Veikko Kariniemi

EFFECTS OF INTRAMUSCULAR PETHIDINE ON FETAL HEART RATE VARIABILITY DURING LABOUR

The effects of intramuscularly administered pethidine on indices of fetal heart rate (FHR) variability were studied during labour in 20 women. The differential index, describing the short term variability, and the interval index, describing the long term variability, were measured from direct fetal electrocardiograms by a microprocessor‐based ‘on‐line’ system. The indices were measured from 10‐minute samples, once before the pethidine injection and nine times after the injection. The interval index decreased significantly (p <0·01) with the maximum effect 40 minutes after the injection. The differential index also showed a decreasing trend, with a maximum at 40 minutes, but the change was not significant. Both indices returned to the pre‐injection level after 60 minutes. The effect of pethidine on FHR variability during labour might cause difficulties in assessing the fetal state.

Acute effects of smoking on fetal heart‐rate variability

Summary. Smoking a standard filter cigarette caused an acute decrease both in the interval index and the differential index of fetal heart‐rate variability in eight healthy pregnant women at term. The maximum effect occurred 5–10 min after smoking and the indices returned to the presmoking level in 20 min. We suggest that smoking has a dual effect on the fetus: one being narcotic, leading to a lowered interval index, and the other hypoxic, leading to a lowered differential index.

Acute effects of nicotine on fetal heart rate variability

Summary. The effects of nicotine on fetal heart rate (FHR) variability were studied in seven women in the second trimester and eight women in the third trimester of pregnancy by giving them nicotine‐containing chewinggum. The possible effects of carbon monoxide or some other agents of nicotine‐free smoke on FHR variability were tested in eight women in the second and eight in the third trimester of pregnancy by giving them herbal cigarettes to smoke. The gum caused an acute decrease in the interval index of FHR variability in both trimesters, as we have observed previously in association with tobacco smoking, and an acute decrease in the differential index in the second trimester but not in the third trimester. These effects differ from those associated with tobacco smoking, during which the differential index decreased in the third trimester but remained unchanged in the second trimester. In the second trimester the gum elevated the baseline FHR, as did tobacco smoking. In the third trimester, the gum decreased the baseline FHR in contrast to tobacco smoking, which had no effect on it. Smoking a herbal cigarette had no effect on FHR and no depressant effect on FHR variability, as had nicotine. The only fetal response was a transient increase in the interval index 5—10 min after smoking in the second trimester. We conclude that nicotine seems to be responsible for the depressant effect of tobacco smoke on the fetus, as manifested in lowered interval indices. The different responses of the differential index and baseline FHR to tobacco smoking and chewing nicotine‐containing gum at different stages of gestation remain unexplained.

Evaluation of fetal heart rate variability by a visual semiquantitative method and by a quantitative statistical method with the use of a minicomputer.

Endometritis is seen quite commonly in association with retained placental or decidual tissue after an abortion. Repeat curettings in these cases reveal devitalized, necrotic decidual fragments associated with heavy leukocytic infiltrate, a condition known as “postabortion endometritis.” The necrotic decidua -can be recognized microscopically by the presence of “ghosts” of the large decidual cells with prominent large nuclei. The latter eventually disappear and are replaced with homogeneous eosinophilic acellular tissue. The healing process is characterized by the development of granulation tissue and eventually fibrosis may ensue. Calcification and ossification developing in the old, healed inflammatory tissue, or in the area of an old hemorrhage, have long been recognized and examples such as ossification in atherosclerotic plaques, in lungs subjected to long-standing chronic passive congestion, or in old, healed granulomas abound. Ossification developing in the process of postabortion endometritis occurs, in our opinion, in the same manner, because of the inherent metaplastic properties of the mesenchyma1 cells that participate in the healing process. The endometrial bone formation thus described should be clearly set apart from a phenomenon of fetal tissues implanted in the uterus during curettage and subsequently found in the endometrium or endocervix. The tissues found in these cases have included bone, cartilage, muscle, and neuroglia. Roth and Taylor2 found only one case with foci of bone formation among their nine cases of heterotopic cartilage in the uterus, apparently unrelated to a previous abortion. They favored metaplasia of the stromal cells as the origin of the cartilage in their cases because of the finding of apparent transitional areas in three instances and because of the presence of acid mucopolysaccharides in the endometrial stroma adjacent to the cartilage.2 The appearance of mature bony spicules is easily distinguishable from that of malignant mixed Miillerian tumor or of teratoma. Their finding in the endometrial curettings should in no way cause contemplation of hysterectomy. The ossified fragments are most probably expelled with the menstrual discharge within several months, as apparently was the case in the patient described by Hsu.’

Effects of smoking on fetal heart rate variability during gestational weeks 27 to 32

8 healthy mothers in weeks 27-32 of pregnancy gave informed consent for this study of the effects of smoking on fetal heart rate. Analyses of fetal heart rate (FHR) variability were performed at 1-minute intervals from an abdominal fetal electrocardiogram 10 minutes before, during, and 25 minutes after the mother smoked. Maternal heart rate (MHR) was recorded manually. An elevation of MHR and blood pressure occurred during smoking. Blood pressure had returned to initial levels either immediately (systolic) or within 10 minutes (diastolic); however, MHR was still elevated 25 minutes after smoking ceased. Baseline FHR increased 5 minutes after maternal smoking and returned to the normal level in 25 minutes. Correlation analysis shows negative correlations between the differential index and FHR, between differential index and pulse pressure (p.001), between differential index and systolic reading (p.01), and between variability indexes and MHR (p.001). There was also a positive correlation between FHR and MHR as well as between interval and differential indexes (p.001). The main finding of this study is that, at the onset of the 3rd trimester, the human fetus shows the decreasing effects of smoking on both interval and differential indexes, as does the term fetus (the differential index describes the short-term variability and the interval index describes the long-term variability of heart rate).

Antepartum fetal heart rate variability and intervillous placental blood flow in association with smoking

Intervillous placental blood flow and indices of fetal heart rate variability were measured from seven healthy pregnant women in the last trimester of pregnancy, once before and twice after smoking one cigarette. A blood flow reduction was observed in seven, a rise in five, and no change in two measurements. When intervillous placental blood flow decreased both indices of variability decreased (p less than 0.001), and when it increased the short-term component of fetal heart rate variability increased more significantly (p less than 0.001) than did the long-term component (p less than 0.01).

Reduced short-term variability of fetal heart rate in association with maternal hyperglycemia during pregnancy in insulin-dependent diabetic women

The differential index, which describes the short-term component of fetal heart rate variability, and maternal blood glucose levels were measured 109 times in 19 insulin-dependent diabetic mothers in the second half of gestation. An abnormal differential index was observed more often with maternal hyperglycemia (11/45) than with normoglycemia (5/64). A significant negative linear correlation was found between the differential index and the blood glucose level of the mother.

Significant correlation between maternal hemodynamics and fetal heart rate variability

The differential index, describing the short-term component, and the interval index, describing the long-term component, of fetal heart rate variability were measured by an on-line method from the abdominal electrocardiograms of eight fetuses during the third trimester of normal pregnancies while mothers were smoking a cigarette. Maternal heart rate and maternal blood pressure were measured intermittently before, during, and after smoking. Analyses of fetal heart rate variability were performed continuously with the sample time of 1 minute during the experiments. An increase in maternal heart rate and blood pressure, with concomitant decrease in the interval index and the differential index, was observed. The correlation analysis revealed a negative correlation between maternal heart rate and the interval index (p less than 0.001), between diastolic pressure and the differential index (p less than 0.01), and between systolic pressure and the differential index (p less than 0.01).

Fetal heart rate patterns and perinatal outcome of very‐low‐birthweight infants

Summary. The obstetric records of 125 infants weighing 500–1250 g who were born in 1978 and 1979 at the Helsinki University Central Hospital were studied retrospectively to find out any associations between fetal heart rate (FHR) patterns and perinatal outcome. FHR recordings of 79 fetuses were available for study. Normal reactive patterns were observed in nine, nonreactive in 54, decelerations in 58, silent patterns in 45 and combined distress patterns in 36 fetuses. The interval from the first pathological sign to delivery was up to 27 days. Five fetuses in the monitored group died in utero, 26 infants died neonatally and two later. The risk of neonatal death after pathological FHR patterns was lower than after an FHR pattern without abnormality. Idiopathic respiratory distress syndrome (RDS) was diagnosed in 32 infants, of whom 16 died. Forty‐seven fetuses (59%) of the monitored group were delivered abdominally and 32 vaginally. The risk of RDS was not significantly associated with FHR patterns and mode of delivery. We conclude that unlike term fetuses, low‐birthweight fetuses seem to benefit from a period of intrauterine stress reflected in abnormal FHR patterns, if caesarean section is used liberally.

Short term variability of fetal heart rate during pregnancies complicated by hypertension

Summary. The clinical significance of the differential index (DI), which describes the short term variability of fetal heart rate (FHR), in fetal surveillance was assessed in 202 hypertensive pregnancies. The analyses of FHR variability were made by a microprocessor‐based on‐line method using the abdominal fetal electrocardiogram as a triggering signal. The analysis was successful in 258 out of 323 trials (80%). Five perinatal deaths (2.5%) occurred in the whole series. Fetal distress developed in 47 out of 137 patients who had a successful FHR analysis within 1 week of delivery. The sensitivity of the antepartum DI in predicting fetal distress in labour was 46%, predictive value was 88% and specificity 97%. The risk of intrapartum fetal distress after a pathological DI was 4 times that after a normal DI (relative risk), which is highly significant.