Henry Nisell

Blood pressure and renal function seven years after pregnancy complicated by hypertension

Objective To assess the occurrence of chronic hypertension and renal disorder after gestations complicated by pregnancy induced hypertension or pre‐eclampsia and to define background factors and laboratory analyses at follow up examination which discriminate between women who remain normotensive and those who develop hypertension.

Change in estimated cerebral perfusion pressure after treatment with nimodipine or magnesium sulfate in patients with preeclampsia

OBJECTIVE Data are accumulating to suggest that cerebral perfusion pressure may be either abnormally high or low in preeclampsia and eclampsia. Little is known of the cerebral perfusion pressure effects of magnesium sulfate or nimodipine. Our objective in this study was to compare the change in cerebral perfusion pressure in patients with severe preeclampsia randomly selected to receive nimodipine or magnesium sulfate. STUDY DESIGN Patients with severe preeclampsia were randomly selected to receive magnesium sulfate (6 g bolus and 2 g/hr intravenous infusion) or nimodipine (60 mg taken orally every 4 hours). Transcranial Doppler ultrasonography was used to measure flow velocities in the right and left middle cerebral arteries, and the results were averaged. Measurements were obtained before treatment (baseline) and 30 minutes after the magnesium sulfate bolus was completely infused or 30 minutes after the nimodipine was ingested. Studies were performed before any other intervention. The person performing the ultrasonography was unaware of the patients group assignment. Estimated cerebral perfusion pressure was calculated with the following formula: Estimated cerebral perfusion pressure = Velocity(mean) x [(Blood pressure(mean ) - Blood pressure(diastolic ))/(Velocity(mean) - Velocity(diastolic ))]. The difference between estimated cerebral perfusion pressure at baseline and after treatment was compared between the 2 groups by means of the Mann-Whitney rank sum test. RESULTS Nine patients were randomly selected to receive nimodipine and 12 to receive magnesium sulfate. Patient demographics and severity of condition were not significantly different between the 2 groups. The change in estimated cerebral perfusion pressure was significantly different between the groups. Estimated cerebral perfusion pressure increased after nimodipine use and decreased after magnesium sulfate use. CONCLUSION Shortly after administration to patients with severe preeclampsia, nimodipine resulted in increased cerebral perfusion pressure in comparison with magnesium sulfate.

Effects of nitroglycerin on the uterine and umbilical circulation in severe preeclampsia

Objective To determine the effects of nitroglycerin on placental circulation in severe preeclampsia. Methods Twelve women with severe preeclampsia were examined. Uterine and umbilical artery pulsatility indices (PI) were assessed by pulsed Doppler ultrasound before and after infusion of nitroglycerin, starting at 0.25 μg/kg per minute with stepwise dosage increases until a diastolic blood pressure (BP) of 100 mmHg was achieved. Blood pressure and heart rate were recorded every 5 minutes. Blood was sampled for analysis of the second messenger of nitric oxide, cyclic guanosine monophosphate (cGMP), before and at the end of the infusion. Results During the infusion, the mean systolic BP de-creased from 161 (95% confidence interval [CI] 154–169) to 138 mmHg (95% CI 131–146), and the diastolic pressure decreased from 116 (95% CI 111–122) to 103 (95% Cl 96–110) mmHg (P < .01). The PI of the uterine artery did not change significantly (1.23 [95% CI 1.01–1.61]) versus 1.30 [95% CI 1.01–1.88]), whereas umbilical artery PI decreased significantly (P < .01), from 1.35 (95% CI 1.09–1.73) to 1.20 (95% CI 1.05–1.40), with a more pronounced decrease in patients with high basal values. Cyclic GMP remained essentially unchanged (6.4 [95% CI 5.4–7.71 versus 5.5 [4.7–6.6] nmol/L). Conclusion The reduction in the PI of the umbilical artery during nitroglycerin-induced BP reduction implies vasodilation in the umbilical circulation. The absence of an increase in cGMP does not support the view that the nitroglycerin effect is reflected by the plasma concentration of cGMP.

Association of cerebral perfusion pressure with headache in women with pre-eclampsia

Objective To study estimated cerebral perfusion pressure and its relation to headache and scotomata in women with pre‐eclampsia.

Sympatho-adrenal and cardiovascular reactivity in pregnancy-induced hypertension. I. Responses to isometric exercise and a cold pressor test

Summary. Sympatho‐adrenal and cardiovascular reactivity was studied in patients with pregnancy‐induced hypertension (PIH) and healthy pregnant controls subjected to an isometric handgrip test and a cold pressor test both during and after the pregnancy. At rest, heart rate was higher in the PIH group than in the control group both during and after pregnancy. Forearm vascular resistance was not affected by PIH or by pregnancy per se. During pregnancy arterial plasma adrenaline levels were suppressed in the control group both when compared with the PIH group and postpartum values. Arterial noradrenaline levels were similar and normal in the two groups at both examinations. The iso‐metric exercise increased systolic and diastolic blood pressures, heart rate and noradrenaline and reduced vascular resistance similarly in the PIH and control groups on both occasions. Vasoconstrictor responses to the cold pressor test were reduced during prenancy but there were no differences between the groups on either occasion. Noradrenaline responses to the cold pressor test were not influenced by PIH or by pregnancy per se. During pregnancy adrenaline responses to the two tests tended to be reduced in the controls but not in PIH. Our results indicate enhanced adrenomedullary activity in PIH when compared with the suppressed activity in normal pregnancy. Cardiovascular reactivity to the tests was similar in the PIH and control groups. The normal arterial noradrenaline levels at rest and during provocation do not support the contention of a generalized increase in sympathetic nerve activity in PIH

Changes in flow velocity, resistance indices, and cerebral perfusion pressure in the maternal middle cerebral artery distribution during normal pregnancy

Background. There are few longitudinal data currently available detailing the normal changes in maternal cerebral hemodynamics during human pregnancy. This lack of information limits the study of pregnancy‐associated cerebrovascular adjustments and, in particular, preeclampsia, where the brain appears to be especially susceptible to ischemic and encephalopathic injury. Our objective was to define the hemodynamic changes, specifically velocity, resistance indices, and cerebral perfusion pressure, in the middle cerebral artery (MCA) distribution of the brain during normal pregnancy.

Are Women with Polycystic Ovary Syndrome at an Increased Risk of Pregnancy-Induced Hypertension and/or Preeclampsia?

OBJECTIVE To study whether there is an increased risk of glucose intolerance and hypertensive complications during pregnancy in women with polycystic ovary syndrome (PCOS) and if there is an adverse pregnancy outcome. METHODS In a retrospective case-control study, pregnancies and neonatal outcome were compared in 33 women with PCOS and 66 women without PCOS. The women were treated at Huddinge University Hospital; antenatal care was given at associated outpatient units. MAIN OUTCOME MEASURES Blood glucose and blood pressure during the different trimesters. Pregnancy outcome in terms of gestational length, birth weight, and need for neonatal intensive care. RESULTS No significant differences were found in blood glucose levels between the groups. There were also no differences in blood pressure during the first and second trimester. However, during the third trimester and labor, the PCOS group had a significantly higher blood pressure than the control group. Apart from a tendency toward reduced growth of twins in PCOS mothers, the babies were healthy, overall, with few problems in the neonatal period. CONCLUSIONS No major differences with regard to perinatal outcome in pregnant women with and without PCOS were found. An increased risk of hypertensive disorders in the third trimester and during labor was demonstrated in the PCOS group. This suggests that in the antenatal care of women with PCOS, attention should focus on blood pressure in order to reduce the risks of morbidity associated with hypertension.

Maternal and fetal levels of a novel polypeptide, endothelin : evidence for release during pregnancy and delivery

The occurrence of endothelin (ET), a recently discovered polypeptide with potent vasoconstrictor properties, was studied in maternal and umbilical blood and amniotic fluid. The level of ET-like immunoreactivity (ET-LI) in maternal plasma was in most cases below the detection limit of the radioimunoassay, i.e. less than 2 pmol/l. The median concentration of ET-LI in the umbilical artery and vein before the initiation of breathing was 14.9 and 10.9 pmol/l, respectively. When sampling was performed after fetal breathing had begun, the arterial concentration increased to 93.7 pmol/l. Labor was not associated with increased concentrations of ET-LI, however, since neonates delivered by elective cesarean section had similar ET-LI in blood and amniotic fluid as after vaginal delivery. An approximately fivefold increase in the amniotic fluid ET-LI was seen at term as compared to early mid-trimester values. Reversed phase HPLC characterization revealed that the observed ET-LI mainly corresponded to ET-1. It is suggested that ET-1 may contribute to the fetal hemodynamic changes, e.g., closure of the umbilical vessels occurring at delivery.

Preeclampsia may cause both overperfusion and underperfusion of the brain. A cerebral perfusion based model

BACKGROUND The hypothesis was that low cerebral perfusion pressure is more common in women with mild preeclampsia as compared to those with severe preeclampsia, while high cerebral perfusion pressure is more common in women with severe preeclampsia than in women with mild preeclampsia. DESIGN Prospective, observational study. SETTING University teaching hospitals. METHODS Transcranial Doppler ultrasound was used to measure the blood velocity in the middle cerebral arteries of 54 patients with mild preeclampsia and 44 patients with severe preeclampsia. Blood pressure was measured simultaneously. Cerebral perfusion pressure was calculated and plotted on the same axes as data from 63 normal pregnant women. Data outside of the 95% prediction limits were regarded as abnormal. All studies were prior to labor, and before volume expansion or treatment. ANALYSIS Students t-test, Mann Whitney U test, and Fishers exact test as appropriate with two-tailed p<0.05. MAIN OUTCOME MEASURE The number of patients in each group with cerebral perfusion pressure values outside the normal 95% prediction limits. RESULTS Almost the same number of women with mild (21/54=39%) and severe (15/44=34%) preeclampsia had measurements within the normal range (p=0.78). Mild preeclamptic women were more likely to have low (28/54=52%) rather than high cerebral perfusion pressure (p<0.001), while severe preeclamptics were more likely to have high cerebral perfusion pressure (26/44=59%) than low (p<0.001). CONCLUSIONS In preeclampsia the brain can be normally perfused, underperfused and over-perfused. Although many women with mild preeclampsia will have underperfusion (52%), and a significant number of women with severe preeclampsia will have overperfusion (59%), many preeclamptic women have cerebral perfusion within the normal range.

Evaluation of a noninvasive transcranial Doppler and blood pressure-based method for the assessment of cerebral perfusion pressure in pregnant women.

Objective: We have developed a Doppler method for the estimation of cerebral perfusion pressure (CPP) using noninvasive techniques. Our objective was to evaluate our new method in pregnant women. Methods and Materials: Laboring women with a lumbar epidural in situ had transcranial Doppler interrogation of the maternal middle cerebral artery (MCA) to measure systolic, diastolic, and mean velocities. A pressure transducer was connected to the epidural catheter and pressure was recorded. Systolic (SBP), diastolic (DBP), and mean (MAP) blood pressure were taken with a Dinamap monitor. Doppler estimated CPP (mm Hg) = [Vmean/ Vmean- Vdiastolic](MAP – DBP) and directly measured CPP = MAP – Epidural pressure data were plotted on a Bland–Altman graph with limits of agreement. The mean difference (the mean of the sum of both positive and negative differences) and absolute difference (the mean of the sum of the absolute differences) were calculated. In addition, linear and polynomial regression analyses were performed. Results: Twenty laboring women were studied. All had normal pregnancies. The mean maternal age was 28 ± 7 years and the mean gestational age was 39 ± 2 weeks. The mean maternal MAP was 77 ± 12 mm Hg. The Bland–Altman plot showed a mean difference of 2.2 mm Hg at a mean CPP of 65 ± 12 mm Hg; with a standard deviation of 4.8 mm Hg, the absolute difference was 3.9 ± 3.0 mm Hg at a mean CPP of 65 ± 12 mm Hg. The regression analysis showed an r = 0.92, r2 = 0.86, and p < 0.0001. Conclusions: Our formula allows the estimation of CPP using a simple calculation and noninvasively acquired data. This method may be of use for frequent, easy, and accurate CPP and intracranial pressure estimation and may, as such, have significant research and clinical applications.