Maurice L. Druzin

Maternal smoking causes fetal hypoxia: Experimental evidence

Cigarette smoking during pregnancy has been related to poor perinatal outcome. To investigate the changes in maternal and fetal arterial blood gases associated with smoking, five chronically catheterized pregnant rhesus monkeys were exposed to standard cigarette smoking (N = 5) and nicotine-free herbal cigarette smoke (N = 3). The only consistently reproducible and significant finding was a drop in fetal PO2. The timing of the decline in PO2 and the similar responses to standard and nicotine-free cigarette smoke make carboxyhemoglobin the most likely causative factor.

Antepartum fetal heart rate testing. VII. The significance of fetal bradycardia.

Abstract Antepartum fetal heart rate testing (AFHRT) was utilized in the assessment of fetal status on a large clinical service. The nonstress test (NST) was used as the primary approach. The contraction stress test (CST) was used in the face of persistent nonreactivity. The significance of fetal bradycardia occurring during AFHRT was assessed. Bradycardia was defined as a fetal heart rate (FHR) of 90 bpm or a reduction in FHR of 40 bpm below baseline, for 60 seconds or greater. In a 2-year period, there were 28 cases of bradycardia during 3,754 tests. A total of 24 cases were sent for delivery on the same day while four cases were managed in variable fashion. In 16 cases the tests were classified as nonreactive (abnormal) and the patients were sent for delifery on the same day. There was a 50% incidence of emergency delivery for fetal distress in labor in this group. In eight cases the tests were classified as reactive (normal) and the patients were sent for delivery on the same day. The incidence of fetal distress in labor with emergency delivery was 50%. Five of 10 patients with decreased amniotic fluid volume either on ultrasonic evaluation or by clinical estimation developed fetal distress in labor. There were three cases of congenital anomalies and one case of intrauterine growth retardation which exhibited diminished amniotic fluid. The occurrence of fetal bradycardia during AFHRT denotes a fetus at increased risk of developing fetal distress in labor. This type of test should be considered abnormal and consideration should be given to delivery of the fetus.

Antepartum fetal heart rate testing: XII. The effect of manual manipulation of the fetus on the nonstress test

A prospective study of 790 patients was performed in order to examine the role of manual manipulation of the fetus in the nonstress test. The patients were assigned randomly to two groups based on the last two digits of their hospital number. The odd-numbered patients underwent manual manipulation of the fetus prior to the onset of the nonstress test; the even-numbered patients did not. There was no significant difference between the two groups with respect to the indications for testing and the total number of tests. There was no statistically significant difference between the two groups with respect to the ratio of reactive to nonreactive nonstress tests and the mean duration of testing. Simple manual manipulation of the fetus does not seem to change the outcome in antepartum fetal heart rate testing when the nonstress test is the primary one.

Effect of catecholamine on fetal breathing activity in rhesus monkeys

The effect of various catecholamines on fetal breathing movements (FMB) was studied in 10 established chronic fetal rhesus monkey preparations. Norepinephrine, epinephrine, isoproterenol (all 1:10(5) [w/v] in concentration), or saline was infused intravenously to the fetus, each on five separate occasions. The infusion of the catecholamines was started at 0.02 ml/min and increased in a stepwise fashion until the fetus exhibited cardiovascular responses. The infusion rate was then maintained for 30 minutes to observe FBM. The incidence of FBM was determined for each 5-minute period and also expressed as a percentage of preinfusion values. Statistical analysis revealed that the incidence of FBM was significantly increased by isoproterenol and decreased by norepinephrine. Epinephrine did not consistently alter the incidence of the FBM.

Intrauterine growth of chronically instrumented rhesus monkey fetuses

The effect of surgical and experimental manipulations on intrauterine growth of the fetus was investigated in 61 rhesus monkey fetuses in which chronic preparations were attempted. The surgical procedure consisted of hysterotomy and insertion of vascular catheters and included unilateral ligation of the fetal carotid artery. The mother was kept in a restraining chair after the operation for the duration of the preparation (0 to 39 days). Thirty-four fetuses who died within 48 hours after operation served as the control group for the growth parameters. The remaining fetuses that survived 7 days or more after the operation were included in the experimental group. Body weight, crown-rump length, crown-heel length, and foot length of the fetus and placental weight were measured at the termination of the preparation. There were significant linear correlations between all parameters and gestational age. Comparison between the control and experimental groups revealed that none of the parameters from the experimental group differed significantly from those of the control group. No relationships were found between the duration of the preparation and any of the parameters. Total brain weights from 19 fetuses exhibited a significant increase with gestational age and these values were within the normal range reported previously. There were no significant differences in weight between right and left cerebral hemispheres. No evidence of unequal blood flow to the cerebral hemispheres was found with the radioactive microsphere technique. The data suggest that the surgery performed on both the mother and the fetus and prolonged maternal restraint did not alter intrauterine fetal development.