This subset had, however, on average the longest scan-delivery interval. We conclude that conventional birthweight standards are influenced both by a cessation of fetal growth approximately two weeks before delivery and by an association between fetal size and the duration of gestation.

Birth Weight↗

PubMed1988

Development of individual growth curve standards for estimated fetal weight: I. Weight estimation procedure.

In this investigation the weight estimation procedure of Rossavik was reassessed with particular emphasis on parameter estimation and performance over a wide weight range. Using a cross-sectional data set (193 patients), a longitudinal data set (20 patients), and an iterative procedure, parameter estimates were obtained based solely on regression analysis. Comparison of weight estimates obtained using a function based on these parameter values with actual birth weights indicated virtually no systematic errors over a 250-g to 4750-g weight range and random errors (+/- 1 SD) of 10% to 13% below 200 g and 6% to 8% above 2000 g. The weights of small- and large-for-gestational age fetuses were systematically overestimated (4.1%) and underestimated (-3.0%), respectively, but systematic errors were not found in average-for-gestational age fetuses. No differences in random errors were seen in these three growth categories. Comparison with other weight estimation procedures indicated that the Rossavik procedure gives weight estimates that are at least as accurate as those obtained with other methods over a wide range of weight and growth categories. However, the Rossavik procedure can be used to generate individual growth curve standards for weight estimates, a characteristic not shared with other weight estimation procedures.

Birth Weight↗

PubMed1987

Mathematical modeling of fetal growth. III. Evaluation of head growth using the head profile area.

Growth of the fetal head has been reexamined in a longitudinal study of 32 normally growing fetuses using the head profile area (HA). The Rossavik growth model (characterized by the coefficients c, k, and s) fit these data very well (R2 [+/- SD] 99.6 [+/- 0.3]%), and regression analysis indicated that optimum results are obtained when the coefficient k is kept constant. Head area growth before 28 weeks was found to be related to the coefficient c, which was strongly correlated (R2 69.2%) with the time of HA growth initiation. These results suggest that c reflects the genetic factors controlling growth in the early part of pregnancy. The coefficient s was negatively correlated with c (R2 82.1%) and had two components, one associated with c (pred. s) and one not associated with c (s-residual). This linkage between c and s, together with the parallel head growth seen after 30 weeks, suggests the possibility of a maternal system in which genetically determined head size (c) can be sensed and modified by other factors (s) to maximize compatibility between the fetal head and maternal pelvis.

Birth Weight↗

PubMed1987

Mathematical modeling of fetal growth. IV. Evaluation of trunk growth using the abdominal profile area.

Growth of the fetal abdomen has been reexamined in a longitudinal study of 32 normally growing fetuses using the abdominal profile area (AA) and the Rossavik growth model. The growth of the fetal abdomen was compared to that of the fetal head. In early pregnancy the growth rate was higher for the fetal head than for the fetal abdomen, whereas the opposite was the case in late pregnancy. The coefficient k was lower, and the s was higher, for AA than for the head profile area (HA), giving a less prominent sigmoid shape to the AA growth curve. The best correlation to fetal weight at birth was found for the AA growth curve as a whole. The AA s-residual correlated best of all single parameters, with the coefficient c of HA being next. The s-residual appears to reflect the nutritional supply available in late pregnancy, and we conclude that fetal weight at birth depends more on this supply than on the genetic factors controlling fetal growth.

Abdomen↗

PubMed1987

Longitudinal studies of femur growth in normal fetuses.

As an indicator of fetal limb growth, change in the femur diaphysis length (FDL) between 15 and 38 weeks, menstrual age, has been evaluated in a longitudinal study of 20 normal fetuses, as determined by prenatal biparietal diameter, head circumference, and abdominal circumference growth patterns as well as postnatal pediatric assessment. Individual FDL growth curves were uniformly parabolic and followed very similar trajectories. The projected start points [mean: 9.7 (+/- 1.5 SD) weeks] for these curves were in complete agreement with embryologic data, and the curves themselves were well characterized by the Rossavik model [R2 99.5 (+/- 0.5 SD)%]. No differences between males and females were detected, and good agreement was obtained between the average longitudinal growth curve and the cross-sectional growth curve derived from a previously studied data set. Individual growth curve standards, determined from Rossavik models based on data obtained before 26.1 weeks, menstrual age, were within 7% of actual measurements in 94% of the 97 time points studied after 26 weeks. These results indicate that the Rossavik model and its associated individual growth curve standards can be used to evaluate the growth of the femur and thus provide an improved means for detecting skeletal dysplasias and fetal growth retardation.

Adult↗

PubMed1987

The use of fetal neuromuscular blockade during intrauterine procedures.

Advances in fetal therapy have led to the utilization of such techniques as intravascular transfusion of the Rh-affected fetus, bladder shunt placement in the fetus with obstructive uropathy, and percutaneous umbilical blood sampling. Fetal movement makes these procedures technically more difficult while increasing the risk of fetal injury. However, maternal sedation rarely results in adequate suppression of fetal activity. Thus we tested the sedative effects of intramuscular d-tubocurarine (3 or 1.5 mg/kg) or pancuronium bromide (0.3 mg/kg) injected into the fetal gluteal region under ultrasound guidance in conjunction with 70 invasive in utero procedures. Short-term paralysis of the fetus was induced in all cases. No deleterious effects of this technique were noted on initial examination of the neonates. Neuromuscular blockade was found to be a very useful adjunct to both diagnostic and therapeutic procedures involving the fetus.

Adult↗

PubMed1987

Umbilical cord hematoma secondary to in utero intravascular transfusion for Rh isoimmunization.

Direct intravascular transfusion of the fetus with Rhesus isoimmunization is becoming more widespread as the procedure of choice in the treatment of this disease. To date no direct complications of this new procedure have been reported. The authors describe a case of cord hematoma with resulting fetal compromise secondary to venipuncture of the umbilical vein. Doppler studies and review of the fetal heart rate tracings pointed toward umbilical artery vasospasm secondary to the cord hematoma as the etiology of the transient fetal bradycardia.

Adult↗