Intracranial pressure and fetal heart rate patterns in a case of hydrocephaly

A hydrocephalie fetus at term was studied during labor by means of direct continuous fetal heart rate, intracranial and intra-uterine pressures. Baseline instantaneous fetal heart rate pattern was characterized by periodic accelerations and increased short-term variability. This pattern was unchanged despite insertion of an intracranial catheter and instillation of isothermic saline. Atropine, given to the mother, produced a marked rise in fetal heart rate and a decrease in variability. Intracranial pressure, before and after decompression, always exceeded intrauterine pressure.After cranial decompression, typical, terminal fetal heart rate changes were noted, probably due to acute intracranial damage with secondary hypoxia. Theoretical and clinical implications of these observations are discussed. Specific fetal heart rate changes in hydrocephalic fetuses are not definable at this time.     

Heart rate pattern of a hydrocephalic fetus during cephalocentesis

Antepartum heart rate recording was performed prior to, during and after cephalocentesis of a hydrocephalic fetus. Signs of fetal distress appeared only after withdrawal of about half of the intraventricular fluid volume, and subside slowly after cessation of the procedure.     

Sinusoidal fetal heart rate pattern during labor

Of 1280 consecutive fetuses monitored internally with a scalp electrode for at least 10 minutes during labor, 54 (4.2%) demonstrated the sinusoidal heart rate (SHR) pattern. Seven of these demonstrated the SHR pattern for more than 90 minutes. In six of these seven cases, the SHR pattern occurred during oxytocin administration. The SHR group did not differ from the 1226 fetuses not demonstrating the SHR pattern (NSHR group) in Apgar scores, incidence of other fetal heart rate abnormalities, or passage of meconium. The scalp pH was obtained from three fetuses in the SHR group and was above 7.30 in each. Alphaprodine administration during labor was associated with development of the SHR pattern, whereas other narcotic administration was not. The significance of "atypical" SHR pattern with increased amplitude is discussed, along with the need to adhere to strict definition of the SHR pattern.     

Routine electronic monitoring of fetal heart rate and uterine activity during labor.

Routine electronic monitoring has been performed on 2411 labor patients at Booth Memorial Medical Center. Most recently, 88% of all patients delivered were monitored. As a direct result of this program, intrapartum stillbirths have been dramatically reduced from 1.2/1000 livebirths to 0.5/1000 livebirths. Perinatal mortality for fetuses over 1000 g has fallen to 8.8/1000 deliveries. Apgar scores below 6 at 5 minutes have decreased from a rate of 24/1000 to 14/1000 livebirths. No increase in cesarean sections for fetal distress has occurred although the primary cesarean section rate has increased over the past 10 years, apparently unrelated to fetal monitoring. It is strongly recommended that all patients in labor be monitored by currently available technics.     

Significance of exaggerated fetal heart rate accelerations during active labor

One hundred fifty-three of 1,289 patients (11.9%) monitored during labor were identified as having exaggerated fetal heart rate accelerations (EFHRAs), defined as accelerations of the fetal heart rate above the baseline of 30 beats/min or greater and lasting at least 30 seconds. Comparisons of patients with and without EFHRAs showed that the only difference between the two groups was a higher percentage of nulliparous patients in the EFHRA group. Comparisons of intrapartum complications showed a decreased incidence of meconium staining and an increased percentage of abnormal labor patterns in the EFHRA group. Comparisons of neonatal outcome statistics showed lower perinatal morbidity and higher mean birth weight in the EFHRA group.     

Computerized fetal heart rate analysis in labor

Observer variation in visual analysis of fetal heart rate (FHR) records is reportedly high, but can be avoided by computerized numerical analysis. The FHRs of 394 women in labor at 37 or more weeks' gestation were recorded on-line and analyzed to examine how different patterns related to outcome, as judged by umbilical arterial base deficit or Apgar score on delivery. The range of normality and the diversity of patterns of those delivered without acidemia were great. Late decelerations were of poor prognostic value. There was an increase in FHR variation during labor averaging 40%. In this preliminary study, conventional attributes of the FHR, alone or in combination, did not predict metabolic acidemia. Epidural analgesia in 240 women was identified as a confounding variable that significantly affected FHR patterns without influencing the condition of the infant at birth. It was associated with a higher FHR, less FHR variation and fewer decelerations, primiparity, longer labors, more operative deliveries, and a threefold greater cesarean rate. The rise in basal FHR, perhaps due to a rise in maternal temperature, may partly explain the high intervention rate in those without fetal acidemia.     

Pressure in the hydrocephalic fetal head during the first stage of labor

Intraamniotic pressure was studied in the 30th week of amenorrhea in relationship with fetal intracranial pressure with open-tip catheters. The fetus had a severe hydrocephalus (echoscopy 16 cm) due to a teratologic malformation of the cerebrum. Clinically nonoperative treatment was indicated. Intracranial pressure (X) was invariably higher than intraamniotic pressure (Y) between contractions: Y = 2.04 + 0.54 X, and during contractions: Y = 5.30 + 0.55 X. There was no definite relationship between intrauterine and intracranial pressure, and the fetal tachogram. A definite relationship was established with the supine position of the patient and decelerations in the fetal tachogram. It is suggested that when fetal cardiac decelerations are seen during the first stage of labor it seems advisable to look for factors such as umbilical cord compression and decrease of materno-placental perfusion rather than fetal head compression.     

Clinical significance of fetal heart rate patterns during labor. VIII. Breech presentations

The fetal heart rate (FHR) tracings of 302 consecutive breech presentations were analyzed to assess their potential value in clinical practice. There were 274 singleton births, 27 first twins and 1 triplet. Ten percent of the gestations were greater than or equal to 42 weeks, and 26% were less than or equal to 36 weeks. Infants premature by weight (less than 2,500 gm) made up 32%. Only 33.3% had no decelerations, and 63.0% had variable or variable-late decelerations. The latter group had a significantly higher incidence of depressed neonates and neonatal deaths. When accelerations were present, there were significantly fewer depressed infants and neonatal deaths. Overall the perinatal mortality (PNM) was 7.9%; for premature infants it was 27%, postterm 3% and term 1%. There was a 31% incidence of cesarean section. The PNM, when analyzed according to route of delivery, was no different for the very-low-birth-weight, low-birth-weight and term infants. Weight-specific mortality accounted for the apparent difference among the very-low-birth-weight infants. The high incidence and pathophysiology of cord compression (for first- and second-stage labor) may explain the higher incidence of depression in breeches as compared to cephalics. FHR monitoring should be done throughout delivery in order for the physicians to intervene on time when fetal distress is imminent.     

The fetal sound environment during vibroacoustic stimulation in labor: effect on fetal heart rate response.

Nine pregnant women near term, with medical indications for internal monitoring during labor, were studied to determine the transmission of sound across maternal soft tissues during vibroacoustic stimulation with an electronic artificial larynx. A miniaturized hydrophone was placed transcervically at the level of the fetal neck under ultrasound guidance. Intrauterine sound pressure levels were measured before and during stimulation applied at 1 and 0 cm from the surface of the maternal abdomen. When the electronic artificial larynx was placed at a distance of 1 cm from the maternal abdomen, the intrauterine sound pressure level averaged 75 dB at frequencies between 0-5000 Hz. However, when the electronic artificial larynx was firmly applied on the maternal abdomen, intrauterine sound pressure levels were enhanced by more than 20 dB (P less than .001) and averaged 95 dB at all frequencies between 87-20,000 Hz. Baseline intrauterine sound pressure levels consisted of low-frequency sound with intensity of 85 dB at 12.5 Hz, decreasing to 60 dB at 100 Hz and less than 40 dB above 200 Hz. There was a significant correlation (r = 0.78, P less than .02) between the duration of the first fetal heart rate (FHR) acceleration following stimulus and the overall intrauterine sound pressure level at the time of the stimulus. Our data suggest that a threshold of 94 dB intrauterine sound pressure level is necessary to produce a consistent FHR response during active labor.     

Evaluation of fetal heart rate patterns during the second stage of labor through fetal oximetry.

The purpose of this study was to assess the feasibility and accuracy of fetal pulse oximetry during the second stage of labor in cases with abnormal fetal heart rate (FHR) patterns with reference to postpartum acid-base status and Apgar scores. Forty-eight parturients with normal and 20 parturients with abnormal FHR tracings during the second stage of labor were monitored by fetal pulse oximetry and postpartum umbilical artery pH, pO(2), pCO(2) values and 1- and 5-min Apgar scores. The mean SpO(2) value was 55. 47 +/- 9.95% in cases with normal and 52.55 +/- 16.42% in cases with abnormal FHR patterns. A significant correlation was noted between fetal SpO(2) and umbilical artery pH in cases with normal (r = 0.76, p < 0.05) as well as in cases with abnormal FHR patterns (r = 0.78, p < 0.05). No significant correlation was found between fetal SpO(2) and Apgar scores at 1 and 5 min in cases with normal FHR patterns. On the contrary a significant correlation was noted in cases with abnormal FHR patterns. A normal FHR pattern alone is reassuring. In cases with abnormal FHR, fetal pulse oximetry is an objective method for distinguishing a hypoxic fetus.     

Clinical significance of fetal heart rate patterns during labor. II. Late decelerations.

Among a population of high-risk patients in labor who had continuous "direct" electronic monitoring, 147 presented late decelerations and 598 had no decelerations at the time the first stage was completed, or a cesarean section decided upon. A variety of clinical aspects of mother and fetus were analyzed, considering some alterations observed in the FHR pattern. Apgar scores were lower among decelerations, and there was a negative correlation between these two. Maternal pathology, other than PRM, was higher among decelerations and these required enhancement more often. There was very high association with tachycardia, saltatory, and fixed baseline among decelerations, and these infants were very often distressed and born depressed. Within the group of decelerations, small fetuses had lower Apgar scores. There was a negative correlation between number of decelerations and Apgar score. The small fetuses had a high incidence of tachycardia and fixed baseline, saltatory being almost absent. Their neonatal outcome was poor. A comparison of fetal response to distress was done considering age of gestation (premature, term, and postmature) and found to be different. The mechanisms involved in late deceleration are discussed, reviewing the published experimental work. When interpreting FHR patterns, age of gestation should be one of the most important considerations.