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PubMed1986

The relationship between antepartum fetal heart rate, intrapartum fetal heart rate, and fetal acid-base status.

The relationships between antepartum baseline fetal heart rate, baseline variability, accelerations, decelerations, and fetal movement and intrapartum fetal heart rate, fetal acid-base assessment at delivery, and Apgar scores 1 and 5 minutes after delivery were studied in 290 mature pregnancies. There was a significant relationship between antepartum and intrapartum baseline fetal heart rate and baseline variability. There was no relationship between antepartum and intrapartum accelerations or decelerations. There was no correlation between antepartum fetal heart rate or fetal movement and fetal acid-base status at delivery or Apgar scores 1 and 5 minutes after delivery. There was a trend for decreased accelerations and decreased fetal movements to be associated with a low Apgar score 1 minute after delivery.

Acid-Base Equilibrium↗
PubMed1986

Sequential nonstress testing with use of each fetus as its own control.

The sequential nonstress tests of 126 high-risk fetuses were assessed for baseline fetal heart rate, acceleration frequency, amplitude, and duration and the observance of fetal heart rate decelerations. In 108 fetuses (563 tests) with normal perinatal outcomes, no significant trends in these parameters were found. In 18 fetuses (104 tests) with perinatal compromise, 16 had significantly declining acceleration frequencies, 15 had decreasing acceleration duration, four had rising mean baseline rates, and seven, in their last test before delivery, had repetitive late or severe variable decelerations. The last tests of 11 of these 18 fetuses met institutional criteria for reactivity. When the nonstress tests of compromised fetuses were viewed sequentially, acceleration frequency declined by an average of 59% and acceleration duration by an average of 40%. Sequential assessment of the nonstress test, when compared with the use of standard reactivity criteria, improved test sensitivity from 39% to 89% and negative predictive value from 91% to 98%. We conclude that sequential nonstress test assessment in individual fetuses may improve the diagnostic value of this modality and lead to earlier recognition of fetal compromise.

Female↗
PubMed1988

Fetal acoustic stimulation in early labor in patients screened with the admission test.

Fetal heart rate reactions to the fetal acoustic stimulation test were investigated in 952 women in early labor. All had cephalic presentations (greater than 33 weeks of gestation) and were screened with a 15-minute fetal heart rate recording (admission test) before the sound stimulation was applied. Three different types of responses were observed: type I, an accelerative response; type II, a biphasic response with acceleration(s) followed by a deceleration; type III, no response or a prolonged deceleration (greater than 60 beats/min and greater than 60 seconds). A type I response was recorded in 98.0% of the women after a reactive admission test result, in 90.2% after an equivocal admission test result, and in 42.9% after an ominous admission test result. Fetal distress in labor occurred in these three groups in 2.0%, 22.2%, and 35.7% of cases, respectively. The risk for fetal distress was high after an ominous admission test and a type III response on the fetal acoustic stimulation test (75.0%). The fetal acoustic stimulation test might be of value in labor and give additional information about fetal well-being in patients previously screened by the admission test. Testing time can be shortened after an equivocal admission test.

Acoustic Stimulation↗
PubMed1989

Heart rate patterns in normoxemic, hypoxemic, and anemic second-trimester fetuses.

Fetal heart rate monitoring was performed immediately before cordocentesis on 71 occasions on 49 patients at 20 to 26 weeks' gestation. In the normoxemic, nonanemic fetuses, the basal fetal heart rate was 120 to 160 beats/minute, the baseline variability was more than 5 beats/min, and there were no prolonged decelerations. Accelerations were present in 19 of the 25 recordings. In the tracings from the hypoxemic (n = 11) or anemic (n = 35) fetuses, there was tachycardia, baseline variability of less than 5 beats/min, and prolonged fetal heart rate decelerations. However, the sensitivity of these pathologic patterns in predicting moderate-to-severe hypoxemia or anemia was 45% and 33%, respectively. The data demonstrate a gestation-dependent maturation of both normal and pathologic fetal heart rate patterns.

Anemia↗
PubMed1989

Umbilical artery flow velocity waveforms during acute hypoxemia and the relationship with hemodynamic changes in the fetal lamb.

The contributions of the variables of the fetal circulation to changes in the pulsatility index of the umbilical artery flow velocity waveform have not been assessed. Acute fetal hypoxemia was induced by 60 to 90 seconds of total occlusion of the maternal common internal iliac artery in six sheep. Mean fetal PO2 levels decreased from 26.0 to 18.3 mm Hg (p less than 0.01) after occlusion of uterine blood flow. Fetal heart rate decreased from 188 to 121 beats per minute at the end of occlusion (p less than 0.05). Placental vascular resistance did not change during the heart rate deceleration. The pulsatility index increased from 0.86 during the control period to 1.27 at the end of occlusion (p less than 0.05). After fetal parasympathetic blockade with atropine, fetal heart rate and placental vascular resistance did not change during occlusion. The pulsatility index did not change during occlusion after parasympathetic blockade. It is concluded that the changes in the umbilical artery pulsatility index during late decelerations in the fetal heart rate pattern appear to be primarily associated with changes in fetal heart rate and bear no relationship with placental vascular resistance.

Acute Disease↗
PubMed1990

Intrapartum asphyxia in the preterm fetus less than 2000 gm.

The incidence of intrapartum asphyxia in the preterm fetus less than 2000 gm (6%) is greater than that in the mature fetus (2%). Severe antepartum hemorrhage is the only clinical marker predictive of asphyxia in the preterm fetus. Marked deceleration patterns and particularly late decelerations may be of predictive value for asphyxia. However, many intrapartum asphyxial episodes are not identified on the basis of clinical observations. Consistent diagnosis of intrapartum asphyxia in the preterm fetus requires routine umbilical cord blood gas and acid-base assessment at delivery.

Asphyxia Neonatorum↗
PubMed1990

Prophylactic intrapartum amnioinfusion: a randomized clinical trial.

Amnioinfusion was performed in a prospective, randomized trial of 60 women in the latent phase of labor with oligohydramnios, as defined by an amniotic fluid index less than or equal to 5.0 cm. All fetuses were at least 37 weeks' gestational age, had normal baseline fetal heart rate variability, and no clinically significant fetal heart rate decelerations at the outset. Subjects in the amnioinfusion group (n = 30) were titrated to and maintained at an amniotic fluid index level greater than or equal to 8.0 cm throughout labor. In the group receiving amnioinfusion, significantly lower rates of meconium passage (p = 0.04), severe variable decelerations (p = 0.04), end-stage bradycardia (p = 0.05), and operative delivery for fetal distress (p = 0.002) occurred. Significantly higher umbilical arterial blood pH values were also noted in the infusion group (p = 0.02). We conclude that prophylactic intrapartum amnioinfusion is an important technique for the reduction of intrapartum morbidity.

Adolescent↗
PubMed1990

What is fetal distress?

Fetal distress is a widely used but poorly defined term. This confusion of definition compounds the difficulty of making an accurate diagnosis and initiating appropriate treatment. The fetus reacts at the onset of asphyxia with a remarkable series of responses, primarily a complexly regulated redistribution of blood flow that serves to limit the deleterious effects of oxygen limitation in vital organs. This enables the fetus to survive asphyxia intact unless the insult is profound or prolonged. The most common asphyxial stresses imposed on the fetus during labor are insufficiency of uterine blood flow, or insufficiency of umbilical blood flow, and occasionally decrease in uterine arterial oxygenation. Each of these stresses produces characteristic fetal heart rate patterns: late decelerations, variable decelerations, or prolonged bradycardia. There is strong evidence that the presence of normal fetal heart rate variability represents normal central nervous system integrity, including adequate oxygenation. A decrease or loss of variability in the presence of these patterns is a sign that the physiologic compensations are overwhelmed as a result of the severity of asphyxia. Knowledge of the fetal responses to asphyxia, together with the known evolution of fetal heart rate patterns during asphyxia, should allow a more accurate definition of the onset of unacceptable asphyxia, and more rational management and timing of intervention.

Asphyxia↗
PubMed1991

The effect of maternal cocaine use on the fetus: changes in antepartum fetal heart rate tracings.

Fetal heart rate tracings of pregnancies complicated by cocaine use were analyzed to evaluate the effects of subacute maternal cocaine use on the fetus. Nonstress tests were performed twice weekly on patients from the perinatal substance abuse clinic with screening of maternal urine samples for cocaine, amphetamines, phencyclidine, and opiates at the time of each examination. Nonstress tests performed when the urine toxicology screen was positive for cocaine alone (positive cocaine nonstress tests) were paired with those from the same patient but performed when the screen was negative (negative cocaine nonstress tests). The nonstress tests were analyzed with the Lyons scoring system, which evaluates the baseline heart rate, the oscillatory amplitude of the baseline, the oscillatory frequency, decelerations, and accelerations. Twenty pairs of nonstress tests from 20 patients were analyzed. The total score was higher on the negative cocaine nonstress test in 70% of the pairs and equal in the remaining 30% (p less than 0.001). Significant differences occurred in the oscillatory amplitude (p less than 0.001), frequency (p = 0.002), and acceleration scores (p = 0.03) but not the fetal heart rate baseline or the deceleration scores. The observed changes may reflect alterations in fetal central nervous system neurotransmitters and fetal state regulation, which may affect the developing central nervous system of cocaine-exposed fetuses and in turn play a role in the developmental and behavioral abnormalities observed in cocaine-exposed infants.

Cocaine↗
PubMed1992

Change in electrocardiogram T-wave amplitude during umbilical cord compression is predictive of fetal condition in sheep.

OBJECTIVE: The purpose of this study is to assess the usefulness of the dynamic change in T/QRS ratio in fetal electrocardiograms in predicting the fetal condition when repetitive variable decelerations are seen in intrapartum cardiotocograms. STUDY DESIGN: We investigated the relationship, using linear regression and Wilcoxon's test, between T/QRS and blood gas values, catecholamine concentrations, and blood pressure during repetitive cord compression in five chronically instrumented lamb fetuses. RESULTS: T/QRS during cord compression correlated significantly (p less than 0.01) with fetal arterial pH (r = -0.7711), norepinephrine concentration (r = 0.7551), and duration of elevated blood pressure during compression (r = -0.8619). Fetal arterial pH and base excess were lower, the duration of elevated blood pressure during compression was shorter, and carbon dioxide partial pressure and catecholamine concentrations were higher in the stage with higher (greater than 0.50) T/QRS during compression (p less than 0.005). CONCLUSION: We can estimate the severity of fetal distress by measuring T/QRS near the bottom of the decelerations.

Animals↗
PubMed1995

Ultrasonographic assessment of fetal growth: comparison between human and ovine fetus.

OBJECTIVE: Our purpose was to evaluate the rate of ovine fetal growth for several body parameters by serial ultrasonographic measurements and to compare them with analogous data in the human fetus. STUDY DESIGN: Forty-three ewes with singleton gestations were studied. Four parameters were measured: biparietal diameter, abdominal circumference, femur length, and tibia length. Ultrasonographic examinations were performed weekly from 50 to 138 days of gestation (term 147 days). Quadratic regression analysis was used to describe each data set. RESULTS: The biparietal diameter showed a significant deceleration of its growth rate. The abdominal circumference showed a linear growth pattern. Both femur and tibia revealed a significant acceleration of the growth rate. CONCLUSION: The ovine fetal growth pattern is different from that observed in the human fetus, in which all four parameters show deceleration of the growth rate in late gestation. In comparison to the ovine, the human fetus reaches similar abdominal circumference and femur length values at term, but in a gestational period that is twice as long. In sharp contrast to abdominal circumference and femur length growth, the biparietal diameter has a similar growth rate in both species. Thus the human fetus has a slower rate of somatic growth and its greater biparietal diameter at term results from the longer gestational period.

Abdomen↗
PubMed1995

Effects of intracervical prostaglandin E2 on fetal heart rate and uterine activity patterns in the presence of oligohydramnios.

OBJECTIVE: Our purpose was to compare fetal heart rate patterns and uterine activity before and after preinduction prostaglandin E2 administration in the presence or absence of oligohydramnios. STUDY DESIGN: In a retrospective case-controlled review we examined cases in which prostaglandin E2 (Prepidil) was inserted intracervically for gravid women requiring an induction of labor in the presence of either oligohydramnios (amniotic fluid index < or = 5.0) or adequate fluid (amniotic fluid index 5.1 to 23.9). Uterine activity and fetal heart rate tracings that were begun 1 hour before and continued for 6 hours after dosing were interpreted without knowledge of amniotic fluid volume. RESULTS: Cases in the oligohydramnios (n = 51) and adequate fluid (n = 49) groups were the same for maternal age, race, parity, gestational age, and predose Bishop score. Patients with oligohydramnios had more high-amplitude contractions in the first hour after dosing (9.0 +/- 1.2 vs 6.1 +/- 0.9, p < 0.05), but there were no significant differences in the frequency or duration of contractions during the subsequent 5 hours. Uterine hyperstimulation was not seen, and there were no differences in the frequency of variable or late fetal heart rate decelerations. CONCLUSION: For pregnancies undergoing preinduction cervical ripening with intracervical prostaglandin E2, the presence of oligohydramnios was not associated with a greater risk of fetal heart rate decelerations, although contractions were more common during the first hour after dosing.

Adult↗
PubMed1989

Human jaw movement in mastication and speech.

The study of jaw movement in humans is a primary source of information about the relationship between voluntary movement and more primitive motor functions. This study focused on the geometric form of the velocity function, as measured by linear voltage displacement transducer. Movement amplitudes, maximum velocities and durations were greater in mastication than in speech. Nevertheless, there were detailed similarities in the shape of the normalized velocity functions. In jaw-closing movements, the normalized functions were similar in form over differences in rate, movement amplitude (speech movements) and the compliance of the bolus (mastication). In opening movements, the functions for mastication and speech were again similar over differences in amplitude and compliance. However, they differed in shape for fast and slow movements. Normalized acceleration and deceleration durations were approximately equal in rapid movements, whereas, for slower movements, deceleration took substantially longer than acceleration.

Biomechanical Phenomena↗
PubMed1981

Probing the micelle/water interface by a rapid laser-induced proton pulse.

The laser-induced pH jump (Gutman, M. and Huppert, D.J. (1979) Biochem. Biophys. Methods 1, 9-19) has a time resolution capable of measuring the diffusion-controlled rate constant of proton binding. In the present study we employed this technique for measuring the kinetics of protonation-deprotonation of surface groups of macromolecules. The heterogeneous surface of proteins excludes them from serving as a simple model, therefore we used micelles of a neutral detergent (Brij 58) as a high molecular weight structure. The charge was varied by the addition of a low concentration of sodium dodecyl sulfate and the surface group with which the protons react was an adsorbed pH indicator (bromocresol green or neutral red). The dissociation of a proton from adsorbed bromocresol green is slower than that from free indicator. This effect is attributed to the enhanced stabilization of the acid form of the indicator in the pallisade region of the micelle. The pK shift of bromocresol green adsorbed on neutral micelles is thus quantitatively accounted for by the decreased rate of proton dissociation. Indicators such as neutral red, which are more lipid soluble in their alkaline form, do not exhibit such decelerated proton dissociation in their adsorbed state nor a pK shift on adsorption to neutral micelles. The protonation of an indicator is a diffusion-controlled reaction, whether it is free in solution or adsorbed on micelles. By varying the electric charge of the micelle this rate can be accelerated or decelerated depending on the total charge of the micelle. The micellar charge calculated from this method was corroborated by other measurements which rely only on equilibrium parameters. The high time resolution of the pH jump is exemplified by the ability to estimate the diffusion coefficient of protons through the hydrated shell of the micelle.

Colloids↗
PubMed1994

Biphasic protonation of hydrophilic cargo agents in unilamellar phospholipid vesicles: implications about cargo location.

The commonly used cargo agents for liposome entrapment, chromate and 5(6)-carboxyflourescein (CF), have been sequestered in small unilamellar vesicles composed of dipalmitoylphosphatidylcholine through preparations involving either sonication or extrusion methods. Once loaded, these water-soluble chromophoric cargo agents have been exposed to small quantities of externally applied acid solution, which decreases the pH from neutral to approx. 6. By monitoring photometrically the time profile of the protonation of the sequestered chromophores, it is evident that the uptake of protons by each cargo agent is biphasic. An immediate spectral change is followed by further change over 10-40 min, where the extent of protonation occurring in each time frame is approximately equal. The vesicles themselves are unaffected by the induced pH change. The leakages of both chromate and CF from loaded sonicated vesicles were monitored at both 25 degrees C and 45 degrees C. Overall, the leakage processes exhibited a deceleration over time. The biphasic protonation and decelerating leakage phenomena are together interpreted in terms of a mechanism of cargo loading involving an intercalation of the water-soluble agent along with water into the vesicle bilayer, rather than involving internal capture of the cargo inside the vesicles, or through electrostatic interactions with the bilayer surfaces. In addition, the measured extents of cargo loading are more consistent with calculated estimates of loading through bilayer intercalation than with those for internal capture.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1982

A brief correction procedure for the management of high rate spitting in a profoundly retarded girl.

This study demonstrates the effectiveness of a brief correction procedure in decelerating a high rate anti-social behaviour (spitting) in a profoundly retarded girl. A simple correction procedure seemed as effective as a more elaborate procedure incorporating positive practice elements, and gains were sustained with some variability over an extended period of time. No reliable increases in collateral behaviours were noted to result from the deceleration in spitting.

Behavior Therapy↗
PubMed1995

Alterations in heart rate and pupillary response in persons with organic solvent exposure.

Cardiac and pupillary reactivity were examined in 25 persons with a history of exposure to organic solvents and 19 nonexposed controls during performance of a counting and a choice reaction task. The solvent-exposed group demonstrated an atypical pattern of responding across tasks. While control subjects showed a decline in heart rate across the two conditions (e.g., habituation), exposed persons had an increase in heart rate. Initial pupil diameter was similar for both groups, but only the control subjects exhibited habituation across the two tasks. In the exposed group, higher heart rate was not associated with higher levels of self-reported anxiety. Anticipatory cardiac deceleration preceding unpredictable events was significantly less in the exposed group, but there were no significant group differences on poststimulus acceleration. The results suggest that persons with solvent exposure have a deficiency in the allocation of attention (reduced anticipatory deceleration and decreased pupillary dilation). It is further suggested that difficulty in the allocation of attention produces an increase in tonic sympathetic levels when confronted with a cognitively challenging task. In this experiment, in which the choice reaction task was purposely presented last, and was apparently more challenging for exposed persons, a failure to exhibit autonomic habituation over the course of the session characterized the solvent-exposed group.

Adult↗
PubMed1986

Pontine neuronal response to local cholinergic infusion: relation to REM sleep.

In behaving cats, a cholinergic agonist, carbachol, or Ringer's solution were infused into the pontine reticular formation (PRF). Extracellular microelectrode recordings were obtained from single neurons located 1-4 mm from the infusion site. Sleep polygraphic variables were also recorded. Carbachol microinfusions into the PRF area between the locus coeruleus and the genu of the seventh nerve readily triggered some or all of the tonic and phasic components of REM sleep. The resulting REM-like states had a mean duration of 30 min. In 56 reticular units studied during carbachol infusions, compared to Ringer's, we observed the following significant responses: 26.6% (16 cells) increased discharge rate, 55.4% (31 cells) decreased discharge rate, 12.5% (7 cells) showed no change, while 3.5% (2 cells) showed a biphasic response. Both incremental and decremental neuronal responses evoked by carbachol preceded or coincided with the onset of REM-like sleep periods, and persisted throughout these periods. The subpopulation of cholinoceptive PRF neurons accelerated during both spontaneous and carbachol-induced REM sleep is most likely to account for REM sleep triggering by carbachol. The PRF neurons found to be decelerated by carbachol displayed under control conditions, the accelerated discharge pattern during REM sleep which is typical of PRF neurons. Since either discharge acceleration or deceleration may occur during REM-like states the discharge pattern of this subpopulation of PRF neurons may not be critical for REM sleep generation.

Animals↗