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I K Rossavik

Publications and source records attributed to I K Rossavik.

At least 19 recordsLinked to original sources
PubMed1993

Macrosomatia and ultrasonography: what is the problem?

It has been claimed that sonographic techniques offer no advantages over palpation of the maternal abdomen for detection of macrosomatia. We studied a group of 498 pregnant patients, 36 (7.2%) of whom gave birth to infants having macrosomatia. A sensitivity of 67%, specificity of 97%, and positive predictive value of 67% was obtained using our method without significant systematic error. Three problems that could reduce the value of ultrasonography in the detection of macrosomatia were detected: (1) use of equations with systematic errors; (2) human bias; and (3) use of ultrasonography machines/transducers with insufficient capacity.

Anthropometry↗
PubMed1992

Understanding the different phases of fetal growth.

Fetal growth was studied in 78 newborns who had serial scans in pregnancy. Weight at birth correlated with growth in the first 2 trimesters but better with the growth between 28 and 32 weeks. The correlations for weight at growth cessation were better than those for weight at birth. Crown-heel length at cessation did not correlate with fetal growth in the first 2 trimesters. Maternal weight increase correlated with fetal weight and crown-heel length but not with head circumference at cessation. Maternal prepregnancy weight correlated with fetal growth between 28 and 32 weeks, but not with fetal growth in the second trimester. A negative correlation was found between estimated duration of growth cessation and relative head circumference at birth.

Birth Weight↗
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

Conceptional age, menstrual age, and ultrasound age: a second-trimester comparison of pregnancies of known conception date with pregnancies dated from the last menstrual period.

Ultrasound dating-curve analysis was performed for the biparietal diameter, mean head diameter, and mean trunk diameter in individual singletons, twins, and triplets from in vitro fertilization (IVF) pregnancies and pregnancies with ultrasonographic determination of ovulation. Linear growth was found for all parameters prior to 28 weeks' conceptional age. No differences were observed among singletons, twins, or triplets. Using linear equations, no significant difference was found in systematic errors between pregnancies with a known date of conception and pregnancies dated from the last menstrual period (LMP). Pregnancies with reliable LMPs had only a slight and nonsignificant increase in random errors when compared with pregnancies from IVF. Current polynomial dating equations produced considerable systematic and random errors as well as errors related to fetal growth. Acceptable results were obtained with a new linear equation based on two examinations. We conclude that gestational age based on good menstrual records supported by a pelvic examination in the first trimester may be more reliable than even the best ultrasound method for dating.

Embryonic and Fetal Development↗
PubMed1989

Implications of sino-aortic baroreceptor reflex dysfunction in severe preeclampsia.

Loss of sino-aortic baroreceptor reflex sensitivity has been associated with various forms of hypertension. Baroreflexive dysfunction antedates elevation of blood pressure (BP) in some forms of hypertension, and may play a role in their pathogenesis. We studied baroreflex function in seven women with severe preeclampsia being treated with intravenous hydralazine. As indices of baroreflex sensitivity and hemodynamic competence, we measured the reflexive elevations in heart rate (HR) (delta HR/delta BP) and cardiac index (CI) (delta CI/delta BP) in response to hydralazine-induced falls in blood pressure. The change in cardiac index per unit change in systemic vascular resistance index (SVRI) (delta CI/delta SVRI) served as an additional measure of hemodynamic competence. The results indicated that a higher baseline blood pressure was associated with a dramatic reduction in baroreflex sensitivity (delta HR/delta BP) and baroreflex control of blood pressure (delta CI/delta BP and delta CI/delta SVRI). In patients with higher baseline blood pressures, the severe impairment of baroreflex function eliminated the normal circulatory buffer against vasodilator-induced hypotension. Abrupt and profound reductions in blood pressure and the development of fetal distress in response to hydralazine occurred in the patients with higher initial blood pressures. In addition, the present results suggest that phenomena such as the blood pressure lability and increased responsiveness to angiotensin that characterize preeclampsia are, at least in part, reflections of baroreflex dysfunction.

Adult↗
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↗