Biomedical subjects

L J Groome

Publications and source records attributed to L J Groome.

At least 19 recordsLinked to original sources

PubMed2000

Temporal pattern and spectral complexity as stimulus parameters for eliciting a cardiac orienting reflex in human fetuses.

The purpose of this study was to determine whether temporal pattern and/or spectral complexity were important stimulus parameters for eliciting a cardiac orienting reflex (OR) in low-risk human fetuses. Each of 28 term fetuses was exposed to four sounds formed from the four different combinations of temporal pattern (pulsed, continuous) and spectral complexity (sine wave, /â/). The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz, and fetal R-waves were extracted by using adaptive signal-processing techniques. We found that pulsed sounds elicited a significantly greater decrease in heart rate (HR) than did continuous sounds. However, the HR response was relatively unaffected by spectral complexity. For the pure tone and the phoneme used in this study, our results indicate that temporal characteristics were more effective at eliciting a cardiac OR in human fetuses than was spectral complexity.

Acoustic Stimulation↗

PubMed1999

Spontaneous motor activity in the perinatal infant before and after birth: stability in individual differences.

This study was undertaken to determine if a relationship existed between the duration of spontaneous general movements before and after birth. Twenty-two infants were examined three times as fetuses between 38 and 40 weeks gestational age and three times as neonates between 2 and 4 weeks postnatal age. Motor activity level during active sleep periods was quantified by direct sonographic visualization for fetuses and by videotaped images of trunk movement for neonates. We found that both fetuses and neonates exhibited stable individual differences in motor activity level. In addition, infants who moved at a certain rate as fetuses generally moved at the same relative rate as neonates up to 4-weeks postnatal age. Our findings suggested that individual differences in motor activity level in the 1st month following birth probably arise during fetal life.

Female↗

PubMed1999

High vagal tone is associated with more efficient regulation of homeostasis in low-risk human fetuses.

Homeostasis is maintained primarily by the parasympathetic nervous system and is thought to provide a physiological substrate for the development of complex behaviors. This investigation was undertaken to test the hypothesis that infants with high parasympathetic tone are more efficient regulators of homeostasis than infants with low parasympathetic tone. Respiratory sinus arrhythmia (RSA) was used as a measure of parasympathetic tone, and the efficiency of homeostatic control was quantified, for each infant, by the slope (SRSA) and correlation coefficient (RRSA) of the regression line relating fluctuations in heart period and fluctuations in RSA. To test our hypothesis, we examined the relationship between RSA and both SRSA and RRSA in 34 low-risk human fetuses between 36 and 40 weeks gestation. We found that fetuses who were parasympathetic-dominated had larger SRSA and RRSA values, and hence were more efficient regulators of homeostasis, than fetuses who were sympathetic-dominated. The results of our analyses are important because they establish, very early in development, a physiological basis for the relationship between vagal tone and the development of complex behaviors.

Arousal↗

PubMed1999

Behavioral state affects heart rate response to low-intensity sound in human fetuses.

The cardiac orienting reflex is elicited by a low-intensity sound, it consists of a sustained heart rate (HR) deceleration, and it is a specific physiological correlate of cognitive processing. In this study we examined the relationship between behavioral state and the cardiac orienting reflex in 75 human fetuses between 36 and 40 weeks gestation. Each fetus was stimulated with a 30-s speech sound at an average intensity of 83 dB SPL in quiet sleep (QS) and active sleep (AS). The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz and fetal R-waves were extracted using adaptive signal processing. Fetal behavioral states were assigned based on HR pattern and the presence or absence of eye and general body movements. We found that a significant HR deceleration occurred, in both QS and AS, following stimulus onset. However, HR decelerations occurred more often in QS than AS; and for fetuses exhibiting a HR deceleration, the magnitude of the deceleration was greater in AS compared to QS. In addition, in AS female fetuses exhibited a larger, more sustained HR deceleratory response than male fetuses, but the seconds x gender interaction in QS was not significant. Based on these results, we concluded that behavioral state is an important determinant of the HR deceleratory response in human fetuses.

Acoustic Stimulation↗

PubMed1999

Human fetuses have nonlinear cardiac dynamics.

Approximate entropy (ApEn) is a statistic that quantifies regularity in time series data, and this parameter has several features that make it attractive for analyzing physiological systems. In this study, ApEn was used to detect nonlinearities in the heart rate (HR) patterns of 12 low-risk human fetuses between 38 and 40 wk of gestation. The fetal cardiac electrical signal was sampled at a rate of 1,024 Hz by using Ag-AgCl electrodes positioned across the mother's abdomen, and fetal R waves were extracted by using adaptive signal processing techniques. To test for nonlinearity, ApEn for the original HR time series was compared with ApEn for three dynamic models: temporally uncorrelated noise, linearly correlated noise, and linearly correlated noise with nonlinear distortion. Each model had the same mean and SD in HR as the original time series, and one model also preserved the Fourier power spectrum. We estimated that noise accounted for 17.2-44.5% of the total between-fetus variance in ApEn. Nevertheless, ApEn for the original time series data still differed significantly from ApEn for the three dynamic models for both group comparisons and individual fetuses. We concluded that the HR time series, in low-risk human fetuses, could not be modeled as temporally uncorrelated noise, linearly correlated noise, or static filtering of linearly correlated noise.

Algorithms↗

PubMed1998

Methods used to diagnose premature rupture of membranes: a national survey of 812 obstetric nurses.

OBJECTIVE: To identify methods used to diagnose premature rupture of membranes (PROM). METHODS: A 14-item questionnaire was mailed to 1992 registered nurses certified in inpatient obstetrics to determine information on practice facility, obstetric services, procedures used to obtain vaginal fluids for testing, and methods used to diagnose PROM. RESULTS: A total of 812 (40.8%) surveys were available for analysis. Of tests used to confirm PROM, observation of pooling fluid in the posterior fornix and fern tests were much more likely to be used in teaching and military hospitals and in facilities with tertiary obstetric services than in private hospitals (all P values < .001). To obtain vaginal fluids for fern and nitrazine testing, the dry glove method (ie, insertion of a gloved hand or nitrazine strip into the vagina) was used significantly more often in private hospitals than in teaching or military facilities (P < .001). In addition, the dry glove method was used significantly more often (P < .001) and the speculum examination was used less often (P < .001) to collect vaginal fluids for testing when private physicians performed more than 75% of deliveries at a particular hospital. In contrast, vaginal fluid was obtained during a sterile speculum examination more often in facilities in which more than 75% of deliveries were performed by residents (P < .001), and/or when more than 75% of speculum examinations were performed by nursing personnel (P < .001). Multiple linear regression analyses indicated that observation of pooling fluid and use of the fern test were significantly associated with hospital type, percentage of deliveries by private physicians, and percentage of speculum examinations performed by nursing personnel (all P values < .001). CONCLUSION: A sterile speculum examination is used more often to obtain vaginal fluids for testing and to diagnose ruptured membranes in teaching or military facilities and when nursing personnel have been trained in speculum examinations.

Female↗

PubMed1998

Heart rate dynamics in low risk human fetuses.

Evaluation of nonlinear heart rate (HR) dynamics has received considerable attention in the pediatric literature because such analyses not only provide insight into underlying control mechanisms, but may also help to differentiate between normal and abnormal infants. The purpose of this study was to determine, in eight low risk human fetuses, if nonlinear HR dynamics could be identified by analyzing the dispersion of interbeat intervals at slow (Ds) and fast (Df) HRs. The fetal cardiac electrical signal was captured transabdominally at a resolution of +/- 1 ms. To test the null hypothesis, that the time series is the result of a linear stochastic process, Ds and Df for the original time series were compared with the values calculated for three linear models. The linear models were constructed to preserve the major statistical properties of the original time series, including the mean, SD, and the Fourier power spectrum. For each fetus, there was no evidence of nonlinear cardiac dynamics based on analyses of Ds and Df. In contrast, the distribution of adjacent R-R intervals and the pattern of change across three successive interbeat intervals both revealed significant nonlinearities in HR control in each fetus. If the difference between normal and abnormal infants is the result of aberrant control of nonlinear processes, then our findings indicate that parameters which describe the nonlinearity may be more useful then Ds and Df in assigning a risk status.

Apgar Score↗

PubMed1998

Pregnancy in women with spinal cord injuries.

Most women with spinal cord injuries (SCI) resume normal reproductive function, can have sexual relationships, and become pregnant. Pregnancy is not contraindicated in women with SCI, but pregnant women with acute or chronic SCI pose unique challenges for perinatal health care providers. The normal physiologic changes of pregnancy may predispose women with SCI to potentially life-threatening complications, including autonomic hyperreflexia, pyelonephritis, respiratory insufficiency, thrombophlebitis, and unattended delivery of the infant. This article reviews the effect of SCI on female reproduction, pregnancy, and labor, and summarizes the treatment of the pregnant woman with a spinal cord injury.

Female↗

PubMed1997

Temporal stability in the distribution of behavioral states for individual human fetuses.

Although behavioral state analyses have been useful in differentiating between groups of normal and at-risk fetuses, the large between-subject differences in the percent time spent in the various behavioral states poses a major obstacle in identifying abnormal neurological functioning in individual fetuses. Does this variability represent a true difference in state organization between fetuses, or does it simply reflect individual fluctuations in state control at the time of observation? To answer this question, we examined each of 33 human fetuses for 4 h on three separate days between 38 and 40 weeks gestation. The percent time spent in each behavioral state and in transition and insertion periods was determined for each of the three 4-h study sessions, and within-subject analysis of variance was performed to obtain an objective measure of state profile consistency for each fetus. We found that, on the average, fetuses exhibited remarkable within-subject consistency in their state profiles. However, even among this group of low-risk fetuses, there were significant differences in the degree of state organization achieved by individual fetuses. These findings, which indicate the existence of a well-developed central nervous system before birth, suggest that individual differences in the consistency of behavioral state profiles may be indexing important between-subject differences in neurological development.

Behavior↗

PubMed1997

The heart rate deceleratory response in low-risk human fetuses: effect of stimulus intensity on response topography.

The purpose of this study was to determine the effect of stimulus intensity on heart rate response in 18 low-risk human fetuses between 37 and 40 weeks gestation. Each fetus was stimulated in quiet sleep with a 30-s voice sound at intensities of 80 dB and 90 dB. The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz and fetal R-waves were extracted using adaptive signal-processing techniques. We found that fetuses generally exhibited a 5- to 10-s decrease in heart rate following stimulus onset at an intensity of 80 dB. The response pattern changed from deceleratory to acceleratory when stimulus intensity was increased to 90 dB. Our findings suggest that a heart rate deceleration at low-stimulus intensity may be a component of the orienting reflex in the human fetus.

Analysis of Variance↗

PubMed1997

Similarities and differences in behavioral state organization during sleep periods in the perinatal infant before and after birth.

The purpose of this study was to determine the degree of consistency in behavioral state organization for 30 low-risk human participants examined as fetuses at 38-40 weeks gestation and again as neonates at approximately 2 weeks postnatal age. Behavioral states were assigned similarly for fetuses and neonates in terms of heart rate pattern and the presence or absence of eye and gross body movements. We found that the time spent in a sleep period was distributed among quiet sleep (QS), active sleep (AS), and indeterminate states in virtually identical proportions for fetuses and neonates. However, the only within-subject consistency between the fetal and neonatal periods was in the duration of complete QS epochs. Fetuses made fewer transitions between QS and AS, but neonates had shorter and more structured AS-->QS transitions. These findings suggest that, whereas central nervous system processes governing QS do not change appreciably, the control of AS undergoes significant changes in the 4 weeks spanning the fetal and neonatal periods. We believe that the duration of enclosed QS epochs provides the only stable measure of behavioral state development between the prenatal and postnatal periods.

Eye Movements↗

PubMed1996

Elevated midtrimester mean arterial blood pressure in women with severe preeclampsia.

Although early identification of pregnant women who are at risk for severe preeclampsia may help reduce maternal-perinatal sequelae, an adequate screening test for this disorder has not been described. The purpose of this study was to determine if a group of women (n = 57) who developed severe preeclampsia had a higher midtrimester mean arterial pressure (MAP-2) than a matched group of women (n = 57) who remained normotensive throughout pregnancy and the puerperium. It was found that women who developed severe preeclampsia had a significantly higher MAP-2 than normotensive women and significantly more preeclamptic subjects had an MAP-2 > or = 85 mmHg than did control subjects. Thus, an elevated MAP-2 may help identify women who are at risk for the development of severe preeclampsia.

Adult↗

PubMed1996

Morphology of active sleep--quiet sleep transitions in normal human term fetuses.

Periods of no coincidence (PsNC) among state variables appear to be more predictive of neurobehavioral outcome than the amount of time spent in any particular behavioral state. It has recently been suggested that analysis of the ordering of state variables during a state transition may provide results equivalent to full state analysis. If this were the case, then there ought to be a relationship between the duration of PsNC and fetal heart rate (FHR)-fetal eye movement (FEM) sequencing at the time of a state change. To test this hypothesis, we compared full state analysis with analysis of individual state transitions for 52 normal human fetuses between 38 and 42 weeks of gestation. For the study population as a whole, FHR was the first variable to change in 62 (77%) of 81 1F-->2F transitions and FEM was the first variable to change in 50 (63%) of 79 2F-->1F transitions (chi 2 = 67.9, p < 0.001). Ordering of FHR and FEM at the time of a state change was reversed in 8 (67%) of 12 fetuses with PsNC > or = 15% and is only 6 (15%) of 40 fetuses with PsNC < 15% (chi 2 = 12.5, p < 0.001). We conclude that fetuses who exhibit poor state organization more often display a FHR-FEM sequence at the time of a state transition which is opposite that of fetuses with considerably better state control. However, since only one-third of fetuses with reversed FHR-FEM sequencing actually exhibited more than one such episode, it is unlikely that isolated analysis of state transitions will provide a reliable measure of behavioral state organization in the individual fetus.

Eye Movements↗

PubMed1995

Behavioral state organization in normal human term fetuses: the relationship between periods of undefined state and other characteristics of state control.

Repeated alteration in episodes of quiet sleep and active sleep is a basic feature of behavioral state organization in human fetuses. When compared to normal fetuses, at-risk fetuses generally exhibit extended periods of no coincidence (PsNC), that is, associations between state variables that cannot be classified as a sleep state. The purpose of this study was to determine if fetuses with extended PsNC differ in other state measures from fetuses with short PsNC. Fetal heart rate and fetal eye and gross body movements were collected simultaneously on 85 normal human fetuses between 37 and 41 weeks gestation for a total of 9,135 minutes (mean 108.8 +/- 12.7 minutes, range 85-130 minutes). We found that as percent PsNC increased, the frequency (r = 0.464, p < 0.0001) of state changes increased and the time spent in active sleep (r = -0.456, p < 0.0001) and the number of fetuses entering an awake state (chi 2 = 4.26, p < 0.039) decreased. In contrast, percent PsNC was independent of the length of time spent in quiet sleep (r = 0.070, p > 0.05). We interpret these findings as an indication that extended PsNC may be the result of disruption of homeostatic control mechanisms during active sleep.

Behavior↗

PubMed1995

Motor responsivity during habituation testing of normal human fetuses.

Features of fetal motor responsivity include both the magnitude of the startle response elicited by a single stimulus (i.e., basal reactivity) and the ease by which responding to successive stimuli is inhibited (i.e., habituation). We examined basal motor reactivity and habituation of the motor response in 56 normal human fetuses between 34 and 40 weeks of gestation. Testing consisted of 8 trials of a 1-sec vibroacoustic stimulus (VAS) with a 10-sec interstimulus interval. A score of 0-10 was assigned for each trial based on subjective assessment of intensity and duration of the fetal motor response. Measures of habituation included the ratio of responding after a fixed number of trials divided by the initial response, and the rate of change in the behavioral response over trials. No relationship was found between the rate of motor habituation and either basal reactivity, gestational age, or prestimulus fetal heart rate (FHR) variability. In contrast, more mature fetuses responded less intensely to the first stimulus than did their younger counterparts (r = -0.329, p = 0.005), and fetuses who were initially in a quiet state exhibited a more vigorous startle response as compared to fetuses who were initially in a more active state (r = -0.372, p = 0.001). The relationship between basal reactivity and prestimulus FHR variability was statistically significant even after controlling for gestational age (r = 0.295, p = 0.01). These findings may have important clinical implications regarding the appearance in early life of certain behavioral tendencies such as temperament.

Cognition↗

PubMed1995

Categorization of heart rate-eye movement patterns in human fetuses using the statistical technique of discriminant analysis.

The purpose of this study was to determine if discriminant analysis could be used to categorize fetal heart rate (FHR) - fetal eye movement (FEM) patterns. Statistical characteristics from 27 normal human fetuses at term for behavioral states, transitions, and insertions were established by combining the digitized FHR-FEM data for subjectively identical epochs. The mean FHR, the variance about the mean, and the presence or absence of FEM were calculated for each 3-min block in a sliding moving window with a 1-min step size. For each fetus, discriminant analysis was then used to assign 3-min blocks to either a behavioral state, a transition, or an insertion by comparing the statistical properties of a 3-min block with that of the data base. We found no difference between discriminant analysis and visual assignment in the average time spent in behavioral states 1F, 2F, and 4F, or in the mean duration of the transition/insertion periods. There was a highly significant linear relationship between computer-generated and visually-determined durations for behavioral states 1F (r = 0.972, p < 0.0001) and 2F (r = 0.989, p < 0.0001) and for the transition/insertion periods (r = 0.863, p < 0.0001). We conclude that discriminant analysis is a reliable computer-based method for behavioral state identification.

Discriminant Analysis↗

PubMed1995

Maternal anxiety during pregnancy: effect on fetal behavior at 38 to 40 weeks of gestation.

The purpose of this study was to determine if there is a relationship between fetal behavior and maternal anxiety during pregnancy. The study population consisted of 18 uncomplicated human pregnancies at 38 to 40 weeks gestation. Maternal anxiety was assessed one time using Spielberger's State-Trait Anxiety Inventory. After an overnight fast, each mother was given a standard meal on arrival to the fetal testing unit. Each fetus was examined for 4 hours using heart rate monitoring and real-time sonography. Fetal behavioral states were assigned based on heart rate pattern and the presence or absence of eye and gross body movements. We found that, compared with fetuses of mothers with low trait anxiety scores, fetuses of mothers with relatively high trait anxiety scores spent significantly more time in quiet sleep and exhibited less gross body movement when in active sleep. The results of this pilot study raise the possibility that maternal anxiety during pregnancy may have a significant effect on fetal behavior.

Anxiety↗

PubMed1994

Vagal tone during quiet sleep in normal human term fetuses.

The purpose of this paper was to calculate vagal tone (V) for 17 normal human fetuses in quiet sleep (QS) between 36 and 40 weeks gestation. The fetal cardiac electrical signal was captured transabdominally in 3-min blocks at a rate of 833 times per second and fetal R-waves were extracted using adaptive signal processing techniques. Fetal R-wave interbeat intervals were converted to equally spaced, time-based data, and the low-frequency component was removed using a 21-point third-order moving polynomial. The parameter V was calculated by taking the natural logarithm of the sum of the power densities between 0.3 Hz and 1.3 Hz. We found that fetal breathing was associated with an approximately 25% increase in V as compared to nonbreathing, 3.33 +/- 0.48 versus 2.57 +/- 0.47, p < 0.0001. Furthermore, there was a significant linear relationship between the mean single-fetus V during spontaneous respiration and the mean single-fetus V during normally occurring apneic periods, r = 0.772, p < 0.002. We conclude that respiratory activity is associated with a significant increase in vagal tone for normal human fetuses in QS.

Arousal↗