Effect of long-term cocaine administration to pregnant ewes on fetal hemodynamics, oxygenation, and growth

OBJECTIVE: To assess uterine and fetal blood flows by Doppler velocimetry and fetal growth and oxygenation in pregnant ewes treated daily with cocaine and to determine whether cocaine impairs fetal cardiac and cerebral reactivity. METHODS: The study groups received 70 mg (n = 7) or 140 mg (n = 7) of cocaine and the control group (n = 7) received placebo injected intramuscularly daily on days 60-134. Hemodynamic data were measured at rest and during two acute hypoxic tests at cesarean delivery performed on day 134. RESULTS: The fetal heart rate (FHR) and umbilical and uterine resistance indices (RIs) were higher in the cocaine groups than in the control group (FHR: 187 +/- 8 and 166 +/- 8 beats per minute at 83 and 123 days, respectively, in controls and 9-11% higher in cocaine groups; umbilical RI: 0.79 +/- 0.06, 0.60 +/- 0.04, and 0.52 +/- 0.06, at 83, 105, and 123 days, respectively, in controls and 11-17% higher in the cocaine groups [P < .01]; and uterine RI: 0.40 +/- 0.05, 0.40 +/- 0.04, and 0.37 +/- 0.04, at 83, 105, and 123 days, respectively, in controls and 13-35% higher in cocaine groups [P < .05]). At delivery on day 134, the following characteristics were found to be different in the cocaine groups: fetal weight (4.03 +/- 0.2 kg in controls and 15-21% lower in the cocaine groups [P < .02]), partial pressure of oxygen (26.5 +/- 1.4 mmHg in controls and 15-16% lower in cocaine groups [P < .05]), umbilical RI (0.40 +/- 0.03 in controls and 11-17% higher in cocaine groups [P < .01]), cerebral RI (0.61 +/- 0.03 in controls and 9-15% lower in cocaine groups [P < .01]), and cerebral-umbilical ratio (1.52 +/- 0.04 in controls and 22-23% lower in cocaine groups [P < .001]). During the hypoxic tests, the cerebral RI (P < .05) and the cerebral-umbilical ratio (P < .05) decreased significantly less in the two cocaine groups. The FHR response was reduced significantly in the two cocaine groups (P < .05). CONCLUSION: Long-term exposure to cocaine induces uterine and fetal blood flow disorders, fetal growth restriction, and hypoxia. It reduces the capability of the cerebral vessels to vasodilate and the heart rate to increase during acute hypoxia.     

Experimentally contaminated reabsorbable meshes: their evolution in abdominal wall defects

The effect of maternal hyperglycemia on fetal regional circulation in appropriate for gestational age and small for gestational age fetuses was evaluated. Color Doppler flow imaging and pulsed Doppler ultrasonographic assessments were made on 15 appropriate for gestational age and 19 small for gestational age fetuses, ranging from 33 to 40 weeks' gestation before, 60 minutes, and 120 minutes after a maternal 75 g glucose load. The pulsatility index (PI) was calculated for middle cerebral artery, descending aorta, splenic artery, renal artery, femoral artery, and umbilical artery. Simultaneously, maternal plasma glucose concentration was measured. Baseline PI value (1.50 +/- 0.31) for middle cerebral artery in small for gestational age fetuses was significantly lower than that (1.89 +/- 0.37) in appropriate for gestational age fetuses (p < 0.05); however, there were no significant differences in baseline PI values for other arteries in both groups. In appropriate for gestational age fetuses, the mean PI decreased from 1.89 +/- 0.37 to 1.47 +/- 0.33 at 60 minutes, and to 1.55 +/- 0.32 at 120 minutes (p < 0.05), but no changes were found in the other arteries. In small for gestational age fetuses, there was no significant change in PI value for each artery before and after maternal glucose load. Maternal hyperglycemia induces a significant decrease in cerebrovascular resistance in appropriate for gestational age fetuses but not in small for gestational age fetuses. These results provide a foundation for evaluating the effect of maternal hyperglycemia on fetal regional circulation.     

Plasma exchange in myasthenia gravis

OBJECTIVE: To evaluate whether fetal heart rate (FHR) patterns obtained in nonstress testing within 24 hours of delivery in patients with preterm delivery were associated with histologic acute infection, and if so, whether the associations are with maternal as opposed to fetal acute inflammation (acute amnionitis versus acute umbilical vasculitis). METHODS: The data set included 351 consecutive patients delivering from 22 to 32 weeks' gestation (excluding cases of preeclampsia; nonhypertensive abruption; stillbirth; fetal structural and karyotypic anomalies; Rh isoimmunization and hydrops fetalis; and maternal diabetes and hypertension). Severe variable decelerations were defined as FHR < 70 beats per minute lasting > 60 seconds, and decreased fetal heart variability included both reduced beat-to-beat variability and long-term heart rate cyclicity. Amniotic fluid volume was graded sonographically as part of a fetal biophysical profile. Acute inflammation of amnion (indicative of maternal inflammation) and umbilical cord (fetal inflammation) were scored by a single pathologist blinded to clinical data. RESULTS: Severe FHR variable decelerations were directly related to acute amnionitis (P = .012) and acute umbilical vasculitis (P = .0013). In preterm labor, decreased FHR variability was related to acute amnionitis (P = .005). All observations were independent of amniotic fluid volume or use of tocolytic agents. CONCLUSIONS: Severe variable decelerations and decreased FHR variability at < 32 weeks' gestation are related to histologic evidence of acute inflammation.     

Acute effects of cigarette smoking on fetal cardiovascular and uterine Doppler parameters

The purpose of this study was to assess the effects of smoking one cigarette (nicotine mean 0.63 +/- 0.17 mg) on uterine- and foetal cardiovascular Doppler parameters in healthy pregnant smokers. All pregnancies (n = 16; mean gestational age: 36 +/- 4 weeks) had been uneventful and all foetuses were appropriate for gestational age with normal baseline Doppler parameters and normal foetal outcome (birthweight: 3254 +/- 340 grams). Measurements, performed immediately before and after smoking, included pulsatility index (PI) of umbilical artery (UA), middle cerebral artery (MCA), foetal descending aorta and uterine artery as well as maternal and foetal heart rate. The ratio of UA/MCA PI was used to assess centralisation. Changes in foetal cardiac output were determined by: time-velocity integral times heart rate, at aortic and pulmonary valve level. Foetal heart rate (p < 0.0005, paired t-test) and maternal heart rate (p < 0.05) increased significantly. All other parameters did not change significantly. However, in one additional woman with labile hypertension and increased baseline uterine artery PI (1.9), smoking of one cigarette caused a substantial rise in uterine artery PI to 3.25 ten minutes after smoking. Middle cerebral artery PI decreased from 2.2 to 1.18 with an unchanged cardiac output and umbilical artery PI raising the UA/MCA PI ratio from 0.51 to 0.81, suggesting a brain sparing effect. Smoking of one cigarette raised maternal and foetal heart rate. There was no evidence of other cardiovascular effects or centralisation in healthy foetuses of normal pregnancies, but this might not be true in foetus of pathologic pregnancies.     

Metabolic aspects of a hypoxia test for placental sufficiency

A hypoxia test for placental sufficiency was performed on 24 healthy pregnant women nearing term and 23 high-risk pregnant women in advanced stages of gestation. Hypoxia was induced by inhalation of a breathing mixture containing 7% oxygen through a semi-open system which permitted partial rebreathing, thus preventing hypocapnia. The changes in fetal heart rate (FHR) resulting from maternal hypoxia were recorded continuously by external or internal monitoring. The changes observed in FHR were more marked in high-risk cases. Maternal blood gases were tested before and after 10 min of hypoxia in 10 normal and 10 high-risk patients. In no case was maternal acidosis observed. All pregnant patients regarded as high-risk because of hypertensive disorders or chronic renal disease manifested metabolic alkalosis. This finding cannot be explained. It is regarded as being responsible for the more severe FHR changes through a negative Bohr effect, which reduces the dynamic exchange of oxygen in the placenta. Metabolic alkalosis does not appear in high-risk pregnant women exposed to milder hypoxia by breathing 12% oxygen. The changes in FHR observed during severe maternal hypoxia, i.e., 7% oxygen, are probably due more to maternal metabolic alkalosis than to placental insufficiency. Consequently, the "severe hypoxia test" cannot be used as a test for placental insufficiency.     

Perioperative growth hormone treatment increases nitrogen and fluid balance and results in short-term and long-term conservation of lean tissue mass

STUDY OBJECTIVE: To evaluate changes due to pregnancy on atenolol's pharmacokinetics, response of maternal heart rate to atenolol, and the drug's effect on fetal heart rate. DESIGN: Prospective study. SETTING: Large university teaching hospital. PATIENTS: Fourteen pregnant women who were receiving oral atenolol for cardiac disease were enrolled and 10 completed the study. INTERVENTIONS: Patients were studied for 12 hours during the third trimester (TT) and again 6 weeks postpartum (PP). MEASUREMENTS AND MAIN RESULTS: Fetal heart rates, and maternal heart rates at rest and during exercise were recorded. Maternal plasma and urine atenolol concentrations were measured. Average resting heart rates (TT 68+/-10, PP 62+/-9 beats/min) and maximum heart rate during exercise (TT 100+/-6, PP 87+/-7 beats/min) were significantly higher in the third trimester than postpartum (p<0.05). The 12-hour atenolol area under the curve (TT 0.208+/-0.061, PP 0.215+/-0.089 ng/ml/day) and maximum plasma concentrations during the time of exercise tests (TT 1.07+/-0.39, PP 1.14+/-0.53 mmol/L) were not significantly different. Individual and population pharmacokinetics did not differ significantly between study periods. The fetal heart rate did not correlate with maternal atenolol concentration. CONCLUSION: Constant dosages of atenolol result in higher heart rates during pregnancy compared with the postpartum period. This lack of heart rate control is not due to significant changes in atenolol's pharmacokinetics or plasma concentrations.     

Effects of various flow types on maternal hemodynamics during fetal bypass: is there nitric oxide release during pulsatile perfusion?

OBJECTIVE: This study investigates the role of various flow conditions on maternal hemodynamics during fetal cardiopulmonary bypass. METHODS: Normothermic fetal bypass was conducted under pulsatile, or steady flow, for a 60-minute period. Fetal lamb preparations were randomly assigned to 1 of the 3 groups: steady flow (n=7), pulsatile flow (n=7), or pulsatile blocked flow bypass (n=7), where fetuses were perfused with Nomega-nitro-L-arginine after the first 30 minutes of pulsatile flow to assess the potential role of endothelial autacoids. RESULTS: Maternal oximetry and pressures remained unchanged throughout the procedure. Under fetal pulsatile flow, maternal cardiac output increased after 20 minutes of bypass and remained significantly higher than under steady flow at minute 30 (8.8+/-0.7 L x min(-1) vs 5.9+/-0.5 L x min(-1), P=.02). Maternal cardiac output in the pulsatile group also remained higher than in both steady and pulsatile blocked flow groups, reaching respectively 8.7+/-0.9 L x min(-1) vs 5.8+/-0.4 L x min(-1) (P=.02) and 5.9+/-0.3 L min(-1) (P=.01) at minute 60. Maternal systemic vascular resistances were significantly lower under pulsatile than under steady flow after 30 minutes and until the end of bypass (respectively, 9.1+/-0.6 IU vs 12.7+/-1.1 IU, P=.02 and 8.9+/-0.5 IU vs 12.9+/-1.2 IU, P=.01). Infusion of Nomega-nitro-L-arginine was followed by an increase in systemic vascular resistances from 9.3+/-0.7 IU, similar to that of the pulsatile group, to 13.5+/-1 IU at 60 minutes, similar to that of the steady flow group. CONCLUSIONS: Maternal hemodynamic changes observed under fetal pulsatile flow are counteracted after infusion of Nomega-nitro-L-arginine, suggesting nitric oxide release from the fetoplacental unit under pulsatile fetal flow conditions.     

Discriminant analysis of the Ullrich-Turner syndrome neurocognitive profile

OBJECTIVES: To evaluate the effect of fetal behavioral states on the relationship between fetal heart rate (FHR) and middle cerebral artery resistance index (MCA RI) in normal fetuses. METHODS: The FHR and MCA RI of 10 normal cases from 37 to 40 weeks of gestation were recorded consecutively over a 45-min period. Correlations between the MCA RI and FHR during resting and active phases, classified by an actocardiotocogram, were analyzed by simple regression analysis. RESULTS: The mean FHR and MCA RI were significantly higher during the active phase (140.3 +/- 6.6 bpm, 0.79 +/- 0.06) than those during the resting phase (137.4 +/- 6.8 bpm, 0.75 +/- 0.07, P < 0.01, two sample t-test). There was a significant negative correlation (r = - 0.22, n = 2642, P < 0.01) between RI and FHR during the active phase and a significant positive correlation (r = 0.28, n = 2066, P < 0.001) during the resting phase. CONCLUSIONS: The relationship between FHR and the MCA RI during the resting phase is different from during the active phase.     

Fetal response to voluntary maternal hyperventilation. A preliminary report

Maternal hyperventilation can cause transient reduction in fetal oxygen tension. Fifty women with normal and high-risk pregnancies, between the 32nd and 43rd week, were voluntarily hyperventilated; in 33, fetal heart rate (FHR) acceleration or transient tachycardia were observed (reactive FHR). Of the 33 pregnancies the outcome was good in 30 (91%) as judged by the absence of perinatal death, no fetal distress in labor and no intrauterine growth retardation (IUGR). In 14 patients in whom there was no FHR response to maternal hyperventilation (non-reactive FHR), the outcome of pregnancy was significantly worse; one infant died neonatally, 10 were either chronically (IUGR), or acutely distressed. Only in 3 was the outcome good (21%). The study showed that there is good correlation between a "reactive" FHR and favorable neonatal outcome, and between a "non-reactive" FHR and an unfavorable neonatal outcome.     

The influence of the maternal heart rate on the uterine artery pulsatility index in the pregnant ewe

We investigated the influence of the maternal heart rate on the uterine artery pulsatility index in pregnant ewes. We used an external pacemaker to alter the heart rate of 5 pregnant ewes at 16-17 weeks of pregnancy and examined the effect of changes in the maternal heart rate on the uterine artery flow velocity waveforms and the pulsatility index, as determined by Doppler velocimetry. The uterine artery pulsatility index showed a significant negative correlation with the maternal heart rate. There were no significant changes in other hemodynamic parameters. The maternal heart rate had a significant influence on the uterine artery pulsatility index.     

A study for predicting toxemia of pregnancy by the diastolic notch in pulsed Doppler flow velocity waveforms of the uterine arteries--quantitative analysis of the diastolic notch as uterine arterial index (UTAI)

To investigate the ability of measurement of the diastolic notch in Doppler flow velocimetry to predict development of toxemia of pregnancy, analysis of uteroplacental and fetal blood flow waveforms was performed. The waveforms were analyzed by calculating the resistance index (RI) and the pulsatility index (PI) and were investigated whether diastolic notches existed or not. In the prospective study, the uterine arterial index (UTAI; an index introduced to evaluate the degree of diastolic notch quantitatively) was also calculated. RETROSPECTIVE STUDY: The waveforms in the uterine arteries, the umbilical artery and the fetal vessel (inferior vena cava, descending aorta and middle cerebral artery) were measured in 153 pregnant women. PROSPECTIVE STUDY: Uterine artery velocimetry was performed at 16-23 weeks' gestation in 387 pregnant women. RESULT 1: Subjects with a diastolic notch had significantly higher rates of development of toxemia of pregnancy. Indexes of the fetal blood flow waveforms had no significant correlations with the development of toxemia of pregnancy. RESULT 2: UTAI showed an equivalently high negative predictive value (98.1%) and higher positive predictive value (17.6%) than RI (98.2%, 10.2% respectively) and PI (98.7%, 12.7% respectively). CONCLUSION: UTAI measurement was more useful for predicting toxemia of pregnancy than RI or PI.     

Maternal and fetal nitric oxide synthesis is decreased in pregnancies with small for gestational age infants

Our purpose was to evaluate whether maternal and fetal nitric oxide synthesis in pregnancies with small for gestational age (SGA) infants are different from those in pregnancies with appropriate for gestational age (AGA) infants. Maternal and fetal circulating nitrate and nitrite concentrations were compared between 30 pregnancies with AGA and 10 pregnancies with SGA at birth. End-products of nitric oxide synthesis were measured in maternal and cord venous blood samples using a fluorometric assay. Umbilical artery blood pH and PO2 were also measured. Maternal circulating nitrite and nitrate concentrations (6.91 +/- 1.27 microM) in pregnancies with SGA were significantly lower than those (11.69 +/- 1.33 microM) in pregnancies with AGA (P = 0.015). Fetal circulating nitrite and nitrate concentrations (7.54 +/- 1.09 microM) in pregnancies with SGA were also significantly lower than those (11.24 +/- 1.08 microM) in pregnancies with AGA (P = 0.024). There were no significant differences in umbilical artery blood pH and PO2 between the two groups. These results suggest that maternal and fetal nitric oxide synthesis are decreased in pregnancies with SGA infants.     

Ovine fetal-placental cocaine pharmacokinetics during continuous cocaine infusion

OBJECTIVE: To investigate fetal-placental cocaine clearance, and to determine the fetal catecholamine and cardiovascular responses to continuous intravenous cocaine infusion in fetal sheep. METHODS: Eleven pregnant ewes and their fetuses (127 +/- 2 days' gestation; term 150 days) were chronically instrumented. Fetuses received intravenous cocaine at 0.05, 0.1, or 0.2 mg/kg/minute. Fetal cardiovascular and hematologic measurements were made before and serially for 90 minutes after initiation of the cocaine infusion. RESULTS: Steady-state fetal plasma cocaine concentrations were observed by 15 minutes of infusion and averaged 136 +/- 11, 318 +/- 65, and 610 +/- 36 ng/mL, respectively, at each dose. Fetal-placental cocaine clearance rate was independent of dose (337 +/- 39 mL/kg/minute), indicating that it is a first-order pharmacokinetic process. Fetal plasma concentration of benzoylecgonine, a principle cocaine metabolite, increased throughout the study to approximately 25% above cocaine levels by 90 minutes. There were significant increases in fetal heart rate (from 169 +/- 11 to 242 +/- 36 beats per minute), mean blood pressure (from 53 +/- 4 to 63 +/- 5 mmHg), and systolic blood pressure (from 68 +/- 2 to 80 +/- 5 mmHg), with a corresponding increase in catecholamine levels seen in the fetuses infused with 0.2 mg/kg/minute. These changes were not seen in the fetuses given lower doses of cocaine. CONCLUSION: Fetal-placental clearance of cocaine is a rapid, first-order pharmacokinetic process. During prolonged cocaine exposure, plasma benzoylecgonine concentrations accumulate significantly. Significant catecholamine and cardiovascular changes are seen in fetal sheep with a continuous infusion of cocaine at 0.2 mg/kg/minute or greater.     

Effect of dehydroepiandrosterone sulfate on fetal middle cerebral artery flow velocity waveforms in term pregnancy

OBJECTIVE: To investigate whether bolus injection of dehydroepiandrosterone sulfate (DHAS) is associated with changes in fetal middle cerebral artery flow velocity waveforms in term pregnancy. METHODS: Ten normal full-term pregnant women received the administration of a 200-mg intravenous dose of DHAS in 20 ml of 5% dextrose. Ten normal full term pregnant women received 20 ml 5% dextrose as controls. Color Doppler flow imaging and pulsed Doppler ultrasonographic assessments were made on fetuses in each group before and 10 min, 30 min, 60 min, 90 min. and 120 min after DHAS or dextrose administration. The pulsatility index (PI) values for the middle cerebral artery, and umbilical artery, and fetal heart rate were recorded. RESULTS: In the DHAS group, middle cerebral artery PI decreased from baseline by 24% (p<.05) after 10 min, and the mean reduction was 22% (p<.05) after 30 min. The PI returned to the baseline value 60 min later. In the control group, there was no change in middle cerebral artery PI. No change was found in umbilical artery PI or fetal heart rate in the control or DHAS group. CONCLUSION: DHAS induces a significant decrease in the fetal middle cerebral artery PI, which suggests a possible decrease in fetal cerebral vascular impedance in term pregnancy.     

Experimental and clinical study on the blood supply of the subdermal vascular network island flap]

Vascular resistances of various fetal areas are assessed by Doppler ultrasound. The PI, RI and S/D indices are measured on the cerebral, renal, aortic and umbilical Doppler spectrum. Ratios of these indices based on the comparison of the cerebral (Rc) and the umbilical (Rp) resistances, or carotid (Rcc) and umbilical resistances, or cerebral (Rc) and aortic (Rao) resistances (Rc/Rp or Rp/Rcc, or Rc/Rao), measure the flow redistribution between the placenta and brain. The umbilical resistance indices, when greater than the upper limit of the normal range (> 2sd) are frequently associated with IUGR. (Sensitivity about 65 to 70%). Absent end diastolic flow is most of the time associated with severe IUGR and hypoxia and poor fetal outcome. A fairly good correlation was found between the existence of significantly decreased (< .2.sd) cerebral resistance and the development of post asphyxial encephalopathy in the neonate (Specificity 75% Sensitivity 87%). The earliest detectors of IUGR and hypoxia are the cerebral-umbilical cerebral-carotid, or cerebral-aortic ratios (Sensitivity 85% specificity 90%). When used as predictor of poor perinatal outcome in growth retarded fetuses, the cerebral umbilical ratio shows a sensitivity of 90% compared with 78% of the middle cerebral artery, and 83% for the umbilical artery indices. Changes of this ratio are well correlated with the fetal pO2 changes. The renal flow response to hypoxia depends on the degree of hypoxia. Opposite responses were found in case of moderate, and severe IUGR or hypoxia. Thus, it is too early to conclude if the renal indices are reliable parameters for the evaluation of fetal hypoxia. The sensitivity in predicting IUGR was for the aortic PI: 41% and for the aortic BFC (Blood flow classes): 57%. In predicting delivery for fetal distress, the corresponding values were 76 and 87%, respectively. Because the resistance indices are heart rate-dependent, it is dangerous to draw any conclusion from one single value of any of these parameters. Only several successive measurement of the Doppler indices or of their ratio, may lead to a reliable evaluation of fetal hemodynamics. In the case of significant IUGR with abnormal Doppler indices it is recommended to repeat the Doppler measurements daily both at the cerebral and umbilical or aortic level in order to follow up the fetal flow redistribution which is highly correlated with the fetal pO2 changes.     

Differences in caries recording with and without bitewing radiographs. A study on 5-year old children in the County of Bohusl?n, Sweden

OBJECTIVE: To evaluate the cerebral blood flow parameters assessed by transcranial Doppler during aortic cross-clamping and unclamping in patients undergoing abdominal aortic aneurysmectomy. METHODS: Invasive intraoperative monitoring of mean arterial pressure (MAP) and PaCO2, and right middle cerebral artery (RMCA) monitoring of blood flow parameters (mean velocity "Vm" and pulsatility index "PI") by transcranial Doppler were performed as well as evaluation of the four parameters during these subsequent periods: pre-cross-clamping, pre-unclamping, unclamping and 1-5-10-20 minutes after abdominal aortic unclamping. RESULTS: No significative changes of MAP, PaCO2, Vm and PI were noticed during the aortic cross-clamping period (77.5 +/- 18.5 SD minutes). During aortic unclamping Vm and MAP decreased (64 +/- 20 vs 52 +/- 20 cm/sec, p < 0.05, and 101 +/- 8 vs 80 +/- 15 mmHg, p < 0.01, respectively). At the 1th post-unclamping minute there was an increase from pre-unclamping values of Vm (75 +/- 20 cm/sec, p < 0.05) and PaCO2 (42 +/- 1.5 vs 36 +/- 2 mmHg, p < 0.05), with persistent reduction of MAP (92 +/- mmHg, p < 0.05), even more evident at the 5th post-unclamping minute (Vm = 93 +/- 25 cm/sec; PaCO2 = 46 +/- 1.2 mmHg, p < 0.001, and MAP returned to pre-unclamping value), in which there was also a decrease of PI (0.65 +/- 0.16 vs 0.78 +/- 0.2, p < 0.05). At the 10th minute Vm (83 +/- 24 cm/sec, p < 0.02) and PaCO2 (41 +/- 1.5 mmHg, p < 0.05) increments were present together with persistent reduction of PI (0.69 +/- 0.17, p < 0.05), while at the 20th post-unclamping minute also Vm, PaCO2 and PI returned to their pre-unclamping values. CONCLUSIONS: The Vm decrease at aortic unclamping might correlate with the acute changes in MAP (blood steal hypovolemia) and is likely due to an inadequate cerebral autoregulatory response to abrupt MAP changes. The arterial CO2 increase after aortic unclamping could lead to a dilation of cerebral arterioles and a rise of CBF (increase of Vm and decrease of PI). Transcranial Doppler is a simple and reliable technique for the monitoring of cerebral blood flow parameters and seems to be quite suitable for the recognition and the quantification of changes in these parameters induced by surgical manoeuvres able to produce hemodynamic instability.     

Fetal circulation and malaria

OBJECTIVE: To quantity the fetal vascular changes during flare-up, and to evaluate the sensitivity and the specificity of Doppler indices for the prediction of acute fetal distress at the end of the pregnancy. METHOD: Every day of flare-up the umbilical resistance (Rp), cerebral resistance (Rc), cerebro-placental ratio (CPR = Rc/Rp), and hypoxia index (HI = delta % CPR x crisis duration) were calculated. RESULTS: Twenty-three pregnancies were investigated at St Laurent du Maroni Hospital (French Guiana). During flare-ups the Doppler placental resistance increased (placental disorder), cerebral resistance decreased (vasodilation), CPR decreased (flow redistribution toward the brain), and HI increased. An abnormal CPR (< 1) was associated with abnormal fetal heart rate (FHR) in 61.5% of the cases, a CPR > 1 was associated with a normal FHR in 80% of the cases. (sensitivity: 80%, specificity 61%). A CPR < 1 was associated with one of the abnormalities (abnormal FHR, cesarean section, abnormal Apgar) in 71% of the cases, a CPR > 1 was associated with normal delivery in 55% of the cases (sensitivity: 71.4%, Specificity 55%). A HI higher than 150 was associated with abnormal FHR in 75% of the cases, a HI < 150 was associated with normal FHR in 90% of the cases (sensitivity: 89%, specificity: 77%). Lastly the combination (HI > 150 + CPR < 1) was associated with abnormal FHR in 80% of the cases, 1 or 2 of these parameters were associated with normal FHR in 84.6% of the cases (sensitivity: 80%, specificity: 84%). The minimum CPR and the HI during malaria flare-up can be used to predict acute fetal distress at delivery.     

MRI does not change fetal cardiotocographic parameters

The aim of this study was to determine whether magnetic resonance imaging (MRI) has any effect on fetal cardiotocographic (CTG) parameters or movement incidence. Sixteen mothers were examined during the last trimester at 28-39 weeks (mean 33 weeks; SD 4) of gestation due to a suspected fetal anomaly found in antenatal ultrasonography (US). MR imaging was performed using Siemens Magnetom Vision 1.5 T equipment with a 25 mT/m peak gradient amplitude. T2-weighted images were produced with HASTE and TRUE-FISP sequences and T1-weighted images with a 2D FLASH sequence. A four-element phase-array coil was used as the receiver. Before and after MRI-examination, a computerized analysis of the fetal heart rate (FHR) was produced. Basal FHR, short-term variation (STV) and fetal movements were calculated. The mean basal FHR was 136 beats/min (SD 11.6) before, and 133 beats/min (SD 8.9) after (P = 0.158). Short-term variation was in the normal range for both CTG-tracings: mean 9.7 ms (SD 2.7) and 8.8 ms (SD 2.8) (P = 0.196). The median for fetal movements before MRI was 48/h, and after MRI 24.5/h (P = 0.98). MRI at high field strength with powerful gradients did not affect fetal heart activity or movement incidence.     

Evaluation of the accuracy of a new ultrasonic fetal heart rate monitor

An indirect Doppler fetal monitoring system has been developed and validated by computer comparison of simultaneous fetal heart rate (FHR) with Doppler and scalp ECG of high-risk patients during labor. The difference in measurement of FHR averaged 0.3 b.p.m., and 93 per cent of the Doppler FHR measures were within 10 b.p.m. of the ECG FHR. If interinstrument difference is discounted, 96 per cent were within 10 b.p.m. All types of decelerations and variability were well approximated. Doppler FHR from the instrument described may be relied upon as valid clinical information and may be obtained from over 90 per cent of labor patients with 93 per cent accuracy.     

Effect of antenatal administration of thyrotrophin releasing hormone on fetal flow velocity waveforms

AIM: To determine whether antenatal administration of thyrotrophin releasing hormone (TRH), to promote lung maturation, alters blood flow through the fetal middle cerebral, umbilical artery, or ductus arteriosus and through the maternal uterine arteries. METHODS: The effect of transplacentally administered TRH on the fetal circulation was prospectively evaluated in 30 patients between 24 and 34 weeks' gestation. TRH (400 micrograms) was given to the mother intravenously either as a bolus or an infusion. Fetal effects were determined by measuring the maximum velocity and pulsatility index (PI) in middle cerebral artery, ductus arteriosus, uterine artery and umbilical artery Doppler waveforms. Measurements were made immediately before, and 10 and 60 minutes after maternal TRH administration. RESULTS: Intravenous injection of TRH had no significant effect on PI in the uterine, umbilical, or middle cerebral artery and the ductus arteriosus within 60 minutes of administration in either group. CONCLUSION: The antenatal use of TRH in conjunction with steroids for fetal lung maturity does not affect utero-placental or fetal haemodynamic variables, as measured by Doppler. These findings, therefore, do not support the suggestion that antenatal intravenous administration of TRH either as bolus or infusion may have immediate adverse vascular effects in the fetus.